scholarly journals First-principles calculations of high-pressure physical properties anisotropy for magnesite

2021 ◽  
Author(s):  
Zi-Jiang Liu ◽  
Xiao-Wei Sun ◽  
Cai-Rong Zhang ◽  
Shun-Jing Zhang ◽  
Zheng-Rong Zhang ◽  
...  
Keyword(s):  
High Pressure ◽  
Thermal Expansion ◽  
Physical Properties ◽  
Wave Velocity ◽  
First Principles ◽  
Elastic Moduli ◽  
First Principles Calculations ◽  
Research Results ◽  
Velocity Anisotropy ◽  
Mechanical Hardness

Abstract The first-principles calculations based on density functional theory with projector-augmented wave are used to study the anisotropy of elastic modulus, mechanical hardness, minimum thermal conductivity, acoustic velocity and thermal expansion of magnesite(MgCO3) under deep mantle pressure. The calculation results of the phase transition pressure, equation of state, elastic constants, elastic moduli, elastic wave velocities and thermal expansion coefficient are consistent with those determined experimentally. The research results show that the elastic moduli have strong anisotropy, the mechanical hardness gradually softens with increasing pressure, the conduction velocity of heat in the [100] direction is faster than that in the [001] direction, the plane wave velocity anisotropy first increases and then gradually decreases with increasing pressure, and the shear wave velocity anisotropy increases with the increase of pressure, the thermal expansion in the [100] direction is greater than that in the [001] direction. The research results are of great significance to people's understanding of the high-pressure physical properties of carbonates in the deep mantle.

scholarly journals First-Principles Calculations of High-Pressure Physical Properties of Ti0.5Ta0.5 Alloy

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 796
Author(s):  
Fang Yu ◽  
Yu Liu
Keyword(s):  
High Pressure ◽  
Physical Properties ◽  
First Principles ◽  
Theoretical Study ◽  
Applied Pressure ◽  
Lattice Parameter ◽  
Physical Parameters ◽  
First Principles Calculations ◽  
Analysis Method ◽  
Metallic Bond

In this paper, an in-depth theoretical study on some physical properties of Ti0.5Ta0.5 alloy with systematic symmetry under high pressure is conducted via first-principles calculations, and relevant physical parameters are calculated. The results demonstrate that the calculated parameters, including lattice parameter, elastic constants, and elastic moduli, fit well with available theoretical and experimental data when the Ti0.5Ta0.5 alloy is under T = 0 and P = 0 , indicating that the theoretical analysis method can effectively predict the physical properties of the Ti0.5Ta0.5 alloy. The microstructure and macroscopic physical properties of the alloy cannot be destroyed as the applied pressure ranges from 0 to 50GPa, but the phase transition of crystal structure may occur in the Ti0.5Ta0.5 alloy if the applied pressure continues to increase according to the TDOS curves and charge density diagram. The value of Young’s and shear modulus is maximized at P = 25   GPa . The anisotropy factors A ( 100 ) [ 001 ] and A ( 110 ) [ 001 ] are equal to 1, suggesting the Ti0.5Ta0.5 alloy is an isotropic material at 28 GPa, and the metallic bond is strengthened under high pressure. The present results provide helpful insights into the physical properties of Ti0.5Ta0.5 alloy.

Structural and Physical Properties of ZrSi2 under High Pressure: Experimental Study and First-Principles Calculations

2018 ◽  
Vol 58 (1) ◽  
pp. 405-410 ◽  
Author(s):  
Haihua Chen ◽  
Hao Liang ◽  
Fang Peng ◽  
Huishan Li ◽  
Bin Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Physical Properties ◽  
First Principles ◽  
First Principles Calculations

First-Principles Investigations on Structural, Elastic, and Thermodynamic Properties of Ce-La Alloys Under High Pressure

2014 ◽  
Vol 69 (1-2) ◽  
pp. 52-60
Author(s):  
Li-Qin Zhang ◽  
Yan Cheng ◽  
Zhen-Wei Niu ◽  
Guang-Fu Ji
Keyword(s):  
Heat Capacity ◽  
High Pressure ◽  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Electronic Properties ◽  
Ground State ◽  
First Principles ◽  
Debye Model ◽  
First Principles Calculations ◽  
Charge Densities

The structural stability, thermodynamic, elastic, and electronic properties of cerium (Ce)- lanthanum (La) alloys were investigated for different Ce/La ratios under pressure by first-principles calculations using on-the-fly (OTF) pseudopotential and general gradient approximation (GGA). The ground-state properties of lanthanum and cerium obtained by minimizing the total energy agree favourably with other work.We derived the elastic constants, bulk modulus, and shear modulus of the La-Ce alloys for different Ce/La ratios. Using the quasi-harmonic Debye model, the thermodynamic properties of the La-Ce alloys including the thermal expansion coefficient α and heat capacity Cv are successfully obtained in the temperature range from 0 K to 1000 K. Furthermore, the electronic properties such as density of states and charge densities were also studied.

Phase Transition and ThermodynamicProperties of OsN2 under High Pressure

2013 ◽  
Vol 401-403 ◽  
pp. 660-662
Author(s):  
Zhi Jian Fu ◽  
Li Jun Jia ◽  
Wei Long Quan
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Thermal Expansion ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Fluorite Structure ◽  
First Principles Calculations ◽  
Zero Temperature

The lattice parameters, phase transition, and thermodynamic properties of OsN2in pyrite and fluorite structure are investigated by first-principles calculations. The pressure and temperature induced phase transitions of OsN2from fluorite structure to pyrite structure have been obtained. It is found that the transition pressure of OsN2at zero temperature is 158.2 GPa, and there exists no transition temperature. In addition, the thermal expansion, the Debye temperature, and the Grüneisen parameter in diverse pressures and temperatures about these two structures have also been obtained. Key words: transition phase; thermodynamic properties; OsN2PACS numbers: 71.15.Mb, 64.70.Kb

scholarly journals Structural and physical properties of 99 complex bulk chalcogenides crystals using first-principles calculations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sahib Hasan ◽  
Khagendra Baral ◽  
Neng Li ◽  
Wai-Yim Ching
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
First Principles ◽  
Experimental Studies ◽  
First Principles Calculations ◽  
Chalcogenide Semiconductors ◽  
Optical And Mechanical Properties ◽  
Very Large Database ◽  
Unique Composition ◽  
Fundamental Physical

AbstractChalcogenide semiconductors and glasses have many applications in the civil and military fields, especially in relation to their electronic, optical and mechanical properties for energy conversion and in enviormental materials. However, they are much less systemically studied and their fundamental physical properties for a large class chalcogenide semiconductors are rather scattered and incomplete. Here, we present a detailed study using well defined first-principles calculations on the electronic structure, interatomic bonding, optical, and mechanical properties for 99 bulk chalcogenides including thirteen of these crytals which have never been calculated. Due to their unique composition and structures, these 99 bulk chalcogenides are divided into two main groups. The first group contains 54 quaternary crystals with the structure composition (A2BCQ4) (A = Ag, Cu; B = Zn, Cd, Hg, Mg, Sr, Ba; C = Si, Ge, Sn; Q = S, Se, Te), while the second group contains scattered ternary and quaternary chalcogenide crystals with a more diverse composition (AxByCzQn) (A = Ag, Cu, Ba, Cs, Li, Tl, K, Lu, Sr; B = Zn, Cd, Hg, Al, Ga, In, P, As, La, Lu, Pb, Cu, Ag; C = Si, Ge, Sn, As, Sb, Bi, Zr, Hf, Ga, In; Q = S, Se, Te; $$\hbox {x} = 1$$ x = 1 , 2, 3; $$\hbox {y} = 0$$ y = 0 , 1, 2, 5; $$\hbox {z} = 0$$ z = 0 , 1, 2 and $$\hbox {n} = 3$$ n = 3 , 4, 5, 6, 9). Moreover, the total bond order density (TBOD) is used as a single quantum mechanical metric to characterize the internal cohesion of these crystals enabling us to correlate them with the calculated properties, especially their mechanical properties. This work provides a very large database for bulk chalcogenides crucial for the future theoretical and experimental studies, opening opportunities for study the properties and potential application of a wide variety of chalcogenides.

scholarly journals Mechanical properties and band structure of CdSe and CdTe nanostructures at high pressure - a first-principles study

2019 ◽  
Vol 13 (2) ◽  
pp. 124-131 ◽  
Author(s):  
Natarajan Kishore ◽  
Veerappan Nagarajan ◽  
Ramanathan Chandiramouli
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Shear Modulus ◽  
Band Structure ◽  
First Principles ◽  
Pressure Range ◽  
Uniaxial Pressure ◽  
First Principles Calculations ◽  
Zinc Blende ◽  
Cauchy Pressure

First-principles calculations for CdSe and CdTe nanostructures were carried out to study their mechanical properties and band structure under the uniaxial pressure range of 0 to 50GPa. It was presumed that the CdSe and CdTe nanostructures exist in the zinc-blende phase under high pressure. The mechanical properties, such as elastic constants, bulk modulus, shear modulus and Young?s modulus, were explored. Furthermore, Cauchy pressure, Poisson?s ratio and Pugh?s criterion were studied under high pressure for both CdSe and CdTe nanostructures, and the results show that they exhibit ductile property. The band structure studies of CdSe and CdTe were also investigated. The findings show that the mechanical properties and the band structures of CdSe and CdTe can be tailored with high pressure.

COMPARATIVE STUDY OF THE STRUCTURAL AND ELECTRONIC PROPERTIES OF BN(5, 5) AND C(5, 5) NANOTUBES UNDER PRESSURE

2010 ◽  
Vol 24 (24) ◽  
pp. 4851-4859
Author(s):  
KAIHUA HE ◽  
GUANG ZHENG ◽  
GANG CHEN ◽  
QILI CHEN ◽  
MIAO WAN ◽  
...  
Keyword(s):  
High Pressure ◽  
Comparative Study ◽  
Charge Density ◽  
Band Gap ◽  
Electronic Properties ◽  
Cross Section ◽  
First Principles ◽  
First Principles Calculations ◽  
Zinc Blende ◽  
Structural And Electronic Properties

The structural and electronic properties of BN(5, 5) and C(5, 5) nanotubes under pressure are studied by using first principles calculations. In our study range, BN(5, 5) undergoes obvious elliptical distortion, while for C(5, 5) the cross section first becomes an ellipse and then, under further pressure, is flattened. The band gap of BN(5, 5) decreases with increasing pressure, which is inverse to that of zinc blende BN, whereas for C(5, 5) the metallicity is always preserved under high pressure. The population of charge density indicates that intertube bonding is formed under pressure. We also find that BN(5, 5) may collapse, and a new polymer material based on C(5, 5) is formed by applying pressure.

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