Abstract: The authors investigate the effects of piezoelectric hysteresis and relaxation induced by a weak constant electric field in ferroelectric ceramics. Piezoelectric resonance is analyzed to make precision measurements of impedance spectra for thickness and radial vibrations of thin piezoceramic disks at different polarities of the applied constant electric field and polarization of the piezoceramic. A study is performed of the field and temporal dependences of the complex piezoelectric constants of piezoceramics, obtained by processing sequentially measured impedance spectra A physical interpretation of the results is proposed. © 2023, Allerton Press, Inc.