Atomic Scale Characterization of Oxygen Vacancy Segregation at SrTiO3 Grain Boundaries

2000 ◽  
Vol 654 ◽  
Author(s):  
R.F. Klie ◽  
N. D. Browning
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Oxygen Vacancies ◽  
Elevated Temperatures ◽  
Theoretical Models ◽  
Atomic Scale ◽  
Close Proximity ◽  
Scale Characterization

AbstractWe have examined the structure, composition and bonding at an un-doped 58° [001] tilt grain-boundary in SrTiO3 in order to investigate the control that the grain boundary exerts over the bulk properties. Room temperature and in-situ heating experiments show that there is a segregation of oxygen vacancies to the grain boundary that is increased at elevated temperatures and is independent of the cation arrangement. These measurements indicate that the widely observed electronic properties of grain boundaries may be due to an excess of mobile oxygen vacancies that cause a highly doped n-type region in the close proximity ( ≍ 1 unit cell) to the boundary. These results are shown to be consistent with both theoretical models and lower resolution chemical analysis.

Atomic-scale characterization of theSrTiO3Σ3(112)[1¯10]grain boundary

2010 ◽  
Vol 81 (13) ◽  
Author(s):  
K. J. Dudeck ◽  
N. A. Benedek ◽  
M. W. Finnis ◽  
D. J. H. Cockayne
Keyword(s):  
Grain Boundary ◽  
Atomic Scale ◽  
Scale Characterization

Atomic scale characterization of organometallic vapor phase epitaxial growth using in-situ grazing incidence X-ray scattering

1992 ◽  
Vol 124 (1-4) ◽  
pp. 1-9 ◽  
Author(s):  
D.W. Kisker ◽  
G.B. Stephenson ◽  
P.H. Fuoss ◽  
F.J. Lamelas ◽  
S. Brennan ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Vapor Phase ◽  
Grazing Incidence ◽  
Atomic Scale ◽  
X Ray ◽  
X Ray Scattering ◽  
Scale Characterization ◽  
Ray Scattering

Atomic Scale Characterization of Oxygen-Deficient Ceramic Membranes by EELS and Z-Contrast Imaging

2000 ◽  
Vol 6 (S2) ◽  
pp. 118-119
Author(s):  
Robert F. Klie ◽  
Yasuo Ito ◽  
Nigel D. Browning ◽  
Susanne Stemmer ◽  
Terry J. Mazanec
Keyword(s):  
Oxygen Vacancies ◽  
Elevated Temperatures ◽  
Equilibrium Concentration ◽  
Ceramic Membranes ◽  
Atomic Scale ◽  
Contrast Imaging ◽  
Specific Order ◽  
Scale Characterization ◽  
Temperature Equilibrium ◽  
Z Contrast

The Perovskite structured ceramic (Lax,Sr1-x)(Fey,Cr1-y)O3-δ being developed for applications in oxygen transporting membranes. The permeability of this material is limited by the number of free ions, point-defects (oxygen vacancies) and electrons in the bulk. As any ordering of these unbound particles will restrict their mobility one key issue for controlling the membrane efficiency is the formation of ordered oxygen vacancies. In particular it is very likely, that at elevated temperatures ordered micro-domains progressively grow and asymptotically reach a stable equilibrium concentration. This is consistent with the observations of Kruidhof that below a specific order-disorder transition temperature equilibrium times of 30-40 h are required to attain steady-state conditions, irrespective of the thermal history of the sample.We investigate the formation of ordered vacancies in (Lax,Sr1-x)(Fey,Cr1-y)O3-δ by atomic resolution Z-contrast imaging and electron energy-loss spectroscopy (EELS) using a 200 keV STEM/TEM JEOL2010L with a post column Gatan Image Filter (GIF).

Characterization of grain boundary phases in Si3N4 sintered using Y-Si-Al-O-N additives

1990 ◽  
Vol 48 (4) ◽  
pp. 1070-1071
Author(s):  
C. Koehler ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Elevated Temperatures ◽  
Secondary Phases ◽  
Amorphous Phases ◽  
High Temperature Mechanical Properties

The usefulness of silicon nitride as a high temperature ceramic can be limited by the presence of amorphous phases at the grain boundaries. Dense silicon nitride ceramics are produced using pressureless sintering of Si3N4 with Y-Si-Al-O-N additives. When these additives are left as a glassy phase at the grain boundaries and triple grain junctions, the mechanical properties at elevated temperatures are weakened due to these low viscous glasses. Post-sintering heat treatments and close compositional control can be effective in transforming the glass into crystalline phases at the grain boundaries thereby increasing the refractoriness.To optimize high temperature mechanical properties, processing must be controlled not only to fully crystallize the grain boundaries but also to avoid certain unstable secondary phases whose oxidation leads to large molar volume changes which causes possible cracking. Transmisssion electron microscopy and x-ray microanalysis (EDS) are significant methods to characterize the amorphous grain boundary pockets and to identify the crystalline grain boundary phases.

An atomic scale characterization of coupled grain boundary motion in silicon bicrystals

2015 ◽  
Vol 95 (36) ◽  
pp. 4118-4129 ◽  
Author(s):  
Stefan Bringuier ◽  
Venkateswara Rao Manga ◽  
Keith Runge ◽  
Pierre Deymier ◽  
Krishna Muralidharan
Keyword(s):  
Grain Boundary ◽  
Atomic Scale ◽  
Boundary Motion ◽  
Scale Characterization ◽  
Grain Boundary Motion
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