title: Electric field-induced strain behavior in lithium- and copper-added potassium sodium niobate piezoceramics and 1-3 piezocomposites.
abstract: Potassium sodium niobate (KNN)-based leadfree materials were prepared and their field-induced strain behaviors were investigated. Ceramic lead-free piezoelectric materials were prepared in bulk and fiber forms with 1 mol% CuO-added potassium sodium niobate K0.5Na0.5NbO3 and x = 7 mol% lithium-modified (K(0.5-x/2)Na(0.5-x/2)Li(x))NbO(3) compositions. Fibers were drawn using a novel alginate gelation technique. Piezocomposites were prepared from these fibers with 1-3 connectivity and an epoxy matrix. A fully recoverable electrostrain of up to approximately 0.11% was observed in the CuO-added sample, whereas the Li-modified sample yielded up to 0.10% at 50 kV/cm electric field. A strain value of up to approximately 0.03% at 50 kV/cm electric field was obtained for piezocomposites prepared from lithium-modified fibers. The high-field converse piezoelectric coefficient was calculated from the strain-electric field (x-E) graph for all samples. Strain characteristics of the bulk and piezocomposite samples were analyzed based on the variation of strain with respect to square of the polarization (x-P2) to determine the electrostrictive contribution to the strain.
authors.affiliation: Maltepe University, Faculty of Engineering, Maltepe, Istanbul, Turkey. ebrualkoy@maltepe.edu.tr
authors.forename: Ebru Mensur
authors.initials: EM
authors.lastname: Alkoy
authors.forename: Ayse
authors.initials: A
authors.lastname: Berksoy
authors.forename: A Serkan
authors.initials: AS
authors.lastname: Tekdas