High-Pressure Synthesis of a B-site Co²⁺/Mn⁴⁺ Disordered Quadruple Perovskite LaMn₃Co₂Mn₂O₁₂

Abstract

A new oxide, LaMn3Co2Mn2O12, was synthesized under high-pressure (7 GPa) and high-temperature (1423 K) conditions. The compound crystallizes in an AA′3B4O12-type quadruple perovskite structure with space group Im3̅. The Rietveld structural analysis combined with soft X-ray absorption spectroscopy reveals the charge combination to be LaMn3+ 3Co2+ 2Mn4+ 2O12, where the La3+ and Mn3+ are 1:3 ordered respectively at the A and A′ sites, whereas the Co2+ and Mn4+ are disorderly distributed at the B site. This is in sharp contrast to R2Co2+Mn4+O6 (R = La and rare earth) double perovskites, in which the Co2+ and Mn4+ charge states are always orderly distributed with a rocksalt-type fashion, giving rise to a long-range magnetic ordering. As a result, LaMn3Co2Mn2O12 displays spin glassy magnetic properties due to the random Co2+ and Mn4+ distribution, as demonstrated by dc and ac magnetic susceptibility as well as specific heat measurements. Possible factors that affect the B-site degree of order in perovskite structures are discussed.

High-Pressure Synthesis and Magnetism of the 4H-BaMnO3 Single Crystal and Its 6H-Type Polymorph

“…Such a reduction may be attributed to the possible covalent effects caused by the pressure-enhanced p–d hybridizations duo to the much higher synthesis pressure of the 6 H phase (20 GPa) relative to that of the 4 H phase (5 GPa). As is well known, XAS is highly sensitive to the valence states − and local environments − for 3d transition metals. This technique was used to further determine the valence state of Mn in BaMnO 3 .…”

Strategic Design and Insights into Lanthanum and Strontium Perovskite Oxides for Oxygen Reduction and Oxygen Evolution Reactions

“…Both A-and B sites contribute to ferroelectricity, and there's an enhancement in A'−B−B' spin interactions, leading to notably high spin ordering temperatures. [62][63][64][65] H. S. Kushwaha et al [66] found one example of a quadruple perovskite in practical use. In their research quadruple perovskite (CaCu 3 Ti 4 O 12 ) was utilized as a bifunctional composite for ORR and OER.…”

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

“…29 This is different from the LaMn 3 M 2 Mn 2 O 12 (M = Co and Ru) system with a disorder of B-site cations and spins which displays a spin glassy magnetic state. 30,31 The control of the A′-B site spin interaction and the ordering/disordering of B-site cations and spins in PbMn 7 O 12 is an intriguing subject to investigate the physical properties of the quadruple perovskite manganite. In this paper, we apply a high-pressure synthesis technique to substitute one-quarter of B-site Mn 3+ in PbMn 3+ 3 (Mn 3+ 3 Mn 4+ )O 12 and prepare PbMn 3 (CrMn 3 )O 12 .…”

“…29 This is different from the LaMn 3 M 2 Mn 2 O 12 (M = Co and Ru) system with a disorder of B-site cations and spins which displays a spin glassy magnetic state. 30,31…”