Enhancing the Neel temperature in 3d/5d R2NiIrO6 (R=La, Pr and Nd) double perovskites by reducing the R3+ ionic radii

Double perovskites containing Ir4+ were synthesised by a citrate technique, followed by an annealing treatment in air at 1100 degrees C. The crystal structure of the three compounds, with formula R2NiIrO6 (R= La, Pr and Nd), were determined using a combined refinement against neutron powder diffraction (NPD) and synchrotron x-ray powder diffraction (SXRPD) data sets. At room temperature, all the samples were indexed in the space group P2(1)/n and the monoclinic symmetry remains in the 300 to 1273 K temperature range. Magnetization measurements suggest competitive antiferromagnetic and ferromagnetic interactions, with an unexpected increment of the ordering temperature (T-N) along the series. The magnetic structures of all the samples were defined with the propagation vector k = 0; the Ni2+ and Ir4+ moment arrangement, different for each compound, shows a strong dependence on the nature of the rare-earth ion. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Double perovskites containing Ir4+ were synthesized using a citrate technique and characterized by NPD and SXRPD, showing competitive antiferromagnetic and ferromagnetic interactions. The magnetic structures of the compounds were found to have a strong dependence on the rare-earth ions, affecting the arrangement of Ni2+ and Ir4+ moments.