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Lithium lanthanum titanate perovskites Li x La1−x TiO3 (LLTO) are promising solid-electrolytes for Li-ion batteries. We studied, in the Density-Functional-Theory framework, the thermodynamic stability and the electronic and magnetic properties of LLTO, as bulk materials and as thin slabs with (001) exposed surfaces. Results show that LaTiO3 (LTO) exhibits semiconductor behavior and G-type antiferromagnetic order (AFMG), whereas the TiO2-terminated LTO slab is a semiconductor with ferromagnetic (FM) order. Contrasting, the LTO slab exposing a LaO-terminated surface is a conductor with AFMG ordered Ti cations' magnetic moments (MMs), but at the surface there are some FM ordered MMs (La atoms). LLTO bulk electrolyte is a semiconductor (x = 0.25) or insulator (x = 0.50). The LLTO slab is a FM (non-magnetic) conductor (TiO2 (LiO)-terminated surface) or a FM semiconductor (LaO-terminated). Besides, the stability of the LLTO bulk and slabs structures was analyzed, as well as the slabs’ preferences for LiO, LaO or TiO2 ends.

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In this work, the electronic and mechanical properties of bulk TiSe2 were studied, and the effects of confinement on the compound, into mono-, bi-, and tri-layered systems, on the electronic and mechanical properties using DFT-based calculations within the Generalized Gradient Approximation (GGA) using Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional. Lithium atoms were placed at different adsorption sites of the TiSe2 monolayer to study the consequences on the electronic and mechanical properties and to identify the most favourable adsorption site for Li in the TiSe2 systems. Mono -, bi-, and tri-layered systems have associated a metallic behaviour, similar to the bulk material. Young’s modulus for mono-, bi-, and tri-layered systems show similar behaviour to the bulk case. On the other hand, monolayers with Li are metallic when Li atoms are placed at the surface; and this behaviour could be favourable to facilitate electronic transport by the monolayer. Finally, the mechanical properties analysis supported that the better adsorption sites are those labelled as Top and Hollow.

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To study the effect of the applied hydrostatic pressure on the crystal structure and the electronic and mechanical properties of the Sr2FeNbO6 compound, computational calculations in the density functional theory framework, with the local density approximation and Hubbard correction as it is treated by the CA-PZ exchange-correlation functional were performed. The tetragonal structure with the I4/m space group is reported stable in the range from zero to 50 GPa according to Born’s stability criterion. No crystal phase transition was found in agreement with experimental data; however, between 20 and 30 GPa, a brittle to ductile transition is confirmed by the Pugh’s criterion and Poisson’s ratio. Moreover, a change from ionic-covalent to metallic bonding is suggested by the Poisson’s ratio. This behavior is reflected in the electronic properties, through the controlled modulation of the energy bandgap (Eg (eV)) as a function of pressure, according to a fitted linear equation, Eg = (−0.016)P + 2.040. At 50 GPa, Eg value is 1.236 eV, very close to the ideal 1.34 eV, which is required for hydrogen generation and photovoltaic applications.

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