Quenching enhanced lattice polarizability in lead-free ferroelectrics

淬火增强无铅铁电体的晶格极化率

• 批准号: 414311761
• 负责人: Professor Dr. Hans-Joachim Kleebe, since 1/2022
• 金额: --
• 依托单位: Institut für Angewandte Geowissenschaften (IAG)
• 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 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/414311761?language=en
• 关键词: Quenching; enhanced; lattice; polarizability; lead

Piezoelectric materials constitute about 25% of the world’s market of electroceramics and is expected to grow further due to their potential for miniaturization. While majority of these applications employ the perovskite Pb(Zr,Ti)O3 (PZT), steps are being taken to replace it with lead-free alternatives due to escalating concerns of toxicity and environmental damage. Extensive research on lead-free ferroelectrics in the past two decades has resulted in a general consensus that, there is no single class of lead-free material that can replace the versatile PZT. In the phasing out of lead-based ferroelectrics, the lead-free materials are foreseen to replace PZT, firstly in high power ultrasonic applications that demand relatively lower stringent requirements. Of the several lead-free classes of materials, bismuth (Bi) based materials offer significant advantages. The (1-x)Na1/2Bi1/2TiO3-xBaTiO3 (NBT-BT) compositions are beneficial due to their exceptionally good high power characteristics, in comparison to PZT. BiFeO3 (BF) with Bi3+ exhibiting lone-pair effect similar to Pb2+, is another promising material foreseen to replace PZT for high temperature applications, in future. Yet, these materials have to be fine-tuned to suit specific conditions under device operation.It was recently demonstrated that quenching enhances the thermal stability and ferroelectric properties of Bi based ferroelectrics. In this project, the role of quenching Bi-based materials will be investigated to (a) optimize the quenching conditions to evade microcracking and obtain desired material properties, (b) understand the structural origin of the enhanced lattice distortion, which is attributed to the increased thermal stability and improved ferroelectric properties and (c) establish quenching as an alternate processing route to tailor material properties of functional materials. This will be achieved by studying the representative relaxor NBT-BT and ferroelectric BF-BT compositions. The preliminary work discussed in the proposal provides the basis for optimizing the quenching conditions, which combined with electrical and mechanical property measurements will establish the processing routes. The average (synchrotron diffraction) and local (pair-distribution function analysis and transmission electron microscopy) structural analysis will probe the details of cation ordering, Bi3+ off-centering and quenching induced phase shifts. In the specific case of relaxors, quenching induced ferroelectric order will be investigated from the detailed characterization and quantification of polar nano regions. The comprehensive structure-microstructure-processing-property correlation established from this study is expected to promote quenching as a generic tool to tailor properties of functional materials.

压电材料约占世界电子市场市场的25％，由于其微型化的潜力，预计将进一步增长。尽管这些应用中的大多数采用了钙钛矿PB（ZR，TI）O3（PZT），但由于对毒性和环境损害的担忧升级，正在采取步骤用无铅替代方案代替它。在过去的二十年中，对无铅铁电的广泛研究导致了一般共识，即没有一类无铅材料可以替代多功能PZT。在基于铅的铁电基质的逐步缩进中，可以预见到的无铅材料可以替换PZT，首先是在高功率超声应用中，要求相对较低的严格要求。在几种无铅类的材料类别中，基于二晶木（BI）的材料具有显着优势。与PZT相比，（1-X）Na1/2bi1/2tio3-XBATIO3（NBT-BT）组成由于其异常良好的高功率特征而是有益的。 Bififo3（BF）带有BI3+表现出类似于PB2+的休息效果，这是另一种预见的材料，预计将来可以替代高温应用的PZT。然而，这些材料必须进行微调以适合设备操作下的特定条件。最近，淬火增强了基于BI的铁电气的热稳定性和铁电特性。在该项目中，将研究淬灭BI基材料的作用，以（a）优化避开微裂纹并获得所需的材料特性的淬火条件，（b）了解增强的晶格失真的结构起源，这归因于增强的热稳定性和提高的材料材料的Quince protiont ofterational offerational tailor的材料，以替代材料的材料来替代材料。这将通过研究代表性的松弛剂NBT-BT和铁电BF-BT组成来实现。提案中讨论的初步工作为优化淬火条件提供了基础，结合电气和机械性能测量将建立处理路线。平均（同步加速器衍射）和局部（配对分布函数分析和传输电子显微镜）结构分析将探测阳离子顺序，BI3+偏置和淬火诱导的相移的细节。在放松剂的特定情况下，将从极性纳米区域的详细表征和数量中研究淬灭诱导的铁电顺序。根据这项研究建立的综合结构微观结构 - 加工性 - 加工相关性将促进淬灭，作为量身定制功能材料特性的通用工具。