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Atomically ordered solute segregation behaviour in an oxide grain boundary

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ABSTRACT

Grain boundary segregation is a critical issue in materials science because it determines the properties of individual grain boundaries and thus governs the macroscopic properties of materials. Recent progress in electron microscopy has greatly improved our understanding of grain boundary segregation phenomena down to atomistic dimensions, but solute segregation is still extremely challenging to experimentally identify at the atomic scale. Here, we report direct observations of atomic-scale yttrium solute segregation behaviours in an yttria-stabilized-zirconia grain boundary using atomic-resolution energy-dispersive X-ray spectroscopy analysis. We found that yttrium solute atoms preferentially segregate to specific atomic sites at the core of the grain boundary, forming a unique chemically-ordered structure across the grain boundary.

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Atomic structure of the grain boundary.(a) HAADF-STEM image of the GB. (b,c) Atomic resolution EDS elemental maps for (b) Zr K map, (c) Y K maps in the bulk region of the YSZ along [110] direction. Scale bar is 1 nm in (a) and 0.5 nm in (b,c).
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f1: Atomic structure of the grain boundary.(a) HAADF-STEM image of the GB. (b,c) Atomic resolution EDS elemental maps for (b) Zr K map, (c) Y K maps in the bulk region of the YSZ along [110] direction. Scale bar is 1 nm in (a) and 0.5 nm in (b,c).

Mentions: Figure 1a shows a high angle annular dark-field (HAADF) STEM image of the Σ3[110]/{111} GB. The atomic column intensity in HAADF STEM image is approximately proportional to Z2 (Z represents the atomic number)21, so the bright contrast in the image represents the cation columns intermixed with Zr (Z=40) and Y (Z=39) atoms along this viewing direction. The GB atomic arrangement is in good agreement with the previous high-resolution TEM study20. However, it is impossible to distinguish Zr and Y atoms only from the HAADF STEM image.


Atomically ordered solute segregation behaviour in an oxide grain boundary
Atomic structure of the grain boundary.(a) HAADF-STEM image of the GB. (b,c) Atomic resolution EDS elemental maps for (b) Zr K map, (c) Y K maps in the bulk region of the YSZ along [110] direction. Scale bar is 1 nm in (a) and 0.5 nm in (b,c).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814580&req=5

f1: Atomic structure of the grain boundary.(a) HAADF-STEM image of the GB. (b,c) Atomic resolution EDS elemental maps for (b) Zr K map, (c) Y K maps in the bulk region of the YSZ along [110] direction. Scale bar is 1 nm in (a) and 0.5 nm in (b,c).
Mentions: Figure 1a shows a high angle annular dark-field (HAADF) STEM image of the Σ3[110]/{111} GB. The atomic column intensity in HAADF STEM image is approximately proportional to Z2 (Z represents the atomic number)21, so the bright contrast in the image represents the cation columns intermixed with Zr (Z=40) and Y (Z=39) atoms along this viewing direction. The GB atomic arrangement is in good agreement with the previous high-resolution TEM study20. However, it is impossible to distinguish Zr and Y atoms only from the HAADF STEM image.

View Article: PubMed Central - PubMed

ABSTRACT

Grain boundary segregation is a critical issue in materials science because it determines the properties of individual grain boundaries and thus governs the macroscopic properties of materials. Recent progress in electron microscopy has greatly improved our understanding of grain boundary segregation phenomena down to atomistic dimensions, but solute segregation is still extremely challenging to experimentally identify at the atomic scale. Here, we report direct observations of atomic-scale yttrium solute segregation behaviours in an yttria-stabilized-zirconia grain boundary using atomic-resolution energy-dispersive X-ray spectroscopy analysis. We found that yttrium solute atoms preferentially segregate to specific atomic sites at the core of the grain boundary, forming a unique chemically-ordered structure across the grain boundary.

No MeSH data available.


Related in: MedlinePlus