Structural evolution and physical properties of Bi_1-xGd_xFeO₃ ceramics

The crystal structure and physical properties of Bi_1-xGd_xFeO₃ ceramics with x ≤ 0.5 have been studied by X-ray diffraction, differential scanning calorimetry, dielectric and magnetic measurements. Bi_1-xGd_xFeO₃ compounds crystallize at room temperature in R3c structure for x < 0.08 and in Pbnm structure for x ≥ 0.3. The R3c phase transforms to the Pbnm phase as temperature increases. Temperature-dependent dielectric response and low-temperature X-ray diffraction indicate a phase transition of the Pbnm phase at low-temperature. Detailed structural analysis indicates that the interaction between Bi and O plays an important role in the evolution of structure and physical properties. A phase diagram is constructed to illustrate the physical property-composition-temperature relations.