V 86 Volkov, V. L. Thermal expansion and electrical conductivity of M4±xV6O16±x (M = K, Rb, Cs) polyvanadates [Text] / V. L. Volkov, N. V. Podval'naya // Inorganic Materials. - 2008. - Vol. 44, № 2. - P176-180. - Библиогр.: с. 179-180 (11 назв.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): ТЕРМИЧЕСКОЕ РАСШИРЕНИЕ -- ПОЛИВАНАДАТЫ -- ЭЛЕКТРОПРОВОДНОСТЬ -- СТЕХИОМЕТРИЯ Аннотация: The thermal expansion coefficient of the M4±xV6O16±x(M = K, Rb, Cs) polyvanadates is a nonmonotonic function of temperature, with sharp minima at 663, 558, and 713 K, respectively, which are accompanied by no changes in cell symmetry (tetragonal) or a /c axial ratio. The polyvanadates are shown to be ionic–electronic conductors. The activation energy for electronic conduction in the three polyvanadates is 0.43±0.02eV. In the range 675–740 K, the conductivity of K4.2V6O16.2 shows metallic behavior. Rubidium polyvanadate has a narrower temperature range of unactivated conduction, and Cs3.8V6O15.8 has no such range. The conclusion is made that these phases undergo cation disordering due to deviations from the M4V6O16 stoichiometry Полный текст |