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

点击翻译按钮获取中文摘要

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.