Crystal structure of NdNiO3 at 123 and 292 K

Abstract

Well-shaped, small single crystals of the NdNiO3 perovskite were grown under high oxygen pressure conditions in a belt-type press at 4 GPa. The reaction took place in sealed platinum capsules in the presence of KClO 3 as oxidizing agent. It seems that the choice of hydroxides of the involved cations as precursor reagents is crucial for the success of the crystal growth, via water vapor transport reactions. NdNiO3 was investigated by X-ray powder and single crystal diffraction at 123 and 292 K: GdFeO 3 type, Pbnm, a = 538.10(7), b = 537.91(7), c = 760.26(10) pm, wR2 = 0.0434, 338 F2 values, and 29 variables at 292 K. The low-temperature data gave no hint for a monoclinic distortion: Pbnm, a = 537.91(8), b = 538.49(8), c = 760.02(12) pm, wR2 = 0.0299, 338 F2 values, and 29 variables. At room temperature, the Ni-O distances vary from 193.9 to 194.2 pm, and the O-Ni-O angles cover the range from 89.5 to 90.5°. Similar small distortions are observed for the NiO6 octahedra at 123 K. Due to the strong orthorhombic distortion, the neodymium atoms have only nine oxygen neighbors at Nd-O distances from 236.0 to 295.7 pm. © 2006 Verlag der Zeitschrift für Naturforschung.