• R K KOTNALA

      Articles written in Bulletin of Materials Science

    • Synthesis of Y-Ba-Cu-O superconducting material by citrate chemical route—some observations

      R K Kotnala S M Khullar B S Khurana K Jain M Sharma S Singh R C Goel G K Padam R B Tripathi B K Das

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      We present an overview of our powder synthesis procedure and give some initial results concerning the superconducting properties of YBa2Cu3O7−x.

    • Magneto-optical properties of barium ferrite sputtered films

      R K Kotnala

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      Barium ferrite thin films with perpendicular anisotropy were grown on (111) oriented GGG substrate by rf diode sputtering method. Their magnetic properties were measured. Faraday rotation was measured in the wavelength range 460–800 nm for such sputtered thin films. These films were found quite suitable for magneto-optical recording applications.

    • Strain-induced structural, magnetic and ferroelectric properties of heterostructure BST–NZFO nanocomposite thin film at room temperature

      R K KOTNALA G S ARYA J YOGIRAJ N S NEGI

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      Heterostructure Ba$_{0.7}$Sr$_{0.3}$TiO$_3$–Ni$_{0.8}$Zn$_{0.2}$Fe$_2$O$_4$ composite thin films grown on Pt–TiO$_2$–SiO$_2$–Si substrate were prepared by chemical solution process, where Ba$_{0.7}$Sr$_{0.3}$TiO$_3$ layer grew as top/bottom while Ni$_{0.8}$Zn${0.2}$Fe$_2$O$_4$ layer grew as bottom/top. Structural characterization by X-ray diffraction and atomic force microscopy showed the similar crystal structure, different lattice parameters, large lattice strain and small grain size in heterostructures, whatever their deposition sequences. Such heterostructures present simultaneously ferromagnetic and ferroelectric responses at room temperature. Inparticular, an exceptionally large saturation magnetization was observed in one heterostructures film. The growth sequencesof Ba$_{0.7}$Sr$_{0.3}$TiO$_3$ and Ni$_{0.8}$Zn$_{0.2}$Fe$_2$O$_4$ layers on the substrate remarkably affect the magnetic properties of the compositethin films at room temperature.

    • Target phase-induced compositional control in liquid-phase pulsed laser ablation produced titanium ferrite nanomaterials

      ABHISHEK SHUKLA SUBHASH C SINGH R K KOTNALA K N UTTAM CHUNLEI GUO R GOPAL

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      Titanium ferrite nanoparticles (NPs) are synthesized using liquid-phase pulsed laser ablation (LP-PLA)technique with two different lines of approaches for targets: the first target is the pellet made from the mixture of oxides of iron and titanium, while the second target is iron and titanium metal rods. In the second approach of metal rods, the titanium rod was first ablated in double-distilled water and then, the use of obtained colloidal solution of NPs as a medium for the ablation of iron rod. The titanium ferrite nanomaterials produced from these two types of targets are characterized using X-ray diffraction (XRD), ultraviolet–visible absorption spectroscopy (UV–Vis), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy and vibrating sample magnetometer (VSM) measurements. XRD measurements show multiphase structure for as-produced titanium ferrite NPs. The structural, compositional,optical, bonding nature and magnetic properties of nanomaterials produced from two different targets under same experimental conditions are systematically studied. Comparatively higher yield, larger average particle size and smaller saturation magnetism are observed for nanomaterials produced from ablation of interface of metallic targets over the pellet made from the mixture of corresponding metal oxide powders. ATR-FTIR and Raman studies demonstrate synthesis of titanium–iron-oxide phase of titanium ferrite NPs. The results of present research demonstrate collision and intermixing of plasmas from two different species and can be used to produce ferrite NPs of other metals.

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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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