The temperature dependence of the dynamic pyroelectric coefficient at the s
inusoidal thermal flow (f = 2.5; 10 and 800 Hz), the discharge currents and
the dielectric permittivity (f = 1 kHz) for three groups of the low-coerci
ve materials was studied. These materials-belong:to the multicomponent PZT-
based systems modified with certain additives and have the Curie temperatur
es 215, 280 and 320 degrees C (compositions 1, 2, 3). It has been establish
ed that in the process of heating the sample, in the region of the transiti
on into a paraelectric phase the dynamic pyroelectric coefficient passes th
rough two maxima between which the difference of temperatures is 27.5; 25 a
nd 6 degrees C for compositions 1, 2, 3, respectively. The maxima of discha
rge currents and the anomalies in the temperature dependence of the dielect
ronic permittivity correspond to these maxima. A partial depolarization of
the samples in the region of a low-temperature:maximum of the pyroelectric
coefficient and the discharge current is due to the release of a space char
ge and the increase of mobility of the domain boundaries in the vicinity of
the morphotropic phase transition.