Table of Contents - Volume 13 Number 1

Ultrathin films (50-150nm thick) cuprous oxide (Cu₂O) thin films were deposited by low temperature thermal oxidation technique. The structural, optical and photoelectrochemical properties of the thin films were investigated. X-ray diffraction (XRD) and high resolution scanning electron microscope (SEM) was used to study the phase composition and the thin films’ microstructure respectively. XRD results showed that Cu₂O was the dominant phase albeit some trace CuO peaks were also observed indicating surface formation of an extremely layer of CuO probably during the cooling process following either deposition or during the annealing steps. SEM showed a highly nanostructure consisting long narrow nanorods with broadening to the surface but with extremely narrow, sharp cylindrical roots standing on the substrate. Photoelectrochemical properties of the films were studied via a standard three electrode using a saturated calomel cell (SCE).

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Hydroxyapatite (HAp) was prepared from egg shells by various routes using hexane and acetic acid followed by heat treatment. HAp has a wide application in water treatment by removal of metal ions. XRD of the samples showed use of acetic acid followed by high temperature sintering leads to formation crystalline phases of HAp. Strong evidence of CaCO₃ in calcite phase was obtained in other samples. Zinc oxide nanoparticles have also been synthesized by different methods such as sol-gel, co- precipitate   and green synthesis. The effect of different synthesis methods were investigated using X-Ray Diffraction (XRD). The structural properties of nanoparticles including particle size were calculated from XRD data. The XRD reveals that the prepared ZnO samples were highly crystalline, having wurtzite crystal structure. The comparative analysis shows variations in particle size with different synthesis methods.

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Orthorhombic phase of lead metaniobate (PbNb₂O₆) is piezoelectric with a high Curie temperature (>570°C) with high potential of wide use in important high temperature applications that cannot be covered by the popular piezoelectric materials based on BT and PZT. Difficulty of preparing it in pure phase hindered full characterisation and wide use of this long known piezoelectric material. Here,PbNb₂O₆ pellets have been prepared in pure orthorhombic phase and first characterised by room temperature TEM and XRD techniques, with a satisfying agreement of the two results. Next, we carried out high temperature x-ray diffraction study of its ferroelectric to paraelectric phase transition on heating across the Curie temperature, and also trace the cooling path.On heating the sample to 590°C and cooling back, there is a significant increase of cell volume.

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Polymer electrolytes based on polyvinyledene fluoride (PVdF) and ammonium fluoride (NH₄F) have been prepared and characterized. Films of polyvinyledene fluoride and ammonium fluoride have been prepared by solution casting technique using tetrahydrofuran (THF) as a solvent. Maximum conductivity of 1.17 x 10^-7 S/cm at room temperature has been obtained for polymer electrolytes containing 10wt% NH₄F. The conductivity of polymer electrolyte has been increased by three orders of magnitude from 10^-7 to 10^-4 S/cm with the addition of dimethylformamide (DMF) as plasticizer. The increase in conductivity has been explained to be due to the dissociation of undissociated salt/ion aggregates present in the polymer electrolytes with the addition of high dielectric constant plasticizer (DMF). Maximum conductivity of 1.26 x 10^-4 S/cm has been observed for plasticized polymer electrolytes. The variation of conductivity with temperature suggests that these polymer electrolytes are thermally stable and small change in conductivity with temperature is suitable for their use in practical applications like solid state batteries, fuel cells, electrochromic devices, supercapacitors etc.

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In this work, a novel method for the preparation of colloids has been studied for the fabrication of silicon nitride –Boron nitride composites. In the present work, the dispersion of mixed silicon nitride –Boron nitride powders in aqueous media was studied with the changes dispersant concentration, solution pH etc. Polyethylenimine (PEI) additive as a dispersant were used for Si₃N₄ and BN powders in aqueous media. Well-dispersed Si₃N₄ and BN powders in aqueous media were attained atthe 1 wt% PEI and pH 9. 40 vol% covered Si₃N₄/BN slurries with varying BN content was adapted for gel casting. The gel casted material waspreheated at normal room temperature, debindered at 600⁰C and sintered at 1700⁰C. The sintered composite material composed mainly of alpha-Si₃N₄, beta-Si₃N₄, and h-BN. The prepared composite material shows uniform microstructure with faceted particles, α-Si₃N₄ and abundant pores.

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A big challenge, academic world and industry is facing the relationship of modern societies to the environment that requires reinventing the manufacture and use of materials. Synthetic methodologies now a day should be designed to use and generate substances that possess little or no toxicity to human health and the environment The miceowave assisted synthesis and characterization of Zn (II) complexes of Schiff bases derived from three diuretic drugs acetazolamide, furosemide and hydrochlorothiazide are reported here. The ligand and complexes have been suitably synthesized and isolated in crystalline form. Molar conductance values suggest the non-electrolytic nature of the complexes.On the basis of elemental analyses, electrical conductivity data and molecular weight data the adducts are assigned to the general composition [M(L)₂].All the adducts are diamagnetic in nature. The IR studies indicate that ligand is coordinated to metal through azomethine nitrogen atom. The diuretic activity of the ligand FSM-SA and complex FSM-SA-Zn was assessed in vivo following the protocol of Institutional Animal Ethical Committee norms. While studying the results of the experiment it was concluded the diuretic activity of the FSM-SA and FSM-SA-Zn was found to be more than the parent drug. Partical size studies further suggest that the size of metal complexes is smaller than the drug molecule.

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Ruthenium oxide, Manganese oxide and (Ru:Mn)O2 composite thin films have been prepared by 0.02M Ruthenium chloride and Manganese acetate solutions respectively on stainless steel substrates by sol-gel spin coating method. Layer by layer deposition of RuO2 and MnO2 was done for composite films. RuO2: MnO2 composite thin films have been demonstrated to be an excellent material for Supercapacitor application when evaluated with RuO2 and MnO2 thin film electrodes with respect to XRD, SEM, CV, CP and EIS studies. As a result, high specific capacitance of 515 F/g at 10 mV/s with excellent stability and long cycle life was obtained, where specific power and energy were as high as 15.38 Wh/kg and 4.06 KW/kg respectively with loading weight of 0.13 mg/cm2 .Composite films showed changes in structural and morphological features which was admiring for supercapacitor applications. The electrochemical impedance measurement was carried out in 0.1M KOH in the frequency range 10 to 105 Hz. From the analysis it can be concluded that mixed oxide composites have superior capacitive performance to single transition metal oxides as electrodes.

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Synthesis of polymeric materials from natural renewable resources has attracted a lot of attention of researcher throughout the world as they not only reduce the dependency on petrochemicals but also friendly to the environment. Utilization of non-traditional and non-edible vegetable oils in the synthesis of valuable polymeric materials solves the problem of waste disposal as well as bringing down the cost of end products. Melia azedrach seed oil (MASO), a non-traditional and non-edible seed oil is utilized for the synthesis of poly(ester-amide) (MAPEA) by the aminolysis with diethanolamine followed by step-growth polymerization with phthalicacid. To improve the performances and utility of the MAPEA,methyl methacrylate (MMA) classified as hard monomer in the literature of acrylate embedded to it in different phr to obtained methyl methacrylate modified poly (ester-amide) (MMMAPEA) resins. The MMMAPEA resins were characterized by physic-chemical analysis as per standard reported methods. The structural elucidation of the resin was carried out by spectral analyses. Physico-mechanical and chemical/corrosion resistance performances of the MMMAPEA resins were investigated for the optimization of MMA content.

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