Measurement of High Temperature Thermodynamic Propertiesof Several Binary Alkali Silicate Glasses

The method for continuous measurement of the high temperature heat content, developed by W.Oelsen et al. and applied to the glasses by M.Tashiro, was examined and modified in some points. Relations between the temperature and heat contents referred to the standard temperature 25℃, were determined for the some glasses of R(2)O-SiO(2) system, and the specific heats as well as the entropies were calculated. Comparing the results, some views have been obtained relating to the effect of the species and content of alkali ions on the thermodynamic quantities of such glasses

Diffusion Phenomena of Silver Ion in Molten Sodium Borate by Chronopotentiometry

Diffusion phenomena of silver ion in the molten sodium diborate of low silver ion content were investigated at the temperature range from 880℃ to 625℃ by means of chronopotentiometry. From the results, it was shown that the silver ion was reduced reversibly to metallic state at the silver electrode used and silver ion was transported only by diffusion in case that transition time in a potential-time relation was within several seconds. Diffusion coefficients measured at various temperatures satisfied Arrhenius equation. The activation energy of diffusion and diffusion coefficient were respectively 32Kcal/mol and 6.5×10(-7) cm(2)/sec at the liquidous temperature. By comparing these values with those obtained in some molten salts, the difference of structure between the molten glass and molten salts was discussed. Moreover, the consideration for the size of borate anion existing in the molten glass was also tried from the viewpoint of rate process and from Stokes-Einstein's equation

Consideration for the correlation between basicity of oxide glasses and chemical shift of O1s binding energy in XPS

Binding energy of O1s core electron measured in XPS is a candidate to determine new scale of Lewis basicity of oxide ion in glass. Some mathematical expressions for the basicity or XPS chemical shift, such as charge parameter and optical basicity, are compared with experimental O1s binding energy in binary alkali oxide glasses. The expressions so far in use need some modification in parameters. A new empirical expression introduced in this paper gives new concept and universal scale of basicity

Chemical States of Fluorine Atoms and Laser-Induced Crystallization in rf-Sputtered Thin Films of Amorphous Lead Fluorosilicate

Amorphous films of lead oxyfluorosilicate were prepared with a rf-sputtering technique, and the distribution profiles of the component elements and chemical states of the fluoride ions were analyzed with an X-ray photoelectron spectrometer. Si atoms with an expanded coordination, O(4)Si-F, were present near the surface, and O(3)Si-F units were present in the deeper part of the films. Electrical resistance indicated transition to a conduction state for the films containing fluoride ions, while the films were crystallized to precipitate low quartz by the irradiation of He-Ne laser of 3 mW up to 1 sec

Preparation and Characterization of Ti(2)O(3) Films Deposited on Sapphire Substrate by Activated Reactive Evaporation Method

(001)-oriented Ti(2)O(3) films were epitaxially grown on a(001)-face of sapphire single-crystalline substrate by an activated reactive evaporation method. The formation ranges of stoichiometric and nonstoichiometric Ti(2)O(3) films were determined as a function of the substrate temperature (Ts), the oxygen pressure (Po(2)) and the deposition rate. Stoichiometric Ti(2)O(3) films were grown at Ts≧673K under Po(2)≧1.0×10(-4)Torr, which showed the metal-insulator transition with a sharp change in electrical resistivity from 3.5×10(-2) to 2.6×10(-3)Ωcm at 361K. Nonstoichiometric films prepared under less oxidized conditions did not exhibit the transition. The nonstoichiometry of the Ti(2)O(3)films was discussed in terms of excess Ti ions

Studies on optical properties of SnO-based glasses as lead-free glasses

The preparation of SnO-SiO(2), SnO-B(2)O(3), and SnO-GeO(2) glasses by melting in air was performed. The prepared SnO-GeO(2) glasses were large enough to measure optical properties whereas the vitrification in SnO-SiO(2) and SnO-B(2)O(3) systems was difficult. PbO-GeO(2) and BiO(1.5)-GeO(2) glasses were also prepared for comparison with SnO-GeO(2) glasses. The densities, glass transition temperatures, and optical properties such as refractive indices, dispersion, and transmission spectra of SnO-GeO(2), PbO-GeO(2), and BiO(1.5)-GeO(2) glasses were measured. On the basis of the results, the potential for SnO-GeO(2) glasses as lead-free glasses is particularly discussed from the viewpoint of optical properties

Amorphous Oxides Prepared from Organometallic Compounds Part2. Structure Evolution in Sodium Borosilicate Gels

Sodium borosilicate gels of compositions similar to that of Vycor(R) glass like 80SiO(2).15B(2)O(3).5Na(2)O (wt%) were prepared from hydrolysis and polycondensation of metal alkoxides under the HCl catalysis. Variation of specific surface area and porosity with temperature indicated that closed pores were opened below 400℃, and collapsed above 450℃ after the porosity reached a maximum value around 450℃. The structural evolution was examined due to IR spectra and a phase separation in the gels was observed. The solubility of the gels into 1N-HCl was studied as a function of the treatment temperature

Measurements of Decomposition Voltage of Na(2)O-SiO(2) System at Elevated Temperature by Commutator Technique

Decomposition voltages of Na(2)O (30-50 mole % )-SiO(2) binary system were estimated at the temperature range of 700~1200℃ by commutator technique. As the experimental procedure, relations between electrolytic current and resulting polarization potential without ohmic loss were observed by 20 cps mechanical commutator, using Pt|Na(2)O-SiO(2)|Pt electrochemical system. Experimental decomposition voltages determined from above relationship were the value of 1.5~2.0 V at the temperature beyond about 800℃ with comparatively less reproducibility. Further investigations on the decomposition reaction mechanisms were made in reference to both a series of reversible decomposition voltages derived from thermodynamic calculations on the several proposed decomposition reactions and chemical equilibrium in vitreous silicates

Preparation of ZnO Films by Activated Reactive Evaporation Method

Zinc oxide films were prepared on silica glass substrates by the use of an r.f. activated reactive evaporation (ARE) method, and were examined by X-ray diffraction (XRD) and scanning electron micrograph (SEM). XRD measurements indicate that the films were c-axis oriented and that an r.f. plasma of Zn and O was necessary for the ZnO film deposition. Substrate temperature, oxygen gas pressure, evaporation rate, r.f. power and inlet position of oxygen gas effect the c-axis orientation, the growth rate and the microstructure of the films. Optimum conditions for a dense film with a fine texture of the surface and having good crystallinity were as follows: the substrate temperature;400℃, the evaporation rate;5.0(A)/s, the oxygen pressure;2.0x10(-4) Torr, the r.f. power;150 to 200W, and the oxygen gas inlet near the substrate. For the film prepared under the optimum conditions, the standard deviation　σ　of the rocking curve for the (002) diffraction was 1.9deg, smaller than that of the film prepared by using an r.f. sputtering method

Amorphous Oxides Prepared from Organometallic Compounds Part 1. Preparation of Sodium Borosilicate Gels

Sodium borosilicate gels of compositions similar to that of Vycor(R) glass like 80SiO(2).15B(2)O(3).5Na(2)O(wt%) were prepared from hydrolysis and polycondensation of tetraethyl orthosilicate, trimethyl borate, and sodium methylate under the HCl catalysis. Variation of the gelation time is examined as a function of the mixing ratio of the starting materials and the catalyst. The thermal behavior of the gels has been discussed on the basis of their TG and DTA traces