| Titre : | Experimental and Theoretical Study of complex perovskites |
| Auteurs : | Aymen TERKI, Auteur ; Rachid Makhloufi, Directeur de thèse |
| Type de document : | Mémoire magistere |
| Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider, 2025 |
| Format : | 1VOL.(79.p) / ill.couv.ill.en coul / 30cm |
| Langues: | Anglais |
| Langues originales: | Anglais |
| Résumé : |
This thesis presents a combined experimental and theoretical investigation of two triple perovskite compounds, Compound N°1 and Compound N°2, to assess their potential for optoelectronic and energy-related applications. The materials were synthesized by solidstate reaction and characterized using XRD, FTIR, and UV-Vis spectroscopy. Structural analysis confirmed the formation of perovskite phases, and optical measurements showed that Compound N°1 exhibits a broader absorption range and lower band gap than Compound N°2 counterpart, indicating stronger potential for light-harvesting applications. Density Functional Theory (DFT) calculations provided insight into the structural, electronic, optical, and mechanical properties. Although the GGA-PBE functional underestimated the band gaps, both compounds exhibited strong optical activity. Compound N°1 demonstrated superior mechanical strength, ductility, and thermal stability compared to Compound N°2. Moreover, Phonon calculations for Compound N°2 revealed imaginary modes, suggesting that its monoclinic structure may be metastable and require specific synthesis conditions to be realized. |
| Sommaire : |
GENERAL INTRODUCTION................1 Bibliographic References........................................................................................................... 4 I.1. Simple perovskites ............................................................................................................... 6 I.2. Complex perovskites ............................................................................................................ 8 I.2.1. Double perovskites ............................................................................................... 8 I.2.2. Layered perovskites .............................................................................................. 9 I.2.3. Triple perovskites.................................................................................................. 9 I.2.3.1. Triple perovskite formulas .................................................................... 9 I.2.3.2. Properties of triple Perovskites ........................................................... 10 I.2.3.3. Applications of triple perovskites ....................................................... 12 I.3. Triple perovskites with general formula A2A′BB′B′′O9 .................................................. 14 Bibliographic References.......................................................................................................... 17 II.1. Synthesis and characterization ......................................................................................... 20 II.1.1. Synthesis by Solid-State Reaction.................................................................... 20 II.1.2. X-ray powder diffraction .................................................................................. 24 II.1.3. Fourier Transform Infrared Spectroscopy (FTIR) ......................................... 26 II.1.4. UV-Visible Spectroscopy ................................................................................. 28 II.2. Computational code and methods .................................................................................... 32 II.2.1. Density Functional Theory ............................................................................... 32 II.2.1.1. Kohn-Hohenberg first theorem ......................................................... 32 II.2.1.2. Kohn-Hohenberg second theorem .................................................... 33 II.2.1.3. Exchange-Correlation Functional ..................................................... 34 II.2.2. Pseudopotential.................................................................................................. 36 II.2.2.1. Pseudopotential principle .................................................................. 36 II.2.2.1. Pseudopotential types ........................................................................ 36 II.2.3. Calculation code ................................................................................................ 38 II.2.4. Properties ........................................................................................................... 39 II.2.4.1. Structural properties........................................................................... 39 II.2.4.2. Electronic properties .......................................................................... 40 II.2.4.3. Optical properties ............................................................................... 41 II.2.4.4. Mechanical properties........................................................................ 44 II.2.4.5. Phonon ................................................................................................ 47 Bibliographic References.......................................................................................................... 48 III.1. Synthesis and characterization ....................................................................................... 51 III.1.1. Synthesis steps ................................................................................................. 51 III.1.2. X-ray powder diffraction ................................................................................. 54 III.1.3. Fourier Transform Infrared Spectroscopy (FTIR) ........................................ 58 III.1.4. UV-Visible Spectroscopy ................................................................................ 59 III.2. Computational results ..................................................................................................... 61 III.2.1. Structural properties ........................................................................................ 61 III.2.2. Electronic properties ........................................................................................ 63 III.2.3. Optical Properties ............................................................................................ 64 III.2.4. Mechanical properties ..................................................................................... 72 III.2.5. Phonon .............................................................................................................. 77 Bibliographic References.......................................................................................................... 78 GENERAL CONCLUSION .................................................................................................. 79 |
| Type de document : | Mémoire master |
Disponibilité (1)
| Cote | Support | Localisation | Statut |
|---|---|---|---|
| MCH/692 | Mémoire master | bibliothèque sciences exactes | Consultable |
