L. N. Dmitruk

Glass Transition and Crystallization of Glasses Based on Rare-Earth Borates

The glass formation is investigated and the highest contents of rare-earth oxides are determined in glasses of the Ln2O3–B2O3 system in the composition region (Ln2O3)1 + x · 3B2O3 (Ln = La, Nd, Gd, Er, Dy, Yb, Lu; 0 ≤ x ≤ 0.8). It is shown that the total content of rare-earth oxides in the La2O3–Ln2O3–B2O3 ternary system can substantially exceed their highest content in the binary systems. The devitrification of glasses in the La2O3–Ln2O3–B2O3 system at temperatures above the glass transition point Tg is analyzed.

Barium borate glass and transparent glass ceramics doped with Pb4Lu2YbF17

Barium borate glasses doped with complex Pb4Lu2YbF17 fluoride have been synthesized and investigated. Heat treatment produced glass ceramics containing the crystalline BaF2:Yb3+ phase. The changes in the structural and optical properties of the glass ceramics were revealed by X-ray diffraction, Raman spectroscopy, and luminescence spectroscopy of Yb3+ ions in polycrystalline Pb4Lu2YbF17, initial glass, and glass ceramics.

VUV 5d-4f luminescence of Gd3+ and Lu3+ ions in the CaF2 host

The first observation and characterization of Lu3+ 4f135d-4f14 luminescence from the CaF2: Lu3+ crystal are reported, and the multisite structure in the spectra of Ce3+, Gd3+, and Lu3+ ions in the CaF2 host is analyzed with the high-resolution VUV spectroscopy technique using synchrotron radiation. It is shown that vibronic structure in the emission and excitation spectra of interconfigurational transitions in Gd3+ and Lu3+ ions doped into CaF2 differs from that observed for Ce3+ ions entering mainly at the tetragonal (C4v) sites. However, the exact types of sites in which the Gd3+ and Lu3+ ions reside in a CaF2 lattice cannot be identified using only the obtained experimental spectroscopid data.

Preparation and properties of heavy-metal halide glasses

We have studied the effect of In3+, Pb2+, Gd3+, and Cl (heavier ions) substitutions for Al3+, Ba2+, La3+, and F− on the crystallization stability and UV/IR optical properties of HBLAN fluorohafnatc glasses (HfF4-BaF2-LaF3-AlF3-NaF system). We obtained stable glasses containing InF3 and BaCl2 instead of AlF3 and BaF2, respectively, and offering increased IR transmission. The presence of CCl4 in the process atmosphere and the removal of oxygen-containing impurities via directional solidification are shown to have an advantageous effect on the optical quality of the glasses. The fluoride-chloride glasses are capable of accommodating about 1.5 times higher levels of rare-earth activators in comparison with their fluoride analogs.

Spectroscopic studies of glasses based on rare-earth borates

Raman light scattering and Nd3+ luminescence are investigated in glasses based on rare-earth borates with a high content of the rare-earth oxide and subjected to annealing. It is established that, during annealing, structural relaxation brings about the formation of phases with a structure similar to the structure of rare-earth orthoborates and oxoborates. This leads to considerable changes in the characteristics of Nd3+ luminescence.

Scintillating Fluorohafnate Glasses

Data are presented on the roentgenoluminescence and gamma-radiation resistance of Ce3+-doped fluorohafnate glasses prepared under different redox conditions and containing different additions. The glasses are shown to contain several types of luminescence centers and radiation-induced color centers, whose concentrations are governed by the preparation conditions and the nature of the dopants. The radiation resistance and light output of the glasses can be notably enhanced by optimizing the preparation conditions and introducing certain additions.

Synthesis and investigation of Ag-Cs-X (X = I, Br, Cl) glasses doped with Er3+

The glass formation and crystallization of ErI3-doped melts in the Ag-Cs-Pb-X (X = I, Br, Cl) are investigated in the section corresponding to the cation ratio Ag: Cs: Pb = 59: 39: 2 with ErI3 contents of 0.2–7.5 mol %. The glass transition, crystallization, and melting temperatures are determined for a number of compositions. The primary crystalline phases that precipitate from melts upon crystallization are identified. It is demonstrated that the iodide, bromide, and chloride glasses containing up to 0.5 mol % ErI3 have the lowest crystallization ability. An increase in the ErI3 content leads to the precipitation of unidentified erbium-containing phases from melts upon cooling and to an increase in the crystallization ability of glasses. The spectral and luminescence properties of the glass of the composition 52Ag · 17AgCl · 39CsBr · 2PbCl2 + 0.5 mol % ErI3 are studied in the range of the 4I13/2 → 4I15/2 transition of the Er3+ ion. It is found that the lifetime of the 4I13/2 → 4I15/2 level of the Er3+ ion is equal to 10 ms.

Intrinsic X-ray Luminescence of Fluorohafnate Glasses

The influence of the atmosphere used in glass synthesis and dopants on X-ray luminescence of fluorohafnate glasses in the HfF4–BaF2–Ce(La)F3–AlF3–NaF–InF3 system is investigated. Upon introduction of certain oxides, the X-ray luminescence spectrum exhibits a broad band with a maximum at 360 nm. A similar band appears in the spectra in the case when the glasses are synthesized under reducing conditions. The appearance of the 360-nm luminescence band is observed both in the spectra of glasses activated by cerium and in the spectra of nonactivated glasses. It is assumed that the appearance of this band is associated with the formation of Hf3+ ions and fluorine vacancies in the glass under investigation.