Dielectric relaxation and conductivity behavior in modified lead titanate ferroelectric ceramics

Abstract

The frequency and temperature dielectric response and the electrical conductivity behavior around the ferroelectric-paraelectric phase transition temperature are studied in the ferroelectric ceramic system (Pb 0.88 Sm 0.08 )(Ti 1−x Mn x )O 3 , with x = 0, 1, 3 at.%. The contribution of the conductive processes to the dielectric relaxation for the studied frequency range is discussed considering the oxygen vacancies as the most mobile ionic defects in perovskites, whose concentration seems to increase with the manganese content. The relaxation processes below the transition temperature are associated with the decay of the polarization in the oxygen-defect-related dipoles due to their hopping conduction. Above the ferroelectric-paraelectric phase transition temperature, the electrical conduction is governed by the thermal excitation of carriers from oxygen vacancies; the relaxation processes are associated with ionic dipoles distorted by the oxygen vacancies.

Structure, dielectric and impedance properties of BaTiO3–Bi(Y0.5Yb0.5)O3 lead-free ceramics

“…E a is the activation energy of the conduction. Values in the ranges 0.3-0.4 and 0.6-1.3 eV in the low temperature region 200-400°C have been associated with singly and doubly ionized oxygen vacancies, respectively [33]. In the high temperature region, mixed conduction governed by both doubly ionized oxygen and lead vacancies for F and Mn co-doped PZT Fig.…”

“…Inset shows temperature dependence of relaxation frequency [35] is responsible for the high activation energy of 1.47-2.02 eV. It is reported [33] that the activation energy in the ABO 3 perovskite structure decreases with increasing oxygen vacancy content. For the studied samples, The bulk activation energy decreases with the BYYb content for x [ 0.02, which suggests an increase of oxygen vacancy concentration.…”

“…Figure 10 The hopping processes could be associated with relaxations involving thermal motions of titanium ions (Ti 4? ) [33]. Thus The relaxation process may not only be associated with oxygen vacancies relaxation but also related to thermal motions of titanium ions (Ti 4? )…”

“…The relaxation activation energies are about 1.2-2.2 eV. It is reported[33] that the activation energies of the hopping frequencies of the carriers is about 1.7-2.1 eV for (Pb 0.88 Sm 0.08 ) (Ti 1-x Mn x )O 3 ceramics above T m at low frequencies.…”

Investigation of the conduction processes in PZT‐based multiferroics: Analysis from Jonscher's formalism

“…The second mechanism found for the BaM005 composition in region II, with an activation energy value around 0.53 eV, is related to superexchange interactions of Fe 3+ –O 2− –Fe 3+ type, similarly to that observed for the BaM004 composition and previously discussed. The third conduction process observed in the BaM005 composition for temperatures far above the T C (region III), with activation energies around 1.98 eV, can be related to relaxation mechanisms involving thermal motions of Ti 4+ ions on the B‐site of the perovskite structure . In this way, the Ti 4+ (and Zr 4+ ) ions start to show a hopping frequency in this temperature range, which is not a common behavior in pure PZT systems.…”