In two-probe impedance measurements the interfacial impedance between metal
electrode and ionic conductor contributes to the measured impedance. There
fore a calculation procedure which separates the bulk from the interfacial
impedance must be applied. The separation procedure can be avoided by measu
ring the bulk conductivity in the four-probe arrangement. The impedance of
polycrystalline samples and single crystals of the oxygen ion conductor BIC
UVOX.10 was measured in the a.c. two- and four-probe configuration. The fre
quency range was 0.1 to 1 x 10(6) Hz in the case of two-probe measurements
and 0.1 to 1 X 10(5) Hz in the case of four-probe measurements. For single
crystals, impedance spectra were taken in the direction parallel to the oxy
gen-conducting layers. The results of bulk conductivity obtained by four- a
nd two-probe measurements were in agreement for polycrystalline samples and
for single crystals. The origin of inductive loops visible for single crys
tals in the impedance spectra taken by the four-probe method is explained i
n a qualitative fashion as an interfacial effect at the voltage electrodes.
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