abstract
Direct current electrical poling of textured hydroxyapatite (HAp) ceramics is reported here to exhibit weak ferroelectricity and pyroelectricity, but a remarkably higher (six orders of magnitude) piezoelectricity. The piezoelectric strain coefficient is an order higher than that of bone and of the same order as that of quartz crystal and uncalcified collagen in tendon. The piezoelectric charge coefficient is an order higher than bone, and three orders higher than that of tendon. Piezoelectric constants of poled HAp ceramics are high enough to have physiological relevance such as in the use of bone grafts for stimulated calcification or in energy harvesting from physiological motions. Piezoelectricity in these ceramics can be tuned by controlling texture, and poling parameters. The density of power that can be harvested from HAp ceramics is currently just one order lower than biocompatible ferroelectric ceramic such as barium titanate.
keywords
TEMPLATED GRAIN-GROWTH; BONE; DENSIFICATION
subject category
Materials Science
authors
Gandhi, AA; Wojtas, M; Lang, SB; Kholkin, AL; Tofail, SAM
our authors
Andrei Kholkin
Principal Researcher
Maciej Wojtas
Post-doc Fellowshipacknowledgements
The authors wish to acknowledge the Higher Education Authority, Ireland for a generous Laboratory Refurbishment Grant in 2008 that enabled the purchase of a Spark Plasma Sintering machine. Maciek Wojtas would like to acknowledge the support of a research fellowship from the Polish Ministry of Science and Higher Education, grant no. 657/MOB/2011/0.