Controlled thermal expansion and thermoelectric properties of Mg₂Si/Si composites

A thermoelectric module is composed of n- and p-type materials, and its performance is evaluated by the materials' dimensionless figure of merit, zT, which is expected to be as high as possible. Moreover, because a thermoelectric module is designed to operate in various temperature ranges, the rate of each material's deformation in response to a change in temperature, also called thermal expansion, should be considered. If n- and p-type materials in a thermoelectric module have a too large difference in the thermal expansion, it could lead to risks of several device failures and reduction in performance over time. Thus, to achieve practical use, not only zT but also the compatibility of n- and p-type materials are also crucial parameters. In this study, we demonstrated a technique used to minimize the difference of thermal expansion rate between n-type Mg₂Si and p-type higher manganese silicide, which are the promising materials used for a practical thermoelectric module.