Synthesis and optical spectroscopy of borate glasses, doped with terbium and dysprosium

The high optical quality glasses with CaB4O7:Tb, LiCaBO3:Tb, CaB4O7:Dy, and LiCaBO3:Dy compositions containing 0.5 and 1.0 mol. % Tb2O3 and Dy2O3 have been obtained. By electron paramagnetic resonance (EPR) and optical spectroscopy it was shown that the Tb and Dy impurities are incorporated in the CaB4O7 and LiCaBO3 glass network as Tb³⁺ (4f⁸, ⁷F6) and Dy³⁺ (4f⁹, ⁶H15/2) ions, exclusively. All observed f - f transitions of Tb³⁺ and Dy³⁺ centres in optical absorption, luminescence excitation and emission spectra have been identified. Luminescence kinetic shows single exponential decay for Tb³⁺ and Dy³⁺ centres in the CaB4O7 and LiCaBO3 glasses. Lifetimes for main emitting levels of Tb³⁺ and Dy³⁺ centres in all investigated glasses were determined at T = 300 K. Spectroscopy shows that obtained glasses are promising luminescent materials.