FIRST-PRINCIPLES CALCULATION OF LEAD-FREE PEROVSKITE SnTiO3

2013 ◽  
Vol 27 (24) ◽  
pp. 1350144 ◽  
Author(s):  
HONGJUN YE ◽  
RUIZHI ZHANG ◽  
DAWEI WANG ◽  
YU CUI ◽  
JIE WEI ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Piezoelectric Materials ◽  
First Principles Calculation ◽  
Lead Free ◽  
Structure Stability ◽  
Functional Theory ◽  
Phonon Spectra ◽  
Sn Substitution

The phonon spectra, band structure and density of states of cubic perovskite SnTiO 3 were investigated using first-principles density functional theory (DFT) computation. The potential energy curves of cations displacement and the formation energy of Sn substitution to B-site were calculated to estimate the structure stability. The results indicate that perovskite SnTiO 3 is a promising ferroelectric end member for lead-free piezoelectric materials and applications.

First-Principles Calculation of Defect Formation and Positron Annihilation States in Bi2Te3

2017 ◽  
Vol 373 ◽  
pp. 41-45 ◽  
Author(s):  
Bin Zhao ◽  
Bo Zhou ◽  
Chong Yang Li ◽  
Ning Qi ◽  
Zhi Quan Chen
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Defect Formation ◽  
First Principles Calculation ◽  
Functional Theory ◽  
Rich Condition ◽  
The Density Functional Theory ◽  
Positron Wave Function ◽  
Positron Lifetimes

Defect formation energy in Bi2Te3 thermoelectric material was calculated using a first principles approach based on the Density Functional Theory (DFT). For vacancy-type defect, the Te1 vacancy (VTe1) is the most stable defect with low formation energy in both Bi-rich and Te-rich conditions, which indicates that the Te1 vacancies have higher probability to be formed. For antisite defects, the formation energy of BiTe1 is much lower than that of BiTe2 in Bi-rich condition, while in Te-rich condition it is beneficial for TeBi with lower formation energy. Positron wave function distribution and positron lifetimes of different annihilation states in Bi2Te3 were also calculated using the atomic superposition (ATSUP) method. The positron bulk lifetime in Bi2Te3 is about 231 ps, and for the neutral vacancy-type defects without relaxation, the positron lifetimes of VBi, VTe1 and VTe2 are 275 ps, 295 ps and 269 ps, respectively.

scholarly journals Bi2Te3 single crystals with high room-temperature thermoelectric performance enhanced by manipulating point defects based on first-principles calculation

RSC Advances ◽  
2019 ◽  
Vol 9 (25) ◽  
pp. 14422-14431 ◽  
Author(s):  
Chunmei Tang ◽  
Zhicheng Huang ◽  
Jun Pei ◽  
Bo-Ping Zhang ◽  
Peng-Peng Shang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Single Crystals ◽  
Point Defects ◽  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Room Temperature ◽  
First Principles Calculation ◽  
Functional Theory

This study prepared Bi2Te3 single crystals and investigated the thermoelectric properties of Bi2Te3 based on the electronic structure and formation energy of point defects which are calculated by density functional theory.

scholarly journals Strain Conditions for the Inverse Heusler Type Fully Compensated Spin-Gapless Semiconductor Ti2MnAl: A First-Principles Study

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2091 ◽  
Author(s):  
Tie Yang ◽  
Liyu Hao ◽  
Rabah Khenata ◽  
Xiaotian Wang
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Debye Model ◽  
Pressure Effects ◽  
First Principles Calculation ◽  
Strain Condition ◽  
Functional Theory ◽  
Future Work

In this work, we systematically studied the structural, electronic, magnetic, mechanical and thermodynamic properties of the fully compensated spin-gapless inverse Heusler Ti2MnAl compound under pressure strain condition by applying the first-principles calculation based on density functional theory and the quasi-harmonic Debye model. The obtained structural, electronic and magnetic behaviors without pressure are well consistent with previous studies. It is found that the spin-gapless characteristic is destroyed at 20 GPa and then restored with further increase in pressure. While, the fully compensated ferromagnetism shows a better resistance against the pressure up to 30 GPa and then becomes to non-magnetism at higher pressure. Tetragonal distortion has also been investigated and it is found the spin-gapless property is only destroyed when c/a is less than 1 at 95% volume. Three independent elastic constants and various moduli have been calculated and they all show increasing tendency with pressure increase. Additionally, the pressure effects on the thermodynamic properties under different temperature have been studied, including the normalized volume, thermal expansion coefficient, heat capacity at constant volume, Grüneisen constant and Debye temperature. Overall, this theoretical study presents a detailed analysis of the physical properties’ variation under strain condition from different aspects on Ti2MnAl and, thus, can provide a helpful reference for the future work and even inspire some new studies and lead to some insight on the application of this material.

Effect of Alloying Elements V, Cr and Ni on the Electronic Structure and Mechanical Properties of FeAl from First-Principles Calculation

2014 ◽  
Vol 887-888 ◽  
pp. 378-383 ◽  
Author(s):  
Yu Chen ◽  
Zheng Jun Yao ◽  
Ping Ze Zhang ◽  
Dong Bo Wei ◽  
Xi Xi Luo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electronic Structure ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Valence Bond ◽  
Ternary Alloys ◽  
First Principles Calculation ◽  
Structure Stability ◽  
Alloying Element

The structure stability, mechanical properties and electronic structures of B2 phase FeAl intermetallic compounds and FeAl ternary alloys containing V, Cr or Ni were investigated using first-principles density functional theory calculations. Several models are established. The total energies, cohesive energies, lattice constants, elastic constants, density of states, and the charge densities of Fe8Al8 and Fe8XAl7 ( X=V, Cr, Ni ) are calculated. The stable crystal structures of alloy systems are determined due to the cohesive energy results. The calculated lattice contants of Fe-Al-X ( X= V, Cr, Ni) were found to be related to the atomic radii of the alloy elements. The calculation and analysis of the elastic constants showed that ductility of FeAl alloys was improved by the addition of V, Cr or Ni, the improvement was the highest when Cr was used. The order of the ductility was as follows: Fe8CrAl7 > Fe8NiAl7 > Fe8VAl7 > Fe8Al8. The results of electronic structure analysis showed that FeAl were brittle, mainly due to the orbital hybridization of the s, p and d state electron of Fe and the s and p state electrons of Al, showing typical characteristics of a valence bond. Micro-mechanism for improving ductility of FeAl is that d orbital electron of alloying element is maily involved in hybridization of FeAl, alloying element V, Cr and Ni decrease the directional property in bonding of FeAl.

Bandgap control and optical properties of β-Si3N4 by single- and co-doping from a first-principles simulation

2018 ◽  
Vol 32 (14) ◽  
pp. 1850178 ◽  
Author(s):  
Xuefeng Lu ◽  
Xu Gao ◽  
Junqiang Ren ◽  
Cuixia Li ◽  
Xin Guo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Blue Shift ◽  
Functional Theory ◽  
Co Doping ◽  
Charge Density Difference ◽  
Co Doped

Bandgap tailoring of [Formula: see text]-Si3N4 is performed by single and co-doping by using density functional theory (DFT) of PBE functional and plane-wave pseudopotential method. The results reveal that a direct bandgap transfers into an indirect one when single-doped with As element. Also, a considerate decrease of bandgap to 0.221 eV and 0.315 eV is present for Al–P and As–P co-doped systems, respectively, exhibiting a representative semiconductor property that is characteristic for a narrower bandgap. Compared with other doped systems, Al-doped system with formation energy of 2.67 eV is present for a more stable structure. From charge density difference (CDD) maps, it is found that the blue area between co-doped atoms increases, illustrating an enhancement of covalent property for Al–P and Al–As bonds. Moreover, a slightly obvious “Blue shift” phenomenon can be obtained in Al, Al–P and Al–As doped systems, indicating an enhanced capacity of responses to light, which contributes to the insight for broader applications with regard to photoelectric devices.

First-Principles Calculation of Water Molecules with Adsorbed Ions on the Fe(001) Surface

2010 ◽  
Vol 654-656 ◽  
pp. 1662-1665
Author(s):  
Norio Nunomura ◽  
Satoshi Sunada
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Dissociative Adsorption ◽  
First Principles Calculation ◽  
Water Molecules ◽  
Metal Interface ◽  
Functional Theory ◽  
Atomic Orbitals ◽  
Adsorption Structure ◽  
Valence Electrons

The behavior of water molecules with sulfate on the Fe(001) surface has been investigated using a first-principles method based on density-functional theory (DFT) with numerical atomic orbitals as basis functions for the description of valence electrons and nonlocal pseudopotentials for the atomic core. We present results for the adsorption structure and the bonding nature as caused by the adsorption-induced variations in the electron density and the projected density of states. We have found that the structure of absorbed sulfate depends on the coverage of water molecule on the surface. Analysis of electrostatic potential at an aqueous metal interface provides an appropriate framework to understand complicated potential structures. The mechanism of proton transfer through dissociative adsorption and hydrogen bonding of water molecules has been obtained from calculated results.

THE Ge(001) SURFACE RECONSTRUCTION: DFT AND MCS

1999 ◽  
Vol 06 (06) ◽  
pp. 1045-1051 ◽  
Author(s):  
YOSHIHIDE YOSHIMOTO ◽  
YOSHIMICHI NAKAMURA ◽  
HIROSHI KAWAI ◽  
MASARU TSUKADA ◽  
MASATOSHI NAKAYAMA
Keyword(s):  
Phase Transition ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Transient Temperature ◽  
Diffraction Experiment ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Flip Flop ◽  
X Ray

The problem of relative energetic stabilities of the high order reconstructions of the Ge(001) surface is revisited by a more refined first-principles calculation based on density functional theory. Using this result, we performed a Monte Carlo simulation of the phase transition, and obtained 315 K as the transition temperature of p(2× 1) → c(4× 2). This reproduces fairly well the transient temperature (250–350 K) observed by an X-ray diffraction experiment. The obtained geometry of the c(4× 2) structure compares well with an X-ray diffraction experiment. The potential energy curves of flip-flop motions of both single dimer and dimer in type-P defect are also obtained.

First principles study of the adsorption and dissociation mechanisms of H2S on a TiO2anatase (001) surface

RSC Advances ◽  
2016 ◽  
Vol 6 (10) ◽  
pp. 7941-7949 ◽  
Author(s):  
Naeem Shahzad ◽  
Akhtar Hussain ◽  
Naeem Mustafa ◽  
Nisar Ali ◽  
Mohammed Benali Kanoun ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Functional Theory ◽  
P Adsorption ◽  
First Principles Study ◽  
The Density Functional Theory ◽  
Dissociation Mechanisms ◽  
Adsorption And Dissociation

Adsorption and dissociation mechanisms of H2S on a TiO2(001) surface were elucidated using first principles calculation based on the density functional theory.

scholarly journals First Principles Study on Structural and Electronic Properties of Cubic (Pm3m) And Tetragonal (P4mm) ATiO3 (A=Pb, Sn)

2020 ◽  
Vol 17 (2) ◽  
pp. 149
Author(s):  
Nurakma Natasya Md Jahangir Alam ◽  
Nur Aisyah Ab Malik Marwan ◽  
Mohd Hazrie Samat ◽  
Muhammad Zamir Mohyedin ◽  
Nur Hafiz Hussin ◽  
...  
Keyword(s):  
Cross Section ◽  
First Principles ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Ferroelectric Materials ◽  
Lead Free ◽  
Electronic Band ◽  
Functional Theory ◽  
First Principles Study ◽  
Structural And Electronic Properties

Works are centered on exploring lead-free ferroelectric materials that have a comparable unique ns2 solitary pair electrons with Pb (II), for example, Sn (II) using the first-principles study. All counts were performed dependent on Density Functional Theory (DFT) that has been executed in CASTEP. GGA-PBE displays the most exact qualities for cross-section parameters concerning exploratory qualities for both cubic PbTiO3. In the interim, GGA-PBEsol functional is exact for tetragonal PTO. The electronic band structure and density of states show the presence of hybridizations between anion O 2p and cation Pb 6s/Sn 5s unique solitary pair in tetragonal PTO and SnTO stage.

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