کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9595546 | 1395941 | 2005 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Prediction of compositional ordering and separation in alloy nanoclusters
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Prediction of compositional ordering and separation in alloy nanoclusters Prediction of compositional ordering and separation in alloy nanoclusters](/preview/png/9595546.png)
چکیده انگلیسی
The statistical-mechanical free-energy concentration expansion method (FCEM) in conjunction with semi-empirical coordination-dependent energetic parameters was used for atomistic modeling of Ni-Cu-Al, Ni-Cu-Rh and the corresponding binary Ni-Cu, Ni-Al and Rh-Cu nanocluster systems, containing from 13 to 923 atoms with icosahedral and cuboctahedral shapes. The high efficiency of FCEM enables computations of such relatively large binary or ternary alloy clusters. Remarkable differences, governed by the opposite Ni-Cu and Ni-Al heteroatomic interactions, were noted in the surface segregated “magic-number” ordered compositional patterns of the two ternary clusters. Due to the strong Ni-Al interactions, the compositional ordering extends into the cluster core, and at elevated temperatures a sharp order-disorder transition occurs, depending on the cluster size, shape and composition. The computed site-specific atomic concentrations form the basis for evaluating pertinent thermodynamic functions. For all the alloy clusters a Schottky-type heat capacity anomaly is predicted and attributed to gradual desegregation excitation processes. In addition, inter-cluster compositional separation is computed for Rh-Cu clusters, and transition temperatures estimated from the disappearance of convexity in the free-energy vs. composition curves.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Surface Science - Volume 584, Issue 1, 10 June 2005, Pages 41-48
Journal: Surface Science - Volume 584, Issue 1, 10 June 2005, Pages 41-48
نویسندگان
M. Polak, L. Rubinovich,