Experimental and theoretical P-V-T equation of state for Os2B3. Issue 1 (2nd January 2021)

• Record Type: Journal Article
• Authors: Burrage, Kaleb C.; Lin, Chia-Min; Chen, Wei-Chih; Chen, Cheng-Chien; Vohra, Yogesh K.
• Is Part Of: High pressure research. Volume 41:Issue 1(2021)
• Page Start: 27
• Page End: 38
• Publication Date: 2021-01-02
• Subjects: Metal borides -- thermal equation of state -- high pressure high temperature -- synchrotron x-ray diffraction; High pressure (Science) -- Periodicals; High pressure (Technology) -- Periodicals; 536.41
• DOI: 10.1080/08957959.2020.1858821
• Languages: English
• ISSNs: 0895-7959

Abstract

ABSTRACT: Thermoelastic behavior of transition metal boride Os2 B3 was studied under quasi-hydrostatic and isothermal conditions in a Paris-Edinburgh cell to 5.4 GPa and 1273 K. In-situ Energy Dispersive X-ray diffraction was used to determine interplanar spacings of the hexagonal crystal structure and the P-V-T data were fitted to a 3rd Order Birch–Murnaghan equation of state with a temperature modification to determine thermal elastic constants. The bulk modulus was shown to be K0 = 402 ± 21 GPa when the first pressure derivative was held to K0 ' = 4.0 from the room temperature P-V curve. Under a quadratic fit α = α 0 + α 1 T − α 2 T − 2, the thermal expansion coefficients were determined to be α 0 = 1.862 × 10 − 5 K −1, α 1 = 0.841 × 10 − 9 K −2, and α 2 = − 0.525 K. Density functional theory (DFT) with the quasi-harmonic approximation (QHA) were employed to study Os2 B3, including its P-V-T curves, phonon spectra, bulk modulus, specific heat, thermal expansion, and the Grüneisen parameter. A good agreement between the first-principle theory and experimental observations was achieved, highlighting the success of the Armiento-Mattsson 2005 generalized gradient approximation functional employed in this study and QHA for describing thermodynamic properties of Os2 B3 .