2015-Sustainable Industrial Processing Summit
SIPS 2015 Volume 8: Composite & Ceramic, Quasi-crystals and Nanomaterials
| Editors: | Kongoli F, Pech-Canul M, Kalemtas A, Werheit H |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2015 |
| Pages: | 300 pages |
| ISBN: | 978-1-987820-31-7 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Elastic and Spectroscopic Properties of B4C up to 70 GPa: Emphasis on the Equation of State and Distortional Transition(s)
Murli Manghnani1;1UNIVERSITY OF HAWAII-MANOA, Honolulu, United States;
Type of Paper: Regular
Id Paper: 276
Topic: 18
Abstract:
We review the numerous static and dynamic studies on the polycrystalline and single-crystal specimens of B4C, address the important issues and discuss their implications in terms of the strain-induced changes in their crystallographic parameters and structure, transport properties and electronic structure. We will rely on an integrative analysis of the collaborative in-situ high-pressure studies involving synchrotron x-ray diffraction, ultrasonics, Raman and Brillouin scattering and electrical resistivity in diamond-anvil cell, in conjunction with theory.
Specifically, synchrotron X-ray diffraction (XRD) and Raman spectroscopy measurements have been carried out on polycrystalline B4C and single-crystal (nearly stoichiometric) in a diamond-anvil cell to 70 GPa. These results, in conjunction with high-pressure ultrasonic, Brillouin measurements, are compared with shock wave data in order to understand the compression behavior, establish the equations of state and explain the observed poor ballistic performance.
Whereas the powder XRD data indicate no easily detectable discontinuous changes within the studied pressure range, the Raman spectroscopy, electrical conductivity measurements and shock wave data suggest a more complex behavior. Motivated by this discrepancy, a detailed strain/stress analysis based on the peak profile broadening was performed, revealing two regions of discontinuous strain change, which cannot be explained by the transformations of pressure transmitting medium. These changes can be tentatively related with electronic transformations and changes in bonding. Preliminary results from the electrical resistivity and optical measurements support this interpretation.