Bismuth–Ceramic Nanocomposites with Unusual Thermal Stability via High-Energy Ball Milling

Authors

  • M.A. Meitl,

    1. Department of Materials Science and Engineering, Frederick Seitz Materials Research, Laboratory and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 1304 West Green St., Urbana, IL 61801, USA
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  • T.M. Dellinger,

    1. Department of Materials Science and Engineering, Frederick Seitz Materials Research, Laboratory and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 1304 West Green St., Urbana, IL 61801, USA
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  • P.V. Braun

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  • We thank P. Bellon for his helpful discussions of high-energy ball milling. This material is based upon work supported by the Nanoscale Science and Engineering Initiative of the NSF under Award No. DMR-0117792, the NSF-REU program under Award No. DMR-9733582, and U.S. Department of Energy, Division of Materials Sciences under Award No. DEFG02–91ER45439, through the Frederick Seitz Materials Research Laboratory at the University of Illinois at Urbana-Champaign

Abstract

Electrically conducting nanocomposites of bismuth metal and insulating ceramic phases of SiO2 and MgO were generated via high-energy ball milling for 24 h using zirconia milling media. The resulting nanocomposites contain Bi nanoparticles with sizes down to 5 nm in diameter. The morphology is a strong function of the oxide phase: specifically, the Bi appears to wet MgO while it forms spherical nanoparticles on the SiO2. X-ray diffraction measurements indicate a nominal bismuth grain size of 50 nm, and peak fitting to a simple bidisperse model yields a mixture of approximately 57 % bulk bismuth and 43 % 27 nm diameter crystallites. Nanoparticles as small as 5 nm are observed in transmission electron microscopy (TEM), but may not constitute a significant volume fraction of the sample. Differential scanning calorimetry reveals dramatic broadening in the temperatures over which melting and freezing occur and a surprising persistence of nanostructure after thermal cycling above the melting point of the Bi phase.

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