| Titre : | Effect of doping and sintering temperature on the structural properties of a dielectric ceramic |
| Auteurs : | Fadoua Aridj Hachemi, Auteur ; Abdelhek MEKLID, 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 : | 1 vol. (94 p.) / ill., couv. ill. en coul / 30 cm |
| Langues: | Anglais |
| Langues originales: | Anglais |
| Mots-clés: | perovskite, PZT, dielectric, tetragonal |
| Résumé : |
The main objective of this work focuses on the synthesis and structural and physical characterization of a new PZT-type ceramic material with an ABO3 perovskite structure. More specifically, the study focuses on the ternary system: Pb1-yCay[ZrxTi0.98-x(Fe1/5Zn1/5Sb3/5)0.02]O3, abbreviated as PCZT-FZS, with x = 0.49, 0.50 and y = 0.05. Substitution at the A and B sites was carried out to improve its physical properties. The samples chosen for this study were prepared using a solid-state synthesis method, and at different sintering temperatures: 1100°C, 1150°C, 1200°C and 1250°C respectively in order to optimize the optimum sintering temperature where the density of the samples is maximum (close to the theoretical density) and therefore the product is of better physical quality. Various techniques were used to characterize our samples, including X-ray diffraction (XRD), scanning electron microscopy (SEM) and IR analysis. The results indicate that sample no.1 (49/49) has a tetragonal structure with a density of 77.74%. |
| Sommaire : |
1. Introduction ……………………………………………………………………………………. 4 I.2. Ceramic materials ……………………..……………………..……………………..………….. 4 I.2.1. Definition ……………………..……………………..……………………..……………….... 4 I.2.2. General properties of ceramics ……………………..……………………..………………….. 4 I.2.2.1. Chemical bonds ……………………..……………………..……………………..……….... 5 I.2.2.2. The microstructure ……………………..……………………..……………………..……... 6 I.2.3. Physical properties of ceramics ……………………..……………………..………………..... 7 I.2.3.1. Piezoelectricity ……………………..……………………..……………………..………… 7 I.2.3.1.1. Piezoelectricity and symmetry ……………………..……………………..…………….... 7 I.2.3.2. Pyroelectricity ……………………..……………………..……………………..………….. 9 I.2.3.3. Ferroelectricity ……………………..……………………..……………………..…………. 9 I.2.3.3.1. Ferroelectric domains ……………………..……………………..………………………. 10 I.2.3.3.2. The Curie point ……………………..……………………..……………………..………. 11 I.2.3.4. Dielectricity ……………………..……………………..……………………..……………. 12 I.2.3.4.1. Polarization of a dielectric ……………………..……………………..…………………... 13 I.2.3.4.2. Dielectric properties ……………………..……………………..……………………..….. 14 I.2.3.4.2.1. Relative dielectric permittivity (εr) or dielectric constant ……………………..………... 14 I.2.3.4.2.2. Dielectric losses ……………………..……………………..……………………..……. 15 I.2.3.4.2.3. Dielectric dissipation factor tg δ ……………………..……………………..…………... 15 I.2.3.4.2.4. Dielectric strength ……………………..……………………..……………………..….. 16 I.2.3.5. Ageing ……………………..……………………..……………………..…………………. 16 I.2.3.6. Elasticity ……………………..……………………..……………………..……………….. 16 I.3. Piezoelectric materials: lead zircono-titanates ……………………..……………………..……. 17 I.3.1 Description of perovskite structure ……………………..……………………..…………….... 17 I.3.1.1. Simple perovskites ……………………..……………………..……………………..……... 18 I.3.1.2. Complex perovskites ……………………………………………………………………...... 18 I.3.1.3. Reception rates ……………………..……………………..……………………..…………. 18 I.3.2.Conditions for the structural stability of perovskite ……………………..……………………. 18 I.3.2.1. Electroneutrality condition ……………………..……………………..…………………… 19 I.3.2.2. Stoichiometric condition ……………………..……………………..…………………….... 19 3.3. Classification of piezoelectric ceramics ……………………..……………………..……….... 20 I.3.3.1. Barium Titanate BaTiO3 ……………………..……………………..…………………….... 20 I.3.3.2. Lead Titanate PbTiO3 ……………………..……………………..……………………..…... 20 I.3.3.3. Lead zirconate PbZrO3 ……………………..……………………..………………………... 21 I.3.3.4. Lead Zirconate Titanate PZT ……………………..……………………..………………..... 21 I.3.4. Phase diagram of solid solutions of Pb(Zrx,Ti1-x)O3 ……………………..…………………..... 21 I.4. Effect of doping on piezoelectric properties ……………………..……………………..……..... 23 I.4.1 Doping of PZT ……………………..……………………..……………………..…………..... 23 I.4.2. Classification of dopants ……………………..……………………..………………………... 24 I.4.2.1. Substitution with an isovalent dopant (with a valency equal to that of the substituted ion) .. 24 I.4.2.2. Substitution by an acceptor dopant whose valency is lower than that of the site it replaces…. 24 I.4.2.3. Substitution by an ion with a higher valency than the substituted ion ………………………. 24 I.5. Applications of piezoelectric materials ……………………..……………………..………….... 26 I.6. Previous works ……………………..……………………..……………………………………. 26 Bibliographic References ……………………..……………………..……………………..………. 27 1. Introduction …………………………………………………………………………………… 30 II.2. Ceramic method ……………………………………………………………………………….. 30 II.3. Experimental procedure ……………………………………………………………………….. 31 II.3.1. Starting products …………………………………………………………………………….. 31 II.3.1.1. Basic products …………………………………………………………………………….. 32 II.3.1.2. Dopants ……………………………………………………………………………………. 33 II.3.2. Sample preparation method …………………………………………………………………. 35 II.3.2.1. Weighing and stirring ……………………………………………………………………... 37 II.3.2.2. Oven drying ……………………………………………………………………………….. 37 II.3.2.3. Grinding …………………………………………………………………………………... 38 II.3.2.4. Calcination ………………………………………………………………………………... 38 II.3.2.5. Regrinding ………………………………………………………………………………… 39 II.3.2.6. Formatting ………………………………………………………………………………… 39 II.3.2.7. Sintering …………………………………………………………………………………... 40 II.4. Experimental characterization techniques: Analysis and equipment ………………………….. 42 II.4.1. Measuring density (d) ……………………………………………………………………….. 42 II.4.2. Measuring porosity (P) ……………………………………………………………………… 43 II.4.3. Crystal structure analysis by XRD …………………………………………………………... 44 II.4.4. Infrared spectroscopy (IR) …………………………………………………………………... 46 II.4.5. SEM analysis ………………………………………………………………………………... 48 Bibliographic References ……………………..……………………..……………………..………. 49 II.1. Introduction …………………………………………………………………………………... 51 III.2. Ceramics synthesis and production …………………………………………………………... 51 III.3. Study of the stability criteria of the perovskite structure ……………………………………… 52 III.4. Morphological study of PCZT-FZS ceramics ………………………………………………… 54 III.4.1. Density ……………………………………………………………………………………... 55 III.4.2. Porosity …………………………………………………………………………………….. 57 III.5. Microstructure ………………………………………………………………………………... 58 III.5.1. Structural study of PCZT-FZS ……………………………………………………………… 58 III.5.2. Scanning electron microscopy (SEM) characterization …………………………………….. 65 III.5.3. Phase analysis by infrared spectrometry (IR) ………………………………………………. 67 Bibliographic References ……………………..……………………..……………………..………. 69 General Conclusion ……………………..……………………..…………………………………… 71 |
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