کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9594511 | 1507964 | 2005 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Barriers to shape evolution of supported nano-crystallites
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کلمات کلیدی
Surface diffusion - انتشار سطحEquilibrium thermodynamics and statistical mechanics - ترمودینامیک تعادل و مکانیک آماریNon-equilibrium thermodynamics and statistical mechanics - ترمودینامیک غیر تعادل و مکانیک آماریClusters - خوشهLead - سربStepped single crystal surfaces - سطوح کریستالی پله شدهNucleation - هستهAdhesion - چسبندگی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Continuum solutions for supported crystallite shapes are combined with the continuum step model to yield a quantitative description of the physically-allowed metastable states, including the dependence on interfacial adhesion energy. Using a model of layer-by-layer shape evolution, the activation barriers for transitions between metastable states are calculated. The results collapse to a universal scaled form and for which the barrier height decreases (increases) for metastable states taller (shorter) than the equilibrium structure. Following Rohrer and Mullins [W.W. Mullins, G.S. Rohrer, Journal of the American Ceramic Society 83 (2000) 214; G.S. Rohrer, C.L. Rohrer, W.W. Mullins, Journal of the American Ceramic Society 84 (2001) 2099], we evaluate the smallest crystal volume where the energy barrier is less than 10kBT as a function of the metastable state and interfacial energy. The results yield a family of curves showing the lowest energy accessible structure as a function of the dimensionless volume for different adhesions energies. Increasing adhesion energy correlates with increasing activation barriers at the same volume. Using realistic parameters for Pb, the equilibrium structure can only be reached by peeling for volumes ⩽50 nm3, and crystals of volume ⩾106 nm3 will be trapped in the least favorable metastable state.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Surface Science - Volume 595, Issues 1â3, 5 December 2005, Pages 87-96
Journal: Surface Science - Volume 595, Issues 1â3, 5 December 2005, Pages 87-96
نویسندگان
M. Degawa, E.D. Williams,