BiFeO₃–BaTiO₃ is a promising lead-free piezoelectric ceramic, exhibiting high Curie temperature and superior electrochemical characteristics. In this work, (1−x)BiFeO₃–xBaTiO₃ (BF–xBT, x=0.26, 0.28, 0.30, 0.32, 0.34, 0.36) ceramics were fabricated using the conventional solid-state reaction method through precise composition control. Multiple characterization techniques, including X-ray powder diffraction (XRD), scanning electron microscope (SEM), and electrical property testing systems, were applied to systematically examine the crystallographic structure, microstructure, as well as the dielectric, ferroelectric and piezoelectric properties of the BF–xBT ceramics. The XRD results confirm that all compositions exhibit a typical perovskite structure, transitioning from a single rhombohedral phase to a rhombohedral–cubic phase mixture as the BT content increases. SEM shows apparent core–shell microstructures in the ceramics. Notably, the results demonstrated that the BF–0.30BT ceramic exhibits the maximum piezoelectric constant (d33) ∼217pC/N, while the BF–0.34BT ceramic displays the maximum converse piezoelectric constant (d33∗)∼323pm/V, which highlights the suitability of BF–BT ceramics for high-performance piezoelectric applications.

Lead zirconate titanate (PZT) ceramics possess great potential for practical applications and thus improving their piezoelectric properties is crucial. Pb0.99?xSm0.01BaxZr0.53Ti0.47O₃ (PSBZT) ceramics with high Curie temperature and excellent piezoelectric properties were fabricated via a conventional solid-state method, and the effect of Ba2+ doping on the structural, dielectric, piezoelectric and ferroelectric properties was studied in detail. It is shown that doping of Ba2+ significantly enhanced the piezoelectric properties of PSZT, the maximum d33～533 pC/N and Tc～361°C at x= 0.02 were acquired. Furthermore, PSZT and PSBZT ceramics were used to prepare single element ultrasonic transducers, and their performance were compared and evaluated. The results demonstrate that the PSBZT ceramic-based transducer possesses better sensitivity and bandwidth than the PSZT ceramic-based transducer.

Ferroelectricity in biological system has been anticipated both theoretically and experimentally over the past few decades. Claims of ferroelectricity in biological systems have given rise to confusion and methodological controversy. Over the years, a “loop” of induced polarization in response to a varying applied electrical field and a consequent polarization reversal has prompted many researchers to claim ferroelectricity in biological structures and their building blocks. Other observers were skeptical about the methodology adopted in generating the data and questioned the validity of the claimed ferroelectricity as such, “loop” can also be obtained from linear capacitors. In a paper with somewhat tongue-in-cheek title, Jim Scott showed that ordinary banana peels could exhibit closed loops of electrical charge which closely resemble and thus could be misinterpreted as ferroelectric hysteresis loops in barium sodium niobate, BNN paraphrasing it as “banana”. In this paper, we critically review ferroelectricity in biological system and argue that knowing the molecular and crystalline structure of biological building blocks and experimenting on such building blocks may be the way forward in revealing the “true” nature of ferroelectricity in biological systems.

基于智能车辆视觉传感器表面除水的需求，该文提出了一种利用压电换能器激励兰姆波以驱动液滴运动的装置，并建立了压电振子和弹性体平板的二维有限元模型。首先运用COMSOL Multiphysics仿真软件对自由边界条件下的压电振子进行频率分析，得到前4阶特征模态，第2阶模态具有最大的结构相对位移，其特征频率为谐振频率；然后对压电振子所激励的兰姆波在平板中的传播特性进行了分析。结果表明，兰姆波在板中出现明显的频散特性，并通过改变压电振子间隔激励A0模态占主导的兰姆波,以提高液滴驱动效果。通过实验验证了兰姆波驱动液滴模型的可行性。

本工作基于高温固相法制备的 ZrO2:Ti4+荧光粉和 PDMS硅橡胶, 获得了一种新型力致余辉发光复合弹性材料, 并通过 XRD、扫描电子显微镜、光谱技术等对荧光粉及弹性体的结构、发光和陷阱性能进行了针对性的表征。结果表明: ZrO2属于单斜晶系, 空间群 P21/c (No.14), 为中心对称结构, 力致发光与常见的压电发光无关, 基质的带隙大约为 5.01 eV, 宽度较大, 有利于发光能级的辐照跃迁, 均匀掺入 Ti4+作为发光中心后, 具有 Ti4+特征发射 eg→t2g的青色的光致及余辉发光, 确定了最强发射时Ti4+的掺杂浓度为0.10%, ZrO2:Ti4+荧光粉与PDMS复合制备的弹性材料在通过 254 nm的紫外灯辐照蓄能后, 可在刮划、撕扯、按压、弯折和拉伸等外力刺激下发出明亮的青色力致发光, 并能在裸眼视觉下持续数秒时间, 该力致余辉现象力光线性依赖且辐照可重复, 在应力可视化、力光传感、工程探测和人造皮肤等领域展现出良好的应用潜力和发展前景, 提出了一种可能的摩擦电引发陷阱载流子激励力致余辉发光的机理。

In this work, we show that a d33～150 pC/N can be obtained in nonpoled poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) copolymer films with an arch structure. The copolymer films, which are often thought to be homogeneous, are in fact inhomogeneous in microstructure and physical properties after film fabrication. Although a large proportion of the copolymer film is nonpolar, as expected in a nonpoled ferroelectric film, the surface regions of the film are spontaneously polarized. We propose that inhomogeneous stress in the surface regions, which is either from the constraint of the substrate or skin layer effect formed during the film fabrication, generates a flexoelectric response and orients the spontaneous polarization of the ferroelectric film. As a result of the polar surface regions, the nonpoled films exhibit a piezoelectric response. The piezoelectric response is further amplified by the special arch structure of the films, leading to the observed large effective piezoelectric response. This study not only discovers the polar surface effect in ferroelectric polymer films, but also proposes an approach to design polymer materials with a strong piezoelectric response.In this work, we show that a d33～150 pC/N can be obtained in nonpoled poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) copolymer films with an arch structure. The copolymer films, which are often thought to be homogeneous, are in fact inhomogeneous in microstructure and physical properties after film fabrication. Although a large proportion of the copolymer film is nonpolar, as expected in a nonpoled ferroelectric film, the surface regions of the film are spontaneously polarized. We propose that inhomogeneous stress in the surface regions, which is either from the constraint of the substrate or skin layer effect formed during the film fabrication, generates a flexoelectric response and orients the spontaneous polarization of the ferroelectric film. As a result of the polar surface regions, the nonpoled films exhibit a piezoelectric response. The piezoelectric response is further amplified by the special arch structure of the films, leading to the observed large effective piezoelectric response. This study not only discovers the polar surface effect in ferroelectric polymer films, but also proposes an approach to design polymer materials with a strong piezoelectric response.

本文通过一步反应合成法制备了铌镁-锆钛酸铅(Pb(Mg1/3Nb2/3)O3-Pb(Zr,Ti)O3, PMN-PZT)压电陶瓷, 研究了稀土元素钐(Sm)掺杂对PMN-PZT(x%(摩尔分数)Sm-PMN-PZT)结构与电学性能的影响规律, 得到了具有高压电性、高机电耦合系数和高居里温度的压电陶瓷。当x=2.0时, 压电常数d33=611 pC/N, 机电耦合系数kp=0.68, 介电损耗tan δ=1.65%,相对介电常数εr=2 650, 居里温度TC=283 ℃。测试压电陶瓷电致应变性能, 在3 kV/mm下单极电致应变达到0.20%, 显示出其大应变材料的特征。结果表明, Sm掺杂PMN-PZT压电陶瓷具有优异的综合电学性能, 有望在换能器、传感器以及致动器等领域广泛应用。

BiFeO3基无铅压电陶瓷常因漏电流较大而压电性能欠佳, 然而, 改善其绝缘性和电性能的方法都较为复杂, 限制了其产业化生产与应用。本工作在不针对0.7BiFeO3-0.3BaTiO3陶瓷进行组分掺杂以及气氛烧结的条件下, 仅通过简单的原料预处理(改变Fe2O3原料的干燥时间)即实现了其高绝缘性与高压电性能。研究结果表明,0.7BiFeO3-0.3BaTiO3陶瓷的晶粒尺寸和绝缘性随Fe2O3原料干燥时间的增加而增大, 同时其电性能及温度稳定性也随之增强。当原料干燥时间为192 h时, 样品晶粒尺寸最大, 绝缘性最好, 同时其压电性能(d33=203 pC/N,kp=0.33)和居里温度(Tc=460 ℃)也达到最佳。这为今后BiFeO3基陶瓷压电性能的研究提供了一个新思路。