Anisotropic Thermal Expansion and a Second-Order Charge Order Transition in the Ferrimagnetic DyCuZnMnO Perovskite with Triple A-Site Cation Ordering.

DyCuZnMnO perovskite, belonging to the A-site columnar-ordered quadruple perovskite family with the general composition of AA'A″BO, was prepared by a high-pressure, high-temperature method at 6 GPa and 1500 K. Its crystal structure was studied by synchrotron powder X-ray diffraction between 100 and 800 K. The ideal cation distribution (without antisite disorder) was found to be realized within the sensitivity of the synchrotron X-ray diffraction method. Between 100 and 400 K, it crystallizes in space group (no. 59) and has layered charge ordering of Mn and Mn at the B sites. Above 425 K, it crystallizes in space group 4/ (no. 137) with one crystallographic B site and an average Mn oxidation state. The charge ordering transition (at = 425 K) appears to be of the second order as no anomalies were found on differential scanning calorimetry curves and temperature dependence of the unit cell volume, and the orthorhombic and lattice parameters merge gradually. The compound demonstrates anisotropic thermal expansion with the lattice parameter decreasing with increasing temperature above 280 K. A ferrimagnetic transition occurs at = 116 K with an additional, gradual rise of magnetic susceptibilities below 45 K, probably due to increases of the ordered moments of the Dy sublattices.