Time dependent dc resistance degradation in lead-based perovskites: 0.7 Pb(Mg1/3Nb2/3)O3−0.3 PbTiO3

Abstract

Highly accelerated lifetime tests (HALTs), thermally stimulated depolarization current (TSDC), and impedance spectroscopy (IS) measurements were performed on 0.7 Pb(Mg1/3Nb2/3)O3−0.3 PbTiO3 (PMN-PT) single crystal to investigate time dependent dc resistance degradation under a dc bias. A low activation energy of 0.61±0.04 eV which controls the degradation process in PMN-PT single crystal is determined from the characteristic degradation time tC in HALT. Meanwhile, in a complementary TSDC investigation, a broad depolarization peak with an activation energy of 0.6±0.03 eV is observed in virgin PMN-PT single crystal having the characteristics of ionic space charge. Finally, impedance spectra of degraded PMN-PT single crystal exhibited three relaxations in contrast to two relaxations in virgin PMN-PT single crystal. In terms of equivalent circuit, an element combination R-ZCPE corresponding to ionic conduction is common to both virgin and degraded single crystals, and an activation energy about 0.64 eV, attributed to the ionic transport, is also obtained. This value is low compared to similar studies on alkaline-earth titanate perovskites, such as Fe-doped SrTiO3, however, here we suggest the activation energy about 0.6 eV from three independent measurements is attributed to the migration of oxygen vacancies in this particular lead-based single crystal, and besides this apparent ionic conduction, band electronic conduction is also discussed in both virgin and degraded single crystals in this paper.

Accelerated domain switching speed in single-crystal LiNbO3 thin films

“…This empirical equation is very successful in description of resistance degradation in most perovskite oxides (the analytic physical formula is still missing at present). [27][28][29][30] As t > t 0 (domain switching is completed), the field across R i drops quickly to stop the Schottky emission. At this moment, the pure capacitor charging current dominates the whole process with the form of…”

“…4(a), we assume that I i under E is time dependent, as proved in most dielectrics. [27][28][29] Initially, I i is low after capacitor charging time, and E is fully dropped across the film. But, after a characteristic time of s d when the resistance degradation across the non-ferroelectric layer occurs, I i increases abruptly in 2-3 orders of magnitude until to saturate at a constant value.…”

A-site stoichiometry and piezoelectric response in thin film PbZr1−xTixO3

“…In bulk PZT, Prisedsky et al determined that lead vacancies are compensated by oxygen vacancies and holes. [13][14][15] A more general understanding of ionic defects and charge carriers in PZT films should lead to an improved understanding of breakdown and aging characteristics. 14,16 Point defects produce local electric and elastic fields.…”

Resistance variation in donor-doped PZT stacks with Cu inner electrodes under high field stress

“…Then the issue of high field conductivity variations in PZT has to be re-considered and phenomena similar to stoichiometry polarization in SrTiO 3 (see above) would hardly be surprising. Little data is available on conductivity variations in bulk samples of lead based perovskites under field at or above 200°C [33]. More information can be found on ferroelectric thin films (see e.g.…”

“…Such a detailed understanding is not available for many other perovskite-type electroceramics. For example, it is still far from being quantified under which doping, pressure and temperature conditions ionic or electronic conduction prevails in PZT and related materials [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45], and also to what extent grain boundaries are either highly resistive or represent highly conductive paths for charge transport. Only recently, it was shown that in donor-doped PZT very pronounced oxygen tracer diffusion along grain boundaries may take place [46,47].…”