New effective luminescent materials based on the Sm-doped borate glasses
Advanced Materials Letters,
2017, Volume 8, Issue 6, Pages 723-734
AbstractThe spectroscopic and radiative properties of the Sm-doped borate glasses with Li2B4O7, LiKB4O7, CaB4O7, and LiCaBO3 basic compositions as new luminescent materials have been investigated and analysed. The borate glasses of high chemical purity and optical quality, doped with Sm2O3 in amounts of 0.5 and 1.0 mol. % were obtained from corresponding polycrystalline compounds in the air atmosphere using standard glass synthesis technology. The spectroscopic properties of obtained Sm-doped glasses were studied using electron paramagnetic resonance (EPR), optical absorption, photoluminescence, and decay kinetics techniques. The Judd–Ofelt theory had been used for analysis of the optical absorption spectra and calculation of the phenomenological intensity parameters (Ω2, Ω4, Ω6). Radiative properties such as transition probabilities (Arad), branching ratios (βexp < /sub> and βrad), stimulated emission cross-sections (σe), and radiative lifetimes (τrad) were estimated for 4 G5/2 → 6 HJ (J = 5/2, 7/2, 9/2, and 11/2) emission transitions of the Sm 3+ ions in the Li2B4O7:Sm, CaB4O7:Sm, and LiCaBO3:Sm glasses containing 1.0 mol. % Sm2O3. The luminescence kinetics of Sm 3+ centres in the investigated glasses are characterised by a single exponent decay with typical lifetimes, which depend on the basic glass composition and Sm impurity concentration. Experimental lifetimes (τexp < /sub>) have been compared with those calculated (τrad) and quantum efficiencies (η) of the Sm 3+ emission transitions were estimated. The calculated high quantum efficiencies (~ 80 %) and measured high quantum yields of luminescence (~ 14 – 21 %) clearly show that the investigated glasses belong to very promising materials for luminescent and laser applications.
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