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

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 Im3¯. 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. [ABSTRACT FROM AUTHOR]