The broadening of the ${}^4{\overrightarrow{T_2}}^4{A}_2$ luminescence band in ${\mathrm{Cr}}^{3+}$-doped aluminosilicate glasses is investigated experimentally and the results modeled using a technique that assumes contributions due to variation in both crystal-field strength and electron-phonon coupling. It is found that the broadening is dominated by variation in crystal-field strength in contrast to substitutionally disordered crystals studied previously in which variation in electron-phonon coupling has the larger effect. It is suggested that this behavior results because impurity ions in glasses are more easily able to influence their local environments thus ensuring more regular arrangements of nearest-neighbor anions than in crystals in which the impurity ion must fit into a predetermined lattice site. The similarities between the optical spectra of the eight different aluminosilicate glasses studied provides further evidence for this.

• Received 24 August 1998

DOI:https://doi.org/10.1103/PhysRevB.59.13712