resumo
The considerable decrease in temperature and time makes FLASH sintering a more sustainable alternative for materials processing. FLASH also becomes relevant if volatile elements are part of the material to be processed, as in alkali-based piezoelectrics like the promising lead-free K0.5Na0.5NbO3 (KNN). Due to the volatile nature of K and Na, KNN is difficult to process by conventional sintering. Although some studies have been undertaken, much remains to be understood to properly engineer the FLASH sintering process of KNN. In this work, the effect of FLASH temperature, T-F, is studied as a function of the particle size and impurity content of KNN powders. Differences are demonstrated: while the particle size and impurity degree markedly influence T-F, they do not significantly affect the densification and grain growth processes. The conductivity of KNN FLASH-sintered ceramics and KNN single crystals (SCs) is compared to elucidate the role of particles' surface conduction. When particles' surfaces are not present, as in the case of SCs, the FLASH process requires higher temperatures and conductivity values. These results have implications in understanding FLASH sintering towards a more sustainable processing of lead-free piezoelectrics.
categoria
Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Physics, Applied; Physics, Condensed Matter
autores
Serrazina, R; Ribeiro, C; Costa, ME; Pereira, L; Vilarinho, PM; Senos, AMOR
nossos autores
Ana Maria de Oliveira e Rocha Senos
Colaborador
Camila Alves Ribeiro
Estudante de doutoramento
Maria Elisabete Jorge Vieira Costa
Colaborador
Paula Maria Lousada Silveirinha Vilarinho
Vice-Diretor
Ricardo Serrazina
Estudante de doutoramentoProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
agradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MEC and when appropriate, co-financed by FEDER under the PT2020 Partnership Agreement. This work was also financed by Portugal 2020 through European Regional Development Fund (ERDF), in the frame of Operational Competitiveness and Internationalization Programme (POCI), in the scope of the project FLASH sintering of lead-free functional oxides towards sustainable processing of materials for energy and related applications-FLASH, POCI-01-0247-FEDER-029078. Ricardo Serrazina acknowledges FCT for financial support (SFRH/PD/BD/128411/2017).