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

• Published in: Journal of nuclear materials 2020-03, Vol.530 (C), p.151963, Article 151963
• Main Authors: Duan, Yuhua, Sorescu, Dan C., Jiang, Weilin, Senor, David J.
• Format: Article
• Language: English
• Subjects: Ab initio thermodynamics; Accuracy; Conduction; Conduction bands; Density functional theory; Energy gap; Heat conductivity; Heat transfer; Hopping conduction; Infrared spectra; Lattice phonon dynamics; Lithium; Lithium isotopes; Mathematical analysis; Nuclear reactors; Optical properties; Phonons; Raman spectra; Raman spectroscopy; Substitutes; Thermal conductivity; Tritium; Valence band; γ-LiAlO2 and 6Li-isotope substitution
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2019.151963

Lithium aluminate has attracted researchers’ interests due to its wide applications. The structural, electronic, optical, lattice phonon thermodynamic, and thermo-conductive properties of γ-LiAlO2 with 6Li-isotope substitution are investigated by density functional theory and lattice phonon dynamics. The calculated results show that γ-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 γ-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 band-gap, the optical conductivity of γ-LiAlO2 is mainly contributed from the electron hopping between valence-conduction bands. Substitution of 7Li with 6Li isotope in γ-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 6Li absorbing neutron in nuclear reactors is discussed. The γ-LiAlO2 enriched with 6Li isotope can absorb neutrons to produce tritium (H13). To accurately analyze the H13 production and transport through ceramic pellets, the structural, electronic, optical, lattice phonon thermodynamic, and thermo-conductive properties of γ-LiAlO2 with 6Li-isotope substitution are investigated by density functional theory and lattice phonon dynamics to determine necessary properties associated to the H13 transport of interest. [Display omitted] •Electronic, lattice phonon thermodynamic, and thermo-conductive properties of γ-LiAlO2 with 6Li-isotope substitution.•6Li-isotope substitution makes differences on its phonon dynamics, thermodynamics and Infrared & Raman spectra.•This is the first approach to calculate the thermal conductivity of γ-LiAlO2. The method can be applied to other materials.•This is the first theoretical study on the effects of 6Li-isotope substitution on the properties of γ-LiAlO2 material.•Results are very useful for further to exploring the 3H production and transport through γ-LiAlO2 ceramic pellets.