Impact of Grain Size on Piezoelectric Ceramic Performance

Introduction

Piezoelectric ceramics are an important functional ceramic that realize the conversion between electrical and mechanical energy through the piezoelectric effect. They are widely used in fields such as information sensing, medical health, military defense, and aerospace. To date, the most studied piezoelectric materials are piezoelectric ceramics with a perovskite structure.

However, due to the volatility and high toxicity of lead in PZT ceramics, as well as the increasing environmental awareness and the requirements for sustainable social development, significant breakthroughs have been made in the performance of new lead-free piezoelectric ceramics represented by potassium sodium niobate ((K,Na)NbO₃, KNN), sodium bismuth titanate (Na_0.5Bi_0.5TiO₃, BNT), and bismuth ferrite (BiFeO₃, BFO) in recent years. These materials are promising candidates to replace PZT. To this day, high-performance lead-free piezoelectric ceramics have shown performance that even exceeds that of PZT ceramics in applications such as high-power devices and multilayer actuators.

The dielectric, piezoelectric, and ferroelectric properties of piezoelectric ceramics change with the alteration of their grain size, a physical phenomenon known as the grain size effect in piezoelectric ceramics. With the needs of the electronics industry and the development of ceramic preparation technology, piezoelectric devices are trending towards miniaturization, thin-layering, and high integration. The grain size effect of piezoelectric ceramics has also received increasing attention. Some studies indicate that the grain size effect on piezoelectric performance is closely related to the ceramic preparation process, such as preparation methods, sintering processes, and other factors.

This article summarizes the research on the effect of grain size on the piezoelectric performance of BT and PZT, as well as high-performance lead-free piezoelectric ceramics represented by KNN and BNT. It also outlines the methods for controlling grain size in these systems, aiming to provide references for the grain size control of other piezoelectric ceramic systems. Finally, this article points out some difficulties and challenges in the study of the grain size effect on piezoelectric performance in lead-free piezoelectric ceramics, and looks forward to future research directions on the grain size effect on piezoelectric performance (Figure 1).

Content of the Article

Conclusion

This article comprehensively reviews the research progress of the grain size effect on piezoelectric performance in BT, PZT, KNN, and BNT perovskite piezoelectric ceramics, systematically summarizes the methods for controlling grain size in different systems, details the impact of grain size on piezoelectric performance, and elucidates several theoretical mechanisms.

Overall, ferroelectric domains play a key role in the grain size effect of piezoelectric performance in different systems. At the same time, different doping modifications or preparation processes can lead to changes in the phase structure, domain structure, defects, and chemical composition of the material itself. These factors can also affect the response of domains in the material, thereby indirectly impacting the grain size effect on piezoelectric performance. Although the grain size effect on piezoelectric performance varies across different systems, it is undeniable that adjusting grain size is an effective means to regulate its piezoelectric performance. In-depth research on related theoretical mechanisms to promote advancements in grain size control engineering will be a hot direction for future research. We hope this review can help relevant researchers deepen their understanding of the grain size effect on piezoelectric performance in piezoelectric ceramic materials and provide references for further developing high-performance piezoelectric materials.

Source: The Effect of Grain Size on the Piezoelectric Performance of Perovskite-Type Ceramics Liu Yixuan, Li Zhao, Tang Haozheng, Lu Jingtong, Li Jingfeng, Gong Wen, Wang Ke Acta Phys.Sin. Vol.69, No.21 (2020) 217704

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