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Article Dans Une Revue Journal of Alloys and Compounds Année : 2023

Coupling of electronic transport and defect engineering substantially enhances the thermoelectric performance of p-type TiCoSb HH alloy

Résumé

Further advancements in thermoelectric technology rely on the capacity to control both electrical and thermal transport properties simultaneously. Although TiCoSb-based half-Heusler compounds are pro- mising for mid-range-temperature thermoelectric applications owing to their high Seebeck coefficient and good electrical conductivity, their high thermal conductivity has been so far the main issue to overcome. Here, we show that a combined approach of tuning the electronic properties and defect engineering en- hances the thermoelectric performance of p-type TiCoSb-based compounds. By alloying on the Co and Ti sites with Fe and Zr, respectively, an overall increase in the peak ZT value of up to ∼90% at 823 K is achieved in Ti0.8Zr0.2Co0.85Fe0.15Sb. This enhancement is directly tied to the more pronounced metallic nature of transport upon Fe alloying combined with a significant reduction in thermal conductivity due to mass and strain field fluctuations driven by the substitution of Zr for Ti, as evidenced by the Debye-Callaway model. Further adjusting the hole concentration with aliovalent Sn doping leads to an additional increase in ZT, eventually leading to a peak value of ∼0.54 at 823 K in Ti0.8Zr0.2Co0.85Fe0.15Sb0.96Sn0.04, which is 224% higher than in TiCo0.85Fe0.15Sb, and the highest value reported so far in Hf-free p-type TiCoSb based HH alloys.
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Dates et versions

hal-04017415 , version 1 (07-03-2023)

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Ajay Kumar Verma, Kishor Kumar Johari, Paritosh Dubey, Christophe Candolfi, Bertrand Lenoir, et al.. Coupling of electronic transport and defect engineering substantially enhances the thermoelectric performance of p-type TiCoSb HH alloy. Journal of Alloys and Compounds, 2023, 947, pp.169416. ⟨10.1016/j.jallcom.2023.169416⟩. ⟨hal-04017415⟩
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