• M J Joshi

      Articles written in Bulletin of Materials Science

    • Growth and characterization of gel grown pure and mixed iron–manganese levo-tartrate crystals

      S J Joshi B B Parekh K D Vohra M J Joshi

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      Several applications of iron tartrate and manganese tartrate compounds are reported in the literature. In the present investigation, we have grown pure and mixed iron (II)–manganese levo-tartrate crystals by single diffusion gel growth technique. Crystals with spherulitic morphology were harvested. The colouration of the crystals changed from black to pinkish brown upon increasing the content of manganese in the crystals. The crystals were characterized by FTIR spectroscopy, powder XRD, TGA, VSM and dielectric study. Crystal structures of different mixed crystals were studied. From TGA it was observed that on heating the hydrated crystals became anhydrous and then converted into oxides. Paramagnetic nature of the crystals was revealed from VSM study. The variation of the dielectric constant with frequency was studied. The results are discussed.

    • Thermal, FT–IR and SHG efficiency studies of L-arginine doped KDP crystals

      K D Parikh D J Dave B B Parekh M J Joshi

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      Potassium dihydrogen phosphate (KDP) is a well known nonlinear optical (NLO) material with different applications. Since most of the amino acids exhibit NLO property, it is of interest to dope them in KDP. In the present study, amino acid L-arginine was doped in KDP. The doping of L-arginine was confirmed by FT–IR and paper chromatography. Thermogravimetry suggested that as the amount of doping increases the thermal stability decreases as well as the value of thermodynamic and kinetic parameters decreases. The second harmonic generation (SHG) efficiency of L-arginine doped KDP crystals was found to be increasing with doping concentration of L-arginine. The results are discussed here.

    • Thermal, FT–IR and dielectric studies of gel grown sodium oxalate single crystals

      B B Parekh P M Vyas Sonal R Vasant M J Joshi

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      Oxalic acid metabolism is important in humans, animals and plants. The effect of oxalic acid sodium salt is widely studied in living body. The growth of sodium oxalate single crystals by gel growth is reported, which can be used to mimic the growth of crystals in vivo. The grown single crystals are colourless, transparent and prismatic. The crystals have been characterized by thermogravimetric analysis, FT–IR spectroscopy and dielectric response at various frequencies of applied field. The crystals become anhydrous at 129.3°C. Coats and Redfern relation is applied to evaluate the kinetic and thermodynamic parameters of dehydration. The dielectric study suggests very less variation of dielectric constant with frequency of applied field in the range of 1 kHz–1 MHz. The nature of variation of imaginary part of complex permittivity, dielectric loss and a.c. resistivity with applied frequency has been reported.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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      Posted on July 25, 2019

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