Shanghai Silicate has made progress in the research of new ferroelectric ceramics

[ Instrument R & D of Instrument Network ] Ferroelectric ceramics have the characteristics of high energy storage density, fast discharge speed, stable storage performance, etc., and have important applications in modern science and high-tech fields. The lead zirconate titanate (PZT) series of perovskite structure in traditional ferroelectric materials is a widely used ferroelectric material, and is also an internationally recognized ideal material for energy storage and explosion energy conversion. However, with the increasing demand for new technologies for high-performance ferroelectric materials and the development of an environment-friendly society, it is becoming More and more urgent to explore new lead-free ferroelectric material systems.

Recently, the research team led by Dong Xianlin and Wang Genshui, researchers at the Shanghai Institute of Ceramics, Chinese Academy of Sciences, discovered a new, high-performance, lead-free ferroelectric material (Ag0.935K0.065) NbO3 (AKN). Leaded ferroelectric ceramics have higher energy storage density and better temperature stability, and can be used for energy storage and explosion energy conversion. This work provided an environmentally friendly ferroelectric ceramic material. The relevant research results were published in Science Advances. The first author of the paper was the joint training of doctoral students Liu Zhen, Wang Genshui and Liu Yun by the Shanghai Institute of Ceramics, Chinese Academy of Sciences and Australian National University. The co-corresponding author of the article, Shanghai Silicate Institute is the first unit of the thesis.

Ferroelectric ceramics, ceramic materials whose main crystal phase is ferroelectric. Common ferroelectric ceramics are mostly perovskite-type structures, such as barium titanate ceramics and their solid solutions, as well as tungsten bronze type, bismuth-containing layered compounds and pyrochlore type structures. Principles for determining the formula of ferroelectric ceramics: shift first and then expand, with some emphasis; consider separately and make comprehensive adjustments.

The design of the new material adopts AgNbO3 (AN) as the antiferroelectric phase, and KNbO3 (KN) as the ferroelectric phase to construct the ferroelectric-antiferroelectric phase boundary, and realizes the performance and phase of AKN ferroelectric ceramics by changing the content of the ferroelectric phase KN Variable pressure regulation. Compared with the traditional PZT series ferroelectric ceramics, AKN ferroelectric ceramics have more excellent energy storage density and temperature stability, which makes it have more excellent comprehensive performance in energy storage and explosive energy conversion applications. Through the cooperation with the team of Professor Liu Yun from the Australian National University and the team of Professor Chen Longqing from the Pennsylvania State University in the United States, combined with transmission electron microscopy analysis, in-situ neutron diffraction analysis under pressure and phenomenological theory calculations, the AKN ferroelectric ceramic's explosive transduction behavior was revealed The physical mechanism is that the pressure-induced oxygen octahedral rotation changes from aa-c + type to aac- / aa-c + type, which is related to the pressure-induced, irreversible ferroelectric-antiferroelectric phase transition.

Some dielectrics can be spontaneously polarized. The phenomenon that spontaneous polarization can be reoriented under the action of an external electric field is called the ferroelectric effect. Ceramics with such properties are called ferroelectric ceramics. Ferroelectric ceramics have hysteresis loops and Curie temperatures. At the Curie temperature point, the crystal changes from a ferroelectric phase to a non-ferroelectric phase, and its electrical, optical, elastic, and thermal properties all exhibit abnormal phenomena, such as the maximum value of the dielectric constant. In 1941, the United States first made barium titanate ferroelectric ceramics with a dielectric constant of up to 1100.

Source: Encyclopedia, Shanghai Silicate Research Institute