scholarly journals Calculation of Defect Properties of NiTi and FeTi

1990 ◽  
Vol 209 ◽  
Author(s):  
Russell T. Lutton ◽  
Michael J. Sabochick ◽  
Nghi Q. Lam
Keyword(s):  
Atomistic Simulation ◽  
Antisite Defect ◽  
Vacancy Formation ◽  
Stable Configuration ◽  
Antisite Defects ◽  
Formation Energies

ABSTRACTThe energies and configurations of interstitials and vacancies in the B2 ordered compounds NiTi and FeTi were calculated using atomistic simulation. The stable configuration of a vacancy after the removal of an Ni atom was a vacant Ni site; similarly, the removal of an Fe atom in FeTi resulted in a vacant Fe site. Removal of a Ti atom in both compounds, however, resulted in a vacant Ni or Fe site and an adjacent antisite defect. The effective vacancy formation energies in NiTi and FeTi were calculated to be 1.48 and 1.07 eV, respectively. Interstitials in NiTi formed split <111> configurations consisting of a Ni-Ni dumbbell oriented in the <111> direction with one or two adjacent antisite defects. The Fe interstitial in FeTi had a similar configuration, except the dumbbell contained Fe atoms. The Ti interstitial in FeTi formed an <110> Fe-Fe dumbbell.

Point defect study of CuTi and CuTi2

1991 ◽  
Vol 6 (3) ◽  
pp. 473-482 ◽  
Author(s):  
J.R. Shoemaker ◽  
R.T. Lutton ◽  
D. Wesley ◽  
W.R. Wharton ◽  
M.L. Oehrli ◽  
...  
Keyword(s):  
Atomistic Simulation ◽  
Formation Energy ◽  
Antisite Defect ◽  
Two Dimensional ◽  
Migration Energy ◽  
Vacancy Migration ◽  
Embedded Atom ◽  
Antisite Defects ◽  
Formation Energies ◽  
Vacancy Migration Energy

The energies and configurations of interstitials and vacancies in the ordered compounds CuTi and CuTi2 were determined using atomistic simulation with realistic embedded-atom potentials. The formation energy of an antisite pair was found to be 0.385 and 0.460 eV in CuTi and CuTi2, respectively. In both compounds, the creation of a vacancy by the removal of either a Cu or Ti atom resulted in a vacant Cu site, with an adjacent antisite defect in the case of the Ti vacancy. The vacant Cu site in CuTi was found to be very mobile within two adjacent (001) Cu planes, with a migration energy of 0.19 eV, giving rise to two-dimensional migration. The vacancy migration energy across (001) Ti planes, however, was 1.32 eV, which could be lowered to 0.75 or 0.60 eV if one or two Cu antisite defects were initially present in these planes. In CuTi2, the vacancy migration energy of 0.92 eV along the (001) Cu plane was significantly higher than in CuTi. The effective vacancy formation energies were calculated to be 1.09 eV and 0.90 eV in CuTi and CuTi2, respectively. Interstitials created by inserting either a Cu or Ti atom had complicated configurations in which a Cu 〈111〉 split interstitial was surrounded by two or three Ti antisite defects. The interstitial formation energy was estimated to be 1.7 eV in CuTi and 1.9 eV in CuTi2.

scholarly journals Energetics and Configurations of Lattice Defects in CuTi

1990 ◽  
Vol 193 ◽  
Author(s):  
James R. Shoemaker ◽  
David Wesley ◽  
William R. Wharton ◽  
Michael L. Oehrli ◽  
Michael J. Sabochick ◽  
...  
Keyword(s):  
Atomistic Simulation ◽  
Antisite Defect ◽  
Lattice Defects ◽  
Two Dimensional ◽  
Antisite Defects

ABSTRACTThe energies and configurations of interstitials and vacancies in the ordered compound CuTi were calculated using atomistic simulation. Vacancies created by the removal of either a Cu or Ti atom resulted in a vacant Cu site, with an antisite defect in the latter case. The vacancy at the Cu site was found to be very mobile within two adjacent (001) Cu planes, resulting in two dimensional migration. Interstitials created by inserting either a Cu or Ti atom had complicated configurations containing one or more antisite defects.

Defect Properties in GaN: Ab Initio and Empirical Potential Calculations

2005 ◽  
Vol 475-479 ◽  
pp. 3087-3090 ◽  
Author(s):  
Fei Gao ◽  
Eric J. Bylaska ◽  
William J. Weber
Keyword(s):  
Dft Calculations ◽  
Density Functional ◽  
Reasonable Agreement ◽  
Stable Configuration ◽  
Functional Theory ◽  
Empirical Potential ◽  
Antisite Defects ◽  
Formation Energies ◽  
Dynamics Method ◽  
Weber Potential

The defect properties and atomic configurations in GaN have been comparatively investigated using density functional theory (DFT) and molecular dynamics method with two representative potentials. The DFT calculations show that the relaxation of vacancies is generally small, but the relaxation around antisite defects is large. The N interstitials, starting from any possible configurations, eventually relax into a N+-N< 0 2 11 > split interstitial. In the case of Ga interstitials, the most stable configuration is a Ga octahedral interstitial, but the Ga+-Ga< 0 2 11 > split interstitial can bridge the gap between non-bounded Ga atoms. The formation energies of vacancies and antisite defects obtained using the Stillinger-Weber potential (SW) are in reasonable agreement with those obtained by DFT calculations, whereas the Tersoff-Brenner (TB) potential better describes the behavior of N interstitials.

scholarly journals Oxygen vacancy formation energies in PbTiO3/SrTiO3 superlattice

2018 ◽  
Vol 2 (6) ◽  
Author(s):  
Lipeng Zhang ◽  
Isaac Bredeson ◽  
Axiel Y. Birenbaum ◽  
P. R. C. Kent ◽  
Valentino R. Cooper ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Vacancy Formation ◽  
Oxygen Vacancy Formation ◽  
Formation Energies

EL2 and gallium antisite defects in GaAs: Si

1989 ◽  
Vol 67 (4) ◽  
pp. 375-378 ◽  
Author(s):  
C. K. Teh ◽  
F. L. Weichman ◽  
C. C. Tin ◽  
P. A. Barnes
Keyword(s):  
Fourier Transform ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Fourier Transform Infrared ◽  
Antisite Defect ◽  
Longitudinal Optic ◽  
Related Defect ◽  
Antisite Defects ◽  
Transient Spectroscopy ◽  
Silicon Doped

Photoluminescence (PL), Fourier-transform infrared (FTIR), and deep-level transient spectroscopy (DLTS) measurements have been made on various samples of silicon-doped liquid-encapsulated Czochralski-grown GaAs. All the samples show prominent PL peaks at 1.443 and 1.325 eV together with their longitudinal optic (LO) phonon peaks. The PL peak at 1.443 eV has been reported in the literature as being due to either GaAs or a boron-related defect. The FTIR results show the presence of BGa at 540.3 and 517.0 cm−1 and SiGa at 383.6 cm−1. We have observed that there is no correlation between the PL peak at 1.443 eV and BGa. Thus, we believe that this PL peak is related to the GaAs antisite defect. The presence of EL2 in the samples has been measured using DLTS. We have found that the intensity of the PL peak at 1.443 eV varies inversely with that of the EL2 peak. This relationship indirectly confirms that the 1.443 eV peak is due to the gallium antisite defect. The PL peak at 1.325 eV is significantly different from those reported in the literature for GaAs:Si. Measurements have also been made on samples of GaAs:Si annealed under different arsenic overpressures.

STRUCTURAL AND ELECTRONIC PROPERTIES OF c-BN(110) SURFACE AND SURFACE POINT DEFECTS

2006 ◽  
Vol 17 (06) ◽  
pp. 795-803 ◽  
Author(s):  
HATICE KÖKTEN ◽  
ŞAKIR ERKOÇ
Keyword(s):  
Point Defects ◽  
Cubic Boron Nitride ◽  
Vacancy Formation ◽  
Surface Point ◽  
Hartree Fock ◽  
Structural And Electronic Properties ◽  
Structure Surface ◽  
Surface Vacancy ◽  
First Time ◽  
Formation Energies

The surface structure, surface energy, and surface vacancy formation energy for B and N vacancy of the cubic boron nitride (c-BN)(110) surface have been investigated by performing Hartree-Fock and DFT calculations. Results are compared with available literature values. The vacancy formation energies [unrelaxed [Formula: see text] and relaxed (Ef)] are reported for the first time for c-BN(110).

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