層状構造をもつ水和バナジウム酸化物の合成と相転移

概要

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Hydrated vanadium oxides were prepared by hydrothermal treatment of aqueous VOSO_4 solutions. The products were found to take layered structures based on the V_2O_5 structure. Phases with the layer spacings of 701, 803, 13.2, 14.2 and 19.0 A^^° were obtained and a primary product was the phase with the spacing of 14.2 A^^° (phase I). The composition of the phase I was estimated as V_2O_<5-δ>・nH_2O (0<δ<0.2, 1.5< n<2.5). An additional phase with the spacing of 17.3 A^^° (phase I') was found in as-filtrated samples, which changed to the phase I by drying. The phase I transformed successively into the phases with smaller layer spacings by dehydration on heating or evacuating. The overall transitions were as follows ; I' (17.3 A^^°)→I (14.2 A^^°)→Ia' (12.6 A^^°)→Ia (11.5 A^^゜)→Iβ (10.0 A^^°)→Iγ(8.3 A^^゜). The transition from phasel to Iβ was reversible. These layer- type phases were distinguished from V_2O_5 gels.
社団法人日本セラミックス協会の論文
1989-12-01