• Sumitra Phanjoubam

      Articles written in Bulletin of Materials Science

    • Higher d.c. resistivity of Li–Zn–Cd ferrites prepared by microwave sintering compared with conventional sintering

      Mamata Maisnam Sumitra Phanjoubam

      More Details Abstract Fulltext PDF

      Cd2+-substituted Li–Zn ferrites having the general formula Li$^{+}_{0.4–x/2}$Zn$^{2+}_{0.2}$Cd$^{2+}_{x}$Fe$^{3+}_{2.4–x/2}$O$^{2-}_{4}$ where x = 0.02, 0.03 and 0.04 have been prepared by both microwave sintering and conventional sintering. In the former case, sintering was done at 1050 °C for 25 min, whereas in the latter case sintering was done at 1050 °C for 6 h. The various structural properties, microstructures and d.c. resistivity of the samples prepared by the two techniques were compared. The study showed higher d.c. resistivity and higher activation energies in the samples prepared by microwave sintering. The mechanisms pertaining to the results are discussed.

    • Low dielectric loss in nano-Li-ferrite spinels prepared by sol–gel auto-combustion technique

      Mamata Maisnam Nandeibam Nilima Maisnam Victory Sumitra Phanjoubam

      More Details Abstract Fulltext PDF

      Pure and doped nano-Li-ferrite spinels were prepared by the sol–gel auto-combustion technique. The prepared ferrites were pelleted and heat treated at different temperatures. Structural characterization was carried out on the as-prepared samples and also on the heat-treated samples using X-ray diffraction (XRD). The studies confirmed the formation of single phase with spinel structures in all the samples. The crystallite size of the samples evaluated from XRD data was found to be 17–24 nm. Scanning electron microscopic photomicrographs revealed the microstructures and the grain size of these nanoferrites. The room-temperature dielectric constant and dielectric loss tangent, tan δ were measured as a function of frequency in the range 100 Hz–1 MHz. These nanoferrites showed the normal dielectric dispersion behaviour. The observed dielectric constant and dielectric loss tangent were found to be much lower than those measured on substituted Li-ferrites prepared by the conventional ceramic method. The results obtained were discussed in the paper.

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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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