Very few people have heard of barium titanate, BaTIO3, even though it is used in a wide variety of products from our everyday lives – cars, mobile phones, computers, ultrasound scanners, and for energy conversion. It is a so-called ferroelectric material, whose special properties are used in, for example, capacitors, which can store a large quantity of electrical energy. Ferroelectrics are therefore a popular choice of material in many contexts.
The dynamics and the surface of barium titanate have already been described in detail, but until now the internal structure of the material has been unknown. A new so-called Dark Field X-ray microscope has now made it possible to explore this. The name Dark Field refers to the fact that you do not view the illuminated sample directly under the microscope, but only the scattering from the sample.
Professor Henning Friis Poulsen from DTU Physics is the person behind the development of the new microscope which makes it possible to view movements in the material like a 3D movie with razor-sharp images. The microscope thus allows researchers to view the complex structures deep inside the material and observe how they react when exposed to different loads.
“It’s been great to be able to open a ‘window’ and take a look inside the material. We have focused on two specific areas: the small nuclei and domains that make up the crystals of the BaTIO3 material, and have been able to see how they react when the material is exposed to an electric field,” says Assistant Professor Hugh Simons from DTU Physics, who is responsible for the groundbreaking studies, which have just been published in the prestigious scientific journal Nature Materials.
“It has turned out that the domains’ otherwise symmetrical walls are expanded by several thousandths of a millimetre, thus significantly changing the material’s reaction to the electrical impact. It is a reaction that is up to 1,000 times more powerful than assumed by the last 50 years of research,” says Hugh Simons, who himself was surprised by the finding. He adds: “The new microscope allows us to explore new avenues, which is of course, in itself, incredibly fascinating.”
The new knowledge shows that there is still a need for basic research, and it also opens up for a future development of the application of barium titanate. Hugh Simons thus expects that we – as a result of his study – will see more efficient condensers and thus, for example, better energy utilization in electric cars and ultrasound images with a higher resolution.
The discovery was also a ‘Proof of Concept’ of the method used in the new Dark Field X-ray microscope, which is still under construction at the European ESRF research facility in France, and which is expected to be completed in 2023.