Theoretical study of the electronic, thermodynamic, and thermo-conductive properties of gamma-LiAlO2 with Li-6 isotope substitutions for tritium production

摘要

Lithium aluminate has attracted researchers' interests due to its wide applications. The structural, electronic, optical, lattice phonon thermodynamic, and thermo-conductive properties of gamma-LiAlO2 with Li-6-isotope substitution are investigated by density functional theory and lattice phonon dynamics. The calculated results show that gamma-LiAlO2 possesses a wide band-gap of 4.63 eV. The valence band is mainly formed by p orbitals of Li, O, and Al. The calculated lattice thermal conductivity of gamma-LiAlO2 is found to be in good agreement over a wide range of temperatures with the available experimental data. The calculated dielectric matrix shows anisotropic behavior along z and x (or y) axes. Due to the wide bandgap, the optical conductivity of gamma-LiAlO2 is mainly contributed from the electron hopping between valence-conduction bands. Substitution of Li-7 with Li-6 isotope in gamma-LiAlO2 leads to observable differences in the lattice phonon frequencies at higher frequencies (>8 THz) and to slight changes in corresponding thermal conductivity and the infrared and Raman spectra which are in good agreement with our experimental measured data. The relevance of these properties for tritium production through Li-6 absorbing neutron in nuclear reactors is discussed. Published by Elsevier B.V.