Optimized negative thermal expansion induced by gradual intermetallic charge transfer in Bi₁₋ <i> _x </i>Sb<i> _x </i>NiO₃

Abstract

Negative thermal expansion (NTE) induced by intermetallic charge transfer between Bi5+ and Ni2+ was observed in Bi1−xSbxNiO3 (x = 0.05 and 0.10). Bi3+ and Bi5+ had a long-range ordering in the low-temperature phase of Bi0.95Sb0.05NiO3 while the ordering was short-range in Bi0.9Sb0.1NiO3. The latter compound exhibited a continuous NTE with a linear coefficient of thermal expansion (CTE) of αL = −106 ppm K−1 without temperature hysteresis in a wide temperature range of 200–320 K.