SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF CATIO3 DOPED WITH 0.05-7.5 MOLE-PERCENT GADOLINIUM(III)

Titanates containing 0. 05-7. 5 mole% gadolinium(III) in the CaTiO//3 perovskite lattice have been prepared and characterized by X-ray diffraction and absorption, electron paramagnetic resonance, and Raman methods. The structural studies confirm the predicted site substitution of Gd**3** plus ions into the Ca**2** plus sites and suggest charge compensation by a cation deficiency mechanism (Ca**2** plus and/or Ti**4** plus vacancies). Evidence is presented for a significant difference between local Gd**3** plus -substituted sites and the average Ca(Gd) sites, resulting from the difference in charge and size of the two ions. A least-squares refinement of single-crystal X-ray data was carried out on (Ca//0//. //9//2//5Gd//0//. //0//7//5)TiO//3, with resulting cell parameters and major structural features within three standard deviations of those previously found for stoichiometric CaTiO//3.