铌酸钾钠基无铅压电材料的缺陷化学

The research of lead-free piezoelectric ceramics has attracted much attention because of the sustainable development of human society and the implementation of regulations about lead-free electronic products. Potassium sodium niobate is considered as a leading lead-free candidate with high Curie temperature and good piezoelectric properties. On the basis of comprehensive literature study and preliminary research of KNN based lead-free piezoelectric ceramics, the proposed research include: (1) intrinsic defect chemistry of the KNN based materials and substitute mechanism of several typical ions; (2) the effect the type/amount of doping ions, preparation and aging process on the formation complex defects in the KNN materials; (3) the effects of the interaction between complex defects and domains on the electrical properties such as dielectric, ferroelectric, piezoelectric properties and electric field induced strain; (4) the effect point defects on the time and temperature stability of domain orientation in the poled KNN-based ceramics with various doping. It is anticipated that the proposed work will lead to getting a Brouwer diagram of the KNN materials, determining substitute mechanism of several typical ions, finding the method of regulation of KNN-based ceramic complex defect formation, uncovering the relationship between the complex defects and the electrical properties. These results provided reference for choice of doping and sintering aids in KNN-based lead-free piezoelectric ceramics.

人类社会可持续发展的需要和电子产品无铅化法规的全面实施，使无铅压电陶瓷的研发受到了极大的关注。铌酸钾钠（KNN）由于具有高的居里温度和优异的压电性能被认为是重要的无铅压电候选材料。本申请项目在全面调研KNN基陶瓷研究进展及前期预研的基础上，提出以研究KNN基材料的本征缺陷化学为基础，系统研究几种典型离子的取代特性；研究掺杂离子类型、掺杂量、制备工艺和老化工艺对KNN材料中缔合缺陷形成的影响；研究缔合缺陷与电畴的相互作用对材料介电、铁电、压电及电致应变等性能的影响规律；研究各种掺杂KNN基陶瓷极化后电畴的时间稳定性和温度稳定性，对比研究得到点缺陷对电畴取向稳定性的影响。项目的成功实施，预期会得到KNN材料的Brouwer图，确定几种典型掺杂离子的取代特性，找到调控KNN基陶瓷缔合缺陷形成的方法，揭示缔合缺陷和电性能的相互关系，为铌酸钾钠基无铅压电陶瓷的掺杂改性和烧结助剂的选择提供依据。

铌酸钾钠（KNN）是一类重要的无铅压电材料，本项目围绕KNN中点缺陷的形成、调控及其对电性能的影响开展研究工作，获得了如下成果：. （1）提出了一种简单高效筛选KNN基陶瓷烧结助剂的方法，该方法对其它氧化物陶瓷材料烧结助剂的筛选也同样适用；. （2）筛选出了GeO2和硼砂两种KNN的新烧结助剂，并详细研究了两种烧结助剂对KNN基陶瓷烧结和电性能的影响；. （3）KNN的受主掺杂有三个明显的效果，包括改善KNN陶瓷粉末的合成、降低KNN陶瓷的烧结温度，受主离子和氧空位形成缺陷偶极子对KNN陶瓷改性；. （4）相比于三价和四价受主离子，二价离子，特别是二价铜离子，对KNN材料的机械品质因数有明显的提高，这归因于缔合缺陷的类型和浓度的不同；. （5）研究了Cu2+掺杂KNN基陶瓷的电致应变，发现Cu2+掺杂可以明显增大KNN基陶瓷的电致应变，提出可以用缺陷偶极子和自发偶极子的协同作用机制来解释。. （6）发表了12篇SCI收录论文。