High-pressure synthesis of A-site ordered perovskite PbMn3(CrMn3)O12 with long-range antiferromagnetic ordering and a spin glass transition

Abstract

An AA′₃B₄O₁₂-type perovskite oxide PbMn₃(CrMn₃)O₁₂ was synthesized by high-pressure solid-state reactions at 8 GPa and 1373 K. Synchrotron X-ray diffraction shows a cubic crystal structure with the space group Im. The charge states are verified by X-ray photoelectron spectroscopy to be PbMn³⁺₃(Cr³⁺Mn³⁺₂Mn⁴⁺)O₁₂, where the Pb²⁺ and Mn³⁺ are 1 : 3 ordered respectively at A and A′ sites, while the Cr³⁺, Mn³⁺ and Mn⁴⁺ are disorderly distributed at the B site. PbMn₃(CrMn₃)O₁₂ features a long-range antiferromagnetic order of A′-site Mn³⁺ spins at about 66 K and a subsequent spin glass transition around 36 K due to the randomly distributed Cr³⁺, Mn³⁺, and Mn⁴⁺ cations at the B site. This unique stepwise order of A′ and B-site spins indicates weak A′–B site spin interactions, which are dominated by the difference in the B-site Mn³⁺/Ni²⁺ and Mn⁴⁺ number in the quadruple perovskites AMn₃B₄O₁₂.