Calculation and discussion of the distribution of double magnetic ions in the lattice site: The perovskite structure with d3 -d5 superexchange interaction

In this paper, for the d3-d5 superexchange perovskite system, the distribution of double magnetic ions in the B-site is quantitatively calculated using molecular field theory. The model we established, which applies to RFe1−pCrpO3, goes one step further than the former anti-site defect one. Calculations have revealed that the distribution of Fe and Cr ions in many previous studies of Fe–Cr perovskite does not always conform to the uniform distribution. Instead, they exhibit an effect that aviods the Fe–Fe or Cr–Cr clustering. This work settles previous disputes regarding the phase transition temperature range of double perovskites and explains why the phase transition temperature shifts with the same given doping proportion. It furnishes theoretical guidance for the design of functional materials with arbitrary phase transition temperatures.