Processing thin, dense, transparent Ce:Y3Al5O12 films from flame made nanopowders for white light applications

Abstract

Flame made metal oxide nanopowders enable processing of dense, transparent thin (< 50 μm) films of Ce3+ doped Y3Al5O12 for white light applications. The addition of very small amounts of SiO2 (0.14 wt. %) and the use of a final 95:5 N2:H2 atmosphere sintering step permits nearly complete removal of pores from films originally sintered in O2. Furthermore, the introduction of this final step allows reduction in processing temperatures needed to effect Ce4+ reduction to Ce3+ by several hundred degrees below typical temperatures of >1600 °C. At 20–50 μm, the reported films are also much thinner than previously reported for the same materials normally produced by solid state reactions of micron size powders. Spectrofluorometric measurements of the dense transparent films exhibit excitation spectra centered around 450 nm and broad emission spectra in the 470–750 nm range with two peaks centered at 537 and 570 nm, confirming their applicability as a phosphor for white light emitting diodes.