Photoacoustic spectroscopy of Cr3+ in Ceramic Al2O3

Photoacoustic (PA) spectroscopy is applied to study the heat generation by nonradiative processes of ceramic Al2O3 containing 5 mol% m Cr3+ ions in the wavelength range of 330–800 nm with a modulation frequency of 133 Hz. PA spectroscopy is provided to get optical absorption spectra for opaque samples such as ceramics, and the peaks which correspond to U-band and Y-band can be observed. The PA phase ratio. S (Y-band)/S (U-band), increases sintering time, indicating the decrease of non-radiative processes at the 2E→4A2 transition. The PA phase ratio φ (Y-band)/ φ (U-band), also increases and approaches to unity with increasing sintering time, and therefore the time lag of the PA signal generation of Y-band gradually approaches to that of U-band, indicating the correlation between PA phase and ceramic quality. The sintering time dependence of fluorescence quantum efficiency and fluorescence lifetime increase with increasing sintering time.