Electrostriction versus low frequency dielectric dispersion in PbZrO3 and PbHfO3 single crystals

For the antiferroelectric crystals PbZrO3 and PbHfO3 pure and doped with sm all amount of PbTiO3 the measurements of electrostrictive strain e have bee n performed in paraelectric phase as a function of temperature, frequency ( 40-400 Hz) and strength (100-700 kV/m) of an applied electric field. In par ticular, compliance with quadratic relation between strain e and the electr ic field E (e = ME2) in different frequency regions was examined. The obser ved effects for PbZrO3 and PbHfO3 were compared and discussed with previous ly investigated low frequency dielectric dispersion found in those antiferr oelectric materials. The experiments showed that in the frequency range whe re the dipolar relaxation exists, the departure from the quadratic relation (e = ME2) can be clearly observed for PbZrO3 and PZT single crystals. In a ll investigated single crystals (PbZrO3, PZT and PbHfO3) the dependence of strain versus electric field obeys the electrostrictive relation in the fre quency range below and above dielectric relaxation observed. For frequencie s beyond dielectric dispersion the electrostrictive coefficients Q(11) for all samples are temperature independent and take values typical for ferroel ectric and antiferroelectric materials (i.e. Q(11) congruent to 2 x 10(-2) - 3 x 10(-2) m(4)/C-2). (C) 2001 Kluwer Academic Publishers.