Synthesis and X-Ray Diffraction Study of Potassium, Rubidium, and Cesium Polytungstates with Defect Pyrochlore and Hexagonal Tungsten Bronze Structures.-X-ray studies on the phase formation in M 2 WO 4 -WO 3 systems (M: K, Rb, Cs) verify the formation ofCs 6 W 11 O 36 and the existence of M 4 W 11 O 35 and M 2 W 7 O 22 phases. M 2 W 3 O 10 and Cs 6 W 11 O 36 possess a pyrochlore type structure whilst the structure of M 4 W 11 O 35 and M 2 W 7 O 22 resembles hexagonal tungsten bronze. Appropriate conditions for the solid phase synthesis and crystallization of discrete polytungtates from the corresponding alkali carbonate M 2 CO 3 and WO 3 are established. -(SOLODOVNIKOV, S. F.; IVANNIKOVA, N. V.; SOLODOVNIKOVA, Z. A.; ZOLOTOVA, E. S.; Neorg.

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CsPb(MoO) crystals were prepared by crystallization from their own melt, and the crystal structure has been studied in detail. At 296 K, the molybdate crystallizes in the low-temperature α-form and has a monoclinic palmierite-related superstructure (space group C2/m, a = 2.13755(13) nm, b = 1.23123(8) nm, c = 1.68024(10) nm, β = 115.037(2)°, Z = 16) possessing the largest unit cell volume, 4.0066(4) nm, among lead-containing palmierites. The compound undergoes a distortive phase transition at 635 K and incongruently melts at 943 K. The electronic structure of α-CsPb(MoO) was explored by using X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy methods. For α-CsPb(MoO), the photoelectron core-level and valence-band spectra and the XES band representing the energy distribution of Mo 4d and O 2p states were recorded. Our results allow one to conclude that the Mo 4d and O 2p states contribute mainly to the central part and at the top of the valence band, respectively, with also significant contributions throughout the whole valence-band region of the molybdate under consideration.

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