For the first time the intrinsic luminescence in the undoped (CaO-Ga_{2}O_{3}-GeO_{2}) glasses with different composition has been found and investigated in the 80÷300 K temperature range. The new glasses of high chemical purity and optical quality with stoichiometric composition similar to that in calcium-gallium- germanium garnet (Ca_{3}Ga_{2}Ge_{3}O_{12}), trigonal Ca-gallogermanate (Ca_{3}Ga_{2}Ge_{4}O_{14}), and Ca_{3}Ga_{2}O_{6} crystals were obtained by the high-temperature synthesis method. The luminescence and photoexcitation spectra analysis, supported by EPR spectroscopy data, yields the following results: (i) the UV-excited non-elementary broad emission band with maxima at roughly 500 nm and 420 nm in the (CaO-Ga_{2}O_{3}-GeO_{2}) glasses is due to recombination of ensemble of the transient hole O^{-} centres; (ii) the emission bands with maxima at nearly 380 and 710 nm, which were distinctly revealed in glasses with the Ca_{3}Ga_{2}Ge_{4}O_{14} and Ca_{3}Ga_{2}O_{6} compositions, are assigned to the luminescence of UV-induced electron centres of two different types. Possible models of the luminescence centres in (CaO-Ga_{2}O_{3}-GeO_{2}) glass network are discussed.
The electron paramagnetic resonance spectra of the glasses with Li_{2}B_{4}O_{7} and KLiB_{4}O_{7} compositions doped with Mn and Cu were investigated. On the basis of obtained EPR spectra analysis it was shown that the Mn and Cu impurities are incorporated into the glass network as Mn^{2+} (^{6}S_{5/2}, 3d^{5}) and Cu^{2+} (^{2}D_{5/2}, 3d^{9}) ions. The Mn^{2+} EPR spectra in the glasses with Li_{2}B_{4}O_{7} and KLiB_{4}O_{7} compositions are characterised by the following parameters, measured at T = 300 K: isotropic g-factor (g_{iso} = 2.00 ± 0.05), isotropic hyperfine constant (A_{iso} = (8.65 ± 0.05) mT) and peak-to-peak linewidth of hyperfine components ΔB_{pp} = (3.50 ± 0.05) mT. The Cu^{2+} EPR spectra in the glasses with Li_{2}B_{4}O_{7} and KLiB_{4}O_{7} compositions, registered at T = 300 K are characterised by the same g-values (g_∥ = 2.34 ± 0.05, g_⊥ = 2.06 ± 0.05) and peak-to-peak line width of hyperfine components (ΔB_{pp}^{∥} = (5.11 ± 0.05) mT, ΔB_{pp}^{⊥} = (1.80 ± 0.05) mT), whereas anisotropic hyperfine constants show some differences (A_{∥} = (14.28 ± 0.05) mT, A_{⊥} = (2.34 ± 0.05) mT for glass with Li_{2}B_{4}O_{7} composition and A_{∥} = (14.21 ± 0.05) mT, A_{⊥} = (2.55 ± 0.05) mT for glass with KLiB_{4}O_{7} composition). The possible local structure of the Mn^{2+} and Cu^{2+} centres in the lithium and potassium-lithium tetraborate glass network has been considered.
Optical absorption, emission and luminescence kinetics of Nd^{3+} centres in the new borate crystal with Sr_{4}B_{14}O_{25}:Nd (Nd content 0.2 wt.%) composition are investigated and analysed. The oscillator strengths (P_{theor} and P_{exp}) for observed absorption transitions and phenomenological intensity parameters Ω_t (Ω_2=1.59×10^{-20} cm^{-1}, Ω_{4} = 2.06 × 10^{-20} cm^{-1}, and Ω_{6} = 2.28 × 10^{-20} cm^{-1} were calculated based on the standard Judd-Ofelt theory. Using Ω_t parameters the radiative transitions rates (W_{r}), branching ratios (β) and radiative lifetime (τ_{rad}) for Nd^{3+} centres in the Sr_{4}B_{14}O_{25}:Nd crystal were calculated and analysed. Measured lifetime (τ_{exp} = 105 and 93 μs at T = 10 and 300 K, respectively) is compared with this calculated (τ_{rad} = 331 μs) and quantum efficiency for Nd^{3+} centres from ^{4}F_{3/2} emitting level in the Sr_{4}B_{14}O_{25}:Nd crystal is estimated (η ≅ 30%). Incorporation peculiarities and local structure of Nd^{3+} luminescence centres in the Sr_{4}B_{14}O_{25} crystal and corresponding glass with 4SrO-7B_{2}O_{3} composition are discussed on the basis of referenced X-ray diffraction data and presented results.
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