Ambient pressure synthesis and structure and magnetic properties of a new A- and B-site ordered multinary quadruple perovskite

Abstract

Quadruple perovskites with high magnetic transition temperatures are an interesting class of compounds but are synthesized typically under high pressure. Ambient pressure synthesis of new multinary quadruple perovskites having a high global instability index (GII) and transition temperature can be interesting for future exploration of high-T_C oxides. A new A- and B-site ordered multinary quadruple perovskite, LaCu₃Fe₂RuSbO₁₂, is synthesized by conventional solid-state reactions at ambient pressure. Rietveld structure refinement revealed that the compound crystallizes in the Pn space group with a lattice parameter of 7.4556(4) Å. The compound showed complete 1 : 3 ordering of La and Cu at the A-site and 1 : 1 rock-salt ordering of Fe with Ru/Sb at the B-site. The compound is also probed with scanning and transmission electron microscopy and XPS to investigate the chemical composition, microstructure, lattice and oxidation states of the elements. Magnetic studies revealed antiferromagnetic (AFM) correlations with magnetic ordering transitions at ∼170 and 40 K. Furthermore, the M–H hysteretic behavior at 100 and 5 K indicated ferrimagnetism due to short-range AFM interactions among Fe³⁺(3d⁵) and Ru⁴⁺(4d⁴) spins involving Cu²⁺(↑)–Fe³⁺(↓)–Ru⁴⁺(↑) triads. The specific heat data reaffirmed the magnetic signatures while electrical transport showed semiconducting behavior with variable range hopping. The details of synthesis and structural and compositional studies along with the magnetic and electrical transport properties of LaCu₃Fe₂RuSbO₁₂ are reported in this paper.