Photoacoustic microscopy (PAM), due to its deep penetration depth and high contrast, is playing an increasingly important role in biomedical imaging. PAM imaging systems equipped with conventional ultrasound transducers have demonstrated excellent imaging performance. However, these opaque ultrasonic transducers bring some constraints to the further development and application of PAM, such as complex optical path, bulky size, and difficult to integrate with other modalities. To overcome these problems, ultrasonic transducers with high optical transparency have appeared. At present, transparent ultrasonic transducers are divided into optical-based and acoustic-based sensors. In this paper, we mainly describe the acoustic-based piezoelectric transparent transducers in detail, of which the research advances in PAM applications are reviewed. In addition, the potential challenges and developments of transparent transducers in PAM are also demonstrated.

MnO2-modified Pb0.9625Sm0.025(Mg1/3Nb2/3)0.71Ti0.29O3 ceramics were prepared via a solid-state reaction approach. Results of detailed characterizations revealed that the addition of MnO2 has influence on the grain size, and all samples exhibit a pure perovskite structure. As the content of manganese increases, the volume of tetragonal phase increases. The ceramics with 1.5 mol.% MnO2 show a high electro-strain of 0.151% at 2 kV/mm. Therefore, this study provides a new insight into the role of MnO2 addition in tailoring the electrical properties of the Sm-PMN-PT ceramics by acceptor doping.

Relaxor-based ternary Pb(In1/2Nb1/2)O₃–Pb(Mg1/3Nb2/3)O₃–PbTiO₃ (PIN–PMN–PT) single crystals and ceramics are promising candidates for high-performance electromechanical conversion devices. It is known that the domain structure and dielectric diffusion–relaxation characteristics are crucial to the excellent performances of relaxor ferroelectrics. In this work, we prepared the PIN–PMN–PT ceramics with various PIN/PMN proportions and systematically investigated their domain structure and dielectric diffusion–relaxation properties. The effect of PIN/PMN proportion on the domain size and dielectric diffusion–relaxation characteristics was also studied. The investigations showed that PIN–PMN–PT ceramics presented multi-type domain patterns comprising irregular island domains and regular lamellar domains. Moreover, the dependent relations of PIN/PMN proportions on the dielectric diffusion and domain size indicated that the PIN composition has a stronger lattice distortion than PMN composition; increasing the PIN proportion can enhance the dielectric diffusion and decrease the domain size. Our results could deepen the understanding of structure–property relationships of multicomponent relaxor ferroelectrics and guide the design and exploration of new high-performance ferroelectric materials.Relaxor-based ternary Pb(In1/2Nb1/2)O₃–Pb(Mg1/3Nb2/3)O₃–PbTiO₃ (PIN–PMN–PT) single crystals and ceramics are promising candidates for high-performance electromechanical conversion devices. It is known that the domain structure and dielectric diffusion–relaxation characteristics are crucial to the excellent performances of relaxor ferroelectrics. In this work, we prepared the PIN–PMN–PT ceramics with various PIN/PMN proportions and systematically investigated their domain structure and dielectric diffusion–relaxation properties. The effect of PIN/PMN proportion on the domain size and dielectric diffusion–relaxation characteristics was also studied. The investigations showed that PIN–PMN–PT ceramics presented multi-type domain patterns comprising irregular island domains and regular lamellar domains. Moreover, the dependent relations of PIN/PMN proportions on the dielectric diffusion and domain size indicated that the PIN composition has a stronger lattice distortion than PMN composition; increasing the PIN proportion can enhance the dielectric diffusion and decrease the domain size. Our results could deepen the understanding of structure–property relationships of multicomponent relaxor ferroelectrics and guide the design and exploration of new high-performance ferroelectric materials.

A series of (100−x)Pb(Mg1/3Nb2/3)O3−xPbTiO₃ (PMN−xPT, x= 24, 25, 26) ceramics were prepared by solid-state reaction technique using MgNb₂O₆ precursor. The results of the detailed characterizations reveal that the content of PT has negligible influence on the grain size, and all samples possess the perovskite structure. As the PT content increases, the samples changed from the normal ferroelectric phase to the ergodic relaxor state at room temperature. As a result, PMN–xPT ceramics are endowed with electro-strain of 0.08% at a relatively low electric field of 2 kV/mm, and effective piezoelectric coefficient of 320 pm/V was obtained. Simultaneously, the PMN–xPT ceramics have exceptional pyroelectric performance, exhibiting a high pyroelectric coefficient p∼5.5 – 6.3 × 10−8 C⋅cm−2⋅K−1. This study demonstrates the great potential of PMN–xPT for piezoelectric and pyroelectric device applications.A series of (100−x)Pb(Mg1/3Nb2/3)O3−xPbTiO₃ (PMN−xPT, x= 24, 25, 26) ceramics were prepared by solid-state reaction technique using MgNb₂O₆ precursor. The results of the detailed characterizations reveal that the content of PT has negligible influence on the grain size, and all samples possess the perovskite structure. As the PT content increases, the samples changed from the normal ferroelectric phase to the ergodic relaxor state at room temperature. As a result, PMN–xPT ceramics are endowed with electro-strain of 0.08% at a relatively low electric field of 2 kV/mm, and effective piezoelectric coefficient of 320 pm/V was obtained. Simultaneously, the PMN–xPT ceramics have exceptional pyroelectric performance, exhibiting a high pyroelectric coefficient p∼5.5 – 6.3 × 10−8 C⋅cm−2⋅K−1. This study demonstrates the great potential of PMN–xPT for piezoelectric and pyroelectric device applications.

压电微机械超声换能器(PMUT)在医疗阵列成像、手势识别、内窥成像、指纹识别等领域有着重要的应用, 而灵敏度等性能是影响其成像质量的主要因素。该文对基于PMN-PT圆形压电复合振动膜的压电微机械超声换能器等效电路模型进行分析, 并通过有限元法研究了压电层PMN-PT厚度对PMUT的发射电压响应、接收灵敏度的影响。仿真结果表明, 当压电层厚度为4.5 μm(厚度为基底厚度的90%)时, 换能器的发射电压响应级最大, 达到191.6 dB, 接收灵敏度级随厚度的增加基本呈线性上升趋势; 当压电层厚度为5.1 μm(厚度为基底厚度的102%)时, 回路增益(损耗)最大, 达到-64.50 dB。

折射率是光学晶体的基本参数，准确测定晶体的折射率能够为晶体的电光、声光、非线性应用提供基本计算参数和实验参量。为了准确测定Pb(Mg1/3Nb2/3)O3-PbTiO3(PMN-PT)晶体在可见光和近红外波段的折射率系数，搭建了激光自准直折射率测量系统，对纯铌酸锂晶体的折射率测试结果与现有文献报道误差小于1/1 000，使用该系统对沿<001>极化的Pb(Mg1/3Nb2/3)O3-0.39PbTiO3(PMN-0.39PT)单畴晶体进行了测定，得到了单畴的PMN-0.39PT晶体在波长分别为594 nm、633 nm、1 150 nm和1 520 nm时的折射率和色散方程，测量结果与现有文献规律性一致。结果表明该方法可用于准确快速测定新型电光晶体折射率。

Electromechanical and dielectric properties of PMN–PT ferroelectric ceramics are investigated. In particular, dielectric response studies focus on the investigation of the influence of the DC applied electric field on the dielectric permittivity as a function of temperature and frequency. Results reveal an electric field driven dielectric anomaly in the dielectric permittivity curves, 𝜀(E), which in turn prevails in the whole ferroelectric phase region and continuously vanishes for temperatures near the paraelectric-ferroelectric phase transition temperature. A schematic model for the domains dynamics of the studied material is proposed taking into account the simultaneous contribution of both 90∘ and 180∘ domains walls.Electromechanical and dielectric properties of PMN–PT ferroelectric ceramics are investigated. In particular, dielectric response studies focus on the investigation of the influence of the DC applied electric field on the dielectric permittivity as a function of temperature and frequency. Results reveal an electric field driven dielectric anomaly in the dielectric permittivity curves, 𝜀(E), which in turn prevails in the whole ferroelectric phase region and continuously vanishes for temperatures near the paraelectric-ferroelectric phase transition temperature. A schematic model for the domains dynamics of the studied material is proposed taking into account the simultaneous contribution of both 90∘ and 180∘ domains walls.

该文研究了Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3(PIN-PMN-PT)基片上声表面波(SAW)的传播特性。利用COMSOL软件建立SAW谐振器三维模型并进行模拟仿真。通过优化谐振器参数, 设计了一种具有超大机电耦合系数(K2)的谐振器结构。结果表明, 当欧拉角为(0°,-70°,0°)时, SH0模态的K2可优化到约85%, 且通带内无寄生响应。