The perovskite-type structures of DyAlO₃, DyFeO₃and some related lanthanon mixed oxides

Abstract

The perovskite type structures of selected lanthanonmixed oxides (LnBO/ sub 3/) were investigated to determine the factors which influence their distortion. Lanthanum, neodymium, gadolinium, and dysprosium, which have a suitable range of ionic radii, were chosen for the tripositive Ln ions. Aluminum, iron, and gallium, which have tripositive ions with an inert gas, half- filled d-shell, and 18-electron configuration, respectively, were chosen as B ions that would demonstrate the influence of partial covalent character of B-O linkages on the distortion. Complete reactions to perovskite type oxides were obtained in all cases except Gd/sub 2/O/sub 3/ + Ga/sub 2//sup O/ub 3/, and Dy/ sub 2/O/sub 3/ + Ga/sub 2/O/sub 3/. The data sho wed that>s distortion increased with the lanthanide contraction in each of the series LnAlO/sub 3/, LnFeO/sub 3/, and LnGaO/sub 3/. The orthorhombic structures of DyAlO/sub 3/ and DyFeO/sub 3/ are described. (B.O.G.)