Electronic, Optical, Mechanical and Lattice Dynamical Properties of MgBi2O6: A First-Principles Study

Electronic structure, optical, mechanical, and lattice dynamical properties of the tetragonal MgBi2O6 are studied using a first-principles method. The band gap of MgBi2O6 calculated from the PBE0 hybrid functional method is about 1.62 eV and agrees well with the experimental value. The calculations on elastic constants show that MgBi2O6 exhibits mechanical stability and strong elastic anisotropy. The detailed analysis of calculated optical parameters and effective masses clearly indicate that MgBi2O6 has strong optical response in the visible light region and high separation efficiency of photoinduced electrons and holes.

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First-Principles Study of Iron Oxide Polytypes: Comparison of GGA+Uand Hybrid Functional Method

The Journal of Physical Chemistry C ◽

10.1021/jp508096b ◽

2014 ◽

Vol 119 (1) ◽

pp. 556-562 ◽

Cited By ~ 15

Author(s):

Taedaehyeong Eom ◽

Hyung-Kyu Lim ◽

William A. Goddard ◽

Hyungjun Kim

Keyword(s):

Iron Oxide ◽

First Principles ◽

Functional Method ◽

Hybrid Functional ◽

First Principles Study

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Structural, mechanical and thermodynamic properties study on Mg–Y alloys from first-principles calculations

International Journal of Modern Physics B ◽

10.1142/s0217979220502203 ◽

2020 ◽

Vol 34 (25) ◽

pp. 2050220

Author(s):

Yingying Chen ◽

Xilong Dou ◽

Wenjie Zhu ◽

Gang Jiang ◽

Aijie Mao

Keyword(s):

Thermodynamic Properties ◽

First Principles ◽

Mechanical Stability ◽

Elastic Anisotropy ◽

Crystal Structure Analysis ◽

First Principles Calculations ◽

Phonon Spectra ◽

Volume Entropy ◽

Ductile Behavior ◽

Searching Method

The structures with different compositions of the binary Mg–Y alloys have been predicted by first-principles calculations combined with an unbiased Crystal structure Analysis by Particle Swarm Optimization (CALYPSO) structure searching method. The two already known stoichiometries alloys of Mg1Y1 with Pm-[Formula: see text] symmetry and Mg3Y1 with Fm-[Formula: see text] are confirmed, and a new stoichiometry alloy of Mg1Y3 with [Formula: see text] symmetry is proposed. The dynamical and mechanical stabilities for the three alloys at different pressures are investigated by phonon spectra and mechanical stability criteria, respectively. Subsequently, the bulk modulus, shear modulus, Young’s modulus, the brittleness/ductile behavior, the elastic anisotropy as well as Vickers hardness for the three alloys at 0 GPa are discussed in detail. The results show that the Mg1Y1, Mg3Y1 and Mg1Y3 alloys improve the hardness and stiffness compared with pure Mg, and Mg1Y3 alloy is of the best ductility in the three alloys. Meanwhile, the three alloys exhibit anisotropic. Moreover, the thermodynamic properties, such as Debye temperature, heat capacity at constant volume, entropy and Helmholtz free energy for the three stable alloys, are predicted and discussed.

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First-principles calculations of the structural, elastic, mechanical, electronic and optical properties of monoclinic Hf4CuSi4

International Journal of Modern Physics B ◽

10.1142/s0217979220500356 ◽

2020 ◽

Vol 34 (06) ◽

pp. 2050035

Author(s):

Xia Xu ◽

Wei Zeng ◽

Fu-Sheng Liu ◽

Zheng-Tang Liu ◽

Qi-Jun Liu

Keyword(s):

Optical Properties ◽

Band Structure ◽

First Principles ◽

Density Functional ◽

Mechanical Stability ◽

Elastic Anisotropy ◽

Structural Parameters ◽

Functional Theory ◽

Text Structures ◽

Structure Density

In this paper, the structural, electronic, elastic, mechanical and optical properties of monoclinic [Formula: see text] are studied using the first-principles density functional theory (DFT). The calculated structural parameters are consistent with the experimental data. The elastic constants of [Formula: see text] structures are calculated, indicating that [Formula: see text] shows mechanical stability and elastic anisotropy. According to the [Formula: see text] and Poisson’s ratio, monoclinic [Formula: see text] shows a brittle manner. The energy band structure, density of states, charge transfers and bond populations are given. And the band structure shows that the material is a metal conductor. Moreover, the optical properties and optical anisotropy of [Formula: see text] are shown and analyzed.

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First-Principles Study on III-Nitride Polymorphs: AlN/GaN/InN in the Pmn21 Phase

Materials ◽

10.3390/ma13143212 ◽

2020 ◽

Vol 13 (14) ◽

pp. 3212

Author(s):

Zheren Zhang ◽

Changchun Chai ◽

Wei Zhang ◽

Yanxing Song ◽

Linchun Kong ◽

...

Keyword(s):

Mechanical Properties ◽

Energy Band ◽

Density Functional ◽

Mechanical Stability ◽

Phonon Dispersion ◽

Elastic Anisotropy ◽

Ambient Pressure ◽

Industrial Applications ◽

Band Gaps ◽

Hybrid Functional

The structural, mechanical, and electronic properties, as well as stability, elastic anisotropy and effective mass of AlN/GaN/InN in the Pmn21 phase were determined using density functional theory (DFT). The phonon dispersion spectra and elastic constants certify the dynamic and mechanical stability at ambient pressure, and the relative enthalpies were lower than those of most proposed III-nitride polymorphs. The mechanical properties reveal that Pmn21-AlN and Pmn21-GaN possess a high Vickers hardness of 16.3 GPa and 12.8 GPa. Pmn21-AlN, Pmn21-GaN and Pmn21-InN are all direct semiconductor materials within the HSE06 hybrid functional, and their calculated energy band gaps are 5.17 eV, 2.77 eV and 0.47 eV, respectively. The calculated direct energy band gaps and mechanical properties of AlN/GaN/InN in the Pmn21 phase reveal that these three polymorphs may possess great potential for industrial applications in the future.

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Phase Stability, Elastic Modulus and Elastic Anisotropy of X Doped (X = Zn, Zr and Ag) Al3Li: Insight from First-Principles Calculations

Crystals ◽

10.3390/cryst12010007 ◽

2021 ◽

Vol 12 (1) ◽

pp. 7

Author(s):

Jinzhong Tian ◽

Yuhong Zhao ◽

Shengjie Ma ◽

Hua Hou

Keyword(s):

Phase Stability ◽

First Principles ◽

Elastic Moduli ◽

Mechanical Stability ◽

Elastic Anisotropy ◽

First Principles Calculations ◽

Stability Criteria ◽

Longitudinal Sound Velocity ◽

Positive Effect ◽

Shear Planes

In present work, the effects of alloying elements X (X = Zn, Zr and Ag) doping on the phase stability, elastic properties, anisotropy and Debye temperature of Al3Li were studied by the first-principles method. Results showed that pure and doped Al3Li can exist and be stable at 0 K. Zn and Ag elements preferentially occupy the Al sites and Zr elements tend to occupy the Li sites. All the Cij obey the mechanical stability criteria, indicating the mechanical stability of these compounds. The overall anisotropy decreases in the following order: Al23Li8Ag > Al3Li > Al23Li8Zn > Al24Li7Zr, which shows that the addition of Zn and Zr has a positive effect on reducing the anisotropy of Al3Li. The shear anisotropic factors for Zn and Zr doped Al3Li are very close to one, meaning that elastic moduli do not strongly depend on different shear planes. For pure and doped Al3Li phase, the transverse sound velocities νt1 and νt2 among the three directions are smaller than the longitudinal sound velocity νl. Moreover, only the addition of Zn is beneficial to increasing the ΘD of Al3Li among the three elements.

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First-Principles Study of the Elastic Properties of Nickel Sulfide Minerals under High Pressure

Minerals ◽

10.3390/min10090737 ◽

2020 ◽

Vol 10 (9) ◽

pp. 737 ◽

Cited By ~ 1

Author(s):

Qiuyuan Zhang ◽

Ye Tian ◽

Shanqi Liu ◽

Peipei Yang ◽

Yongbing Li

Keyword(s):

High Pressure ◽

Elastic Wave ◽

Wave Velocity ◽

Elastic Constants ◽

First Principles ◽

Nickel Sulfide ◽

Mechanical Stability ◽

Elastic Anisotropy ◽

Sulfide Minerals ◽

Changing Trends

Nickel sulfide minerals, an important type of metal sulfides, are the major component of mantle sulfides. They are also one of the important windows for mantle partial melting, mantle metasomatism, and mantle fluid mineralization. The elasticity plays an important role in understanding the deformation and elastic wave propagation of minerals, and it is the key parameter for interpreting seismic wave velocity in terms of the composition of the Earth’s interior. Based on first-principles methods, the crystal structure, equation of state, elastic constants, elastic modulus, mechanical stability, elastic anisotropy, and elastic wave velocity of millerite (NiS), heazlewoodite (Ni3S2), and polydymite (Ni3S4) under high pressure are investigated. Our calculated results show that the crystal structures of these Ni sulfides are well predicted. These Ni sulfides are mechanically stable under the high pressure of the upper mantle. The elastic constants show different changing trends with increasing pressure. The bulk modulus of these Ni sulfides increases linearly with pressure, whereas shear modulus is less sensitive to pressure. The universal elastic anisotropic index AU also shows different changing trends with pressure. Furthermore, the elastic wave velocities of Ni sulfides are much lower than those of olivine and enstatite.

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Pressure effects on structural, electronic, elastic and lattice dynamical properties of XSi2 (X = Cr, Mo, W) from first principles

International Journal of Modern Physics B ◽

10.1142/s0217979218501205 ◽

2018 ◽

Vol 32 (10) ◽

pp. 1850120 ◽

Cited By ~ 1

Author(s):

Haiyan Zhu ◽

Liwei Shi ◽

Shuaiqi Li ◽

Shaobo Zhang ◽

Wangsuo Xia

Keyword(s):

First Principles ◽

Elastic Anisotropy ◽

Structural Parameters ◽

Theoretical Data ◽

Pressure Effects ◽

Ir Absorption ◽

First Principles Calculations ◽

Energy Gaps ◽

Ir Absorption Spectra ◽

Dynamical Properties

First-principles calculations have been performed to study the structure, elastic and lattice dynamical properties of C40 XSi2 (X=Cr, Mo, W) under hydrostatic pressure. The obtained structural parameters are in line with existing experimental and theoretical data. The evolutions of fundamental bandgap energies, elastic moduli, IR absorption spectra with pressure have been investigated in detail. Our results indicate that the energy gaps of XSi2 (X=Cr, Mo, W) show different trends as the pressure increases. Larger BH/GH ratio and Poisson’s ratio are achieved with pressure, suggesting an improved ductility for XSi2 (X=Cr, Mo, W). Moreover, a large elastic anisotropy under pressure is exhibited in Young’s anisotropic factors. The infrared-active phonon frequencies exhibit substantial blueshifts under pressure.

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Structural, elastic and electronic properties of new superhard orthorhombic C28

International Journal of Modern Physics B ◽

10.1142/s0217979219502278 ◽

2019 ◽

Vol 33 (20) ◽

pp. 1950227

Author(s):

Rui Zhang ◽

Qun Wei ◽

Bing Wei ◽

Ruike Yang ◽

Ke Cheng ◽

...

Keyword(s):

Band Structure ◽

Electronic Properties ◽

Vickers Hardness ◽

First Principles ◽

Superhard Material ◽

Mechanical Stability ◽

Elastic Anisotropy ◽

First Principles Calculations ◽

Stability Criteria ◽

Imaginary Frequency

The structural, mechanical and electronic properties of recently reported superhard material C[Formula: see text] are studied by first-principles calculations. The unit cell of C[Formula: see text] is composed of 28 carbon atoms and all sp3 hybridized bonds. From 0 GPa to 100 GPa, C[Formula: see text] satisfies the mechanical stability criteria and the phonon spectrum of C[Formula: see text] has no imaginary frequency, which means that C[Formula: see text] is mechanically and dynamically stable. The results of hardness calculated show that C[Formula: see text] is a potential superhard material with the Vickers hardness of 84.0 GPa. By analyzing the elastic anisotropy, we found that elastic anisotropy of C[Formula: see text] increases with pressure. The calculations of band structure demonstrates that C[Formula: see text] is an indirect bandgap semiconductor with the gap of 4.406 eV. These analyses demonstrate C[Formula: see text] is a superhard semiconductor material.

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Physical properties of osmium dinitride with fluorite, pyrite, marcasite, and monoclinic structures under high pressure: First-principles study

Canadian Journal of Physics ◽

10.1139/cjp-2014-0228 ◽

2015 ◽

Vol 93 (4) ◽

pp. 424-433 ◽

Cited By ~ 1

Author(s):

Ni-Na Ge ◽

Yong-Kai Wei ◽

Jia-Jin Tan ◽

Guang-Fu Ji ◽

Yan Cheng

Keyword(s):

Phase Transition ◽

Thermodynamic Properties ◽

Sound Velocity ◽

First Principles ◽

Mechanical Stability ◽

Elastic Anisotropy ◽

Fluorite Structure ◽

Mechanical Anisotropy ◽

Total Density ◽

Structure Phase Transition

The structure, phase transition, elastic, and thermodynamic properties of OsN2 have been studied via first-principles calculations. It is shown that the CoSb2 structure is more stable than other structures. By the calculated H-P relations at 0 K, we found that the phase transition of OsN2 from CoSb2 structure to marcasite structure (ε → δ) occurs at 16.8 GPa, while the phase transition pressure between pyrite structure and fluorite structure (γ → α) is 80 GPa. The results of obtained phase transitions are also confirmed by bond length, sound velocity, and thermal expansion coefficient under different pressures. The pressure dependences of the elastic constants, mechanical stability, and mechanical anisotropy of four structures of OsN2 have been investigated by finding that the fluorite (pyrite and marcasite) structure OsN2 is mechanically stable under hydrostatic pressure (up to 60 GPa). However, the monoclinic structure is mechanically unstable under pressure from 0 to 60 Gpa. The calculated elastic anisotropic factors show that OsN2 possesses high elastic anisotropy under pressure. Moreover, the calculations on total density of states show that OsN2 of different structures has a metallic character, in agreement with previous theoretical results. The thermodynamic properties and sound velocity under diverse pressures of OsN2 of the four structures have been also investigated successfully.

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Novel structural phases and the properties of LaX (X = P, As) under high pressure: first-principles study

RSC Advances ◽

10.1039/d0ra09238j ◽

2021 ◽

Vol 11 (5) ◽

pp. 3058-3070

Author(s):

Yu Zhou ◽

Lan-Ting Shi ◽

A-Kun Liang ◽

Zhao-Yi Zeng ◽

Xiang-Rong Chen ◽

...

Keyword(s):

Phase Transition ◽

High Pressure ◽

Thermodynamic Properties ◽

First Principles ◽

Electronic Structures ◽

Pressure Range ◽

Mechanical Stability ◽

First Principles Study

The structures, phase transition, mechanical stability, electronic structures, and thermodynamic properties of lanthanide phosphates (LaP and LaAs) are studied in the pressure range of 0 to 100 GPa by first principles.

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