abstract
Piezoelectricity, the linear relationship between stress and induced electrical charge, has attracted recent interest due to its manifestation in biological molecules such as synthetic polypeptides or amino acid crystals, including gamma (gamma) glycine. It has also been demonstrated in bone, collagen, elastin and the synthetic bone mineral hydroxyapatite. Piezoelectric coeffcients exhibited by these biological materials are generally low, typically in the range of 0.1-10 pmV(-1), limiting technological applications. Guided by quantum mechanical calculations we have measured a high shear piezoelectricity (178 pmV(-1)) in the amino acid crystal beta (beta) glycine, which is of similar magnitude to barium titanate or lead zirconate titanate. Our calculations show that the high piezoelectric coeffcients originate from an effcient packing of the molecules along certain crystallographic planes and directions. The highest predicted piezoelectric voltage constant for beta-glycine crystals is 8VmN(-1), which is an order of magnitude larger than the voltage generated by any currently used ceramic or polymer.
keywords
CRYSTAL-STRUCTURE; DIELECTRIC-PROPERTIES; BETA-GLYCINE; CRYSTALLIZATION; TRANSFORMATION; PEPTIDE; GROWTH; FILMS
subject category
Chemistry; Materials Science; Physics
authors
Guerin, S; Stapleton, A; Chovan, D; Mouras, R; Gleeson, M; McKeown, C; Noor, MR; Silien, C; Rhen, FMF; Kholkin, AL; Liu, N; Soulimane, T; Tofail, SAM; Thompson, D
our authors
acknowledgements
The authors thank E. O'Connell, A. Stewart and U. Bangert for use of their optical microscope. This publication has emanated from research conducted with the financial support of Science Foundation Ireland (SFI) and is co-funded under the European Regional Development Fund under Grant Number 13/RC/2073. D.T. acknowledges support from SFI under Grant Number 15/CDA/3491, and for provision of computing resources at the SFI/Higher Education Authority Irish Center for High-End Computing (ICHEC). A.L.K. acknowledges support from CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. Funding from the Irish Research Council EMBARK Postgraduate Scholarship (RS/2012/337) to A.S. is acknowledged. S.A.M.T. acknowledges Enterprise Ireland and Erasmus for their long-standing support and funding.