Synthesis and properties of a new quadruple perovskite: A-site ordered PbMn3Mn4O12

PbMn3Mn4O12 a quadruple perovskite was prepared by high pressure and high temperature synthesis. Powder X-ray diffraction (PXD) and differential scanning calorimetry reveal a structural phase transition at similar to 380 K. Rietveld refinement of the.synchrotron room temperature data indicate rhombohedral symmetry (R-3) with a=6.43675(4) angstrom and alpha=109.556(2)degrees. Similar 423 K PXD data refined in a body centered cubic cell (lm-3) with a=7.4283(9) angstrom. The temperature variation of magnetization, shows a magnetic field dependent antiferromagnetic-like transition at 68 K, and dynamic fluctuations indicative of magnetic frustration. The semiconducting electrical behavior indicates a large decrease in the conductivity near 68 K. The temperature dependence of the real part of the dielectric constant, epsilon(real) increases dramatically at similar to 68 K, and shows relaxor-type ferroelectric behavior as a function of frequency. The intimate coupling of magnetic, electrical and dielectric properties at 68 K in PbMn3Mn4O12 suggests possible multiferroic behavior. (C) 2012 Elsevier Inc. All rights reserved.