Singh Vijay, Seshadri M, Pathak M S, Singh N
Department of Chemical Engineering, Konkuk University, Seoul 05029, Republic of Korea.
Department of Physics, Federal University of Juiz de Fora, Juiz de Fora 36036-900, Brazil.
Spectrochim Acta A Mol Biomol Spectrosc. 2019 Jun 15;217:315-321. doi: 10.1016/j.saa.2019.03.041. Epub 2019 Mar 18.
Sm-doped vanadate-based phosphors, Ca (VO):Sm(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 Ca(VO):Sm phosphor. Observation of the photoluminescence excitation spectra revealed a broadband excitation from the distorted VO tetrahedron and a few narrow peaks from the 4f-4f intra-configuration transitions of the Sm ions. Upon 404 nm excitation, G → H (564 nm), G → H (601 nm), G → H (648 nm) and G → H (701 nm) transitions were observed. The optimum Sm concentration for the studied phosphor is 0.05 mol, and the estimated critical distance between Sm ions (R) is 19.1 Å. The observed quenching of Sm emission is attributed to the dipole-dipole interactions. The possible cross-relaxation process between neighboring Sm 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 Ca(VO):Sm phosphor could be a good candidate for the orange emitting component for wLED applications.
采用柠檬酸盐溶胶 - 凝胶法合成了掺钐钒酸盐基荧光粉Ca(VO):Sm（x = 0.005 ≤ x ≤ 0.095）。通过X射线衍射（XRD）、扫描电子显微镜（SEM）、漫反射和光致发光光谱对样品进行了表征，旨在开发用于白光发光二极管（wLED）的荧光粉转换应用。利用漫反射光谱和库贝尔卡 - 蒙克函数，计算出Ca(VO):Sm荧光粉的带隙能量为3.28 eV。光致发光激发光谱的观察结果表明，存在来自畸变VO四面体的宽带激发以及钐离子4f - 4f组态内跃迁的几个窄峰。在404 nm激发下，观察到了G→H（564 nm）、G→H（601 nm）、G→H（648 nm）和G→H（701 nm）跃迁。所研究荧光粉的最佳钐浓度为0.05 mol，估计钐离子之间的临界距离（R）为19.1 Å。观察到的钐发射猝灭归因于偶极 - 偶极相互作用。详细讨论了相邻钐离子之间可能的交叉弛豫过程。计算了所有样品的CIE坐标，它们位于CIE图的橙色区域。此外，在365 nm紫外灯下观察到了纯橙色发射。结果表明，Ca(VO):Sm荧光粉可能是用于wLED应用的橙色发光组件的良好候选材料。
