Guidelines to Exploring Nanoscale Flexoelectricity via AFM Tip Pressing
Guidelines to Exploring Nanoscale Flexoelectricity via AFM Tip Pressing
  • Reporter Yim O-Jung
  • 승인 2022.02.26 21:20
  • 댓글 0
이 기사를 공유합니다



▲Research on AFM tip pressing-driven nanoscale flexoelectricity
▲Research on AFM tip pressing-driven nanoscale flexoelectricity


A Korean research team has developed a method to control the flexoelectricity of nanometer-sized materials by pressing with the AFM tip. A joint team of researchers led by Professor Daesu Lee (PHYS), Prof. Tae Won Noh and Dr. Sung Min Park (Seoul National University), and Prof. Sang Mo Yang (Sogang University) has succeeded in producing flexoelectricity in solids using the atomic force microscopy (AFM) and published a comprehensive guideline that outlines the process for the first time. 
Many components in a smartphone use piezoelectricity to create an electric field. Piezoelectricity is the property of generating an electric field when uniform force is applied to a material in one direction, unlike flexoelectricity. However, since lead zirconate titanate (PZT)—which exhibits high piezoelectricity—contains elements that are harmful to the human body, it has been imperative to develop an alternative material. 
Nanoscale materials that generate flexoelectricity can be used as an alternative. When a non-uniform force is applied to a material, it exhibits spontaneous electrical polarization induced by a strain gradient. This phenomenon is called flexoelectricity. There is no need to apply an electric field when utilizing this property, and therefore, it shows promising device applications in smartphones, generators, and actuators. 
One of the most powerful ways to harness nanoscale flexoelectricity is to press the surface of a material with an AFM tip. However, a comprehensive guideline has not been compiled on this process until now. The complex microscopic effects that appear during the pressing have not been identified either.
To solve this problem, the team came up with a method to control flexoelectricity using the AFM. At the same time, the researchers broadly presented other microscopic phenomena that can appear in addition to flexoelectricity and a methodology for distinguishing flexoelectricity from other phenomena.
Nanoscale materials exhibiting flexoelectricity can not only replace conventional piezoelectric materials but also be used as generators and actuators in nanoscale units. They have the potential to be applied as a photovoltaic cell in which current flows when light is irradiated, a semiconductor, or a catalyst device.