کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5425747 | 1395865 | 2006 | 23 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Herringbone and triangular patterns of dislocations in Ag, Au, and AgAu alloy films on Ru(0Â 0Â 0Â 1)
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کلمات کلیدی
Single crystal epitaxy - Epitaxy کریستال تکSurface thermodynamics (including phase transitions) - ترمودینامیک سطح (از جمله انتقال فاز)Metal–metal interfaces - رابط های فلزی فلزیRuthenium - روتنیوم Gold - طلاLow-energy electron microscopy (LEEM) - میکروسکوپ الکترونی کم انرژی (LEEM)Scanning tunneling microscopy - میکروسکوپ تونلی روبشی Silver - نقره
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
We have studied the dislocation structures that occur in films of Ag, Au, and Ag0.5Au0.5 alloy on a Ru(0Â 0Â 0Â 1) substrate. Monolayer (ML) films form herringbone phases while films two or more layers thick contain triangular patterns of dislocations. We use scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) to determine how the film composition affects the structure and periodicity of these ordered structures. One layer of Ag forms two different herringbone phases depending on the exact Ag coverage and temperature. Low-energy electron microscopy (LEEM) establishes that a reversible, first-order phase transition occurs between these two phases at a certain temperature. We critically compare our 1Â ML Ag structures to conflicting results from an X-ray scattering study [H. Zajonz et al., Phys. Rev. B 67 (2003) 155417]. Unlike Ag, the herringbone phases of Au and AgAu alloy are independent of the exact film coverage. For two layer films in all three systems, none of the dislocations in the triangular networks thread into the second film layer. In all three systems, the in-plane atomic spacing of the second film layer is nearly the same as in the bulk. Film composition does, however, affect the details of the two layer structures. Ag and Au films form interconnected networks of dislocations, which we refer to as “trigons.” In 2Â ML AgAu alloy, the dislocations form a different triangular network that shares features of both trigon and moiré structures. Yet another well-ordered structure, with square symmetry, forms at the boundaries of translational trigon domains in 2Â ML Ag films but not in Au films.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Surface Science - Volume 600, Issue 9, 1 May 2006, Pages 1735-1757
Journal: Surface Science - Volume 600, Issue 9, 1 May 2006, Pages 1735-1757
نویسندگان
W.L. Ling, J.C. Hamilton, K. Thürmer, G.E. Thayer, J. de la Figuera, R.Q. Hwang, C.B. Carter, N.C. Bartelt, K.F. McCarty,