Year: 2025
Type: article
Abstract: Multi-order perovskite oxide is derived from ABO3 perovskite oxides. In this kind of ordered structure, three-quarters of the A sites are replaced by transition metal Aʹ cations, and A and Aʹ sites are orderly arranged in a 1:3 ratio, resulting in the formation of the A-site ordered quadruple perovskite oxide AAʹ3B4O12. Furthermore, when half of the B sites are replaced by another different ion Bʹ, meanwhile the B and Bʹ sites are arranged in a rocksalt-type order, the A- and B-site ordered quadruple perovskite oxide AAʹ3B2Bʹ2O12 thus forms. Because of the ability to accommodate versatile magnetic ions in various cation sites, as well as the framework constructed by corner-sharing A′O4 square-planar and B/BʹO6 octahedra units, multi-order perovskite oxides hold abundant magnetic and electric interactions, giving rise to interesting physical properties such as high dielectric constant, zero/negative thermal expansion, charge ordering, high-temperature magnetism, colossal magnetoresistivity, ferroelectricity, magnetoelectric multiferroicity, half-metallicity and electrocatalysis. These features make multi-order perovskite oxides significant for fundamental research and promising for practical applications. Nevertheless, studies on multi-order perovskite oxides are quite limited on account of the size mismatch between the small Aʹ cations and the B cations. A high-pressure technique is usually indispensable to synthesize such compounds. In this review, we first make a brief introduction to the structural characteristics of multi-order perovskite oxides and the high-pressure synthesis technique employed. Then we focus on the recent progress of multi-order perovskite oxides in three different fields of magnetoelectric multiferroic, half-metallicity, and electrocatalysis: (1) the first observation of magnetoelectric multiferroicity in a cubic perovskite LaMn3Cr4O12. The magnetic structure breaks the spatial inversion symmetry, thus giving rise to spin-induced ferroelectricity. Especially, when the A site is replaced by Bi3+ with 6s2 lone pair electrons, both strong magnetoelectric coupling and large electrical polarization are realized in BiMn3Cr4O12. Furthermore, in TbMn3Cr4O12, the nontrivial topologic Roman surface was experimentally observed for the first time. In another case, in CaFe3Ti4O12, the displacement of the magnetic Fe2+ ion gives rise to the ferroelectricity. The antiferromagnetic ground state of Fe2+ can be readily tuned by external magnetic fields toward ferromagnetic corrections. As a result, large magnetoelectric coupling effects are realized in this displacement-type ferroelectric. (2) The realization of ferrimagnetic half-metallicity in LaCu3Fe2Re2O12 with a high Curie temperature up to 710 K accompanied with a wide majority-spin gap of 2.3 eV and a large saturated magnetization of 8 μB f.u.−1. Half-metallicity was also observed in the osmium-based multi-order perovskite oxides NaCu3Fe2Os2O12, and the Fermi surface can be well-tuned by changing the A site cation. (3) Enhanced activity of oxygen evolution reaction (OER) in CaCu3Ir4O12 owing to the strong 3d-2p-5d orbital hybridizations via the corner-shared Cu-O-Ir framework. The special orbital symmetry as well as the delicate 3d-5d levels enhance orbital overlap, thereby promoting charge transfer. The OER procedure of CaCu3Co2Ru2O12 was traced by in-situ X-ray absorption spectroscopy, and the lattice-oxygen oxidation mechanism is responsible for its high OER activity. Finally, we make perspectives on multi-order perovskite oxides and their potential applications in future technologies, such as logic elements, spintronics devices, and electrocatalysis.
DOI: 10.1360/tb-2025-0008
Authors: Xiao Wang, Xubin Ye, Zhehong Liu, Youwen Long
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W4408897347