Electron paramagnetic resonance and optical absorption spectra of Gd3+ ions in alkali cadmium borosulphate glasses

Electron paramagnetic resonance (EPR) at 9.205 GHz is examined for a series of Gd3+‐doped alkali cadmium borosulphate (R2SO4 · CdSO4 · B2O3; R = Li, Na, K or Cs) glasses. 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. Remarkable changes are observed in the spectrum with changes in temperature, glass composition, and concentration of Gd3+ ions. Optical absorption spectra of Gd3+‐doped cadmium borosulphate glass are also studied at 300 K.