Bi基微波介质材料结构-极化机理-介电性能关系研究

The present proposal aims at structure/property regulation in the Bi-based microwave dielectrics. The mechanism of polarization which is the decisive local factor for microwave dielectric properties will be studied by observing the relationship between microwave dielectric properties, coordination state and vibration mode of the crystal structure. The relations among structure, polarization and dielectric properties will be studied targeting at revealing the mechanism that how the structure controls the dielectric properties in the Bi-based microwave dielectrics. A series of Bi-based microwave dielectrics will be obtained and their structures will be tailored by ion-substitution or solid solution. The crystal structure details, including occupying, bond length, bond angle, cell parameters, degree of ordering etc., will be obtained by the Rietveld refinement using the synchrotron radiation X-ray diffraction data and the analysis of X-ray absorption fine structure (XAFS). The structure-dielectric properties curves would reveal the change law of microwave dielectric properties and crystal structure. Meanwhile, the mechanism of polarization will be studied by wide band dielectric spectrum combining with Raman and Infrared-THz spectra analysis, and the relationship between vibration mode and ion displacement polarization will be revealed, aiming at mastering the law of structure-polarization-dielectric property, and structure/property regulation in the Bi-based microwave dielectrics.

本项目以实现Bi基微波介质材料结构/性能调控为研究目标，以几种典型的Bi基微波介质材料为研究对象，探索决定其本征微波介电性能的极化机理，确立微波介电性能与离子配位环境以及振动模式之间的内在联系，从结构-极化机理-本征介电性能的角度揭示材料的结构对本征介电性能的作用机理。项目通过离子取代、固溶体的方式微调材料的结构，通过同步辐射XRD测试结合Rietveld精修，以及XAFS测试获得材料精确的结构信息，从而得到一系列结构、介电性能变化的数据，进而研究结构影响介电性能的规律；另一方面，本项目通过宽频介电谱测试研究Bi基微波介质材料的极化机理，结合晶格振动光谱学的相关理论以及Raman测试数据、远红外-THz光谱，解释结构中粒子的振动模式对介电性能的作用机制，最终掌握Bi基微波介质材料结构-极化-介电性能关系，实现Bi基微波介质材料结构/性能调控。

该项目自2016年立项以来，经过了三年的不懈努力，通过远红外反射谱及THz谱，研究了一系列Bi基白钨矿、褐钇铌矿、锆石相等微波介质陶瓷的本征极化机理，探索了铋基微波介质材料中相变机理及对介电性能的影响，确立了远红外振动模式、共价键、离子键与宏观介电性能的联系，依托快速发展的国家大科学装置，利用远红外线站机时400余小时，较为系统地研究了铋基微波介质材料的宽频段介电响应与精细结构；通过该项目的实施，在J Mater Chem C、J Am Ceram Soc等期刊上发表学术论文20篇，获批中国发明专利2项，培养了博士研究生1名，硕士研究生2名