Disorder and nonradiative decay of Cr3+-doped glasses

This paper describes experimental studies of the distributions of ligand field sites occupied by Cr3+ dopant ions in inorganic glasses with different chemical compositions. The effects of site-to-site disorder are observed via the steady-state spectral band-shape and decay patterns of 4T24A2 and 2E4A2 transitions of Cr3+ ions and their temperature dependences. The temperature dependence of the emission band shape, calculated on the assumption that the disorder distribution function is a Gaussian, agrees well with the experimental results. In addition, the peak wavelengths of the 4T24A2 broadbands of Cr3+ in different glasses are shifted to shorter wavelengths with increasing temperature, and the total intensities of the bands are reduced. These results are explained in terms of nonradiative decay of Cr3+ ions occupying weaker crystal-field sites.