Original Publication Date
Computational Materials Science
DOI of Original Publication
Date of Submission
In this paper we present the results of calculations of the lattice thermal conductivity of layered complex metal oxide NaxCoO2 within the Green–Kubo theory. Using NaxCoO2 we identify the two competing mechanisms responsible for the favorable scaling properties of the Green–Kubo method for calculating the lattice thermal conductivity. The artificial correlations of the heat flux fluctuations due to the finite size of the supercells are partially cancelled by the missing long wavelength acoustic phonon modes. We compute the lattice thermoelectric properties of bulk NaxCoO2 with varying stoichiometry, structural defects, and temperature. We also calculate the thermal conductivity of NaxCoO2 in the nanosheet geometry. While the dependence of thermal conductivity on Na fractions x in the middle range (0.5 < x < 0.8) is relatively weak, introducing Co vacancies results in significant lattice thermal conductivity reduction. The material exhibits strong anisotropy of lattice thermal conductivity due to a layered crystal structure and relatively weak bonding between layers. This structure leads to the possibility of manufacturing relatively large nanosheets of NaxCoO2. However, the weak inter-layer binding also results in the insensitivity of thermal conductivity to the nanosheet thickness.
Copyright © Elsevier Ltd. NOTICE: this is the author’s version of a work that was accepted for publication in Computational Materials Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Computational Materials Science, Volume 82, 1 February 2014, Pages 219–225, doi:10.1016/j.commatsci.2013.09.049.
Is Part Of
VCU Physics Publications