A research team led by researcher Li Runwei from the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, proposed a "slight cross-linking" method that can give ferroelectric materials the ability to elastically recover. This breakthrough is called "elastic ferroelectricity" and is expected to promote the development of wearable electronic devices and smart medical care. The research was recently published in the journal Science.
Ferroelectric materials are useful in applications such as data storage and processing, sensing, energy conversion and optoelectronics, making them very popular in mobile phones, tablets and other electronic devices used every day. However, traditional ferroelectric materials have poor elastic recovery after stress release, usually less than 2%, and therefore tend to become brittle (ferroelectric ceramics) or become plastic (ferroelectric polymers).
The ferroelectric properties of these materials are primarily due to their crystalline regions, which lack intrinsic elasticity.
To solve the difficult problem of ferroelectric response and elastic recovery, the researchers developed a precise "light cross-linking" method. The researchers used polyvinylidene fluoride-trifluoroethylene as the matrix material and soft long-chain polyethylene oxide diamine as the cross-linking agent to establish a network structure in the linear ferroelectric polymer. By precisely controlling the cross-linking density at 1-2%, the cross-linked ferroelectric film mainly exhibits a β-phase crystal structure and is evenly dispersed in the cross-linked polymer network.
Under the action of stress, the network structure can be evenly distributed and withstand external forces, thereby mitigating damage to the crystallized region. Therefore, these newly developed ferroelectric materials combine elasticity with relatively high crystallinity. Experimental results also show that the cross-linked film can maintain stable ferroelectric response and elastic recovery even under strains as high as 70%.
"Based on their research, Gao Zhiqiang and others established a new research direction - elastic ferroelectricity." said Professor Xiong Rengen, an internationally renowned expert on ferroelectric materials.
Elastic ferroelectric materials have excellent resistance to mechanical fatigue and ferroelectric fatigue, and have broad application prospects in the fields of wearable electronic devices and smart medical care.