This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: All materials contain inherent defects. These are not always harmful, since they can be used to engineer and introduce certain properties into a material.
However, it is crucial to understand how they function and how they affect the material's properties. To understand and model defects in different materials, researchers' standard calculations are usually based on zero Kelvin, minus 273 degrees Celsius, the theoretically lowest possible temperature at which all atoms and molecules are completely stationary. But for materials intended for use in real-world products and everyday applications, it is essential to know how they behave at ordinary temperatures.
Researchers at Chalmers University of Technology have now demonstrated a significantly more effective framework for calculating the properties of defects while accounting for different temperature effects, enabling results that are much closer to reality. The findings are presented in an article published in npj Computational Materials. Julia Wiktor, a professor at the Department of Physics and Astronomy, leads the research group behind the study.
Their work focuses on studying and modeling new materials using advanced computer simulations and machine learning. "We usually model materials as perfect crystals where every atom occupies a fixed position in a lattice, but real materials are not so perfect. An atom may be missing, there may be an extra atom between lattice sites, or two atoms may have swapped places.
We need to understand these imperfections because they affect the performance and function of materials," says Wiktor. The materials the research group typically investigates are mainly within solar cell technology, but this time they used a broader set of benchmark systems to test whether the method could be applied to other material classes and emerging technologies. "We modeled defects in the materials by studying a missing atom in the crystal structure and observing how temperature affects the behavior of this point defect," says doctoral student Tobias Hainer.
"This is something that most models and simulations based on zero Kelvin fail to capture, and it is an important step toward understanding how different materials actually behave under real operating conditions. Our results match experimental observations, but unlike experiments we do not just obtain an initial and a final measurement—we can follow the defect throughout the entire temperature range." Defects can often introduce new energy levels into materials. A semiconductor, for example, has a so-called band gap, meaning an energy interval without available electronic states, and defects can introduce different levels within this gap.
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