The Visible Fluorescence and Thermoluminescence of YAl03 Crystals Containing Er, Eu, Nd, Tb, or Yb and Other Optically Active Centers

摘要

The visible emission and uv excitation spectra for uv excitation of YAl03 containing Er, Eu, Nd, Tb or Yb and other optically active centers are measured. All emission lines from the same rare earth have the same excitation spectra with exception of two line groups for Er(3+) near 5300A. All lines broaden with increasing temperature and the fluorescence efficiency generally decreases; in some cases this is offset by a shift and broadening of the excitation peak and or by a decrease in uv induced coloration. The excitation spectra, temperature dependence of fluorescence and annealing temperatures are measured for several fluorescence bands which are associated with centers that are either stable between -196 and 1000C, uv induced and thermally annealed between -196 and 500C, or induced by heating the as-grown crystals in air to 870C. The annealing of some of the uv induced color and fluorescent centers correlates with the activation of trapped charges which cause the major part of the thermoluminescence which occurs between 300 and 400C in these crystals. The observed properties are compared with impurity levels and possible correlations are noted. (Author)