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Abstract: The structure of orthorhombic rare earth titanates of La2TiO5 and Nd2TiO5, where Ti cations are in five-fold coordination with oxygen, has been studied at high pressures by X-ray diffraction (XRD), Raman scattering measurements, and quantum mechanical calculations. Both XRD and Raman results indicated two pressure-induced phase transitions during the process. An orthorhombic super cell (a×b×2c) formed at a pressure between 6 and 10GPa, and then transformed to a hexagonal high-pressure phase accompanied by partial decomposition. The hexagonal high-pressure phase is quenchable. Detailed structural analysis indicated that the five-coordinated TiO5 polyhedra remain during the formation of super cell, but the orthorhombic-to-hexagonal phase transition at high pressures is a reconstructive process, and the five-fold Ti–O coordination increased to more than 6. This phase transition sequence was verified by quantum mechanical calculations. [ABSTRACT FROM AUTHOR]

Abstract: A new high-pressure phase of U3O8, which has a fluorite-type structure, forms at pressures greater than ~8.1GPa that was confirmed by in situ x-ray diffraction (XRD) measurements. The fluorite-type U3O8 is stable at pressures at least up to ~40GPa and temperatures to 1700K, and quenchable to ambient conditions. Based on the XRD analysis, there is a huge volume collapse (>20%) for U3O8 during the phase transition and the quenched high-pressure phase is 28% denser than the initial orthorhombic phase at ambient conditions. The high-pressure phase has a very low compressibility comparing with the starting orthorhombic phase. [Copyright &y& Elsevier]

One-Dimensional (1D) MoS 2 -decorated TiO 2 nanotubes were synthesized by the anodization of TiO 2 nanotubes followed by a hydrothermal process for MoS 2 -decoration. The structure, morphology and surface characteristics of the MoS 2 -TiO 2 composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET). The results showed that TiO 2 nanotubes can be filled and covered by flake-like MoS 2 nanostructure. The numbers of the MoS 2 layers ranged from 1 to 3. The TiO 2 nanotube sensor shows a normal n-type response to reducing ethanol gas, whereas MoS 2 -TiO 2 exhibits p-type response with excellent sensing performances. Specially, the sensitivity for the MoS 2 -TiO 2 heterojunction increased almost 11 times than TiO 2 nanotubes. This conversion of sensing behavior can be explained by the formation of p-n heterojunction structures. [ABSTRACT FROM AUTHOR]

Abstract: TiO2/SiO2 composite thin films deposited on various substrates have been prepared by radio frequency magnetron sputtering from a composite target. The composite films were characterized by X-ray diffraction (XRD), atomic force microscopy, X-ray photoelectron spectroscopy and water contact angel measurements. XRD analysis indicates the amorphous structures of TiO2/SiO2 composite thin films. Contact angle results show that TiO2/SiO2 composite thin films represent natural superhydrophilicity without UV irradiation due to the enhanced acidity at SiO2–TiO2 interfaces. The heat treatment is necessary to promote thermal diffusion of Si4+ or Ti4+ cations within TiO2 or SiO2 hosts. In addition, radio frequency magnetron sputtering also may play a role in the formation of hydrophilic film surfaces. [Copyright &y& Elsevier]