The monitoring of grain-boundary grooves in alumina

Munoz, Nicole E.; Gilliss, Shelley R.; Carter, C. Barry

doi:10.1080/09500830310001614487

Cited by 19 publications

(6 citation statements)

References 11 publications

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“…[4][5][6][7] When the temperature is high and the surface energy is isotropic, the groove profile is smooth and agrees well with Mullins's solution. [9][10][11][12] The faceted groove profiles do not agree with Mullins's isotropic model. If the crystallographic orientations of the bicrystal are symmetric about the grain boundary, then the faceted groove profile is also symmetric.…”

Section: Introductionmentioning

confidence: 78%

Grain-boundary grooving by surface diffusion with asymmetric and strongly anisotropic surface energies

Min

Wong

2006

Journal of Applied Physics

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Dirichlet extremum problem associated with the asymmetric grain-boundary thermal grooving under the Dirac δtype anisotropic surface stiffness in bicrystal thin solid films Grain-boundary migration controls grain growth, which is important in material processing and synthesis. When a vertical grain boundary ends at a horizontal free surface, a groove forms at the tip to reduce the combined grain-boundary and surface energies. The groove affects the migration of the grain boundary, and its effect must be understood. This work studies grain-boundary grooving by capillarity-driven surface diffusion with asymmetric and strongly anisotropic surface energies. The surface energies are described by the delta-function facet model that holds for temperatures above the roughening temperature of the bicrystal. Since the asymmetric anisotropy does not introduce a length scale, the asymmetric groove still grows with time t as t 1/4 . Thus, the nonlinear partial differential equation that governs grooving is reduced by a self-similar transformation to an ordinary differential equation, which is then solved numerically by shooting methods. We vary systematically the crystallographic orientations of the bicrystal and the normalized grain-boundary energy. We find that the self-similar groove profile is faceted and asymmetric for most bicrystals. However, a few asymmetric bicrystals can also yield smooth and symmetric grooves. Some bicrystals may even form ridges instead of grooves. We also find that the asymmetric surface energies tilt the grain-boundary tip sideways, which induces the grain boundary to migrate. We show that anisotropic groove profiles measured in SrTiO 3 and Ni can be well fitted by our model.

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Section: Introductionmentioning

confidence: 78%

Grain-boundary grooving by surface diffusion with asymmetric and strongly anisotropic surface energies

Min

Wong

2006

Journal of Applied Physics

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“…Large scale use of YSZ has also been widely reported in oxygen sensors, catalyst support, and high‐temperature coatings and substrate for film deposition or epitaxial growth of oxides . Although, it is well‐known that the specific morphology and physicochemical properties of YSZ surfaces impact a number of mechanical, chemical, and electro‐catalytic functions vital for successful implementation of the material, an in‐depth understanding of the underlying reaction processes remain largely unknown.…”

Section: Introductionmentioning

confidence: 99%

Evolution of porous YSZ surface morphology in YSZ‐MnO_x system

Asadikiya

Zhong

et al. 2018

J Am Ceram Soc

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A unique porous YSZ surface morphology is observed and reported, for the first time, during the sintering of YSZ‐MnO2 composite. The porous YSZ morphology largely depends on YSZ/MnO2 ratio and sintering temperature, time, and atmosphere. The structural evolution is hypothesized to be due to the presence of Mn especially related to Mn diffusion, dissolution, precipitation, and evaporation. A series of experiments were designed and conducted to investigate the porous morphology formation with emphasis on performing quench experiments that showed the initiation of porous surface evolution during cooling. Computational thermodynamics has been applied to investigate the role of Mn on the surface porosity formation.

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“…If the ridge material continued to diffuse away from the groove or if material evaporated during groove formation, then a notch profile, more similar to that shown in Fig. 1(b) for a chemically etched polycrystalline material [22], is expected. The AFM profile in Fig.…”

Section: Grooving By Surface Diffusionmentioning

confidence: 82%

“…The theory predicts two surface maxima, one on each side of the groove. These ridges have been observed experimentally in W [11,12], Fe [13], Pd [14], NiAl [15], Al 2 O 3 [16][17][18], ZrO 2 [19], SrTiO 3 [20], and CeO 2 [21]. MullinsÕ theory describes the development of a thermal-grain-boundary groove by surface diffusion and allows surface diffusion coefficients to be deduced from the geometries of grain-boundary grooves:…”

Section: Grooving By Surface Diffusionmentioning

confidence: 97%