• MANJU KUMARI

      Articles written in Bulletin of Materials Science

    • Studies on electrical conductivity and dielectric behaviour of PVdF–HFP–PMMA–NaI polymer blend electrolyte

      S K Tripathi Ashish Gupta Manju Kumari

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      Polymer blend electrolytes composed of poly(vinylidene fluoride-co-hexafluoro-propylene), poly(methyl methacrylate) and 1.0 M NaI as salt have been synthesized using solution caste technique by varying the PVdF(HFP)–PMMA blend concentration ratio systematically. A.c. impedance studies were performed to evaluate the ionic conductivity of the polymer electrolyte films. The highest ionic conductivity at room temperature for [PVdF(HFP)–PMMA(4:1)](20 wt%) – [NaI(1.0M)](80 wt%) system is found to be 1.67 × 10-2 S cm-1. XRD studies reveal complete complexation of the salt in the polymeric blend systems. The temperature dependence conductivity has been performed in the range of 303–373 K and it is observed that it obeys the Arrhenius behaviour. It has been observed that the dielectric constant, 𝜀r and dielectric loss, 𝜀i, increases with temperature in the lower frequency region and is almost negligible in the higher frequency region. This behaviour can be explained on the basis of electrode polarization effects. Plot of real part, 𝑀r and imaginary part, 𝑀i vs frequency indicates that the systems are predominantly ionic conductors. The phenomenon suggests a plurality of relaxation mechanism.

    • Bulk growth of Iminodiacetic acid single crystal and its characterization for nonlinear optical applications

      DEBABRATA NAYAK N VIJAYAN MANJU KUMARI MAHAK VIJ B SRIDHAR GOVIND GUPTA R P PANT

      More Details Abstract Fulltext PDF

      A bulk size transparent nonlinear organic single crystal of Iminodiacetic acid was harvested using slow evaporation solution growth technique in controlled atmosphere with a span of 4 weeks. The structural properties of titled crystal were examined by single-crystal X-ray diffraction. The quality of the ingot was determined by high-resolution X-ray diffraction and found that the sample is free from grain boundaries. From UV–Vis analysis, one can understand that there is less absorption in the entire wavelength range of visible region and observed cut-offwavelength is 242 nm. From photoluminescence analysis, the emission of wavelength is identified at 421 nm. Mechanical strength and various parameters like work-hardening coefficient and stiffness constant of ingot was measured using Vickers microhardness test and corresponding experimental data had been explained using distinct theoretical models. The variation measurement of dielectric constant and dielectric loss in respect of frequency was carried out to compute the electronic polarizability of titled compound using Penn model. The detailed analysis of third-harmonic generation was executed using Z-scan method. The values of nonlinear refractive index ($n_2$) and twophoton absorption coefficient ($\beta$) were obtained to be $2.19\times 10^{-17}$ cm$^2$ W$^{-1}$ and $4.25 \times 10^{-12}$ cm W$^{-1}$, respectively.The higher value of coupling factor suggests nonlinear absorption is more dominant and the crystal is suitable for optical limiting application.

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      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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