Luminescence Quantum Efficiency of Gd and Tb in Borate Glasses and the Mechanism of Energy Transfer between Them

Abstract

A study of the quantum efficiency of the luminescence of gadolinium and terbium in borate glasses and of the energy transfer between these ions is presented. From our measurements of fluorescence decay times, absorption, fluorescence, and excitation spectra, we calculated the fluorescence quantum yield of the ⁶P_7/2 gadolinium and the ⁵D₄ terbium levels on excitation to higher gadolinium and terbium levels, respectively. The energy transfer rates between gadolinium and terbium in borate glasses were calculated on the basis of the above measurements. These measurements were performed for gadolinium and terbium concentrations ranging from 0 to 4 wt%. Our results show that the energy transfer occurs mainly between the ⁶P_7/2 gadolinium level and (⁵D₀, ⁵H₇) terbium levels and is due to a dipole‐dipole interaction. It is concluded that the energy transfer between gadolinium and terbium is a phonon assisted process.