• S K Singh

      Articles written in Bulletin of Materials Science

    • Synthesis of SiC from rice husk in a plasma reactor

      S K Singh B C Mohanty S Basu

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      A new route for production of SiC from rice husk is reported by employing thermal plasma technique. The formation of 𝛽-SiC is observed in a short time of 5 min. The samples are characterized by XRD and SEM.

    • Preparation and characterization of polymer composites based on charge-transfer complex of phenothiazine–iodine in polystyrene

      R A Singh R K Gupta S K Singh

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      Polymer composites based on charge-transfer complex of phenothiazine and iodine with polystyrene have been prepared in different weight ratios and characterized by FTIR, XRD, mechanical, microstructure and electrical properties (d.c. as well as a.c.). These composites show semiconducting behaviour as the conductivity increases with increasing temperature. Low percolation threshold (10% wt CTC) has been found indicating that processable conducting polymers with improved mechanical properties can be prepared by this method.

    • Ce-doped LCMO CMR manganites: a consequence of enhanced $T_{c}$ and $T_{\text{IM}}$

      D K Mishra D R Sahu P K Mishra S K Singh B K Mohapatra B K Roul

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      A series of Ce-doped (1–20 mol%) La0.67Ca0.33MnO3 (LCMO) sintered (1400°C) ceramic samples were prepared by the solid-state reaction route. The significant enhancement of metal insulator transition temperature ($T_{\text{IM}} \approx$ 280 K) and Curie transition temperature ($T_{c} \approx$ 270 K) associated with LCMO system by the addition of 10 mol% of Ce has been observed. Further interesting observation showed that both low (≈ 1 mol%) and high (≥ 15 and 20 mol%) level of Ce-doping in LCMO reduced the $T_{\text{IM}}$ appreciably from 280 K to 220 K, and from 100 to 160 K, respectively exhibiting the signature of a unique spin glass transitions at around 30 K. Structural and spectroscopic studies revealed that unreacted CeO2 and MnO2 phases are found to be present in 1, 15, 20 mol% Ce-doped LCMO samples, which is one of the reasons why they show spin glass transition at low temperature. Our present results on bulk Ce-doped (10 mol%) LCMO are found to be encouraging as far as $T_{\text{IM}}$ of epitaxial La0.7Ce0.3MnO3 thin film ($T_{\text{IM}} \approx$ 250 K) is concerned. This finding suggests that single-phase materials of Ce-doped (10 mol%) LCMO can be prepared with enhanced $T_{\text{IM}}$ effectively using solid-state reaction route.

    • Enhanced thermal conductivity of nano-SiC dispersed water based nanofluid

      O Manna S K Singh G Paul

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      Silicon carbide (SiC) nanoparticle dispersed water based nanofluids were prepared using up to 0.1 vol% of nanoparticles. Use of suitable stirring routine ensured uniformity and stability of dispersion. Thermal conductivity ratio of nanofluid measured using transient hot wire device shows a significant increase of up to 12% with only 0.1 vol% nanoparticles and inverse dependence of conductivity on particle size. Use of ceramic nanoparticles appears more appropriate to ensure stability of dispersion in nanofluid in closed loop single-phase heat transfer applications.

    • Hydrogen absorption/desorption characteristics of room temperature ZrMn2-𝑥Ni𝑥 system (𝑥 = 1.25-1.50)

      Vinod Kumar D Pukazhselvan A K Tyagi S K Singh

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      The present communication deals with the hydrogen storage characteristics of C15 laves phase ZrMn2-𝑥Ni𝑥 system tailored within the x values of 1.25 to 1.50. Drastic variations in thermodynamics of the hydride phase is observed for any little changes of concentration x within this narrow range. The most promising room temperature hydrogen storage materials are found to be formed within the range of 1.35 to 1.45 where ∼ 2.5 to 2.9 H/F.U. can be reversibly stored under the ideal operating conditions. The heat of the reaction is found to be ∼ 17 kJ/mol, which means these are promising candidates for stationary and short range mobile applications. The phase structural features and the thermodynamic aspects of all the materials are discussed in detail.

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