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Title: Isotope scattering and phonon thermal conductivity in light atom compounds: LiH and LiF

Engineered isotope variation is a pathway toward modulating lattice thermal conductivity (κ) of a material through changes in phonon-isotope scattering. The effects of isotope variation on intrinsic thermal resistance is little explored, as varying isotopes have relatively small differences in mass and thus do not affect bulk phonon dispersions. However, for light elements isotope mass variation can be relatively large (e.g., hydrogen and deuterium). Using a first principles Peierls-Boltzmann transport equation approach the effects of isotope variance on lattice thermal transport in ultra-low-mass compound materials LiH and LiF are characterized. The isotope mass variance modifies the intrinsic thermal resistance via modulation of acoustic and optic phonon frequencies, while phonon-isotope scattering from mass disorder plays only a minor role. This leads to some unusual cases where values of isotopically pure systems ( 6LiH, 7Li 2H and 6LiF) are lower than the values from their counterparts with naturally occurring isotopes and phonon-isotope scattering. However, these differences are relatively small. The effects of temperature-driven lattice expansion on phonon dispersions and calculated κ are also discussed. This work provides insight into lattice thermal conductivity modulation with mass variation and the interplay of intrinsic phonon-phonon and phonon-isotope scattering in interesting light atom systems.
Authors:
 [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 17; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1334472
Alternate Identifier(s):
OSTI ID: 1331232

Lindsay, Lucas R. Isotope scattering and phonon thermal conductivity in light atom compounds: LiH and LiF. United States: N. p., Web. doi:10.1103/PhysRevB.94.174304.
Lindsay, Lucas R. Isotope scattering and phonon thermal conductivity in light atom compounds: LiH and LiF. United States. doi:10.1103/PhysRevB.94.174304.
Lindsay, Lucas R. 2016. "Isotope scattering and phonon thermal conductivity in light atom compounds: LiH and LiF". United States. doi:10.1103/PhysRevB.94.174304. https://www.osti.gov/servlets/purl/1334472.
@article{osti_1334472,
title = {Isotope scattering and phonon thermal conductivity in light atom compounds: LiH and LiF},
author = {Lindsay, Lucas R.},
abstractNote = {Engineered isotope variation is a pathway toward modulating lattice thermal conductivity (κ) of a material through changes in phonon-isotope scattering. The effects of isotope variation on intrinsic thermal resistance is little explored, as varying isotopes have relatively small differences in mass and thus do not affect bulk phonon dispersions. However, for light elements isotope mass variation can be relatively large (e.g., hydrogen and deuterium). Using a first principles Peierls-Boltzmann transport equation approach the effects of isotope variance on lattice thermal transport in ultra-low-mass compound materials LiH and LiF are characterized. The isotope mass variance modifies the intrinsic thermal resistance via modulation of acoustic and optic phonon frequencies, while phonon-isotope scattering from mass disorder plays only a minor role. This leads to some unusual cases where values of isotopically pure systems (6LiH, 7Li2H and 6LiF) are lower than the values from their counterparts with naturally occurring isotopes and phonon-isotope scattering. However, these differences are relatively small. The effects of temperature-driven lattice expansion on phonon dispersions and calculated κ are also discussed. This work provides insight into lattice thermal conductivity modulation with mass variation and the interplay of intrinsic phonon-phonon and phonon-isotope scattering in interesting light atom systems.},
doi = {10.1103/PhysRevB.94.174304},
journal = {Physical Review B},
number = 17,
volume = 94,
place = {United States},
year = {2016},
month = {11}
}

Works referenced in this record:

Self-Consistent Equations Including Exchange and Correlation Effects
journal, November 1965

First-Principles Determination of Ultrahigh Thermal Conductivity of Boron Arsenide: A Competitor for Diamond?
journal, July 2013