Flash sintering of high-performance lead-free (K,Na)NbO3-based piezoceramics: microstructure-properties relationship
Piezoelectric materials are widely used as functional element of electromechanical trans- ducers in a large number of domestic and industrial applications. Because of their low cost and relatively easy fabrication, piezoelectric transducers are mainly based on polycrys- talline ferroelectric oxides;...
| Autor: | |
|---|---|
| Formato: | tesis de maestría |
| Fecha de publicación: | 2023 |
| País: | España |
| Recursos: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/400235 |
| Acesso em linha: | https://hdl.handle.net/2117/400235 |
| Access Level: | acceso abierto |
| Palavra-chave: | Piezoelectric ceramics Microstructure Flash sintering KNN piezoceramic microstructure highly-dense sample applied field current density dwelling time grain size dielectric ferroelectric Ceràmica piezoelèctrica Microestructura Àrees temàtiques de la UPC::Física::Termodinàmica::Canvis d'estat |
| Resumo: | Piezoelectric materials are widely used as functional element of electromechanical trans- ducers in a large number of domestic and industrial applications. Because of their low cost and relatively easy fabrication, piezoelectric transducers are mainly based on polycrys- talline ferroelectric oxides; that is, oxide-based ferroelectric ceramics. Although piezoelec- tric ceramics are extensively used, their fabrication entails two environmental issue. On the one hand, the most used piezoelectric materials contain toxic element, in particular a high lead content. On the other hand, the ceramic materials manufacture requires a high energy demand, since the heat treatments involve high temperatures, in general above 1200 ºC, for several hours. To solve these issues, new eco-friendly piezoelectric materials are required. In this context, this project focusses on obtained lead-free piezoceramics by a low cost fast sintering process. In particular, this project aims to obtain lead-free (K, Na)NbO3-based piezoceramics with tailored microstructure to show high electrome- chanical response. Flash sintering, a novel ultrafast sintering technique, will be used to obtain dense ceramics of (K, Na)NbO3 system. This sintering methodology leads to a higher control of the microstructure and, therefore, enhanced functional properties may be reached. Controlling the flash sintering parameters (i.e., applied electric field, electrical current density and dwelling time) is crucial for obtaining high-dense samples and, consequently, it has an influence in the microstructure and the functional properties, which is what this project studies. In this work, highly-dense KNL-NTS ceramics are obtained by current controled flash sintering. The results reveal a grain growth for a decreasing applied field and decreasing dwelling time, but the opposite for the current density. Moreover, regarding functional properties, the highest remnant polarization is obtained for the sample with the highest dielectric constant and the smallest grain size. |
|---|