Synthesizes Defect Free Nanosheets with Ferroelectric Properties

Scientist from Nagoya UniversityThe Institute for Future Materials and Systems has produced barium titanate (BaTiO3) nanosheets with a thickness of 1.8 nm, the thinnest thickness ever made for a freestanding film.

The creation of the thinnest freestanding films with ferroelectric properties opens the door to smaller and more efficient devices. Image Credit: Dr Minoru Osada.

Because thickness connects to functionality, their findings set the stage for smaller, highly effective devices. This study is reported in the journal Advanced Electronic Materials.

The creation of ever thinner materials with new electronic functions is recognized as a highly competitive research area. Such devices are important in ferroelectrics, materials whose polarization can be reversed by an electric field. This potential to reverse polarization makes the material useful in memory and vibrational power generation.

But because the materials in these devices turned out to be smaller, they showed sudden properties that confused their industrial use. The big problem is the “size effect”, because when the thickness of the material is reduced to a few nm, its ferroelectric properties are lost.

A research group from the Department of Materials Chemistry of Nagoya University and the Institute of Materials and Systems for Sustainability (IMASS), led by Professor Minoru Osada (he), has successfully synthesized a defect-free BaTiO3 nanosheets with ferroelectric properties at a thickness of about 1.8 nm using the aqueous solution process.

The result is the thinnest free-standing film ever made. Despite being thin, the films display ferroelectric properties, highlighting significant discoveries in the manufacture of thin films and active ferroelectrics.

However, for BaTiO3, a typical ferroelectric material, it is difficult to synthesize nanosheets by conventional synthetic methods. Therefore, it is necessary to develop new synthetic methods. Generally, the synthesis of BaTiO3 requires a calcination process that requires a temperature of 1000 °C or higher.

Minoru Osada, Professor, University of Nagoya

Osaada added,Instead, we synthesized BaTiO3 nanosheets at a low temperature of 60 °C using our process. Since the film thickness can be controlled using this method by varying the reaction time, the synthesis of nanosheets with two to six lattices is achieved..”

If nanosheets with a thickness of several nanometers can be synthesized in ferroelectrics, new properties and applications are expected to be discovered. Our findings should provide important techniques for miniaturization of devices such as memory and capacitors,” continued Osada.

As existing technologies have reached their limits in both materials and processes, engineering like ours is essential. They offer dramatic improvements in performance and technological innovation through new materials and processes.

Minoru Osada, Professor, University of Nagoya

Journal Reference

Hagiwara, K., et al. (2023) Molecularly Thin BaTiO23 Nanosheets with Stable Ferroelectric Response. Advanced Electronic Materials.


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