Structural, luminescent properties and chemical state analysis of YAG:Ce nanoparticle-based films

Abstract

Y3Al5O12: Ce (YAG:Ce) nanoparticles need annealing treatment at high temperature to transform the amorphous precursors to crystalline YAG phase. However, little is known about Ce chemical state analysis and photoluminescence (PL) properties of YAG:Ce nanoparticles with the different annealing temperatures and atmospheres. In this paper, amorphous nanoparticle-based YAG:Ce films, prepared by electron beam deposition technique on fused silica substrates, have been annealed at different conditions. Ce3+, Ce4+ states and Ce3+/Ce4+ atomic ratio have been distinctly separated and calculated by X-ray photoelectron spectroscopy (XPS). Combined Ce3+/Ce4+ atomic ratio with the microstructures, the Ce chemical state modification and PL properties of YAG:Ce films with different annealing treatments have been investigated throughout. Low temperature annealing in air can cause oxidation of Ce3+, higher temperature (≥750°C) annealing in air can cause partial reduction of Ce4+ due to the high-temperature pyrolysis. In this paper, value of Ce3+/Ce4+ is the maximum after 850°C annealing in H2, and YAG:Ce film annealed in H2 has the maximum luminous intensity, which could be proposed to the increased Ce3+ content. According to the systematical research and analysis, one can find that the Ce3+ content controls the luminescence efficiency. This paper provides a feasible approach to produce YAG:Ce nanoparticle-based films for the practical applications, and provides the understanding about YAG:Ce luminescent properties.