CaMoO 4 nanopowders were prepared by the complex polymerization method. The materials were characterized by x-ray diffraction ͑XRD͒ and by Fourier transform infrared, Raman, and optical reflectance spectroscopies. The data revealed the presence of crystalline scheelite-type phase CaMoO 4 and the absence of additional phases. The surface morphology was monitored by high-resolution scanning electron microscopy ͑HR-SEM͒. The HR-SEM and XRD characterizations both revealed a tendency for the particle size to increase with rising treatment temperatures. The disordered nanopowders showed strong emission of photoluminescence, which dropped to minimal levels in the ordered nanopowders. These differences in the photoluminescence of disordered and ordered nanopowders were attributed to complex cluster vacancies.

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In this work Ba(0.99)Eu(0.01)MoO(4) (BEMO) powders were prepared by the first time by the Complex Polymerization Method. The structural and optical properties of the BEMO powders were characterized by Fourier Transform Infra-Red (FTIR), X-ray Diffraction (XRD), Raman Spectra, High-Resolution Scanning Electron Microscopy (HR-SEM) and Photoluminescent Measurements. XRD show a crystalline scheelite-type phase after the heat treatment at temperatures greater than 400 degrees C. The ionic radius of Eu(3+) (0.109 nm) is lower than the Ba(2+) (0.149 nm) one. This difference is responsible for the decrease in the lattice parameters of the BEMO compared to the pure BaMoO(4) matrix. This little difference in the lattice parameters show that Eu(3+) is expected to occupy the Ba(2+) site at different temperatures, stayed the tetragonal (S(4)) symmetry characteristic of scheelite-type crystalline structures of BaMoO(4). The emission spectra of the samples, when excited at 394 nm, presented the (5)D(1)-->(7)F(0, 1 and 2) and (5)D(0)-->(7)F(0, 1, 2, 3 and 4) Eu(3+) transitions at 523, 533, 554, 578, 589, 614, 652 and 699 nm, respectively. The emission spectra of the powders heat-treated at 800 and 900 degrees C showed a marked increase in its intensities compared to the materials heat-treated from 400 to 700 degrees C. The decay times for the sample were evaluated and all of them presented the average value of 0.61 ms. Eu(3+) luminescence decay time follows one exponential curve indicating the presence of only one type of Eu(3+) symmetry site.

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