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The dielectric behaviour of the most famous piezoelectric material, Pb(Zr0.52Ti0.48)O3 ceramics, below room temperature is explained by the topology of the sample, and not by intrinsic structural changes. The dielectric anomaly found below room temperature has purely extrinsic origin and it is related to two excitations in the GHz range: piezoelectric resonances in grains (PR) with nearly temperature independent frequency and domain wall oscillations (DW) that slows down towards ~ 270 K.
Description
Figure:
(a) Temperature dependence of the frequencies of the MW and THz excitations of PZT 52/48,
(b) their contributions to the permittivity together with the permittivity measured at 100 kHz,
(c) micrograph of the PZT ceramics, showing grain boundaries and domains, and
(d) complex dielectric spectra of PZT 52/48 in the high-frequency and THz ranges.