Chloride-fluoride-graphite ternary compounds: Preparation and characterization

Abstract

Stage 1 ternary MCl n-M′F n′-graphite bi-intercalation compounds ( M = Fe, Co, or Cu and M′ = B or Nb) have been prepared by the reaction of a fluoride vapor (BF 3 or NbF 5), under fluorine gas, with stage 2 metal chloride-graphite intercalation compounds (FeCl 3, CoCl 2, or CuCl 2-GIC). The reaction products were characterized by X-ray diffraction, FT-IR spectroscopy, and 19F NMR measurements. The measured repeat distances, I c , fit well with the sums of the respective repeat distances d 1 ( MX n - G), which would be exhibited by the stage 1 metal halogenide-GIC ( I c = d 1 (MC1 n-G) + d 1(M′F n′-G)). Unusual NMR line-shifts have been observed with compounds containing magnetic species such as Fe and Co. On the basis of these results, a three-step mechanism for the intercalation of a second reagent, M′ X′ n′ , into stage 2 MX n - GIC binary compounds is proposed. At first, a ternary bi-intercalation phase is formed, then a cointercalation phase can be obtained to finally give binary M′ X′ n′ -GIC in the third step. This would permit the obtention of original binary compounds which do not form by the more conventional procedures.