The crystal structure of NdGaO3 at 100 K and 293 K based on synchrotron data

The crystal structure of NdGaO3 is studied at 100 K and 793 K using synchro tron single crystal data. The NdGaO3 structure belongs at low and at room-t emperatures to the orthorhombically distorted perovskite-type (space group Pbnm, Z=4). The analysis reveals that both structures differ considerably i n the character of the thermal motions of the cations. The Nd and Ga therma l ellipsoids at 100 K are reorientated compared with those at 293 K. The an harmonic thermal motions of Nd and Ga, determined for 100 K and 293 Ei are displayed by 4-rank polar tensors. The thermal anomaly of the physical prop erties of NdGaO3 seems therefore, to be well reflected by the thermal behav iour of the cations. (C) 2000 Published by Elsevier Science S.A. All rights reserved.