Luminescence and absorbance of highly crystalline CaMoO4, SrMoO4, CaWO4 and SrWO4 nanoparticles synthesized by co-precipitation method at room temperature

Highly crystalline CaMoO, SrMoO4, CaWO and SrWO4 nanoparticles were successfully synthesized by the co-precipitation of mixtures of Ca(NO3)(2)center dot 4H(2)O or Sr(NO3)(2), and Na2MoO4 center dot 2H(2)O or Na2WO4 center dot 2H(2)O dissolved in ethylene glycol at room temperature (30 degrees C). Phases, morphologies, atomic vibrations and optical properties were analyzed by X-ray diffraction, transmission electron microscopy. Fourier transform infrared and Raman spectrophotometry, and ultraviolet-visible and photoluminescent spectroscopy. All products were proved to be MXO4 (M = Ca and Sr, and X = Mo and W) with body-centered tetragonal scheelite structures, having round nanoparticles with the average sizes of 12.06 +/- 1.65, 16.40 +/- 2.44, 15.49 +/- 2.19, and 15.40 +/- 2.30 nm for CaMoO4, SrMoO4, CaWO4 and SrWO4, respectively. Their v(1)(A(g)), v(3)(B-g), v(3)(E-g), v(4)(B g), v(2)(Ag) and v(f,r,)(A(g)) vibration modes were also detected - being shifted to lower wavenumbers from MMoO4 to MWO4, due to the change of efficient atomic mass of the oscillating ions between X6+ and O2- in the [XO4](2-) complexes. Band gaps of CaMoO4, SrMoO4, CaWO4 and SrWO4 were determined to be 5.07, 3.72, 5.40, and 4.47 eV, respectively. Photoluminescent (PL) emissions were at 414, 413, 418, and 414 nm for CaMoO4, SrMoO4, CaWO4 and SrWO4, respectively. 0 2010 Elsevier BM. All rights reserved.