Perovskite materials based on BiFeO₃-PbTiO₃ (BFPT) solid solutions are promising for various applications thanks to the extremely large spontaneous polarization (P_s) and existence of multiferroic morphotropic phase boundary. For applications in piezoelectric and memory devices, complete switching of P_s is needed, which is hard to achieve practically. In this work, a simple modified mixed-oxide reaction method is developed allowing to prepare Dy- and Sm-modified BFPT ceramics with significantly improved properties. The MPB compositions demonstrate well-saturated ferroelectric hysteresis loops with large switchable remanent polarization of 60 µC cm⁻² and enhanced piezoelectric properties with a large-signal piezoelectric coefficient d₃₃* = 214 pm V⁻¹ and a direct piezoelectric coefficient d₃₃ = 128 pC N⁻¹, which is one and a half times larger than the best d₃₃ value reported for the BFPT ceramics so far. The Curie temperature reaches 539 °C, suggesting a potential for high-temperature applications. The domain structure is studied by piezoresponse force microscopy. It is found that the enhanced dielectric/piezoelectric properties are mainly due to polarization rotation/extension (intrinsic) mechanism, while the extrinsic contributions of the interphase and domain walls are virtually absent. The strategies for improvement of properties of BFPT and related materials are proposed.

中文翻译：

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在 BiFeO3-PbTiO3 固溶体陶瓷中实现大的可切换极化和增强的压电响应

基于BiFeO _{3 -PbTiO 3} (BFPT)固溶体的钙钛矿材料由于具有极大的自发极化( P _s )和多铁同形变相边界的存在而具有广泛的应用前景。对于压电和存储器件的应用，需要完全切换P _s，这在实际中很难实现。在这项工作中，开发了一种简单的改性混合氧化物反应方法，可以制备性能显着改善的 Dy 和 Sm 改性 BFPT 陶瓷。MPB 组合物表现出良好饱和的铁电磁滞回线，具有 60 µC cm ^{-2的大可切换剩余极化}和增强的压电特性，大信号压电系数d ₃₃ * = 214 pm V ^-1和直接压电系数d ₃₃  = 128 pC N ^-1，比最佳d _{33大一倍半}迄今为止报道的BFPT陶瓷的值。居里温度达到 539 °C，表明具有高温应用的潜力。通过压电响应力显微镜研究域结构。发现增强的介电/压电性能主要是由于极化旋转/扩展（本征）机制，而界面和畴壁的外在贡献几乎不存在。提出了改善BFPT及相关材料性能的策略。