By Josh Perry, Editor [email protected]
A recent study by researchers at the University of Tokyo (Japan) Institute of Industrial Science has sought to explain the physical principles behind the controllability of crystal lattice organization by creating a model based on the conflict between different lattice interactions.
Researchers have created a model for understanding the principles behind crystal lattice formation and its effect on ferroelectric and antiferroelectric properties. (University of Tokyo)
According to a report by the university, the physical properties of crystal structures is defined by the organization and interactions of the atoms and molecules. For instance, ferroelectric and antiferroelectric behaviors stem from a long-range dipole arrangement of molecules in the lattice.
“Materials exhibiting such order can show electrical switchability, as well as interesting cross-coupling effects; therefore, understanding their behavior has tangible practical benefits,” the report explained.
Researchers varied the shape of the molecules in the lattice and compared the resulting effects on electrical, dynamic, and thermal properties.
“Creating a simple self-organization model based on spherical particles with a permanent dipole allowed the researchers to establish the importance of the energetic frustration between the anisotropic steric and dipolar interactions in the self-organization process,” the article continued.
By understanding the principles behind the particular properties will enable scientists to better control and tune those properties, according to researchers. The model could lead to more “rational design” of materials suited for a variety of applications, including those with specific combinations of electric, magnetic, or thermal properties.
The research was recently published by in Proceedings of the National Academy of Sciences (PNAS). The abstract read:
“Ferroelectricity and antiferroelectricity are widely seen in various types of condensed matter and are of technological significance not only due to their electrical switchability but also due to intriguing cross-coupling effects such as electro-mechanical and electro-caloric effects.
“The control of the two types of dipolar order has practically been made by changing the ionic radius of a constituent atom or externally applying strain for inorganic crystals and by changing the shape of a molecule for organic crystals.
“However, the basic physical principle behind such controllability involving crystal–lattice organization is still unknown. On the basis of a physical picture that a competition of dipolar order with another type of order is essential to understand this phenomenon, here we develop a simple model system composed of spheroid-like particles with a permanent dipole, which may capture an essence of this important structural transition in organic systems.
“In this model, we reveal that energetic frustration between the two types of anisotropic interactions, dipolar and steric interactions, is a key to control not only the phase transition but also the coupling between polarization and strain. Our finding provides a fundamental physical principle for self-organization to a crystal with desired dipolar order and realization of large electro-mechanical effects.”
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