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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Structural ordering in Cd(x)Pb(1-x)F2 alloys: a combined molecular dynamics and solid state NMR study
Adalberto Picinin1, Rashmi R Deshpande, Andrea S S de Camargo
1Instituto de Fisica de São Carlos, USP, C.P. 369, 13560-970 São Carlos, São Paul, Brazil.
The Journal of Chemical Physics
|June 17, 2008
Summary
Molecular dynamics simulations reveal that binary cadmium-lead fluoride (Cd(x)Pb(1-x)F(2)) alloys exhibit intrinsic phase segregation. Experimental NMR data confirm this non-statistical distribution, indicating a tendency for PbF(2)-rich domains.
Area of Science:
- Materials Science
- Computational Chemistry
- Solid-State Physics
Background:
- Binary alloys like cadmium-lead fluoride (Cd(x)Pb(1-x)F(2)) are crucial in various applications.
- Understanding their structural properties and phase behavior is essential for material design.
- Eutectic phenomena in alloys are complex and require advanced simulation and experimental techniques.
Purpose of the Study:
- To investigate the structural properties and phase segregation tendencies in Cd(x)Pb(1-x)F(2) alloys using molecular dynamics simulations.
- To analyze the local fluorine environments and their distribution as a function of alloy composition.
- To experimentally validate the simulation predictions using high-resolution (19)F solid-state NMR spectroscopy.
Main Methods:
- Molecular dynamics (MD) simulations employing a two-body Buckingham interaction potential.
- Analysis of simulation data based on five local fluorine environments, Q((n)), defined by Pb nearest neighbors.
- Experimental validation using high-resolution (19)F solid-state NMR spectroscopy on six alloy compositions.
Main Results:
- MD simulations accurately described structural properties and indicated a non-statistical distribution of local fluorine environments.
- The simulations suggested an intrinsic phase segregation tendency in the undercooled melt during cooling.
- NMR data confirmed the non-statistical population distribution and supported the intrinsic segregation of PbF(2)-rich domains, with preferred Q((2)) and Q((4)) formations and substatistical Q((3)) populations.
Conclusions:
- Molecular dynamics simulations provide valuable insights into the behavior of Cd(x)Pb(1-x)F(2) alloys.
- There is strong evidence for an intrinsic phase segregation tendency in these alloys, favoring PbF(2)-rich domains.
- The combination of MD simulations and (19)F NMR spectroscopy offers a powerful approach to understanding alloy microstructures and phase behavior.
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