First principles study of the thermodynamic, mechanical and electronic properties of crystalline phases of Chromium Nitrides

Tenelanda-Osorio, Laura Isabel; Vélez, Mario

doi:10.1016/j.jpcs.2020.109692

Cited by 8 publications

(2 citation statements)

References 42 publications

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“…The cohesive energy (

) is calculated to determine the thermodynamic stability of the structures. The

, which is the necessary energy to separate the solids in atoms at stable states, was calculated using the following equation [ 43 , 44 ],

where

is the total energy of the bulk, and

, and

are the total energy of each element. Furthermore, N Cs , N Bi, and N Na/K are the number of atoms of each element in the unit cell.…”

Section: Resultsmentioning

confidence: 99%

Promising Bialkali Bismuthides Cs(Na, K)2Bi for High-Performance Nanoscale Electromechanical Devices: Prediction of Mechanical and Anisotropic Elastic Properties under Hydrostatic Tension and Compression and Tunable Auxetic Properties

et al. 2021

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Using first-principles calculations, we predict highly stable cubic bialkali bismuthides Cs(Na, K)2Bi with several technologically important mechanical and anisotropic elastic properties. We investigate the mechanical and anisotropic elastic properties under hydrostatic tension and compression. At zero pressure, CsK2Bi is characterized by elastic anisotropy with maximum and minimum stiffness along the directions of [111] and [100], respectively. Unlike CsK2Bi, CsNa2Bi exhibits almost isotropic elastic behavior at zero pressure. We found that hydrostatic tension and compression change the isotropic and anisotropic mechanical responses of these compounds. Moreover, the auxetic nature of the CsK2Bi compound is tunable under pressure. This compound transforms into a material with a positive Poisson’s ratio under hydrostatic compression, while it holds a large negative Poisson’s ratio of about −0.45 along the [111] direction under hydrostatic tension. An auxetic nature is not observed in CsNa2Bi, and Poisson’s ratio shows completely isotropic behavior under hydrostatic compression. A directional elastic wave velocity analysis shows that hydrostatic pressure effectively changes the propagation pattern of the elastic waves of both compounds and switches the directions of propagation. Cohesive energy, phonon dispersion, and Born–Huang conditions show that these compounds are thermodynamically, mechanically, and dynamically stable, confirming the practical feasibility of their synthesis. The identified mechanisms for controlling the auxetic and anisotropic elastic behavior of these compounds offer a vital feature for designing and developing high-performance nanoscale electromechanical devices.

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“…The cohesive energy (

) is calculated to determine the thermodynamic stability of the structures. The

, which is the necessary energy to separate the solids in atoms at stable states, was calculated using the following equation [ 43 , 44 ],

where

is the total energy of the bulk, and

, and

are the total energy of each element. Furthermore, N Cs , N Bi, and N Na/K are the number of atoms of each element in the unit cell.…”

Section: Resultsmentioning

confidence: 99%

Promising Bialkali Bismuthides Cs(Na, K)2Bi for High-Performance Nanoscale Electromechanical Devices: Prediction of Mechanical and Anisotropic Elastic Properties under Hydrostatic Tension and Compression and Tunable Auxetic Properties

et al. 2021

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show abstract

“…Also, because C and N have different numbers of electrons, the hybridizations of their orbitals with those of Cr differ. This means that the formation of Cr-C compounds in general is more energetically favorable than the formation of Cr-N compounds, because fewer antibonding states are filled [30][31][32][33][34]. This is reflected in their formation enthalpies, which are more negative for two out of the three stable Cr-C phases than for the Cr-N phases [35].…”

Section: Bonding Differencesmentioning

confidence: 99%