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Disorder-order and order-order phase transformations in Ta5C4 phases predicted using the evolutionary algorithm and
M G Kostenko1, A I Gusev1, A V Lukoyanov2
1Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, Ekaterinburg 620990, Russia. gusev@ihim.uran.ru.
Physical Chemistry Chemical Physics : PCCP
|October 20, 2020
Summary
Researchers discovered four new stable tantalum carbide (TaC0.8) superstructures using evolutionary algorithms. The triclinic Ta5C4 phase is the most stable, offering enhanced melting temperature and hardness for advanced material applications.
Area of Science:
- Materials Science
- Solid State Physics
- Computational Chemistry
Background:
- Nonstoichiometric tantalum carbide (TaC0.8) exhibits complex phase behavior.
- Understanding ordered phases is crucial for predicting material properties.
Purpose of the Study:
- To identify stable ordered phases in nonstoichiometric tantalum carbide (TaC0.8).
- To analyze the properties and phase transition pathways of predicted tantalum carbide superstructures.
Main Methods:
- Utilized evolutionary algorithms and symmetry analysis to search for stable superstructures.
- Calculated Density of States (DOS) to determine electronic properties.
- Determined carbon atom distribution functions and phase transition sequences.
Main Results:
- Predicted four novel stable Ta5C4 superstructures with tetragonal, monoclinic, orthorhombic, and triclinic symmetries.
- All predicted Ta5C4 superstructures and stoichiometric TaC1.00 exhibit metallic conductivity.
- Established physically permissible disorder-order and order-order phase transition sequences for the Ta5C4 family.
- Identified the triclinic Ta5C4 superstructure as the most thermodynamically favorable.
Conclusions:
- The triclinic Ta5C4 superstructure, corresponding to TaC0.80, demonstrates superior melting temperature and hardness.
- These findings provide new insights into tantalum carbide phase stability and properties.
- The predicted superstructures offer potential for advanced material design.
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