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Structural selection and amorphization of small Ni-Ti bimetallic clusters.
H B Liu1, G Canizal, P S Schabes-Retchkiman
1Programa de Investigación en Ductos, Corrosion y Materiales, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, Col. San Bartolo Atepehuacan, C.P. 07730, Mexico DF, Mexico.
The Journal of Physical Chemistry. B
|June 28, 2006
Summary
Nickel-titanium (Ni-Ti) bimetallic nanoclusters under 3 nm are not energetically stable in ordered structures. Experimental and simulation results show separate elemental aggregation and structural amorphization in some configurations.
Area of Science:
- Materials Science
- Nanotechnology
- Computational Chemistry
Background:
- Bimetallic nanoclusters are crucial in various applications.
- Understanding the structural stability and elemental distribution of Ni-Ti nanoclusters is essential for their technological use.
- Bioreduction offers a novel synthesis route for these nanomaterials.
Purpose of the Study:
- To investigate the structural and thermodynamic properties of Ni-Ti bimetallic nanoclusters.
- To analyze the elemental distribution and stability of different Ni-Ti nanocluster configurations.
- To correlate simulation findings with experimental observations of biosynthesized nanoparticles.
Main Methods:
- Classical molecular dynamics simulations were employed for structural and thermodynamic analysis.
- Nanoclusters were synthesized using a bioreduction method.
- Transmission electron microscopy (TEM) was used for experimental characterization.
Main Results:
- Ni-Ti nanoclusters (2-3 nm) do not favor common ordered geometries (cuboctahedron, decahedron, icosahedron).
- Nickel and titanium elements tend to segregate within the nanoclusters.
- Eutectic-like and Ni-core/Ti-shell structures exhibit stability at room temperature, while solid solution and Ti-core/Ni-shell structures tend to amorphize.
- Experimental TEM analysis confirmed partially amorphized structures and cubic/twinned-like morphologies.
Conclusions:
- Small Ni-Ti bimetallic nanoclusters are energetically unstable in ordered forms.
- Elemental segregation and structural amorphization are significant factors influencing Ni-Ti nanocluster stability.
- Bioreduction synthesis yields nanoparticles with characteristics consistent with simulation predictions of structural instability.