High Solubility of Hetero-Valence Ion (Cu2+) for Reducing Phase Transition and Thermal Expansion of ZrV1.6P0.4O7
YUAN Bao-He1,2, YUAN Huan-Li1, SONG Wen-Bo1, LIU Xian-Sheng1, CHENG Yong-Guang1, CHAO Ming-Ju1, LIANG Er-Jun1**
1School of Physical Science & Engineering and Key Laboratory of Materials Physics (Ministry of Education), Zhengzhou University, Zhengzhou 450052 2North China University of Water Resources and Electric Power, Zhengzhou 450011
Abstract:Large thermal expansion at room temperature and high phase transition temperature of ZrV2O7 limit its practical applications and are reduced by the high solubility of hetero-valence ion (Cu2+) on the basis of an equal-valence substitution of P5+ for V5+. The temperature-dependent Raman spectra show that Zr0.9Cu0.1V1.6P0.4O6.9 maintains a normal parent cubic structure till 173 K and transforms to a 3×3×3 cubic superstructure below 173 K. Temperature dependent x-ray diffraction patterns of Zr0.9Cu0.1V1.6P0.4O6.9 show near zero and negative thermal expansion. High solubility of lower valence Cu2+ relates to an equal-valence substitution of smaller P5+ for V5+, which extends the bond angle of V(P)–O–V in ZrV1.6P0.4O7 close to 180°. The change of microstructure is considered to be responsible for reduced phase transition temperature and thermal expansion.