Glass‐ceramic composites as insulation material for thermoelectric oxide multilayer generators

Abstract

AbstractThermoelectric generators can be used as energy harvesters for sensor applications. Adapting the ceramic multilayer technology, their production can be highly automated. In such multilayer thermoelectric generators, the electrical insulation material, which separates the thermoelectric legs, is crucial for the performance of the device. The insulation material should be adapted to the thermoelectric regarding its averaged coefficient of thermal expansion α and its sintering temperature while maintaining a high resistivity.In this study, starting from theoretical calculations, a glass‐ceramic composite material adapted for multilayer generators from calcium manganate and calcium cobaltite is developed. The material is optimized towards an α of 11 × 10−6 K−1 (20–500°C), a sintering temperature of 900°C, and a high resistivity up to 800°C. Calculated and measured α are in good agreement. The chosen glass‐ceramic composite with 45 vol.% quartz has a resistivity of 1 × 107 Ωcm and an open porosity of <3%. Sintered multilayer samples from tape‐cast thermoelectric oxides and screen‐printed insulation show only small reaction layers. It can be concluded that glass‐ceramic composites are a well‐suited material class for insulation layers as their physical properties can be tuned by varying glass composition or dispersion phases.