Vol. 40, Issue 2, pp. 427-438 (2010)

Abstract

Optical absorption, luminescence excitation, and emission spectra as well as luminescence kinetics of the Sm- and Yb-doped glasses with lithium tetraborate (Li₂B₄O₇) composition were investigated and analysed. The Sm- and Yb-doped lithium tetraborate glasses of high optical quality were obtained in air from corresponding polycrystalline compounds according to standard glass synthesis technology. The Sm and Yb impurities were added to the Li₂B₄O₇ compound in the form of Sm₂O₃ and Yb₂O₃ oxides in amount of 0.4 mol%. Using optical and electron paramagnetic resonance spectroscopy it was shown that the Sm and Yb impurities are incorporated into the lithium tetraborate glass network as Sm³⁺ (4f⁵, ⁶H_5/2) and Yb³⁺ (4f¹³, ²F_7/2) ions, exclusively. All of the observed transitions in the absorption and luminescence spectra of Sm³⁺ and Yb³⁺ centres were identified. The luminescence kinetics of the Sm³⁺ and Yb³⁺ centres in the Li₂B₄O₇ glass are characterised by a single exponential decay. Decay constants for the main emission transitions of the Sm³⁺ and Yb³⁺ centres in the lithium tetraborate glass were obtained at T = 300 K. Incorporation peculiarities and optical spectra of Sm³⁺ and Yb³⁺ ions in the lithium tetraborate glass have been discussed in comparison with other borate glasses and crystals.