The AC Impedance Response of the Physical Interface Between Yttria‐Stabilized Zirconia and YBa2Cu3 O 7 − x

Abstract

Composite electrochemical cells incorporating press-contact pellets of yttria-stabilized zirconia (YSZ), electronically blocking electrodes, and YBa2Cu3OT_= (YBCO) were investigated by ac impedance spectroscopy. An additional element, net attributable to either of the individual components, was observed in the impedance spectrum of the composite cell. Although the capacitance associated with the additional element (~10 -~ F) appeared to indicate a bulk response, the capacitance was found to be invariant with dimensions of either the YBCO or YSZ components. A similar additional element was observed when YBCO was replaced by other electronically conducting materials, including gold foil. These results point clearly to an interfacial impedance whose characteristics are governed largely by the YSZ; the extremely low capacitance value arises from a very low effective contact area (10-3%) due to surface roughness. We found no features in the impedance spectrum which could be attributed to oxide ion conduction in YBCO. In the assignment of impedance spectra to the components of a heterogeneous system, it is demonstrated that the use of relaxation frequencies (f,~ = [RC] -~) and their temperature dependences provide a useful comparison, free from geometric factors, between samples with different origins or thermal histories.

Lithium-Ion Trapping from Local Structural Distortions in Sodium Super Ionic Conductor (NASICON) Electrolytes

“…11,25−28 In the case of solid-state ion conductors, electric modulus spectroscopy often provides more-instructive spectra, as the modulus is inversely related to capacitance (M* = 1/C*) and the bulk microregions of the material typically have the smallest capacitance by 2−3 orders of magnitude, when compared with the grain boundaries. [19][20][21]29 For this analysis, M″ vs f was plotted and the critical frequency of the loss peak corresponding to the bulk response was followed over the temperature sweeps. Figure 5a shows selected data points recorded for LGP that demonstrate the temperature dependence of the imaginary modulus loss peak position.…”

Conductivity studies of sol-gel prepared BaCe0.85−xZrxY0.15O3−δ solid electrolytes using impedance spectroscopy

“…The simple semi-empirical Debye-type model as well as accurate fitting via non-linear least squares of constant-phase elements were used; both Unit-Weight and Calc-Modulus approximations [22] were used to obtain RC parameters (R is the resistance, C is the capacitance) of the solid electrolyte material which are straightforward to components of the microstructure. In addition of C and R, f rel and s (f rel is relaxation frequency and s is the time constant) were extracted [23]. Measuring of f rel and its temperature or composition dependences may be particularly useful in comparing samples which have different geometries, different microstructures or have been prepared in different way.…”

Phase diagrams for the YBa2Cu3O7 family — ANNO 1996

“…Also determinations from the individual oxygen-ion conductivities have been attempted, based on dc-or ac-conductivity measurements with electronically blocking, yttria-stabilized, zirconia electrodes [548,570,571]. However, the most recent studies combine this method with ac-impedance spectroscopy, recognizing the profound importance of the contact/interface phenomena on such measurements [572,573].…”