Enhanced figure of merit of TaIrGe Half-Heusler alloy for thermoelectric applications under the effect of isotropic strain

Half-metallic ferromagnets (HMF) are one of the most essential materials for spintronics. The electronic, magnetic, optical and transport properties of hexagonal XFeSe2 (X = Li, Na and K) compounds have been investigated by Wien2K code. The Heisenberg classical model has been used to determine spin polarization. The ferromagnetism is confirmed by the negative exchange energy Δx (pd), exchange constants, and quantum interchange of electrons in strong p-d hybridization. The integer values of total magnetic moment (MT) of 5.0000 µB, 4.9995 µB, and 5.0000 µB per formula unit has further verified the HMF in LiFeSe2, NaFeSe2 and KFeSe2 respectively. Optical properties reveal that the absorption of light energy exist in visible to ultraviolet regions. Moreover, refective index, reflectivity spectrum and optical conductivity are also reported. Lastly, BoltzTraP code was used to explore the influence of electrical and thermal conductivities of electrons spin, potential gradient effect and figure of merit (ZT). Results reveal that the studied compounds are potential candidates for spintronic devices and other energy applications.

Section: Thermoelectric Propertiessupporting

confidence: 86%

“…Keeping in view the above thermoelectric results, we conclude that half-metallic XFeSe 2 (X = Li, Na and K) shows a considerable thermoelectric performance accompanied by a significant ZT larger than many halfmetallic compounds up to the best of our knowledge [65].…”

Section: Thermoelectric Propertiesmentioning

confidence: 61%

First principle study of structural, electronic, magnetic, optical and thermal properties of chalcogenides XFeSe₂ (X = Li, Na and K) half metallic compounds

Azam¹,

Nawaz²,

Murtaza³

et al. 2022

“…Over the past few years, extensive efforts have been made to find new HH alloys as potential spintronic and thermoelectric materials. The highest verifiable ZT of HH alloys is between 0.5 and 1.5 in the intermediate to high temperature range [46][47][48][49][50][51][52][53].…”

Section: Introductionmentioning

confidence: 96%

Effect of Be and P doping on the electron density, electrical and optoelectronic conduct of half-Heusler LiMgN within ab initio scheme

Ziat¹,

Zarhri²,

Belkhanchi³

et al. 2022

The effect of (Be- and P-) dopant has been investigated on the electronic structure and optoelectronic properties of LiMgN alloy, where the (Be and P) amount is 6.25%. The LiMgN alloy has an XYZ form which is crystallized in the F4 ̅3m (N° 216) space group. The “X and Y” are being substituted by Be and Z is substituted by P. The present investigation is carried out within the Wien2K package inside the TB-mBJ approximation. The present findings show that the Burstein–Moss (BM) shift is observed when Be is being in the Li position, and the Fermi level lies inside the CB. The “apparent band gap” of Be doped LiMgN semiconductor is increased as the absorption edge is pushed to higher energies as a result of some states close to the CB being populated. This conduct is significant, as it gives a chance to get different optical characteristics for the same material and the “apparent band gap” is equal to the actual band gap plus Burstein–Moss (BM) shift. The transmittance T(%) of Be element in the Y site is 76%. For the P doped LiMgN, the transmittance is 73 %.

“…Returning to some studies conducted on these compounds, we find that TaIrGe, TiIrSb, ZrIrSb, and TaIrSn exhibit semiconductor behavior with an indirect band gap (<1.5 eV) formed principally by d-d hybridization [3, 8-11, 19, 20], while they also possess a wide direct band gap for transparency (>2.5 eV) and high hole mobility making them suitable and needed for various optoelectronic applications such as solar cells, lightemitting diodes (LEDs), and flat panel displays. In addition to their suitability for optical applications, these compounds have also demonstrated good thermoelectric performance for p-type doping because of their high value of ZT ̃0.8 [11,20,21]. This dual functionality makes them highly versatile materials with applications in both energy harvesting and light emission.…”

Section: Introductionmentioning

confidence: 99%

“…The ability to efficiently convert heat into electricity while maintaining excellent optical transparency further underscores their potential for integration into diverse technological platforms However, the quest for more efficient materials has driven the development of various strategies to improve the performance of existing materials. These strategies include the development of such materials using band engineering techniques such as doping, introduction of resonant states, application of strain etc Recently, Saini et al [21] reported the effect of isotropic strain on transport properties of TaIrGe alloy using full potential linearized augmented plane-wave (FPLAPW) method and showed that applying strain to this compound induces significant changes in its electronic structure, resulting in variations in the band gap and effective masses under different strain values. This tuning of the material's electronic structure led to an improvement in its thermoelectric performance, with ZT ̃0.82 for the p-type material under 4% tensile strain at T = 1200 K, whereas it is 0.69 for pure TaIrGe compound.…”

Section: Introductionmentioning

confidence: 99%

Strain effects on electronic and dynamical properties of half-Heusler semiconductors: insights from Meta-GGA

Mellah,

Demmouche,

Bezzerga

2024

In this study, we investigated the effects of mechanical strain, including both tensile and compressive strains, on the electronic properties and dynamical stability of two ternary half-Heusler compounds: TiIrSb and ZrIrSb. We employed the plan wave pseudo-potential method (PW-PP) within the density functional theory (DFT) framework. Our calculations were performed using both the GGA-PBE and Meta-GGA-SCAN approximations. Furthermore, to compute the phonon dispersion, we employed the R2SCAN functional instead of SCAN for both compounds, addressing numerical challenges encountered with the latter.In the absence of strain, our calculations revealed that both compounds exhibit semiconducting behavior, featuring an indirect band gap at identical locations in the Brillouin Zone. Notably, the SCAN functional consistently predicted a larger band gap compared to the corresponding values obtained with PBE for both compounds. Specifically, the band gap expanded significantly, creating a noticeable separation between the valence and conduction bands. For TiIrSb, it increased from 0.84 eV with PBE to 1.05 eV with SCAN, while for ZrIrSb, it increased from 1.41 eV with PBE to 1.71 eV with SCAN. Under the application of strains, both compounds demonstrated an increased band gap under compressive strain, while the application of tensile strain led to a decrease in the band gap, resulting in an indirect-to-direct band gap transition for ZrIrSb. Remarkably, under all strain values, whether tensile or compressive, the SCAN functional consistently exhibited a larger band gap compared to PBE, indicating its accurate description of the material's electronic structure. The calculated Density of States (DOS) and Partial Density of States (PDOS) reveal that the valence band extremum (VBM) primarily consisted of Ti/Zr-d orbitals, while the conduction band maxima (CBM) predominantly involved strong hybridization between Ti/Zr-d, Ir-d, and Sb-p states. Notably, the SCAN functional predicted higher orbital contributions to Total Density of States (TDOS) compared to the PBE approximation. Importantly, both half-Heusler materials exhibited mechanical and dynamical stability under various strain condition