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A simple low-temperature solid-state reaction in the presence of the surfactant PEG400 was developed to obtain ZnO/CdS nanocomposites. The effects of synthesis temperature and reaction time on crystal structure and optical properties of the nanocomposites were investigated by several technologies. X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM) characterizations showed that the products consisted of the nanoparticles, and the grain growth kinetics of the cubic CdS and the hexagonal ZnO phase in the nanocomposites was described. The mechanism analysis suggested that sufficient grinding and heating treatment was a key to form the ZnO/CdS nanocomposites, and the surfactant PEG400 was proved not to involve the reaction and prevent the nanoparticles from aggregating to larger in whole grinding and heat-treatment process. Ultraviolet–visible (UV–vis) spectra revealed that the band gaps of the nanocomposites could be tuned by the reaction temperature and reaction time. Photoluminescence (PL) spectra showed that the changing position and the intensity of the emission peaks resulted from the rate of electron transfer and recombination probability under the different conditions. [ABSTRACT FROM AUTHOR]

Abstract: Yttrium aluminum garnet (YAG) powders were synthesized by a solvothermal method under mild conditions with inexpensive aluminum and yttrium nitrates as the starting materials, and the ethylenediamine (EDA) solution as the solvent. Hydroxide precursors were synthesized by two different precipitating processes, in which urea or ammonium hydrogen carbonate was used as precipitant. The formation of YAG particle was investigated by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM results showed that spherical YAG powders were successfully synthesized when ammonium hydrogen carbonate was used as precipitant. [Copyright &y& Elsevier]