The influence of vacancy defects on elastic and electronic properties of TaSi (5/3) desilicides from a first-principles calculations

Chen, Jiaying; Zhang, Xudong; Ying, Caihong; Ma, He; Li, Jun; Wang, Feng; Guo, Hui

doi:10.1016/j.ceramint.2020.01.115

Cited by 63 publications

(10 citation statements)

References 67 publications

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“…The structural stability of the crystal is a critical parameter that must be taken into account when the investigations of a material are made using DFT calculations. In this regard, we have determined the formation enthalpies (

{{\Delta}}H

) for all under‐study compounds with the help of the following relation 28 :

\begin{equation}{{\Delta}}H\left( {{\mathrm{Hf}}_2{\mathrm{AX}}} \right) = \frac{1}{4}\ \left[ {E_{\mathrm{T}}^{{\mathrm{Hf}}_2{\mathrm{AX}}} - \left( {2E_{\mathrm{T}}^{{\mathrm{Hf}}} + E_{\mathrm{T}}^{\mathrm{A}} + E_{\mathrm{T}}^{\mathrm{X}}} \right)} \right]\end{equation}

where

E_{\mathrm{T}}^{{\mathrm{Hf}}_2{\mathrm{AX}}}

represents the total energy of Hf 2 AX (A═Al, Si and X═C, N) compounds, whereas

E_{\mathrm{T}}^{{\mathrm{Hf}}}

E_{\mathrm{T}}^{\mathrm{A}}

, and

E_{\mathrm{T}}^{\mathrm{X}}

demonstrate the total energies of Hf, A (Al and Si), and X (C and N) atoms, respectively. The calculated

{{\Delta}}H

values for Hf 2 SiC, Hf 2 AlC, Hf 2 SiN, and Hf 2 AlN MAX phases are listed in Table 1.…”

Section: Resultsmentioning

confidence: 99%

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First‐principles investigation of structural, mechanical, and optoelectronic properties of Hf₂AX (A═Al, Si and X═C, N) MAX phases

Ali,

Bibi,

Younis

et al. 2023

J Am Ceram Soc.

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In this work, we have employed the first‐principles calculations to investigate the phase stability and mechanical and optoelectronic characteristics of Hf2AX (A═Al, Si and X═C, N) MAX phases. Phase stabilities of Hf2AX compounds have been evaluated by the formation enthalpy computations and phonon dispersion curves, which indicate that all studied compounds are structurally and dynamically stable. The mechanical stability has been determined by elastic stiffness constants, which confirms that the studied MAX phases are mechanically stable. The computed results for Pugh's and Poisson ratios indicate the brittle nature of Hf2AX MAX phases. It is interesting to note that Si‐based MAX phases possess high values of B/G, indicating that they are harder than Al‐based compounds. The obtained band structures and partial density of states indicate the metallic character of all Hf2AX compounds. The strong hybridization of d‐orbitals of Hf with p‐orbitals of N and the comparatively weaker hybridization of p‐orbitals (Hf) with Al/Si p‐orbitals is observed. The presence of pseudogaps near the Fermi energy level emerges due to the orbital hybridization involving Hf, Al/Si, and C/N atoms. The analysis of charge density difference maps reveals the presence of a strong covalent bond between the Hf and C/N atoms, whereas a relatively weaker covalent bond is seen between the Hf and Al/Si atoms. Furthermore, numerous optical characteristics have been investigated to account for the behavior of the Hf2AX compounds to those of impinging electromagnetic rays. The highest absorptivity is noticed within the energy range of 7.5–12.5 eV. The optical spectra in the range of 1.7 eV (IR) to 9 eV ultraviolet (UV) have been observed for the investigated MAX phases, predicting their suitability as proficient energy absorbers within the UV region. The Intriguing properties of Hf2AX compounds are anticipated to be appropriate materials for a variety of applications.

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{{\Delta}}H

) for all under‐study compounds with the help of the following relation 28 :

\begin{equation}{{\Delta}}H\left( {{\mathrm{Hf}}_2{\mathrm{AX}}} \right) = \frac{1}{4}\ \left[ {E_{\mathrm{T}}^{{\mathrm{Hf}}_2{\mathrm{AX}}} - \left( {2E_{\mathrm{T}}^{{\mathrm{Hf}}} + E_{\mathrm{T}}^{\mathrm{A}} + E_{\mathrm{T}}^{\mathrm{X}}} \right)} \right]\end{equation}

where

E_{\mathrm{T}}^{{\mathrm{Hf}}_2{\mathrm{AX}}}

represents the total energy of Hf 2 AX (A═Al, Si and X═C, N) compounds, whereas

E_{\mathrm{T}}^{{\mathrm{Hf}}}

E_{\mathrm{T}}^{\mathrm{A}}

, and

E_{\mathrm{T}}^{\mathrm{X}}

demonstrate the total energies of Hf, A (Al and Si), and X (C and N) atoms, respectively. The calculated

{{\Delta}}H

values for Hf 2 SiC, Hf 2 AlC, Hf 2 SiN, and Hf 2 AlN MAX phases are listed in Table 1.…”

Section: Resultsmentioning

confidence: 99%

Section: Structural and Dynamical Stabilitiesmentioning

confidence: 99%

First‐principles investigation of structural, mechanical, and optoelectronic properties of Hf₂AX (A═Al, Si and X═C, N) MAX phases

Ali,

Bibi,

Younis

et al. 2023

J Am Ceram Soc.

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“…The stability of the vacancy structure is represented by the vacancy formation energy, which is defined by Equation (16) [ 23 ]

E_{normalf} = E_{KSN - V} - E_{KSN} + \sum (E_{normalv})

where E f is the vacancy formation energy, E KSN‐V is the total energy of the structure with vacancies, E KSN is the total energy of the perfect KSN, and E v is the total energy of the vacant atoms. The difficulty of forming defects can be explained by the degree of vacancy formation energy.…”

Section: Resultsmentioning

confidence: 99%

Effect of Intrinsic Nb⁵⁺ Vacancy on Dielectric and Polarization Behaviors of KSr₂Nb₅O₁₅: First‐Principles Investigation

Chen

Feng

Teng

et al. 2021

Physica Status Solidi (b)

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The Nb in the structure of ferroelectric KSr2Nb5O15 (KSN) is designated as Nb1 or Nb2 as it is surrounded by differing amounts of oxygen atoms. The dielectric properties and spontaneous polarization intensity of KSN with different Nb5+ vacancies are studied using first‐principles calculations and the influence mechanism of intrinsic cation vacancies on the dielectric properties and spontaneous polarization intensity of KSN is clarified. The dielectric constants and polarization responses to the materials are different when vacancy is formed at these two types of Nb sites, respectively; vacancy at the Nb1 site increases the dielectric constant, whereas vacancy at the Nb2 site decreases it. Furthermore, the experimental results support the effects of Nb5+ vacancy on the polarization behavior of the material, including polarizability and polarization intensity. This study provides a theoretical foundation for better understanding and improving the dielectric properties and polarization behavior of tungsten bronze structure ferroelectrics.

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“…Hence, it is necessary to study the influence of the various types of vacancy defects on the material properties. [14,15] Chen et al [16] used the first-principles method to investigate the influence of vacancies on both the elastic and electronic properties of Ta 5 Si 3 .…”

Section: Introductionmentioning

confidence: 99%

Impact of Point Defects and V Doping on the Thermodynamic Properties of TiB: First‐Principles Calculations

et al. 2023

Physica Status Solidi (b)

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In this work, the impact of point defects and V doped on the thermodynamic properties of TiB was calculated using the ultra‐soft pseudo‐potential approach of the plane wave based on the density functional theory (DFT). More specifically, based on the Quasi‐harmonic Debye model, the volume, heat capacity, thermal expansion coefficient, and Debye temperature of TiB with B‐vacancy, Ti‐vacancy, V substitutional doped, and V interstitial doped under high temperature and high pressure were systematically analyzed. From the calculated results, it was indicated that the presence of both types of vacancies leads to a decreasing trend for the volume. Particularly, the different forms of V doping could cause lattice distortion and affected supercell volume, whereas their volume was positively correlated with the temperature and negatively correlated with the pressure. The V interstitial doped led to an increased in both the constant volume heat capacity and the constant pressure heat capacity of TiB. In addition, regardless of the vacancy or doping‐based modification of TiB, its constant volume heat capacity increased with the temperature and approached the Dulong‐Petit limit, while the constant pressure heat capacity slowly decreased by increasing the pressure. The presence of vacancies also affected the thermal expansion coefficient of TiB, thereby regulated its high‐temperature ductility. The V interstitial doping approach was beneficial for improving the high‐temperature ductility of TiB, whereas substitutional doping was led to a decreasing trend at high pressure. The Debye temperature of TiB with vacancies was proven more sensitive to pressure changes than the temperature. On the contrary, the V doping had a significant impact on the Debye temperature of TiB, and the Debye temperature of TiB with interstitial V atoms was lower than that of TiB with substitutional V atoms, indicating that the interaction force between the substitutional atoms was higher than that of the interstitial sites.This article is protected by copyright. All rights reserved.

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The influence of vacancy defects on elastic and electronic properties of TaSi (5/3) desilicides from a first-principles calculations

Cited by 63 publications

References 67 publications

First‐principles investigation of structural, mechanical, and optoelectronic properties of Hf₂AX (A═Al, Si and X═C, N) MAX phases

First‐principles investigation of structural, mechanical, and optoelectronic properties of Hf₂AX (A═Al, Si and X═C, N) MAX phases

Effect of Intrinsic Nb⁵⁺ Vacancy on Dielectric and Polarization Behaviors of KSr₂Nb₅O₁₅: First‐Principles Investigation

Impact of Point Defects and V Doping on the Thermodynamic Properties of TiB: First‐Principles Calculations

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The influence of vacancy defects on elastic and electronic properties of TaSi (5/3) desilicides from a first-principles calculations

Cited by 63 publications

References 67 publications

First‐principles investigation of structural, mechanical, and optoelectronic properties of Hf2AX (A═Al, Si and X═C, N) MAX phases

First‐principles investigation of structural, mechanical, and optoelectronic properties of Hf2AX (A═Al, Si and X═C, N) MAX phases

Effect of Intrinsic Nb5+ Vacancy on Dielectric and Polarization Behaviors of KSr2Nb5O15: First‐Principles Investigation

Impact of Point Defects and V Doping on the Thermodynamic Properties of TiB: First‐Principles Calculations

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First‐principles investigation of structural, mechanical, and optoelectronic properties of Hf₂AX (A═Al, Si and X═C, N) MAX phases

First‐principles investigation of structural, mechanical, and optoelectronic properties of Hf₂AX (A═Al, Si and X═C, N) MAX phases

Effect of Intrinsic Nb⁵⁺ Vacancy on Dielectric and Polarization Behaviors of KSr₂Nb₅O₁₅: First‐Principles Investigation