Structural Ordering and Antisite Defect Formation in Double Perovskites

TL;DR

This paper develops an effective lattice-gas model to understand B-B' site ordering and antisite defect formation in double perovskites, explaining experimental phenomena like nonmonotonic order dependence on annealing and effects of overdoping.

Contribution

It introduces a simple yet effective model for predicting ordering behavior and defect formation in double perovskites, applicable to various alloy systems.

Findings

Nonmonotonic order dependence on annealing temperature

Rapid decrease of order with overdoping

Model generalizable to other binary and ternary alloys

Abstract

We formulate an effective model for B-B' site ordering in double perovskite materials A_2BB'O_6. Even within the simple framework of lattice-gas type models, we are able to address several experimentally observed issues including nonmonotonic dependence of the degree of order on annealing temperature, and the rapid decrease of order upon overdoping with either B or B' species. We also study ordering in the `ternary' compounds A_2BB'_{1-y}B''_yO_6 Although our emphasis is on the double perovskites, our results are easily generalizable to a wide variety of binary and ternary alloys.