[en] Different concentrations of ErF/sub 3/ and HoF/sub 3/ ranging from 0.1 to 1.5 wt. % have been doped to an AlF/sub 3/-based glass with composition (mol %) 3.2 AlF/sub 3/ - 10.6 BaF/sub 2/ - 20.2 CaF/sub 2/ - 8.3YF/sub 3/ - 3.5 MgF/sub 3/ - 3.8 NaF - 13.2 SrF/sub 2/ - 10.2 ZrF/sub 4/. The values of Avrami exponent, n, and activation energy, E, for the base glass as well as the doped glasses have been calculated by analysing differential scanning calorimetric data according the the amended Ozawa-Chen and Augis and Benett equations. In the light of these results we observe that the introduction of suitable amount of rare-earth ions improved the thermal stability of the base glass. (author)

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[en] Fluoroindate glasses containing 1, 2 and 3, ErF₃+YbF₃ mol% were prepared in a dry box under argon atmosphere. The optical absorption and photoluminescence spectra have been measured as a function of the temperature in the range from 15 to 300 K. The absolute intensities of the transitions observed in the optical spectra have been interpreted in terms of transitions within 4f^N configurations. The energy matrices resulting from the combination of free-ion terms with the crystal field were diagonalized. Excellent correlations were obtained between experimental transition energies and computed level structures. Phenomenological Ω_λ intensity parameters for Er⁺³and Yb⁺³ ions in fluoroindate glass were also calculated using the standard theory of Judd-Ofelt. Good agreement was obtained between the experimental oscillator strengths determined from the area under the absorption band and the calculated ones. The splitting of the Er⁺³ ground state was determined from the analysis of photoluminescence spectra

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[en] Using the methods of differential thermal and X-ray phase analyses the systems BeF₂-ErF₃ and Rb₂BeF₄-RbEr₂F₇ have been studied. It is established that the system BeF₂-ErF₃ is attributed to the eutectic type; the system Rb₂BeF₄-RbEr₂F₇ presents quasibinary cross section of the eutectic kind of the ternary system RbF-BeF₂-ErF₃. Composition and melting points of the eutectics are determined

[en] Thermal properties of ErF₃ at high temperatures, liquid state inclusively, melting-crystallization and solid-state transition ranges were studied by the method of samples examining with a narrow gamma beam. The density and volumetric factor of liquid erbium fluoride thermal expansion at he melting point amount to 6092±30 kg/m³ and (15.1±0.5)x10^-5 K. Relative differences in density during melting and polymorphous transformation are equal to 0.75±0.1 and 16.9±1.3% respectively. The data obtained as a result of the study and literature data permit ascertaining the regularities in the change of thermal properties in the series of heavy rare earth fluorides (ErF₃-LuF₃)

[en] Phase diagrams formed by sodium fluorides with Tb, Dy, Er trifluorides, were investigated by methods of differential thermal and X-ray phase analyses of annealed and quenched samples. Three types of intermediate phases of Na_0.5-xR_0.5-+xF_2+2x variable composition were revealed: high-temperature phases with fluorite structure (x = 0.49-0.66±0.015), which are transformed to phases with gagarinite structure at cooling (x 0.51-0.545±0.015); in the vicinity of RF₃ (R = Tb, Dy) compositions-high-temperature phases with proposed structure of LaF₃-tisonite type. Ordered fluorite-like low-symmetrical phase of composition similar to NaEr₂F₇ was revealed in ErF₃ system in a narrow temperature range. 30 refs.; 2 figs.; 3 tabs