Silver-antimony-telluride (AgSbTe 2 ) based compounds have emerged as a promising class of materials for thermoelectric (TE) power generation at the mid-temperature range. This Chapter demonstrates utilization of irst-principles calculations for predicting TE properties of AgSbTe 2 -based compounds and experimental validations. Predictive calculations of the efects of La-doping on vibrational and electronic properties of AgSbTe 2 compounds are performed applying the density functional theory (DFT), and temperature-dependent TE transport coeicients are evaluated applying the Bolzmann transport theory (BTE). Experimentally, model ternary (AgSbTe 2 ) and quaternary (3 at. % La-AgSbTe 2 ) compounds were synthesized, for which TE transport coeicients were measured, indicating that thermal conductivity decreases due to La-alloying. The later also reduces electrical conductivity and increases Seebeck coeicients. All trends correspond with those predicted from irst-principles. Thermal stability issues are essential for TE device operation at service conditions, e.g. changes of matrix composition and second-phase precipitation, and are also addressed in this study on both computational and experimental aspects. It is shown that La-alloying afects TE igure-of-merit positively, e.g., improving from 0.35 up to 0.50 at 260 °C. We highlight the universal aspects of this approach that can be applied for other TE compounds. This enables us screening their performance prior to synthesis in laboratory.Keywords: silver-antimony-telluride, irst-principles calculations, thermoelectric transport properties, Bolzmann transport theory, latice dynamics, thermal stability
IntroductionIt is of utmost technological importance to develop predictive tools that will provide us with information about design of materials' functional properties. In this context, density functional theory (DFT) irst-principle calculations ofer us such possibilities [1][2][3][4] Despite of relatively high ZT values of AgSbTe 2 phase, it is still challenging to increase them to the range of 2-3. Reaching at this limit will enable us employing this material for energy conversion at power levels >500 W [34]. Reduction in latice thermal conductivity is a conventional way to enhance TE performance and is achieved by either doping with solute elements [35] or formation of second phases to stimulate phonon scatering [36][37][38]. These latice defects afect, of course, electronic properties, mainly electrical conductivity and Seebeck coeicient. Atempts to improve TE properties of AgSbTe 2 -based alloys by doping with diferent elements [19,25,[39][40][41][42][43][44][45][46][47] Notwithstanding the aforementioned successful experimental and computational atempts, a set of experimental routines, that is initiated and directed by predictions from irst principles for complete TE performance or any other computational procedure, is missing.
Thermoelectrics for Power Generation -A Look at Trends in the Technology 148A signiicant step in this direction is introduced by o...