Anion order in perovskites: a group-theoretical analysis

Area of Science:

• Solid State Chemistry
• Crystallography
• Materials Science

Background:

• Perovskite structures are crucial in materials science, with anion ordering significantly influencing their properties.
• Understanding anion ordering in perovskites is key to designing new materials with tailored functionalities.

Purpose of the Study:

• To systematically investigate anion ordering in cubic perovskite structures using group-theoretical methods.
• To classify and predict potential low-symmetry structures arising from anion ordering.

Main Methods:

• Group-theoretical analysis applied to cubic perovskite structures.
• Identification and classification of aristotype structures and their derivatives.
• Theoretical calculation and reporting of specific anion superstructure models.

Main Results:

• Established the possibility of 261 unique ordered low-symmetry perovskite structures.
• Identified five binary and 14 ternary anion superstructures.
• Proposed a classification system (AX, BX, X classes) for perovskite anion order, highlighting the prevalence of AX and BX classes due to coupled cation ordering.

Conclusions:

• The theoretical framework predicts a vast array of anion-ordered perovskite structures.
• The proposed classification provides a systematic approach to understanding perovskite structural diversity.
• Theoretical predictions show strong coherence with experimentally observed anion superstructures, validating the group-theoretical approach.