New lead-free piezoelectric composites for high-power applications

适用于高功率应用的新型无铅压电复合材料

• 批准号: 414073759
• 负责人: Professor Dr. Jurij Koruza, Ph.D.
• 金额: --
• 依托单位: Institut für Chemische Technologie von Materialien
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/414073759?language=en
• 关键词: New; lead; free; piezoelectric; composites

Piezoelectric ceramics enable conversion between electrical and mechanical signals and are widely used in various electronic applications. High energy density and low power consumption make them indispensable in high-power applications, such as small voltage transformers and ultrasonic devices. Moreover, their miniaturization potential enables the development of new portable electronic devices and electronic body implants. High-power applications require piezoelectrically hard materials, whereby the hardening is conventionally achieved by pinning the ferroelectric domain walls with defect complexes. This hardening mechanism, however, suffers degradation of electromechanical properties at high vibration velocities and elevated temperatures, which considerably limits the output power and therefore represents a vital drawback for applications. Moreover, the state-of-the-art piezoelectrics contain large amounts of hazardous lead, placing them on the watch list of many environmental regulations. The main goal of the proposed project is to develop an alternative hardening mechanism, which will result in a new group of lead-free piezoceramics with higher and more stable high-power piezoelectric properties. Instead of using classical hardening with defect complexes, a new approach based on engineering the microstructure will be utilized. To this end, lead-free (3-0)-type piezoelectric composites will be designed using relaxor matrix and various rigid non-perovskite inclusions. It is hypothesized that in these composites the pinning of domain walls can be obtained by mechanical stresses and charged carriers from inclusions. To resolve the different mechanisms, composites with either semiconductive or insulating inclusions will be investigated. The pinning strength will be evaluated for small- and large-signal electromechanical excitation regimes over a broad frequency and temperature range. The high-power properties and depolarization behaviour will be compared to the state-of-the-art hard Pb(Zr,Ti)O3 materials. To understand the macroscopic electromechanical response, the project will additionally focus on simultaneous investigation of microstructural and crystallographic parameters. The crystallographic structure and residual stresses will be investigated using X-ray diffraction, nuclear magnetic resonance, and neutron diffraction. Moreover, in situ time-resolved measurements using high-energy X-ray diffraction will be utilized to determine the contributions from domain walls and lattice strains. Development of in situ high-power measurements will improve the general understanding of the non-linear behaviour of hard piezoelectrics. In summary, this project will introduce a new class of sustainable hard piezoelectric materials, provide basic scientific understanding of the novel hardening mechanism, and give guidelines for the design of other hard piezoelectrics utilizing the composite approach.

压电陶瓷能够实现电信号和机械信号之间的转换，并广泛用于各种电子应用。高能量密度和低功耗使其在高功率应用中不可或缺，例如小型电压互感器和超声波设备。此外，它们的小型化潜力使得能够开发新的便携式电子设备和电子身体植入物。高功率应用需要压电硬材料，由此常规地通过用缺陷复合物钉扎铁电畴壁来实现硬化。然而，这种硬化机制在高振动速度和升高的温度下遭受机电性能的退化，这大大限制了输出功率，因此代表了应用的重要缺点。此外，最先进的压电材料含有大量有害的铅，将其置于许多环境法规的观察名单上。该项目的主要目标是开发一种替代硬化机制，这将导致一组新的无铅压电陶瓷具有更高和更稳定的大功率压电性能。而不是使用经典的硬化与缺陷复合体，一个新的方法的基础上工程的微观结构将被利用。为此，无铅（3-0）型压电复合材料将设计使用弛豫矩阵和各种刚性非钙钛矿夹杂物。据推测，在这些复合材料中，畴壁的钉扎可以通过机械应力和夹杂物中的带电载流子来实现。为了解决不同的机制，复合材料与绝缘或绝缘夹杂物将进行研究。钉扎强度将在宽的频率和温度范围内的小信号和大信号机电激励制度进行评估。高功率性能和去极化行为将比较国家的最先进的硬Pb（Zr，Ti）O3材料。为了理解宏观机电响应，该项目还将重点关注微观结构和晶体学参数的同步研究。将使用X射线衍射、核磁共振和中子衍射研究晶体结构和残余应力。此外，使用高能X射线衍射的原位时间分辨测量将被用来确定畴壁和晶格应变的贡献。现场高功率测量的发展将提高对硬压电体非线性行为的普遍理解。总之，该项目将介绍一类新的可持续硬压电材料，提供对新硬化机制的基本科学理解，并为利用复合方法设计其他硬压电材料提供指导。