The Role of Particle Contact in Densification of FLASH Sintered Potassium Sodium Niobate


Potassium sodium niobate, K0.5Na0.5NbO3(KNN) is a lead-free piezoelectric with the potential to replace lead zirconate titanate (PZT) in electromechanical applications. Due to its cuboid particle morphology and volatile elements, monophasic and dense ceramics are difficult to obtain via conventional sintering. In this work, isothermal FLASH sintering produced uniformly densified KNN ceramics at 900 degrees C, 200 degrees C lower than conventional sintering. Specific surface area (SSA) analysis ofpre-FLASHceramics revealed that a 30 min isothermal hold at 900 degrees C, before the application of electric field, increased the contact area between particles and was crucial to promote uniform densification. Finite element modelling (FEM) revealed why density is more uniform when using isothermal heating compared with a constant heating rate, commonly used in FLASH sintering. These results extend our understanding of FLASH sintering and illustrate its relevance for the development of lead-free piezoelectrics.



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Serrazina, R; Senos, AMOR; Pereira, L; Dean, JS; Reaney, IM; Vilarinho, PM

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This work was also developed within the scope of the project CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES. 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).

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