Details

Autor(en) / Beteiligte

• Tao, Hong
• Wu, Haijun
• Liu, Yao
• Zhang, Yang
• Wu, Jiagang
• Li, Fei
• Lyu, Xiang
• Zhao, Chunlin
• Xiao, Dingquan
• Zhu, Jianguo
• Pennycook, Stephen J

Titel

Ultrahigh Performance in Lead-Free Piezoceramics Utilizing a Relaxor Slush Polar State with Multiphase Coexistence

Ist Teil von

• Journal of the American Chemical Society, 2019-09, Vol.141 (35), p.13987-13994

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Owing to growing environmental concerns, the development of lead-free piezoelectrics with comparable performance to the benchmark Pb­(Zr,Ti)­O3 (PZT) becomes of great urgency. However, a further enhancement of lead-free piezoelectrics based on existing strategies has reached a bottleneck. Here we achieve a slush polar state with multiphase coexistence in lead-free potassium–sodium niobate (KNN) piezoceramics, which shows a novel relaxor behavior, i.e., frequency dispersion at the transition between different ferroelectric phases. It is very different from the conventional relaxor behavior which occurs at the paraelectric–ferroelectric phase transition. We obtain an ultrahigh piezoelectric coefficient (d 33) of 650 ± 20 pC/N, the largest value of nontextured KNN-based ceramics, outperforming that of the commercialized PZT-5H. Atomic-resolution polarization mapping by Z-contrast imaging from different orientations reveals the entire material to comprise polar nanoregions with multiphase coexistence, which is again very different from conventional ferroelectric relaxors which have polar domains within a nonpolar matrix. Theoretical simulations validate the significantly decreased energy barrier and polarization anisotropy, which is facilitated by the high-density domain boundaries with easy polarization rotation bridging the multiphase-coexisting nanodomains. This work demonstrates a new strategy for designing lead-free piezoelectrics with further enhanced performance, which should also be applicable to other functional materials requiring a slush (flexible) state with respect to external stimulus.