Chromium point defects in hexagonalBaTiO3: A comparative study of first-principles calculations and experiments

2015 ◽  
Vol 91 (15) ◽  
Author(s):  
Sanjeev K. Nayak ◽  
Hans T. Langhammer ◽  
Waheed A. Adeagbo ◽  
Wolfram Hergert ◽  
Thomas Müller ◽  
...  
Keyword(s):  
Comparative Study ◽  
Point Defects ◽  
First Principles ◽  
First Principles Calculations

scholarly journals First Principles Calculations of Defects in Unstable Crystals: Austenitic Iron

2011 ◽  
Vol 1363 ◽  
Author(s):  
G.J. Ackland ◽  
T.P.C. Klaver ◽  
D.J. Hepburn
Keyword(s):  
Point Defects ◽  
First Principles ◽  
Defect Formation ◽  
Single Layer ◽  
Temperature Limit ◽  
Reference State ◽  
First Principles Calculations ◽  
General Picture ◽  
Bcc Iron ◽  
Defect Energies

ABSTRACTFirst principles calculations have given a new insight into the energies of point defects in many different materials, information which cannot be readily obtained from experiment. Most such calculations are done at zero Kelvin, with the assumption that finite temperature effects on defect energies and barriers are small. In some materials, however, the stable crystal structure of interest is mechanically unstable at 0K. In such cases, alternate approaches are needed. Here we present results of first principles calculations of austenitic iron using the VASP code. We determine an appropriate reference state for collinear magnetism to be the antiferromagnetic (001) double-layer (AFM-d) which is both stable and lower in energy than other possible models for the low temperature limit of paramagnetic fcc iron. Another plausible reference state is the antiferromagnetic (001) single layer (AFM-1). We then consider the energetics of dissolving typical alloying impurities (Ni, Cr) in the materials, and their interaction with point defects typical of the irradiated environment. We show that the calculated defect formation energies have fairly high dependence on the reference state chosen: in some cases this is due to instability of the reference state, a problem which does not seem to apply to AFM-d and AFM-1. Furthermore, there is a correlation between local free volume magnetism and energetics. Despite this, a general picture emerge that point defects in austenitic iron have geometries similar to those in simpler, non-magnetic, thermodynamically stable FCC metals. The defect energies are similar to those in BCC iron. The effect of substitutional Ni and Cr on defect properties is weak, rarely more than tenths of eV, so it is unlikely that small amounts of Ni and Cr will have a significant effect on the radiation damage in austenitic iron at high temperatures.

scholarly journals A comparative study on the functionality of S- and P-based lubricant additives by combined first principles and experimental analysis

RSC Advances ◽  
2016 ◽  
Vol 6 (53) ◽  
pp. 47753-47760 ◽  
Author(s):  
M. C. Righi ◽  
S. Loehlé ◽  
M. I. De Barros Bouchet ◽  
S. Mambingo-Doumbe ◽  
J. M. Martin
Keyword(s):  
Shear Strength ◽  
Comparative Study ◽  
Surface Chemistry ◽  
Tribological Properties ◽  
Experimental Analysis ◽  
First Principles ◽  
Lubricant Additives ◽  
First Principles Calculations

Sulfur reduces the adhesion and shear strength of iron more effectively than phosphorus. The surface chemistry, well described by first principles calculations, impacts macroscale tribological properties.

scholarly journals Effect of point defects on the electronic density states of SnC nanosheets: First-principles calculations

2017 ◽  
Vol 7 ◽  
pp. 3209-3215 ◽  
Author(s):  
Soleyman Majidi ◽  
Amine Achour ◽  
D.P. Rai ◽  
Payman Nayebi ◽  
Shahram Solaymani ◽  
...  
Keyword(s):  
Point Defects ◽  
First Principles ◽  
First Principles Calculations ◽  
Electronic Density

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.

scholarly journals Native point defects in CuIn1−xGaxSe2: hybrid density functional calculations predict the origin of p- and n-type conductivity

2014 ◽  
Vol 16 (40) ◽  
pp. 22299-22308 ◽  
Author(s):  
J. Bekaert ◽  
R. Saniz ◽  
B. Partoens ◽  
D. Lamoen
Keyword(s):  
Charge Carrier ◽  
Point Defects ◽  
First Principles ◽  
Density Functional Calculations ◽  
Density Functional ◽  
First Principles Calculations ◽  
Photoluminescence Spectra ◽  
Type Conductivity ◽  
Native Point Defects ◽  
Hybrid Density Functional

Starting from first-principles calculations, many experimental observations such as photoluminescence spectra, charge carrier densities and freeze-out can be explained.

Adsorption of Methane on Pristine and Al-Doped Graphene: A Comparative Study via First-Principles Calculation

2012 ◽  
Vol 602-604 ◽  
pp. 870-873 ◽  
Author(s):  
Wei Zhao ◽  
Qing Yuan Meng
Keyword(s):  
Charge Transfer ◽  
Binding Energy ◽  
Comparative Study ◽  
First Principles ◽  
First Principles Calculation ◽  
Pristine Graphene ◽  
First Principles Calculations ◽  
Graphene Surface ◽  
Doped Graphene ◽  
Adsorption Of Methane

The adsorption of methane (CH4) molecule on the pristine and Al-doped (4, 8) graphene was investigated via the first-principles calculations. The results demonstrated that, in comparison to the adsorption of a CH4molecule on the pristine graphene sheet, a relatively stronger adsorption was observed between the CH4molecule and Al-doped graphene with a shorter adsorption distance, larger binding energy and more charge-transfer from the graphene surface to the CH4molecule. Therefore, the Al-doped graphene can be expected to be a novel sensor for the detection of CH4molecules in future applications.

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