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Atomic scale verification of oxide-ion vacancy distribution near a single grain boundary in YSZ.

An J, Park JS, Koh AL, Lee HB, Jung HJ, Schoonman J, Sinclair R, Gür TM, Prinz FB - Sci Rep (2013)

Bottom Line: We show significant oxygen deficiency due to segregation of oxide-ion vacancies near the grain-boundary core with half-width < 0.6 nm.Oxide-ion density distribution near a grain boundary simulated by molecular dynamics corroborated well with experimental results.Such column-by-column quantification of defect concentration in functional materials can provide new insights that may lead to engineered grain boundaries designed for specific functionalities.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA [2].

ABSTRACT
This study presents atomic scale characterization of grain boundary defect structure in a functional oxide with implications for a wide range of electrochemical and electronic behavior. Indeed, grain boundary engineering can alter transport and kinetic properties by several orders of magnitude. Here we report experimental observation and determination of oxide-ion vacancy concentration near the Σ13 (510)/[001] symmetric tilt grain-boundary of YSZ bicrystal using aberration-corrected TEM operated under negative spherical aberration coefficient imaging condition. We show significant oxygen deficiency due to segregation of oxide-ion vacancies near the grain-boundary core with half-width < 0.6 nm. Electron energy loss spectroscopy measurements with scanning TEM indicated increased oxide-ion vacancy concentration at the grain boundary core. Oxide-ion density distribution near a grain boundary simulated by molecular dynamics corroborated well with experimental results. Such column-by-column quantification of defect concentration in functional materials can provide new insights that may lead to engineered grain boundaries designed for specific functionalities.

No MeSH data available.


Related in: MedlinePlus

Hybrid MC-MD simulation results for, (a) a simulation cell with two Σ13(510)/[001] GBs, (b) 2-D distribution of cations, and (c) 2-D distribution of oxide-ions.
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f3: Hybrid MC-MD simulation results for, (a) a simulation cell with two Σ13(510)/[001] GBs, (b) 2-D distribution of cations, and (c) 2-D distribution of oxide-ions.

Mentions: To gain more insight into TEM observations near the grain boundary, atomistic simulation was performed using a hybrid Monte Carlo (MC) - Molecular Dynamics (MD) algorithm with periodic boundary conditions. Figure 3(a) shows an example of the simulation cell, which is in size and has two Σ13(510)/[001] GBs (one at + 3 nm and the other at –3 nm in the x-coordinate), where α is the lattice constant and θ is a half of the tilt angle (11.3°). Figure 3(b) and 3(c) show the cation and oxide-ion density distributions obtained from the hybrid MC-MD simulation. Individual atomic columns can easily be identified, and the decrease of both cation and oxide-ion densities near the GBs is confirmed. This is in good agreement with the experimental results and reflects reduced atomic packing in the vicinity of the GBs. Also the change in the ion density distribution along the GB (vertical direction in the figures) is more pronounced than within the cells (or, grains) away from the GB region, which explains why the error bar size at the GB corresponding to the variation in composition from one position to another is significantly larger than that in the non-GB region in Figure 2(b).


Atomic scale verification of oxide-ion vacancy distribution near a single grain boundary in YSZ.

An J, Park JS, Koh AL, Lee HB, Jung HJ, Schoonman J, Sinclair R, Gür TM, Prinz FB - Sci Rep (2013)

Hybrid MC-MD simulation results for, (a) a simulation cell with two Σ13(510)/[001] GBs, (b) 2-D distribution of cations, and (c) 2-D distribution of oxide-ions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3775093&req=5

f3: Hybrid MC-MD simulation results for, (a) a simulation cell with two Σ13(510)/[001] GBs, (b) 2-D distribution of cations, and (c) 2-D distribution of oxide-ions.
Mentions: To gain more insight into TEM observations near the grain boundary, atomistic simulation was performed using a hybrid Monte Carlo (MC) - Molecular Dynamics (MD) algorithm with periodic boundary conditions. Figure 3(a) shows an example of the simulation cell, which is in size and has two Σ13(510)/[001] GBs (one at + 3 nm and the other at –3 nm in the x-coordinate), where α is the lattice constant and θ is a half of the tilt angle (11.3°). Figure 3(b) and 3(c) show the cation and oxide-ion density distributions obtained from the hybrid MC-MD simulation. Individual atomic columns can easily be identified, and the decrease of both cation and oxide-ion densities near the GBs is confirmed. This is in good agreement with the experimental results and reflects reduced atomic packing in the vicinity of the GBs. Also the change in the ion density distribution along the GB (vertical direction in the figures) is more pronounced than within the cells (or, grains) away from the GB region, which explains why the error bar size at the GB corresponding to the variation in composition from one position to another is significantly larger than that in the non-GB region in Figure 2(b).

Bottom Line: We show significant oxygen deficiency due to segregation of oxide-ion vacancies near the grain-boundary core with half-width < 0.6 nm.Oxide-ion density distribution near a grain boundary simulated by molecular dynamics corroborated well with experimental results.Such column-by-column quantification of defect concentration in functional materials can provide new insights that may lead to engineered grain boundaries designed for specific functionalities.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA [2].

ABSTRACT
This study presents atomic scale characterization of grain boundary defect structure in a functional oxide with implications for a wide range of electrochemical and electronic behavior. Indeed, grain boundary engineering can alter transport and kinetic properties by several orders of magnitude. Here we report experimental observation and determination of oxide-ion vacancy concentration near the Σ13 (510)/[001] symmetric tilt grain-boundary of YSZ bicrystal using aberration-corrected TEM operated under negative spherical aberration coefficient imaging condition. We show significant oxygen deficiency due to segregation of oxide-ion vacancies near the grain-boundary core with half-width < 0.6 nm. Electron energy loss spectroscopy measurements with scanning TEM indicated increased oxide-ion vacancy concentration at the grain boundary core. Oxide-ion density distribution near a grain boundary simulated by molecular dynamics corroborated well with experimental results. Such column-by-column quantification of defect concentration in functional materials can provide new insights that may lead to engineered grain boundaries designed for specific functionalities.

No MeSH data available.


Related in: MedlinePlus