V. G. Pimenov

Effect of Oxygen Impurity on the Optical Transmission of As2Se3.4Glass

As2Se3.4glass samples with controlled oxygen content in the range (1.4–7.9) × 10–2wt % were used to assess the effect of oxygen impurity on the IR absorption spectrum of the glass. The spectral dependence of the extinction coefficient for oxygen impurity was determined in the range 600–1400 cm–1. It was shown that the presence of 10–5wt % O gives rise to additional losses comparable to the intrinsic losses in the CO2lasing range.

Low-loss, high-purity (TeO2)0.75(WO3)0.25 glass

By melting a mixture of high-purity oxides in a platinum crucible under flowing purified oxygen, we have prepared (TeO2)0.75(WO3)0.25 glass with a total content of 3d transition metals (Fe, Ni, Co, Cu, Mn, Cr, and V) within 0.4 ppm by weight, a concentration of scattering centers larger than 300 nm in size below 102 cm−3, and an absorption coefficient for OH groups (λ ∼ 3 μm) of 0.008 cm−1. The absorption loss in the glass has been determined to be 115 dB/km at λ = 1.06 μm, 86 dB/km at λ = 1.56 μm, and 100 dB/km at λ = 1.97 μm. From reported specific absorptions of impurities in fluorozirconate glasses and the impurity composition of the glass studied here, the absorption loss at λ ∼ 2 μm has been estimated at ≤100 dB/km. The glass has been drawn into a glass-polymer fiber, and the optical loss spectrum of the fiber has been measured.

Preparation of high-purity TeO2-ZnO glass batches

Tellurium oxide-zinc oxide glass batches have been prepared through chemical vapor deposition from tellurium and zinc alkyl compounds in an oxyhydrogen flame onto the lateral surface of rotating cylindrical substrates. The composition of the deposits has been shown to be determined by the relative amounts of the metalorganic precursors in the gas phase. Varying the deposition conditions, we obtained both amorphous and crystalline deposits, with concentrations of metallic impurities below 1 ppmw. Melting the deposits, we prepared high-purity (TeO2)1 − x(ZnO)x (0.15 ≤ x ≤ 0.35) glasses.

Removal of barium impurities from selenium by vacuum distillation

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.

High-Purity As2S1.5Se1.5 Glass Optical Fibers

Core–clad optical fibers were fabricated from high-purity As2S1.5Se1.5 glass, and their properties were studied. The arsenic sulfo-selenide was prepared by melting a mixture of high-purity arsenic monosulfide, arsenic, and selenium. Optical fibers with core/clad diameters of 300/400 and 200/400 μm were fabricated by the double-crucible method. The minimum loss was found to be 60 ± 20 dB/km at 4.8 μm and 200–300 dB/km between 4 and 6 μm. The numerical aperture of the fibers was 0.28. A 1.5-m-long section of the fiber transmitted 6-W CO laser radiation. The average bending strength of the 400-μm-diameter fibers was 0.8 GPa.

Determination of impurities in aluminum isopropoxide by inductively coupled plasma atomic emission spectrometry

A procedure has been developed for the determination of impurities in aluminum isopropoxide by inductively coupled plasma atomic emission spectrometry. The matrix effect has been compensated by adding a Bi internal standard. The detection limits of impurities are 10−7 to 10−5 wt %.

Fine purification of monoisotopic 32S and 34S

We have proposed and tested a combined process for ultrapurification of monoisotopic 32S and 34S sulfur, which comprises thermochemical treatment of sulfur vapor on silica and ceria packing, melting with aluminum, and distillation. The impurity composition of the purified sulfur has been determined by atomic emission and IR spectroscopy. We have obtained monoisotopic 32S and 34S sulfur samples comparable in chemical purity to high-purity sulfur of natural isotopic composition.

Assessment of interlaboratory and between-method discrepancies in composition certification of high-purity solid elemental substances and nanomaterials

We have assessed interlaboratory and between-method discrepancies in the certification of standards of high-purity nanomaterials and precursors and analyzed the dependence of the discrepancy on the impurity concentration (an important factor, influencing the discrepancy value) and analytical method.

Determination of impurities in TeO2-WO3 fiber-optic glasses by chemical atomic emission spectrometry

We describe a procedure for arc source chemical atomic emission analysis of high-purity TeO2-WO3 tellurite glasses using preconcentration of nonvolatile impurities via reactive vaporization of the major glass constituents by fluorination with xenon difluoride in an autoclave. The detection limits of impurities are 10−8 to 10−6 wt %.

Impurity composition of molybdate-tellurite glasses prepared from mixtures precipitated from hydrochloric acid solutions of tellurium and molybdenum compounds by ammonia

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.