First Principle Study on Mg2X (X = Si, Ge, Sn) Intermetallics by Bi Micro-Alloying

Bai, Guoning; Tian, Jinzhong; Guo, Qianqian; Li, Zhiqiang; Zhao, Yuhong

doi:10.3390/cryst11020142

Cited by 5 publications

(2 citation statements)

References 54 publications

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“…There has been a lot of focus in recent years on the development of new efficient thermoelectric materials used in the fabrication of the applications mentioned above [3]. Compounds based on magnesium Mg 2 X have emerged as attractive materials for converting heat into electricity in an efficient way due to their unique properties, such as high-temperature resistance, superior corrosion resistance and a reasonably high melting point [5][6][7]. Furthermore, these compounds are environmentally beneficial, as they consist of nontoxic, earth abundant and cost-effective elements, unlike other compounds which are based on tellurides and other heavy elements [8,9].…”

Section: Introductionmentioning

confidence: 99%

Response of Mg₂X (X = Si, Ge and Sn) compounds to extreme uniaxial compression: first-principles calculations

Behar,

Meskine,

Boukortt

et al. 2024

Modelling Simul. Mater. Sci. Eng.

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In this study, we perform first-principles calculations using density functional theory to examine the structural, electronic, thermodynamic, and thermoelectric properties of the Mg2X (X = Si, Ge and Sn) compounds under uniaxial compression within the generalized gradient and modified Beck-Johnson approximations. It is found that the band gap of Mg2Si, Mg2Ge and Mg2Sn decreases with applied uniaxial pressure and changes its direction from Г-Х to Г-К. The results of phonon frequencies indicate that the studied compounds are dynamically stable at zero and higher uniaxial strains. Furthermore, the uniaxial compression and temperature dependence of the Gibbs free energy, heat capacity and thermal expansion coefficient are investigated in the frame of the quasi-harmonic approximation. The semiclassical-Boltzmann method is used to study the Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit ZT as a function of both temperature and uniaxial pressure. It is shown that the Seebeck coefficient decreases with increasing pressure whereas thermal conductivity increases, which leads to the lowering in the value of ZT and thus to a worse thermoelectric performance of the studied materials.

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Section: Introductionmentioning

confidence: 99%

Response of Mg₂X (X = Si, Ge and Sn) compounds to extreme uniaxial compression: first-principles calculations

Behar,

Meskine,

Boukortt

et al. 2024

Modelling Simul. Mater. Sci. Eng.

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show abstract

“…There has been an intensive theoretical effort to study these compounds, mainly using density functional theory (DFT) [1,14,15,[30][31][32][33][34][35][36][37][38]. The theoretical studies can provide deep and independent insight into the physics of these compositions and shed light on delicate aspects.…”

Section: Introductionmentioning

confidence: 99%

Machine-learned model Hamiltonian and strength of spin–orbit interaction in strained Mg₂X (X = Si, Ge, Sn, Pb)

Alidoust¹,

Rothmund²,

Akola³

2022

J. Phys.: Condens. Matter

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Machine-learned multi-orbital tight-binding (MMTB) Hamiltonian models have been developed to describe the electronic characteristics of intermetallic compounds Mg2Si, Mg2Ge, Mg2Sn, and Mg2Pb subject to strain. The MMTB models incorporate spin-orbital mediated interactions and they are calibrated to the electronic band structures calculated via density functional theory (DFT) by a massively parallelized multi-dimensional Monte-Carlo search algorithm. The results show that a machine-learned ﬁve-band tight-binding model reproduces the key aspects of the band structures in the entire Brillouin zone. The ﬁve-band model reveals that compressive strain localizes the contribution of the 3s orbital of Mg to the conduction bands and the outer shell p orbitals of X (X = Si, Ge, Sn, Pb) to the valence bands. In contrast, tensile strain has a reversed eﬀect as it weakens the contribution of the 3s orbital of Mg and the outer shell p orbitals of X to the conduction bands and valence bands, respectively. The π bonding in the Mg2X compounds is negligible compared to the σ bonding components, which follow the hierarchy |σsp| > |σpp| > |σss|, and the largest variation against strain belongs to σpp. The ﬁve-band model allows for estimating the strength of spin-orbit coupling (SOC) in Mg2X and obtaining its dependence on the atomic number of X and strain. Further, the band structure calculations demonstrate a signiﬁcant band gap tuning and band splitting due to strain. A compressive strain of −10% can open a band gap at the Γ point in metallic Mg2Pb, whereas a tensile strain of +10% closes the semiconducting band gap of Mg2Si. A tensile strain of +5% removes the three-fold degeneracy of valence bands at the Γ point in semiconducting Mg2Ge. The presented MMTB models can be extended for various materials and simulations (band structure, transport, classical molecular dynamics), and the obtained results can help in designing devices made of Mg2X.

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Study of high-temperature electrical conductivity and thermoelectric performance in Mg2−δSi0.35−xSn0.65Gex (δ = 0–0.04 and x = 0, 0.05) intermetallic alloys

Rao

Sarkar²,

Singh³

et al. 2022

J Mater Sci: Mater Electron

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First Principle Study on Mg2X (X = Si, Ge, Sn) Intermetallics by Bi Micro-Alloying

Cited by 5 publications

References 54 publications

Response of Mg₂X (X = Si, Ge and Sn) compounds to extreme uniaxial compression: first-principles calculations

Response of Mg₂X (X = Si, Ge and Sn) compounds to extreme uniaxial compression: first-principles calculations

Machine-learned model Hamiltonian and strength of spin–orbit interaction in strained Mg₂X (X = Si, Ge, Sn, Pb)

Study of high-temperature electrical conductivity and thermoelectric performance in Mg2−δSi0.35−xSn0.65Gex (δ = 0–0.04 and x = 0, 0.05) intermetallic alloys

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First Principle Study on Mg2X (X = Si, Ge, Sn) Intermetallics by Bi Micro-Alloying

Cited by 5 publications

References 54 publications

Response of Mg2X (X = Si, Ge and Sn) compounds to extreme uniaxial compression: first-principles calculations

Response of Mg2X (X = Si, Ge and Sn) compounds to extreme uniaxial compression: first-principles calculations

Machine-learned model Hamiltonian and strength of spin–orbit interaction in strained Mg2X (X = Si, Ge, Sn, Pb)

Study of high-temperature electrical conductivity and thermoelectric performance in Mg2−δSi0.35−xSn0.65Gex (δ = 0–0.04 and x = 0, 0.05) intermetallic alloys

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Response of Mg₂X (X = Si, Ge and Sn) compounds to extreme uniaxial compression: first-principles calculations

Response of Mg₂X (X = Si, Ge and Sn) compounds to extreme uniaxial compression: first-principles calculations

Machine-learned model Hamiltonian and strength of spin–orbit interaction in strained Mg₂X (X = Si, Ge, Sn, Pb)