Researchers at the Faculty of Materials Science and Engineering at the Technion succeeded in changing the electrical properties of a material by removing an oxygen atom from the original structure. Possible applications: electronic miniaturization and detection of radiation emissions
What do imaging of a fetus in an ultrasound device, cellular communication in mobile devices, tiny motors and computer memories that operate on little energy have in common? All these technologies are based on Ferroelectric materials - Materials characterized by a strong connection between the structure of the atoms in the material and its electrical and mechanical properties.
Now, researchers at the Technion have succeeded in changing the properties of ferroelectric materials by Elimination of a single oxygen atom from the original structure. In doing so, they are breaking ground for the development of new technologies. led the research Dr. Yachin Ivri from the Faculty of Materials Science and Engineering with the postdoctoral student Dr. Hamparava Halengovan and the doctoral student Mia Barzilai, and it was published inDHW Nano. It is worth noting that removing an oxygen atom from its place is a great challenge due to the tiny weight of the oxygen atoms, so the aforementioned achievement is particularly impressive.
In ferroelectric materials, a small displacement of the atoms causes significant changes in the electric field and in the contraction or expansion of the material. This effect is due to the fact that the basic repeating unit in the material includes atoms arranged in a non-symmetrical structure.
To clarify the last sentence, we will take as an example a ferroelectric material called barium titanate. In this material, the atoms form a cube-like structure, inside which are one titanium atom and oxygen atoms. A unique phenomenon occurs in these materials: the titanium atom moves away from the oxygen atoms. Since titanium has a positive electric charge and oxygen a negative charge, their distance from each other creates polarization, that is, an electric dipole.
The cube has six faces, so the charged atoms move to one of six possibilities. In different regions of the material, a large number of neighboring atoms move in the same direction and the polarization in each such region, known as a ferroelectric domain, is uniform.
The traditional technologies are based on the electric field created in those areas. However, in recent years a tremendous effort has been made to minimize the devices and make use oflimit between the domains instead of in the domains themselves, thus transforming the devices from XNUMXD structures to XNUMXD structures. Researchers are still divided about what happens in the two-dimensional world of the domain walls: how is the boundary between two regions of different electric polarization stabilized? Does the domain walls have a different electric polarization than the domains themselves? Is it possible to control the properties of the domain walls in a point-by-point manner?
In the study, the researchers were able to decipher, on the atomic scale, the structure of the atoms and the arrangement of the electric field in the walls of the domains. In an article in ACS Nano, the researchers confirm the hypothesis that the domain walls enable the existence of a two-dimensional border between domains as a result of some of the oxygen atoms in the areas shared by two domains leaving the material, thus allowing greater flexibility in the arrangement of the local electric field. The researchers were able to "disappear" a single oxygen atom, and showed that this operation creates inverted dipoles and higher electrical symmetry - a unique topological structure called a quadrupole.
With the help of computer simulations conducted by Li Xiu of Westerlake University in China, the researchers showed that the removal of the oxygen atom has a great effect on the electrical properties of the material not only on the atomic scale but also on a scale relevant to electronic devices - for example in the aspect of electrical conductivity. This means that this scientific achievement may help in the miniaturization of such devices.
Furthermore, in collaboration with researchers from the Negev Nuclear Research Institute, the Technion researchers showed that the elimination of the oxygen atom can be achieved by exposing the material to electron radiation. Therefore, in addition to the technological potential of the discovery in the field of electronics, it is possible to use the effect for radiation detector And by doing so, to locate in advance and thus prevent nuclear malfunctions such as the disaster that befell the reactor in Fukushima a few years ago.
The research, which was carried out in the microscopy facilities at the Faculty of Materials Science and Engineering, was funded by the Israel Science Foundation and the Pezzi Foundation. The Laboratory for Functional Nano and Quantum Structures, headed by Dr. Evari, operates with the support of the Zuckerman Program for Leadership in Science and Technology.
For an article in ACS Nano click here
