 # Seebeck coefficient

If two electrical conductors are in contact with each other forming a closed cycle, there can result an electric voltage if the touching point and the point where the voltage is measured have different temperatures. The resulting voltage is given by the equation: SA and SB are the Seebeck-coefficients, which are depending on material and temperature. T1 and T2 represent the different temperatures. The Seebeck-coefficient has the unit [Volt/Kelvin]. If the temperature difference is very small and the Seebeck-coefficients stay constant, U=(SB-SA)*(T2-T1) will be assumed.

The voltage is produced by thermal diffusion due to high-energy electrons at the warm contact point that are diffusing to the negative side. This causes a constant electron transport from the positive to the negative conductor while also heat energy is transferred resulting in a lower Seebeck effect.

The efficiency a thermocouple is higher the higher the electrical conductivity and the smaller the thermal conductivity of the conductor material is.

Decisive for the characteristics of a conductor is the figure of merit. This parameter, also known as “ZT” includes the temperature, the Seebeck-coefficient (square), the thermal conductivity and electrical conductivity. The scheme shows the behavior of insulators, metals and semiconductors. The carrier concentration, seebeck coefficient and thermal conductivity give the characteristic value “ZT” or “figure of merit” that describes the thermoelectric behavior of any material with one value.

## Applications determining the Seebeck coefficient

###### Application: Accuracy Seebeck – Constantan sample Presented here is the Seebeck measurement result from a Constantan Sample, measured with an LSR-3/800. Additionally shown are literature values for this material. It can clearly be seen that the measurement results is in agreement with the corresponding literature data within 2%.

###### Application: Measurement of a sample of the tellur family ## Linseis measuring instruments for the determination of the Seebeck coefficient

### TEG-Tester

Linseis TEG Tester is a measurement system for temperature dependent conversion efficiency evaluations for thermoelectric generators (TEGs)

### LSR-3

Most advanced Seebeck Coefficient and Electric Resistivity (LSR) charac- terization of Bulk material and Thin-Films

### TFA

Unique device for a comprehensive thin film characterization from the nm to the µm scale

### LZT Meter

LZT-Meter – Perfect tool for thermoelectric applications

Temperature range:

• -150 up to 500°C
• RT up to 800
• RT up to 1100/1500°C