Impedance spectroscopy study of a compositionally graded lead zirconate titanate structure

Abstract

The dielectric response of a compositionally graded lead zirconate titanate (PZT) structure prepared by pulsed laser deposition was studied as a function of frequency and temperature (from room temperature up to 419 °C) using impedance spectroscopy. The analysis of combined impedance and modulus spectroscopy, as well as complex plane plots, revealed that the bulk grain relaxation was the dominant relaxation process over the frequency and temperature range studied. The calculated bulk grain capacitance of the graded structure shows an anomalous behavior near temperatures related to the phase transition temperatures of the corresponding PZT compositions. The hopping conduction obeying the “universal power law” and an exponent equal to 0.88 was observed to dominate in alternating current conductivity over the entire frequency range from 10 Hz to 2 MHz at room temperature. At higher temperatures the relaxation spectrum was found to be much influenced by the increased direct current (dc) conductivity. The measured low frequency conductivity and the bulk grain dc conductance, calculated from impedance analysis indicate nearly the same Arrhenius-type thermally activated process with activation energies of 1.09 and 1.12 eV, respectively. These values were found to be in excellent agreement with those published in literature for perovskite ferroelectrics and may be attributed to motion of oxygen vacancies or field-enhanced emission of carriers from traps within the bulk.

Enhanced Ferroelectric and Dielectric Properties of CoFe2O4–Pb(Zr0.53Ti0.47)O3 Multiferroic Composite Thick Films

“…Figures 3(b) and (c) show the frequency dependence of their dielectric constant (ɛ) and loss tangent (tan δ) at room temperature. It is seen clearly that the dielectric constants are nearly kept stable in the entire frequency range except for some small dielectric dispersion at low frequency similar to that of dielectric loss, in which large dc conductivity might be induced by mobile charge carriers existed 21 . The movement of these mobile charges is suppressed at high frequency, and hence decreased dielectric loss is observed.…”

General equivalent circuit derived from capacitance and impedance measurements performed on epitaxial ferroelectric thin films

“…[1][2][3] In many of the above mentioned applications, the ferroelectric is used in capacitor geometry thus information regarding the dielectric constant, the losses by different mechanisms, and the equivalent circuit of the capacitor is necessary. [4][5][6][7][8][9] These can be obtained by performing capacitance-voltage (C-V) measurements at different temperatures and frequencies or by using impedance/dielectric spectroscopy. [10][11][12][13][14][15][16][17] Among the most studied ferroelectric materials are BaTiO 3 (BTO) and Pb(Zr,Ti)O 3 (PZT).…”

Enhanced high-field strain and reduced high-temperature dielectric loss in 0.6(Bi0.9La0.1)(Fe1−xTix)O3–0.4PbTiO3 piezoelectric ceramics

“…where the σ 0 is the pre-exponential term and E a is the conduction activated energy and k B is Boltzmann constant [12]. The value of E a of this compound is near 1 eV calculated from the slope of the fitting line, which is close to the E a of oxygen vacancies [11].…”