Our research is mainly focused on defect properties in materials using various computational methods. Thermal defects are inevitable in materials. Defects are also the major product in materials under energetic neutron/ion irradiations. Therefore, understanding their properties is critical to alleviating material degradation and further achieving material design for applications in extreme conditions. From point defects such as vacancies and interstitials to line defects such as dislocations, and to planar defects such as grain boundaries and stacking faults, these defects play significant roles in governing phase stabilities, electronic properties and mechanical response of materials.
Defect thermodynamics
Defect energetics, including defect formation energies and migration energies, are fundamental parameters to characterize defect stabilities and defect behaviors. We have carried out extensive ab initio calculations, molecular dynamics, and Kinetic Monte Carlo simulations to investigate defect energetics and thermodynamics in different materials, including ceramics, nanomaterials, metals and concentrated solid-solution alloys. Different kinds of defects are studied, including simple point defects and complex defects such as defect clusters and stacking faults.
Methods
Ab initio calculations
Molecular dynamics simulations
Kinetic Monte Carlo methods
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High-entropy alloys
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Concentrated solid-solution alloys
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Ceramics
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Nanostructures
Defect production
Defects can be produced in various conditions, such as mechanical deformation, energetic ion bombardment or external high-pressure and high-temperature environment. It is, therefore, highly desirable to unveil defect formation mechanisms in order to understand and control defect kinetics. We have studied the threshold energies for defect production in different materials including SiC, carbon nanostructures and concentrated alloys.
Methods
Ab initio calculations
Molecular dynamics simulations
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Concentrated solid-solution alloys
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Ceramics
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Nanostructures
Defect-related properties
The influence of defects on the mechanical and electronic properties of materials is of great importance for practical applications. Using ab initio and molecular dynamics approaches, we have studied how the presence of defects can affect the electronic and mechanical properties of materials.
Methods
Ab initio calculations
Molecular dynamics simulations
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Concentrated solid-solution alloys
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Nanostructures
- Low-dimensional materials