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Structural Disorder in TiFeSb Half-Heusler Antimonide

Vitaliy Romaka1 romakav [at] lp.edu.ua
Zlata Rykavets1
Volodymyr Krayovskyy1
Lyubov Romaka2
  1. Department of Materials Science and Engineering, Lviv Polytechnic National University, Ukraine, Lviv, Ustiyanovycha 5.
  2. Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Ukraine, Lviv, Kyryla & Mephodiya street 6.
Abstract 

The DFT modeling of the TiF1+xSb solid solution revealed that composition TiFe1.375Sb with MnCu2Al structure type is more preferable than equiatomic TiFeSb which crystallizes in MgAgAs-type. At T > 873 K the formation of the two phase region containing both half-Heusler and fullHeusler phases is predicted. The composition dependence of the lattice parameter shows deviation from linearity. The calculations explain the difficulties in solid solutions formation based on TiFeSb intermetallic.

Keywords 
DFT modeling
half-Heusler phases
structural disorder
thermoelectric material
thermodynamics
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