A Study on the Relationship between the Thermoelectric Properties and Infrared Emission Performance of ZnO/SrTiO₃ Composite Materials

The thermoelectric properties and infrared emissivity of materials may seem unrelated, but both are influenced by electrical conductivity and thermal conductivity. The photothermal effect of SrTiO₃ can establish a connection between the Seebeck coefficient and infrared absorption in the 8-14 μm range. However, there is currently limited research on the relationship between thermoelectric performance and infrared emissivity. In this study, ZnO/SrTiO₃ composites were prepared using a hydrothermal method combined with spark plasma sintering. The intrinsic relationship between the thermoelectric and infrared emission performance of the composites was investigated by varying the ZnO content. As the ZnO content increased, the grain boundary barrier of the samples changed, affecting both electrical and thermal conductivities. The infrared emissivity initially decreased and then increased with increasing ZnO content, which contrasted with the trend observed in electrical conductivity, in accordance with the Hagen-Rubens relationship. The <i>ZT</i> value and infrared emissivity exhibited opposite trends, with the ZnO-5 sample having the highest thermoelectric performance and the lowest infrared emissivity, making it the most representative sample. The relationship between the thermoelectric performance and infrared emissivity of SrTiO₃ is of significant importance for developing multifunctional materials with both thermoelectric and infrared properties.