There are three distinct classes of perovskite structured metal oxides, defined by the charge states of the cations: AIBVO3,AIIBIVO3, and AIIIBIIIO3. We investigated the stability of cubic quaternary solid solutions ABO3-A′B′O3 using a model of point-charge lattices. The mixing enthalpies were calculated and compared for the three possible types of combinations of the compounds, both for the random alloys and the ground-state-ordered configurations. The mixing enthalpy of the (I,V)O3-(III,III)O3 alloy is always larger than the other alloys. We found that, different from homovalent alloys, for these heterovalent alloys a lattice constant mismatch between the constituent compounds could contribute to stabilize the alloy. At low temperatures, the alloys present a tendency to spontaneous ordering, forming superlattices consisting of alternated layers of ABO3 and A′B′O3 along the  direction.
Bibliographical noteFunding Information:
This work was supported by the British Research Council EPSRC (Grants No. EP/M009580/1 and No. EP/K016288/1) and by the Brazilian Research Agency CNPq. C.C. thanks CNPq (Grant No. 249280/2013-2 PDE). A.W. acknowledges support from the European Research Council (Grant No. 277757).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics