A first-principles study on the mechanical and thermodynamic properties of (Nb<sub>1−x</sub>Ti<sub>x</sub>)C complex carbides based on virtual crystal approximation

Hua, Guomin; Li, Dongyang

doi:10.1039/c5ra22756a

Cited by 22 publications

(12 citation statements)

References 62 publications

(59 reference statements)

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“…The finding that no long-range ordering is present in the TM layer of NMC allows us to use the virtual crystalline approximation (VCA) method which treats the TM elements as disordered alloying atoms (details in the Computational Methods). 30 The VCA model significantly reduces the computational cost and smoothly handles the stoichiometric variation in the five NMC compositions. Here we use both the supercell model and the VCA method to calculate the elastic modulus of NMC.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Electronic Structure and Comparative Properties of LiNi_xMn_yCo_zO₂ Cathode Materials

2017

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We study the electronic structure and valence states in LiNi x Mn y Co z O2 (NMC) materials and compare the resulting electronic, structural, mechanical, and thermal properties of a class of NMC compositions. The Jahn–Teller distortion in the transition metal (TM) octahedral complex allows us to determine the ionic states of the TM elements. The variation of Ni2+/Ni3+ and Co2+/Co3+ as the NMC composition changes alters the structural stability, electrical conductivity, lattice parameters, elastic modulus, and thermal stability. The theoretical predictions are in excellent agreement with the experimental results. Through intensive computational screening, we further show that long-range atomic ordering is absent in the NMC lattice due to the mixture of the ionic states and similar ionic radii of the TM elements. The first-principles modeling provides a theoretical foundation on a complete understanding of the physicochemical properties of NMC at the level of electronic structures.

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Section: ■ Results and Discussionmentioning

confidence: 99%

“…Based on the phonon structure, thermal properties are calculated by the finite volume method using the quasi-harmonic approximation according to the following equations …”

Section: Methodsmentioning

confidence: 99%

Electronic Structure and Comparative Properties of LiNi_xMn_yCo_zO₂ Cathode Materials

2017

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“…The VCA-DFT method as implemented in the Vienna Ab initio Simulation Package (VASP) has found successful applications in studying TMC systems such as WSe2(1-x)Te2x [83]. The VCA-DFT method has also been used to obtain structural properties [84,85], phase determination [86], and electronic properties such as band gaps and effective masses of carriers [87,88], the results of which are all comparable to experiments [89,90]. Therefore, utilizing the VCA-DFT method is helpful in characterizing the CCAs of different compositions, facilitating materials screening and selection for different applications.…”

Section: Introductionmentioning

confidence: 95%

High‐Throughput Computational Characterization of 2D Compositionally Complex Transition‐Metal Chalcogenide Alloys

Wang

Liu

Basu

2020

Advcd Theory and Sims

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2D binary transition‐metal chalcogenides (TMCs) such as molybdenum disulfide exhibit excellent properties required for energy conversion applications. Alloying binary TMCs can form 2D compositionally complex TMC alloys (CCTMCAs) that possess remarkable properties from the constituent TMCs. High‐throughput workflow performing density functional theory (DFT) calculations based on the virtual crystal approximation (VCA) model (VCA‐DFT) is designed. The workflow is tested by predicting properties including in‐plane lattice constants, band gaps, effective masses, spin–orbit coupling, and band alignments of the Mo‐W‐S‐Se, Mo‐W‐S‐Te, and Mo‐W‐Se‐Te 2D CCTMCAs. The VCA‐DFT results are validated by computing the same properties using unit cells and supercells of selected compositions. The VCA‐DFT results of the abovementioned five properties are comparable to that of DFT calculations, with some inaccuracies in several properties of MoSTe and WSTe. Moreover, 2D CCTMCAs can form type II heterostructures as used in photovoltaics. Finally, Mo0.5W0.5SSe, Mo0.5W0.5STe, and Mo0.5W0.5SeTe 2D CCTMCAs are used to demonstrate the room‐temperature entropy‐stabilized alloys. They also exhibit high electrical conductivities at 300 K, promising for light adsorption devices. This work shows that the high‐throughput workflow using VCA‐DFT calculations provides a tradeoff between efficiency and accuracy, opening up opportunities in the computational design of other 2D CCTMCAs for various applications.

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“…Here, β‐Si 3 (C x ,N 1− x ) 4 silicon carbonitride crystallized into hexagonal structure in group of P6 3 /m, and properties were calculated based on the alloying pseudopotential for the carbon and nitrogen atoms, the alloying pseudopotential was constructed within first‐principles virtual crystal approximation (VCA) scheme. The basic principle of VCA is to mix the individual pseudopotential of atoms to build virtual pseudopotential as

V_{VCA}^{normalps} [x] = x V_{solute}^{normalps} + (1 - x) V_{solvent}^{normalps}

. Recently, VCA has become popular when using first‐principles methods to handle alloy disorder.…”

Section: Methodologies and Materialsmentioning

confidence: 99%

“…ÞV ps solvent . 26,27 Recently, VCA has become popular when using first-principles methods to handle alloy disorder. The VCA method has been shown to successfully study alloys containing not only monovalent atoms but also heterovalent atoms.…”

Section: First-principles Calculationsmentioning

confidence: 99%

Influence of carbon on stability, mechanical property, electronic structure, and lattice dynamics of silicon carbonitride

Hua

Zhong

et al. 2018

J Am Ceram Soc

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In this study, first‐principles calculations were performed to study the stability, mechanical property, electronic structure and lattice dynamics of β‐Si3(Cx,N1−x)4 silicon carbonitride. The solubility of carbon in β‐Si3(Cx,N1−x)4 having a stable structure is shown to be about 15 at.%. Within the limit of solubility, an increase in carbon concentration in β‐Si3(Cx,N1−x)4 will lead to a decrease in the Young's modulus and density and an increase in the Poisson's ratio. The study of deformation behavior shows that the most likely slip system of 11¯000001 is on prismatic plane rather than on basal plane. This feature of β‐Si3(Cx,N1−x)4 is similar to WC. In addition, the ductility and fracture toughness of β‐Si3(Cx,N1−x)4 can be optimized by controlling the carbon concentration. The improvement in ductility and fracture toughness can be attributed to the formation of metallic bonds by the incorporation of carbon atoms. The lattice dynamics study shows that the structural stability of β‐Si3(Cx,N1−x)4 is controlled by energy stability criteria under stress‐free condition. In the stressed state, the structural stability of β‐Si3(Cx,N1−x)4 is controlled by the elastic stability criteria. Subsequently, the β‐Si3(Cx,N1−x)4 solid solution was prepared by self‐propagating high‐temperature synthesis (SHS), and the carbon‐concentration‐dependent mechanical properties were consistent with the first‐principles calculations. The maximum fracture toughness of 10.4 MPa·m0.5 was obtained in β‐Si3(Cx,N1−x)4 at carbon concentration of 5 wt%, which means that the solid solution toughening can be used as a supplement to crack bridging toughening and phase transition toughening for ceramic toughening. The results obtained in this study reveal that the β‐Si3(Cx,N1−x)4 solid solution is a promising candidate for high‐speed ceramic bearings.

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A first-principles study on the mechanical and thermodynamic properties of (Nb_1−xTi_x)C complex carbides based on virtual crystal approximation

Abstract: Tailoring the properties of complex carbides was achieved by component control, which enables it as a better candidate for specific application.

Cited by 22 publications

References 62 publications

Electronic Structure and Comparative Properties of LiNi_xMn_yCo_zO₂ Cathode Materials

Electronic Structure and Comparative Properties of LiNi_xMn_yCo_zO₂ Cathode Materials

High‐Throughput Computational Characterization of 2D Compositionally Complex Transition‐Metal Chalcogenide Alloys

Influence of carbon on stability, mechanical property, electronic structure, and lattice dynamics of silicon carbonitride

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A first-principles study on the mechanical and thermodynamic properties of (Nb1−xTix)C complex carbides based on virtual crystal approximation

Abstract: Tailoring the properties of complex carbides was achieved by component control, which enables it as a better candidate for specific application.

Cited by 22 publications

References 62 publications

Electronic Structure and Comparative Properties of LiNixMnyCozO2 Cathode Materials

Electronic Structure and Comparative Properties of LiNixMnyCozO2 Cathode Materials

High‐Throughput Computational Characterization of 2D Compositionally Complex Transition‐Metal Chalcogenide Alloys

Influence of carbon on stability, mechanical property, electronic structure, and lattice dynamics of silicon carbonitride

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A first-principles study on the mechanical and thermodynamic properties of (Nb_1−xTi_x)C complex carbides based on virtual crystal approximation

Electronic Structure and Comparative Properties of LiNi_xMn_yCo_zO₂ Cathode Materials

Electronic Structure and Comparative Properties of LiNi_xMn_yCo_zO₂ Cathode Materials