Luminescence properties of Cr-doped silica sol gel glasses

摘要

The emission of Cr-doped silica glass obtained by the sol- gel method is characterized by an orange broad band with a maximum at 610 nm. Its nature is examined by the absorption, excited state absorption, emission, excitation and lifetime measurements over a wide range of temperature and for different concentration of Cr ions. Our measurement show that in spite of fact that the absorption properties of Cr- doped silica sol-gel glass are predominantly associated with Cr$+4$PLU$/ centers, the observed in visible range emission can be assigned neither to Cr$+3$PLU$/ nor to Cr$+4$PLU$/ ions. The discussion of the nature of observed emission was carried out for all possible valencies of the Cr ions. In conclusion is suggested that it may be ascribed to the transitions on the monovalent Cr$+1$PLU$/ ion. The reducing agents occurring during the sol-gel process and leading to lowering the Cr valency are discussed.