Anomalous temperature dependence of near-infrared photoluminescence band in neutron-irradiated [alpha]-Al sub(2)O sub(3)

The properties of near-infrared (NIR) photoluminescence (PL) spectra in a range of 0.8-2.8 mu m in fast neutron-irradiated [alpha]-Al sub(2)O sub(3) are reported. Anomalous temperature dependence of NIR PL spectra was observed in neutron-irradiated [alpha]-Al sub(2)O sub(3) for the first time. Highest PL intensity was measured at 260K whereas the intensity at low temperatures below 220K decreased significantly. Phonon-assisted indirect radiative recombination may be responsible for PL intensity enhancement at near room temperature. NIR PL band in a range of 0.8-2.8 mu m may be well suited for application in broadly tunable color-center laser because of its enhanced PL intensity at near room temperature.