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http://cicese.repositorioinstitucional.mx/jspui/handle/1007/2231| Caracterización estructural y dieléctrica del cerámico Bi4Ti3O12 dopado con praseodimio y europio Structural and dialectric characterization of Bi4Ti3O12 ceramics doped with praseodimium and europium. | |
| Abril Munro Rojas | |
| Jorge Octavio Mata Ramírez | |
| Acceso Abierto | |
| Atribución | |
| Ferroelectricidad, estructura tipo aurivillius, mecanismos de conducción, ferroelectrics, aurivillius structure, conduction mechanism | |
| Se prepararon muestras de los sistemas cerámicos Bi4Ti3O12, dopando con diferentes concentraciones de praseodimio (Pr) y europio (Eu) en el sitio A(sitio del bismuto) y vanadio (V) en el sitio B(sitio del titanio). Se realizaron estudios cristalográficos y morfológicos empleando DRX y SEM. Se observaron diferencias en la micro-estructura, las características cristalográficas, densidad y tamaño de grano como función del contenido de Pr, Eu y V. Posteriormente se efectuaron medidas de constante dieléctrica y pérdidas dieléctricas como función de temperatura, en barridos desde temperatura ambiente (TA) hasta 750°C, a diferentes frecuencias y para cada una de las combinaciones. Estos estudios demuestran que la presencia de tierras raras disminuye notablemente la temperatura de transición e incrementa notablemente los valores de la constante dieléctrica. The stoichiometric Bi4Ti3O12 ceramic system was obtained doped with different concentrations of Pr and Eu ions in site A (Bi) and Vanadium in B (Ti) sites. Crystallographic and surface morphological studies were carried out by the DRX and SEM techniques. Differences in the microstructure, Crystallographic features, densities and grain size were observed as functions of Pr3+,4+, Eu3+ and V3+,5+ contents. Measurements of dielectric constant and dielectric loss were made as functions of temperature from room temperature (RT) to 750 “C, at different frequency values. This study shows that rare earth presence in the structure modifies the transition temperature Tc and dramatically increases the dielectric constant values. The results lead us to study the frequency response by means of the analysis of the complex impedance. In order to explain the local and non-local conduction processes that provoke the disruption of the long-range ferroelectric order by clamping effects. of the domain walls due to the thermally activated diffusion of oxygen vacancies. The relaxation processes are very much conditioned by the grain and domain sizes, the degree of deformation of the lattice and the crystallites, as well as the potential barriers at the grain boundaries. Values of the activation energy corresponding to the different relaxation processes were determined from an Arrhenius law fitting of experimental data, identifying thus the involved mechanisms in excellent agreement with those obtained from the temperature response. Well defined BIT nanostructures produced as a consequence of the synthesis method were observed. | |
| CICESE | |
| 2007 | |
| Tesis de maestría | |
| Español | |
| Munro Rojas, A.2007.Caracterización estructural y dieléctrica del cerámico Bi4Ti3O12 dopado con praseodimio y europio.Tesis de Maestría en Ciencias.Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California. 153p. | |
| OTRAS ESPECIALIDADES FÍSICAS | |
| Aparece en las colecciones: | Tesis - Física de Materiales |
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