A novel red-emitting phosphors K2Ba (MoO4)2: Eu3+, Sm3+ and improvement of luminescent properties for light emitting diodes

The novel red-emitting phosphors K2Ba(MoO4)2: Eu3+, Sm3+ were prepared by solid-state reaction and their crystal structures, photo luminescent characteristics were investigated. The results show that all samples can be excited efficiently by UV (397 nm) and blue (466 nm) light, which are coupled well with the characteristic emission from UVLED and blue LED, respectively. A small amount of Sm3+, acting as a sensitizer, increased the energy absorption around 400 nm. In the Eu3+–Sm3+ co-doped system, both Eu3+ and Sm3+ f–f transition absorptions are observed in the excitation spectra, the intensities of the main emission line (5D0 → 7F2 transition of Eu3+ at 616 nm) are strengthened because of the energy transition from Sm3+ to Eu3+. The doping concentration of Eu3+–Sm3+ was optimized. The approach to charge compensation was used: Ba2+ → Eu3+/Sm3+ + X− (X = F, Cl, and Br), and the influence of charge compensation on the luminescent intensity of phosphors is investigated.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ Graphically, it can be found that the peaks located near 592 and 616 nm originate from the transitions of Eu3+ ion from 5D0 → 7F1, 5D0 → 7F2 levels, respectively. As seen from graph, the intensity of emission spectra of K2Ba(MoO4)2: 0.10Eu3+, 0.015Sm3+ is about 2.18 times as strong as that of K2Ba(MoO4)2: 0.10Eu3+, while the intensity of emission spectra of K2Ba(MoO4)2: 0.015Sm3+ is very weak.