New Ordered Perovskite Dielectrics For Microwave Applications

氧化物钙钛矿（ABO3）具有在微波区维持出色介电响应的能力，并可容纳广泛的化学取代，是研究最广泛和技术最重要的微波介电材料家族。 对于混合金属钙钛矿，其中结构中的A或B（或两者）位置包含不同阳离子的混合物，已经清楚地建立了高品质因子（低介电损耗）与改进的阳离子顺序之间的相关性。 然而，只有有限的子集有序钙钛矿形成化学计量已被检查，和许多新的系统仍有待探索。 该提案使用基于“非整数”价A位化学的新方法来稳定几个全新的B位有序钙钛矿家族，其适合于在微波通信中用作低损耗的介电常数。 许多新材料在低温下表现出低熔点和高反应性，这也使它们在低温共烧陶瓷（LTCC）技术中具有潜在的应用价值。陶瓷微波介质氧化物独特的电学性能通过减小谐振器、滤波器、微波通信器件的尺寸和成本，以及从蜂窝电话到全球定位技术的系统中的振荡器。 虽然现有的材料足以满足当前的应用，但下一代系统需要具有增强的介电响应的新材料。 该提案中的研究旨在通过使用新的设计策略来识别这些材料，以制备基于钙钛矿结构的新系列陶瓷微波炉。

With their ability to sustain an outstanding dielectric response in the microwave region and accommodate extensive chemical substitution, oxide perovskites (ABO3) are the most widely studied and technologicallyimportant family of microwave dielectrics. For mixed-metal perovskites, where the A or B (or both) positions in the structure contain mixtures of different cations, a correlation between a high quality factor (low dielectric loss) and improved cation order has been clearly established. However, only a limited sub-set of ordered perovskite-forming stoichiometries has been examined, and many new systems are still to be explored. This proposal uses new approaches based on "non-integer" valence A-site chemistries to stabilize several completely new families of B-site ordered perovskites suitable for application as low-loss dielectrics in microwave communications. Many of the new materials lie in systems known to exhibit low melting points and high reactivity at low temperature, which also make them potentially useful for applications in low temperature co-fired ceramic (LTCC) technology.The unique electrical properties of ceramic microwave dielectric oxides have revolutionized microwave-based communications by reducing the size and cost of resonators, filters, and oscillators in systems ranging from cellular telephones to global positioning technologies. Although the existing materials are adequate for current applications the next generation of systems requires new materials with an enhanced dielectric response. The research in this proposal is aimed toward identifying these materials by using a novel design strategy to prepare new families of ceramic microwave dielectrics based on the perovskite structure.