Determination of thermal expansion coefficient for thermoelectric CaMnO3 with a shadow method

Abstract

We have measured thermal expansion coefficient of a bulk CaMnO3 thermoelectric module with a cylindrical shape, using a shadow method. The CaMnO3 module has been heated from the room temperature up to 773 K. At each temperature, the shadow image has been recorded by a CMOS camera and reconstructed with a HoloViewer program in MATLAB. Then the diameters of the module have been obtained at different temperatures in the region 300–773 K. Finally, we have determined the linear thermal expansion and the thermal expansion coefficient for CaMnO3. Our results demonstrate that the expansion coefficient for the bulk CaMnO3 thermoelectric module depends linearly on the temperature in the region under study.