Structural and luminescent properties of BaMoO4: Gd3+phosphors prepared by microwave-hydrothermal synthesis

This work reports the synthesis of Ba1_ xMoO4:xGd3+ (x = 0, 0.01, 0.02, 0.04, 0.06, 0.08 and 0.10) powders via the co-precipitation method followed by microwave-assisted hydrothermal (MAH) treatment. X-ray diffraction (XRD) measurements revealed that the designed samples presented a single-crystalline phase and a scheelite-type tetragonal structure. The crystallite size, lattice, and atomic displacement parameters were calculated from the Rietveld refinements. The presence of vibrational groups related to BaMoO4 compounds and the disorder degree were evaluated by Raman and FTIR spectroscopy. Scanning electron microscopy (SEM) images indicated that different Gd3+ concentrations change the particle size. The band gap values determined from the UV-Vis spectra range from 4.28 to 4.33 eV. The PL spectra from pure and doped samples under four excitation wavelengths (lambda Ex) exhibit a broadband emission characteristic of radiative transitions from the MoO2_4 group and defects. The doped samples present a suppressed PL for lambda Exc= 278, 288 nm, and the calculated CIE coordinates appear in cyan. For lambda Exc= 315, 363 nm, the PL increases by more than six times for the optimal Gd3+ concentration (0.02 mol), and the CIE coordinates appear in the blue. The outcomes reveal that the incorporation of Gd3+ at optimal concentrations in BaMoO4 compounds induces the formation of defects, which has a positive effect on the host emissions.