Crystal structures, magnetic and thermal properties of Ln3IrO7 (Ln = Pr, Nd, Sm, and Eu)

Ternary iridium oxides Ln(3)IrO(7) (Ln= Pr, Nd, Sm, and Eu) were prepared and their crystal Structures, magnetic and thermal properties were investigated. Powder X-ray diffractions (XRDs) were measured for all samples and neutron diffraction (ND) Measurements were performed for Pr3IrO7. All the profiles were refined with space group Cmem (No. 63). The lattice parameters for Pr3IrO7 refined by using ND data are a = 10.9782(13) Angstrom, b = 7.4389(9) Angstrom, and c = 7.5361(9) Angstrom. From specific heat and differential thermal analysis (DTA) measurements, Ln(3)IrO(7) (Ln= Pr, Nd, Sm, and Eu) show thermal anomalies at 261, 342, 420, and 485 K, respectively. The results of powder high-temperature XRD and ND Measurements indicate that these anomalies are due to the structural phase transition. Magnetic Susceptibilities of these compounds were measured in the temperature range between 1.8 and 400 K. Nd3IrO7 shows an antiferromagnetic transition at 2.6 K. A specific heat anomaly has also been observed at the same temperature. For Ln(3)IrO(7) (Ln= Pr, Sin, and Eu), no magnetic anomalies have been found in the experimental temperature range. (C) 2003 Elsevier Inc. All rights reserved.