Stress effects in two modified lead zirconate titanate ferroelectric ceramics

Abstract

Mechanical properties of ferroelectric ceramics with compositions Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 and Pb0.97La0.02(Zr0.92Ti0.08)O3 have been studied as functions of both hydrostatic pressure and uniaxial stress. Measurements of ultrasonic velocity and sample strains have been made in order to characterize unpoled samples. Both materials have pressure-induced ferroelectric (FE) to antiferroelectric (AFE) phase transitions at ∼0.2 GPa of hydrostatic pressure. Under uniaxial-stress conditions two effects are observed: rotation of FE domains and the FE–AFE phase transition. These effects are separately resolved by the measurements, even though they occur in overlapping stress regions. The domain reorientation responses of the two materials appear to be nearly identical, but the FE–AFE transition begins at lower stress levels for the Nb-doped material. This is presumably due to that material transforming into the orthorhombic (PbZrO3) phase, whereas the La-doped material transforms into the tetragonal AFE phase. The phase transition is spread over a broad range of uniaxial stress for each material and is not nearly complete by 0.6 GPa, the highest stress level attainable. Possible implications of the results for shock-wave studies of FE ceramics are briefly discussed.