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Ab initio study of phase equilibria in TiC(x).
P A Korzhavyi1, L V Pourovskii, H W Hugosson
1Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
Physical Review Letters
|January 22, 2002
Summary
This study establishes the phase diagram for substoichiometric titanium carbide (TiC(x)) using Monte Carlo simulations. It identifies three stable vacancy-ordered superstructures as ground states, crucial for understanding material properties.
Area of Science:
- Materials Science
- Computational Materials Science
- Solid-State Chemistry
Background:
- Substoichiometric titanium carbide (TiC(x)) exhibits complex vacancy ordering.
- Understanding these ordered structures is critical for predicting material properties and performance.
Purpose of the Study:
- To establish the phase diagram for vacancy-ordered structures in TiC(x) (x = 0.5-1.0).
- To identify the ground state configurations of vacancies within the TiC(x) lattice.
Main Methods:
- Monte Carlo simulations were employed to explore the phase space.
- Long-range pair and multisite effective interactions, derived from ab initio calculations, were utilized.
- Full-potential total energy calculations were performed to verify the stability of identified structures.
Main Results:
- The phase diagram reveals three distinct ordered superstructures of vacancies: Ti(2)C, Ti(3)C(2), and Ti(6)C(5).
- These three superstructures were identified as the ground state configurations under the simulated conditions.
- Stability of these ground states was confirmed through rigorous total energy calculations.
Conclusions:
- The established phase diagram provides a fundamental understanding of vacancy ordering in substoichiometric TiC(x).
- The identified ground state structures are key to the material's stability and potential applications.
- This work offers a predictive framework for designing TiC(x) materials with desired properties.