DFT insights into the electronic structure, mechanical behaviour, lattice dynamics and defect processes in the first Sc-based MAX phase Sc2SnC

Abstract The ceramic and metallic properties of the MAX phases make them attractive for numerous technological applications. The very recent experimental synthesis of the first scandium (Sc) based MAX phase Sc2SnC is an important addition to the MAX phase family as it further expands the diversity of physical characteristics of this family. Here we employ density functional theory (DFT) calculations to investigate the structural, electronic, mechanical, lattice dynamical properties of Sc2SnC including defect processes to compare with those of existing M2SnC phases. The calculated structural properties are in good agreement with the experimental values. The new phase Sc2SnC is structurally, mechanically and dynamically stable. Sc2SnC is metallic with a mixture of covalent and ionic character. The covalency of Sc2SnC including M2SnC is mostly controlled by the effective valence. Sc2SnC in M2SnC family ranks second in the scale of deformability, softness and machinability. The elastic anisotropy level in Sc2SnC is moderate compared to the other M2SnC phases. Like other members of the M2SnC family, Sc2SnC has the potential to be etched into 2D MXenes and has the potential to be a thermal barrier coating (TBC) material. The hardness and melting point of Sc2SnC, including M2SnC, follows the trend of bulk modulus.

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Exfoliation Energy as a Descriptor of MXenes Synthesizability and Surface Chemical Activity

10.20944/preprints202012.0308.v1 ◽

2020 ◽

Author(s):

Daniel Dolz ◽

Ángel Morales-García ◽

Francesc Viñes ◽

Francesc Illas

Keyword(s):

Density Functional ◽

Co2 Adsorption ◽

Selective Extraction ◽

Chemical Activity ◽

Max Phase ◽

Surface Chemical ◽

Block Element ◽

Max Phases ◽

Functional Theory ◽

Chemical Descriptor

MXenes are two-dimensional nanomaterials isolated from MAX phases by the selective extraction of the A component —a p-block element. The MAX phase exfoliation energy, Eexf, is regarded as a chemical descriptor of the MXene synthesizability. Here we show, by density functional theory estimations of the Eexf values for 486 different MAX phases, that Eexf decreases i) when MAX is a nitride, ii) when going along a d series of the metal M component, iii) when going down a group of the p-block A element, as well as iv) when having thicker MXene phases. Furthermore, Eexf is found to bias, even to govern, the surface chemical activity, as evaluated here on the CO2 adsorption strength, so that more unstable MXenes, displaying larger Eexf values, display a stronger attachment of species upon.

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First-principles calculations for transition phase, mechanical and thermodynamic properties of ZnS under extreme condition

International Journal of Modern Physics B ◽

10.1142/s021797921750028x ◽

2017 ◽

Vol 31 (05) ◽

pp. 1750028 ◽

Cited By ~ 3

Author(s):

Tao Yang ◽

Daijun Liu ◽

Junyi Ji ◽

Jianjun Chen ◽

Yang Yu ◽

...

Keyword(s):

Thermodynamic Properties ◽

Bulk Modulus ◽

Density Functional ◽

Elastic Anisotropy ◽

Extreme Condition ◽

Generalized Gradient ◽

Functional Theory ◽

Brittle Behavior ◽

Phase Transition Pressure ◽

Experimental Values

The structural and mechanical properties of ZnS in both B3 and B1 phases have been investigated by the generalized gradient approximation (GGA) within the plane-wave pseudopotential density functional theory (DFT). The obtained lattice parameters and bulk modulus of ZnS for both B3 and B1 structures are well in line with the available theoretical and experimental results. Using the enthalpy–pressure data, we have predicted that the phase transition pressure of ZnS from B3 to B1 is 17.26 GPa, which is in good agreement with previous experimental values. The hydrostatic pressure-dependent elastic properties of the two structures, such as bulk modulus, shear modulus and Young’s modulus, are discussed. Then, the mechanical characteristics of ZnS, including ductile/brittle behavior and elastic anisotropy of the two cubic single-crystal structures, are investigated in details. Furthermore, the thermodynamic properties of ZnS under extreme condition are explored by quasi-harmonic Debye modeling. The calculated results show that the ductility and elastic anisotropy increase with pressure clearly except the ductility of B1. Besides, the temperature and pressure dependencies of the heat capacity and the Debye temperature are obtained and analyzed in the wide ranges.

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Electronic structure, first and second order physical properties of MPS4: a theoretical study

Materials Science-Poland ◽

10.1515/msp-2016-0060 ◽

2016 ◽

Vol 34 (2) ◽

pp. 275-285

Author(s):

Tahar Dahame ◽

Bachir Bentria ◽

Houda Faraoun ◽

Ali Benghia ◽

A.H. Reshak

Keyword(s):

Electronic Structure ◽

Physical Properties ◽

Density Functional ◽

Population Analysis ◽

Second Order ◽

Ionic Character ◽

Modern Theory ◽

Functional Theory ◽

Electro Optic ◽

Experimental Values

AbstractWe have calculated the electronic structure and physical properties of metal thiophosphate compounds InPS4 and AlPS 4by means of pseudopotential density functional theory (DFT) coupled with the modern theory of polarization. The targeted physical properties are ﬁrst and second order optical properties as well as elastic, piezoelectric and electro-optic coefﬁcients. Furthermore, population analysis is presented in order to evaluate the covalent-ionic character of the constituent bonds. The calculated elastic constants, refractive indices and second order optical coefﬁcients of InPS4 are in good agreement with experimental values. With the absence of any theoretical or experimental physical properties of AlPS4, we predict that this compound has high piezoelectric coefﬁcients with d14 = − 73.82 pm/V, d25 = − 10.96 pm/V and d36 = 28.19 pm/V.

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Density-functional-theory predictions of mechanical behaviour and thermal properties as well as experimental hardness of the Ga-bilayer Mo2Ga2C

Journal of Advanced Ceramics ◽

10.1007/s40145-021-0531-9 ◽

2022 ◽

Vol 11 (2) ◽

pp. 273-282

Author(s):

Xinxin Qi ◽

Weilong Yin ◽

Sen Jin ◽

Aiguo Zhou ◽

Xiaodong He ◽

...

Keyword(s):

First Principles ◽

Density Functional ◽

Harmonic Approximation ◽

Max Phase ◽

Max Phases ◽

Functional Theory ◽

High Temperature Heat Capacity ◽

Stiffness Model ◽

Temperature Heat ◽

Increasing Temperature

AbstractMo2Ga2C is a new MAX phase with a stacking Ga-bilayer as well as possible unusual properties. To understand this unique MAX phase structure and promote possible future applications, the structure, chemical bonding, and mechanical and thermodynamic properties of Mo2Ga2C were investigated by first-principles. Using the “bond stiffness” model, the strongest covalent bonding (1162 GPa) was formed between Mo and C atoms in Mo2Ga2C, while the weakest Ga-Ga (389 GPa) bonding was formed between two Ga-atomic layers, different from other typical MAX phases. The ratio of the bond stiffness of the weakest bond to the strongest bond (0.33) was lower than 1/2, indicating the high damage tolerance and fracture toughness of Mo2Ga2C, which was confirmed by indentation without any cracks. The high-temperature heat capacity and thermal expansion of Mo2Ga2C were calculated in the framework of quasi-harmonic approximation from 0 to 1300 K. Because of the metal-like electronic structure, the electronic excitation contribution became more significant with increasing temperature above 300 K.

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Cubic Perovskite Pb(Mg1/3Nb2/3)O3: A Damage Tolerant, Machinable, and Thermal barrier coating material

Zeitschrift für Naturforschung A ◽

10.1515/zna-2018-0334 ◽

2018 ◽

Vol 74 (1) ◽

pp. 71-81 ◽

Cited By ~ 12

Author(s):

M.A. Hadi ◽

M.N. Islam ◽

M.H. Babu

Keyword(s):

Thermal Barrier Coating ◽

Density Functional ◽

Mechanical Stability ◽

Thermal Barrier ◽

Max Phases ◽

Functional Theory ◽

Barrier Coating ◽

Bonding Properties ◽

Shock Resistance ◽

Damage Tolerant

AbstractIn this article, we use first-principles density functional theory (DFT), with plane-wave pseudopotentials, to calculate the structural, mechanical, thermal, electronic, and bonding properties of the cubic perovskite Pb(Mg1/3Nb2/3)O3. The results are compared with those of some isostructural compounds. The optimised lattice constant agrees fairly well with the experimental value. Mechanical stability is verified for this compound. This perovskite is damage-tolerant, as it is ductile according to all indicators. The machinability level of this substance is similar to that of the well-known MAX phases. Low thermal conductivity, better thermal shock resistance, low Debye temperature, and high melting temperature of Pb(Mg1/3Nb2/3)O3 should favour its use as thermal barrier coating (TBC) material. Dual characteristics of a weak metal and a semiconductor are expected for this material. Covalent bonding is significant in this cubic perovskite. The Fermi surface is very complex and contains a Fermi pocket around each X-point.

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Defect Properties and Lithium Incorporation in Li2ZrO3

Energies ◽

10.3390/en14133963 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3963

Author(s):

Kobiny Antony Rex ◽

Poobalasuntharam Iyngaran ◽

Navaratnarajah Kuganathan ◽

Alexander Chroneos

Keyword(s):

Atomistic Simulation ◽

Density Functional ◽

Functional Theory ◽

Lithium Zirconate ◽

Simulation Based ◽

Electrochemical Devices ◽

Li Ion ◽

Cluster Energy ◽

Experimental Values ◽

Lithium Incorporation

Lithium zirconate is a candidate material in the design of electrochemical devices and tritium breeding blankets. Here we employ an atomistic simulation based on the classical pair-wise potentials to examine the defect energetics, diffusion of Li-ions, and solution of dopants. The Li-Frenkel is the lowest defect energy process. The Li-Zr anti-site defect cluster energy is slightly higher than the Li-Frenkel. The Li-ion diffuses along the c axis with an activation energy of 0.55 eV agreeing with experimental values. The most favorable isovalent dopants on the Li and Zr sites were Na and Ti respectively. The formation of additional Li in this material can be processed by doping of Ga on the Zr site. Incorporation of Li was studied using density functional theory simulation. Li incorporation is exoergic with respect to isolated gas phase Li. Furthermore, the semiconducting nature of LZO turns metallic upon Li incorporation.

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CHARGE STABILITY AND CONDUCTANCE ANALYSIS OF ANTHRACENE-BASED SINGLE ELECTRON TRANSISTOR

International Journal of Nanoscience ◽

10.1142/s0219581x13500452 ◽

2013 ◽

Vol 12 (06) ◽

pp. 1350045 ◽

Cited By ~ 14

Author(s):

ANURAG SRIVASTAVA ◽

BODDEPALLI SANTHIBHUSHAN ◽

PANKAJ DOBWAL

Keyword(s):

Coulomb Blockade ◽

Density Functional ◽

Stability Diagram ◽

Single Electron ◽

Single Electron Transistor ◽

Functional Theory ◽

Charge Stability ◽

Anthracene Molecule ◽

The Stability ◽

Experimental Values

The present paper discusses the investigation of electronic properties of anthracene-based single electron transistor (SET) operating in coulomb blockade region using Density Functional Theory (DFT) based Atomistix toolkit-Virtual nanolab. The charging energies of anthracene molecule in isolated as well as electrostatic SET environments have been calculated for analyzing the stability of the molecule for different charge states. Study also includes the analysis of SET conductance dependence on source/drain and gate potentials in reference to the charge stability diagram. Our computed charging energies for anthracene in isolated environment are in good agreement with the experimental values and the proposed anthracene SET shows good switching properties in comparison to other acene series SETs.

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Electrochemical Lithium Storage Performance of Molten Salt Derived V2SnC MAX Phase

Nano-Micro Letters ◽

10.1007/s40820-021-00684-6 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Youbing Li ◽

Guoliang Ma ◽

Hui Shao ◽

Peng Xiao ◽

Jun Lu ◽

...

Keyword(s):

Molten Salt ◽

Redox Reaction ◽

Density Functional ◽

High Rate ◽

Max Phase ◽

Molten Salt Method ◽

Lithium Storage ◽

Max Phases ◽

Storage Mechanism ◽

A Charge

AbstractMAX phases are gaining attention as precursors of two-dimensional MXenes that are intensively pursued in applications for electrochemical energy storage. Here, we report the preparation of V2SnC MAX phase by the molten salt method. V2SnC is investigated as a lithium storage anode, showing a high gravimetric capacity of 490 mAh g−1 and volumetric capacity of 570 mAh cm−3 as well as superior rate performance of 95 mAh g−1 (110 mAh cm−3) at 50 C, surpassing the ever-reported performance of MAX phase anodes. Supported by operando X-ray diffraction and density functional theory, a charge storage mechanism with dual redox reaction is proposed with a Sn–Li (de)alloying reaction that occurs at the edge sites of V2SnC particles where Sn atoms are exposed to the electrolyte followed by a redox reaction that occurs at V2C layers with Li. This study offers promise of using MAX phases with M-site and A-site elements that are redox active as high-rate lithium storage materials.

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First-principle investigations on structural, elastic, electronic and thermodynamic properties of ScX3(X = Ir,Pd,Pt and Rh) under high pressure

Modern Physics Letters B ◽

10.1142/s0217984915502012 ◽

2015 ◽

Vol 29 (32) ◽

pp. 1550201 ◽

Cited By ~ 3

Author(s):

Bao Chen ◽

Santao Qi ◽

Hongquan Song ◽

Chuanhui Zhang ◽

Jiang Shen

Keyword(s):

Density Functional Theory ◽

Thermodynamic Properties ◽

Bulk Modulus ◽

Density Functional ◽

External Pressure ◽

First Principle ◽

Zero Temperature ◽

Functional Theory ◽

Change Trend ◽

Experimental Values

In this paper, the structural, elastic, electronic and thermodynamic properties of [Formula: see text] and [Formula: see text] intermetallic compound are investigated using pseudopotential method based on density functional theory (DFT) under pressure. In this work, the calculated lattice constant and bulk modulus are in accordance with experimental values at zero temperature and zero pressure. The bulk modulus [Formula: see text], shear modulus [Formula: see text] and Young’s modulus [Formula: see text] for [Formula: see text] and [Formula: see text] increase with the increasing external pressure. It is noted that [Formula: see text] of investigated compound has the largest [Formula: see text], [Formula: see text] and [Formula: see text]. The results of [Formula: see text] and [Formula: see text] have the same change trend, but [Formula: see text] presents an irregular change for [Formula: see text] and [Formula: see text]. The density of states for [Formula: see text] and [Formula: see text] are investigated at 0, 30 and 50 GPa. In addition, the thermodynamic properties as a function of temperature at different pressure are also studied.

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Structural, elastic, electronic and thermal properties of InAs: A study of functional density

Revista Facultad de Ingeniería ◽

10.19053/01211129.v26.n46.2017.7320 ◽

2017 ◽

Vol 26 (46) ◽

Author(s):

Víctor Mendoza-Estrada ◽

Melissa Romero-Baños ◽

Viviana Dovale-Farelo ◽

William López-Pérez ◽

Álvaro González-García ◽

...

Keyword(s):

Thermal Properties ◽

Density Functional ◽

Experimental Studies ◽

Debye Model ◽

Band Gap Energy ◽

Functional Theory ◽

Zinc Blende ◽

The Density Functional Theory ◽

The Stability ◽

Experimental Values

In this research, first-principles calculations were carried out within the density functional theory (DFT) framework, using LDA and GGA, in order to study the structural, elastic, electronic and thermal properties of InAs in the zinc-blende structure. The results of the structural properties (a, B0, ) agree with the theoretical and experimental results reported by other authors. Additionally, the elastic properties, the elastic constants (C11, C12 and C44), the anisotropy coefficient (A) and the predicted speeds of the sound ( , , and ) are in agreement with the results reported by other authors. In contrast, the shear modulus (G), the Young's modulus (Y) and the Poisson's ratio (v) show some discrepancy with respect to the experimental values, although, the values obtained are reasonable. On the other hand, it is evident the tendency of the LDA and GGA approaches to underestimate the value of the band-gap energy in semiconductors. The thermal properties (V, , θD yCV) of InAs, calculated using the quasi-harmonic Debye model, are slightly sensitive as the temperature increases. According to the stability criteria and the negative value of the enthalpy of formation, InAs is mechanically and thermodynamically stable. Therefore, this work can be used as a future reference for theoretical and experimental studies based on InAs.

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