Peculiarities of Pyroelectric Resonance–Antiresonance Phenomena in PZT Ceramics
The pyroelectric characteristics of lead–zirconate–titanate (PZT) ceramics of composition near the morphotropic phase boundary were studied by the photothermomodulation method. The frequency spectra of the amplitude and phase of pyroelectric response in the current and voltage modes were transformed into thermowave profiles. The asymmetry of thickness profiles of the pyroactivity distribution and its reversal under reversing poling voltage polarity were revealed. Attention has been concentrated on elucidation of the peculiarities of pyroelectric resonance–antiresonance (PyRAR) and inverse antiresonance–resonance (PyARR) sequences observed in the 25–35 kHz range thermowave excitation of flexural mode thermomechanical vibrations induced by periodical thermal stresses in the undersurface layer of PZT disks. External voltage-controllable reversible inversion of the sequence PyRAR to PyARR under IR-beam probing of the opposite disk sides, being at different polarities of poling voltage, was found. The connection between poling voltage polarity, the shape of the thermowave profile of pyroelectric parameters, and the inversion of Py (RAR–ARR) sequence were ascertained. The results are compared with those observed earlier for edge-fixed PVDF and P(VDF/TrFE) copolymer films and discussed in regard to highly sensitive pyroelectric detectors.
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