Micropowder Ca 2 YMgScSi 3 O 12 :Ce Silicate Garnet as an Efficient Light Converter for White LEDs.

This work is dedicated to the crystallization and luminescent properties of a prospective Ca 2 YMgScSi 3 O 12 :Ce (CYMSSG:Ce) micropowder (MP) phosphor converter (pc) for a white light-emitting LED (WLED). The set of MP samples was obtained by conventional solid-phase synthesis using different amounts of B 2 O 3 flux in the 1-5 mole percentage range. The luminescent properties of the CYMSSG:Ce MPs were investigated at different Ce 3+ concentrations in the 1-5 atomic percentage range. The formation of several Ce 3+ multicenters in the CYMSSG:Ce MPs was detected in the emission and excitation spectra as well as the decay kinetics of the Ce 3+ luminescence. The creation of the Ce 3+ multicenters in CYMSSG:Ce garnet results from: (i) the substitution by the Ce 3+ ions of the heterovalent Ca 2+ and Y 3+ cations in the dodecahedral position of the garnet host; (ii) the inhomogeneous local environment of the Ce 3+ ions when the octahedral positions of the garnet are replaced by heterovalent Mg 2+ and Sc 3+ cations and the tetrahedral positions are replaced by Si 4+ cations. The presence of Ce 3+ multicenters significantly enhances the Ce 3+ emission band in the red range in comparison with conventional YAG:Ce phosphor. Prototypes of the WLEDs were also created in this work by using CYMSSG:Ce MP films as phosphor converters. Furthermore, the dependence of the photoconversion properties on the layer thickness of the CYMSSG:Ce MP was studied as well. The changes in the MP layer thickness enable the tuning of the white light thons from cold white/daylight to neutral white. The obtained results are encouraging and can be useful for the development of a novel generation of pcs for WLEDs.