PREPARATION AND CRYSTAL-STRUCTURE OF SMTIO3CL

The compound SmTiO3Cl has been prepared by reaction of SmOCl/TiO2 (1:1) (with an admixture of small amounts of SmCl3) in evacuated silica ampoules (3 d, 800-degrees-C). Single crystals of SmTiO3Cl were obtained by chemical transport reaction (T2 --> T1; T2 = 1000-degrees-C, T1 = 900-degrees-C) using chlorine (p(Cl2, 298 K) = 1 atm) as transport agent with a sintered mixture SmOCl/TiO2 (2:3) (800-degrees-C, 5 d, evacuated silica ampoule) as starting material. SmTiO3Cl crystallizes in the monoclinic space group C2/m (No. 12) with cell dimensions a = 9.716(3) angstrom, b = 3.942(2) angstrom, c = 10.100(4) angstrom, beta = 106.63(3)-degrees and Z = 4. The structure was refined to give R = 3.8%, R(w) = 3.9%. Main building units are TiO32--layers (parallel to the (110) plain) which are connected by eightfold coordinated Sm-atoms. The relationship of this new structure type with Nd2Ta2O7Cl2 and ThTi2O6 is considered.