FRACTURE-TOUGHNESS ANISOTROPY OF PZT

Fracture toughness of a lead zirconate titanate (PZT) piezoelectric wa s measured using the indentation technique and the single edge notch b end (SENB) method. Values of fracture toughness, K-Ic, show significan t anisotropy in poled samples, with longest and shortest crack lengths in the directions parallel and perpendicular to the poling axis, resp ectively. The crack profiles below the indented surfaces have been stu died for both the unpoled and the poled samples. This also revealed th e shape and size of the plastically deformed zone underneath the inden tation. The microstructural anisotropy and internal stresses caused by the poling, and the contribution of stresses introduced by the experi mental method are considered in the discussion. (C) 1997 Elsevier Scie nce S.A.