The Electronic Transport Channel Protection and Tuning in Real Space to Boost the Thermoelectric Performance of Mg_(3+δ)Sb_(2-y)Bi_(y) near Room Temperature

The optimization of thermoelectric materials involves the decoupling of the transport of electrons and phonons.In this work,an increased Mg_(1)-Mg_(2) distance,together with the carrier conduction network protection,has been shown as an effective strategy to increase the weighted mobility(U=μm∗3/2)and hence thermoelectric power factor of Mg_(3+δ)Sb_(2-y)Bi_(y) family near room temperature.Mg_(3+δ)Sb_(0.5)Bi_(1.5) has a high carrier mobility of 247 cm^(2)V^(-1) s^(-1) and a record power factor of 3470μWm^(-1) K^(-2) at room temperature.Considering both efficiency and power density,Mg_(3+δ)Sb_(1.0)Bi_(1.0) with a high average ZT of 1.13 and an average power factor of 3184μWm^(-1) K^(-2) in the temperature range of 50-250℃ would be a strong candidate to replace the conventional n-type thermoelectric material Bi_(2)Te_(2.7)Se_(0.3).The protection of the transport channel through Mg sublattice means alloying on Sb sublattice has little effect on electron while it significantly reduces phonon thermal conductivity,providing us an approach to decouple electron and phonon transport for better thermoelectric materials.

Room-temperature thermoelectric materials: Challenges and a new paradigm

Room-temperature thermoelectric materials provide promising solutions for energy harvesting from the environment,and deliver a maintenance-free power supply for the internet-of-things(IoTs).The currently available Bi_(2)Te_(3) family discovered in the 1950s,still dominates industrial applications,however,it has serious disadvantages of brittleness and the resource shortage of tellurium(1×10^(-3) ppm in the earth's crust).The novel Mg_(3)Sb_(2) family has received increasing attention as a promising alternative for room-temperature thermoelectric materials.In this review,the development timeline and fabrication strategies of the Mg 3 Sb 2 family are depicted.Moreover,an insightful comparison between the crystal-linity and band structures of Mg_(3)Sb_(2) and Bi_(2)Te_(3) is drawn.An outlook is presented to discuss challenges and new paradigms in designing room-temperature thermoelectric materials.