INSTRUMENTATION FOR AC 4-PROBE MEASUREMENTS OF LARGE IMPEDANCES

An ac four-probe set-up was constructed to measure impedance spectra b etween 1 Hz and 100 kHz on solid electrolytes up to impedance values o f 10 G Omega. The influence of the system on the measurement was analy sed for the previous and the new set-up. A solution to minimise the so urce of errors by pre-amplifiers for current and voltage signals is pr esented. A new sample holder was constructed for best results in conju nction with the new Pre-amplifiers, The holder is designed for measure ments on solid electrolytes over a wide temperature range. The perform ance of the improved set-up and the residual error sources are discuss ed. Measurements of impedance spectra on YSZ and BICUVOX.10 in a four- probe arrangement are given as an example. (C) 1997 Elsevier Science S .A.