Far from equilibrium pulsed poled Mn-doped relaxor ferroelectrics: a positive aging relaxation process

The aging behavior of high temperature pulse poled (HTPP) Mn-doped relaxor ferroelectrics (RFE) was investigated. It was found that following HTPP, a far from equilibrium state can be realized. Within this state, the dielectric and piezoelectric properties increased with aging in both single crystal and textured ceramic materials. The degree of aging, as well as the time scales involved, surpassed previous aging studies. The single crystals experienced 40–60 % increases in d₃₃ and ε_r over the span of a month, and the textured ceramics experienced 15–20 % increases over multiple weeks. Changes in Rayleigh analysis, heat flow at phase transitions, and X-ray diffraction patterns pointed towards important intrinsic transformations in the systems induced by HTPP and positive aging. It is hypothesized that such a transformation can arise due to far from equilibrium conditions driven by the ultra-fast field switching of pulse poling. The resultant uncompensated depolarization field that forms from ineffective bulk screening depressed properties on day one. With time, the defect dipoles within the Mn-doped systems are assumed to align to generate an internal field counteracting the incomplete compensation of the depolarization field as evidenced by the asymmetric hysteresis loops. The pulse poled state and the associated positive aging properties were analyzed under a first order elastic Gibbs Landau-Devonshire Theory and other phenomenological descriptions of the physical properties. The HTPP induced internal electric field and electrostrictive coupling lead to the time dependent evolution of the first order ferroelectric character and piezoelectric property enhancement.