Electrochemical Impedance Spectroscopy

1. Obtain a test module and hook it up to the EIS instruments via two electrodes. The test module, pictured in Figure 3, provides data that can be used to model a simple, known circuit. It can be used to confirm that the wires are hooked up to the machine correctly and that all the machinery parts are functioning.

Figure 3: Test module.

2. To start flowing current through the sample, open the Zplot software on the computer. From this software you can set up the parameters for your sample as needed. When running a test on the test module, under "Polarization", set the DC Potential to 0, AC Amplitude to 10 mV, and make sure the drop-down arrow says, "vs. Open Circuit". Under the section "Frequency sweep", set the initial frequency to 1x10^6 Hz, the final frequency to 100 Hz, and interval to 10. Also select "logarithmic" and "Steps/Decade". Then press "okay" to start a new reading.
3. Open the Zview software to view the results. Select z' and z'' to plot. The results will be shown on the negative axis-to show them on the positive axis, multiply by -1. Click "measure" then "sweep" to get the measured z' and z'' values. Compare these measured values to the expected values found on the front of the test module, as seen in Figure 2. If the values match, continue to step 4. If not, check all the wiring and equipment to see that everything is connected and functioning properly.
4. Detach the electrodes from the test module.
5. Prepare the sample; for demonstration we will be using a commercially available beta alumina by putting it in the assembly shown in Figure 4. Insert this assembly into the tube furnace, which is located in the hood fume. This set-up is necessary because EIS tests are usually run by varying amplitude (or voltage) and temperature over a certain time frame. For simplification, we will run this experiment at room temperature only.

Figure 4: Assembly that sample will be inserted into.

6. Attach the electrodes to the assembly as shown in Figure 5.

Figure 5: Sample assembly, in the hood fume, with electrodes attached.

7. Open the Zplot software and set the parameters. For this experiment, the parameters will be the same as they were in step 2.
8. Obtain the plots using the same procedure as step 3 (except the z' and z'' values do not need to be compared to the test module). Save the plots.
9. Click the "instant fit" button and choose two points to fit the semi-circle. Use the software to choose the best equivalent circuit model.