(K, Na)Nbo 3 Lead-Free Piezoceramics Prepared by Microwave Sintering and Solvothermal Powder Synthesis
17 Pages Posted: 23 Apr 2022
Abstract
Low temperature and short processing time are benefical for fabricating (K, Na)NbO 3 (KNN) lead-free piezoelectric ceramics with a drawback of easy alkali metal volatilization during the powder synthesis and sintering processes. This study revealed that microwave sintering in addition to microwave solvothermal powder synthesis can lead to short-time fabrication of KNN ceramics with high density and fine grains. It was found that KNN powder with a single perovskite structure can be synthesized successfully by microwave solvothermal method if the KOH/NaOH concentration exceeds 1 M, which can be densified by microwave sintering to a high relative density close to 97% at 1050 o C even using 2/9 shorter soak time than normal sintering at the same temperature. Importantly, the microwave-sintered KNN ceramics show better piezoelectric and ferroelectric properties than that by normal sintering. Despite nonexistence of any dopants, a high-level piezoelectric coefficient ( d 33 ) reaching 132 pC/N was obtained in the MS-processed pure KNN ceramics that also possess better ferroelectric properties with a high remnant polarization ( P r ) up to 26.3 µC/cm 2 . The present work indicate that the microwave solvothermal method is a promising method for preparing KNN-based ceramics.
Keywords: Potassium sodium niobate, Lead-free piezoelectric ceramics, Microwave solvothermal synthesis, Microwave sintering
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