Material Design and High-Pressure Synthesis of Novel <i>A</i>-Site-Ordered Perovskites <i>A</i>Mn3Al4O12 (<i>A</i> = Y, Yb, and Dy) with Square-Planar-Coordinated Mn3+

Abstract

Abstract Structural stability of A-site-ordered perovskites AMn3Al4O12 was evaluated by the global instability index calculated from the SPuDS program. Based on the results, we “designed” new compounds AMn3Al4O12 (A = Y, Yb, and Dy), and these compounds were synthesized with a high-pressure technique. The obtained compounds were ionic crystals, A3+Mn3+3Al3+4O2−12, with fourfold square-planar coordination for Mn3+ at the originally twelvefold-coordinated A site of the ABO3 simple perovskite structure. Structural parameters obtained from the structure refinement well agreed with the “predicted” values. The synthesized compounds contained magnetic Mn3+ ions with S = 2 spins at the A′ site, and the A′–A′ interaction resulted in antiferromagnetic ordering of the Mn3+ spins at temperatures ranging from 29 to 40 K. The Yb3+/Dy3+ moments in (Yb/Dy)Mn3Al4O12 were found to be paramagnetic even below the antiferromagnetic transition temperatures.