HALF HEUSLER PHONO DISPERSIO CODE

15 developed a scheme to calculate the carrier mobility, effective mass and lattice thermal conductivity related to TE performances and Sparks et al. As a result, a theoretical prediction from first-principles calculations and other methods has been of interest for a long time 13, 14, 15, 16. These issues are thus appealing materials computation and property design as a pre-requisite for exploring TE materials for favorable applications. By the way, technically, a reliable measurement of the κ tot and evaluation of its two components (κ l, κ e) seem to be tricky and thus the reported data are sometimes authors-dependent. Given this dilemma, an optimization of all these properties so that the largest PF and ZT can be obtained simultaneously is far beyond fast-track experimental explorations. Good electrical conduction usually corresponds to high thermal conductivity and a counteracted relationship between the S and σ is often observed, resulting in the complex relationships between these physical parameters ( S, T, σ, κ l and κ e). Conceptually, in order to possess a large ZT, the PF must be large and the total thermal conductivity κ tot should be minimized. The thermally-driven electrical performance of a TE material is measured by the power factor ( PF = S 2σ), while a high heat-to-electricity conversion efficiency is scaled by ZT. A good TE material should have high figure of merit ZT = ( S 2σ/κ tot) T, where S, σ, κ tot (=κ l + κ e), T, represent the Seebeck coefficient, electrical conductivity, total thermal conductivity and absolute temperature and κ l and κ e are the lattice and electronic components, respectively. Thermoelectric (TE) power generators that enable the direct conversion from heat to electricity have been studied for a long time, much earlier than the claimed energy crisis 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. The present methodology represents an effective and powerful approach to calculate the whole set of thermoelectric properties for thermoelectric materials.Īt least as much as the energy we used on earth is lost in the form of waste heat 1. The calculated results show good agreement with experimental data. In sequence, the density functional perturbation combined with the quasi-harmonic approximation and the Klemens’ equation is implemented for calculating the lattice thermal conductivity of carrier-doped thermoelectric materials such as Ti-doped NbFeSb compounds without losing a generality. The finite-temperature electronic transport is evaluated within the framework of Boltzmann transport theory.

HALF HEUSLER PHONO DISPERSIO CODE

The electronic structure is computed using the WIEN2k code and the carrier relaxation times for electrons and holes are calculated using the Bardeen and Shockley’s deformation potential (DP) theory. In this work, we present a full-scale computation scheme based on the first-principles calculations by choosing a set of doped half-Heusler compounds as examples for illustration. These issues make a full-scale computation of the whole set of thermoelectric parameters particularly attractive, while a calculation scheme of the electronic and phononic contributions to thermal conductivity remains yet challenging. Our calculations showed that these two compounds are mechanically, elastically and dynamically stable as cubic half-Heusler alloys.The thermoelectric performance of materials relies substantially on the band structures that determine the electronic and phononic transports, while the transport behaviors compete and counter-act for the power factor PF and figure-of-merit ZT. From the thermodynamic properties of these compounds, it was revealed that these compounds are soft at low temperature, but at a high temperature they tend to be hard materials. The phonon dispersion curve predicts the dynamically stabilities of these half-Heusler alloys. Although the phonon dispersion curves for HfNiGe and HfNiSn are similar with splitting at the Γ point, the shift in their frequency was as a result of the mass different in Ge and Sn. Also, the mechanical and elastical stabilities of these compounds were confirmed from the comparison of the elastic constants of these compounds with conditions for stabilities. From our results, we reported the energy gap of 0.38 eV for HfNiSn and 0.61 eV for HfNiGe indicating the semiconductor property of these compounds. The PBE functional as implemented in Projector augmented-wave (PAW) pseudopotentials was used for all the calculations. In this work, details density functional theory calculations were performed to obtain the electronic, elastic, phonon and thermodynamic properties of half-Heusler alloys HfNiX (X = Ge and Sn). Physics with Eletronics Unit, Department of Science Laboratory Technology Moshood Abiola Polytechnics,

Adebayo 2 bĭepartment of Physical Sciences, Bells University of Technology,ĭepartment of Physics, Federal University of Agriculture,ĭepartment of Physics, Augustine University,

Half heusler phono dispersio