Excitations in halogen-containing aluminosilicate optical ceramics

The reflection spectra and the excitation spectra of various emissions have been measured for Na6Al6Si6O24(NaI)(2x) and Na6Al6Si6O24(NaBr)(2x) sodalit e optical ceramics (x congruent to 0.8) by means of VUV radiation of 5-30 e V at 8 K. The analysis of these spectra revealed two groups of electronic e xcitations (EEs), The photons of hv>8.5 eV generate EEs of an aluminosilica te carcass, while 5.5 to 8.0 eV photons cause the excitation of I- and Br- ions in the cages of an aluminosilicate matrix. The luminescence of Na4I, N a4Br, Na3I and Na3Br centers has been detected at the direct optical excita tion of these centers as well as at the formation of EEs of the aluminosili cate carcass. The processes of creation, relaxation and multiplication of E Es as well as the process of VUV photochromism in sodalites are discussed, (C) 1999 Elsevier Science B.V. All rights reserved.