Li/Na atoms' substitution effects on the structural, electronic, and mechanical properties of the CaSnO3 perovskite for battery applications

Effects of High Hydrostatic Pressure on the Structural, Electronic, and Elastic Properties, and Li-Ion Diffusion Barrier of Lithium Lanthanum Titanate Electrolytes: A DFT Study

“…This dependence between the thermodynamic stability and Li substitutional impurities was also observed for the CaSnO 3 anode with Li/ Na substitutions at the A sites. 51 Besides, for all cases, the thermodynamic stability decreases as pressure increases. Likewise, in the case of LLTO electrolytes, the stability decreases as the octahedral distortion increases (Figs.…”

“…1a), as in previous reports. 16,50,51 In this work, only Li concentration x = 0.50 was considered, for two reasons: (i) to maintain the charge neutrality in the LLTO unit cell through the oxidation states presented by the Li + , La 3+ , Ti 4+ , and O 2− , taking care that the oxygen anions have completed their octet (i.e., eight electrons surround each O atom) and, consequently, their oxidation state 2-(this guarantees the energetic stability of LLTO perovskite); (ii) although the first requirement is met with x = 0.25 (for charge neutrality, the Ti cations have a mixed oxidation state of 3+ and 4+, as described in previous work, 16 where using the formal charges, the unit stoichiometric formula is Li + 0.25 La 3+ 0.75 Ti 3+ 0.5 Ti 4+ 0.5 O 2-3 or Li + La 3+ 3 Ti 3+ 2 Ti 4+ 2 O 2-12 by unit cell), the results showed that this LLTO compound is mechanically unstable. At zero GPa, the LLTO electrolyte presents a low-symmetry structure (triclinic) with 21 independent elastic stiffness coefficients after the geometric optimization process.…”

“…5b-5c and Tables I and II). To determine the thermodynamic stability of LTO and LLTO compounds under high hydrostatic pressure, the cohesive energy (E P coh [ ]) was calculated as a function of pressure P, through the following equation, 51 E P…”

“…Besides, E P S [ ] is a quantitative parameter to observe the influence of the position of Li substitutional impurities and hydrostatic pressure effects on Li-O, La-O, and Ti-O bond interactions. 51 Figure 14 shows the correlation between the E S and E coh under hydrostatic pressure. It is observed that at zero GPa, by Li substitutional effects, E S show a linear behavior relating to E , coh having the following trend LLTO-RS > LLTO-C > LLTO-L.…”

Structural, mechanical and optoelectronic properties of B6X (X = Se, S) chalcogenides under hydrostatic pressure

“…Additionally, the cohesive energy (E coh ), defined as the difference between isolated atom energy and crystal energy, was computed according to the equation [43][44][45]:…”