Spectroscopy of disordered low-field sites inCr3+: Mullite glass ceramic

In this article we present results of optical and ESR studies that have allowed us to study the behavior of ${\mathrm{Cr}}^{3+}$ at disordered low-field sites within a mullite ceramic host. The results indicate that the existence of these low-field ions, which are likely at sites in regions of disorder, accounts for most of the spectroscopic anomalies previously noted in these materials. Furthermore, energy transfer from ordered high-field to disordered low-field ions is observed. The resulting complex spectra are deconvoluted by means of the recently developed technique of saturation-resolved fluorescence spectroscopy.