Tracking ferroelectric domain walls; selenium nanowires; semiconducting silicone.
Researchers from Oak Ridge National Laboratory and National Cheng Kung University developed a technique called scanning oscillator piezoresponse force microscopy to observe how domain walls move in ferroelectric materials under rapidly fluctuating electric fields.
“Domain walls can have completely different properties from the neighboring domains they separate,” said Neus Domingo, a senior R&D staff scientist and group leader for the functional atomic force microscopy group at the Center for Nanophase Materials Sciences (CNMS) at ORNL, in a release. “Some might conduct electricity — despite the bulk material being nonconductive — while others show magnetic behavior despite the surrounding material being nonmagnetic. These differences matter because they may enable us to use them as new nanoelectronic components to store and process signals at the tiniest scales, which is key for developing next-generation low-power devices such as memory chips and sensors.”
“The method fills in crucial gaps by creating dynamic visualizations that allow scientists to observe how domain walls move and better estimate how much energy is required to shift them. It turns a static snapshot into a vivid, explanatory sequence,” added Stephen Jesse, section head of nanomaterials characterization at the CNMS at ORNL, in a release. “Using precisely timed measurement and control electronics, we can rapidly and systematically change the state of a ferroelectric material and watch how changes evolve over time. Until now, this level of detail has not been achieved using atomic force microscopy, and the method can be adapted for use in electron microscopes and other advanced instruments.”
The researchers aim to further refine this technique to study other materials and collaborate with industry partners to explore potential commercial applications. The method is currently available to users at the Center for Nanophase Materials Sciences at ORNL. [1]
Researchers from the University of Nottingham, EPSRC SuperSTEM, Ulm University, and BNNT imaged new forms of selenium using transmission electron microscopy by using nanotubes as tiny test tubes. The nanotubes restricted the selenium, straightening the helical structure and constricting it into atomically thin wires.
“Selenium is an old semiconductor with a rich history, having been used in the first solar cells. In our research, we have revitalized selenium by discovering new forms that can emerge when confined to the nanoscale,” said Will Cull, research fellow in the School of Chemistry, University of Nottingham, in a statement. “To our astonishment, we observed that the nano test tube became thinner as we imaged it! Before our very eyes, we witnessed the selenium nanowire inside the nanotube being squeezed like toothpaste, stretching and thinning. This serendipitous discovery allowed us to establish mechanisms for the transformation of one type of nanowire to another, which have implications for their electronic properties, with near-atomic precision.”
“By utilizing atomically resolved scanning transmission electron microscopy coupled with electron energy loss spectroscopy, we were able to measure the band gaps of individual chains of selenium. These measurements enabled us to establish a relationship between the diameter of these nanowires and their corresponding band gaps,” explained Quentin Ramasse, director of EPSRC SuperSTEM, in a statement. “Traditionally, carbon nanotubes have been used as nano test tubes; however, their outstanding energy absorption properties can obscure the electronic transitions of the material inside. In contrast, a newer type of nano test tube, boron nitride nanotubes, is transparent, allowing us to observe the band gap transitions in selenium nanowires contained within them.” [2]
Researchers from the University of Michigan and Ubon Ratchathani University created a variant of silicone that is a semiconductor. Normally an insulator, silicones are made up of a backbone of alternating silicon and oxygen atoms (Si—O—Si) with organic groups attached to the silicon. However, the team was able to create a silicone copolymer, or a polymer chain containing repeating cage-structured and linear units.
“This allows an unexpected interaction between electrons across multiple bonds including Si—O—Si bonds in these copolymers,” said Richard Laine, U-M professor of materials science and engineering and macromolecular science and engineering, in a press release. “The longer the chain length, the easier it is for electrons to travel longer distances, reducing the energy needed to absorb light and then emit it at lower energies.”
By varying the length of the copolymer chain, the team was able to control the color of light emitted when exposed to a UV light source. Longer chain lengths gave the silicone a red tint, while shorter chains emitted light towards the blue end of the spectrum.
“The material opens up the opportunity for new types of flat panel displays, flexible photovoltaics, wearable sensors, or even clothing that can display different patterns or images,” Laine added. [3]
[1] S. Raghuraman, R. K. Vasudevan, J.-C. Yang, K. P. Kelley, N. Domingo, S. Jesse, Imaging Bias-Driven Domain Wall Motion With Scanning Oscillator Piezoresponse Force Microscopy. Small Methods 2025, 2401565. https://doi.org/10.1002/smtd.202401565
[2] W. J. Cull, Q. M. Ramasse, J. Biskupek, G. A. Rance, I. Cardillo-Zallo, B. L. Weare, M. W. Fay, R. R. Whitney, L. R. Scammell, J. A. Fernandes, U. Kaiser, A. Patanè, A. N. Khlobystov, Flexible Selenium Nanowires with Tuneable Electronic Bandgaps. Adv. Mater. 2025, 2501821. https://doi.org/10.1002/adma.202501821
[3] Z. Zhang, C. Pilon, H. Kaehr, P. Pimbaotham, S. Jungsuttiwong, R. M. Laine, σ–σ* conjugation Across Si─O─Si Bonds. Macromol. Rapid Commun. 2025, 46, 2500081. https://doi.org/10.1002/marc.202500081
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