• Anand Kumar

      Articles written in Bulletin of Materials Science

    • High resolution electron microscopic studies of HoAl3, Er0·5Gd0·5Al3 and Y0·91Er0·09Al3 in thin film form

      Anand Kumar Singh Ajay Kumar Singh M S Gupta O N Srivastava

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      Rare earth trialuminides (RAl3) exhibit an interesting series of structures changing from 2H to 3C in the bulk form. Many of the rare earth trialuminides have been recently found to exhibit curious structural characteristics such as the occurrence of the modulated phases. A detailed investigation of the formation synthesis and characterization of some binary and ternary alloys of the rare earth-aluminium system has been carried out. High resolution microscopic technique has been employed to study the modulated phases for some alloyse.g. HoAl3, Er0·5Gd0·5Al3 and Y0·91Er0·09Al3. With the help of lattice imaging technique, several new modulated phases have been investigated. A possible mechanism for the formation of these phases has been suggested. The details of the results obtained by lattice imaging technique are discussed.

    • Growth and characterization of Hg1–𝑥Cd𝑥Te epitaxial films by isothermal vapour phase epitaxy (ISOVPE)

      Manju Malhotra Madhukar Gautam J K Radhakrishnan Vinod Kapoor Sudeep Verma Upendra Kumar Anand Kumar Garima Gupta Anshu Goyal S Sitharaman

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      Growth of Hg1–𝑥Cd𝑥Te epitaxial films by a new technique called asymmetric vapour phase epitaxy (ASVPE) has been carried out on CdTe and CZT substrates. The critical problems faced in normal vapour phase epitaxy technique like poor surface morphology, composition gradient and dislocation multiplication have been successfully solved. The epitaxial films have been electrically characterized by using the Hall effect and capacitance–voltage (𝐶–𝑉) measurements.

    • D.C. conductivity and spectroscopic studies of polyaniline doped with binary dopant ZrOCl2/AgI

      Kiran Kumari Vazid Ali Anand Kumar Sushil Kumar M Zulfequar

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      Aqueous binary dopant (ZrOCl2/AgI) is used in different ratios such as 1:1, 1:2 and 2:1 (w/w) for chemical doping to enhance the conductivity of synthesized polyaniline (PANI). The doping of polyaniline is carried out using tetrahydrofuran as a solvent. Doped samples are characterized using various techniques such as 𝐼–𝑉 characteristics, UV-visible spectroscopy, X-ray diffractometry (XRD), FTIR and photoluminescence (PL) studies. A significant enhancement in d.c. conductivity has been observed with the introduction of binary dopant. UV-visible study shows that optical parameters change considerably after doping. Interestingly, both direct and indirect bandgaps are observed in the doped samples. XRD patterns show the semi-crystalline nature of doped polyaniline. FTIR study shows structural modifications in functional groups with doping in PANI. Photoluminescence spectra exhibit emission properties of the samples.

    • High pressure investigations on neutron irradiated ferroboron

      ANAND KUMAR UTTYIOARNAB SAHA E RADHA K DEVAN N R SANJAY KUMAR C N VENKITESWARAN R DIVAKAR N V CHANDRA SHEKAR

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      This study reports the pressure effect on structural stability of neutron irradiated ferroboron systems. Ferroboron, a mixture of boron and iron, has been found to have three phases, i.e., FeB, Fe$_2$B and Fe$_3$B. Studies have been conducted on single-phase Fe$_2$B and ferroboron. Fe$_2$B adopts tetragonal structure at ambient and undergoes structural transition to orthorombhic phase at 6 GPa. Further, Fe2B is irradiated with neutrons with a fluence of ${\sim}$10$^{17}$ n cm$^{–2}$ and yields bulk modulus of 254 GPa, which is 16% enhancement as compared to unirradiated sample. The defects are estimated by the use of SRIM code. Total displacement per atom (dpa) in Fe$_2$B for the irradiation fluence is found to be 5.53${\times}$10$^{-5}$. The study also shows that phase transition seen in pristine Fe$_2$B is inhibited upon neutron irradiation under pressure up to 24 GPa. Similar result was obtained on ferroboron mixture, irradiated with a neutron fluence of 8.18${\times}$10$^{21}$ n cm$^{-2}$ with dpa of 2.8. The irradiated sample is found to be stable up to 16 GPa.

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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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