A consequence of the low reliability is that the predicted compounds (especially ones that have not yet been experimentally made) with promising thermoelectric performance may be experimentally identified as metastable or unstable. Yet a key challenge is to balance the reliability and cost in such studies. This has provided the motivation for high-throughput methods and other theoretical approaches that use predictions of properties to identify candidate materials 15, 16. As a result, there is a clear need for more efficient rational approaches to discovering new promising materials. However, such a traditional process becomes increasingly time-consuming.
Half heusler phono dispersio trial#
Historically, the materials discovery has mostly relied on the Edisonian trial and error approach. In the meantime, relentless efforts have also been devoted to discovering promising new compounds that have unusual characteristics enabling favorable combinations of high electrical conductivity, large Seebeck coefficient, and low thermal conductivity. Therefore, research on thermoelectric materials has focused on identifying approaches that can effectively decouple the key transport parameters for enhancing the ZT of existing materials 9, 10, 11, 12, 13, 14. The transport parameters on which ZT depends are strongly interrelated with each other due to their different, and typically opposite, dependencies on carrier concentration and electronic structure 8. It is defined as ZT = SσT/( κ lat+ κ ele), where S is the Seebeck coefficient, σ is the electrical conductivity, κ lat is the lattice thermal conductivity, κ ele is the electronic thermal conductivity, and T is the absolute temperature 3, 4, 5, 6, 7. However, the wide application of thermoelectric power generation systems requires significant improvements in the energy conversion efficiency, which essentially depends on the materials’ dimensionless figure-of-merit ( ZT). As one of the clean energy conversion techniques, thermoelectric power generation can harvest waste heat and convert it into electricity via the Seebeck effect 1, 2. The ever-increasing energy consumption from fossil-fuel combustion has led to alarming environmental impacts. Our work demonstrates that the TaFeSb-based half-Heuslers are highly promising for thermoelectric power generation. Such an extraordinary thermoelectric performance is further verified by the heat-to-electricity conversion efficiency measurement and a high efficiency of ~11.4% is obtained. Additionally, an ultrahigh average ZT of ~0.93 between 300 and 973 K is achieved. Among them, the p-type TaFeSb-based half-Heusler demonstrates a record high ZT of ~1.52 at 973 K. By adopting this approach, here we have discovered several unreported half-Heusler compounds. Compared to the traditional materials discovery, the inverse design approach has the potential to substantially reduce the experimental efforts needed to identify promising compounds with target functionalities. However, recent progress in theoretical calculations, including the ability to predict structures of unknown phases along with their thermodynamic stability and functional properties, has enabled the so-called inverse design approach. Also, the positive pressure dependence of Curie Temperature (TC) as a function of V/V0 for all the compounds is studied and the highest TC = 646.1 K for Co2CrAl is observed under compression corresponding to V/V0 = 0.85.Discovery of thermoelectric materials has long been realized by the Edisonian trial and error approach. In addition, ferromagnetic nature of all these compounds is explained by the exchange interactions at both ambient and under compression. Further, an electronic topological transition (ETT) is also observed in Co2CrGa as a function of compressive strain corresponding to V/V0 = 0.85, driving the system towards the half-metallic nature. Hydrostatic compressive strain is applied to all the systems and Co2CrGa turned out to be a half metal at compressive strain corresponding to V/V0 = 0.85 with 100% spin polarization and the percentage of spin polarization for Co2CrIn gets enhanced as a function of compressive strain.
Mechanical and dynamical stabilities of all the investigated compounds are confirmed using elastic tensor analysis and phonon dispersion plots respectively at ambient as well as under compression. At ambient condition, Co2CrAl exhibits half metallic nature while Co2CrGa possesses nearly half metallic nature and Co2CrIn shows metallic nature.
Half heusler phono dispersio full#
In the present study, we report a systematic first principles study which investigates and tunes the percentage of spin polarization in few Co-based full Heusler alloys Co2CrX (X = Al, Ga and In) under hydrostatic strain. Įnhanced Curie temperature and spin polarization in Co-based compounds under pressure: A first principles investigation.įull text not available from this repository.
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