Pressure-Stimulated Synthesis and Luminescence Properties of Microcrystalline (Lu,Y)3Al5O12:Ce3+ Garnet Phosphors

The Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 phosphors were synthesized by solid state reaction at temperature 1623 K and pressure 1.5 X 10(7) Pa in (95% N-2 + 5% H-2) atmosphere. Under the conditions, the compounds crystallize in the form of isolated euhedral partly faceted microcrystals similar to 19 mu m in size. The crystal structures of the Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 garnets have been obtained by Rietveld analysis. The photoluminescence (PL) and X-ray excited luminescence (XL) spectra obtained at room temperature indicate broad asymmetric bands with maxima near 519 and 540 nm for Y2.99Ce0.01Al5O12 and Lu2.98Ce0.01Y0.01Al5O12, respectively. The light source was fabricated using the powder Lu2.98Ce0.01Y0.01Al5O12 phosphor and commercial blue-emitting n-UV LED chips (lambda(ex) = 450 nm). It is found that the CIE chromaticity coordinates are (x = 0.388, y = 0.563) with the warm white light emission correlated color temperature (CCT) of 6400 K and good luminous efficiency of 110 lm/W.