Simultaneous Study of Vacancy Formation and Migration at High Temperatures inB2-Type Fe Aluminides

1995 ◽  
Vol 75 (1) ◽  
pp. 97-100 ◽  
Author(s):  
R. Würschum ◽  
C. Grupp ◽  
H.-E. Schaefer
Keyword(s):  
High Temperatures ◽  
Vacancy Formation ◽  
Simultaneous Study ◽  
And Migration

Atomic Defects in Intermetallic Compounds and Diffusion Processes

1998 ◽  
Vol 527 ◽  
Author(s):  
H.-E. Schaefer ◽  
K. Frenner ◽  
R. Würschum
Keyword(s):  
Transition Metal ◽  
Intermetallic Compounds ◽  
High Temperatures ◽  
Diffusion Processes ◽  
Formation Enthalpy ◽  
Length Change ◽  
Vacancy Formation ◽  
And Migration ◽  
Lifetime Studies ◽  
Metal Aluminides

ABSTRACTFor the understanding of the properties of the technically important intermetallic compounds as transition metal aluminides and silicides the understanding of atomic defect properties is pivotal. From recent positron lifetime studies high or low values for the effective vacancy formation enthalpy were found for close-packed or for more open-structured bcc type compounds, respectively, which can be well understood theoretically. In B2-FeAl the vacancy migration enthalpy could be additionally derived at high temperatures from vacancy equilibration processes. It is shown here by a study on B2-FeAl in comparison to the positron annihilation experiments that the thermal formation and migration of defects can be specifically investigated by time-dependent length-change experiments at high temperatures by the defect equilibration behavior after temperature changes. With the present data on vacancy formation and migration the wide variation of the transition-metal self-diffusivities in intermetallic compounds can be understood.

Thermal vacancy formation and positron–vacancy interaction in Ti3Al at high temperatures

1996 ◽  
Vol 80 (2) ◽  
pp. 724-728 ◽  
Author(s):  
R. Würschum ◽  
E. A. Kümmerle ◽  
K. Badura‐Gergen ◽  
A. Seeger ◽  
Ch. Herzig ◽  
...  
Keyword(s):  
High Temperatures ◽  
Vacancy Formation ◽  
Thermal Vacancy

Thermodynamics of Oxygen Chemistry on PbTiO3 and LaMnO3 (001) Surfaces

2011 ◽  
Vol 1309 ◽  
Author(s):  
Ghanshyam Pilania ◽  
R. Ramprasad
Keyword(s):  
Phase Diagram ◽  
High Temperatures ◽  
First Principles ◽  
Room Temperature ◽  
Oxidation Catalysis ◽  
Vacancy Formation ◽  
Surface Phase ◽  
Surface Phases ◽  
O Vacancy ◽  
Low Pressures

ABSTRACTWe present a first principles thermodynamic study of O ad-atom and vacancy formation on the AO- and BO2-terminated (001) surfaces of the PbTiO3 (PTO) and LaMnO3 (LMO) cubic perovskites. Our results show that, owing to the highly energetically unfavorable nature of O vacancy formation on these surfaces, O vacancies appear only at high temperatures and practically irrelevant low pressures on the (T, p) surface phase diagram. In contrast, effortless formation of O ad-atoms on the surfaces is encountered at practically achievable pressures and temperatures. Above room temperature and close to atmospheric pressures, we predict clean PbO and TiO2-terminated (001) PTO surfaces as the stable surface phases while partially or fully O ad-atom covered surfaces are found to be more stable for LMO. These results are consistent with the observation that LMO is far more active towards oxidation catalysis than PTO.

Property of mono-vacancy in MAX phase M3AC2 (M=Ti, A=Al, Si, or Ge): First-principles calculations

2018 ◽  
Vol 32 (15) ◽  
pp. 1850160 ◽  
Author(s):  
L. Chen ◽  
G. Duan ◽  
X. F. Gao ◽  
C. L. Wang
Keyword(s):  
High Temperature ◽  
First Principles ◽  
Radiation Resistance ◽  
Atomic Layer ◽  
Experimental Results ◽  
Max Phase ◽  
Vacancy Formation ◽  
First Principles Calculations ◽  
Density Of State ◽  
And Migration

The formation and migration energies of the mono-vacancy in M3AC2 have been investigated using first-principles calculations. The results have shown that M element vacancy formation is the most energetically difficult in M3AC2. The A atomic layer is the most active one. It was also found that the energies of mono-vacancy formation and migration in Ti3AlC2 are higher than that in Ti3SiC2 and Ti3GeC2. Moreover, our calculation of the density of state confirms the conclusion that Ti3AlC2 is the most stable in the selected M3AC2 materials under high-temperature or irradiation environment conditions. These results could provide theoretical insights for the experimental results that Ti3AlC2 has a better radiation resistance than Ti3SiC2 and Ti3GeC2.

Vacancy formation and migration energies in strained crystals

1983 ◽  
Vol 114 (1) ◽  
pp. 22-29 ◽  
Author(s):  
C.C. Matthai ◽  
D.J. Bacon
Keyword(s):  
Vacancy Formation ◽  
And Migration

Oxygen vacancy formation and migration in ceria

2006 ◽  
Vol 177 (35-36) ◽  
pp. 3069-3074 ◽  
Author(s):  
M NOLAN ◽  
J FEARON ◽  
G WATSON
Keyword(s):  
Oxygen Vacancy ◽  
Vacancy Formation ◽  
Oxygen Vacancy Formation ◽  
And Migration

Oxygen vacancy formation and migration in double perovskite Sr2CrMoO6: a first-principles study

RSC Advances ◽  
2016 ◽  
Vol 6 (49) ◽  
pp. 43034-43040 ◽  
Author(s):  
Shuai Zhao ◽  
Liguo Gao ◽  
Chunfeng Lan ◽  
Shyam S. Pandey ◽  
Shuzi Hayase ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
First Principles ◽  
Double Perovskite ◽  
Vacancy Formation ◽  
First Principles Study ◽  
Oxygen Vacancy Formation ◽  
And Migration ◽  
Theoretical Insight ◽  
Insight Into

These calculations provided theoretical insight into the effect of the B-site Cr and Mo on the oxygen vacancy formation and migration in the double perovskite Sr2CrMoO6 using the DFT+U method.

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