Structural ordering and antisite defect formation in double perovskites

摘要

We formulate an effective model for B-B' site ordering in double perovskite materials A(2)BB'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(2)BB'(1-)yB '' O-y(6). Although our emphasis is on the double perovskites, our results are easily generalizable to a wide variety of binary and ternary alloys.