Disorder and nonradiative decay ofCr3+-doped glasses

This paper describes experimental studies of the distributions of ligand field sites occupied by ${\mathrm{Cr}}^{3+}$ 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 ${}_{}{}^4{}_{}{}^{}$ ${\mathit{T}}_2$ ${\to }^4$ ${\mathit{A}}_2$ and ${}_{}{}^2{}_{}{}^{}$E${\to }^4$ ${\mathit{A}}_2$ transitions of ${\mathrm{Cr}}^{3+}$ 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 ${}_{}{}^4{}_{}{}^{}$ ${\mathit{T}}_2$ ${\to }^4$ ${\mathit{A}}_2$ broadbands of ${\mathrm{Cr}}^{3+}$ 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 ${\mathrm{Cr}}^{3+}$ ions occupying weaker crystal-field sites.