UV excitation band induced novel Na^sub 3^Gd(VO^sub 4^)^sub 2^:RE^sup 3+^ (RE^sup 3+^ = Eu^sup 3+^ or Dy^sup 3+^ or Sm^sup 3+^) double vanadate phosphors for solid-state lightning applications

• Published in: Journal of alloys and compounds Vol. 739; p. 218
• Main Authors: Hussain, Sk Khaja, Giang, Tran Thi Hoai, Yu, Jae Su
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier BV 30.03.2018
• Subjects: Chemical synthesis; Chromaticity; Dysprosium; Electron transitions; Emission spectra; Europium; Excitation spectra; Gadolinium; Luminescence; Optimization; Phosphors; Photoluminescence; Quadrupole interaction; Quadrupoles; Quenching; Samarium; Sol-gel processes; Temperature dependence
• ISSN: 0925-8388

The Na3Gd(VO4)2 (NGVO):RE3+ (RE3+ = Eu3+ or Dy3+ or Sm3+) single doped phosphor materials were synthesized by a citrate-based sol-gel method. The phase formation of NGVO host lattice at different calcination temperatures was analyzed by X-ray diffraction results, which confirmed a monoclinic phase with a space group of P21/c (14). The field-emission scanning electron microscope image of the NGVO sample revealed an agglomerated morphology which was further analyzed by its corresponding energy dispersive X-ray spectrum. Under ultraviolet excitations, the photoluminescence (PL) properties of NGVO:Eu3+, NGVO:Dy3+ and NGVO:Sm3+ phosphors exhibited intense red, yellow and reddish-orange emissions at 618, 575 and 646 nm owing to their characteristic 5D0 → 7F2, 4F9/2 → 6H13/2 and 4G5/2 → 6H9/2 electronic transitions, respectively. The optimum doping concentrations of Eu3+, Dy3+ and Sm3+ ions in the NGVO host lattice were determined to be 0.09, 0.02 and 0.01 mol, respectively. Dexter's theory demonstrates that the quadrupole interactions are responsible for the concentration quenching mechanism in the NGVO:Dy3+ and NGVO:Sm3+ phosphors. Furthermore, Commission International de I'Eclairage chromaticity diagram was obtained and temperature-dependent PL emission spectra were measured for the optimal NGVO:Eu3+, NGVO:Dy3+ and NGVO:Sm3+ phosphors.