Local structures in ceria-based materials were investigated by UV resonance Raman spectroscopy using a 363.8 nm laser line for the first time. In the spectra of a highly crystalline and undoped ceria, overtone LO series are clearly detected due to the multiphonon relaxation by the UV resonance Raman effect. Gd 3+ doping in ceria additionally activates the disorder bands that are attributable to lattice spaces with or without an oxygen vacancy. The crystal size dependency of the UV Raman spectra suggests that Ce 3+ ions preferably form the MO 8 -type (M ) Ce 3+ ) complex in the undoped ceria nanoparticles and are eliminated by oxidation while heating in air. Gd 3+ ions also tend to form a MO 8 -type complex in the nanocrystalline ceria matrix. However, they diffuse to form the more thermodynamically stable defect clusters that accompany the grain growth upon heating.

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The photocatalytic degradation of indigo carmine dye was studied using hydrothermally prepared TiO 2 impregnated activated carbon (TiO 2 : AC). A comparison between the degradation of the indigo carmine dye using commercial TiO 2 and TiO 2 : AC revealed the efficiency of the title compound. The degradation reaction was optimized with respect to the dye concentration and catalyst amount. The reduction in the chemical oxygen demand (COD) revealed the mineralization of dye along with colour removal. The active compound like TiO 2 was impregnated onto the activated carbon surface under mild hydrothermal conditions (< 250°C, P ~ 40 bars). The impregnated activated carbon samples were characterized using powder X-ray diffraction (XRD) and scanning electron microscope (SEM).

A zinc oxide (ZnO) rod array was deposited on a nonseeded glass substrate at 90 °C by using a spin-spray technique. This technique is a solution process using selective heterogeneous nucleation of ZnO crystals on the substrate, and it eliminates homogeneously nucleated particles that degrade film quality. These features are an obvious progress for solution routes which essentially involves heterogeneous nucleation on seed layer and homogeneous nucleation in solution. In this study, we prepared a ZnO rod array by spin-spray on a nonseeded glass substrate and analyzed the formation mechanism.