Characterization of electrical properties of n-conducting barium titanate as a function of dc-bias and ac-voltage amplitude by application of impedance spectroscopy

Abstract

The electrical properties of bulk and grain boundaries of donor-doped barium titanate ceramics have been characterized as a function of temperature (50-350°C) and voltage load (up to 140 V) by application of impedance spectroscopy. Both the grain boundary resistivities and the steepness of the R-T characteristics are diminished significantly with increasing voltage load. While the grain boundary resistances are strongly affected by the applied electric field, the grain boundary capacitance is almost independent of the dc-bias. The non-linearity of the resistivity of n-conducting BaTiO 3 has been investigated in detail by impedance spectroscopy as a function of dc-bias and a small ac-voltage signal as well as impedance measurements with high ac-voltage amplitudes (zero bias). The non-linear current response to high ac-voltage amplitudes at low frequencies (0.01 Hz) has been determined experimentally and analyzed by means of fast Fourier transform (FFT) as well as Lissajous analyses. Moreover, a finite element model (FEM) has been developed for the simulation of the ac-current response. The FEM calculations are in close agreement with the experimentally determined data for the variation of the grain boundary resistance with ac-voltage amplitude.

Evaluation of the fuel cell performances of TiO2/PAN electrospun carbon-based electrodes

“…In an impedance mechanism, if impedance on the electrode surface increases, the semicircle part shows a larger radius but if diffusion of the electrons is higher semicircle gets smaller and linear part shows a higher slope. If the dominant effect in the electrochemical reaction mechanism is diffusion, this type of impedance is called Warburg Impedance [56]. Figure 6B shows that TiO 2 +PAN/PGE shows a Warburg type of an impedance spectrum while PGE exhibits two serial semicircles.…”