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UBC Theses and Dissertations

The intercalation of bromine- and iodine fluorosulfate derivatives in solutions of fluorosulfuric acid Cader, Mohamed Shah Roshan


The oxidative intercalation of halogen fluorosulfate derivatives such as I(SO₃F) ₃, Br(SO₃F)₃, BrSO₃F, K[I(SO₃F)₄] and K[Br(SO₃F)₄] from solutions in fluorosulfuric acid into graphite (SP-1 and to a lesser extent HOPG) is studied. In addition, the intercalation of solvated cations of the type I₂₊ and NO⁺ is included in this research as well. The results, supported by microanalysis, X-ray powder diffraction data, Raman frequency shifts, Solid state -¹⁹F-NMR spectroscopy and UV-visible optical spectra of the supernatant solutions support three different courses of the intercalation reactions: a) At very high intercalant concentrations (about a five fold excess over the stoichiometrically required quantity) Hal (SO₃F)₃ and the anion [Hal(SO₃F)₄], with Hal - I or Br, intercalate without noticeable solvent cointercalation. b) At intermediate concentrations, solvent intercalation is observed. c) When low intercalant concentrations are used, the only intercalate is found to be the solvent HSO₃F. In all the intercalation reactions except the NO⁺ (solv) promoted synthesis, first stage compounds are formed. These stage one GIC's with c-axis layer repeat distance I[sub c] - 8.0 A are found for the intercalants I₂₊(solv), I(SO₃F)₃, BrSO₃F and Br(SO₃F)₃ with compositions C₃₂SO₃F.₃HSO₃F.0-2I, C₂₂l(SO₃F)₃, C₁₁HSO₃F.0•5SO₃F.xBrSO₃F (x ≤ 0.025) and C[sub 26.8] Br.4SO₃F respectively. K[Hal(SO₃F)₄] (Hal - Br, I) in HSO₃F gave first stage products with formulae C₈₄Br.11•22SO₃F and C₈₆I.10-51SO₃F. The NO⁺ (solv) induced reaction leads to a stage two compound with I[sub c] - 10.6 A, and a general composition of C[sub n] x SO₃F-yHSO₃F is proposed for the product which is compositionally inhomogeneous. In addition, the basal plane electrical conductivity enhancements are measured for the graphite-I₂₊(solv) and graphite-I(SO₃F)₃systems employing a contactless radio frequency induction method.

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