Magnetostrictive-Piezoelectric Nanocomposites with Unusual Magnetoelectric Properties

技术：多铁性材料同时具有两种或两种以上的有序结构，它们同时具有电场和磁场的耦合，但单相多铁材料的磁电耦合系数极小，使得其实际应用几乎是不可能的。由磁致伸缩和压电相组成的多铁性复合材料比单相材料具有更大的磁致伸缩系数，但复合材料的微观结构难以控制，严重制约了其发展。在这个项目中，PI将使用基于纳米光刻的新方法来开发磁致伸缩-压电纳米复合材料(MPNC)，该方法允许人们在磁致伸缩或压电基质中精确地设计纳米级填料的尺寸、形态和分布。这种纳米结构工程将使PI能够设计和优化具有不同寻常的材料对称性和显著增强的ME耦合的MPNC。研究的三个目标是：(1)利用纳米压印光刻(NIL)和软光刻(SL)开发新颖的纳米复合材料加工技术，以精确控制磁致伸缩或压电基质中第二相纳米薄膜的尺寸、形貌和分布；将使用NIL或SL对基质进行图案化，然后将其用作模板以沉积具有设计尺寸、形态和分布的第二相填料；将使用这些技术加工三维纳米结构复合材料，重点是基于TbDyFe合金、PVDF聚合物和PZT陶瓷的材料；(2)在PI的理论建模和基于能量最小化和均匀化理论的模拟的指导下，通过优化设计的填料尺寸、形貌和分布来制备具有特殊材料对称性和显著提高ME性能的MPNC；(3)在多个长度尺度上表征MPNC的微观结构现象和ME特性，并验证理论建模和模拟。非技术性：教育和推广活动与研究紧密结合在一起，包括在综合研究和教育计划中培训研究生；每年通过华盛顿大学本科生研究计划培训本科生；以及为K-12教师和学生设计一套简单的纳米压印实验，以传达纳米技术的关键概念。支持纳米光刻的复合加工可能导致具有优化功能的纳米结构设计的设备和系统。综合研究、教育和推广计划将激发K-12和大学生的科学兴趣，促进公众对纳米技术的了解，并吸引和培养纳米技术这一战略重要领域的下一代劳动力。

TECHNICAL: Multiferroic materials possess two or more types of orders simultaneouslythat couple the electric and magnetic fields, yet the magnetoelectric (ME) coupling coefficients in single phase multiferroics are extremely small, making their practical applications virtually impossible. Large efforts have been devoted to developing multiferroic composites consisting of magnetostrictive and piezoelectric phases, which could possess much larger ME coefficients than single-phase materials, yet the difficulty in controlling the microstructures of the composites severely limited their development. In this project PI will develop magnetostrictive-piezoelectric nanocomposites (MPNC) using novel nanolithography based approaches, which allows one to engineer the size, morphology, and distribution of nanoscale fillers precisely in a magnetostrictive or piezoelectric matrix. Such nanostructure engineering will enable PI to design and optimize MPNC with unusual material symmetries and dramatically enhanced ME coupling. The three research goals are to: (1) Develop novel nanocomposite processing techniques using nanoimprint lithography (NIL) and soft lithography (SL) to precisely control the size, morphology, and distributions of second-phase nanofillers in a magnetostrictive or piezoelectric matrix; the matrix will be patterned using NIL or SL, which is then used as a template to deposit second-phase fillers with designed size, morphology, and distribution; three-dimensional nanostructured composites will be processed using these techniques, focusing on materials based on TbDyFe alloys, PVDF polymers, and PZT ceramics; (2) Process MPNC with optimally designed fillers size, morphology, and distribution for unusual material symmetries and dramatically enhanced ME properties, guided by PI's theoretical modeling and simulations using energy minimization approach and homogenization theory; and (3) Characterize the microstructural phenomena and ME properties of MPNC at multiple length scales, and validate theoretical modeling and simulations. NON-TECHNICAL: The education and outreach activities are tightly integrated into research, including training graduate student in an integrated research and educational program; training undergraduate student each year through Undergraduate Research Program at University of Washington; and design a set of simple experiments underlying nanoimprinting for K-12 teachers and students to convey the key concepts of nanotechnology. Nanolithography-enabled composite processing could lead to nanostructure-designed devices and systems with optimized functionality. The integrated research, education and outreach program will stimulate scientific interests of K-12 and college students, promote public understanding on nanotechnology, and attract and train next generation of work force in the strategic important field of nanotechnology.