MSE 2016 - Full Program

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Lecture

Interface characterization by computational methods of phase separated NiSn-based thermoelectric half-Heuslers.

Tuesday (27.09.2016)
15:00 - 15:15
Part of:


We combine Density Functional Theory calculations and Monte Carlo simulations to study the thermodynamic conditions for phase separation in NiSn-based half-Heuslers up to the scale of 200 nm. Here we observed that for a wide range of concentrations, Ti-rich regions coexist with Ti-poor regions below the critical temperature T*. In the alloy NiTi_{1-x}Hf_xSn this critical temperature is T* = 500 K and for NiTi_{1-x}Hf_xSn T* = 900 K. We present a detailed analysis of the interface morphology, since it is here where the phonon and electron scattering events can modify the transport properties that lead to higher figure of merits on these thermoelectric materials. We extend the length of our studies to the micrometer scale by means of a phase field method, where the Cahn-Hilliard diffusion equation is derived from a free energy density containing a potential and an interfacial energy obtained from the Monte Carlo simulations.


J. Miranda Mena, H.G. Schoberth, T. Gruhn, H. Emmerich, Journal of alloys and compounds, 650, 728 (2015).

J. Miranda Mena, H.G. Schoberth, T. Gruhn, H. Emmerich, Acta Materialia, 111, 157, (2016)

J. Miranda Mena, E. Rausch, S. Ouardi, T. Gruhn, H.G. Schoberth, G.H. Fecher, H. Emmerich, C. Felser, Journal of Electr. Materials, 45, 1382 (2016)

J. Miranda Mena, H.G. Schoberth, T. Gruhn, H. Emmerich, Phys. Stat. Solid A, 213, 706, (2016)

 

Speaker:
Dr. Joaquin Miranda
University of Bayreuth
Additional Authors:
  • Dr. Thomas Gruhn
    University of Bayreuth
  • Prof. Dr. Heike Emmerich
    University of Bayreuth