Morphological Stability of the Solid–Liquid Interface during Melt Crystallization of Ca1–xSrxF2 Solid Solution

Crystallography Reports - Proceeding from the phase diagram of the CaF2–SrF2 system, the stability of crystal–melt interface of solid solution against constitutional supercooling has...     

Phase diagram of the NaF–CaF<Subscript>2</Subscript> system and the electrical conductivity of a CaF<Subscript>2</Subscript>-based solid solution

The phase diagram of the NaF–CaF₂ system was studied by thermal analysis and X-ray powder diffraction analysis with the determination of the chemical composition. The system was found to be of the eutectic type. A narrow range of the existence of solid solution Ca_1–xNa_xF_2–x was established. The NaF solubility reaches a maximal value of x = 0.035 at 1200 ± 50°C (the temperature at which there is a diffuse phase transition in fluorite). At 920 ± 25°C, the NaF solubility reaches a minimum (<0.4 mol %) and increases again to 2.2 ± 0.2 mol % at a eutectic temperature (818°C). The ionic conductivity increases by three orders of magnitude after adding NaF to CaF₂.     

Structural Transformation of a (1 – x)Fe2O3–xRuO2 Nanosystem at Different Reduction Temperatures

Technical Physics - The phase composition and structure of oxide and hydrogen-reduced iron–ruthenium systems are studied using conversion and adsorption Mössbauer spectroscopy, as well...     

A method of determining the strength of silver-coating adhesion to a silicon support using glue

A technique of evaluating the strength of silver-coating adhesion to a silicon support in order to determine the quality of contact connections in semiconductor elements is developed. The best variant is shown to be application of the high-strength film glue VK-51 and special unit with molybdenum thermocompensators.     

Intensity parameters for Er<Superscript>3+</Superscript> ions in calcium-niobium-gallium garnet crystals

Based on the analysis of the absorption spectra of Er-doped calcium-niobium-gallium garnet (Er:CNGG) crystals according to the Judd-Ofelt theory, the intensity parameters for these crystals are determined to be Θ₂ = 3.43 × 10^?20 cm² Θ₄ = 1.20 × 10^?20 cm², and Θ₆ = 0.58 × 10^?20 cm². The parameters found are compared with the intensity parameters for other laser oxide crystals. Using these intensity parameters, the probabilities of radiative transitions between the energy levels of Er³⁺ ions in CNGG crystals and the luminescence branching ratios β_JJ’ are calculated. From the measured lifetime of the ⁴ I _11/2 level of Er³⁺ ions (τ = 626 μs) and the probability of the radiative transition from this level (A = 192 s^?1), it is found that about 88% of the excitation energy in the Er:CNGG crystals is nonradiatively transferred from the ⁴ I _11/2 to the ⁴ I _13/2 level. It is suggested that an increase in the oscillator strength and in the line strength of the ⁴ I _15/2 → ² H _11/2 transition of Er³⁺ in CNGG crystals, as well as an increase in the intensity parameter Θ₂ with respect to the corresponding parameters for other garnet crystals are caused by the existence in CNGG crystals of Er³⁺ centers with the environment symmetry lower than D ₂.     

Studying the microstructure of AlSiC metal matrix composite material by scanning electron microscopy

The microstructure of fractures in AlSiC metal matrix composite material obtained via vacuum compression impregnation of porous semi-finished materials is studied using a Quanta 200i 3D FEI scanning electron microscope. The disruption of AlSiC samples is shown to be due to the brittle fracturing of the largest grains of silicon carbide and disruption (during plastic deformation) of the material of the matrix alloy located between the grains of the filler. The character of SEM images testifies to considerable adhesion of selected aluminum matrix alloys at matrix-filler interfaces and the high mechanical strength of the material under study.     

Laser damage threshold of hydrophobic up-conversion carboxylated nanocellulose/SrF2:Ho composite films functionalized with 3-aminopropyltriethoxysilane

Cellulose - Luminescent nanocomposite films, containing SrF2:Ho up-conversion particles, were prepared by two different protocols from aqueous dispersions of TEMPO-oxidized cellulose nanofibrils...