Abstract
The thermal degradation is one of the key problems that restricting the working properties and lifetime of Y3Al5O12:Ce3+ phosphor for white light-emitting diode (LED) application. To clarify its thermal degradation mechanism, a heat-treatment process was carried out, and the effects of heat-treatment temperature on the luminescent intensity and micro-structure changes were investigated. Based on the evidences about micro-structural distortion detected by XRD, IR, TL and XPS, the relationship between luminescent intensity and micro-structure change was founded, and a micro-structural distortion mechanism on the thermal degradation was proposed. The emission intensity decreased with the increasing heat-treatment temperature, which was an accelerated thermal degradation. The intensities of two thermoluminescence peaks at 112 °C and 248 °C also decreased with the increasing heat-treatment temperature and towards zero. This indicated that the corresponding defects levels were gradually eliminated and a micro-structural distortion occurred. X-ray photoelectric spectroscopy results showed small part of trivalent cerium ions were oxidized to tetravalent cerium ions, and alumina tetrahedral were gradually transformed into alumina octahedron. Therefore, the thermal degradation was jointly caused by the oxidation of Ce3+ and the distortion of micro-structure.
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