Anisotropic Thermal Expansion of Zirconium Diboride: An Energy-Dispersive X-Ray Diffraction Study

Journal Article · Fri Jan 01 04:00:00 EST 2016 · Journal of Ceramics

DOI:https://doi.org/10.1155/2016/8346563· OSTI ID:1354266

Paxton, William A. ^[1]; Özdemir, Tevfik E. ^[1]; Şavklıyıldız, İlyas ^[1]; Whalen, Terence ^[1]; Biçer, Hülya ^[1]; Akdoğan, Enver Koray ^[1]; Zhong, Zhong ^[2]; Tsakalakos, Thomas ^[1]

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1. Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
2. Photon Sciences, Brookhaven National Laboratory, Upton, NY 11973, USA

Zirconium diboride (ZrB₂) is an attractive material due to its thermal and electrical properties. In recent years, ZrB₂has been investigated as a superior replacement for sapphire when used as a substrate for gallium nitride devices. Like sapphire, ZrB₂has an anisotropic hexagonal structure which defines its directionally dependent properties. However, the anisotropic behavior of ZrB₂is not well understood. In this paper, we use energy-dispersive synchrotron X-ray diffraction to measure the thermal expansion of polycrystalline ZrB₂powder from 300 to 1150 K. Nine Bragg reflections are fit using Pseudo-Voigt peak profiles and used to compute the $a$ and $c$ lattice parameters using a nonlinear least-squares approximation. The temperature-dependent instantaneous thermal expansion coefficients are determined for each $a$ -axis and $c$ -axis direction and are described by the following equations: ${\alpha }_a$ = ( $4.1507\times {10}^{-6}$ + $5.1086$ × ${10}^{-9}(T-293.15)$ )/( $1+4.1507$ × ${10}^{-6}(T-293.15)$ + $2.5543\times {10}^{-9}{(T-293.15)}^2$ ) and ${\alpha }_c$ = ( $4.5374\times {10}^{-6}$ + $4.3004\times {10}^{-9}(T-293.15)$ )/( $1+4.5374\times {10}^{-6}(T-293.15)$ + $2.1502\times {10}^{-9}{(T-293.15)}^2$ ). Our results are within range of previously reported values but describe the temperature anisotropy in more detail. We show that anisotropic expansion coefficients converge to the same value at about 780 K and diverge at higher temperatures. Results are compared with other reported values.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• OSTI ID: 1354266
• Report Number(s): BNL--112782-2016-JA
• Journal Information: Journal of Ceramics, Journal Name: Journal of Ceramics Journal Issue: 8346563 Vol. 2016; ISSN 2090-8628
• Country of Publication: United States
• Language: English

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36 MATERIALS SCIENCE