Synthesis of porous thermoelectric devices

A number of studies have been performed in order to improve energy efficiency of thermoelectric materials and systems. The thermoelectric porous devices which utilize heat convection by gas flow through the porous device has been proposed to achieve high energy efficiency by Echigo et al. For the porous devices, porosity ratio and permeability of gas, which significantly affect convectional heat transfer in porous media, are important properties as well as thermoelectric properties. However, because many thermoelectric materials such as FeSi₂, (Bi,Sb)₂Te₃ and PbTe are generally brittle, development of processing of porous thermoelectric devices has been hoped. A novel hot press method was able to form porous thermoelectric devices of the brittle FeSi₂, (Bi,Sb)₂Te₃ and PbTe materials. In this method, open ratio was controlled up to 35% and permeability in order of 10^-9 or 10^-10 m². Based on the processing, the functional-graded porous thermoelectric devices can be formed. Synthesis and optimization of the porous thermoelectric device including functionally graded device is discussed