Improved materials for thermoelectric conversion (generation)

Thermoelectric conversion (TEC) presents several advantages compared to the other energy conversion technology: they are reliable, can operate untainted in hostile environments, and are also environmentally friendly. However their application has been limited up to now because of the relatively low conversion efficiency of traditional thermoelectric materials used in the devices. New more efficient materials are needed. The value of a material for thermoelectric power generation is defined by the thermoelectric figure of merit Z which is a function of the Seebeck coefficient S, electrical resistivity ρ, and thermal conductivity k and is defined as Z = S²/ρk. A choice of the optimal technique for the leg formations from synthesized thermoelectric materials, which are capable to provide the leg required forms and leg geometrical sizes, are determined by mechanical properties. Several methods for a thermoelectric efficiency increase that have been put forward over the past years. Among them we wish to focus our attention to produce segment thermoelectric leg with variation of the composition along legs. Calculated efficiency in this case is more than 10% (Th = 500 °C, T_c = 50 °C). The first experimental results on 2-stage composite leg indicate the high efficiency in the thermoelectric energy conversion. Crystal-growth techniques with high crystalline perfection stimulates us to use this method for preparation the thermoelectric generator material.