C.S. Myers

The Ohio State University, Columbus, Ohio, United States

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Publications (3)3.71 Total impact

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    ABSTRACT: In this work, pulse calorimetry was used to measure the specific heats of four superconducting materials at temperatures from 0 to 300 K and in magnetic fields from 0 to 14 T. Specific heat measurements were performed on Bi2212 round wire samples with a two-dimensional random oriented single stack design, made by Supramagnetics Inc., and a conventional design made by Oxford Superconductor. Specific heat measurements were also performed on a copper-stabilized MgB 2 wire sample and a rod-in-tube type Nb3Sn wire sample made by Hyper Tech Research, which were subject to their appropriate heat treatments. All wire sample lengths were ∼3 mm. The specific heats of the Bi2212 samples were relatively independent of applied field; the zero field specific heat of the two-dimensional random oriented single stack sample increased from 0.155 mJ/g-K at 4 K to 254 mJ/g-K at 250 K. At 2 K, the specific heat of the Nb3Snrod-in-tube strand increased from 0.0257 mJ/g-K at 0 T to 0.0716 mJ/g-K at 14 T. In zero field the specific heat of the MgB 2 sample increased from 0.623 mJ/g-K at 4 K to 382 mJ/g-K at 250 K.
    IEEE Transactions on Applied Superconductivity 01/2013; 23(3). DOI:10.1109/TASC.2013.2246812 · 1.24 Impact Factor
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    ABSTRACT: SmFeAsO<sub>1-x</sub>F<sub>x</sub> type oxypnictide bulks were made via a single-step synthesis. Polycrystalline bulk samples with nominal composition SmFeAsO<sub>1-x</sub>F<sub>x</sub> (x=0.35 and 0.4) were synthesized by conventional solid state reaction using the starting powders SmF<sub>3</sub> , Sm, Fe, Fe<sub>2</sub>O<sub>3</sub> , and high-purity As (specifically allotrope-gray arsenic). The weighed powders were thoroughly ground by hand with a mortar and pestle and pressed into pellets in an argon-filled glove box. The pressed pellets were sealed in an evacuated quartz ampoule and heat treated at 1100°C using different ramp rates to reach the reaction temperature. Magnetization vs. temperature measurements were made on the various specimens, where a maximum onset T<sub>c</sub> of 55 K was achieved.
    IEEE Transactions on Applied Superconductivity 07/2011; 21(3-21):2853 - 2857. DOI:10.1109/TASC.2010.2080253 · 1.24 Impact Factor
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    ABSTRACT: In this work, a new strand design for Bi-2212 conductors was studied. The new design had a single stack approach with randomly oriented but densely packed two-dimensional Bi-2212 filaments. This Bi-2212 Two-Dimensional Random-Oriented Single-Stack (2D-ROSS) Round Wire design led to high levels of grain texture and significant amounts of Ag-superconductor interface within the filaments, while maintaining a high strand fill factor. This new design was compared to a strand made with a conventional billet layout. Heat treatments were performed under 100% flowing oxygen, and the samples were melt processed at 884, 886, 888, and 89°C. The strands were studied via transport, magnetic, and electron optics techniques. The strands manufactured with the new process showed higher critical currents than the standard design strands in terms of engineering critical current density (J<sub>e</sub>) but slightly lower layer critical current density (J<sub>c</sub>). However both strand sets were limited by filament sizes which were not yet optimized and excessive C-content in the powders. J<sub>e</sub> values of 48 A/mm<sup>2</sup> for the new strand design, and 26 A/mm<sup>2</sup> for the conventional double stack design, at 12 T and 4.2 K were observed. An interesting property of the new strand method was that the strands were less sensitive to small heat treatment, HT, temperature variations in terms of their final J<sub>c</sub> properties. Magnetic and microstructure/phase assemblage studies observed less filament bridging in the new strand design as compared to the conventional one.
    IEEE Transactions on Applied Superconductivity 07/2011; 21(3-21):2804 - 2807. DOI:10.1109/TASC.2010.2093494 · 1.24 Impact Factor