NOPR Collection:

Structure dielectric and AC conduction properties of thermally evaporated Se₃₀Te₇₀ thin films

2016-07-20T06:31:27Z

Title: Structure dielectric and AC conduction properties of thermally evaporated Se₃₀Te₇₀ thin films Authors: Balasbramaniama, T; Narayandass, Sa K; Mangalaraj, D Abstract: Thin films of Se₃₀Te₇₀ are prepared by thermal evaporation onto well cleaned glass substrates at 2.7 mPa. The thicknesses of the films are measured by the Tolansky technique (Fizeau fringes) and are 81 and 138 nm respectively. The X-ray diffractogram shows that the as - deposited films are polycrystalline in nature. Annealing is found to improve the dielectric properties. The capacitance (C) and loss factor (tan δ) are measured from 303-443K in the frequency range 1 kHz-1 MHz. Capacitance decreases with increasing film thickness and applied frequency, while it increases with increase of temperature. The loss factor which shows a pronounced minimum with frequency, increases with the rise of temperature and (tan δ)_minshifts to a higher frequency. The large values of capacitance and dielectric constant (ϵ’) in the low frequency region indicate the possibility of an interfacial polarization mechanism. The dielectric relaxation phenomenon in these films is explained on the basis of dipolar reorientation. The activation energy calculated from the relaxation process is 0.094 and 0.23 eV at low and higher temperatures respectively. The frequency dependence of conductivity and the low value of the activation energy suggest that the conduction mechanism is due to electronic hopping. Page(s): 287-292

Characterization of directly and indirectly oxidized thin indium films

2016-07-20T06:31:14Z

Title: Characterization of directly and indirectly oxidized thin indium films Authors: Gopchandran, KG; Joseph, Benny; Abraham, Johny T; Koshy, Peter; Vaidyan, V K Abstract: The structure and morphology of In₂O₃ films prepared by direct and indirect oxidation mechanisms are reported. XRD studies of In₂O₃ films prepared by annealing of vacuum deposited indium films have shown a <111> texture while the texture of reactively deposited (directly oxidized) films has been found sensitive to deposition conditions. SEM observations show porosity in films obtained by annealing and smooth polycrystalline nature for reactively deposited films. Electrical and optical properties of directly oxidized films are found to be superior to those of indirectly heated films. Page(s): 282-286

Physico-chemical characteristics of fly ash samples from thermal power plants of Orissa

2016-07-20T06:30:46Z

Title: Physico-chemical characteristics of fly ash samples from thermal power plants of Orissa Authors: Mohapatra, R; Kanungo, S B Abstract: Some physico-chemical characteristics of three fly ash samples have been studied with an objective to create a data base for different fly ash samples in the country. It has been observed that relevant physical properties of the samples show systematic variation with particle size distribution. Thus, while apparent density and optical or geometrical area increase with fineness of the particles from sample 1 to 3, true density, voidage and void volume exhibit opposite behaviour. Batch leaching studies indicate that whereas for samples 1 and 2 most of the trace metals (except Cu) leach out rapidly from the surface of the ash particles in the pH range 6.4-7.5, under acidic conditions (pH ~ 4.5) the rates of leaching of most trace metals, except Co and Cd, are relatively slow for sample 3. The pH values of zero charge of the three major oxide constituents namely, SiO₂, Fe₂O₃ and Al₂O₃ as determined by the solid addition method, conform more or less to the literature values of 2.5, 7.0 and 9.5 respectively. Viscosity a measurement of aqueous suspension indicates that sample 3 is least hydrated in water and therefore shows low viscosity value even at high concentration of slurry. Page(s): 271-281

Carbon fibre/epoxy composites: Effect of epoxy network and surface treatment of fibres on interfacial shear strength

2016-07-20T06:30:01Z

Title: Carbon fibre/epoxy composites: Effect of epoxy network and surface treatment of fibres on interfacial shear strength Authors: Varma, D S; Saxena, Sneh; Gupta, Neeraj; Varma, I K Abstract: The paper deals with studies on interfacial shear strength (τ) of carbon fibre composite using single fibre fracture test. Surface modification of desized carbon fibres has been done by argon or oxygen plasma. The effect of network structure on τ has been studied by using difunctional or multifunctional epoxy resins. Interfacial shear strength depends on (i) chemical structure of the epoxy resin (ii) nature of.gas used in plasma generation and (iii) duration of plasma treatment. An increase in cross-link density resulted in a decrease in τ, thereby indicating that a more flexible interface is superior for better adhesion with fibres. Oxygen plasma treated carbon fibres gave highest values of τ. Page(s): 266-270

NOPR Collection:

Structure dielectric and AC conduction properties of thermally evaporated Se30Te70 thin films

Characterization of directly and indirectly oxidized thin indium films

Physico-chemical characteristics of fly ash samples from thermal power plants of Orissa

Carbon fibre/epoxy composites: Effect of epoxy network and surface treatment of fibres on interfacial shear strength

Structure dielectric and AC conduction properties of thermally evaporated Se₃₀Te₇₀ thin films