The rare earth perovskite LaRhO3(s): impedance measurements

The electrical properties of sintered LaRhO3 pellet were studied by means of impedance spectroscopy measurements with Solartron 1260 frequency analyzer. AC impedance was measured in air from 469 K to 657 K at regular intervals in the frequency range of 0.1 Hz - 10 MHz with an applied excitation signal of 100 mV. The temperature was controlled by a microprocessor and measured by a K-type thermocouple placed very close to the sample. Typical comparative Nyquist plots recorded at different temperatures by impedance spectroscopy in which the plot of imaginary impedance (-Z') vs. Real Impedance (Z) were obtained by changing frequency from 1 Hz to 10 MHz. These plots give a series of semicircles which are attributed to grain conduction (σg) as no differentiation between bulk and grain boundary could be demarcated. Small inductor attributable to electrode polarization, at extremely low frequency appears and is due to extrinsic factors and is ignored. In the Nyquist plot the impedance decreases with increasing temperature