La2O3-CuO-TiO2 Phase Diagram and the Crystal Structure of [La0.86□0.14Cu3](Ti3.42Al0.58)O12

✍ Scribed by Mark T. Anderson; Vincent E. Balbarin; Dawn A. Groenke; Gordon A. Bain; Kenneth R. Poeppelmeier

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 389 KB
• Volume: 103
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1993.1094

✦ Synopsis

The (1 \mathrm{a}{2} \mathrm{O}{3}-\mathrm{CuO}-\mathrm{TiO}{2}) system in air at (960^{\circ} \mathrm{C}) contains two perovskite-related ternary compounds. (\mathrm{La}{2} \mathrm{CuTiO}{6}) and (\left{\mathrm{La}{2 / 3} \square_{13} \mathrm{Cu}{3}\right}\left(\mathrm{Ti}{4}\right) \mathrm{O}{12}). The former is orthorhombic, has cell parameters (a=5.587) (6), (b=5.616(5), c=7.842) (7) (\AA), is isostructural with (\mathrm{GdFeO}{3}), and exhibits Curie-Weiss magnetic behavior. The copper and titanium are statistically distribuled over one crystallographic site. The (\mathrm{La}{2} \mathrm{O}{3}-\mathrm{CuO}-\mathrm{TiO}{2}) and (\mathrm{La}{2} \mathrm{O}{3}-\mathrm{CuO}-\mathrm{SnO}{2}) syslems differ in their phase relationships, number of ternary phases, and crystal chemistry of their (\mathrm{La}{2} \mathrm{CuMO}{6}(M=\mathrm{Ti}, \mathrm{Sn})) compounds. Single crystals of |l (\left.a_{11.86}[]{0.14} \mathrm{Cu}{1}\right]\left(\mathrm{Ti}{3,12} \mathrm{Nl}{0.58}\right) \mathrm{O}{12}) were grown in an (\mathrm{Al}{2} \mathrm{O}{3}) crucible from a (\mathrm{CuO}-\mathrm{TiO}{2}) flux and crystallize in the culve space group (l m) wills (a=7.421) (1) (\dot{\hat{X}}) and (Z=2). The compound is isostructural with (\left{\mathrm{CaMn}{3}\right}\left(\mathrm{Mn}{4}\right) \mathrm{O}_{22}). The excess lanthanum in the crystal compensates the charge deficiency brought aboul by the aluminum incorpotation, and the electrostatic stabilization it affords is the principal driving force for the observed structure. (1) 1993 Acalemic Press. Inc.