Arsenic-sulfur Glasses Research Articles

Mechanism of the dissolution of As–S chalcogenide glass in n-butylamine and its influence on the structure of spin coated layers

Chalcogenide glass thin layers are useful to many practical applications especially for the fabrication of infrared (IR) optical elements. In comparison to the conventional vacuum deposition methods of their preparation, recently chemical methods such as spin coating are gaining attention. They involve dissolution of the source bulk glass in appropriate solvent and then depositing its thin layer. Chemical processes occurring during the glass dissolution and thin layer deposition determine the physico-chemical properties of deposited thin layers. The structure of chalcogenide bulk glasses (AsxS100−x, where 30≤×≤40) and their solutions in n-butylamine have been studied in this work by Raman spectroscopy. From the composition and time dependence of Raman spectra of solutions the mechanism of arsenic–sulfur glass dissolution involving the reaction of aliphatic amine solvent with homopolar SS bonds is proposed and the presence of alkyl ammonium arsenic sulfide salts in thin layers is established.

The mechanism of hologram formation in arsenic-sulfur glass

Abstract Glass of composition 7 mole % As, 93 mole % S was examined using calorimetry, chemical extraction and electron spin resonance in order to determine the mechanism whereby phase holograms are formed in this material. We have determined that, after hologram formation, the material consists of a glassy matrix with microcrystals of almost pure α sulfur. The same process (precipitation of α microcrystals) can be induced thermally in these glasses, but the photo-induced change is markedly faster.

The mechanism of hologram formation in arsenic-sulfur glass

Glass of composition 7 mole % As, 93 mole % S was examined using calorimetry, chemical extraction and electron spin resonance in order to determine the mechanism whereby phase holograms are formed in this material. We have determined that, after hologram formation, the material consists of a glassy matrix with microcrystals of almost pure α sulfur. The same process (precipitation of α microcrystals) can be induced thermally in these glasses, but the photo-induced change is markedly faster.

Optically Formed Dielectric Gratings in Thick Films of Arsenic–Sulfur Glass

Optically Formed Dielectric Gratings in Thick Films of Arsenic–Sulfur Glass

Thermal Expansion of Arsenic-Sulfur Glasses

The thermal expansion of the As-S glasses has been measured and the softening temperature (At), transformation temperature (Tg), and linear coefficients of thermal expansion from room temperature to Tg and Tg to At (α1 and αh, respectively) were determined from the expansion curve. The relationships of composition and At, Tg or α1 are interpreted by the structural model proposed for the As-S glasses previously.

Thermal Expansion and Its Related Properties of Arsenic-Sulfur Glasses

Thermal Expansion and Its Related Properties of Arsenic-Sulfur Glasses

On the Infrared Absorption Spectra of As-S Glasses

Arsenic trisulfide glass is of interest as a material of higher refractive index, transparent in the infra-red and having low melting characteristics.The structure of arsenic trisulfide glass has been studied by X-ray diffraction technique, and the data indicate a short range order arrangements of the atoms similar to those in the crystalline orpiment structure. However, there have been very few reports of structure determinations of sulfide glasses which have higher content of sulfur than that of As2S3. In undertaking to provide the necessary structural information, the infra-red absorption of samples with vorious compositions was examined.As2S3, one of raw materials, is synthesized by passing purified H2S gas into 6N-HCl solution of purified As2O3, and dried at temperatures below 100°C, but it was very difficult to remove the small content of Cl- included in As2S3. This crude As2S3 formed black-red glasses. To obtain blight red glasses, As2S3 must be purified by vacuum distillation.In oftaining the glass, at first, the raw materials were mixed up and melted one hour at 360°C by using porcelain crucible, but in this case it was found by infra-red absorption method that the glass contains some oxygen impurities (Fig. 2, Table. 3). Therefore, the method of preparation of the glass samples was changed in the following way.Sufficiently pure elements that exactly weighted for yielding 5-30 grammes of glass were stored in the thick-walled pyrex-type glass ampoules, which were then evacuated and sealed while still under vacuum. The ampoules were heated up to 600°C or 450°C in a furnace, and then quenched or allowed to cool down to room temperature. Infra-red absorption measurements between 1000-400cm-1 were made through polished parralle-sided discs, approximately 0.2-2 millimeters thick, or through very thin film sandwitched by KBr plates, using a Hitachi-Perkin Elmer Model 125 and/or Japan Spectroscopic DS-402 Grating Infrared Spectrometer or Hitachi Infracord.The results obtained were shown in the Table. 4 anb 5.Kolomites an Pavlov suggested that the absorption band appeared at around 800cm-1 is due to As2Se3. To ascertain their suggestions, the As-S glass samples contained Se (No. 7) were prepared, yet it resulted in no indication of absorption band at around 800cm-1. According to the study by Tanaka et al. on arsenic-sulfur glasses prepared by evaporation under normal pressure, it was suggested that the absorption band appered at around 800cm-1 is attributed to the vibration of As=S bond in the As2S5 glass, while the absorption band at around 790cm-1 is due to the inclusion of arsenic disulfide (As2S2 or As4S4) component dissolved in the As2S3 glass. For the experiments of Kolomiets, the use of pure elements did not bring in the absorption band at around 800cm-1 (from Glass No. 73-83). On the contrary, when unpurified elements were used or arsenic oxide was added to As-S glass, the absorption bands at around 800cm-1 (in the case of high content of S) and around 790cm-1 (in the case of low content of S) appeared. And the absorption band shifted gradually from 790cm-1 to 800cm-1 with increasing S content (as indicated in Table. 4). When arsenic oxide was added to As-S glass, SO2 gas produced by chemical reaction between As2O3 and S was ascertained by the appearance of special infra-red absorption bands (1330cm-1 and 1150cm-1) and by the gas chromatographic analysis. On

Infrared Absorption Band near 12.51 µ of Arsenic-Sulfur Glasses

Infrared Absorption Band near 12.51 µ of Arsenic-Sulfur Glasses

Relationship of Composition and Density of Arsenic-Sulfur Glasses

Relationship of Composition and Density of Arsenic-Sulfur Glasses

Fiber Optics XI Performance in the Infrared Region*†

With the advent of infrared fiber-optics components which are capable of transmission over the wavelength range 1 to 12 μ, there is a need for reliable techniques for evaluating their performance at these wavelengths. The optical properties, i.e., spectral transmittance, radiation characteristics, and image quality, of cylindrical and conical fibers are presented. An evaluation approach is evolved, based on the radiation pattern and spectral transmission profile measurements, and the concept of “characteristic curves” is introduced. Results of measurements on oxide-glass fibers (0.4–5 μ) and arsenic sulfur glass fibers (1–12 μ) are presented.

Direct Formation in Sheet Form of Arsenic-Sulfur Glasses by Distillation under Normal Pressure

An apparatus of a laboratory scale was constructed for the direct formation in sheet form of arsenic-sulfur glasses by the distillation of raw glass batches under normal pressure. The present apparatus comprises a vertical distillation chamber, a batch container kept in the chamber, and a condensate depositer attached at the bottom of the chamber. The following materials are easily available for making the distillation chamber, batch container and condensate depositer: silica glass, 96% silica glass and glazed porcelain. Aluminum metal is especially recommended as a material of the condensate depositer with good temperature uniformity. By modifying the inner shape of the condensate depositer, arsenic-sulfur glasses can be directly formed in shapes of disk, square plate, circular and square rods, wedge, hemisphere, prism, and so on.The optimum temperature condition of operating the above apparatus for the direct formation of transparent arsenic-sulfur glasses was as follows: 470°-550°C. for the temperature of batch container; 330°-430°C. for that of condensate depositer. The X-ray diffraction measurements on transparent sheets condensed under the above optimum temperature condition of distillation and on their crushed. powders showed that these sheets were glassy.When the batch container of about 30ml. capacity and about 45mm. diameter was used, it usually took 3-6 hours after starting to heat the container to condense a glass disk of about 40mm. diameter and 3-4mm. thickness under the above temperature condition of distillation. It was desirable for the condensation of a glass disk with larger diameter and thickness than the above to increase the capacity of the batch container; one of the effective methods for increasing the rate of the glass condensation was to increase the diameter of the batch container.The composition of condensed glasses was usually within the range of about 61 weight % As (As2S3.0) to about 65 weight % As (As2S2.5) when the composition of raw glass batches was As2S3 and/or As2S3+S(mole ratio). The arsenic content of condensed glasses was decreased with decreasing the arsenic content of raw glass batches, and the composition of the glasses was usually within the range of about 34 weight % As (As2S9.0) to about 54 weight % As (As2S4.0) when the composition of raw glass batches was As2S3+8S(mole ratio). The arsenic content of condensed glasses was decreased with lowering the temperatures of the batch container and/or the condensate depositer when the composition of raw glass batches was kept constant.Mixtures of arsenic and sulfur in the powder forms were also available as raw glass batches for the direct formation of arsenic-sulfur glasses; the temperature of operation in this case was nearly equal to the above case using raw glass batches of the arsenic trisulfidesulfur system.

Infrared Absorption Spectra of Arsenic-Sulfur Glasses Prepared by Evaporation under Normal Pressure

The infrared absorption spectra in the range of the wave length from 2 to 25μ have been investigated on arsenic-sulfur glasses, including plastic sulfur, directly prepared in the film form by the evaporation under normal pressure using the evaporation outfit and operating condition shown in the previous paper (Reference 6). Each of the arsenic-sulfur glasses itvestigated here was allowed to cool in atmospheric gas after the condensation in the molten state on the back-surface of aluminum target for rather short time (5-20 min), and was separated from the target by the chemical procedure using dilute hydrochloric acid. The spectra recorded for the above arsenic-sulfur glasses of the composition ranging from As2S2.8 to As2S15.4 were 9.58±0.05μ(1044±6cm-1) accompanied by the absorption band at 12.67±0.02μ(789±2cm-1), 9.55±0.05μ(1047±6cm-1) appeared without the absorption band at 12.67±0.02μ(789±2cm-1), 11.95±0.15μ(837±11cm-1), 12.51±0.05μ(799±4cm-1), 12.67±0.02μ(789±2cm-1), 14.84±0.11μ(674±5cm-1), 15.18±0.05μ(659±3cm-1) appeared together with the absorption band at 20.69±0.08μ(483±2cm-1), 19.93±0.07μ(502±2cm-1), 20.69±0.08μ(483±2cm-1), 21.09±0.10μ(474±3cm-1) and 21.36±0.10μ(468±2cm-1). The spectra for the plastic sulfur were 7.66±0.03μ(1305±6cm-1)(w), 10.71±0.05μ(934±5cm-1)(vw), 11.04±0.03μ(906±3cm-1)(vw), 11.43±0.03μ(875±2cm-1)(vw), 11.95±0.15μ(837±11cm-1)(s), 14.06±0.03μ(711±2cm-1)(w), 14.65±0.05μ(683±3cm-1)(vw), 15.20±0.05μ(658±3cm-1)(w) appeared without the absorption band at 20.69±0.08μ(483±2cm-1), 19.50±0.20μ(513±6cm-1)(vw) and 21.36±0.10μ(468±2cm-1)(s), where s, m, w and vw denoted strong, medium, weak and very weak bands, respectively.No absorption bands due to dissolved gases have appeared for arsenic-sulfur glass films used in the present investigation. Contrary to the observation by Kolomiets and Pavlov (Reference 4) that the absorption band at around 12.5μ was not appeared for “As2S3 and As2S3⋅As2Se3 glasses” but for “As2S3⋅2As2Se3 and As2Se3 glasses” which were all synthesized according to the procedure by Goryunova, Kolomiets and Shilo (Reference 10), the absorption bands at around 12.67μ(789cm-1)(s) and around 12.51μ(799cm-1)(m) have been respectively recorded for glasses of the compositions near As2S2.8 and As2S8.6 which were both prepared from the nearly selenium-free batches by the present evaporation and condensation method.A satisfactory assignment of the absorption bands recorded for the above glasses of the arsenic-sulfur system has been made mainly from the relationship among glass compositions and band characteristics (the position, broadness, sharpness and intensity of band) and from the comparison of band characteristics among glasses and plastic and crystalline sulfurs, as follows: (1) the absorption band appeared at around 12.51μ(799cm-1) is attributed to the vibration of As=S bond (the As-S bond with an increased double bond character) in the As2S5 glass

Direct Deposition in Film Form of Arsenic-Sulfur Glasses by Evaporation under Normal Pressure

Arsenic-sulfur glasses can be directly prepared in the film form by thermal evaporation under normal pressure employing an evaporation outfit devised so as to prevent oxidation by atmospheric gas. The prevention of oxidation is made by contacting a plane target of a moderate thickness with the top edge of batch container. The moderate thickness of target is in the neighborhood of 0.05mm when the target material is aluminum.The preparation of transparent glass films requires control of the target temperature. In general, during an evaporation the batch has been heated up to 120°-150°C higher than the target temperature. In the case of As2S3 batch, target temperatures below about 345°C have been resulted in opaque and/or crystalline films whereas at temperatures of 345°-365°C transparent glass films of good quality have been obtained. Target temperatures above about 365°C, however, cause the formation of bubbles in the film. Transparent glass films can be successively obtained by replacing the target during the continuous evaporation. The optimum temperature of target is shifted toward the lowered temperature and at the same time the optimum temperature range is widened with the increase in the sulfur content of batches. In the case of the batch of As2S3+11S in mole ratio, the optimum range of target temperature has been 250°-290°C. The direct preparation of transparent glass films from the batch mixture of arsenic and sulfur can be made by the almost the same temperature control of target as in the case of the batch of As2S3-S system. The rate of deposition of the glass films has been about 0.01mm/min. when the difference in temperature was 120°-150°C between target and batch. When the material of target is aluminum, the dissolution of the target in dilute hydrochloric acid is one of the convenient ways of separating the glass film from the target. In this way, transparent glass films of 0.05-0.3mm thickness have been successfully obtained without special care.The arsenic content of transparent glass films obtained is increased with that of batches, and is increased with raising the target temperature within the optimum range. The arsenic content of the glass films is increased to some extent by the continuous evaporation and successive depositions of the film on new targets. The composition of the films obtained from As2S3 batch has been in the range of about 59 weight% arsenic (As2S3.2) to about 63 weight% arsenic (As2S2.7), and the compostion of the films from As2S3+11S batch in the range of about 23 weight% arsenic (As2S16) to about 37 weight% arsenic (As2S8). In this paper, the arsenic-sulfur mole ratios are expressed in the form of formulas for each glass film.The X-ray diffraction measurements on the transparent films of the compositions near to As2S3 and As2S8 and on the ircrushed powders show that these films are glassy. A few additional properties observed from glass films of the composition ranging from As2S2.7 to As2S8.2 are as follows: Infrared transparent up to about 12μ (transmission=about 70%); no appearance of devitrification after the heat treatment in moist air at about 95°C for 9 hours and/or after the exposure to moist air at room temperature for 1 year; inert to both hot water and 10 weight% hydrochloric acid at about 95°C (weight loss after 9 hours=10-4-10-5g/100g of reagent); high electric resistivity (volume resistivity at room temperature=1015-1016 ohm-cm).