Demixing and ordering in Ni(Ti,Zr)(Sb,Sn) half-Heusler materials

Area of Science:

• Materials Science
• Solid State Physics
• Computational Materials Science

Background:

• Half-Heusler materials are promising thermoelectrics.
• Controlling phase separation is key to enhancing thermoelectric properties.

Purpose of the Study:

• Investigate phase separation and ordering in Ni(Ti,Zr)(Sb,Sn) alloys.
• Understand the influence of stoichiometry and temperature on material structure.

Main Methods:

• Density Functional Theory (DFT)
• Monte Carlo simulations
• Mean-field modeling

Main Results:

• Observed demixing and ordering phenomena upon cooling.
• Demixing occurs in both (Ti,Zr) and (Sb,Sn) sublattices, with varying degrees.
• A second phase separation in the Sb/Sn sublattice was identified at 200 K for a specific Sn:Sb ratio.

Conclusions:

• Phase separation patterns in Ni(Ti,Zr)(Sb,Sn) provide insights for nano-structuring.
• These findings aid in developing strategies to improve the figure of merit for thermoelectric applications.