Role of the chemical substitution on the luminescence properties of solid solutions Ca(l-x)Cd(x)WO4 (0 ≤ x ≤1)

We have investigated the chemical substitution effects on the luminescence properties under X-ray excitation of the solid solutions Ca(l-x)Cd(x)WO4 with 0 <= x <= 1. Two types of wide spectral bands, associated with scheelite-type or wolframite-type solid solutions, have been observed at room temperature. We decomposed each spectral band into several spectral components characterized by energies and intensities varying with composition x. One Gaussian component was characterized by an energy decreasing regularly with the composition x, while the other Gaussian component was only related to the tetrahedral or octahedral configurations of tungstate groups WO42- or WO66-. The luminescence intensities exhibited minimum values in the composition range x < 0.5 corresponding to scheelite-type structures, then, they regularly increased for cadmium compositions x > 0.5 corresponding to wolframite-type structures. (C) 2015 Elsevier Ltd. All rights reserved.