Atomistic Simulation of the Structural, Thermodynamic, and Elastic Properties of Li₂TiO₃

Abstract

Lithium-based ceramics, such as lithium metatitanate, have been proposed for adoption in the breeder blanket region of a fusion reactor. In this article, we report a combination of empirical and density functional theory (DFT) simulations employing "on-the-fly" pseudopotentials for Li 2 TiO 3 . The smoothing parameters of the planewave pseudopotentials were optimized to ensure an appropriate level of precision for determination of structural, thermodynamic, and elastic properties. As the elastic properties of lithium metatitanate are not well-known, the efficacy of the DFT simulations employing the new pseudopotentials was explored using Li 2 O and TiO 2 where experimental data are available. These pseudopotentials are then used to investigate the three intermediate temperature phases of Li 2 TiO 3 (i.e., C2/c, C2/m, and P3 1 12). Finally, we examine the elastic properties of Li 2 TiO 3 using both DFT and an empirical potential model and find it to be, irrespective of space group, more resistant to deformation than other promising ceramic breeder materials.

Lithium Hexastannate: A Potential Material for Energy Storage

“…The force‐field method provides us with expectation values of the mechanical properties in the case of Li 2 Ti 6 O 13 . The negative value of C 15 for Li 2 SnO 3 is analogous to that of the Li 2 TiO 3 structure reported previously . In our previous work, the values of C ij for Li 2 SnO 3 were also calculated via both DFT and the force‐field methods .…”

“…However, for Li 2 SnO 3 , the difference in the values calculated by DFT and force‐field methods can be attributed to the contraction in the c axis. Both Li 2 SnO 3 and Li 2 TiO 3 exhibit a similar c ‐axis contraction in the C 2/ c space group . In general, the calculated values are consistent for this type of structure.…”

“…The negative value of C 15 for Li 2 SnO 3 is analogous to that of the Li 2 TiO 3 structure reported previously. [31] In our previous work, the values of C ij for Li 2 SnO 3 were also calculated via both DFTand the forcefield methods. [12] The small discrepancies in the C ij values obtained using DFT are attributed to the use of different exchange-correlation functionals.…”

Phase stability and the arsenic vacancy defect in InxGa1−xAs

“…20 A MonkhorstPack 21 scheme is used to sample the Brillouin zone with a density of ≈0.03Å −1 on each axis, corresponding to 3 × 3 × 3 and 2 × 2 × 2 k-point grids for the 64 and 216 atom supercells, respectively. Pseudopotentials were developed using the "onthe-fly" pseudopotential generating feature in CASTEP and the smoothing parameters were optimized following Murphy et al 22 Semicore 3d and 4d electrons are treated as valence for Ga and In, respectively, and the plane-wave cutoff energy was set to 380 eV, offering a precision of 10 −2 eV per formula unit. Finally, the Fourier transform grid for the electron density is larger than that of the wave functions by a scaling factor of 2.0 (represented in CASTEP using the grid scale parameter).…”

Anisotropic charge screening and supercell size convergence of defect formation energies

“…Li 2 TiO 3 may be described as a distorted rocksalt structure (space group C2/c) with alternating Li, LiTi 2 and O planes [15][16][17] which are clearly visible in in Fig. 1.…”