A first principle study of the perovskite lanthanum aluminate

作者：Elias Badal H^*; Ilyas Bahaa M; Saadi Nawzat S

来源：Materials Research Express, 2018, 5(8): 086302.

DOI：10.1088/2053-1591/aad15f

• lanthanum aluminate
• thermal properties
• electronic properties
• elastic properties
• perovskites

A self-consistent first-principles calculation with a precise hybrid PBEsol functional, Density Functional Theory (DFT) have been used to investigate the stability, elastic, mechanical, electronic, acoustic and thermodynamic properties of the cubic perovskite Lithium Aluminate (LaAlO3). An investigation of the stability showed that the computed lattice parameter LaAlO3 is stable, results also show that the lattice of LaAlO3 becomes more distorted and deviates from the hydrostatic behavior as pressure is increased up to 11 GPa, after this limit, the structure encounter a phase shift, which is seen from the nature of the thermal properties of heat capacity. LaAlO3 is thermos conversion-efficient cubic perovskite with its strong phonon scattering interactions resides mostly unclear. The energy band structure appears to display an indirect band gap insulator, with Gamma-R separating the valence and conduction bands. Pressure dependence of cubic elastic Moduli, elastic wave velocities, Debye temperature and the density of states of LaAlO3 were calculated, our results appear to converge with available experimental data. The elastic constants reveal the fact that the crystal is stable and show nature of crispness. The thermal characteristics were computed within the hybrid functional PBEsol using the Debye-Waller model and response functions. Lattice dynamics investigation of the perovskite thermoelectric LaAlO3 are investigated with the single-crystal first-principles simulations and compared against inelastic neutron scattering (INS) at 100 K. Our ab-initio calculations of LaAlO3 show a free asymmetry in the first nearest-neighbor peak. In addition, our first principles calculations data reveal stiffer bonding at the anion sites, which is in good agreement with the partial phonon densities of states from INS. The 4-dimensional phonon-dispersion surfaces of LaAlO3, have been mapped and it is found that the origins of the ionic potential an-harmonicity being responsible for the unique behavior and phonon properties of LaAlO3. The latter results provide clear evidence for the anharmonicity phonon distribution associated with the resonant bonding leading to a ferroelectric nature.

• 出版日期2018-8