| Titre : | THE EFFECT OF LITHIUM DOPING ON THE PROPERTIES OF TITANIUM DIOXIDE THIN FILMS ELABORATED BY SOL-GEL (SPIN COATING). |
| Auteurs : | Manel Saihi, Auteur ; Hanane Saidi, Directeur de thèse |
| Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider, 2024 |
| Format : | 1VOL.(48p) / ill.couv.ill.en coul / 30cm |
| Langues: | Anglais |
| Langues originales: | Anglais |
| Mots-clés: | The keywords:TiO2, thin films, spin coating, doping, structural properties, and optical properties. |
| Résumé : |
In this study, we deposited undoped and Lithium-doped titanium dioxide thin films with doping concentrations varied (0.5%, 1%, 1.5%, 2%) onto glass substrates using the sol-gel (spin coating) method. The influence of Li doping on structural, optical, and morphological properties was investigated and then characterized using X-ray diffraction, UV-visible spectroscopy, and Scanning Electron Microscopy (SEM). X-ray analysis showed that both doped and undoped titanium dioxide thin films crystallize with the tetragonal structure of the anatase phase with a preferential orientation (101), with doping concentrations of 1.5% exhibiting the highest crystallinity. The size of the crystals was calculated, with the high-intensitypeak at a value of 23.27 nm for 2% doping, and the micro-strain values changed inversely with crystal size. UV-visible spectroscopy analysis revealed that the doped and undoped titanium dioxide thin films exhibited high transmittance of up to 87%. In addition, we observed a shift towards longer wavelengths at the absorption edge. This technique was also utilized to calculate the band gap of the prepared thin films, indicating a decrease from 3.44 eV to 3.28 eV and an increase in the Urbach energy from 0.154 eV to 0.186 eV. An SEM image of doped and undoped titanium dioxide thin films revealed that the films are homogenous, smooth granular surfaces, continuous, dense, and have some agglomerations. In summary, the results demonstrate that doping titanium dioxide with lithium improves the material's properties and enhances its efficiency in various applications. The prepared slices exhibited optical properties, while electrical measurements were inconclusive due to the specific conditions required for measurement. The study concludes that the sol-gel method is an effective technique for doping titanium oxide bwith lithium, and the produced slices possess physical and chemical properties suitable for a wide range of technical applications. Further studies are recommended to explore the potential for improving these materials' properties and practical applications. |
| Sommaire : |
I.1. TRANSPARENT CONDUCTING OXIDES (TCOS) ......................3 Ⅰ.1.1. Application of Transparent Conducting Oxides (TCOs) ......3 Ⅰ.1.2. Type of Transparent Conducting Oxides (TCOs)..............4 I.2. TITANIUM DIOXIDE .................4 I.2.1. Properties of Titanium dioxide ..............5 Ⅰ.2.1.1. Structural properties ......................5 I.2.1.2 Optical properties .........................6 I.2.1.3. Electronic properties .....................7 Ⅰ.2.2. Applications of titanium dioxide .............8 I.3. DOPING ...................9 Ⅰ.3.1. Lithium ...............10 II.1. THIN FILMS .............13 II.1.1. Thin Films and its Properties ..............13 Ⅱ.1.2. Thin film growth mechanisms and modes .......13 II.1.3. Thin films applications ....................14 II.1.3.1 Photocatalytic applications ...............14 II.1.3.2 UV protection ................15 II.1.3.3 The photochemistry ...........15 II.1.3.4 solar cells ..................15 Ⅱ.1.4. Thin Films Deposition Process .............15 Ⅱ.1.4.1. Physical deposition Method (PVD) ........16 Ⅱ.1.4.2. Chemical Deposition Method (CVD) ........17 II.2. SOL-GEL METHOD ................18 II.2.1. The principle of Sol-Gel ....18 II.2.2. Sol-Gel process .............18 II.2.2.1. Solution based on an Inorganic (or colloidal) precursor .......19 II.2.2.2. Solution based on an organic (or polymeric) precursor .........19 II.2.3. Chemical reactions in the Sol-Gel .........19 II.2.3.1. Hydrolysis ......................19 II.2.3.2. TheCondensation .................19 II.2.4. Sol-Gel Transition.................20 II.2.5. Heat treatment ....................21 II.2.5.1. Drying ..........................21 II.2.5.2. Annealing .......................21 II.2.6. Deposition of Thin Films by Sol-Gel .......21 II.2.6.1. Dip-coating process .....................22 II.2.6.2. Spin coatingprocess .....................22 II.3. CHARACTERIZATION OF THIN FILM PROPERTIES. .........23 Ⅱ.3.1. Adhesion test .........24 Ⅱ.3.2. Structural characterization................24 Ⅱ.3.2.1. X-Ray diffraction ...........24 II.3.2.2. Bragg's Law ..........25 Ⅱ.3.2.3. Determination of the crystal size ..........26 Ⅱ.3.2.4. The dislocation density (δ) .........26 Ⅱ.3.2.5. Micro-Strain (ε)....................26 Ⅱ.3.3. Optical properties ..............26 Ⅱ.3.3.1. UV-VisibleSpectroscopy ......26 Ⅱ.3.3.2. The film thickness measurement ............27 Ⅱ.3.3.3. Optical band gap (Eg)...............28 II.3.3.4. Urbach energy (Eu) ................29 Ⅱ.3.4 electrical properties .................30 II.3.5. morphological properties ............31 III.1. EXPERIMENTAL PROCEDURES ..............34 III.1.1. Solutions used in the deposition process. ..............34 III.1.1.1. Titanium Tetra-Isopropoxide (Precursor) ..............34 III.1.1.2 Ethanol (solvent) .....................34 III.1.1.3. Acetylacetone (catalyst) .............35 III.1.1.4. Lithium (doping element) .............35 III.1.2. Preparation of Solution ................36 III.1.2.1. Materials and Concentrations .........36 III.1.2.2. Procedure ......................36 III.1.3. Preparing the substrate. .........37 III.1.3.1. Selection of Substrate for Deposition Solution ..........37 III.1.3.2. Cleaning of the substrates ..........37 III.1.4. Thin film deposition ..................38 III .2 RESULTS AND DISCUSSIONS .................41 III.2.1 Structural characterizations ...........41 III.2.1.1. X-rays diffraction. .................41 III.2.1.2. Crystallite size, dislocation density, and micro-strain ...........42 III.2.2. Optical characterization measurements ...................43 III.2.2.1. Transmittance and reflectance spectra .................43 III.2.2.2. Optical gap energy Eg and Urbach energy Eu ............45 III.2.3. The thickness of the film ................48 III.2.4. Surface morphology .......................49 ANNEX ...........51 ASTM sheets for the TiO2 anatase phase ............51 Name and formula ......51 Crystallographic parameters .......51 Subfiles and quality ..............52 Comments ..........................52 Peak list .........................52 Stick Pattern .....................54 REFERENCES ........................55 Abstract……………………………………………64 |
| Type de document : | Mémoire master |
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| Cote | Support | Localisation | Statut |
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| MPHY/647 | Mémoire master | bibliothèque sciences exactes | Consultable |
