Measurement of non-equilibrium characteristics of thermoelectric materials

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The study of material properties relies on accurate and reliable testing instruments. Sensitively capturing changes in material performance is key to understanding the mechanisms of material properties. The Seebeck coefficient and resistivity testing instrument are essential for research on many functional materials. However, the current instrument is limited in its ability to capture sensitive changes due to testing principles. Here, we prepared three different types of non-equilibrium Zn4Sb3. We found that the existing static testing instrument has problems with testing interruption or inaccuracy when the sample undergoes chemical reactions, rapid atomic diffusion, or phase transitions. The cause of interruption is that the temperature control setting cannot meet the accuracy requirements of the testing instrument. The instrument's large temperature difference setting will cause the determination of the phase transition temperature to become inaccurate. To address the limitations, we have developed a dynamic testing instrument and tested the Seebeck coefficient and resistivity of Zn4Sb3 and Ni in the range of 300 K–800 K. By ensuring the accuracy of each module of the instrument, optimizing the alternating temperature rise time, and improving the data acquisition calculation method, we have achieved accurate capture of sensitive performance changes in the non-equilibrium sample. Comparatively, dynamic testing reduces the measurement time by approximately 300 % compared to static testing. The standard deviation of measured Seebeck coefficient and resistivity is less than ±4 %. This study demonstrates that dynamic testing of the Seebeck coefficient and resistivity is an effective strategy for measuring non-equilibrium functional materials.