New Non-centrosymmetric Oxides with Piezoelectric and Ferroelectric Properies

该项目旨在合成和表征一系列新的氧化物化合物，包括六方钨青铜和Aurivillius相。这两类氧化物将是非中心对称(NCS)和极性的，允许压电和铁电行为。除了结构表征、粉末和单晶X射线衍射和中子衍射外，还将通过逆压电滞回和铁电滞后(极化与电场)测量来表征材料。所有的测量都将使我们能够确定物理反应的结构起源。从这项研究中获得的知识将有助于发展结构和性质之间的关系，并最终使新材料类别的“合理”设计成为可能。技术进步的基础是新材料类别的创造，即合成。理想情况下，这些新材料应该具有特定的技术特性。已经开发出一种合成策略，旨在创造具有特定性质的压电性和铁电性的新材料。压电体和铁电体都被用于许多应用中，例如非易失性随机存取存储器、电容器、传感器和致动器。然而，研究从根本上新型的压电和铁电材料是具有挑战性的。这归因于所讨论材料的严格对称性要求，必须实现非中心对称(NCS)晶体结构。目前的合成策略现在可以将NCS在任何新材料中的发生率增加到近40%-远远高于在自然界中观察到的15%。这些合成策略正在导致具有可预测性能的新材料，从而使“理性”材料设计范例的发展成为可能。

This project aims to synthesize and structurally characterize a series of new oxide compounds to include hexagonal tungsten bronzes and Aurivillius phases. These two families of oxides will be non-centrosymmetric (NCS) and polar, allowing for piezoelectric and ferroelectric behavior. In addition to structural characterization, powder and single crystal X-ray diffraction and neutron diffraction, the materials will be characterized by converse piezoelectric and ferroelectric hysteresis (polarization vs. electric field) measurements. All of the measurements will allow us to determine the structural origin of the physical response. The knowledge gained from this research will aid in developing structure property relationships, and ultimately enable the 'rational' design of new classes of materials.%%%Fundamental to advances in technology is the creation, i.e. synthesis, of new classes of materials. Ideally, these new materials should be tailored with specific technological properties. A synthetic strategy has been developed that aims to create new materials with specific properties piezoelectricity and ferroelectricity. Both piezoelectrics and ferroelectrics are used in a host of applications, such as non-volatile random access memories, capacitors, sensors, and actuators. Research, however, into fundamentally new piezoelectric and ferroelectric materials is challenging. This is attributable to the strict symmetry requirements of the materials in question a non-centrosymmetric (NCS) crystal structure must be achieved. Current synthetic strategies can now increase the incidence of NCS, in any new material, to nearly 40% - far greater than the 15% observed in nature. These synthetic strategies are leading to new materials with predictable properties, and are therefore enabling the development of a 'rational' materials design paradigm.