Synthesis and structure determination of La8Ti10S24O4

The new compound La8Ti10S24O4 has been prepared from a mixture of La2Ti2O7 and La2O3 (in a 5:1 ratio) heated at 1200 degrees C under a H2S gas flow. This new quaternary phase was obtained due to an incomplete sulfidizing process. Single-crystal X-ray diffraction studies show that La8Ti10S24O4 crystallizes in space group P4/mmm, with Z = 1, in a cell of dimensions a = b = 10,421 Angstrom and c = 8.384 Angstrom. Least-squares refinement converged to values of R = 0.045 and R-w = 0.048. The structure can be viewed as a stacking of two types of layers along the (c) over right arrow axis, These layers are built up from infinite rutile-like chains (Ti octahedra) that cross perpendicularly. La atoms, in a tricapped prismatic coordination, are located in tunnels that develop parallel to the (c) over right arrow direction. (C) 1998 Academic Press.