About this Abstract | 
  
   
    | Meeting | 
    2020 TMS Annual Meeting & Exhibition
       | 
  
   
    | Symposium 
       | 
    Alloys and Compounds for Thermoelectric and Solar Cell Applications VIII
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    | Presentation Title | 
    Thermoelectric Half Heusler Systems {Nb,Ta}FeSb - Ti1+xFe1.33-xSb | 
  
   
    | Author(s) | 
    Peter F. Rogl, Andrij  Grytsiv, Vitaliy  Romaka, Ali  Tavassoli, Gerda  Rogl, Ernst  Bauer | 
  
   
    | On-Site Speaker (Planned) | 
    Peter F. Rogl | 
  
   
    | Abstract Scope | 
    
Based on detailed phase diagram studies employing SEM, EPMA, XPD, the thermoelectric potential of Half-Heusler compounds in the title systems has been elucidated for 4.2K-900K. Investigations of physical properties (including mechanical behavior) were backed by DFT.  Ti-Fe-Sb reveals an extensive homogeneity region: 800°C, Ti1+xFe1.33-xSb (-0.17-0.25). The TE performance increased with Fe/Co substitution and reached ZT = 0.42 for TiCo0.5Fe0.665Sb. 
We have synthesized the HHphases, TaFeSb, Ta1-xTixFeSb (0-0.1 and 4.2-823K) via melting. TaFeSb forms below 850°C via TaSb2+TaFe2 = 2TaFeSb. Physical properties of Ta1-xTixFeSb (0-0.1 and 4.2-823K) show a gradual change from semiconducting to metallic behaviour. Although Sv exhibits its largest values (above 230muV/K) for x=0.03, the peak of pf (above 6mW/mK2) was observed for x=0.06, due to rather low electrical resistivities. In combination with the suppressed phonon thermal conductivity, due to a unique role of Ti, ZT900K=1.0 for Ta0.94Ti0.06FeSb, close to the highest values reported for Hf-free p-type HH-systems. | 
  
   
    | Proceedings Inclusion? | 
    Planned: Supplemental Proceedings volume |