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

The high optical quality glasses with CaB4O
7
:Tb, LiCaBO
3
:Tb, CaB
4
O
7
:Dy, and LiCaBO
3
:Dy compositions containing 0.5 and 1.0 mol. % Tb
2
O
3
and Dy
2
O
3
have been obtained. By electron paramagnetic resonance (EPR) and optical spectroscopy it was shown that the Tb and Dy impurities are incorporated in the CaB
4
O
7
and LiCaBO
3
glass network as Tb
³⁺
(4f
⁸
,
⁷
F
6
) and Dy
³⁺
(4f
⁹
,
⁶
H
15/2
) ions, exclusively. All observed f - f transitions of Tb
³⁺
and Dy
³⁺
centres in optical absorption, luminescence excitation and emission spectra have been identified. Luminescence kinetic shows single exponential decay for Tb
³⁺
and Dy
³⁺
centres in the CaB
4
O
7
and LiCaBO
3
glasses. Lifetimes for main emitting levels of Tb
³⁺
and Dy
³⁺
centres in all investigated glasses were determined at T = 300 K. Spectroscopy shows that obtained glasses are promising luminescent materials.