Crystal structure of GdFeO3-type rare earth gallates and aluminates

The crystal structures of the lanthanum and neodymium gallates and yttrium aluminates, doped with neodymium and erbium were investigated by means of X -ray structure analysis (full profile Rietveld refinement, powder diffracto meters HZG-4 and DRON-4, Cu and Co K-alpha-radiation). A comparative crysta llochemical analysis of the studied structures was performed. All examined compounds belong to the orthorhombically distorted GdFeO3-type of structure , space group Pbnm, Z=4. It is shown that the structure deformation paramet ers such as the rare earth cation shift, the bond length distortion of the polyhedra, and the tilt angles of octahedra increase in the sequence: LaGaO 3-NdGaO3-YAlO3:Nd-Y0.5Er0.5AlO3. (C) 1999 Elsevier Science S.A. All rights reserved.