Abstract：
Achieving a high piezoelectric response and excellent stability is essential for practical applications of ferroelectric materials. Herein, large piezoelectricity of d33 = 167 pC/N and kt = 0.52 is found in a K0.7Na0.3NbO3 lead-free ferroelectric single crystal without poling, which is comparable to the artificially poled KNN crystals. The large piezoelectricity is maintained up to 196 °C, showing excellent thermal stability. It was demonstrated that the high piezoelectricity is associated with strong self-polarization in the crystals. The strong internal stress formed during crystal growth gives a preferred spontaneous polarization orientation, resulting in a net macro total polarization. In addition, the internal stress also pins domain wall motions and provides a \"restoring force\" for the domain switching. This work provides a strategy for designing and optimizing the piezoelectric performance of ferroelectric materials.
摘要：
实现高压电响应和优异的稳定性对于铁电材料的实际应用至关重要。在这里，在没有极化的K0.7Na0.3NbO3无铅铁电单晶中发现d33=167pC/N和kt=0.52的大压电性，与人工极化的KNN晶体相当。大的压电性保持在高达196°C，表现出优异的热稳定性。已证明，高压电与晶体中的强自极化有关。晶体生长过程中形成的强内应力给出了优选的自发极化取向，导致净宏观总极化。此外,内部应力还固定畴壁运动，并为畴切换提供“恢复力”。这项工作为设计和优化铁电材料的压电性能提供了一种策略。
