Phase stability comparison by first principle calculation and experimental observation of microstructure evolution in a Mg–6Gd–2Zn(wt%) alloy

2010 ◽  
Vol 527 (10-11) ◽  
pp. 2643-2648 ◽  
Author(s):  
L. Lin ◽  
P. Liang ◽  
L. Yang ◽  
L.J. Chen ◽  
Z. Liu ◽  
...  
Keyword(s):  
Experimental Observation ◽  
Microstructure Evolution ◽  
Phase Stability ◽  
First Principle ◽  
Principle Calculation ◽  
First Principle Calculation

First Principle Calculation of Li2Fe0.5Cr0.5SiO4 for Li-Ion Battery Cathode

2015 ◽  
Vol 1112 ◽  
pp. 286-289
Author(s):  
Ganjar Kurniawan Sukandi ◽  
Triati Dewi Kencana Wungu ◽  
Ferry Iskandar
Keyword(s):  
Structural Change ◽  
Phase Stability ◽  
Density Functional ◽  
Positive Sign ◽  
Initial Structure ◽  
First Principle ◽  
Generalized Gradient ◽  
Principle Calculation ◽  
First Principle Calculation ◽  
Couple Reaction

First principle calculation based on Density Functional Theory and U correction (DFT+U) is used to investigate structural change while losing Li atom, average voltage for couple reaction, phase stability, and electronic structure of Li2Fe0.5Cr0.5SiO4. In this calculation, generalized gradient approach (GGA) of Perdew-Burke-Ernzerhof (PBE) is used for exchange-correlation functional. The initial structure of Li2Fe0.5Cr0.5SiO4 is obtained from the pmn21 structure of Li2FeSiO4 and then the Fe site is substituted by 50 % of Cr. The results of calculation show that the optimized Li2Fe0.5Cr0.5SiO4 has a monoclinic structure, which has little different with Li2FeSiO4 structure. Although the delithiated system (LiFe0.5Cr0.5SiO4) is taken into consideration, the structural geometry does not change significantly. It is indicated that the presence of Cr does not affect to the property of structural change. From the density of states (DOS) analysis, the presence of Cr causes the width of band gap become decrease. Therefore, the electronic properties change from insulator to semiconductor-like behavior. Average voltage for couple reaction M+2/ M+3 of Li2Fe0.5Cr0.5SiO4 is about 3.05 V which is lower than Li2FeSiO4. Furthermore, the formation energy for Li2Fe0.5Cr0.5SiO4 and all delithiation have a relatively positive sign compared with Li2FeSiO4 that mean that they have poor phase stability than Li2FeSiO4.

A combined study of thermodynamic and first-principle calculation for single bond energy of Cu clusters

2019 ◽  
Vol 125 (9) ◽  
pp. 094302
Author(s):  
H. Li ◽  
H. N. Du ◽  
X. W. He ◽  
Y. Y. Shen ◽  
H. X. Zhang ◽  
...  
Keyword(s):  
Bond Energy ◽  
First Principle ◽  
Single Bond ◽  
Principle Calculation ◽  
First Principle Calculation

First-Principle Calculation on Misfit Layered Cobaltite and La-Doped Series

2013 ◽  
Vol 652-654 ◽  
pp. 554-558
Author(s):  
Xin Min Min ◽  
Xuchao Wang
Keyword(s):  
Thermoelectric Property ◽  
Variation Method ◽  
First Principle ◽  
Direct Relation ◽  
Discrete Variation ◽  
Principle Calculation ◽  
First Principle Calculation ◽  
Binary Oxides ◽  
La Doped ◽  
Layered Cobaltite

The relations between electronic structure and thermoelectric property of misfit layered cobaltite of Ca3Co4O9 and La-doped series are studied from the calculation by density function and discrete variation method (DFT-DVM). The highest valence band (HVB) and the lowest conduction band (LCB) near Fermi level are only mainly from O 2p and Co 3d in Ca2CoO3 layer. Therefore, the semiconductor, or thermoelectric property of Ca3Co4O9 should be mainly from Ca2CoO3 layer, but have no direct relation to the CoO2 layer, which is consistent with that binary oxides hardly have thermoelectric property, but trinary oxide compounds have quite good thermoelectric property. With the amount of La-doped increase, the gap between HVB and LCB firstly decrease, then reaches the minimum, finally increase. The gap affects the thermoelectric property. Therefore, there is a best amount of Na-doped to improve thermoelectric property, which is consistent with the experiment.

First-Principle Calculation of Al2O3(012)/SiC(310) Interface Model

2017 ◽  
Vol 896 ◽  
pp. 120-127 ◽  
Author(s):  
Ting Ting Zhou ◽  
Chuan Zhen Huang ◽  
Ming Dong Yi
Keyword(s):  
Grain Boundary ◽  
Population Analysis ◽  
First Principle ◽  
Interface Model ◽  
Electronic Density ◽  
Principle Calculation ◽  
First Principle Calculation ◽  
Multi Phase ◽  
Relationship Of ◽  
Interface Bonding Strength

First-principle calculation is carried out on Al2O3(012)/SiC(310) interface model. It can be concluded from the electronic density and population analysis that Al-C and O-Si located at grain boundary primarily contribute to the interface bonding strength and creep resistance property. The electronic charges in grain boundaries and grains are compared with each other. And the valence electrons are found to be redistributed. The relationship of all kinds of chemical bonds in grains and grain boundary of the interface model is analyzed. Also the toughening mechanism of Al2O3/SiC multi-phase ceramic tool materials is explained in nano-scale.

A Study on First Principle Calculation of Alloy Phase Diagram by Monte Carlo Simulation

1992 ◽  
Vol 291 ◽  
Author(s):  
Hideaki Sawada ◽  
Atsushi Nogami ◽  
Wataru Yamada ◽  
Tooru Matsiuniya
Keyword(s):  
Phase Diagram ◽  
Monte Carlo ◽  
Alloy Phase Diagram ◽  
Lattice Constant ◽  
Local Concentration ◽  
First Principle ◽  
Principle Calculation ◽  
First Principle Calculation ◽  
Local Lattice ◽  
Mc Simulation

ABSTRACTA method of first principle calculation of alloy phase diagram was developed by the combination of first principle energy band calculation, cluster expansion method (CEM) and Monte Carlo (MC) simulation, where the effective multi-body potential energy for the flip test in MC simulation was obtained by the decomposition of the total energy by CEM. This method was applied to Cu-Au binary system. The calculated phase diagram agreed with that of CVM by introducing the dependence of the lattice constant on the concentration of the whole system. Furthermore an attempt of introducing the effect of local lattice relaxation was performed by the consideration of the local concentration. The order-disorder transition temperature became closer to the experimental value by adjustment of the local lattice constant depending on the concentration in the local region consisted of up to the second nearest neighbors of the atom tested for flipping.

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