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Glassy chalcogenides AVBVI obtained by solidification of high-temperature melts inherit the polymolecular nature of the melt. The influence of this circumstance on the optical properties of glasses is important for the fabrication of optical fibers and has not been adequately studied. Bulk samples of high-purity As40 –xS60 +x glasses (0 < x < 5) containing less than (1–2) × 10–5 wt % metal and silicon impurities and not more than (0.5–1) × 10–4 wt % carbon, oxygen, and hydrogen compounds were manufactured, and optical fibers were fabricated from these materials. The IR spectra of 12 cm-long bulk samples and optical fibers of up to 15 m length were recorded in the 1000–2000 cm–1 spectral range. The spectra of the bulk samples and the optical fibers showed absorption bands with maxima at 1950, 1805, 1460, and 1320 cm–1, due to the presence of super-stoichiometric amount of sulfur in the glass. The corresponding extinction coefficients were determined. The results of the study indicate that the stoichiometry of As2S3 can be considered as a factor significantly affecting the optical characteristics of glass. [ABSTRACT FROM AUTHOR]

This paper discusses correlations in the impurity composition of the purest solid group 13-16 elemental substances so far, exemplified by a set of samples in the Exhibition-Collection of Extrapure Substances, a permanent exhibition. The abundance of particular elemental impurities in the samples of the high-purity substances has been determined. Dividing the entire set of impurities into classes, we have accurately determined integral characteristics (average and total concentrations) of impurities in the samples and evaluated the contribution of each impurity class to the total impurity concentration. [ABSTRACT FROM AUTHOR]

The impurity composition of SiH, SiH, and SiH silanes and GeH, GeH, GeH, and GeH germanes isotopically enriched to above 99.9 at % has been studied by gas chromatography/mass spectrometry using capillary adsorption columns. Impurities have been identified by comparing their mass spectra with NIST data and information available in the literature, and by inferring their structure from fragment ions and retention times. We have identified 53 impurity substances in silanes and 42 in germanes: permanent gases; saturated, unsaturated, halogen-containing, and aromatic C-C hydrocarbons; their homologues; alkyl derivatives of silane and germane; chlorogermane; siloxanes; fluorosiloxanes; sulfur compounds; and dioxane. The silicon- and germanium-containing impurities have been shown to be isotopically enriched, as the major component. The detection limits of the impurities are 5 × 10 to 3 × 10 vol %, comparing well with the best results in the literature. [ABSTRACT FROM AUTHOR]

A new technique in which the entire set of impurities in a substance is represented as a set of impurity classes has been developed for estimating the most likely and total concentrations of elemental impurities in samples of high-purity substances. Estimates of the purity of samples with the use of this technique have lower random and systematic errors in comparison with estimates without impurity classification. It has been shown that estimates of the integral characteristics of individual impurity classes in the total set of samples allow one to find the expectation of the total concentration for impurity classes which are represented in particular samples only by detection limits. The results are illustrated by the example of the rare-earth oxide samples in the Exhibition-Collection of Extrapure Substances. [ABSTRACT FROM AUTHOR]

Molybdate-tellurite glasses have been prepared from precipitates obtained by adding aqueous ammonia to hydrochloric acid solutions of tellurium(IV) and molybdenum(VI) compounds. The impurity compositions of the precipitates and glasses have been determined by atomic emission spectroscopy. The results indicate that contamination with metal impurities occurs mainly in the precipitate washing step. Prolonged holding of a glass-forming melt in a porcelain crucible leads to contamination of the glass with aluminum, magnesium, and calcium. [ABSTRACT FROM AUTHOR]

The behavior of macrocomponents and impurities during vacuum distillation of glass melts in the As-Se system with arsenic concentrations of 30 and 40 at % in closed and open systems has been investigated. The possibility of using vacuum distillation in an open system for purifying arsenic selenide glass melts from oxygen and hydrogen impurities has been demonstrated. [ABSTRACT FROM AUTHOR]

This paper examines the impurity composition of the high-purity oxides in the Exhibition-Collection of Extrapure Substances. Data are presented on the overall purity of the oxides and the concentration of different types of impurities. [ABSTRACT FROM AUTHOR]

We have studied the behavior of barium impurities in the form of BaF2 and BaO during vacuum distillation of selenium. The effective Ba partition coefficient is shown to depend on the impurity concentration and evaporation rate. At initial barium contents in the range 3 × 10−3 to 2 × 10−5 wt %, the effective Ba partition coefficient is 600 and 1.5 at distillation rates of 4.7 × 10−6 and 1.5 × 10−3 cm3/(cm2 s), respectively. The chemical form of barium has no significant effect on its partition coefficient. Using a Rayleigh distillation equation, we have determined the equilibrium partition coefficient and the thickness of the diffusion boundary layer in the system. [ABSTRACT FROM AUTHOR]

We describe a procedure for the preparation of As-S-Se and As-Se-Te glasses with low contents of gas-forming impurities (hydrogen, oxygen, and carbon) via melting of extrapure-grade elements in an evacuated silica ampule and purification of the melt by chemical distillation. The impurity concentrations in the glasses thus prepared have been reduced to the following levels: hydrogen, <0.02; oxygen, 0.2; carbon, <0.02; silicon, <0.4 ppm by weight. Using the double-crucible method, we have fabricated glass fibers with various ratios of the core and cladding diameters (1: 25 to 9: 10), protected with a tetrafluoroethylene/1,1-difluoroethylene copolymer coating, which have an average bending strength of 0.5–1 GPa. The minimal optical losses are 150 dB/km at 6.6 μm in multimode As-Se-Te glass fibers and 60 dB/km at 4.8 μm in As-S-Se glass fibers. The effect of microinhomogeneities in the melt on the optical performance of arsenic sulfoselenide glass fibers fabricated by the double-crucible method is examined. [ABSTRACT FROM AUTHOR]