Linewidth Measurements of Cr3+ in a Zinc Borate Glass

The temperature dependence of the homogeneous line width (?h) of the R-line of Cr3+ in 4ZnO·3B2O3 glass in the region between 15 K and room temperature has been measured. We found that ?h has a T2 dependence down to approximately 30 K. Below 30 K the data do not follow the power law, T2. The results are compared with those of Cr3+ in mullite and ED2 silicate glasses where the crossover was observed at about 80 K and with the data for Eu3+ in zinc borate and other glasses. The comparison indicates that the local environment affects ?h. In fact, the Cr3+ ions appear to form more defined complexes with the oxygen ligands than do the Eu3+ ions, which have a larger distribution of sites in the glass.