Synthesis method dependence of the lattice effects in Ln0.5M0.5FeO3 perovskites (Ln = La and (Nd or Gd); M = Ba and (Ca or Sr))

Abstract

A new series of cubic iron perovskites with the composition Ln0.5M0.5FeO3 (Ln = La and Nd (or Gd); M = Ba and Sr (or Ca)) with the same average A-site radius (〈rA〉 = 1.3 Å) but different A-site size disorder, σ2(rA), from 0.0114 to 0.0230 Å2, has been prepared by three different synthesis routes: (a) ceramic method, (b) combustion method and (c) the Pechini method. A strong correlation of the structural parameters with σ2(rA) and the synthesis method is observed. The unit cell volume increases with σ2(rA) in all the cases but the overall isotropic displacement factor of the atoms and the lattice microstrain do not show the same trends. Samples synthesised by the low temperature routes show a σ2(rA)-dependence of the microstrain whereas in the oxides prepared by the ceramic method microstrain seems to be σ2(rA)-independent.