Crystal Growth and Structure Analysis of CeWO: A Complex Oxide Containing Tungsten in an Unusual Trigonal Prismatic Coordination Environment.

The noncentrosymmetric tungstate oxide, CeWO, was synthesized for the first time as high-quality single crystals via the molten chloride flux method and structurally characterized by single-crystal X-ray diffraction. The compound is a structural analogue to the previously reported LaWO, which crystallizes in the hexagonal space group P6̅2c. The +3 oxidation state of cerium in CeWO was achieved via the in situ reduction of Ce(IV) to Ce(III) using Zn metal. The structure consists of both isolated and face-shared WO octahedra and, surprisingly, isolated WO trigonal prisms. A careful analysis of the packing arrangement in the structure makes it possible to explain the unusual structural architecture of CeWO, which is described in detail. The temperature-dependent magnetic susceptibility of CeWO indicates that the cerium(III) f cations do not order magnetically and exhibit simple paramagnetic behavior. The SHG efficiency of LnWO (Ln = La, Ce) was measured as a function of particle size, and both compounds were found to be SHG active with efficiency approximately equal to that of α-SiO.