9504015 Phule Personal communication services (PCS) represent a burgeoning and revolutionary family of microwave based technologies (400 MHz to 30 GHz). Familiar examples include cellular telephones, wireless cable, direct broadcast, and interactive television. To store, transfer, and filter electromagnetic waves, components based on ceramic materials are indispensable. New and better ceramics for wireless communications (CWC), characterized by exceptionally high quality factors, a relatively high dielectric constant, and adequate temperature stability will be highly desirable for further miniaturization and enhanced performance of certain microwave components. The major goal of this program is to conduct a systematic investigation of the synthesis and processing of potentially novel ceramic materials for microwave applications. Our research is being conducted so as to gain deeper insights into the fundamental relationships between the atomic level defects, heterogeneous interfaces, and the microwave dielectric properties of ceramic materials. %%% For achieving the central goal of our research, it is critical to measure the dielectric properties of materials, in the microwave frequency range (400 MHz to 40 GHz). Using a microwave network analyzer is the only direct way to characterize such microwave properties. This award provides funds to acquire such a network analyzer. Presently, this unit is not available at the University of Pittsburgh. This instrument will enhance the quality of the research program. Using the network analyzer, we will be able to experimentally determine the microwave properties in relation to the composition and microstructure of sintered, polycrystalline ceramics in the tantalum oxide-zirconia, niobium oxidezirconia, and other systems. We plan to investigate the influence of composition, and micorstructural features (such as grain size, porosity, and grain boundary microchemistry) of samples processed using different sintering time-temperature profiles. We also seek to understand the influence of controlled levels of different dopants and impurities on the microwave dielectric constant and quality factor of different compositions. These properties will be measured at different temperatures (100- 500 K) so as to elucidate the fundamental mechanisms that influence microwave properties. ***
