• S H Pawar

      Articles written in Bulletin of Materials Science

    • Crystal growth and electrical properties of CaSO4:Dy single crystals

      S H Jagdale S H Pawar

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      Single crystals of CaSO4:Dy, with and without charge compensator were grown by the solution growth technique. Electrical conductivity was studied at room temperature for diverse concentrations of Dysprosium and showed that it increases upto 0.2 wt % of Dy, beyond which saturation sets in. Electrical conductivity was studied in the region 400 to 700°K and the migration energies estimated for various dopant concentrations. The variation of electrical conductivity and migration energy with diverse dopent concentration is explained on the basis of the theory of defects. The thermoelectric power measurements reveal that the crystals grown are ofP type.

    • Effect of zinc composition on properties on PEC cells based on sprayed Cd1−xZnxS films

      M D Uplane S H Pawar

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      Polycrystalline Cd1−xZnxS films were prepared by spray pyrolysis technique, both on conducting and non-conducting glasses. These films were used as photoanodes in photoelectrochemical cells. The optical and electrical properties of these cells are studied and the effect of zinc composition on these properties is revealed.

    • Studies on dynamicI-V curves of semiconductor-liquid junction cells formed with Cd0·8Zn0·2S films prepared at various spray rates

      M D Uplane S H Pawar

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      Cd0·8Zn0·2S films were prepared by the spray pyrolysis technique on glass and conducting glass (fluorine doped tin oxide) substrates, by spraying aqueous solutions of cadmium chloride, zinc chloride and thiourea. The spray rate was varied from 4 cc/min to 16 cc/min. It is found that film thickness increases with increase in spray rate. The electrical and optical properties of the films namely dark conductivity, thermoelectric power and optical absorption were studied; conductivity and thermoelectric power are higher for the films prepared at lower spray rate (4·3 cc/min).

    • Thickness dependent properties of electro-chemical-photovoltaic (ecpv) cells formed with chemically deposited CdS films

      S H Pawar L P Deshmukh

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      Thin polycrystalline cadmium sulphide photoelectrodes of various thicknesses have been deposited on polished stainless steel substrates by a chemical bath deposition technique. The electrochemical photovoltaic (ecpv) cells were formed with these photoanodes. Short circuit current (Isc) and open circuit voltage (Voc) are recorded under 100 mW/cm2 light intensity. It is found thatIsc increases with increase in thickness of the photoanode whereasVoc remains more or less constant. The other cell parameters, maximum power output (Pm) and efficiency (η) are found to improve with increasing thickness, while fill factor (f.f.) varies slightly with the photoanode thickness. The semiconductor-liquid space charge region capacitances in the dark were measured. The variation of 1/C2 versus applied reverse biasV is nonlinear. The deviation from straight line behaviour is attributed to the existence of surface states and degeneracy of states. The flat band potential is determined from the extrapolation of the (1/C2) −V plot to the voltage axis, and is found to vary with the thickness of the photoanode.

    • Electrochemical bath deposition technique: Deposition of CdS thin films

      S H Pawar C H Bhosale L P Deshmukh

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      Cadmium sulphide thin films have been deposited onto chromium plated stainless steel substrates under the influence of electric field. The various deposition parameters such as speed of rotation of the substrates, temperature of the chemical bath, molar concentrations of solution and the strength of the electric field were kept at optimized conditions. The electrochemical photovoltaic (ecpv) cells are formed with CdS film electrodes. The properties of CdS films andecpv cells are monitored with selective values of the electric field employed in the controlled precipitation technique. This relatively new technique is described and the possible film formation mechanism suggested.

    • Spray pyrolytic deposition of CuBiS2 thin films

      S H Pawar A J Pawar P N Bhosale

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      Thin films of CuBiS2 have been deposited on glass substrates using spray pyrolysis technique. The effect of substrate temperature on the growth of CuBiS2 thin films is studied in the range of 150 to 400°C. The best quality films are grown at substrate temperature 250°C with 0·1 M composition. Other preparative parameters like spray rate, pressure, height of the solution, etc are optimized with respect to substrate temperature. Some optical and electrical properties of CuBiS2 films are also studied and reported.

    • Preparation and properties of Bi2−xAsxS3 thin films by solution-gas interface technique

      S H Pawar P N Bhosale

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      The solution gas interface technique by which thin films of Bi2−xAsxS3 were deposited is described in this paper. The semiconducting properties of the interface grown Bi2−xAsxS3 thin films are studied. The optical absorption, dark resistivity and thermoelectric power of the films were studied and results are reported.

    • Foreword

      C N R Rao S H Pawar

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    • Studies on K-Sb-S films deposited at different substrate temperatures and their photoelectrochemical behaviour

      C H Bhosale C D Lokhande S H Pawar

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      The electrical and optical properties of thin films of K-Sb-S prepared by spraying a solution of antimony potassium tartrate and thiourea onto heated conducting and non-conducting glass substrates are described. The polycrystalline films produced at an optimum spray rate and at different substrate temperatures were characterized for semiquantitative analysis. The films show variation in thickness with substrate temperature. Photoelectrochemical cells formed with the K-Sb-S film electrode, 0·5 M ferrocene in dimethylsulphoxide as the electrolyte and carbon as the counterelectrode were studied for their current voltage characteristics in dark and in light. Variation of short circuit current and open circuit voltage with light excitation intensity is also described.

    • Studies on iron-chromium redox storage system

      S H Pawar R D Madhale P S Patil C D Lokhande

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      The performance of the redox storage battery based on the Fe-Cr redox couple is studied in charging and discharging modes of the system. The stability of each charged species is determined by measuring the variation of half-cell potential with time. The spectra of the electrolytes are recorded before and after charging of the system. The effect of atmosphere on the charged species has also been investigated.

    • Electrochemical synthesis of Tl-based highTc single-phase superconductor thin films

      L A Ekal N V Desai S H Pawar

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      Co-deposition of the Tl-based superconductors using electrodeposition technique was successfully carried out. Different processing parameters such as deposition potential, current density, deposition period etc were studied. The Tl-based alloyed thin films were deposited at a constant potential of −1·25V with respect to SCE electrode onto silver substrates and oxidized at 850°C in oxygen atmosphere. The samples thus prepared showed superconducting behaviour below 122·5 K and the critical current density was 1·5×103A/cm2. Electrochemical synthesis of Tl-based highTc single-phase superconductor thin films is also reported.

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