| Titre : | Calculs ab-initio des propriétés des pérovskites BaXO3 (X : métal de transition) |
| Auteurs : | BENATIA Mohamed, Auteur ; ELKEURTI Mohammed, Directeur de thèse |
| Type de document : | texte manuscrit |
| Editeur : | Université de Saïda– Dr. Moulay Tahar Faculté des Sciences-Spécialité :Physique des matériaux, 2022/2023 |
| Format : | 91 ص |
| Accompagnement : | CD |
| Langues: | Anglais |
| Index. décimale : | BUC-D 000090 |
| Catégories : | |
| Mots-clés: | : First-principles: GGA-PBEsol,Band structure: TB-mBJ: Elas- tic parameters: Thermodynamic properties . |
| Résumé : |
The present study investigates the structural, electronic, elastic, and thermo-
dynamic characteristics of BaXO3 compounds (where X represents (X = Fe, Nb, Mo and Hf)) in their perovskite cubic crystalline phase. The Functional Density Theory is utilized as a component of the FP-LAPW method, executed in the code WIEN2k-14. They use a functional gradient approximation generalized on the Perdew2008 function (GGA-PBEsol). The network parameter, the compressibility modulus, and its derivative are cal- culated. The elastic constants, denoted as (C11, C12 and C44) were calculated to investigate the stability. The anisotropy factor (A), compressibility modulus (B), shear modulus (G), modulus of tetragonal shear (G′), compressibility (β), Young’s modulus (E), Cauchy pressure (CP ), Lamé coefficients (λ, μ), Poisson ratio (σ), and Debye temperature (ΘD) were determined using calculated monocrystalline elastic constants. For the band structure, the density of states, exchange, and cor- relation effects were evaluated using the Tran-Blaha-modified Becke-Johnson potential to describe the energy gaps accurately. The obtained results were com- pared with available experimental data and other theoretical calculations. We utilized the Debye quasi-harmonic model, which is implemented in the GIBBS program, to compute the thermal properties of our compounds. These iii properties include the Gruneisen parameter (γ), the thermal expansion coeffi- cient (α), the pressure specific heat constant (CP ), constant volume specific heat (CV ), isothermal compressibility modulus (BT ), adiabatic compressibility modulus (BS ), and the Debye temperature (ΘD). Our materials exhibit brittleness, mechanical stability, and elastic anisotropy, characterized by a prevalence of directed bonding. Initial estimations of the elastic and thermodynamic parameters.The materials BaFeO3, BaNbO3, and BaMoO3 lack a gap in the vicinity of the Fermi levels, suggesting that they are metallic. The material BaHfO3 exhibits an indirect band gap between the R and Γ points, with a value of 5.66 eV . The highest energy level of the valence band is mainly determined by the O – 2 p states. In contrast, the lowest energy level of the conduction band is predominantly influenced by the Ba – d and Hf – dt2g states. |
Exemplaires (1)
| Code-barres | Cote | Support | Localisation | Section | Disponibilité |
|---|---|---|---|---|---|
| BUC-D 000090 | BUC-D 000090 | CD | Bibliothèque PMB Services | Albums | Libre accès Disponible |
Documents numériques (1)
BUC-D 000090 Adobe Acrobat PDF |
