• P Pramanik

      Articles written in Bulletin of Materials Science

    • Electroless deposition of Alpha-PbO2 and Tl2O3

      R N Bhattacharya P Pramanik

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      A chemical method for electroless deposition of thin film ofa-PbO2 and Tl2O3 has been developed. The deposition has been performed by ammonia, persulfate ion and metal ions at a higher temperature. The electrical resistance, mobility and carrier concentration have been measured with variation of thickness of the films. Optical absorption spectra reveal the band edges which are 1·7 eV and 1·95 eV ofa-PbO2 and Tl2O3 respectively.

    • New chemical methods for the deposition of Cu1·8S and TlSe thin film

      R N Bhattacharya P Pramanik

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      New chemical methods for the deposition of thin film of Cu1·8S and TlSe have been developed. The deposition of Cu1·8S thin film has been performed by thiourea, ammonia and Cu2+ ions at room temperature, while TlSe thin films are obtained from triethanolamine as complexing agent, ammonia, sodium selenosulphate solution and Tl1+ ions at room temperature. The electrical resistance, mobility, carrier concentration and optical band gap have been measured.

    • A novel technique for the preparation of fine ceramic oxides

      Amita Pathak P Pramanik

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      In this paper, we put forward a novel and simple chemical route for the preparation of fine ceramic oxides i.e. ferrites using triethylammonium carbonate as the precipitating agent. The particles were studied and characterized by X-ray diffraction and scanning electron microscopy. The emphasis is on the superiority of this technique over other chemical and conventional routes.

    • A new chemical route for the preparation of fine ferrite powders

      P Pramanik Amita Pathak

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      Precursors to MFe2O4 [spinels ferrites; where M = Ni(II), Co(II) and Zn(II)] have been prepared by the evaporation of polyvinyl alcohol added mixed metal nitratesolution, in presence and absence of urea. Theprecursor materials have low ignition temperature and are spontaneously combustible at low temperatures (250°C to 400°C). The heat liberated through the process is sufficient for the crystallization of the desired ferrite phase. The urea added process resulted in finer, superparamagnetic particles (12–17 nm) compared to the process without urea (particle size 25–30 nm). The ultrafine ferrite powders obtained have been characterized by X-ray powder diffraction (XRD), thermal gravimetry (TG), differential scanning calorimetry (DSC), infrared spectroscopy (IR), transmission electron microscopy (TEM) and room temperature magnetic measurement studies.

    • Synthesis of nano particle of inorganic oxides by polymer matrix

      P Pramanik

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      Ultrafine (⩽ 150 nm) powders of spinels [MFe2O4 where M = Ni(II), Co(II) and Zn(II)]; rare-earth orthoferrites [RFeO3 where R = Sm, Nd and Gd], and rare-earth garnets [R3Fe3O12 where R = Sm, Nd and Gd] with good purity and chemical homogeneity were prepared through two new versatile chemical routes. The first route involved the coprecipitation of the desired metal nitrates from their aqueous solution, in presence of a water soluble polymer-polyvinyl alcohol (PVA), by triethyl ammonium carbonate solution. The other process involved complete evaporation of a mixture of optimum amounts of PVA and the desired aqueous metal nitrate solutions, with and without the addition of optimum amounts of urea when the mixture was evaporated to a pasty mass. In addition, detailed study on the reported potassium ferricyanide route was also carried out for the production of the rare-earth orthoferrite powders. The various precursor as well as the heat-treated mixed-oxide powders, prepared through each of the routes, were compared by the physical characterization studies involving thermal gravimetry and differential scanning calorimetry, infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy, and room temperature magnetic measurements.

    • Chemical synthesis of nanosized oxides

      P Pramanik

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      Fine powder of single and binary mixed oxides can be produced by decomposition of the respective metal nitrates and polyvinyl alcohol (PVA) or, a mixture of PVA and polyacrylic acids. These mixtures, after spray drying, yield a brown fluffy mass, which is spontaneously combustible and the heat liberated is sufficient for the crystallization of the desired oxide phase. The rate of combustion controls the growth of the particles. This can be manifested by combustion of the mixture in controlled atmosphere. The nanoparticles of the oxide system studied are: spinels [MFe2O4 where M = Ni(II), Co(II), Zn(II), Mg(II)]; orthoferrites [MFeO3 where M = Gd(III), Sm(III)]; LaAlO3, NdGaO3, CaO/MgO/Y2O3 stabilized zirconia (ZrO2); lead zirconate titanate (PZT), lanthanum modified lead zirconate titanate (PLZT) and BaTiO3.

    • Synthesis of spodumene and spodumene — zirconia composite powders using aqueous sol-gel method

      N N Ghosh P Pramanik

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      Pure spodumene and spodumene-zirconia (5, 10, 15 mol%) composite powders were prepared using aqueous sol-gel method employing lithium formate, aluminium formate, zirconium formate and tetraethoxy silane (TEOS) as starting materials in aqueous medium. The gels prepared by this method were dried at 100°C for 24h and then calcined for 2h at different temperatures ranging from 500°C to 800°C. X-ray powder diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TGA) and infra-red spectroscopy analysis (IR) were utilized to characterize the gel powders and calcined powders. Transmission electron microscope (TEM) was used to measure the average particle size of the calcined powders.

    • Synthesis of mullite powders using precipitated silica and tetraethoxy silane and aluminium-formate as precursor materials in aqueous medium

      N N Ghosh P Pramanik

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      Mullite (3Al2O3-2SiO2) powder was prepared by using an aqueous sol-gel method where aluminium formate and tetraethoxy silane (TEOS) and precipitated silica were used as the precursor compounds and water was used as reaction medium instead of the conventionally used solvent alcohol. The gels were calcined at 1000°C, 1200°C and 1300°C for 1 h and characterized by X-ray powder diffraction, infrared spectroscopy, differential thermal analysis, thermogravimetry analysis and transmission electron microscopy. This method is shown to provide homogeneous, reactive amorphous powder at comparatively low temperatures.

    • Preparation of superconducting-grade copper from commercial grade copper salt

      P Pramanik A K Adak A Pathak

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      Fine samples with nominal composition of Bi1·6Pb0·4Sr2Ca2Cu3Ox have been produced by solid state method using various purity grades of starting copper oxide powder. Studies onTc and high-Tc volume fraction measurements of these samples revealed that the samples produced using CuO powders obtained in laboratory after double purification of the commercially available copper salts have higherTc (104·46 K) and increased percentage of highTc volume fraction (58%) compared to even the samples prepared from Aldrich grade (99·99%) CuO. A simple and cost-effective chemical route for the purification of CuO from commercially available copper salts has been outlined.

    • A novel chemical route for the preparation of nanosized oxides, phosphates, vanadates, molybdates and tungstates using polymer precursors

      P Pramanik

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      A variety of nanosized (particle diameter ranging between 10–90 nm) ceramic oxide powders have been prepared from a versatile, efficient and technically simple polymer matrix based precursor solution. The precursor solution constituted of the metal nitrates mixed with the polymer-PVA/PAA/carboxylated starch in presence of mono-/disaccharides or, poly hydroxy compound. Thermolysis/flame pyrolysis of the precursor mass at external temperatures of around 300–500°C resulted in the oxide phase.

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