Measurement of the Seebeck coefficient under high pressure by dual heating

This study presents a new method for measuring the Seebeck coefficient under high pressure in a multi-anvil apparatus. The application of a dual-heating system enables precise control of the temperature difference between both ends of the sample in a high-pressure environment. Two pairs of W-Re thermocouples were employed at both ends of the sample to monitor and control the temperature difference, and independent probes were arranged to monitor the electromotive force (emf) produced by temperature oscillation at a given target temperature. The temperature difference was controlled within 1 K during the resistivity measurements to eliminate the influence of the emf owing to a sample temperature gradient. The Seebeck measurement was successfully measured from room temperature to 1400 K and was obtained by averaging the two measured values with opposite thermal gradient directions (similar to 20 K). Thermoelectric properties were measured on disk-shaped p-type Si wafers with two different carrier concentrations as a reference for high Seebeck coefficients. This method is effective to determine the thermoelectric power of materials under pressure.