PHOTOLUMINESCENCE SPECTROSCOPY OF CR3+ IN CERAMIC AL2O3

Photoluminescence (PL) spectroscopy is applied to study the radiative processes of ceramic Al2-xCrxO3 (0.002 less than or equal to x less th an or equal to 0.15) with the excitation light of 295 nm wavelength to gether with the optical absorption characterization by photoacoustic ( PA) spectroscopy. I (694 nm), the relative intensity of R line (simila r to 694 nm) for ceramic Al2-xCrxO3, decreases with increasing mole fr action x, indicating the concentration quenching by the increase of in teraction between Cr-3 (+) ions. I (704 nm) and I (775 nm), those of N line (similar to 704 nm) and broad band (similar to 775 nm), increase with increasing mole fraction, x, indicating the increases of pair st ate of Cr-3 (+) ions (N line) and the state by groups of more than two Cr-3 (+) ions (broad band). The ratios, I (704 nm)/I (694 nm), increa ses linearly with increasing mole fraction x up to 0.15, indicating th at it is different from the early results under the assumption that th e states of pair and groups of more than two Cr-3 (+) ions obtain some excitation by energy transfer from single ions. (C) 1998 Elsevier Sci ence S.A. All rights reserved.