Photoluminescent Properties of CoMoO_(4)Nanorods Quickly Synthesized and Annealed in a Domestic Microwave Oven

A simple way to prepare α- and β-CoMoO4 nanorods is reported in this paper. CoMoO4xH2O nanorod precursors were obtained using the microwave-assisted hydrothermal (MAH) method. By annealing the as-prepared CoMoO44xH2O precursor at 600℃ for 10 min in a domestic microwave oven, α- and β-CoMoO4 nanorods were prepared. These powders were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform Raman microscopy and ultraviolet visible absorption spectroscopy (UV-vis spectra) as well as photoluminescence (PL) measurements. Based on the results, these materials revealed nanorod morphology. PL spectra obtained at room temperature for α- and β-CoMoO4 particles exhibited maximum components around the blue light emission. The results show that the domestic microwave oven has been successfully employed to obtain α- and β-CoMoO4 nanoparticles.

Synthesis,Structural and Photophysical Properties of Gd_(2)O_(3):Eu^(3+)Nanostructures Prepared by a Microwave Sintering Process

In this paper, we report the obtention of gadolinium oxide doped with europium (Gd2O3:Eu+3) by thermal decomposition of the Gd(OH)3:Eu3+ precursor prepared by the microwave assisted hydrothermal method. These systems were analyzed by thermalgravimetric analyses (TGA/DTA), X-ray diffraction (XRD), structural Rietveld refinement method, fourrier transmission infrared absorbance spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) measurement. XRD patterns, Rietveld refinement analysis and FT-IR confirmed that the Gd(OH)3:Eu3+ precursor crystallize in a hexagonal structure and space group P6/m, while the Gd2O3:Eu3+ powders annealed in range of 500°C and 700°C crystallized in a cubic structure with space group Ia-3. FE-SEM images showed that Gd(OH)3:Eu3+ precursor and Gd2O3:Eu3+ are composed by aggregated and polydispersed particles structured as nanorods-like morphology. The excitation spectra consisted of an intense broad band with a maximum at 263 nm and the Eu3+ ions can be excitated via matrix. The emission spectra presented the characteristics transitions of the Eu3+ ion, whose main emission, , is observed at 612 nm. The photophysical properties indicated that the microwave sintering treatment favored the Eu3+ ions connected to the O-Gd linkages in the Gd2O3 matrix. Also, the emission in the Gd2O3:Eu3+ comes from the energy transfered from the Gd-O linkages to the clusters in the crystalline structure.