Updated: Sep 30, 2021
Ordering of cations in different structural types occurs when there is a significant difference in the oxidation states and ionic radii of the ions involved. Herein we report an unusual ordering of isovalent cations Fe3+ and Al3+ in the polar rhombohedral R3 double perovskite structure of Bi2FeAlO6 synthesized at high-pressure (6 GPa) and high-temperature (10008C). This ordered structure is derived from the 1:1 combination of the polar oxides BiFeO3 (R3c) and BiAlO3 (R3c), which results in reduction of symmetry to an R3 structure where the Fe3+ and Al3+ ions are ordered in a rock salt manner. However, these ions remain disordered in BiFe1@xAlxO3 (x = 0.2, 0.3, 0.4) perovskites with R3c structure. The ordered compound undergoes antiferromagnetic ordering at TN & 280 K. The butterfly nature of piezoelectric displacement loop further confirms the polar nature of the cationordered Bi2FeAlO6.
Title: Isovalent Cation Ordering in the Polar Rhombohedral Perovskite Bi2FeAlO6
Journal: Angew. Chem. 2018, 130, 16331 –16335