An ultrahigh-frequencey and high-field complex impedance spectrometer for the studies of nanopolar and amorphous dielectric materials

当今社会的发展在很大程度上是基于无机功能材料的使用，这些材料表现出优异的电、磁、光等性能。铁电材料是一类重要的功能材料。它们在半导体工业中被用作高度集成的电容和非易失性动态随机存取存储器。它们也被探索作为所谓的“智能”材料，能够通过机电传导过程感知和响应环境变化（驱动），例如有效控制汽车的振动或直升机的噪音。这些应用得益于铁电材料优异的晶体物理特性，其特点是具有极高的介电常数和可电切换的自发极化（偶极矩）。因此，结构-性质关系对铁电材料的评价是至关重要的，而铁电材料尚未得到彻底的理解。本提案所要求的复杂介电光谱仪将为这一目的提供一个强有力的工具。本研究计划是为了系统地研究一类铁电材料及其相关材料的介电特性而提出的。在广泛的频率范围内，包括射频范围、温度范围和高电场范围内，测量和分析材料对外部交流激励场的复杂介电响应。在这种特殊条件下的研究将使我们更好地理解偶极弛豫的性质和动力学、结构相变和宏观性质。微观结构和宏观性能关系的建立将反过来指导设计和合成性能更强的新型铁电材料和相关材料，以实现先进的应用。因此，它既具有根本意义又具有实际重要性。所需要的设备是实施本研究计划不可缺少的。

The development of today's society is based to a large extent on the use of inorganic functional materials that exhibit outstanding electric, magnetic, optical and other properties. Ferroelectric materials constitute an important class of functional materials. They are being used in the semiconductor industries as highly integrated capacitance and non-volatile dynamic random access memories. They are also being explored as the so-call 'smart' materials capable of sensing and responding to the environment changes (actuating) through an electro-mechanical tranduction process, for instance to effectively control the vibrations of cars or the noises of helicopters. These applications benefit from the outstanding crystal physical properties of the ferroelectric materials, which are characterized by an extremely high dielectric constant and an electrically switchable spontaneous polarization (dipolar moments). Therefore, the structure-property relations are central to an appreciation of ferroelectric materials, which have not been understood thoroughly. The complex dielectric spectrometer requested in this proposal will provide a powerful tool for such purpose. This research program is proposed to systematically study the dielectric properties of a large class of ferroelectric and related materials by means of the Dielectric and Impedance Spectroscopy. The complex dielectric response of the materials to an external AC exciting field will be measured and analyzed in a wide range of frequency up to radio frequecy range, temperature and high electric field. The investigations under such unique conditions will allow us to provide a better understanding of the nature and dynamics of dipolar relaxation, the structural phase transitions and the macroscopic properties. The establishment of the micro-structure and macro-property relations will in turn guide the design and synthesis of new ferroelectric and related materials with more enhanced properties for advanced applications. It is therefore of both fundamental relevance and practical importance. And the equipment requested is indispensable for the implementation of this research program.