TEMPERATURE-DEPENDENCE OF HOMOGENEOUS LINE-WIDTH OF EU3+ IN BETA'-ALUMINA STUDIED BY FLUORESCENCE LINE NARROWING SPECTROSCOPY

We have measured the temperature dependence of the homogeneous spectral line width Gamma(h) of Eu3+ in beta('')-alumina, which is a typical superionic conductor, using fluorescence line narrowing spectroscopy, and have discussed dephasing mechanisms of luminescence from Eu3+ ions in this system. Due to the structural disorder in the two-dimensional conduction planes of beta('')-alumina crystals, the temperature dependences of Gamma(h) Eu3+ ion in both Beevers-Ross (BR) and mid-oxygen (mO) sites are essentially the same as those previously observed in glassy materials. However, the Eu3+ concentration as well as the temperature dependences of Gamma(h) of the Eu3+ ion in the mO site are quite different from those in the BR site. This fact strongly indicates that the dominant dephasing mechanisms of Gamma(h) of Eu3+ ion in these two sites are different from each other. This result is attributed to the intermediate nature of beta('')-alumina between ordered and disordered materials.