Citrate-based sol-gel synthesis of blue- and green-emitting BaLa2WO7:Tm3+ or Er3+ phosphors and their luminescence properties

Abstract BaLa 2 WO 7 :Tm 3+ or Er 3+ (BLWO:Tm 3+ or Er 3+ ) single doped phosphors were prepared by a citrate-based sol-gel method. The crystalline properties of the prepared blue- and green-emitting phosphor materials were analyzed by X-ray diffraction (XRD) after annealing at 1350 °C. The XRD patterns of the both phosphors revealed monoclinic structure with a space group of P21/b. The morphological properties and elemental mappings of the BLWO:0.02Tm 3+ and BLWO:0.01Er 3+ phosphors were measured by field-emission scanning electron microscope images and energy dispersive X-ray spectrum, respectively. The photoluminescence (PL) spectra of BLWO:Tm 3+ phosphors showed characteristic emission peaks of Tm 3+ ions from the visible blue to near-infrared regions with the dominant emission at 799 nm ( 3 H 4 → 3 H 6 ) under ultraviolet (UV) and near-UV excitation wavelengths. Similarly, Er 3+ ions activated BLWO phosphors exhibited intense green emissions at 548 nm ( 4 S 3/2 → 4 I 15/2 ) under the characteristic excitation wavelength of 381 nm. Furthermore, the temperature-dependent PL emission spectra and the luminescence decay curves were measured for the optimized BLWO:0.02Tm 3+ and BLWO:0.01Er 3+ phosphors. The chromaticity coordinates for the optimized blue- and green-emitting phosphors were calculated.