Broadening of optical transitions in Cr3+-doped aluminosilicate glasses

The broadening of the T-4(2)-->(4)A(2) luminescence band in Cr3+w-doped alu minosilicate glasses is investigated experimentally and the; results modele d using a technique that assumes contributions due to variation in both cry stal-held strength and electron-phonon coupling. It is found that the broad ening is dominated by variation in crystal-held strength in contrast to sub stitutionally disordered crystals studied previously in which variation in electron-phonon coupling has the larger effect. It is suggested that this b ehavior results because impurity ions in glasses are more easily able to in fluence their local environments thus ensuring more regular arrangements of nearest-neighbor anions than in crystals in which the impurity ion must fi t into a predetermined lattice site. The similarities between the optical s pectra of the eight different aluminosilicate glasses studied provides furt her evidence for this. [S0163-1829(99)03618-8].