UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The reactions of lithium with nitrogen and water vapour Irvine, Wayne Ronald 1961

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1961_A6_7 I7 R3.pdf [ 4.52MB ]
Metadata
JSON: 831-1.0106079.json
JSON-LD: 831-1.0106079-ld.json
RDF/XML (Pretty): 831-1.0106079-rdf.xml
RDF/JSON: 831-1.0106079-rdf.json
Turtle: 831-1.0106079-turtle.txt
N-Triples: 831-1.0106079-rdf-ntriples.txt
Original Record: 831-1.0106079-source.json
Full Text
831-1.0106079-fulltext.txt
Citation
831-1.0106079.ris

Full Text

The Reactions Of Li th ium With Nitrogen And Water Vapour by Wayne Ronald Irvine A Thesis Submitted In P a r t i a l F u l f i l l m e n t ' Of The Requirements For The Degree Of Master Of Science i n the Department of Mining and Metal lurgy We a c c e p t ' t h i s thes i s as conforming to the standard required from candidates for the degree of Master Of Science Members of the Department of Mining and Metal lurgy The U n i v e r s i t y Of B r i t i s h Columbia A p r i l , 1961 In presenting t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree th a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree that permission f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood t h a t copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be allowed without my w r i t t e n permission. Department of Mining and Metallurgy, The U n i v e r s i t y of B r i t i s h Columbia, Vancouver $, Canada. Date May 3rd, 1 9 6 l  ABSTRACT The react ions of l i t h i u m disks with dry and moist ni trogen and with water-vapour were invest igated at temperatures from 22 to 70 degrees Centigrade with the use of a thermal balance. The reac t ion in ni trogen commenced with nucleat ion of l i t h i u m n i t r i d e at corners and edges of the sample and the reac t ion proceeded by l a t e r a l growth of these n u c l e i through the specimen. In moist gas, th i s reac t ion was accompanied by the simultaneous formation of l i t h i u m hydroxide at the plane surface of the specimen. Based on v i s u a l observations of the samples during the r e a c t i o n , a model descr ib ing the geometry of nucleus formation was constructed and was used to ca lcu la te growth v e l o c i t i e s from the react ion curves obtained with the thermal balance.The dependence of growth v e l o c i t y on temperature, n i trogen p a r t i a l pressure, and the moisture content of the reac t ion gas was inves t igated . The reac t ion with water-vapour was observed to proceed i n three d i s t i n c t stages.The r e s u l t s have been explained i n terms of a model invo lv ing r e c r y s t a l l i z a t i o n and hydration of an i n i t i a l l y coherent l i t h i u m hydroxide f i lm. . i i ' ACKNOWLEDGEMENTS The author i s gra te fu l f o r f i n a n c i a l a id in the form of a Fel lowship provided by the Foote Mineral Company„. The supervis ion of Dr. J.A.»Lund and the t e c h n i c a l ass istance o f Mr, R.. Go Butters , who constructed the recording balance, are g r a t e f u l l y acknowledged. The author i s indebted t o Mrs1. Margaret Armstrong for her many he lp fu l d iscuss ions . . Ill» TABLE OF CONTENTS . Page I a U\[ X RO D U O i . ION o o o « o « » o o o o o e « o e o o e « o o " o o e o o o o o o a o a o o o o - 1 A* General Considerations * . o . , . . . . . . . .« . . . <>. . . . I B w Previous Work with Lithium ....,..„.........„, 3 Co. Scope of the Investigation. „„„.„..„ . .. „ . 0 » . . . 4 « o © 6 • o o o o o o o o o o o o a o o o o o o -o a a o I I . EXPERIMENTAL' PROCEDURE A.. Design of Thermal Balance and Auxiliary .i^ p jp cl I" d t U. S O O O C O O O O O O O O O O O O O ' O O O O O O O O O O O o o » 0 o 0> © 3'' .Bo. Specimen Preparation ........................ 7 C„. Procedure O O O O O O O O O O o o O © O O O O O O O O O O O .« O O O O O o o O 0 I I I , RESULTS FOR REACTIONS WITH DRY AND MOIST NITROGEN.. . 10i A'«. Reaction with Dry Nitrogen . . . . . . . . . . . . . . . . . . . '10-1 o« R© SVllt/S oooooooo ooooooooo-oooooo© o o o o o o o o o o -1-0 2 0. Discussion of Results for the Reaction in Dry Nitrogen ............ ............. . 13 B. Reactions with Moist Nitrogen . ............... 14 1 . , -Effect of Reaction Temperature .......... . • 1U • 2 . The Effect of the Moisture Content of the Reaction 3o Effect of Partial Pressure', of Nitrogen . 0 0 1-5 C Analysis of the Results Obtained Using ^ i O . l S t N 11 r O 1*1 0 0 0 0 0 0 » o o o o o o o o o o e o o o o o o o « O O o o 1^ 1... Analysis' of Results for Run in which Surface Nucleation was Abs,ent ............ 22 2. Analysis of Results for Ruin in which. Surface Nucleation was Present .". ........ 24 D 9 DXSCUSSlOn 0.f R© SU.1 *t> S • o o o o o o o - o o o o o o o o o o o o o o o o * ' 0 I... Factors Influencing Nucleation Rate ...... 30 . 2„ Factors Influencing Growth' Rate <, ........ . 31 E Q S O U F C 6 S O T ErrOT* o o o o o t . o o o o o o o o o o o c o o o o o o . o o o o 3 5 F 9 G OT^C 1U. S 1 0 IT S o o o o o o e o o o o c o o o o o o o o o o o o o o o o o o o o o 3 7 IV. REACTION! WITH WATER VAPOUR . . ... .................. . . 33 A. Reaction with-Dry and Moist Oxygen .......... 3'$ B„. Reaction with Water Vapour . .................. 3$ •I.-General Characteristics of the Reaction....' 3$ 2 . Comparison of Oxygen, Argon, and Helium as ' Carrier Gases; .............. .... 43 3:« Effect of Temperature .................... 43 4 . Effect of Partial Pressure of Welt©!*- VcH-pOU.!** o o o o o o o ' o o 0 0 0 0 o o o o © o o o o o t > © © 0 0 0 A* C „ Discussion of Results. ....................... . 46 1, General Considerations ....... ........... . 46 2 . The Effect of Partial Pressure of Water , in the Reaction Gas ............. .......... 4$ 3 , Suggested Mechanism ....... ................ 48" D o S o u. r c © s o JT E r r o r o o o o o o o . o © o o © o o o o o o o o © o o o o o © o 5 1.' Errors due to Variations in Surface COridltlOn 0 0 0 ' © 0 0 0 0 f t » 0 0 © 0 0 © 0 © » © 0 © 0 © » » 0 0 © 0 © 0 i v . TABLE OF CONTENTS ( continued ). page 2. Error in Temperature Measurement Due to Liberated Reaction Heat................... $2. 3 . Zero 4 . Errors due to Transport of Water Molecules to the Lithium-Hydroxide: Gas I n t e r f e r e . . . 5 3 E <> Conclu.sxoris • © © © o © » » » © o © © © © i > « o < i o o « © o o « o u © © » » » 5 3 V" 0* BIBL 1 0 GRAPH IT o o o c o o ° » * o o o e o © o < » © « o « o 9 0 o a o * o « < > * o < » « « o o 5 5 56 V " X c* A.P PEN D I G E S 0000000© o » » © © • • • * » e © o o o » © o o © o » 0 o © » a o o ©• © • A,Appendix 1 ( Results for Reactions with Bo Appendix 11 ( Results for Reactions with Wcl t 6 IT" VS. POUT ) O O O O O O O G O O e O O O O O O O O O O O G O O V O ' O O " * 66 V/ . LIST OF FIGURES NO. Page 1. S c h e m a t i c D r a w i n g of Experimental Apparatus ........ 6 2 „ Photograph o f t h e Apparatus ........................... 9 3-o Reaction Curve f o r a Rectangular Specimen Heated i n Dry N i t r o g e n a t 110°C 11 4.. Specimen Reacted i n Dry N i t r o g e n a t 110°C ........... 12 5» Specimen f o r which Re a c t i o n was I n i t i a t e d i n Moist Gas and then Continued i n Dry Gas . . . . . . . . . . . . . . . . . . 12 6. Specimen Reacted i n M o i s t N i t r o g e n a t 40°C 12 7«. R e a c t i o n Curves f o r Samples R e a c t e d i n M o i s t N i t r o g e n a t V a r i o u s Temperatures ....... ....................... 16 8. Re a c t i o n Curves f o r Three Samples R e a c t e d i n M o i s t 9o R e a c t i o n Curves f o r Samples R e a c t e d a t 40°C i n Gases of D i f f e r e n t Compositions .... ........... ........... 1$ 10. Schematic R e p r e s e n t a t i o n o f Arrangement of L i t h i u m N i t r i d e During a R e a c t i o n .......................... 19 11.. Graph of" Incremental R e a c t i o n Rate v s . Reaction Time f o r Samples Reacted a t 45°C ........................ 21 12. Graph Showing the Dependence of I n t e r f a c e V e l o c i t i e s on the Reaction Temperature ........................ 23 13. A r r h e n i u s P l o t s f o r I n t e r f a c e V e l o c i t i e s ........... 25 14. H y p o t h e t i c a l Arrangement o f L i t h i u m N i t r i d e f o r a .Sample Reacted i n Moist N i t r o g e n ................... 27 15. Dependence of Re a c t i o n V e l o c i t i e s a t 45°C on P a r t i a l P r e ssures of N i t r o g e n and Water Vapour ............. 28 16. E f f e c t of N i t r o g e n P a r t i a l Pressure on R e a c t i o n 17r R e a c t i o n Curves f o r Samples Reacted i n Moist Oxygen a t V a r i o u s Temperatures ..................... 39 18. R e a c t i o n Curves Obtained at 3 5°C i n Moist Oxygen , Argon and Helium ................................... 40 v i e ' LIST OF FIGURES ( CONTINUED ) NO'. Page 19. Changes i n Surface Appearance of Specimens i n R e l a t i o n to a Reaction Curve ....................... 42 20.. Arrheniu :s P l o t s f o r Reaction Rate Constants ........ 44 21„ Dependence of Reaction Rate Constants on P a r t i a l Pressure of Water Vapour at 3 5°C ................... 45 V l l o LIST OE TABLES. NO.. Page APPENDIX 1 . l o Reaction Rates in. Dry Nitrogen at 1 1 0 ° C . „ . „ „ . . „ „ . . . 5 6 20 Reaction Rates in Moist Nitrogen at Various 1?G ffip 6 IT S. t Q S o o o o o o o o o o « o o » o o o o o o o o o o » e o * o o o » o » o o o o * o 57 3 o Analysis, of Results of Runs in Moist Nitrogen . . . „ . „ 5 9 4. E f f e c t of Nitrogen P a r t i a l Pressure on Reaction VQ l O C l t y cit A*5 G O O O O O O O O O O O O O O O U O O O O O O O O O O O O O O G O O O O 6 0 5» E f f ec t of Water P a r t i a l Pressure on . ' Reaction V e l o c i t y at 4 5 ° C 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 . 0 0 . 0 0 0 0 0 0 0 6 0 6 . E f f ec t of Temperature and Gas Composition on Nucleat IO IT Rclt© 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o c 0 0 e o o • o * 0 0 6 l 7 . Relat ive Reaction Rates of C i r c u l a r and Rectangular Sp 6 C 11716 3T S o o o o o o o o o o o o » o o c o o o o o o o o o o c o o o o o o o 0 0 0 0 0 0 0 0 62 80 X-ray D i f f r a c t i o n Data for Specimens Reacted in Moist N 11T* O ^ 61"l St 5 G 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o o o o o o o o o o o o o e o o * o « © » o ^3 9» Reaction Rates Occuring in Dry Nitrogen a f t er I n i t i a t i n g the Run in Moist Nitrogen . . . . . . . . . . . . . . . 6 4 1 0 o Analys i s of Results for Runs Carr ied out in Dry Nitrogen af ter I n i t i a t i n g the Run in Moist Nitrogen . O . o „ . o o o 6 5 APPENDIX 1 1 l o Weight Increases of Lithium Disks Reacted in Moist Oxygen at Various Temperatures . . . . . o o o . . . . . . . . . . . » . 6 6 2 0 Summary of Results for Reactions in Moist Oxygen „ „ . 6 8 3 . Weight Increases of Lithium Disks Reacted with Moist Helium at Various Temperatures . . . . . 0 . . . . . . . . . . . . . 0 . 6 9 4. Ef fec t of Water P a r t i a l Pressure on Reaction Rates . . 7 0 5 . X-ray D i f f r a c t i o n Data for Specimens Reacted with WcX "tf © JT* Vcl pOU.37 o o o o o o o o o o o o € . o o o u « o o o o o o o # o o o o o o o » o o o o O THE REACTIONS OF LITHIUM; WITH NITROGEN AND WATER V/APOUR I I N T R O D U C T I O N S A. GENERAL C:ONSIDERA.TIQNS The reac t ion between a metal and a gas begins at the metal-gas interface and usual ly the reac t ion product forms an intermediate layer between the metal and the gas. The reac t ion may be regarded as invo lv ing a ser ies of consecutive steps inc lud ing , for example: 1. Transport of gas molecules to the react ion layer-gas i n t e r f a c e . 2. Adsorption at the in t er face . 3. D i f fus ion of one or both of the reac t ing species across the reac t ion l a y e r . 4. Chemical r eac t ion to cause increased thickening of the reac t ion l a y e r . Depending on the i n d i v i d u a l case, other steps would have to be added to the l i s t above. Quite genera l ly , however, the o v e r a l l rate of a react ion which proceeds by several successive steps i s determined by the rate of the slowest step and the determination of the r a t e - c o n t r o l l i n g step i s one of the primary object ives of any inves t iga t ion deal ing with the oxidat ion of metals . Under normal condit ions steps 1 and 4 above general ly occur rap id ly ,and commonly the rate of adsorption or d i f f u s i o n determines the o v e r a l l rate of the r e a c t i o n . 2.. The r a t e - c o n t r o l l i n g step, which appl ies under one set of condit ions need not apply under another. For example, at low p a r t i a l pressures of the react ion gas i t i s probable that the o v e r a l l rate of the react ion i s determined by the rate of transport of gas molecules to the specimen. The o v e r a l l rate would be pressure dependent. At higher pressures, the surface might be completely covered by gas molecules and d i f f u s i o n across the react ion layer would be r a t e - c o n t r o l l i n g and, moreover, the react ion rate would be pressure-independent, Even under a constant set of external condi t ions , reac t ion rates may change i n response to phys i ca l changes . in the nature of the reac t ion l a y e r . In th i s connection metals may be grouped into two c lasses according to whether the r a t i o of the volume of the reac t ion product to the volume of metal consumed in creat ing i t i s l ess than or greater than unity. . (1) In the former case the f i l m i s l i k e l y to be in a state of tension and might e a s i l y develop a network of cracks which extend almost but not e n t i r e l y to the metal surface . The rate of ox idat ion i s then contro l l ed by the d i f f u s i o n of the reactants through a t h i n continuous layer next to the metal . The outer port ions of the layer are broken-up by cracks and the react ion rate i s not influenced by the thickness of the layer and hence i s constant with time. In the case of a metal for which the volume r a t i o i s greater than un i ty , the f i l m i s i n a state of l a t e r a l compression. According to Evans (2):,mechanical breakdown should assume the form of b l i s t e r i n g when the adhesion of the layer to the metal surface is weak and of shear-cracking when adhesion is strong and cohesion is weak. In either case, failure of the film should lead to discontinuities in the reaction rate. Recrystallization is another mechanism through which a reaction layer might develop a network of cracks or flaws (3). In this connection i t is considered that sufficient strain energy is' built up • in the reaction layer to provide a driving force for recrystallization. B. PREVIOUS WORK WITH LITHIUM The reaction of lithium with water vapour has been studied previously by Deal and Svee (4) but at higher temperatures and partial pressures of water than those employed in the present investigation. The reaction times employed did not exceed 2 hours and the reaction was found to proceed according to a logarithmic rate law. The rate constant was found to be independent of the water vapour pressure over a range 22-55 nun Hg. No lower limit to the pressure-independent region was observed since the lowest pressure employed was 22 mm Hg. The energy of activation for the reaction was 6.2 to 5.5 cal / mole depending on the water vapour pressure. It is reported (5) that lithium does not react with oxygen below l00°C,but that at higher temperatures i t reacts rapidly. However, Yamaguti (6), employing an electron diffraction method, examined the surface products which formed on a fresh lithium surface after exposure to room a i r f o r 5 minutes and r e p o r t e d observing, mixed c r y s t a l s of l i t h i u m hydroxide ( LiOff ) and l i t h i u m oxide ( L i 2 0) .. Belyaev et a l , (7) s t u d i e d the r e a c t i o n o f ' l i t h i u m with moist a i r u s i n g a g r a v i m e t r i c method. They r e p o r t t h a t , f o r h u m i d i t i e s g r e a t e r than $0 percent the r e a c t i o n products were l i t h i u m " h y d r o x i d e and carbonate. At lower moisture l e v e l s l i t h i u m n i t r i d e formed. A drop i n the r e a c t i o n r a t e was r e p o r t e d to occur at temperatures above 3 5 degrees Centigrade. The r e a c t i o n o f l i t h i u m with dry n i t r o g e n between -50 and +'23'degrees Centigrade was s t u d i e d by Frankenburger (9) who f o l l o w e d the r e a c t i o n by measuring the drop In n i t r o g e n •pressure i n a c l o s e d system. The r e s u l t s suggested t h a t the o v e r a l l r e a c t i o n r a t e from -50 to 4 5°C was c o n t r o l l e d by the speed of the r e a c t i o n ( i e . the speed of a c t u a l chemical combination between l i t h i u m a n d ' n i t r o g e n atoms) but t h a t from 5 to 23°C the r a t e was c o n t r o l l e d by d i f f u s i o n of n i t r o g e n molecules through a porous l i t h i u m n i t r i d e l a y e r which had formed u n i f o r m l y over the s u r f a c e o f the specimen. C. SCOPE OF THE PRESENT INVESTIGATION The primary o b j e c t of t h i s i n v e s t i g a t i o n was to study the nature of the c o r r o s i o n of l i t h i u m by c e r t a i n gaseous atmospheres. I t was o r i g i n a l l y intended to extend t h i s study to l i t h i u m a l l o y s , " t u t the experiments with the pure metal proved to be s u f f i c i e n t l y demanding i n themselves. II EXPERIMENTAL: PROCEDURE A. DESIGN OF THERMAL BALANCE AND AUXILIARY APPARATUS j The react ions were followed by measuring the increase in weight of a sample during the course of the r e a c t i o n . The apparatus used i s shown d iagramat ica l ly i n Figure 1. The specimen was contained in an aluminum basket l i n e d with platinum gauze which'was suspended inside a glass reac t ion vesse l by means of a chain-attached to the balance arm. The react ion vesse l was immersed in a constant temperature bath. The reaction' gas was preheated i n a copper s p i r a l before entering the react ion v e s s e l . The temperature was measured with,a thermocouple and contro l l ed to wi th in X 0 . 2 C using a mercury thermoregulator pos i t ioned in the o i l bath. A s t i r r e r was used to ensure uniformity of temperature within the bath. Cyl inder gases were employed for a l l the react ions s tudied. For reac t ions , invo lv ing n i trogen, the gas was passed over copper chips at 400°C to remove oxygen. Whenever required , the gases were dr ied in a column of molecular s ieves . For react ions invo lv ing the use of moist gases, the moisture content was contro l l ed by bubbling the gases through a water tower and then through bubble towers containing ice water or saturated s a l t so lut ions maintained at 2 0 6 C . The so lut ions used and the corresponding equil ibrium! water p a r t i a l pressures were; l i t h i u m ch lor ide so lut ion ( 2.6 mm Hg), ice water (4.6 mm Hg), potassium thiocyanate solut ion( 8.2 mm Hg) and ammonium chlor ide so lut ion (12.6 mm Hg), Balance Dry Box Gas Inlet emperature Regulator S p i r a l Immersion Heaters Figure 1. Schematic Diagram of Apparatus. Flow r a t e s were c o n t r o l l e d with c a l i b r a t e d c a p i l l a r y f l o w meters. To o b t a i n gas mixtures, a sepera.,e f l o w meter was used f o r each gas and the gases were mixed i n a v e s s e l s i t u a t e d i n the l i n e immediately before the moisture s a t u r a t i o n . A Chainomatic balance was employed f o r the studic P r o v i s i o n f o r automatic r e c o r d i n g was made by u s i n g two opposed p h o t o e l e c t r i c c e l l s s i t u a t e d behind a v e n t e d vane mounted xat the end o f the balance p o i n t e r . The imbalanced v o l t a g e from^the p h o t o c e l l s was used to d r i v e a Minimax r e c o r d e r . Mechanical l i n k a g e between the r e c o r d e r and the balance was provided by a p a i r of synchro-motors, one o f which was geared to the d r i v e - s h a f t of the r e c o r d e r and the other to the c h a i n d r i v e of the balance. The 'accuracy of the balance, assessed by u s i n g c a l i b r a t e d weights to d r i v e the balance up and down s c a l e , was within -*: 0.3 m i l l i g r a m s . B. SPECIMEN PREPARATION. The l i t h i u m used was obtained i n the form of a c a s t 1 pound ingot from the Foote M i n e r a l Company. The manufacturer's chemical a n a l y s i s w i t h r e s p e c t to potassium and sodium was 340 and 70 ppm r e s p e c t i v e l y . The i n g o t v/as s e c t i o n e d , and p i e c e s were d i e - p r e s s e d i n t o r e c t a n g u l a r b l o cks 2"x l " x 0.6". The b l o c k s were cleaned by immersion i n a methyl hydrate-benzene s o l u t i o n and were then s t o r e d i n a glove-box under an atmosphere of argon. Specimens used i n the experiment were prepared i n the glove-box by c u t t i n g wafers approximately .040 inches i n t h i c k n e s s of rom the r e c t a n g u l a r s l a b s prepared previously,. Piano wire .006 i n c h i n diameter was used f o r the c u t t i n g o p e r a t i o n . C i r c u l a r d i s k s were then cut from the wafers with the a i d of a co r k - b o r e r . The d i s k s were washed i n l i t h i u m -d r i e d benzene before being i n t r o d u c e d i n t o the r e a c t i o n v e s s e l o Co. PROCEDURE The specimens were p o s i t i o n e d i n the basket and lowered i n t o the r e a c t i o n chamber which was charged with the r e a c t i o n gas. A p e r i o d of approximately 2 minutes was r e q u i r e d before the f i r s t , weight r e a d i n g could be taken. Weight gains which occured: d u r i n g t h i s p e r i o d were not recorded. C i r c u l a r d i s k s were used f o r most of the experiments, but f o r runs i n which i t was d e s i r e d a l s o to observe the c o n d i t i o n of the specimen s u r f a c e , r e c t a n g u l a r specimens were used. These specimens were supported from a platinum hook and p e r i o d i c v i s u a l o b s e r v a t i o n s were made by momentarily l i f t i n g the specimen to the upper p a r t ' o f the r e a c t i o n chamber. G e n e r a l l y , r e a c t i m s i n v o l v i n g n i t r o g e n were f o l l o w e d "to completion while those i n v o l v i n g water vapour were f o l l o w e d f o r approximately 24 hours. However, some runs ' were i n t e r r u p t e d i n order to o b t a i n photographs o f the samples. 9 * The react ion products were i d e n t i f i e d with the a id c f an X-ray d i f fractometer . During a n a l y s i s , the specimen surface was protected from further react ion by a l i g h t coat ing of p a r a f f i n wax. Some d i f f r a c t i o n l i n e s from the wax coat ing were always observed but these were eas i ly i d e n t i f i e d 1 . I l l RESULTS FOR REACTIONS IN DRY AND MOIST NITROGEN Ao REACTION WITH DRY NITROGEN l o Results Specimens were reacted with dry nitrogen at 110°Co Weight-time data are tabulated i n Table 1 of Appendix I. A t y p i c a l react ion curve i s shown in Figure 3• The shapes of the react ion curves were c h a r a c t e r i s t i c a l l y a l i k e , i n v o l v i n g a period during which no weight increase was observed followed by a period during which the rate of the react ion increased sharply to a maximum value and then gradual ly decreased to zero o During the i n i t i a l period of zero weight increase , the surface of a specimen, remained untarnished. However, soon a f ter weight increases were recorded massive patches, reddish-brown in colour were' v i s i b l e at corners' and edges of a rectangular specimen. These patches' extended through the thickness of a specimen, and as the reac t ion proceeded they grew r a d i a l l y across the specimen. The surface appearance of a specimen early in a run i s shown in Figure 4. Several runs were made at 110*C, and i n a l l cases n u c l e i were formed p r e f e r e n t i a l l y at corners or at the edges of a specimen. Nucleus formation remote from the edges was never observed. The react ion product was analysed using an X-ray di f fractometer and the r e s u l t s are given in Table 2 of Appendix I A l l ca lcu la ted "d" spacings. correspond to the values given in the A- S. T.. M. f i l e for l i t h i u m n i t r i d e ( L i , Ni ). 11. 2h0 0 50 100 150 200 250 300 Reaction Time (minutes) Figure 3» Reaction Curve for a Rectangular Specimen Heated in Dry Nitrogen at 110°C. 12 F i gure 4« Specimen Reacted in Dry Nitrogen at 110 G. x 1«5 Figure 5. Specimen Reacted i n Moist Nitrogen at 40 C (Pli 0« 4 .6 mm Hg. ). x 1.5 Figure 6^. Reaction I n i t i a t e d i n Moist Nitrogen at 40 G and then continued in Dry Gas. x L 5 13.. .2, Discuss ion of Results for the Reaction in Dry Nitrogen. In a previous study of the react ion between l i t h i u m and dry nitrogen (9), l i t h i u m n i t r i d e was observed to form uniformly over the surface of the specimen. The react ion apparently proceeded by d i f f u s i o n of nitrogen molecules' through a porous, but gradual ly th ickening , l i t h i u m n i t r i d e l a y e r . An incubation period was not observed, but in other respects the react ion curves were s imi lar in shape to those obtained i n the present s tudies . The period of increas ing rate was interpreted as corresponding to the formation of l i t h i u m n i t r i d e over the plane surface of the specimen. The period of gradual ly decreasing rate was interpreted as r e s u l t i n g from the gradual increase in the length of the d i f f u s i o n path for nitrogen molecules as the react ion proceeded. In the present i n v e s t i g a t i o n , l i t h i u m n i t r i d e was observed to form by a process of nucleat ion and growth. Nucleat ion occured p r e f e r e n t i a l l y at the edges and corners of the specimen. The n i t r i d e then formed by l a t e r a l growth across the specimen, and hence the length of the d i f f u s i o n path for ni trogen molecules was constant throughout the durat ion of the r u n . Thus the previous r e s u l t s are d is t inguished from those of the present inves t iga t ion in that , in the former case " nucleat ion " may be regarded as having occurred randomly over the surface of the specimen. This r e s u l t i s s u r p r i s i n g in view of the fact that d i s t i l l e d metal had been employed„ A k i n e t i c ana lys i s of the present re su l t s using weight gain vs . time data alone was impossible, because the 14, . formation of n i t r i d e n u c l e i was random with respect to time. A k i n e t i c ana lys i s would require measurements of r a d i a l growth-ve loc i t ies for i n d i v i d u a l n u c l e i . It was decided to employ -moisture addi t ions to the react ion gas to determine whether or not a uniform surface•react ion would r e s u l t . B . REACTION WITH MOIST.NITROGEN Whereas react ion curves for runs c a r r i e d out in dry ni trogen exhibited a n - i n i t i a l period during which no weight increase was recorded, those for runs in" moist ni trogen rose immediately upon beginning the run. The i n i t i a l weight increases were associated with the formation of a glassy black f i l m over the . en t i re surface of the specimen. X-ray .examination i d e n t i f i e d the f i l m as l i t h i u m hydroxide (Li-OH)., E a r l y during the runs, the react ion curves rose s teeply , corresponding to the appearance- of n i t r i d e n u c l e i at the edges of the specimens. Unlike the case for specimens reacted in dry n i trogen, however, nucleat ion occured a l l along the edges and, for a c i r c u l a r disk led to the formation of a nearly perfect r i n g around the periphery of the specimen. A photograph of a rectangular specimen showing the black hydroxide layer and the l i t h i u m n i t r i d e r i n g about i t s periphery i s shown in Figure 5. Nucleus formation on the plane surfaces of a specimen was commonly observed and is v i s i b l e in Figure 5» 1. The E f f e c t of Reaction Temperature Specimens were reacted with moist ni trogen ( p a r t i a l pressure of water 4 . 6 mm Hg. ) at temperatures 15. from 22 to 70 degrees Centigrade. The r e s u l t s are given i n Tables 2 and 3 of Appendix 1. "Because the t h i c k n e s s of the c i r c u l a r d i s k v a r i e d from specimen to - specimen, the t o t a l weight gains e x h i b i t e d f o r r e a c t i o n s c a r r i e d to completion a l s o d i f f e r e d . Hence, i n order to a l l o w g r a p h i c a l comparison of the r e s u l t s , the curves have been r e - p l o t t e d with the.percentage of the specimen transformed as the o r d i n a t e s a g a i n s t time as a b s c e s s a . ' T y p i c a l curves so obtained are -shown i n F i g u r e s 7 and. 6\ 2... . The E f f e c t , of the Moisture Content of the Reaction Gas. Specimens were r e a c t e d a t 45°C with n i t r o g e n gas at v a r i o u s moisture l e v e l s . These r e s u l t s are gi v e n i n Table 5 o f Appendix 1. • A l s o , some runs were c a r r i e d out i n which moist n i t r o g e n was used to o b t a i n a n e a r l y p e r f e c t r i n g of n i t r i d e around the perimeter of a specimen. Then, d r y n i t r o g e n was f l u s h e d through the system and the specimen was r e a c t e d to co m p l e t i o n • i n dry gas. T h i s procedure was e f f e c t i v e i n ssoapressing the formation of s u r f a c e n u c l e i . A photograph of a r e c t a n g u l a r specimen t r e a t e d i n t h i s manner i s shown i n F i g u r e 6. The r e s u l t s o f these experiments are gi v e n i n Table 9 of Appendix 1 and are shown g r a p h i c a l l y i n F i g u r e 9. 3. E f f e c t of P a r t i a l Pressure of Ni t r o g e n Using a constant moisture content (2.6 mm Hg) and a constant temperature (45°C) specimens were r e a c t e d i n ni t r o g e n - a r g o n gas mixtures a t v a r i o u s n i t r o g e n p a r t i a l p r e s s u r e s ^ The r e s u l t s are given i n Table 4 of Appendix 1 and some r e a c t i o n curves are i n c l u d e d i n F i g u r e 9« 0 50 100 150 200 250 300 Reaction Time (minutes) Figure 7• Reaction Curves for Samples Reacted i n Moist Nitrogen at Various Temperatures. ( Pllgo = 4,6 mm. Hg) 17-50 100 150 200 250 Reaction Time ( minutes ) Figure 8 - Reaction Curves f o r Three Samples Reacted i n Moist Nitrogen at koOC ( P H 2 0 = k.6 mm. Hg ) 18. 19. C . ANALYSIS OF THE RESULTS USING MOIST NITROGEN fb a f i r s t approximation, the re su l t s should conform to the simple geometric model shown in Figure 10. Figure 10 . Schematic Representation ( Ignoring Nucleation Remote from the edges of a Specimen ) of the Formation of Lithium N i t r i d e during a Reaction. A concentric r i n g of l i t h i u m n i t r i d e i s observed to form around the periphery and to grow r a d i a l l y across the specimen. At any p a r t i c u l a r reac t ion temperature, the v e l o c i t y at which the interface advances may be considered to be constant and represents the rate constant for the r e a c t i o n . ( It i s assumed that the i n t e r f a c e v e l o c i t y corresponds to';*the r a d i a l growth v e l o c i t y of an i n d i v i d u a l nucleus ). During-an i n t e r v a l of time t to t+ At the interface advances a d is tance/ i ir g iv ing r i s e to a weight change Aw, where d w = [trr2 - TT(r - d r ) 2 ] h (P Li-^N - / L i ) 2 0 . where h i s the t h i c k n e s s o f the d i s k and / ^ L i ^ N and / - * L i a r e r e s p e c t i v e l y the d e n s i t i e s o f l i t h i u m n i t r i d e and o f l i t h i u m . T h i s e x p r e s s i o n , n e g l e c t i n g square terms i n Ar, reduces t o Aw = 2 7 r r A r x (PlijN - / > L i ) h The d i s t a n c e , r , of the n i t r i d e - m e t a l i n t e r f a c e from the c e n t r e o f t h e d i s k a t any time t i s g i v e n by r - R - Vt where R i.s the d i a m e t e r o f t h e d i s k . S u b s t i t u t i n g t h i s v a l u e -f o r r in the above e q u a t i o n the f o l l o w i n g e x p r e s s i o n f o r the weight increment i n time A t r e s u l t s : Aw = ( 2 7 T R A r - 2 TT v t A r ) ( / ) L i 3 N - y°Li)h whence ( - ^ r ) t = - 2 T f v t ^ £ ) (/°Li3N - / > L i ) h A T or s i n c e J ~ *> V A t ( T ? } t = ( 2 7 r R V " 2 T r V 2 t ) ( / 5 L i 3 N - >PLi)h which, d i v i d e d t h r o u g h by 7 f R 2 h (/^Li^N - /°Li)h g i v e s t r a n s f o r m e d _ v _ a _ ^ A t . t 2 where a = ' and b = Thus the ge o m e t r i c model c o n s i d e r e d above r e q u i r e s t h a t a p l o t o.f the s l o p e s o f the r e a c t i o n c u r v e s a t v a r i o u s t i m e s d u r i n g the r e a c t i o n a g a i n s t time s h o u l d g i v e a s t r a i g h t l i n e . T h i s ' r e q u i r e m e n t was t e s t e d u s i n g e x p e r i m e n t a l data w i t h r e s u l t s as shown i n F i g u r e 11. 21, ,' 116.4 I Reaction Time (minutes) Figure 11. Reaction Rate vs. Reaction Time f o r Samples Reacted at 45°C. 22. The results of runs carried out entirely in moist . nitrogen do not conform to the phenomenological relationship because surface nuclei formed during the experimental runs but were diregarded in the geometric model. However, for runs in which a shift to dry gas was made before surface nuclei could form, the curves rise sharply to a maximum and then decrease at a constant rate. The period of increasing rate corresponds to the period during which a roughly concentric ring of nitride was forming and the results f i t the theoretical relationship increasingly better after the nuclei impinge and then grow inwards-., It is appargnt that from the above considerations that, whereas runs carried out partly in dry nitrogen can be treated adequately in terms of a simple geometric model, further elaboration is required to analyze the reaction curves obtained using moist nitrogen only and for which surface nucleation was involved. 1. Analysis of Results for Runs in Which Surface Nucleation' Was Absent. These runs include those in which a shift was' made from moist to dry gas early during the reaction. The reaction curves were analyzed in terms of the simple geometric model described above. Curves, similar to those shown in Figure 14 were constructed from the reaction curves and the constant 2. 2 b (= 2v / R ) was determined from the linear portions of these graphs..Interface velocities were then calculated and the results are listed in Table 10 of Appendix 1 and are shown graphically in Figure 12. The interface velocities 23. Figure 12. Dependence of Interface V e l o c i t y on Reaction Temperature. 24* rose q u i t e r a p i d l y with i n c r e a s i n g temperature but i t was i m p o s s i b l e to extend the data beyond 50°0 because above t h i s temperature e x t e n s i v e surface n u c l e a t i o n gave r i s e to r e a c t i o n curves which c o u l d not be analyzed i n terms of the geometric model. An A r r e n h i u s p l o t of the l o g a r i t h m s of i n t e r f a c e v e l o c i t i e s a g a i n s t the r e c i p r o c a l s . o f the a b s o l u t e r e a c t i o n temperatures i s shown i n F i g u r e 13. The data conform to a l i n e a r r e l a t i o n and the corresponding a c t i v a t i o n energy i s equal to -7,300 c a l o r i e s per mole of l i t h i u m n i t r i d e formed 2, A n a l y s i s of R e s u l t s of Runs i n Which Surface N u c l e a t i o n was P r e s e n t . Surface n u c l e a t i o n of l i t h i u m n i t r i d e was an important f a c t o r i n a l l the runs c a r r i e d out i n moist n i t r o g e n F i g u r e 8 shows t r a n s f o r m a t i o n - t i m e data f o r three runs c a r r i e d out a t 40°G. In one run the maximum r e a c t i o n r a t e a t t a i n e d was c o n s i d e r a b l y g r e a t e r than i n the other runs, and i t i s c o n s i d e r e d t h a t a g r e a t e r number of s u r f a c e n u c l e i are r e s p o n s i b l e f o r the increased r a t e . D i s c r e p a n c i e s of t h i s type were observed i n d u p l i c a t e runs a t a l l temperatures and s i n c e the number and d i s t r i b u t i o n of s u r f a c e n u c l e i i n each case are unknown, a geometric a n a l y s i s o f the kind used p r e v i o u s l y i s i m p o s s i b l e . In s p i t e of these d i f f i c u l t i e s , however, some q u a n t i t a t i v e data should be o b t a i n a b l e from the t r a n s f o r m a t i o n time curves s i n c e the approximate geometric arrangement o f n u c l e i e a r l y d u r i n g a r e a c t i o n i s known. That i s , n u c l e i form f i r s t a t the p e r i p h e r y of the specimen, and d u r i n g the e a r l y p a r t of the r e a c t i o n most of the weight-gains recorded are due 25-Figure 13. Arrenhius Plots for Interface Velocities. 26. to these n u c l e i rather than to surface n u c l e i which form, l a t e r . Thus i n Figure 8" referred to prev ious ly , the slopes of the reac t ion curves at t h e 20 percent transformation points are approximately equal , even though the curves deviate at l a t e r stages.-Ignoring surface n u c l e i the f r a c t i o n , f, of the sample transformed to n i t r i d e at any given time i s f - 1 ^ where r i s the inner radius of the n i t r i d e r i n g at the time in question and R i s the o r i g i n a l radius of the l i th ium' disk ( = 6 . 6 6 m m . for a l l specimens). D i f f e r e n t i a t i o n of the above expression gives df = _2r _dr_ dt " R 2 dt dr The quantity i s the interface v e l o c i t y , V. t h e n - d f = i & v In order to include the contr ibut ion to the o v e r a l l reac t ion rate of n u c l e i which form at the surface, a correc t ing term would have to be added to the above express ion. However, at the time corresponding to 20 percent of complete transformation the contr ibut ion made by surface n u c l e i i s small and'the equation above can be taken to describe the r e a c t i o n . At th i s point the expression above reduces to V = 3.73 (•^*)f_0 2 m m / m ± n ° 27-Figure 15• E f f e c t of Nitrogen P a r t i a l Pressure on Eeaction V e l o c i t y . 29. Figure 16„ Hypothetical Arrangement of Lithium N i t r i d e for a Sample Reacted P a r t i a l l y to Completion i n Moist Nitrogen. Thus for a l l react ion curves obtained by using wet nitrogen only , slopes were measured at . the point corresponding to 20 percent 'of complete transformation. Interface v e l o c i t i e s were ca lcu la ted and were given i n Tables 3 and 4 of Appendix 1. The r e s u l t s are presented g r a p h i c a l l y in Figures 12, 13, 15 and 16. As shown i n Figure 12 the interface v e l o c i t y rose o r a p i d l y from 25 to 50 C but dropped with further increase in temperature. The a c t i v a t i o n energy for the react ion between 25 and 50°C was 11,500 c a l s . per mode of l i t h i u m n i t r i d e formed. 30. D. DISCUSSION OF RESULTS 1, Factors Inf luencing Nucleat ion Rate The rate o f formation of n i t r i d e n u c l e i depended on several factors inc luding the surface condit ion of the sample, the react ion temperature and the composition of the reac t ion gas. I t has been mentioned previous ly that ni trogen n u c l e i formed p r e f e r e n t i a l l y at s i t e s o f high surface energy such as the edges and corners o f a specimen. For dupl icate runs under the same apparent condit ions the number of surface n u c l e i which formed varied from specimen to specimen. This r e s u l t probably derived from the presence of areas of high surface energy such as scratches at the surface of the specimen. I t appears therefore that the contr ibut ion of surface energies to the thermodynamic free energy required for nuc leat ion was a dominant f a c t o r . That surface energies should exert an important influence i s general ly indicated by a considerat ion of the widely d i f f e r e n t l a t t i c e constants for l i t h i u m n i t r i d e ( cubic; a= 5.50 ), and l i t h i u m ( body-centred-cubic; a= 3«50 ) It i s s i g n i f i c a n t that nucleat ion of l i t h i u m n i t r i d e was promoted by the presence of water vapour i n the react ion gas ( and hence of l i th ium-hydroxide at the surface of the specimen ). The free energy for nucleat ion of l i t h i u m hydroxide on a l i t h i u m surface should involve a r e l a t i v e l y small surface - energy component ( l i t h i u m hydroxide i s tetragonal with a= 3.55 and c=4.34 compared with the body-centred cubic l a t t i c e of l i t h i u m with a = 3.50). I t i s not u n l i k e l y that n i t r i d e nucleat ion was promoted by the presence of l i t h i u m hydroxide by some mechanism involv ing surface energies* However at high react ion temperatures or for high p a r t i a l pressures of water in the react ion gas, n i t r i d e n u c l e i did not form and the l i t h i u m — » • l i thium-hydroxide react ion predominated.(Consideration of the r e l a t i v e chemical free energies involved indicates that the react ion l i t h i u m n i t r i d e plus water —»• l i t h i u m hydroxide should occur. This reac t ion did not proceed under the condit ions studied; however, a pulver ized l i t h i u m n i t r i d e ' sample i n the laboratory atmosphere did react to l i th ium hydroxide over a period of weeks.) 2, Factors in f luenc ing growth ra te . In moist nitrogen two simultaneous react ions were -involved. Lithium n i t r i d e formed by a process of nucleat ion and growth while l i t h i u m hydroxide formed independently at the plane surface of the specimen. The arrangement of the phases during the reac t ion i s shown i n Figure 16. This model i s based upon v i s u a l observation and x-ray d i f f r a c t i o n data and suggests the fo l lowing sequence of reac t ion steps: 1. ) Transport of nitrogen molecules to the gas phase-l i t h i u m hydroxide i n t e r f a c e . 2. ) Adsorption of ni trogen molecules at the i n t e r f a c e . 3. ) D i s soc ia t ion and d i f f u s i o n of nitrogen in the atomic form across the hydroxide l a y e r . 4. ) D i f fus ion through ( porous ) l i t h i u m n i t r i d e or through l i t h i u m metal to the reac t ion I n t e r f a c e . 5. ) Chemical combination at the i n t e r f a c e . It is desired to determine which of these steps is the slowest and hence the rate controlling step for the reaction. Step- 1 normally occurs rapidly and is unlikely to control the reaction rate. The results to be interpreted include: 1. ) The general shape ( Figure 14 ) of the curve showing the dependence of growth velocity on the partial pressure of water vapour in the reaction gas. The curve rose slightly with an increase in water pressure from 2.6 to 4.6 mm-Hg. and then dropped rapidly with further increases in the aqueous tension. Nucleation did not occur in dry gas or at a water pressure of 12.6 mm Hg. 2. ) The general shape ( Figure 12 ) of the curve of reaction velocity against the 5reaction temperature for moist gas. This curve increased rapidly at temperatures from 25 to 50°C but dropped with further increases in temperature. 3. ) The fact that the growth velocities in moist gas were higher than those which obtained when a shift was made to dry gas after in i t i a t i n g the run in moist gas. ( Figure 12 ) 4. ) The dependence ( Figure 15 ) of the curve showing the dependence of growth velocity on the partial pressure of nitrogen. At 45°C and with a partial pressure of water of 2.6 mm Hg., the reaction velocity increased with the square root of nitrogen partial pressure. 3 3 . F i r s t c o n s i d e r the curve i n F i g u r e 14 showing the dependence a t 45°C of the i n t e r f a c e v e l o c i t y on the moisture content of the r e a c t i o n gas. These v e l o c i t i e s decreased r a p i d l y f o r p a r t i a l p ressures of water i n excess of 2 . 6 mm Hg 0 T h i s r e s u l t ' s u g g e s t s t h a t the r a t e of formation of l i t h i u m n i t r i d e i s c o n t r o l l e d by the r a t e of d i f f u s i o n of n i t r o g e n atoms a c r o s s the l i t h i u m hydroxide l a y e r a t the s u r f a c e of the specimen. I t i s shown i n the next s e c t i o n that the r a t e of t h i c k e n i n g of the hydroxide l a y e r s i n c r e a s e s with i n c r e a s i n g p a r t i a l p r e s s u r e s of water vapour. Consequently, f o r a p a r t i c u l a r stage of the l i t h i u m n i t r i d e r e a c t i o n , the length, o f the d i f f u s i o n path f o r n i t r o g e n atoms a c r o s s the l i t h i u m hydroxide b a r r i e r i n c r e a s e s with i n c r e a s i n g water p r e s s u r e s . I f d i f f u s i o n a c r o s s t h i s b a r r i e r i s the r a t e c o n t r o l l i n g step f o r the r e a c t i o n , then the r a t e should decrease with i n c r e a s i n g water pressure as observed. Two other r e s u l t s support the n o t i o n t h a t d i f f u s i o n a c r o s s a l i t h i u m hydroxide b a r r i e r i s r a t e - c o n t r o l l i n g . As i s shown i n F i g u r e 12, i n t e r f a c e v e l o c i t i e s decreased a t temperature above 50°C. T h i s r e s u l t i s considered to d e r i v e from the f a c t t h a t the hydroxide f i l m thickened more r a p i d l y a t h i g h e r temperatures. Again, i n F i g u r e 15 the i n t e r f a c e v e l o c i t y i s shown to depend upon the square r o o t of the n i t r o g e n p a r t i a l p r e s s u r e . T h i s behavior i s c h a r a c t e r i s t i c of cases i n which a diatomic molecule d i s s o c i a t e s on a b s o r p t i o n and then d i f f u s e s i n the atomic form. I t i s l i k e l y that n i t r o g e n would d i f f u s e through l i t h i u m hydroxide i n the atomic form and hence the r e s u l t above conforms to the n o t i o n of a 34. r e a c t i o n c o n t r o l l e d by the r a t e o f d i f f u s i o n a c r o s s a l i t h i u m h y d r o x i d e l a y e r a t the s u r f a c e . On the o t h e r hand some o f the r e s u l t s oppose t h i s c o n c l u s i o n o The growth r a t e s which were observed >/hen a s h i f t , was made to d r y gas a f t e r i n i t i a t i n g the r u n i n m o i s t gas were l o w e r than those which were o b t a i n e d when the r e a c t i o n was c a r r i e d out e n t i r e l y i n m o i s t gas. In the fonac • c a s e , the h y d r o x i d e l a y e r was t h i n n e r and the r a t e s s h o u l d have been much h i g h e r . A p o s s i b l e e x p l a n a t i o n f o r t h i s d i s c r e p a n c y f o l l o w s from a c o n s i d e r a t i o n o f the heat l i b e r a t e d d u r i n g the r e a c t i o n I t i s shown i n the s e c t i o n concerned w i t h a n a l y s i s o f e r r o r s t h a t a c o n s i d e r a b l e amount: o f heat i s l i b e r a t e d and t h a t a s i g n i f i c a n t . d i f f e r e n c e between the measured ( r e a c t i o n gas ) tempe r a t u r e and the a c t u a l r e a c t i o n ( i n t e r f a c e ) temperature c o u l d be e x p e c t e d . I t may be presumed t h a t the t h i c k e r h y d r o x i d e ' l a y e r p r e s e n t when the r e a c t i o n was c a r r i e d out e n t i r e l y i n m o i s t gas p r e s e n t e d an i n c r e a s e d r e s i s t a n c e t o the d i s s i p a t i o n o f heat to the r e a c t i o n gas. T h i s would r e s u l t i n h i g h e r t e m p e r a t u r e s a t the r e a c t i o n i n t e r f a c e and c o r r e s p o n d i n g l y f a s t e r r a t e s . - A d i f f e r e n c e i n te m p e r a t u r e o f 10°C would account f o r the d i f f e r e n c e i n the r a t e s shown i n F i g u r e 12 and t h i s i s not i m p o s s i b l e . E x p e r i m e n t a l a c t i v a t i o n e n e r g i e s o f 7,300 and 11,300 c a l s were obse r v e d a c c o r d i n g t o whether the runs were made p a r t i a l l y i n d r y gas or e n t i r e l y i n m o i s t gas. In the former case the t h i c k n e s s o f the h y d r o x i d e l a y e r was a p p r o x i m a t e l y the same r e g a r d l e s s o f the r e a c t i o n t e m p e r a t u r e 3 5-. ( the s h i f t t o d r y gas was made a t a time c o r r e s p o n d i n g t o a we i g h t g a i n o f 5 p e r c e n t o f the t o t a l e x p e c t ed i n c r e a s e ). However f o r specimens r e a c t e d e n t i r e l y in m o i s t gas the t h i c k n e s s o f the h y d r o x i d e f i l m i n c r e a s e d w i t h the r e a c t i o n t e m p e r a t u r e o The r e s u l t a n t i n c r e a s e i n the d i f f u s i o n p a t h f o r n i t r o g e n atoms a c r o s s the b a r r i e r thus a c c o u n t s f o r the i n c r e a s e d a c t i v a t i o n energy. E . SOURCES OF ERROR The g e o m e t r i c model employed in o r d e r t o determine i n t e r f a c e v e l o c i t i e s was an approximate r e p r e s e n t a t i o n o f the a c t u a l arrangement o f l i t h i u m n i t r i d e n u c l e i d u r i n g the r e a c t i o n . V a r i a t i o n s i n the e x p e r i m e n t a l v a l u e s must t h e r e f o r e be e x p e c t e d but r e a s o n a b l e r e p r o d u c i b i l i t y was r e a l i z e d . F o r example, the c a l c u l a t e d i n t e r f a c e v e l o c i t i e s f o r f o u r P o runs i n m o i s t ( H2O = 4»6 mm Hg.) n i t r o g e n a t 40 C were 0.010, 0.010, 0.0090, and 0.00&7 mm./min. Another source o f e r r o r r e s u l t e d from the w e i g h t i n c r e a s e s a s s o c i a t e d w i t h the f o r m a t i o n o f l i t h i u m h y d r o x i d e over the s u r f a c e o f t h e specimen. T h i s c o n t r i b u t i o n t o the o v e r a l l w e i g ht change was i g n o r e d when c a l c u l a t i n g i n t e r f a c e v e l o c i t i e s . However, a s i m p l e c a l c u l a t i o n ( i n terms o f the measured r a t e s f o r the h y d r o x i d e r e a c t i o n as d e s c r i b e d i n the next s e c t i o n ) shows t h a t the c a l c u l a t e d growth v e l o c i t i e s f o r the n i t r i d e r e a c t i o n a r e i n e r r o r by l e s s t h a n 5 p e r c e n t due to t h i s f a c t o r . A f u r t h e r source o f e r r o r becomes a p p a r e n t by a c o n s i d e r a t i o n o f t h e r a t e a t which h e a t i s e v o l v e d d u r i n g the r e a c t i o n . The heat l i b e r a t e d during the react ion 3 L i + 5 —*- Li-^N i s 1 5 . 7 k ca ls per mole of l i t h i u m . For a standard specimen 0 . 1 cm. in thickness i t i s . r e a d i l y shown that , a t - the time for which the reac t ion i s 20 percent complete, the rate at which heat i s l i b e r a t e d i s given by Q ( ca l s /mln ). = 4 4 5 V (ca l s /min ) where V i s the interface v e l o c i t y expressed in cm/min. For the react ion in moist ( ^H20 - 4 . 6 mm Hg. ) ni trogen the react ion velocities;; at 25 and 45°C were respec t ive ly .0011 and . .0042.. cm/min. Then during one minute the heats l i b e r a t e d for the react ions at 25 and 45°C are respec t ive ly 0.49 and 1.8*7 cals;.. These amounts :-of heat i f d i s t r i b u t e d without loss throughout the unreacted•port ion of the specimen ( . spec i f i c heat of l i t h i u m metal - 0 . 9 6 cals/gram ) are s u f f i c i e n t to cause a temperature increase of 9 or 34 degrees Centigrade r e s p e c t i v e l y . Such d r a s t i c temperature increases would not a c t u a l l y occur because most of the react ion heat would be transferred to the gas. However, the react ion occurs at an interface of r e l a t i v e l y small area and i t i s l i k e l y that the temperature increase at the interface would be considerable . In a l l the experiments therefore , the ac tua l react ion temperatures ( at the l i t h i u m - l i t h i u m n i t r i d e interface ) were greater by unknown amounts than the measured temperature ( i e . the temperature of the react ion gas ). This source of error could d r a s t i c a l l y influence the shape of the react ion rate vs . " temperature " curve as suggested in the d i s cus s ion . 3 7 . F . CONCLUSIONS The react ion of l i t h i u m with nitrogen proceeds with nucleat ion and growth of l i t h i u m n i t r i d e . The presence of moisture in the react ion gas promotes nucleus formation but a lso leads to the formation of l i t h i u m hydroxide at the plane surface of the specimen. The r e s u l t s suggest that the rate of n i t r i d e formation is contro l l ed by d i f f u s i o n of nitrogen atoms across the l i t h i u m hydroxide l a y e r . IV REACTION WITH WATER VAPOUR A. . REACTION WITH DRY AND MOIST OXYGEN A specimen heated i n dry oxygen at 40°C exhibited! no increase i n weight over a period of 16 hours. In agreement with t h i s observation, i t i s reported that l i t h i u m does not react with dry oxygen below 100°C although i t reacts rapidly at higher temperatures. (5) I t i s shown l a t e r that, so far as X-ray d i f f r a c t i o n data could show l i t h i u m oxide did not form in moist oxygen at temperatures from 22-42°C, but that, instead, the reaction product was l i t h i u m hydroxide. Accordingly, runs carried out in moist oxygen are reported below as reactions with water vapour and oxygen i s classed with argon and helium as an inert c a r r i e r gas. B. REACTION WITH WATER VAPOUR 1. General Characteristics of the Reaction Some t y p i c a l reaction curves obtained using moist ( ^^0 = 4.6 mm Hg. ) oxygen at temperatures from 2 5 to 40°C are shown i n Figure 17. A comparison of the reaction rates in moist oxygen, argon and helium i s made i n Figure 18. It i s apparent from these curves that the reaction proceeded i n three d i s t i n c t stages:. 1. ) an i n i t i a l stage, i n duration l a s t i n g from 3 to 4 hours and i n which the reaction rate was approximately constant. 2. ) an intermediate stage during which, over a period of 50 o Reaction Time (minutes) Figure 18. Reaction Curves f o r Specimens Reacted i n Moist Gases a t 35°C ( PR2O = k-6 mm. Hg* ; Specimen Area = 2,79 on?*)-41.. 1 to 4 hours depending on the temperature, the reaction rate increased continuously. 3.) a t h i r d stage during which the reaction proceeded at a constant rate approximately l | times that of the i n i t i a l stage. Visual examination of the specimens revealed a c h a r a c t e r i s t i c sequence of changes i n the appearance of the specimens which corresponded with the observed changes in reaction rates. Some runs were interrupted i n order to obtain photographs of the samples and these are shown i n Figures 19a-e. During the i n i t i a l stage of approximately constant rate, the specimens acquired a black glassy tarnish (Figure 14a) reminiscent cf the surface f i l m which has been observed to form i n moist-nitrogen. At a time corresponding approximately to the commencement of the intermediate ( rate-increasing ) stage, a white reaction product formed on the surface of the specimen. This product often formed f i r s t at the edges of the specimen and grew l a t e r a l l y across the surface. Photographs are shown in Figures 19 b and d. The f i n a l stage of constant rate commenced when the entire surface was covered with the white product ( Figure 14c ) which then thickened uniformly over the surface as the reaction proceeded. The specimen swelled s l i g h t l y during t h i s period and the appearance of a specimen oxidized to completion i s shown i n Figure 19e. The grea.tly enlarged size of the specimen at t h i s stage i s to be noted. X-ray d i f f r a c t i o n patterns were obtained of the reaction f i l m at various stages of the reaction and these Reaction Time Figure 19* Changes i n Surface Appearance of Rectangular and Ci r c u l a r Specimens i n Relation to a Typical Reaction Curve. 4 3 . r e s u l t s are given in Tables 5 and 6 of Appendix 1 1 . For the black f i l m c h a r a c t e r i s t i c of ear ly stages of the r e a c t i o n , the ca lculated d spacings for each of the d i f f r a c t i o n l i n e s compared c lose ly with those given for l i t h i u m hydroxide ( L i O E ) in the A. .S.T .M.card f i l e s . The white layer which was present at advanced stages gave two sets of d i f f r a c t i o n l i n e s corresponding to l i t h i u m hydroxide ( L i OH ) and l i t h i u m monohydrate ( LiOH • H2O ) . A sample reacted to completion at 35°C ( P H 2 0 = 8 . 2 mm. ) was e n t i r e l y LiOH * H 20 2 . Comparison of Oxygen, Argon and Helium as C a r r i e r Gases. Although the i n i t i a l react ion rates -for runs carr i ed out in moist argon or oxygen were very nearly constant, those for helium were more rapid at f i r s t and decreased s l i g h t l y as the react ion proceeded. It i s considered that , some separation of helium and water occured which resulted i n increased p a r t i a l pressures of water in the react ion tube. The r e s u l t s ' f o r a l l runs carr i ed out in moist helium are included i n Table 3 of Appendix 11 but are considered untrustworthy and are not included in the d iscuss ion of r e s u l t s . 3 . E f f e c t of Temperature. Lithium specimens in the form of c i r c u l a r disks were reacted with moist oxygen at temperatures from 22-42°C and the re su l t s are summarized in Table 2 of Appendix 1 1 . Graphs ( Figure 20 ) of the logarithms of the rate constants against the r e c i p r o c a l of the absolute react ion temperature gave s t r a i g h t l i n e s in accordance with the.. Arrhenius r e l a t i o n s h i p . The a c t i v a t i o n energies for the react ion were respec t ive ly 11,700 and 7,700 c a l s . for the Vapour Pressure. 46.. i n i t i a l and f i n a l stages r e s p e c t i v e l y . 4o E f f ec t of the P a r t i a l . Pressure of Water Vapour Samples were reacted at 35°C in .argon gas saturated to give moisture l e v e l s of 2 .6, 4 . 6 , S.2 and 12.6 mm Hg. A l l react ions displayed, the three c h a r a c t e r i s t i c stages as before. The reac t ion rate constants were determined and a graph showing- the dependence of these rates on the p a r t i a l pressures of water i s shown in Figure 21. In another run, a specimen was reacted in moist (4 .6 mm. Hg.) oxygen at 35°C u n t i l the white product c h a r a c t e r i s t i c of an advanced reac t ion had formed. A s h i f t was then made to dry oxygen. The rate dropped to zero thus i n d i c a t i n g that l i t h i u m oxide would not form under these condi t ions . Co DISCUSSION OF RESULTS 1. General Considerations It was mentioned e a r l i e r that the white product which f i r s t appeared during the "intermediate" stage of the r e a c t i o n , formed f i r s t at the edges of the specimen and then spread inwards across the face . This - behavior suggests that a r e c r y s t a l l i z a t i o n process i s involved. The occurence of r e c r y s t a l l i z a t i o n implies :that the i n i t i a l f i l m was in a state thermodynamically l e ss stable than the r e c r y s t a l l i z e d product. From a comparison of the l a t t i c e constants of l i t h i u m hydroxide ( te tragonal; c = 4".34 A, a = 3 .55 A ) and l i t h i u m .( cubic; a = 3 • 50 A ) i t i s at l e a s t poss ible that the i n i t i a l f i l m was coherent with the underlying 47. meta l l i c l a t t i c e . Such a f i l m would necessar i ly be in a state of l a t e r a l compression and as the f i l m thickened the gradual increase in s t r a i n energy might provide a d r i v i n g force for r e c r y s t a l l i z a t i o n . • Another important r e s u l t was that , whereas the i n i t i a l black f i l m was e n t i r e l y l i t h i u m hydroxide ( LiOH ), the r e c r y s t a l l i z a t i o n layer incorporatedamounts of l i t h i u m monohydrate ( LiOH°H20 ). A considerable increase in the compressive stresses ac t ing on the l i t h i u m hydroxide f i l m should accompany hydration and these stresses may have provided an a d d i t i o n a l . d r i v i n g force for r e c r y s t a l l i z a t i o n . Although the d i s p o s i t i o n of l i t h i u m hydroxide and monohydrate in the r e c r y s t a l l i z e d layer could not be in ferred from the X-ray d i f f r a c t i o n data obtained, i t i s reasonable to suppose that a concentration gradient with respect to water of hydration existed such that the outer port ion of the layer was e s s e n t i a l l y l i t h i u m monohydrate while the' inner port ion was l i t h i u m hydroxide. At completion of a react ion ( at l eas t for a p a r t i a l pressure of water of 12.6 mm ) the ent ire sample had transformed to l i t h i u m monohydrate. The r e l a t i v e magnitude of the react ion rates at advanced stages can be explained from the above cons iderat ions . The increase in weight due to hydration of the hydroxide f i l m may be considered to proceed at a constant rate which i s superimposed upon the i n i t i a l r a t e . Then the new rate would be approximately 2 times the i n i t i a l r a t e . In Tables 2 and 4 of Appendix 11 i t i s shown that the r a t i o s of f i n a l 4 8 . to i n i t i a l reac t ion rate constants vary from 1 . 3 - 1 . 9 , the higher values being associated with low react ion temperatures. The only exceptional r e s u l t i s the value of 3 . 1 which obtained at 3 5 ° C and at a water p a r t i a l pressure of 2 . 6 mm Hg. The l a t t e r r e s u l t was obtained in the region of extreme pressuredtpendence and i t s s ign i f i cance i s not understood. 2 . The Ef fec t of the P a r t i a l Pressure of Water in the Reaction Gas. In a previous inves t iga t ion concerned with the reac t ion of l i t h i u m with water vapour ( 4 ) i t was reported that the rate constant for the reac t ion ( the i n i t i a l rate constant only was determined ) was pressure independent at moisture l e v e l s from 2 2 - 5 5 mm Hg. The rates increased with pressure above 5 5 mm Hg but a lower l i m i t to the pressure range was not encountered, the lowest pressure invest igated being 2 2 mm Hg. For the present study, the dependence of the react ion rate constants on the p a r t i a l pressure of water in the react ion gas i s shown in Figure 2 1 . The rate constants for both the i n i t i a l and f i n a l stages of oxidat ion increased r a p i d l y with pressure in the range 2 . 6 - 4 . 6 mm Hg but with further increases in pressure the rate constants appear to increase according to a l i n e a r r e l a t i o n s h i p . 3 . Suggested Mechanism It i s desired to determine the rate c o n t r o l l i n g step for the r e a c t i o n . Ear ly during the react ion the consecutive steps involved should include: 1.) transport of water molecules to the l i t h i u m hydroxide-gas i n t e r f a c e . 49 o 2. ) adsorption at the i n t e r f a c e . 3. ) d i f f u s i o n through the hydroxide l a y e r . 4. ) adsorption at and react ion with l i th ium at the in ter face . Later during the react ion another step, that of l i t h i u m hydroxide to l i t h i u m monohydrate, must be considered but th i s step may be assumed to proceed independently. Now, i f step (1) above were rate c o n t r o l l i n g , then the rate of the reac t ion would be contro l l ed by the rate of impingement of water molecules onto the specimen surface and a l inear^rate law would be expected to pers i s t throughout the r e a c t i o n . However since the rate ac tua l ly increased at a l a t e r stage, i t must be concluded that step (1) i s not r a t e -c o n t r o l l i n g . It i s l i k e l y that step (3) above may also be el iminated as r a t e - c o n t r o l l i n g . It i s reported (4) that the reac t ion of l i t h i u m with water vapour in the pressure range 22-100 mm. proceeds according to a logarithmic rate law and, moreover, that the rates were pressure-independent in the • range 22-55 mm. Hg. These r e s u l t s were interpreted in terms of a d i f f u s i o n - c o n t r o l l e d reac t ion a n d , i f th i s in t erpre ta t ion i s co'rrect, the present r e s u l t s at low p a r t i a l pressures of water preclude d i f f u s i o n through a hydroxide f i l m as the r a t e - c o n t r o l l i n g step for the r e a c t i o n . It should be pointed out that the previous invest igators followed the react ion rates by measuring the increase in pressure in a s ta t i c system due to hydrogen evolved during the react ion LitH2P —*• LiOH+ gHl, Although the inves t iga t ion was concerned only with the ear ly stages of the reac t ion during which, according to the present i 5.0). r e s u l t s , n o l i t h i u m m o n o h y d r a t e w a s f o r m e d i t i s c l e a r +-hat t h e m e t h o d u s e d c o u l d n o t h a v e s e n s e d t h a t t h e r e a c t i o n L i O H + H2O — > L i O H w a s o c c u r i n g s i m u l t a n e o u s l y . T h e a u t h o r s s t a t e t h a t " w i t h t h e a p p e a r a n c e o f t h e w h i t e p r o d u c t , t h e r a t e o f t h e - • r e a c t i o n b e c o m e s c o m p l e t e l y u n p r e d i c t a b l e T h i s o b s e r v a t i o n i s s i g n i f i c a n t b e c a u s e n o s u c h u n p r e d i c t a b i l i t y w a s e n c o u n t e r e d i n t h e p r e s e n t s t u d i e s . I t n o w s e e m s l i k e l y t h a t a n e t w o r k o f c r a c k s d e v e l o p e d i n t h e f i l m d u r i n g r e c r y s t a l l i z a t i o n . I f d i f f u s i o n a c r o s s t h e f i l m w a s r a t e -c o n t r o l l i n g t h e n t h e d e v e l o p m e n t o f c r a c k s o n t h e f i l m w o u l d c e r t a i n l y d i s r u p t t h e r e a c t i o n r a t e a s o b s e r v e d p r e v i o u s l y . T h a t n o d i s r u p t i o n w a s o b s e r v e d o f f e r s f u r t h e r s u p p o r t t o t h e c o n c l u s i o n t h a t d i f f u s i o n w a s n o t r a t e - c o n t r o l l i n g a t t h e l o w w a t e r l e v e l s e m p l o y e d i n t h e p r e s e n t i n v e s t i g a t i o n . R e f e r r i n g b a c k a g a i n t o t h e r e a c t i o n s t e p s i n v o l v e d , i t s e e m s l i k e l y t h a t , b e s i d e s s t e p s (1) a n d ( 3 ) , s t e p (4) i s n o t r a t e - c o n t r o l l i n g b e c a u s e a c t u a l c h e m i c a l r e a c t i o n s n o r m a l l y p r o c e e d r a p i d l y . • I t ' i s p r o b a b l e t h e n t h a t t h e r a t e o f t h e r e a c t i o n w a s l i m i t e d b y t h e r a t e o f u p t a k e o f w a t e r m o l e c u l e s a t t h e s u r f a c e o f t h e s p e c i m e n . T h e r e a c t i o n r a t e v s . w a t e r p a r t i a l p r e s s u r e c u r v e g i v e s g e n e r a l s u p p o r t t o t h i s n o t i o n . I t c a n b e s h o w n ( £ ) , u s i n g t h e L a n g m u i r A d s o r p t i o n I s o t h e r m t h a t t h e r a t e o f u p t a k e o f g a s m o l e c u l e s ( w h i c h t h e n d i f f u s e i n t o t h e b o d y o f t h e m a t e r i a l ) d e p e n d s o n t h e e q u i l i b r i u m b e t w e e m t h e r a t e a t w h i c h g a s m o l e c u l e s c o n d e n s e o n t o t h e s u r f a c e a n d t h e r a t e s o f e v a p o r a t i o n a w a y f r o m t h e s u r f a c e ( e i t h e r b a c k t o t h e g a s p h a s e o r i n t o t h e b o d y o f t h e m a t e r i a l ) . A t 51.-e q u i l i b r i u m the f r a c t i o n , Q , o f the s u r f a c e c o v e r e d w i t h w ater m o l e c u l e s i s g i v e n by the e x p r e s s i o n 0 6 u e -- v+»<:u where u i s the number o f m o l e c u l e s c&tmilfciiBg; u n i t a r e a o f s u r f a c e per second, c*C i s the p r o p o r t i o n o f th e s e m o l e c u l e s which adhere ( the accomodation c o e f f i c i e n t ) and v i s a c o n s t a n t f o r a g i v e n gas and s u r f a c e . The r a t e , u , a t which m o l e c u l e s s t r i k e the s u r f a c e i s d i r e c t l y p r o p o r t i o n a l t o the gas p r e s s u r e . Hence, the e x p r e s s i o n above may be w r i t t e n << P e = k which has the l i m i t s v+<< P Q - k —<^=. p a t low p r e s s u r e s v o r Q - k a t h i g h p r e s s u r e s . That i s , a t low t e m p e r a t u r e s f o r which the specimen s u r f a c e i s o n l y s p a r s e l y c o v e r e d by m o l e c u l e s t h e p r o p o r t i o n o f t h e s u r f a c e a c t u a l l y c o v e r e d ( and hence the r e a c t i o n r a t e ) i s d i r e c t l y p r o p o r t i o n a l t o the gas p r e s s u r e . The r e a c t i o n between l i t h i u m and water vapour was p r e s s u r e dependent a t p a r t i a l p r e s s u r e s from 4.6 t o 12.6 mm. Hg. At h i g h e r gas p r e s s u r e s the specimen s u r f a c e i s c o m p l e t e l y c o v e r e d by water m o l e c u l e s and the r e a c t i o n r a t e becomes independent o f gas p r e s s u r e as obse r v e d by D e a l and Svec f o r p a r t i a l p r e s s u r e s o f wa t e r above 22 mm. Hg. However, c o n s i d e r a t i o n s above do not a c c o u n t f o r 52. the fac t that water molecules were ava i lab le in s u f f i c i e n t amounts to al low the formation of l i t h i u m monohydrate. In-order to account for th i s r e s u l t i t i s necessary to presume that the accomodation coe f f i c i en t , ° < , increases up< n. r e c r y s t a l l i z a t i o n of the l i t h i u m hydroxide f i l m to alloxv a greater number of water molecules to condense at the surface . The o v e r a l l react ion rate then increases with the formation of l i t h i u m monohydrate at the specimen surface. D. SOURCES OF ERROR 1. E r r o r s due to V a r i a t i o n s in Surface Condi t ion . The geometric areas of the samples were used for c a l c u l a t i n g rate constants. Although the geometric areas were l e ss then true areas by an unknown amount' ( the roughness factor ), the r e s u l t s were reproducible and i t i s assumed that a l l specimens possessed the same roughness f a c t o r . Then, although th i s source of error a f fects the values of the measured rate constants, i t would not a f fec t the experimental a c t i v a t i o n energies . 2. Error in Temperature Measurement due to Liberated Reaction Heats. The heat l i b e r a t e d during the react ion Li+OH —?LiOH i s 116.4 k c a l s . per mole of l i t h i u m reacted. Then, for the react ion at 35°C ( P H 2 0 = 4 .6 mm. Hg. ) heat i s l i b e r a t e d at the rate of 0.2 c a l s . / m i n . This amount of heat i f d i s t r i b u t e d without los s throughout the specimen i s s u f f i c i e n t to cause a temperature increase of approximately 3 ° C / m i n . but most of the heat would be d i s s ipated by transfer to the c a r r i e r gas. 53 A l s o , since the area of the surface interface i s r e l a t i v e l y l a r g e , the- di f ference between the measured temperature nd the ac tua l temperature would c e r t a i n l y be l e ss than that for the l i t h i u m n i t r i d e react ion - discussed previov l y „ 3. Zero Point E r r o r In a l l cases, a zero point error was present because a few minutes elapsed between the time of i n i t i a t i n g the run.and the time at which the f i r s t weight reading was taken. This error does not a f fec t the measured values for the rate constants . 4. Errors due to Transport of Water Molecules to the L i th ium-Hydroxide Gas Interface . It i s i n s t r u c t i v e to consider the p o s s i b i l i t y that reac t ion rates could have been influenced by transport of water molecules from the gas phase to the specimen. The fas tes t rates recorded involved the consumption of approximately 0.3 mg. water per minute. For a water p a r t i a l pressure .of 4.6 mm. Hg." t h i s amount of water i s contained in a volume of approximately 60 cc . of the reac t ion gas. However,reaction gas entered the system at a rate of 150 c c . / m i n . and t h i s was probably s u f f i c i e n t to ensure against deplet ion of water i n the system. E . CONCLUSIONS  The reac t ion of l i t h i u m with water vapour proceeds in three d i s t i n c t stages. I n i t i a l l y , a l i t h i u m hydroxide f i l m forms which i s coherent with the underly ing l i t h i u m l a t t i c e . At the low 54. p a r t i a l pressures used in the inves t iga t ion the re su l t s suggest that adsorpt ion of water i s r a t e - c o n t r o l l i n g . At water p a r t i a l pressures higher than 2 2 mm. Hg. the r a t e , according to a previous inves t iga t ion (4), becomes pressure independent and the rate i s contro l l ed by d i f f u s i o n across the l i t h i u m hydroxide l a y e r . As the react ion proceeds, s u f f i c i e n t s t r a i n energy i s b u i l t up to provide a d r i v i n g force for r e c r y s t a l l i z a t i o n of the f i l m . During r e c r y s t a l l i z a t i o n the f i l m develops a network of cracks . Simultaneously with r e c r y s t a l l i z a t i o n , the outer port ions of the reac t ion layer undergo p a r t i a l hydrat ion to l i t h i u m monohydrate. The increased weight gains associated with water-of-hydrat ion are superimposed upon those due to r e a c t i o n to l i t h i u m hydroxide and the o v e r a l l rate of the r e a c t i o n increases by approximately 1| times the i n i t i a l r a t e . This was not observed by the previous inves t igators (4) because of the i n s e n s i t i v i t y of the manometric method used to hydrat ion of the f i l m . ' ¥ BIBLIOGRAPHY 1. P i l l i n g and Bedworth, J . I n s t i t u t e of Metals, V o l . 29 529 ( 1923 ) . 2. A..R. Evans, J Electrochem. S o c , 91, 547 ( 1947 ). 3. Gregg and Jepson, j . i n s t i t u t e of Metals, 91, 351 (1959 )• 4. B.E. Deal and H.J. Svec, J.Am. Chem. S o c , 75, 6173-5 ( 1953 ) . 5o Foote M i n e r a l Company B u l l e t i n . 6. S.. Yamaguti, Nature, 145, 742 ( 1940 ). 7. A.I. Belyaev, L.A. Firanova and I.N. Pomerantsev, paper reviewed i n Chemical A b s t r a c t s , 50, 155400-1 ( 1956 ),. 8. K.J. L a i d l e r , Chemical K i n e t i c s , f i r s t e d i t i o n , McGraw-Hill, 1950. p. 177. 9. V/. Frankenburger, F. Electrochem., 32, 481-91 ( 1926 ). VI APPENDICES APPENDIX 1 Table 1. Reaction Rates with Dry Nitrogen at 110°C, (Rectangular Specimens; 1= l.OOy w= 0.500" ). Reaction Time Weight Gain of Samples (minutes) ( mg. ) 1 2 1 0 0 0 0 15 0 0.2 0 30 0 0..6 . 0 45 0 1-5 2,2 60 1..9 3 ..0 3.6 75 4.7 5 . 3 5.2 90 7.-5 9.6 7.5 105 10.8 14.6 I0:..4 120 15..4 24.8 14.2 135 21.2 37.0 18 .7 150 27.4 55.5 24.5 165 35.2 73.-8 31..7 180 43. a 107.7 39.-9 195 54.1 144 „3> 49.0 210 65..0, 59..0 225 68,2 69.9 240 80.5 2 55 90.0 270 97.-3 235 104 ..3 300 110.9 315 116.5 • Table 2 '' v,':•*'., Reaction Rates•of,Circular Lithium'Disks with Moist Nitrogen ( .Partial Pressure o f Water = 4-6 mm. ).. Temp. React. Percentage of the Sample Time.mins. .' Transformed '. . 2 5 ° C • '. 30°C 35°C •' 3 5 ° C ' ; 35°C o •0 o; •'• 0 : 0 • : 0 ' 15 • . • 0.9 •• • 0..2 ' 0.8 . , • ' Q)„2 ' , : 0 . 2 30 . 1.5 •; 0.6 : 0.5 0.8 0...7 "45 1.4 •• , 1.1 . . 1.9 '• • ' 1.4-60 2..7 . 2,4 ' 1 . 6 •3.7 2..5 75 '•• • 3.1 • • 3 .3, 2 ..3 , 7.-8 . . , '3 .8 9.0 . ' 3.5 , 4.5 • 3.4 •. 15..2 .' 6,7 105. 3 ..9 ; 6.5 26.4' .11.6 120. 4.4 . 9 ..2 ' ' 7 . 9 •: • '42,0 18,9. 135 4 »<8 • 1 3 - 9 12.1 61 o.0 27.4 150 • 5.2 , • • .' 20.. 8 18 ...5 • 81. ..0 ' 40,.l. 1165 5..6 31.-2 2 7 . 3 95..1 5 2 , 7 130 • . 5.9 , 43.0 . ' 3 7 . 8 99.5 •. 64 »77 195 . 5 7 . 2 : 50.0 • 99 ..8 ' 77.7 210; 6.6 7 2..2. 65..2 100 . 88 .A 2 2 5 6.9 85..2 77.2 96 d 240 7.2 93 ..4 '• 89.. 5 99.-9 2 5 5 7..5 ' 9 8..6 9 7 . 6 270 7 . 7 99.8 99.6 285 100.0 99.8 300 8.4 100 315 8.8? 330 9 o2. 345 9.7 465 21.2 480' 24 .9 495 30,4 510 37.3 Table 2 (continued) Temp. React. Percentage of the Specimen Time . mins. Transformed 40°C 40J°C 40°C • •' 45°C 45°C 50°C •o 0 0 0 0 0 0 15 0.4 . 0.6 0.2 0..7 • 0.2 30 0.8 •' 1.6 2.5 . 2.3 2.5 2.5 45 2.5 3.0 5.6 V .7.3 6.4 7.8 60 6.1 .5.5 ' 12.2 .,• 17.7. 15.5 22.5 65 •30.0 70 20.9 25.6 . 38.5 75 13.3 10.1 26.1 36.6 31.2 48.0 80 31.8 36.4 57.9 35 37.6 42.3 68.2 90 25.4 19.1 43 .4 65.0 47.3 77.7 95 48.9 74.7 53 .0 86.9 100 54.4 84.9 53.1 94.4 105 39.5 35.0 60.0 91.0 63.3 98.2 110 65.4 95.5 63.5 99.6 115 70.8 98.4 73.5 99.8 120 53.7 58.0 76.2 99.4 73.1 100 125 81.2 99.8 32.6 100 130 86.1 87.0 13 5 67.2 83.4 100 90.5 140 94.0 93.6 145 97.0 96.1 150 79.1 97.6 98.9 98.2 155 99.6 99.1 160 99.8 99.7 165 88.6 99.8 100 99.9 180 96.8 100 100 195 99.5 210 99.8 225 100 59 Table. 3 Analysis , of Results of Runs Carr ied out in Nitrogen at a Water Level of 4 . 6 mm. Hg, T°C d f 20 dT * u V (mm./mini.) -0033 55 25 ..ooao .0112 .003300 30) .00 57/ .004+8$ .0213; -0.179 ..003 246 35 .0063; ..0065 ..0067 .0067// .02.35 .0242 .02 50) .02.50) ..003194+ 40 .010 0) ..0100 ..0090 -0087# .0373 .0373 -0336 ..032 5 ,.003144 45 .0110) -011? -0116 -0410) .0436 -043-2 ..003100) 50 .0150 .0540 -0560 -00304.9 55 .0132// ..0.12.6// ..0490 .04-72! ..003007 60 -0117# .0438 ..00291-8 70 .00645 .0.2 50 $ Values taken d i r e c t l y from Curves Obtained on Recording Balance. 60 Table 4 Effect of Nitrogen Pressure on Reaction Velocity at 45°C •( Moisture Level = 2.6 mm. Hg.; Values, taken directly from Curves Obtained on Recording Balance ). i Nitrogen Partial (, PN 2 ) V ( mm ./min.. ). Pressure 1 atom 1 ..0393 0..77 0>38 ..0327 0.73 0.85 .0310 0.64 0.80 .0311 0;. 50 0 ..71 .02:61 0.31 0.56 .0209 0.20 0.45 .0149 Table 5 Effect of Water Partial Pressure on Reaction Velocity in Nitrogen at 45°C ( Values taken directly from Curves Obtained in Recording Balance ). Partial Pressure of Water (mm.) V" ( mm./min. ) 0 No Nucleation 2.6 .0393 4.6 .0427 8.2 ..0134 12.6 No Nucleation 61.. Table 6 E f f e c t of Temperature and Gas Composition on Nu c l e a t i o n Rate ( expressed as the Time required f o r the Reaction to Proceed to 20 percent of completion ). a. . E f f e c t of Temperature ( P N 2 = 1 atm.; , ^ HgO = 4.6 mm. ). T°C t ( minutes ) 2 5 460 30 148, 160, 97 35 123, 154, 120 40 9 2 , 68, 84, 85 45 63, 65„ 63 50 58 55 62, 62 60 55 70 78 110 No Nucleatiom b. . E f f e c t of Moisture Content ( P N 2 = 1 atm.; T = 45°C ) PH 2Q (mm.) t ( minutes ) 0 NJO N u c l e a t i o n 2.6 48 4-6 63, 65, 63 8.2 13 8 12 ..6 No Nu c l e a t i o n P Co E f f e c t of Nitrogen P a r t i a l Pressure ( H 20 = 2.6 mm.; T = 45°C ) t ( minutes ) PM 2 (mm.) 1 63 0..77 58 0..73 52 0.64 56 0.50 78 0.31 105 0.20 175 62. Table 7 Reaction Rates of C i r c u l a r and Rectangular Specimens i n Moist Nitrogen Gas at 30°C (Gas saturated to a moisture content of 4.6 mm. Hg.) Reaction Time Percentage of (minutes) Sample Transformed C i r c u l a r Rectangular 0 0 0 15 0.2 0.7 30 0.6 1.3 45 1.4 2.4 60 2.4 5.0 75 3.3 8.9 90 4.5 13.9 105 6,.5 13.9 120 9.2 24.2! 13 5 13.9 30.3 150 20.8 38.7 165 31.2 46.5 180 43.0 56.1 195 57.2 66.5 210 72.2 76.9 2 2 5 8 5 . 2 86.4 240 93.4 93.2 255 98.6 98.1 270 99 . 8 99.6 285 100 99.9 300 100 Rectangular Specimen: l e n g t h = 1.00" ; width = 0.598 C i r c u l a r Specimen: diameter =6.66 mm. Table 8 63 X-ray D i f f r a c t i o n data for Specimens Reacted in Moist Nitrogen (4.6 mm. water) at 45°C. (Cu K>< r a d i a t i o n , Ni f i l t e r ) a . Reddish Brown Product ( Prepared Surface ) Line Intensi ty Measured Corresponding Line i n d spacing Card No. 2-0301 1 100 3.90 A L i 3 N !» 3.90 2 88 3 .16 A 3.18 3 20 2.73 A ft 2.75 4> 20 2.45 A tr 2.49 5 48 2.32 A Aluminum Holder 6 64 2.01 A rt it 7 34 1.94 A L i 3 N it 1.95 8 48 1.82 A 1.83 9 40 1.65 A tt 1.66 10 86 1.42 A Aluminum Holder 11 28 1.33 A L i 3 N tt 1.33 12 90 1.21 A 1,22 13 16 1.16 A tt 1.20 14 18 1.05 A it 1.06 b. Black F i lm Line Intens i ty Measured Corresponding Line i n d spacing ASm Card No. 4-0708 and 1-1131 1 64 4.41 A LiOH 4.34 (001) 2 100 4.19 A P a r a f f i n Wax 3 46 3.96 A P a r a f f i n Wax 4 100 3.75 A P a r a f f i n Wax 5, 70 2.78 A LiOH 2.75 (101) 6 50 2.53 A LiOH 2.51 (110) 7 46 2.49 A L i 2.48 8 72 2.24 A LiOH 2.17 (002) 64. Table 9 Reaction Rates of Li t h i u m Disks i n Dry Nitrogen a f t e r I n i t i a t i n g the Run i n Moist Nitrogen ( ^ h^Q r 4°6 mm.. ) Temp. F r a c t i o n o f the Specimen Tra-nsformed React. Time 35°G 40°G 45°C 45°G 50°G 50°C 0 min, 0 0 0 0 0 0 15 0,5 0.3 0.7 0.9 0.8 0-4 30 2.2 1-3 2.1 3..5 3-5 1,8 45 4.1 3.9 6-5 13 -o# 9-6 4.7 60 6.8 9.6# 18 .1# 25..0 20.8# 11 -4 75 1.3 .0# 19-2 28.6 34-7 30.2. 19-5 90 21.7 27.2 33.9 43 -2 38-4 26.9 105 29«8 34.7 47.6 51.1 47-3 3 5.3 120 36.7 41.3 57.2 53-4 52 „.6 43 0.3 135 42.9 43.4 65.I 65.1 59.3 510.9 150 48. L. 54.8 72 ...5 7/0-9 67-0 59 .-3 165 53 -5 60 06 78..0 75-9 73-5, 67 -6, 180 5 8..4 67.0 33.5 30.6 79^3 74,-2 195 62.3 7 2 0.5 36-9 85 0.2 85-2 79-4 2110 66.3 77.6 90-6 88.6 84-6 225 70-2 82-5 94 ..0 89 -1 240 73 .4 86.6 96-6 92.2 255 76.4 90-0 98-4 96.0 270 79-4 93 o.4 99-6 99-2 285 81.7 960.4 100 100 300 84 0.2 98-5 100 315 86.6 99-4 330 88-9 99.8 390; 960.2 100 495 100 # Moment at which the S h i f t to Dry Gas was Car r i e d o u t . 65'. Table 10 Analys i s of Runs in Dry Nitrogen Which were I n i t i a t e d ' i n Moist Nitrogen ( b Determined from the Data i n Table 9 using the Relat ion - a _ b t ; R _ 6 e 6 6 ranu ) # a. Determination of Growth V e l o c i t i e s . Temp t b V - • k ,SL 3 5°G .000183 .016 mm./min. 40°0 ,00028 „020 45°C . 000 50 5 =027 45°G ,00043 ,02 5 50°G ..00057 -029 b. Determination of A c t i v a t i o n Energy 1 T . T° K V^ _ 3 5-pC .,003246 „016 mm,/min, 40°G o 003194 .020 45 QC .,003144 c027 45°C .003144 =.025 50°G ,003100 =029 A c t i v a t i o n Energy Q r -7,300 c a l s , _APPEN.D,IX„,11 .Tabl.e_l Weight Incfeasffs of Lithium Disks Reacted with Moist Oxygen at Vari-SUs Temperatures ( Water Pressure = 4 .6 mm.. Hg. ; Specimen Area = 2.792 em . ), React. Time Min. 22°C ; 22?_,Q . 25 °C 2,8°,G 3Q°.C. 3_Q°,C 32°C 35°C 3 5°C. 4,Q°,C. OJ 0 0 0 0 15 0 .45 0..2 0 .4 O..65 30 0.9 0.3 0*7 0 . 8 45 1..2 5 0 .55 0.9- 1.-05 60 1.-5 0 . 8 1..1 1.3 75 1.75 1.1 1,3 1.55 90 2 .05 1.3 1..5 1,.8 105 2.3 1.5 1..7 2..05 120 2 .6 1.7 1 . 9 2 .25 13 5 2 . 8 1.9 2.1 2 . 5 150 2 .95 2.2 5 2...6 5 165 3..2 2,1-5 2.,4 5 2..85 180 3.-4 2 .25 3 a . 195 3 .6 2.-45 2-,.85 3.3 5 210 3 .75 2 ,6 3 .0 3.-6 225 3*95" 2 .75 3..2 3 .35 240 2 .9 3 .4 4 .1 255 4.3 3 ..05 3 .55 4.3 5 270 4 .45 3 ..2 3 .75 4 . 6 285 4*65 3 .4 4 .0 4.85 300 4.85 3.55 4.3 5*1 315 5.0 3 .75 4 .55 5*4 330 5.1-5 4 .0 4 .8 5.7 345 5,-3 5.-65 6^0 360 : 5.5 4.4 5.3 6 .3 5 375 5.6 4.65 5.65 6 .7 390 5-8 4.-9 6 .0 7 .1 405 6 .0 5.1-5 6,*3 7 * 5 420 6.2 5.35 6 . 6 7.-9 43 5 6 , 3 5.55 6 .95 8 .3 450 6 .5 5,8: 7*3, 8 ,7 465 6.75 6 .05 7 .65 9.-1 480 6 .9 6.2-5 8 .0 9.-.5 495 7 .0 6..4 5 8.4 9 .9 510 7.15 6.7 8..8 10 ..3 525 7.3 6.95 9.1-5 10 .7 540 7 .5 7 *2 11 .1 555 7 .8 7.45" 9 .9 570 8.0 7 .7 10 s 2 5 585 8.2-: 10 ,.6 600 10,.9 5 645 705 720 10 .4 0) 0*4 0 .9 1.4 2*0 2..5 3 .05 3 .5 3 .9 4,..2 4.55 4 ,9 5.-2 5 . 5 6,1 6..3 6.55 6 , 8 7 ,0 7.35 7.7 7*9 8 a 8.5 9.7 10... 3, 11 .1 11. ..8 12.6 13.4 14.3 0 0,.4 0..7 1,0 2.15 2 . -55 2..9 3.25 3 .6 3 . -95 4 .2 4 . 5 5 4.85 5.2 5-5 5.-9 6,35 6.75 7.2 7.6, 8,05 8.5 8L 9 5 9..4 9.9 10.35 10.9 11.35 I I . 8 5 12,3 12 .8 13 ..25 745 19.-9-19.95 0 0.4 0 . 7 1..0 1.3 5 1..3 2 .15 2;. 5 2.85 3 ..20; 3.55 3 .9 4 . 2 5 4.60 4 .95 5.20 5.6 6 .0 6.3 6 .7 7 .0 7.4 7 .85 8.3 8.7 9 .1 9 . 5 9 .9 10 .4 10..8 11 ..2 5 11.7 12.2 12 .7 13.15 13 ..6 14.1 14.55 15 .0 15 .5 16 .0 16 .5 0 0.3 5 0.80 1..15 1.6 2;.l 2..5 3 . 0 3.45 3.85 4.2 4 .65 0 0,3 0,7 1*1 1.55 2:..0 2*4 3 .4 4.2 4*55 5.5 5.95 6..4 6..9 7-3 5 7.35, 7.7 8.7 9*0 9*7 10,2 11.2 11,8 11.2 12.2 14.2 13.3 14.7 14-4 1 5 . 5 16,.6 18..8 0 Q)*-4 0*7 1,1. 1,7 2,2 3*25 3*8 4.3 5*2 5,.6 6 ..2; 6,75 7.3 7 .35 8^45 9 .05 9.7 10 .4 11,0 11.55 12'.-2 5 12 s 9 13.5 14.2-15.6 4:IJG 9) Q,„3 5 0 = 7 1,2 1*9 . 2*7 3.45 4-2 4-* 81 5.5 6,1| | s 8 7.4 8,0 8,7 10.2 10.9 11.6 12,4 13*15 13*9 1-4.6 15.3 16,0 16,7 17.4 18.15 18,85 24*2 2-5*35 2 5.9 2 8 . 5 Table 1 ( continued ). React. £7^ Time Min. 22° C 765 780 11.4 795 825 8 4 0 12.5 900 13.8 960 15.1 990 15..6 1215 1230 1245 1260 1275 1320 1365 1395 1470 1530 27..4 22.4 17.2 17.6 34.7 27 ..5 2 8 . 5 4 2 . 2 6 8 . 7 5 4 . 6 5 -47.0 32.,1 4 8.I 4 4 . 3 6 8 . Table 2 . Summary of Data for Reaction in Moist ( 4.6 mm. HigO ) Oxygen. Rate Constants. k 2 Temp. k2 k l 22°C ..004l7nig. / cm^  -min. . 007l6mg,/cm^ -mjh. 1.7 22 .00391 .00738 1.9 25 .00461 .00837 1.8 28 .00573 .00955 1 .7 30 .00674 .0118 1.8 30 # .0107- -32 .00836 .0114 1.4 35 .0107 ..0126 1.2 35 .0104 .0131 1.3-40 ..0122 .0158 1.-3 42 # it — # Non-linear Reactions. 69. Table 3 Reaction Rates of Lithium Disks with Moist Helium at Various 2 Temperatures ( PH20 =4.6 mm. Hg.; Specimen Area = 2.792cm ) 525 540 34.25 555 13.4 570 13.7 585 600 615 / . 18.9 645 20.05 795 25.15 .Weight Gain (mg.) React. 28°C Time. 28°C 30°C 32°C 3 5°C 45°c 28°C # 0 0 0 0 0 0 0 0 15 0.2 0.45 .0.75 0.3 0.3 0,.6 0,3 30 0.55 0.6 1.0 1.0 0.65 1.2 1.4 45 0.9 0.8 1.35 1.5 1.15 2.05 2,1 60 1.2 1.1 1.6 2.0 1.7 3.1 2.7 75 1.6 1.4' 1.85 2.45 4.2 3.3 90 2.0 1.7 2.1 2.9 2,8 5.3 105 2.2 2.1 2.4' 3.4 3.4 6.4 4.2 120 2.45 2.7 3.8 4.0 7.6 4.8 13 5 2.8 3.1 4.4 4.45 8,8 5.25 150 3.3 3.4 4.8 4.9 9.9 5.8 165 3.65 3.45 3.7 5.2 5.4 10,85 6,2 180 4.0 4.0 5.6 5.8 11.95 6.6 195 4.6 4.1 4.3 6.0 13.0 7.0 210 4.55 6.5 6.8 14.1 7.4 225~ 4.9 4.85 4.9 6.8 15.1 7.75 • 24a 5.2 5.6 5.2 7.2 7.75 16.15 7.95 255 5.55 5.5 8,1 270 5.85 5.8 7.6 8.6 285 6.25 6.2 7.9 18.95 8,3 300 6.5 6.6/ 8.2 9.45 19.85 8.5 315 6.9 7.0 8,6 20.75 330 7.35 9.0 9.9 345 7 .-6 5 9.3 360 8.8 375 8.35 10.0 11.05 390 10.4 11.45 9.0 405 9.05 10.7 12.0 25.3 420 11.0 12.4 9.1 435 10*3 11.4 12.8 450 11.75 13.2 465 11.0 12.0 13.65 480 12.2 14.1 495 14.6 510 1.5.1 70. Table 3 (continued) Weight Gain (mg.) R.S 6. C t o Time.° 28°C 28°C 30°C 32°C 3 5°C 45°C 28°C # 1170 30.8 1185 31.3 1200 31.8 1260 22.5 1290 23.3 E f f e c t o f Water Pressure on R e a c t i o n Rate Constants i n Wet Argon at 3 5°C ( v/alues taken d i r e c t l y from r e c o r d e r - c h a r t ) 1320 1380 3 6 . 9 # R e a c t i o n Gas a Mixture of 50$ He, 50$ 0 2 . Table 4 Pressure of Water-Vapour (mm. Hg.) 2.6 4.6 8.2 12.6 .00389 .0108 .0100 .0116 .0122 .0147 .0152 .0162 3.1 1.4 1.5 1.4 71. Table 5 X- ray D i f f r a c t i o n Data for Specimens Reacted with Water-Vapour (4.6 mm.) (Cu K Radiation; Ni f i l t e r ) a. Black Film (specimen Reacted with Moist Oxygen 2 hours at 40°C) Gorresp. Line in Calc. d A.S.T.M. Cards No. Line Inten. Spacing 4 - 0 7 0 8 and 1-1131 1 14 4 . 3 9 A LiOH 4 . 3 4 (001) 2 13 4 . 1 5 P a r a f f i n } 11 3 . 9 1 P a r a f f i n 4 8 3 . 7 3 P a r a f f i n 5 14 2 . 7 6 LiOH. 2 . 7 5 (101) 6 100 2 . 5 1 LiOH 2 .51 (HO) 7 13 1-99 Unknown 8 16 1 . 2 4 5 L i 1 .24 b„ White Reaction Product ( Specimen Reacted in Moist Oxygen for 24 hours at 40°C ). Corresp. Line i n Calc. d A . S . T . M o Cards No. l i n e Inten. Spacing 4 - 0 7 0 8 , 1 - 1 1 3 1 , 1 - 1 0 6 2 1 28 4 . 5 7 A Par a f f i n Wax 2: 65 4 . 3 7 LiOH; 4 . 3 4 (001) 3 47 4 . 1 9 P a r a f f i n Wax 4 30 3 . 7 5 P a r a f f i n Wax 5 53 2 . 8 1 Li0H>H 2 0 2..80 6 100 2 . 7 4 LiOffi 2 . 7 5 (100) 7 35 2 . 5 7 LiOK'H'oO 2 . 5 9 8 100 2 . 5 2 LiOH 2 . 5 1 (110) 9 85 2 . 4 9 L i 2 . 4 8 10 22 1 .85 LiOffi 1 . 8 5 (102) 11 55 1 .77 LiOffi 1 . 7 8 (200) 12 23 1 . 6 7 LiOH 1..65 (201) 13 36 1 .64 LiOH 1 .64 (112) 14 21 1 .51 LiOH.H20 1 . 5 0 15 35 1 . 4 9 LiOH 1 .49 (211) 16 17 1 . 4 5 L i 1 .43 17 16 1 . 2 6 LiOH 1 .26 (220) 7 2 . Table 5 ( continued ). C o Black F i lm ( Specimen Heated in Moist Argon 2 hours at 40°C ). Corresp. Line i n C a l c . d A .S . T . M . Cards No. Line i n t e n „ Spacing 4' -0708,and 1-1131. 1 52 4.39 LiOH 4.34 (ool) 2 100 4 . 15 Paraffim Wax 3 32 3.95 P a r a f f i n Wax 4 84 3 . 7 4 Paraf f in Wax 5 24 2.85 Li0Hi»H~20 2.80 6 42: 2.75 LiOH 2.75 (100) 7 72 2.54 LiOH 2.50 (110) 8 100 2.49 L i 2.48 9 16 1.77 LiOH 1.78 (200) 10, 16 1..45 L i 1.43 11 28 1.11 LiOH 1,12 (.004) do White Reaction Product (Specimen Reacted in Moist Argon for 20 hours at 40°C ). Corresp. Line in C a l c . d A .S . T . M . Cards No. Line Inten. Spacing 4-0708,1-1131.1-1062 1 31 4.59 Paraf f in Wax 2 68 4.37 LiOffi 4 . 3 4 (001) 3 100 4.15 Paraf f in Wax 4 72 3.73 Paraf f in Wax 5 47 2o83 LiOH°H 20 6 100 2„76 LiOH 2.75 (101) 7 30 2 .57 Li0H°H ?0 2.59 8 88 2.51 LiOH 2.51 (110) 9 20 2.24 Li0H°H 20 2 .24 10 18 2.18 LiOH 2.17 (002) 11 26 1.86 LiOH 1.85 (102) 12 24 1 .81 Li0H°H 20 1.79 13 86 1.78 LiOH 1.78 (200) 14 24 1 .67 LiOH 1.65 (201) 15 42 1 . 6 5 LiOH 1 .64 (112) 16 21 1 .51 LiOH->H20 1.50 1-7 35 1.49 LiOH 1.49 (211) 18 25 1.43 L i 1 .43 19 21 1.26 LiOH 1.26 (220) 20 13 1.207 LiOHI 1.21 (221) 21 12 1.144 LiOH 1 . 14 (301) 22 13 1.144 LiOH 1 .12 (310) 23 13 1.041 LiOH 1.04 (104) 24 11 0 . 9 9 8 LiOH 0 . 9 9 8 (312) 25 11 0o96l LiOH 0.962 (321) Table 5 (continued). eo X-ray D i f f r a c t i o n Data for a Sample Reacted to Completion in Moist Oxygen ( PH20 - 8.2 mm. Hg. ) at 35°C. Line Inten. C a l c . d Spacing Corresp. Line in A.S Cards No. 1-1062 1 63 2.92 i LiOH°H 20 2.97 21 52 2.79 : tt 2.80 3 44 2.70 ft 2.67 1* 52 2.47 tt 2.44 5 63 2.41 Unknown 6 48 2.25 LiOH°H 20 2.24 7 48 1.86 tf 1 o 85 8 42 1.73 1.75 9, 55 1.66 i t 1.66 10 44 1.58 tt 1.60 11 48 1.51 i t 1.50 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0106079/manifest

Comment

Related Items