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

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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.