Search

Single crystals of Ca1– хBaхF2 (x = 0.001–0.05 and 0.85–0.99) solid solutions have been grown by the Bridgman method, and their thermal conductivity has been measured in the range 50–300 K by an absolute steady-state axial heat flow technique. The thermal conductivity of all samples has been shown to decrease with increasing temperature. At 300 K, the lowest thermal conductivity of the samples with x ≤ 0.05 exceeds 6 W/(m K), and that of the samples with x ≥ 0.85 is a factor of 2 lower. [ABSTRACT FROM AUTHOR]

We have prepared ErF3-doped glasses in the ZrF4–BaF2–LaF3–AlF3–NaF system containing chlorine ions substituted for fluorine ions. The crystallization behavior of the chlorine-substituted glasses has been studied at various BaCl2 and ErF3 concentrations. We have identified phases precipitating during heat treatment of the glasses and assessed the effect of chlorine substitution for fluoride on the optical absorption and IR luminescence in the glasses. The results demonstrate that chlorine substitution for fluorine causes the UV absorption edge of the glass to shift to longer wavelengths and produces an additional absorption in the visible spectral region. The formation of crystalline phases during heat treatment of the glasses leads to significant changes in the shape of the Er3+ luminescence bands at 0.98 and 1.55 μm. [ABSTRACT FROM AUTHOR]

We report a study of upconversion luminescence in BaF2–HoF3 crystals in the visible spectral region under excitation to the 5I5 level of Ho3+ ions by laser radiation with a wavelength of 890 nm. For these excitation conditions, we propose mechanisms responsible for upconversion luminescence from the 5F3, 5S2(5F4) and 5F5 levels of Ho3+ ions. [ABSTRACT FROM AUTHOR]

We have studied luminescence and electron paramagnetic resonance (EPR) spectra of manganese- and europium-activated fluorozirconate glasses in the ZrF4–BaF2–LaF3–AlF3–NaF (ZBLAN) system and fluorohafnate glasses in the HfF4–BaF2–LaF3–AlF3–NaF (HBLAN) system in order to assess the oxidation state and spatial distribution of the activator ions. The manganese luminescence band has been shown to shift from the green (545 nm) to the red (610 nm) spectral region, and additional lines in the EPR spectrum of manganese have been observed to emerge in the EPR spectrum of manganese as a result of BaCl2 substitution for BaF2 in the ZBLAN glass. The ratio of the concentration of free activator ions to that of clustered ions has been estimated quantitatively. It has been shown that, at high doping levels, the manganese and europium ions in the glasses are predominantly clustered, and only a small part of them are present as isolated ions. [ABSTRACT FROM AUTHOR]

We have prepared glasses in the ZrF4–BaF2–LaF3–AlF3–NaF (ZBLAN) and HfF4–BaF2–LaF3–AlF3–NaF (HBLAN) systems in which fluorine anions are partially replaced by chlorine and bromine anions. Structural changes in the chlorine-substituted glasses have been investigated by Raman spectroscopy and their crystallization behavior has been studied by differential thermal analysis and X-ray diffraction. The results demonstrate a characteristic decrease in glass transition temperature (Tg) and the precipitation of fine-particle crystalline chloride and bromide phases in a temperature range well below the crystallization temperature (Tx) of the fluoride analogues. We have identified phases that crystallize during heat treatment of the glasses at various temperatures. [ABSTRACT FROM AUTHOR]