| Titre : | Enhancement of superconducting properties of MgNiS by using oxygen annealing atmosphere |
| Auteurs : | Amira SBAIHI, Auteur ; Said Lakel, Directeur de thèse ; Said Benramache, Directeur de thèse |
| Type de document : | Thése doctorat |
| Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider, 2024 |
| Format : | 1VOL.(125p) / ill.couv.ill.en coul / 24.5Cm |
| Langues: | Anglais |
| Langues originales: | Anglais |
| Mots-clés: | NiS Thin Films, spray pyrolysis, Electrical conductivity, Mg level, Annealing atmosphere. |
| Résumé : |
In this study, we explored the physical properties of undoped NiS films produced using spray pyrolysis. X-ray diffraction revealed that all films have a fundamental hexagonal structure with a preferred (010) orientation, and the optimal crystal size was about 22.148 nm. FTIR analysis supported these findings, highlighting the Ni-S bond at 626 cm-1. Optical measurements indicated band gap energies from 0.87 to 0.92 eV. The electrical conductivity results were promising, indicating that NiS thin films are suitable for supercapacitor applications. This study investigated magnesium (Mg) doping effects on nickel sulfide thin films at levels ranging from 2% to 8%. Key findings include a hexagonal polycrystalline structure with smaller crystallite sizes at higher Mg concentrations, notably 14.015 nm at 6%. FTIR analysis confirmed Ni-S bond at 632 cm-1, and band gap energy was observed to vary between 0.882 and 0.994 eV. The lowest electrical resistance measured was 5.569 ohms, also at 6% Mg concentration. Mg-doped NiS thin films annealed in oxygen at 300°C for 3 hours and 30 minutes, and at 350°C for 3 hours, primarily exhibited a NiS structure with a NiO phase. A significant increase in crystallite size was observed, especially at 300°C. This indicates improved crystalline structure, and the films showed good optical band gap properties and favorable sheet resistance (1.87 to 8.30 Ω/sheet). Optimal annealing for supercapacitor applications was found to be 300°C for 3 hours and 30 minutes. |
| Sommaire : |
I.1. Introduction 6 I.2. Presentation of Nickel sulfides 6 I.3. Deposition Method of Nickel sulfides thin films 8 I.3.1. Sol-gel method 9 I.3.2. Chemical Bath Deposition (CBD) 9 I.3.3. Electrodeposition 9 I.3.4. Atomic Layer Deposition (ALD) 10 I.3.5. Successive ionic-layer adsorption and reaction (SILAR) 11 I.3.6. Spray deposition methods (SP) 11 I.4. Nickel Sulfides thin films 13 I.4.1. Structural characteristics Nickel sulfide 13 I.4.2. Optical properties Nickel sulfide 17 I.4.3. Electrical properties Nickel sulfide 19 I.5. Nickel sulfide applications 20 I.5.1. Electrodes of LIBs and Supercapacitors (SCs) 21 I.5.2. Hydrogen Evolution Reaction (HER) 22 I.5.3. Oxygen reduction reaction (ORR) 22 References 24 PartA:Elaboration Techniques33 II.1. Introduction 33 II. 2. Generalities of spray pyrolysis technique 33 II.2.1. Advantages of spray pyrolysis Technique 34 II.2.2. Disadvantages of spray pyrolysis Technique 34 II.2.3. Classification & equipment of the Spray Pyrolysis Technique 34 II.3. Principle of deposition processes in spray pyrolysis 36 II.3.1. Atomization of the precursor solution 36 II.3.2. Aerosol transport of the droplet 36 II.3.3. Decomposition of the precursor to initiate film growth 37 II.4. Protocol methodology 38 II.4.1. Preparation of spray solution 38 II.4.2. Preparation of the Films 40 II.4.3. Oxygen Annealing Atmosphere 42 PartB:Charactirization techniques43 II.1. Introduction 43 II.2. X-Ray diffraction technique (XRD) 43 II.2.1. The Lattice parameters 45 II.2.2. The Crystallites size (D) 46 II.2.3. The dislocations density 47 II.3. Weight difference method 47 II.4. Spectroscopy UV-VISIBLE 48 II.4.1. Principle 48 II.5. Four-probe method 50 II.6. Fourier Transform Infrared Spectroscopy (FTIR) 51 II.6.1. Principle 52 II. 7. Conclusion 53 References 54 III. 1. Introduction 57 III. 2. Experimental Part 57 III. 2. 1. Nickel Sulfide thin films Preparation 57 III. 2. 2. Cracterization techniques 59 III. 3. Results and Discussion 60 III. 3. 1. The structural properties 60 III. 3. 2. Chemical composition 65 III. 3. 3. Optical properties 66 III. 3. 4. Electrical characteristics 68 III. 4. Conclusion 71 References 72 IV.1. Introduction 75 IV.2. Experimental 75 IV.2.1. Synthesis Protocol 75 IV.2.2. Synthesis Mg doped NiS thin films 75 IV. 2.3. Characterization techniques 77 IV.3. Results and discussion 77 IV.3.1. XRD analysis 77 IV. 3.1.1. Lattice parameters & d-spacing : 81 IV.3.1.2. The Texture Coefficient & The Crystallite Size 82 IV.3.1.3. The dislocation densities & Micro-Strain: 84 IV.3.2. Chemical composition 86 IV.3.3. Optical study 87 IV 3. 3. 1. The transmission & The absorption 87 IV.3. 3. 2. The optical band gap & The Urbach energy 89 IV.3.4. Electrical study 91 IV.4. Conclusion 93 References 95 CHAPTER FIVE:Effects of oxygenannealing atmosphereonMg :NiSthinfilms. IV.1. Introduction 98 IV.2. Experimental procedure 98 V. 2. 1. Annealed thin films preparation 98 V. 2 .2. Thin Film characterization 99 V. 3. Results and discussion 1 00 V. 3. 1. XRD analysis 1 01 V. 3. 1 .2. The Crystallite Size & Micro-Strain 1 02 V. 3. 2. Chemical composition of Mg: NiS annealed films 1 05 V. 3. 3. The optical properties of Mg: NiS annealed films 1 05 V. 3. 3.1. UV–vis absorbance 1 05 V. 3. 3. 2. The band gap energy 1 06 V. 3. 3. Electrical study of annealed films 1 09 V. 3. 4. 1. Sheet resistance of Mg: NiS annealed films 1 09 V. 3. 4. 2. The Electrical Conductivity of NiS annealed films 1 11 V.4. Conclusion 1 12 References 1 13 |
| Type de document : | Thése doctorat |
| En ligne : | http://thesis.univ-biskra.dz/id/eprint/6813 |
Disponibilité (1)
| Cote | Support | Localisation | Statut |
|---|---|---|---|
| TPHY/147 | Théses de doctorat | bibliothèque sciences exactes | Consultable |
