Microstructures, piezoelectric properties and energy harvesting performance of undoped (K0.5Na0.5)NbO3 lead-free ceramics fabricated via two-step sintering

Research output: Contribution to journalArticlepeer-review

Authors

Colleges, School and Institutes

External organisations

  • University of Birmingham

Abstract

Piezoelectric energy harvesters have become increasingly popular in the field of green energy because of the ability to convert low-frequency environmental vibrations into usable electricity. To fabricate high-performance energy harvesters, the key requirements are piezoelectric ceramics with a small grain size, of near-full density, the intended stoichiometric ratio and a high transduction coefficient. In this work, the effects of two-step sintering on the sinterability, microstructure, piezoelectric properties and energy harvesting performance of (K0.5Na0.5)NbO3 were systematically investigated. Compared with conventional single-step sintering, two-step sintering samples were of higher density, increasing from 91 % to 95 % of theoretical, reduced mean grain size, down from 17 μm to 7.5 μm, and decreased evaporation of the alkali metals. This translated into an improved piezoelectric performance (d33 ∼122 pC/N, kp ∼36 % and Qm ∼76), a higher transduction coefficient and energy conversion efficiency as well as a higher open-circuit voltage and power density. This demonstrates the potential of two-step sintering as a high through-put sintering technique for moderate-performance, pure KNN ceramics.

Bibliographic note

Funding Information: The work was supported by grants from the UK's Engineering and Physical Science Research Council ‘Multi scale tuning of interfaces and surfaces for energy applications’, grant number EP/P007821/1 and School of Metallurgy and Materials, University of Birmingham . The authors also appreciate the contributions from Dr. Daniel Reed, Dr. Vinothini Venkatachalam, Mr. Carl Meggs and Mr. Paul Stanley from the University of Birmingham, also Prof. Mike Reece from the Queen Mary University of London for assistance. Funding Information: The work was supported by grants from the UK's Engineering and Physical Science Research Council ?Multi scale tuning of interfaces and surfaces for energy applications?, grant number EP/P007821/1 and School of Metallurgy and Materials, University of Birmingham. The authors also appreciate the contributions from Dr. Daniel Reed, Dr. Vinothini Venkatachalam, Mr. Carl Meggs and Mr. Paul Stanley from the University of Birmingham, also Prof. Mike Reece from the Queen Mary University of London for assistance. Publisher Copyright: © 2020 Elsevier Ltd Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

Details

Original languageEnglish
Pages (from-to)2977-2988
Number of pages12
JournalJournal of the European Ceramic Society
Volume40
Issue number8
Publication statusPublished - Jul 2020

Keywords

  • Density, Grain size, Potassium sodium niobate (KNaNbO), Sintering kinetics, Two-step sintering