HARMONIC-ANALYSIS OF THE POLARIZATION RESPONSE IN PB(MG1 3NB2/3)O-3-BASED CERAMICS - A STUDY IN AGING/

The polarization response of a ferroelectric ceramic displays nonlinea r behavior at high applied fields due to saturation effects. Weak-fiel d dielectric aging imposes additional nonlinearity on the hysteresis l oops of these materials. Harmonic analysis using a discrete Fourier tr ansform (DFT) permitted an observation of the change in the polarizati on frequency spectrum as Pb(Mg1/3Nb2/3)O-3-based relaxor ceramics aged . It also facilitated the calculation of ac current, power, and ''inte rnal bias field''. The results show that particular harmonics in the p olarization signal are sensitive indications of aging behavior. The av erage power dissipated at weak ac fields was found to decrease with ag ing time; and the power dissipated at strong fields tended to increase .