文摘
A metastable perovskite phase of Bi(Mg1/2Ti1/2)O3 composition (BMT) has been obtained under high-pressure (6 GPa) and high-temperature (1270 K) conditions. X-ray and electron diffraction studies haverevealed a complex superstructure originating from antiferroelectric-like displacements of Bi3+ cationsand octahedral tilting. A group theoretical analysis was used to enumerate the possible crystal structurescompatible with both types of the distortions. On the basis of the symmetry arguments in combinationwith the diffraction methods, it has been concluded that the perovskite BMT is characterized by theorthorhombic Pnnm space group with unit cell parameters a = 11.3207(10) Å, b = 5.6433(10) Å, andc = 7.8314(10) Å. A relation of the BMT crystal structure to that commonly accepted for antiferroelectricperovskite PbZrO3 (PZ) is discussed.