Three Perovskite Phases with Different Cation Orders in Sm₂MnMn(Mn_4−xSb_x)O₁₂

Abstract

Cation order, which can be controlled by synthesis conditions and stoichiometry, plays an important role in properties of perovskite materials. Here we show that aliovalent doping by Sb5+ in Sm2MnMn(Mn4−xSbx)O12 quadruple perovskite solid solutions can control cation orders in both A and B sites. Samples with 0.4 ≤ x ≤ 2 were synthesized by a high‐pressure, high‐temperature method at 6 GPa and 1770 K. Three regions with different cation orders were found at 0.5 ≤ x ≤ 1.0, x = 1.5–1.6, and x = 1.8. The 0.5 ≤ x ≤ 1.0 compositions have a B‐site‐disordered and A‐site columnar‐ordered structure with space group P42/nmc; the x = 1.5 and 1.6 samples have a B‐site rock‐salt‐ordered and A‐site columnar‐ordered structure with space group P42/n; the x = 1.8 sample has a B‐site rock‐salt‐ordered and A‐site‐disordered structure with space group P21/n. All the samples show one ferrimagnetic transition: TC increases from 35 K to 73 K for 0.5 ≤ x ≤ 1.0, TC = 81 K for x = 1.5 and 1.6, and TC = 53 K for x = 1.8.