Fabrication and testing of Mg2Si1-xSnx based thermoelectric generator module

Mg2Si1-xSnx solid solutions have been of great interest for the advantages they hold as prospective thermoelectric (TE) materials. Despite this, the development of thermoelectric generator (TEG) modules fabricated entirely from these materials has not been reported. In this work, a TEG module consisting of Mg(2)Si(0.3)Sn(0.7 )n and p legs has been fabricated, and its thermoelectric generator characteristics were studied as a function of the applied temperature gradient. For then and p doped legs, compositions with peak zT values of similar to 1.6 and similar to 0.44, respectively, were synthesized using induction assisted melt synthesis. Mono-block sintering technique was adopted as a single-step compaction cum contacting technique. In order to create low resistive well-bonded contacts, an additional interfacial layer was placed between the TE material and the outer Cu layer. The TE legs were assembled into a skeletal module comprising of two unicouples electrically connected by Cu bridges. The transient state I-V characteristics of the TE device were measured at various temperature gradients (Delta T). A maximum power output value of 192mW (corresponds to a power density of 0.52 W/cm(2)) and open-circuit voltage of 200 mV were measured for a Delta T of 331 K. The measured I-V and power output data showed good agreement with the simulated power output values with a variation of only 3% until Delta T = 300 K and 5% at Delta T = 331 K. The TE module simulator was further used to estimate the device efficiency (eta) and indicated a maximum value of 5%. This is the highest reported conversion efficiency of a silicide based module (in the studied temperature range) and highlights the possibility of their commercialization in the near future.

Automated summary

In this study, a TEG module consisting of Mg(2)Si(0.3)Sn(0.7) n and p legs was fabricated and its thermoelectric generator characteristics were investigated. Compositions with peak zT values of approximately 1.6 and 0.44 for n and p doped legs, respectively, were synthesized successfully using induction assisted melt synthesis. The maximum power output and efficiency of the TE device were measured, showing promise for commercialization in the future.