scholarly journals First-principles calculations of mechanical and thermodynamic properties of tetragonal Be12Ti

RSC Advances ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 5302-5312 ◽  
Author(s):  
Xiankun Liu ◽  
Qijie Feng ◽  
Bin Tang ◽  
Jian Zheng ◽  
Zhou Zheng ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermodynamic Properties ◽  
Plane Wave ◽  
First Principles ◽  
Harmonic Approximation ◽  
First Principles Calculations ◽  
High Temperature And Pressure ◽  
Temperature And Pressure

The elastic and thermodynamic properties of tetragonal Be12Ti under high temperature and pressure are investigated by first-principles calculations based on pseudopotential plane-wave DFT within the GGA and quasi-harmonic approximation (QHA).

scholarly journals First Principles Calculations on Elastic, Thermodynamic and Electronic Properties of Co2Zr and Co2Ti at High Temperature and Pressure

2020 ◽  
Vol 10 (6) ◽  
pp. 2097
Author(s):  
Mi-An Xue ◽  
Xiaoli Yuan ◽  
Cheng Zhong ◽  
Peng Wan
Keyword(s):  
High Temperature ◽  
Electronic Properties ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Debye Model ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
High Temperature And Pressure ◽  
Temperature And Pressure

Co2Zr and Co2Ti are both cubic crystals with a Cu2Mg-type structure. The elastic, thermodynamic and electronic properties of the intermetallic compounds Co2Zr and Co2Ti are investigated by using ab initio plane-wave pseudopotential density functional theory (PWPDFT) and generalized gradient approximation (GGA) under high temperature and pressure. The partially calculated results are consistent with the available experimental data. The elastic properties of Co2Zr and Co2Ti under high pressure were first studied by first principles calculations. The results indicate that the elastic constants, elastic modulus and Poisson’s ratio are functions of pressure, indicating that the effect of pressure on the ductility and anisotropy is significant. The thermodynamic properties are also calculated by the quasi-harmonic Debye model. In the range of 0~100 GPa pressure and 0~1500 K temperature, the Debye temperature Θ, the heat capacity CV and the thermal expansion α vary with pressure and temperature. Co2Ti has a higher Debye temperature than Co2Zr under the same pressure. Decreasing temperature and increasing pressure have the same effects on CV and α. The electron density difference and density of states of Co2Zr and Co2Ti are finally investigated. The results show that both Co2Zr and Co2Ti are typically metal crystals but Co2Zr has greater covalence than Co2Ti.

Using First Principles Thermodynamics to Predict the Shape Surface Structure and Reactivity of Solvated Nanoparticles at High Temperatures and Pressures.

2013 ◽  
Vol 1546 ◽  
Author(s):  
Christopher J. O’Brien ◽  
Donald W. Brenner
Keyword(s):  
First Principles ◽  
Nanoparticle Synthesis ◽  
Surface Reactivity ◽  
Chemical Processes ◽  
First Principles Calculations ◽  
Chemical Potentials ◽  
High Temperature And Pressure ◽  
Bulk Thermodynamics ◽  
Pressure Water ◽  
Temperature And Pressure

ABSTRACTHydrothermal nanoparticle synthesis uses high temperature and pressure water to control the chemical processes that lead to specific compositions and structures. Analyses of the chemistry associated with this process have been mainly restricted to bulk thermodynamics in the form of quantities such as solubilities and empirical models based on experimental observations. In this paper we demonstrate for NiO and NiFe2O4 particles how effective reference chemical potentials derived from first principles calculations can be used to predict cluster shapes, nucleation barriers and surface reactivity. Implications for controlling the nanoparticle size and shape by adjusting pH and temperature will be discussed, as well as implications of these results in forming nanostructured materials by cluster condensation.

First-Principles Calculations of Elastic and Thermodynamic Properties of Cubic CdTe

2011 ◽  
Vol 268-270 ◽  
pp. 886-891
Author(s):  
Ben Hai Yu ◽  
Dong Chen
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
First Principles ◽  
Debye Model ◽  
First Principles Calculations ◽  
Lattice Constants ◽  
Temperature And Pressure ◽  
The Relationship

the equilibrium lattice constants, elastic and thermodynamic properties of cubic CdTe are systemically investigated at high temperature using the plane-wave pseudopotential method as well as the quasi-harmonic Debye model. The bulk modulus of CdTe are calculated as a function of temperature up to 1000K, the relationship between bulk modulusBand pressure is also obtained. The results gained from this model will provide overall predictions accurately for the temperature and pressure dependence of various quantities such as the bulk modulus, the heat capacity and the thermal expansion coefficient. More over, the dependences between Debye temperature and temperature are also successfully obtained. Our results are compared with the experimental data and discussed in light of previous works.

First-Principles Investigation of Structural Stability, Mechanical, Anisotropic, and Thermodynamic Properties of CeT2Al20 Intermetallics

2018 ◽  
Vol 73 (12) ◽  
pp. 1157-1167 ◽  
Author(s):  
He Ma ◽  
Xiaoyou Li ◽  
Wei Jiang ◽  
Xudong Zhang
Keyword(s):  
High Temperature ◽  
Thermodynamic Properties ◽  
Thermodynamic Parameters ◽  
Structural Stability ◽  
Elastic Constants ◽  
First Principles ◽  
Elastic Moduli ◽  
Formation Enthalpy ◽  
First Principles Calculations ◽  
Acoustic Velocities

AbstractFirst-principles calculations were carried out to explore the structural stability, elastic moduli, ductile or brittle behaviour, anisotropy, dynamical stability, and thermodynamic properties of pure Al and CeT2Al20 (T = Ti, V, Cr, Nb, and Ta) intermetallics. The calculated formation enthalpy and phonon frequencies confirm that these intermetallics satisfy the conditions for structural stability. The elastic constants Cij, elastic moduli B, G, and E, and the hardness Hv indicate these intermetallics have higher hardness and the better resistance against deformation than pure Al. The values of Poisson’s ratio (v) and B/G indicate that CeT2Al20 intermetallics are all brittle materials. The anisotropic constants and acoustic velocities confirm that CeT2Al20 intermetallics are all anisotropic, but CeV2Al20, CeNb2Al20, and CeTa2Al20 are nearly isotropic. Importantly, the calculated thermodynamic parameters show that CeT2Al20 intermetallics exhibit better thermodynamic properties than pure Al at high temperature.

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