The investigation of structural and optical properties, synthesis of Sr0.5Ca0.5AO4(A:Mo, W) phosphors dopped with rare earth ions by sol-gel method

In this study, un-doped and Eu, Dy rare earth ions doped Sr0.5Ca0.5WO4 and Sr0.5Ca0.5MoO4 phosphors were successfully synthesized by sol-gel method. After the synthesis process, the structural properties of the samples were studied by X-ray diffraction (XRD), fourier transform infrared spectrometry (FT-IR), scanning electron microscope (SEM). By examining the X-ray diffraction patterns of the samples, it was observed that they have tetragonal scheelite structure in the I41 / a space group and that the doped rare earth ions have no effect on their basic crystal structure. The characteristic anti-symmetrical W – O and Mo – O stress vibrations within the groups [WO4]2- and [MoO4]2-, which are seen in the range of 750-900 cm-1 in the FT-IR spectra of the samples, support the scheelite structure. Spherical grain structure was detected in all SEM images of powder phosphors. The luminescence properties of Sr0.5Ca0.5WO4 and Sr0.5Ca0.5MoO4 powder phosphos were investigated via radioluminescence (RL), photoluminescence (PL) and thermoluminescence (TL) techniques. A broad RL emission bands in the undoped Sr0,5Ca0,5WO4 and Sr0,5Ca0,5MoO4 samples were obtained in the 400 - 750 nm and 350 - 700 nm ranges with maxima at 530 nm, respectively. In the luminescence results obtained with the doped samples, there are characteristic emission peaks of Eu3+ and Dy3+ ions. In molybdate-based samples, it was observed that the main emission of Dy3+ ions at 575 nm was significantly enhanced with increasing Eu3+ concentration. According to these results, multicolor luminescence can be obtained by changing the rare earth ion concentration in the host material.