Articles written in Bulletin of Materials Science

    • Electrical and magnetic properties of polyvinyl alcohol–cobalt ferrite nanocomposite films


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      Polyvinyl alcohol (PVA)–cobalt ferrite (CFO) nanocomposite films were synthesized by wet chemical method. The synthesized CFO nanomaterial was characterized by X-ray diffraction (XRD) and transmission electron microscopy(TEM), which confirm the formation of pure phase nanoparticles with cuboid shape. The variation in AC conductivity is measured as a function of frequency (within the range of 100 Hz$^{–1} MHz) and temperature (from 303 to 403 K). It was observed that the frequency exponent, $S$, decreases with increasing temperature, which is explained by correlated barrier hopping (CBH) conduction mechanism. Frequency dependence of real and imaginary parts of the dielectric permittivity of PVA–CFO nanocomposite films for different temperatures is studied on the basis of the modified Cole–Cole model. The dielectric permittivity of the samples reveals an increasing tendency with the concentration of CFO filler in PVA matrix. A high value of 89 emu g$^{−1}$ saturation magnetization and 652 Oe coercivity are observed in CFO nanoparticle.The coercivity increased in PVA–CFO nanocomposite when compared to CFO nanoparticle, which is expected due to inverse magnetostrictive effect. The increasing tendency of dielectric constant and magnetization of the nanocomposites with the increasing CFO concentration enhances the potential of applications in miniaturization of the antenna system and electromagnetic shielding materials.

    • Enhanced electrical and magnetic properties of Sm-doped YCrO$_3$ nanoparticles


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      In the present work, samarium (Sm)-modified YCrO$_3$ nanoparticles have been investigated. The pristine and Sm-doped YCrO$_3$ nanoparticles were synthesized by the sol–gel method. The phase purity and microstructure of the nanoparticles were analysed by X-ray diffraction (XRD), transmission electron microscope (TEM) investigations. To understand the detailed charge transport mechanism, dc and ac electrical properties were measured. The dc electrical conductivity was found to arise due to an adiabatic small polaronic conduction mechanism. On the other hand, the correlated barrier hopping (CBH) conduction model is used to explain the ac conduction process as a function of frequency (20 Hz–1 MHz) and temperature (298–523 K). The dielectric behaviour of the nanoparticles is followed by the modified Cole–Cole model. With the increase in Sm doping, dielectric permittivity and both free charge and space charge conductivity values increase. The shifting of the peak with frequency in ${\varepsilon}'$ vs. temperature curve, confirmed the existence of a relaxor-like ferroelectric behaviour in the doped YCrO$_3$ nanoparticles. The clear hysteresis loop observed at 80 K delineates the ferromagnetic ordering in the chromate system. The magnetic study suggests that magnetization values increase due to Sm doping. The observation of magneto-dielectric constant in the investigated nanoparticles opens up its potentiality for future spintronics devices.

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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

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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