Rhombohedral–Tetragonal Phase Boundary with High Curie Temperature in (1-x)BiCoO3–xBiFeO3 Solid Solution

Abstract

The crystal structure change of the solid solution BiCo_1-xFe_xO₃ was investigated in order to determine the phase boundary between tetragonal BiCoO₃ and rhombohedral BiFeO₃. It was found that BiCo_1-xFe_xO₃ with x = 0 to 0.6 had tetragonal BiCoO₃ structures, while those with x = 0.8 to 1 had rhombohedral BiFeO₃ structures at room temperature. The monoclinic √2a ×√2a ×a phase was found for the x = 0.7 sample. The tetragonal-to-cubic phase transition was first observed at around 700–850 °C in Bi-based perovskite for the x = 0.8 sample.