Synthesis and crystal structure of a new oxychalcogenide La5Ti∼3.25Zr∼0.25S5O9.25

A new phase in the quinary system La/Ti/Zr/S/O was obtained from a mixture of La2O3, La2S3, ZrO2, and TiO2 by a solid-state reaction at 1273 K in a sealed fused-silica tube. The structure of this new phase, La5Ti∼3.25Zr∼0.25S5O9.25, was solved by single-crystal X-ray diffraction, with image for 2764 reflections (image) and 125 variables. This compound crystallizes with four formula units in the monoclinic space group C2/m with lattice constants image, image, image, and image. The structure can be viewed as a 2D building constituted from two-atom-thick slabs of rock salt type (=sulfide part) which are interleaved with double-octahedral chains centered on titanium/zirconium atoms (mixed Ti/Zr sites) and drawing a zigzag arrangement (=oxide part). In addition, EDXS analyses show that a solid solution Ti/Zr exists with a general formulation La5Ti3.5−xZrxS5O9.25 (where 0.1⩽x⩽0.5).