R-curve behavior of BaTiO3- and PZT ceramics under the influence of an electric field applied parallel to the crack front

The fracture resistance curves (R-curves) of BaTiO3 and commercial PZT-PIC 151 were measured with compact tension specimens under the influence of an electric field applied parallel to the crack front. A strong influence of t he electric field on the starting and plateau value was found as well as on the length of the R-curve, Generally a toughness increase was detected wit h increasing electric field. The toughening effect is estimated from the ch ange in crack tip stress intensity induced by ferroelastic domain switching near the crack tip using the weight function formalism developed for stres s-induced transformation toughening of zirconia ceramics. In order to obtai n a quantitative prediction of toughening, ferroelastic and ferroelectric p roperties were measured, (C) 2000 Acta Metallurgica Inc. Published by Elsev ier Science Ltd. All rights reserved