Вид документа : Статья из журнала Шифр издания : 54/T 44 Автор(ы) : Rotermel' M. V., Krasnenko T. I., Petrova S. A., Zakharov R. G. Заглавие : Thermally Activated Transformations in Stable and Metastable Copper(II) Pyrovanadate Polymorphs Место публикации : Russian Journal of Inorganic Chemistry. - 2009. - Vol. 54, № 1. - С. 22-26: il. Примечания : Bibliogr. : p. 26 (13 ref.) ISSN: 0036-0236 ББК : 54 Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ Ключевые слова (''Своб.индексиров.''): медь двухвалентная--пированадат меди Аннотация: The structural transformations of α- and β'-Cu2V2O7 phases over the entire temperature range of their existence and α-- β'-Cu2V2O7 and β'-- β-Cu2V2O7 polymorphic transitions in α-Cu2V2O7 are described from the crystal-chemical standpoint. Variations in the parameters of the polyhedral blocks of the α-Cu2V2O7 structure implies that the greatest deformations occur with a negative and near-zero bulk thermal expansion in the range from room temperature to 400°C. The compression and rotation of vanadium–oxygen diortho groups is accompanied by unbending of zigzag copper–oxygen chains, with the distances between them unchanged, which is the reason for the anomalous volume expansion of the structure. Thermal distortion of β'-Cu2V2O7 is insignificant. The thermal expansion coefficients (TECs) of unit cell parameters are as follows: αa = −1.36 × 10–5 1/K, αb = 1.95 × 10–5 1/K, αc = 1.37 × 10–5 1/K, αβ = –0.18 × 10–5 1/K, and αV = 1.93 × 10–5 1/K. We demonstrate that the low-temperature Cu2V2O7 phase can be formed without admixtures of metastable β-Cu2V2O7 upon slow cooling (at about 1 K/min) of the high-temperature phase Доп.точки доступа: Rotermel', M. V.; Krasnenko, T. I.; Красненко Татьяна Илларионовна; Petrova, S. A.; Zakharov, R. G.