Electronic, elastic and dynamical properties of MgSe under pressure: rocksalt and iron silicide phase

Wu, Hai; Chen, Y.H.; Deng, C.R.; Han, Xiangyu; Yin, Peng

doi:10.1080/14786435.2015.1047427

Cited by 2 publications

(1 citation statement)

References 33 publications

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“…Because all the studied MX (M = Mg, Ca, Sr, and Ba and X = O, S, Se, and Te) compounds crystallize in the cubic ( Fm 3̅ m ) structure, they have three independent elastic constants such as longitudinal ( C 11 ), transverse ( C 12 ), and shear ( C 44 ) due to symmetry constraints ( C 11 = C 22 = C 33 , C 12 = C 13 = C 23 , C 44 = C 55 = C 66 , and C ij = C ji ). The calculated second-order elastic constants are given in Table S4 and are consistent with the available ultrasonic pulse echo − and Brillouin scattering measurements as well as with previous first-principles calculations. ,,,− The obtained elastic constants satisfy the Born stability criteria indicating the mechanical stability of all these MX (M = Mg, Ca, Sr, and Ba and X = O, S, Se, and Te) compounds. We then computed bulk ( B ) and shear ( G ) moduli from the calculated elastic constants with Voigt–Reuss–Hill (VRH) approximation using eqs and , respectively. Later, the obtained B and G values are used to calculate Young’s modulus ( E ) using eq .…”

Section: Results and Discussionsupporting

confidence: 80%

Anomalous Lattice Thermal Conductivity in Rocksalt IIA–VIA Compounds

Roshan

Yedukondalu

Muthaiah

et al. 2021

ACS Appl. Energy Mater.

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Materials with an intrinsic (ultra)low lattice thermal conductivity (k L ) are critically important for the development of efficient energy conversion devices. In the present work, we have investigated microscopic origins of low k L behavior in BaO, BaS, and MgTe by exploring lattice dynamics and phonon transport of 16 isostructural MX (M = Mg, Ca, Sr, and Ba and X = O, S, Se, and Te) compounds in the rocksalt (NaCl)-type structure. Anomalous trends are observed for k L in MX (M = Mg, Ca, Sr, and Ba and X = O, S, Se, and Te) compounds except for the MgX (X = O, S, Se, and Te) series in contrast to the expected trend from their atomic mass. The underlying mechanisms for such low k L behavior in large mismatch atomic mass systems, namely, BaO, BaS, and MgTe, are thoroughly analyzed. We propose the following factors that might be responsible for low k L behavior in these materials: (1) high mass contrast provides a phonon gap between the acoustic and optic branches; (2) softening of transverse acoustic (TA) phonon modes due to the presence of heavy element; (3) low-lying optic (LLO) phonon modes fall into the acoustic mode region and are responsible for softening of the acoustic phonon modes or enhancing the overlap between LLO (TO) and longitudinal acoustic (LA) phonon modes, thereby increasing scattering rates; (4) shorter phonon lifetimes; and (5) a relatively high density (ρ) and a large Gruneisen parameter (γ) leads to strong anharmonicity. Moreover, tensile strain causes a further reduction in k L for BaO, BaS, and MgTe through phonon softening and near ferroelectric instability. Our comprehensive study on 16 binary MX (M = Mg, Ca, Sr, and Ba and X = O, S, Se, and Te) compounds provides a pathway for designing (ultra)low k L materials through phonon engineering even with simple crystal systems.

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Section: Results and Discussionsupporting

confidence: 80%

Anomalous Lattice Thermal Conductivity in Rocksalt IIA–VIA Compounds

Roshan

Yedukondalu

Muthaiah

et al. 2021

ACS Appl. Energy Mater.

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<i>Ab-Initio</i> Self-Consistent Density Functional Theory Description of Rock-Salt Magnesium Selenide (MgSe)

Ayirizia¹,

Malozovsky²,

Franklin³

et al. 2020

MSA

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We report results on electronic, transport, and bulk properties of rock-salt magnesium selenide (MgSe), from density functional theory (DFT) calculations. We utilized a local density approximation (LDA) potential and the linear combination of atomic orbitals formalism (LCAO). We followed the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF), to perform a generalized minimization of the energy, down to the actual ground state of the material. We describe the successive, self-consistent calculations, with augmented basis sets, that are needed for this generalized minimization. Due to the generalized minimization, our results have the full, physical content of DFT, as per the second DFT theorem [AIP Advances, 4, 127104 (2014)]. Our calculated, indirect bandgap of 2.49 eV, for a room temperature lattice constant of 5.460 Å, agrees with experimental findings. We present the ground-state band structure, the related total and partial densities of states, DOS and PDOS, respectively, and electron and hole effective masses for the material. Our calculated bulk modulus of 63.1 GPa is in excellent agreement with the experimental value of 62.8 ± 1.6 GPa. Our predicted equilibrium lattice constant, at zero temperature, is 5.424 Å, with a corresponding indirect bandgap of 2.51 eV. We discuss the reasons for the agreements between our findings and available, corresponding, experimental ones, particularly for the band gap, unlike the previous DFT results obtained with ab-initio LDA or GGA potentials.

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Electronic, elastic and dynamical properties of MgSe under pressure: rocksalt and iron silicide phase

Cited by 2 publications

References 33 publications

Anomalous Lattice Thermal Conductivity in Rocksalt IIA–VIA Compounds

Anomalous Lattice Thermal Conductivity in Rocksalt IIA–VIA Compounds

<i>Ab-Initio</i> Self-Consistent Density Functional Theory Description of Rock-Salt Magnesium Selenide (MgSe)

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Electronic, elastic and dynamical properties of MgSe under pressure: rocksalt and iron silicide phase

Cited by 2 publications

References 33 publications

Anomalous Lattice Thermal Conductivity in Rocksalt IIA–VIA Compounds

Anomalous Lattice Thermal Conductivity in Rocksalt IIA–VIA Compounds

&lt;i&gt;Ab-Initio&lt;/i&gt; Self-Consistent Density Functional Theory Description of Rock-Salt Magnesium Selenide (MgSe)

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<i>Ab-Initio</i> Self-Consistent Density Functional Theory Description of Rock-Salt Magnesium Selenide (MgSe)