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# The synthesis and characterisation of lead-free piezoelectric ceramics

Roberts, William Michael (2012)
M.Res. thesis, University of Birmingham.

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## Abstract

With a growing awareness of the environmental and health hazards of lead, there has been renewed interest in developing lead-free alternatives to lead zirconate titanate (PZT), which currently dominates the market for piezoelectric materials. Some of the most promising lead-free piezoelectric materials are those based on potassium sodium niobate (KNN). This project involved the fabrication and characterisation of lithium-doped KNN ceramic, which has been reported to show excellent piezoelectric properties. Samples containing 0-9 mol% Li were synthesised by a conventional mixed oxide method, before their key functional properties were analysed. The addition of lithium was found to promote grain growth within the microstructure, resulting in a denser ceramic. A phase transformation from the orthorhombic to tetragonal crystal structure was also identified. Optimum piezoelectric properties were observed in KNN samples containing 7 mol% Li (k$$_p$$=0.33, k$$_t$$=0.37, d$$_{33}$$=126 pC/N). Further optimisation of the fabrication route and continued investigation into the most effective dopants could potentially bring KNN on a par with many commercial lead-based ceramics.

Type of Work: M.Res. thesis. Button, Tim W Colleges (2008 onwards) > College of Engineering & Physical Sciences Department of Metallurgy and Materials, School of Engineering TN Mining engineering. MetallurgyTP Chemical technologyTS Manufactures University of Birmingham 3442
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