What's that swirly pattern? It's a moiré, and it has potential power
Just as wave-like patterns can appear on a computer screen when pixels do not align, new research led by Flinders University is investigating atomic-scale "moiré patterns" in the promising field of ferroelectricity. The new study, with experts at Monash University and Nanyang Technological University in Singapore, seeks inroads into electrical and optical science by exploring these complex "superlattice" patterns in various ways to create new energy and material capabilities.
"Similar to the pixel example, we can overlay single-atom thin layers in non-aligned ways to achieve physical properties not present in regular repetitive materials—including superconductivity, special insulating and conductive states, and ferroelectricity," says Dr. Pankaj Sharma, from the Institute for Nanoscale Science and Technology at Flinders University.
Scientists have discovered that ordinary ice is a flexoelectric material, capable of generating electricity when bent or unevenly deformed.
"Frozen water is one of the most abundant substances on Earth. It is found in glaciers, on mountain peaks and in polar ice caps. Although it is a well-known material, studying its properties continues to yield fascinating results.
An international study involving ICN2, at the UAB campus, Xi'an Jiaotong University (Xi'an) and Stony Brook University (New York), has shown for the first time that ordinary ice is a flexoelectric material. In other words, it can generate electricity when subjected to mechanical deformation. This discovery could have significant implications for the development of future technological devices and help to explain natural phenomena such as the formation of lightning in thunderstorms.
The study, published in the journal Nature Physics, represents a significant step forward in our understanding of the electromechanical properties of ice. "We discovered that ice generates electric charge in response to mechanical stress at all temperatures. In addition, we identified a thin 'ferroelectric' layer at the surface at temperatures below -113ºC (160K). This means that the ice surface can develop a natural electric polarization, which can be reversed when an external electric field is applied -- similar to how the poles of a magnet can be flipped. The surface ferroelectricity is a cool discovery in its own right, as it means that ice may have not just one way to generate electricity but two: ferroelectricity at very low temperatures, and flexoelectricity at higher temperatures all the way to 0 °C " explains Dr Xin Wen, a member of the ICN2 Oxide Nanophysics Group and one of the study's lead researchers. This property places ice on a par with electroceramic materials such as titanium dioxide, which are currently used in advanced technologies like sensors and capacitors.
One of the most surprising aspects of this discovery is its connection to nature. The results of the study suggest that the flexoelectricity of ice could play a role in the electrification of clouds during thunderstorms, and therefore in the origin of lightning."
Prototype thermal memory stores heat states with tiny voltages for days
Heat is a ubiquitous form of energy that, unlike others, is notoriously difficult to store due to its natural tendency to dissipate. While this property is essential for phenomena like solar energy reaching Earth, it also poses a significant technological challenge.
Instead of attempting to confine heat, a team of researchers from the Center for Research in Biological Chemistry and Molecular Materials (CiQUS), in collaboration with the University of Barcelona and the University of Zaragoza, has proposed an alternative strategy: harness heat where it is generated, controlling its flow in real time and using it to develop thermal memory devices.
In a study published in Advanced Materials, the team introduces a prototype thermal memory device capable of switching between different thermal conductivity states through the application of small electric voltages.
A roadmap for atomic force microscopy use in next-generation semiconductor and energy materials research
For smartphones and computers to become smaller and faster, technologies capable of precisely controlling electrical properties at the nanoscale—beyond what is visible to the naked eye—are essential. In particular, ferroelectric materials, which can maintain their electrical state without external power, are gaining attention as key components for next-generation memory and sensor technologies. However, due to their extremely small size, there have been limitations in precisely observing the internal changes occurring within these materials.
New review maps AFM-based strategies
A research team led by Professor Seungbum Hong from the Department of Materials Science and Engineering has published a review paper in the Journal of Materials Chemistry C systematically outlining research strategies for ferroelectric materials based on atomic force microscopy (AFM), addressing these limitations.
Helical liquid crystals can flip light's chirality under ultralow electric fields
The direction in which the electromagnetic field of circularly polarized light rotates can be easily reversed by applying a voltage, RIKEN researchers have demonstrated. This could enable a new generation of optical devices based on circularly polarized light. The work is published in two papers in the journal Advanced Materials.
Why circular polarization matters
Polarized sunglasses produce light that is polarized along a single direction. But some special devices can generate light with a polarization that rotates as the light propagates. Such circularly polarized light is useful for many applications, including spectroscopy, satellite communications, stereoscopy and microscopy.
Focused helium ions create ferroelectric regions in aluminum nitride for lower-power chips
Scientists at the Department of Energy's Oak Ridge National Laboratory have shown for the first time that ferroelectricity can be directly written into aluminum nitride using a tightly focused helium ion beam at the Center for Nanophase Materials Sciences (CNMS), a DOE Office of Science user facility at ORNL. Ferroelectric devices don't need constant power to store data, which allows for devices that are more reliable and less power consuming than what's currently available.
The study, published in Advanced Materials, represents a new processing approach for wurtzite III-V nitrides, a class of semiconductors already widely used in microelectronics but whose ferroelectric potential has only been recognized since 2019.
Hidden 3D atomic structure of relaxor ferroelectrics revealed for first time
Materials called relaxor ferroelectrics have been used for decades in technologies like ultrasounds, microphones, and sonar systems. Their unique properties come from their atomic structure, but that structure has stubbornly eluded direct measurement.
Now a team of researchers from MIT and elsewhere has directly characterized the three-dimensional atomic structure of a relaxor ferroelectric for the first time. The findings, reported in Science, provide a framework for refining models used to design next-generation computing, energy, and sensing devices.
"Now that we have a better understanding of exactly what's going on, we can better predict and engineer the properties we want materials to achieve," says corresponding author James LeBeau, MIT's Kyocera Professor of Materials Science and Engineering.
Researchers from the Institute of Metal Research (IMR) of the Chinese Academy of Sciences have developed a new ferroelectric ultraviolet photodetector material that overcomes the long-standing performance limitations of conventional photodetectors.
This breakthrough, published in Nature Communications, promises to enable next-generation optical detection with ultra-fast speed, high sensitivity, and low noise across a wide range of applications.
Photodetectors convert light signals into electrical currents and are fundamental to modern optoelectronics. They are essential for technologies such as high-speed optical communications, environmental monitoring, and space exploration. However, creating a material that possesses all three of these qualities has been a significant challenge.
