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

Abstract

Highly crystalline CaMoO4, SrMoO4, CaWO4and SrWO4nanoparticles were successfully synthesized by the co-precipitation of mixtures of Ca(NO3)24H2O or Sr(NO3)2, and Na2MoO42H2O or Na2WO42H2O dissolved in ethylene glycol at room temperature (30 °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, CaWO4and SrWO4, respectively. Their ν1(Ag), ν3(Bg), ν3(Eg), ν4(Bg), ν2(Ag) and νf.r.(Ag) vibration modes were also detected - being shifted to lower wavenumbers from MMoO4to 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, CaWO4and SrWO4were 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, CaWO4and SrWO4, respectively. © 2010 Elsevier B.V. All rights reserved.