Sm3+ doped calcium orthovanadate Ca3(VO4)2 - A spectral study
| Autor: | Neelam Singh, M.S. Pathak, Vijay Singh, M. Seshadri |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Photoluminescence
Chemistry Band gap Doping Analytical chemistry Phosphor 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Analytical Chemistry Photoluminescence excitation Vanadate Diffuse reflection 0210 nano-technology Spectroscopy Instrumentation |
| Zdroj: | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 217:315-321 |
| ISSN: | 1386-1425 |
| DOI: | 10.1016/j.saa.2019.03.041 |
| Popis: | Sm3+-doped vanadate-based phosphors, Ca3−x (VO4)2:Smx(x = 0.005 ≤ x ≤ 0.095), were synthesized by the citrate-based sol-gel method. The samples were characterized with XRD, SEM, diffuse reflectance and photoluminescence spectroscopy, aiming at the development of phosphor-converted wLED applications. Using diffuse reflectance spectra and the Kubelka-Munk function, the band gap energy was calculated to be 3.28 eV for the Ca2.95(VO4)2:Sm0.05 phosphor. Observation of the photoluminescence excitation spectra revealed a broadband excitation from the distorted VO4 tetrahedron and a few narrow peaks from the 4f-4f intra-configuration transitions of the Sm3+ ions. Upon 404 nm excitation, 4G5/2 → 6H5/2 (564 nm), 4G5/2 → 6H7/2 (601 nm), 4G5/2 → 6H9/2 (648 nm) and 4G5/2 → 6H11/2 (701 nm) transitions were observed. The optimum Sm3+ concentration for the studied phosphor is 0.05 mol, and the estimated critical distance between Sm3+ ions (Rc) is 19.1 A. The observed quenching of Sm3+ emission is attributed to the dipole–dipole interactions. The possible cross-relaxation process between neighboring Sm3+ ions was discussed in detail. The CIE coordinates were calculated for all the samples, and they set on the orange region of CIE diagram. In addition, pure orange color emission was observed under 365 nm UV lamp. The results suggest that the Ca3(VO4)2:Sm3+ phosphor could be a good candidate for the orange emitting component for wLED applications. |
| Databáze: | OpenAIRE |
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