Piezoelectricity in the {AxA`(1-x)}BO3 and A{BxB`(1-x)}O3 Ceramic Alloys

2018 ◽  
Vol 915 ◽  
pp. 34-38
Author(s):  
Berna Akgenc ◽  
Çetin Tasseven ◽  
Tahir Çağın
Keyword(s):  
Density Functional ◽  
Chemical Nature ◽  
Piezoelectric Properties ◽  
Divalent Metal ◽  
Size Difference ◽  
First Principle ◽  
Functional Theory ◽  
Ceramic Oxides ◽  
First Principle Calculations ◽  
Bulk Ceramic

ABO3 perovskite ceramics due to their chemical nature and size difference of the cations A (where A is a divalent metal) and B (where B is a tetravalent metal) have non-centro-symmetric polymorphs and display significant piezoelectric properties. One path to improve piezoelectric properties is through alloying these materials. In order to assess the feasibility of this, we have investigated the structure, elastic and piezoelectric properties of prototypical cubic and tetragonal phases of ABO3 bulk ceramic oxides and their alloys: {AxA`(1-x)}BO3 and A{BxB`(1-x)}O3 by density functional theory based first-principle calculations. Using 2x2x2 super cells as models in our calculations, we have covered the full alloying range by varying concentration, x, in steps of 12.5%. We have created models using Ba, Sr, Pb, for A and A`, and Ti, Zr for B and B` both in cubic and tetragonal super cells. Here, we will report the structural and piezoelectric properties of tetragonal phases of ABO3 bulk ceramic oxides and their alloys.

Electronic Structures of Vacancy Defective Chiral (6,2) SiC Nanotubes

2017 ◽  
Vol 896 ◽  
pp. 3-8
Author(s):  
Ke Jian Li ◽  
Hong Xia Liu
Keyword(s):  
Density Functional Theory ◽  
Silicon Carbide ◽  
Electronic Structures ◽  
Density Functional ◽  
First Principle ◽  
Defect Level ◽  
Functional Theory ◽  
Vacancy Defects ◽  
First Principle Calculations ◽  
Silicon Carbide Nanotubes

Vacancy defects are common defects formed in the syntheses of silicon carbide nanotubes (SiCNTs) and seriously impact the electronic structures of the nanotubes. With first-principle calculations based on density functional theory (DFT), vacancy defective (6,2) SiCNTs are studied. Vacancies form a pair of fivefold and ninefold rings. Carbon vacancy introduces an occupied defect level near the top of the valence band and an unoccupied level in the conduction band. Three defect levels are found in the band gap of the SiCNT with a silicon vacancy. These results are helpful for investigations on SiCNT devices and sensors.

Theoretical Analysis of the DOS and Band Structural Properties of Ti1-XSnxO2 Solid Solutions

2012 ◽  
Vol 465 ◽  
pp. 33-36
Author(s):  
Zhi Dong Lin ◽  
Wen Long Song ◽  
Ju Cheng Zheng
Keyword(s):  
Band Gap ◽  
Solid Solutions ◽  
Density Functional ◽  
Wide Band ◽  
Low Energy ◽  
Low Density ◽  
First Principle ◽  
Wide Band Gap ◽  
Functional Theory ◽  
First Principle Calculations

The band structure and density of states (DOS) of Ti1-xSnxO2 solid solutions with x=0, 1/8, 1/4, 1/2 and 1 were investigated by means of the first-principle calculations based on density functional theory. The result indicated that band gap and Fermi level of TiO2-SnO2 vary continuously from those of pure TiO2 to those of Sn content increasing. In addition, the DOS moves towards low energy and the bang gap is broadened with growing value of x. The wide band gap and the low density of the states in the conduction band result in the enhancement of photoactivity in Ti1-xSnxO2.

scholarly journals Elastic and optical properties of sillenites: First principle calculations

2020 ◽  
Vol 557 (1) ◽  
pp. 98-104 ◽  
Author(s):  
Husnu Koc ◽  
Selami Palaz ◽  
Sevket Simsek ◽  
Amirullah M. Mamedov ◽  
Ekmel Ozbay
Keyword(s):  
Optical Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Electronic Band Structure ◽  
First Principle ◽  
Electronic Band ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Optical Functions ◽  
The Density Functional Theory

In the present paper, we have investigated the electronic structure of some sillenites - Bi12MO20 (M = Ti, Ge, and Si) compounds based on the density functional theory. The mechanical and optical properties of Bi12MO20 have also been computed. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work. The band gap trend in Bi12MO20 can be understood from the nature of their electronic structures. The obtained electronic band structure for all Bi12MO20 compounds is semiconductor in nature. Similar to other oxides, there is a pronounced hybridization of electronic states between M-site cations and anions in Bi12MO20. Based on the obtained electronic structures, we further calculate the frequency-dependent dielectric function and other optical functions.

scholarly journals Structural and Electronic Properties of Pure Ta, TaNO, and TaZrNO with Ab Initio Calculations

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
T. Chihi ◽  
M. Fatmi ◽  
M. Guemmaz ◽  
J. C. Parlebas
Keyword(s):  
Interatomic Distance ◽  
Density Functional ◽  
Electronic Conductivity ◽  
First Principle ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Structural And Electronic Properties ◽  
Densities Of States ◽  
Self Consistent ◽  
The Difference

This paper presents the results of self-consistent first-principle calculations for the crystal structure and electronic structure of pure tantalum, TaNO, and TaZrNO within density functional theory (DFT) for the sake of comparison and shows the influence of allowing elements on the interatomic distance and the Fermi level. The large total densities of states (TDOS) value for TaZrNO implies the highest electronic conductivity. The difference in values is due to the Zr metallic atoms presence in TaZrNO compound. There is a strong interaction between Ta and (N, O) (Ta−N=0.39, Ta−O=0.21) in TaON compound, and Zr presence increases this interaction (Ta−N=1.74, Ta−O=0.30) in TaZrON compound.

scholarly journals First Principle Calculations for Silver Halides AgBr, AgCl, and AgF

2021 ◽  
Vol 9 (2) ◽  
pp. 71-75
Author(s):  
Akram H. Taha
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Total Density ◽  
First Principle ◽  
Silver Halides ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Almost All ◽  
Total Density Of States ◽  
Good Agreement

Density functional theory (DFT) coupled with ) method are carried out to calculate the electronic structures of AgX (X; Br, Cl, and F). The effect of hybridizing between 4d orbital of Ag element and the p orbitals of the X in the valence band plays a very important role in the total density of states configuration. The electronic structure has been studied and all results were compared with the experimental and theoretical values. The importance of this work is that there is insufficient studies of silver halides corresponding the great importance of these compounds. Almost all the results were consistent with the previous studies mentioned here. We found the band gap of AgX to be 2.343 eV, 2.553 eV, and 1.677 eV for AgBr, AgCl, and AgF respectively which are in good agreement with the experimental results.      

First-Principle Investigation of Lithium Intercalation Behavior of a (3, 3) Carbon Nanotube

2012 ◽  
Vol 736 ◽  
pp. 27-31
Author(s):  
Kulpreet Singh Virdi ◽  
K.C. Hari Kumar
Keyword(s):  
Density Functional Theory ◽  
Carbon Nanotube ◽  
Density Functional ◽  
Lithium Atom ◽  
Energy Difference ◽  
Lithium Intercalation ◽  
First Principle ◽  
Tube Axis ◽  
Functional Theory ◽  
First Principle Calculations

Using first-principle calculations employing density functional theory (DFT) the stabilityof a (3, 3) carbon nanotube (CNT) intercalated with lithium atoms, with respect to their position aswell as Li/C ratio, is studied. On varying the distance of a lithium atom from the axis of the CNT in theradial direction, through the center of a graphitic hexagon, minimum of energy of the system occursat a distance of 3.8 °A from the axis. Keeping the distance of the lithium atom from the tube axis fixedat 3.8 °A, intercalation energy (E) was calculated while the number of lithium atoms is varied fromone (Li1C12, −0.511 eV) to six (Li6C12, −0.615 eV). It is found that the intercalation becomes morefavorable with the increase in number of lithium atoms intercalated and increase in the symmetryof the intercalated system. The maximum intercalation energy difference between successive lithiumatom additions lay within 0.1 eV.

scholarly journals Strain-induced band modulation and excellent stability, transport and optical properties of penta-MP2 (M = Ni, Pd, and Pt) monolayers

2020 ◽  
Vol 2 (10) ◽  
pp. 4566-4580 ◽  
Author(s):  
Vipin Kumar ◽  
Debesh R. Roy
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Electronic Properties ◽  
Density Functional ◽  
First Principle ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Biaxial Tensile ◽  
Tensile Strains ◽  
Excellent Stability

First principle calculations utilizing density functional theory were carried out to investigate electronic properties, transport and optical properties of penta-MP2 (M = Ni, Pd and Pt) monolayer compounds under applied uniaxial and biaxial tensile strains.

scholarly journals In-depth first-principle study on novel MoS2 polymorphs

RSC Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 3759-3769
Author(s):  
Håkon Eidsvåg ◽  
Murugesan Rasukkannu ◽  
Dhayalan Velauthapillai ◽  
Ponniah Vajeeston
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
First Principle ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Photovoltaic Applications

14 new MoS2 polymorphs were studied using first-principle calculations based on density functional theory. We found a new promising MoS2 candidate for photocatalytic and photovoltaic applications.

First-principle calculations of the structure and elastic properties of GaAs under pressure

2009 ◽  
Vol 87 (2) ◽  
pp. 153-159 ◽  
Author(s):  
Hong-Ling Cui ◽  
Fen Luo ◽  
Xiang-Rong Chen ◽  
Guang-Fu Ji
Keyword(s):  
First Principles ◽  
Density Functional ◽  
First Principle ◽  
Pressure Derivative ◽  
Functional Theory ◽  
Plane Wave Method ◽  
First Principle Calculations ◽  
Zinc Blende ◽  
Debye Temperatures ◽  
Theoretical Results

A first-principles plane-wave method with the ultrasoft pseudopotential scheme in the framework of density functional theory is performed to calculate the lattice parameters, the bulk modulus B0 and its pressure derivative B0' of the zinc-blende GaAs (ZB–GaAs), rocksalt GaAs (RS–GaAs), CsCl–GaAs, NiAs–GaAs, and wurtzite GaAs (WZ–GaAs). We also calculate the phase transition pressures between different phases, Debye temperatures, and the anisotropies. Our results are consistent with other theoretical results.

Density functional theory study of Li binding to graphene

RSC Advances ◽  
2016 ◽  
Vol 6 (32) ◽  
pp. 26540-26545 ◽  
Author(s):  
Guangmin Yang ◽  
Xiaofeng Fan ◽  
Zhicong Liang ◽  
Qiang Xu ◽  
Weitao Zheng
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
First Principle ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Li Adsorption

Using first-principle calculations, we studied the interaction between Li and graphene by considering the two kinds of models, which are related to the configurations of Li adsorption and the concentration of Li on graphene.

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