Electron spin resonance and optical absorption spectra of Gd 3+ ions in alkali zinc borosulphate glasses

Abstract

Electron Spin Resonance (ESR) and optical absorption spectra of Gd 3 ions in alkali zinc borosulphate glasses (Li, Na, K or Cs) containing 1 mol% Gd 3+ were studied at different temperatures (123–423 K). The ESR spectrum at room temperature exhibits three prominent features with effective g-values of 5̃.6, 2.83 and 2.02 and weaker features at g = 3.6 and 4.3. The spectra are similar to the U-spectra familiar in many oxide, fluoride and sulphate glasses, indicating very low and disordered site symmetries with a broad distribution of crystal fields. The optical absorption spectrum shows bands characteristic of Gd 3+ ions in glasses. By correlating the ESR and optical absorption data, the admixture of the excited 6P 7 2 state with the ground state 8S 7 2 has been evaluated.