So you thought antiferroelectric materials were always non-polar? Think again!
What exactly are antiferroelectric materials, and what does it mean that they can also be polar? The answers may open up new possibilities in technology.
Researchers are now identifying materials that combine properties previously thought to be mutually exclusive. This could lead to new technological applications.
Many of the advanced electronic components surrounding us in everyday life rely on polar materials to function.
Polar materials have an uneven distribution of electric charge. This gives them a positive and a negative side even in the absence of an external electric field. The most important among these are ferroelectric materials, in which the direction of polarization can be reversed by applying an electric field.
What do these terms mean?
- Ferroelectric materials contain large numbers of tiny electric dipoles. Nearly all of these dipoles point in the same direction, creating an overall electric polarization. One end of the material becomes positively charged and the other negatively charged. Importantly, the direction of this polarization can be reversed by applying an electric field. These materials are commonly used in capacitors, ultrasound sensors, certain memory devices, and related technologies.
- Antiferroelectric materials are also technologically useful. They likewise contain large numbers of tiny electric dipoles, but these dipoles point alternately in opposite directions. As a result, they cancel each other out, producing no overall electric polarization. These materials are particularly well suited for storing large amounts of energy that must be released rapidly.
- The newly studied material combines properties of both ferroelectric and antiferroelectric materials, while also exhibiting hybrid properties that are unusual for either class.
Antiferroelectric materials
Dennis Meier. Photo: Thor Nielsen, NTNU
Antiferroelectric materials are different. They exhibit an alternating up-down arrangement of tiny electric dipoles. These materials possess unique properties that can be exploited in applications such as energy storage and novel cooling technologies.
Until recently, however, researchers believed that such materials could not also be polar.
“Unfortunately, these electric dipoles cancel each other out, making the antiferroelectric material non-polar. This limits their potential applications in a broader context,” says Dennis Meier.
Meier is an adjunct professor at the Department of Materials Science and Engineering at NTNU. He is involved in two research papers, one published in Nature Materials and the other in Nature Nanotechnology.
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Materials that break the rules
But does a material really need to have this strict up-down arrangement to retain its antiferroelectric properties?
“For many years, researchers assumed this was the case, although several scientists discussed more complex patterns,” says researcher Ivan Ushakov of the Department of Materials Science and Engineering. He is the lead author of one of the papers.
These more complex patterns can range from simple tilts and irregularities in the up-down arrangement to waves and spirals. Combinations of several patterns are also possible.
“Our findings show that this cancellation is not always necessary after all. This means that antiferroelectric materials represent a much broader and richer class of materials than previously assumed. It requires a redefinition of the entire concept,” says Dennis Meier.
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Formed complex patterns instead
One example is the compound K₃[Nb₃O₆|(BO₃)₂], which has long been known to exhibit indications of both polar and antiferroelectric properties.
Ivan Ushakov. Photo: Kai T. Dragland, NTNU
“In this material, the up-down pattern is not completely cancelled out because of a slight tilt. By examining the structure in detail, we have identified the exact mechanisms that make it possible for both ferroelectricity and antiferroelectricity to coexist in a single material,” says Ivan Ushakov.
Surprisingly, the compound turns out not only to combine properties of ferroelectric and antiferroelectric materials. By taking a closer look at the electrically controllable regions, known as domains, the researchers found that the material also exhibits unique “hybrid” properties.
“Using advanced microscopy, we observe that the domains are separated by highly extended and extremely thin boundaries with properties that are very unusual compared with similar boundaries in both classical ferroelectric and antiferroelectric materials,” says Dennis Meier.
The work points toward a new class of materials whose electrical properties no longer fit into a single category.
Such hybrid systems could open up new opportunities in energy storage, sensors, and other electronic technologies, while at the same time forcing a reconsideration of what antiferroelectricity actually is.
References: Ushakov, I.N., Topstad, M., Khalid, M.Z. et al. Hybrid antiferroelectric–ferroelectric domain walls in noncollinear antipolar oxides. Nature Nanotechnology 21, 648–654 (2026). https://doi.org/10.1038/s41565-026-02139-8
Catalan, G., Gruverman, A., Íñiguez-González, J. et al. A modern perspective on antiferroelectrics. Nature Materials 25, 557–565 (2026). https://doi.org/10.1038/s41563-026-02483-z
