Controlling Microstructures and Interfaces in Oxide Thin Films via Electric Field Processing

磁电材料是一种外部磁场引起电响应或外部电场引起磁响应的材料。从历史上看，磁电行为很少有技术应用，因为在大多数表现出这种行为的材料中，响应太小。然而，当两种不同的材料--一种对电场敏感，另一种对磁场敏感--组合成复合材料时，磁电行为要强得多。该奖项支持基础研究，以了解这种复合磁电材料的行为，特别是两种材料之间的界面。除了了解这些材料中的界面外，还将研究一种新的制造方法，该方法通过施加电场来降低制造温度，从而减少界面层的混合，进一步提高磁电性能。这项研究的成果可以通过高灵敏度磁场检测、微波滤波器和先进逻辑器件等应用，造福美国经济、国防、安全和社会。这项研究涉及多个学科，包括制造，材料科学，复合材料，磁学和铁电性。多学科方法将有助于扩大代表性不足的群体在研究中的参与，并对工程教育产生积极影响。这项研究支持的研究重点是使用纳米压印光刻技术，以创造异质磁电薄膜复合材料的磁致伸缩和压电材料之间的独特的界面结构。基本假设是，功能行为是由界面应变耦合驱动的，因此控制界面是至关重要的。在这里，异质氧化物多层膜的制造是先进的理解和控制的各个阶段和界面的纳米结构性能的关系，同时通过电场处理。该研究涉及加工、结构特性和物理特性之间的显著相互作用和反馈。通过本研究，将加深对磁性、铁电和磁电材料的科学认识，包括：理解Ni、Zn、Co和Fe的化学计量比变化对镍铁氧体电磁和磁致伸缩性能的作用，理解电场处理过程中各相的结晶、致密化、晶粒生长和织构化;具有定制界面几何形状的异质多层的创建;通过常规烧结对共烧多层的理解;以及在共烧复合材料的电场处理期间理解和控制化学物质的相互扩散。

A magnetoelectric material is one for which an external magnetic field causes an electric response or an external electric field causes a magnetic response. Historically, magnetoelectric behavior has found few technological applications because the response was too small in most materials showing such behavior. When two different materials - one responsive to an electric field, and another responsive to magnetic field - are combined into a composite material, however, magnetoelectric behavior is much stronger. This award supports fundamental research to understand the behavior of such composite magnetoelectric materials, in particular the interfaces between the two materials. In addition to understanding the interfaces in these materials, a new manufacturing approach will be investigated, which reduces the manufacturing temperature by applying an electric field and thus reduces the mixing of layers across the interfaces, further improving magnetoelectric properties. The results from this research can benefit the U.S. economy, defense, security and society through applications such as highly sensitive magnetic field detection, microwave filters and advanced logic devices. This research involves several disciplines including manufacturing, materials science, composite materials, magnetics, and ferroelectricity. The multi-disciplinary approach will help broaden participation of underrepresented groups in research and positively impact engineering education. This research supports research focused on using nanoimprint lithography to create heterogeneous magnetoelectric thin film composites with unique interface structures between the magnetostrictive and piezoelectric materials. The underlying hypothesis is that the functional behavior is driven by interfacial strain coupling, and thus controlling the interface is critical. Here the manufacturing of heterogeneous oxide multilayers is advanced by understanding and controlling both the nanostructure-properties relationships of the individual phases and the interfaces simultaneously through electric field processing. The research involves significant interplay and feedback between processing, structural properties and physical properties. Through this research, the scientific knowledge of magnetic, ferroelectric and magnetoelectric materials will be advanced, including: an understanding of the role of stoichiometric variations of Ni, Zn, Co and Fe on electromagnetic and magnetostrictive properties of nickel ferrite; an understanding of crystallization, densification, grain growth and texturing of each phase separately via electric field processing; the creation of heterogeneous multilayers with a tailored interface geometry; an understanding of co-firing multilayers via conventional sintering; and understanding and controlling the interdiffusion of chemical species during electric field processing of co-fired composites.