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Title: Thermoelasticity and anomalies in the pressure dependence of phonon velocities in niobium

Authors:
ORCiD logo [1];  [2];  [2];  [3];  [4];  [2]
  1. Mineral Physics Institute, State University of New York, Stony Brook, New York 11794, USA, Academy for Advanced Interdisciplinary Studies, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
  2. Mineral Physics Institute, State University of New York, Stony Brook, New York 11794, USA
  3. Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA, Department of Materials Science and Engineering, State University of New York, Stony Brook, New York 11794, USA
  4. Academy for Advanced Interdisciplinary Studies, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1415504
Grant/Contract Number:
NA0002907
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 112; Journal Issue: 1; Related Information: CHORUS Timestamp: 2018-01-03 11:13:31; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Zou, Yongtao, Li, Ying, Chen, Haiyan, Welch, David, Zhao, Yusheng, and Li, Baosheng. Thermoelasticity and anomalies in the pressure dependence of phonon velocities in niobium. United States: N. p., 2018. Web. doi:10.1063/1.5009617.
Zou, Yongtao, Li, Ying, Chen, Haiyan, Welch, David, Zhao, Yusheng, & Li, Baosheng. Thermoelasticity and anomalies in the pressure dependence of phonon velocities in niobium. United States. doi:10.1063/1.5009617.
Zou, Yongtao, Li, Ying, Chen, Haiyan, Welch, David, Zhao, Yusheng, and Li, Baosheng. 2018. "Thermoelasticity and anomalies in the pressure dependence of phonon velocities in niobium". United States. doi:10.1063/1.5009617.
@article{osti_1415504,
title = {Thermoelasticity and anomalies in the pressure dependence of phonon velocities in niobium},
author = {Zou, Yongtao and Li, Ying and Chen, Haiyan and Welch, David and Zhao, Yusheng and Li, Baosheng},
abstractNote = {},
doi = {10.1063/1.5009617},
journal = {Applied Physics Letters},
number = 1,
volume = 112,
place = {United States},
year = 2018,
month = 1
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on January 3, 2019
Publisher's Accepted Manuscript

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  • The method of electron tunneling is used to study the electron--phonon interaction in niobium and tantalum in the pressure interval 0--9 kbar. It is shown that the superconductivity of these metals is caused by the electron--phonon Cooper pairing mechanism. The method of determining the electron--phonon interaction function from tunnel spectroscopy data of these superconductors is improved.
  • The thermoelastic properties of bcc tantalum have been investigated over a broad range of pressures (up to 10 Mbar) and temperatures (up to 26,000 K) using a new first-principles approach that accurately accounts for cold, electron-thermal, and ion-thermal contributions in materials where anharmonic effects are small. Specifically, we have combined ab initio full-potential linear-muffin-tin-orbital (FP-LMTO) electronic-structure calculations for the cold and electron-thermal contributions to the elastic moduli with phonon contributions for the ion-thermal part calculated using model generalized pseudopotential theory (MGPT). For the latter, a summation of terms over the Brillouin zone is performed within the quasi-harmonic approximation, where eachmore » term is composed of a strain derivative of the phonon frequency at a particular k point. At ambient pressure, the resulting temperature dependence of the Ta elastic moduli is in excellent agreement with ultrasonic measurements. The experimentally observed anomalous behavior of C{sub 44} at low temperatures is shown to originate from the electron-thermal contribution. At higher temperatures, the main contribution to the temperature dependence of the elastic moduli comes from thermal expansion, but inclusion of the electron- and ion-thermal contributions is essential to obtain quantitative agreement with experiment. In addition, the pressure dependence of the moduli at ambient temperature compares well with recent diamond-anvil cell measurements to 1.05 Mbar. Moreover, the calculated longitudinal and bulk sound velocities in polycrystalline Ta at higher pressure and temperature in the vicinity of shock melting ({approx} 3 Mbar) agree well with data obtained from shock experiments. However, at high temperatures along the melt curve above 1 Mbar, the B{prime} shear modulus becomes negative indicating the onset of unexpectedly strong anharmonic effects. Finally, the assumed temperature dependence of the Steinberg-Guinan strength model obtained from scaling with the bulk shear modulus is examined at ambient pressure.« less