Ferroics form an important sub-group of functional materials whose physical properties are sensitive to changes in electric and magnetic fields. A multiferroic is a material that exhibits two or more of the primary ferroic properties (ferromagnetism, ferroelectricity, ferroelasticity). A composite of ferromagnetic and ferroelectric materials will allow coupling between magnetic and electric subsystems that is mediated by mechanical forces and is a magneto-electric (ME) multiferroic. Such composites provide the opportunity for studies on the physics of ME coupling and have enormous potential for novel devices. This project will expand research on magneto-electric interactions to the new frontier of graded ferroics. Recent studies on compositionally graded ferromagnets and ferroelectrics have discovered new phenomena including internal potentials, induced anisotropy, and spontaneous strains. The planned efforts will involve the synthesis of functionally graded bilayers and multilayers of ferrites and ferroelectrics and studies on the effects of grading and the nature of ME interactions. The grading will involve piezomagnetic coupling in ferrites and piezoelectric coefficient in ferroelectrics and will be accomplished by grading the chemical composition. Studies on ME interactions will be done over 1 mHz ? 110 GHz including low-frequency effects and coupling at electromechanical, ferromagnetic and magnetoacoustic resonances. Postdoctoral research associates, graduate and undergraduate students and high school interns will participate in the research. Collaboration with industry is also planned for technology transfer.
This project is on composite materials that are capable of converting electrical energy to magnetic energy and have enormous potential for use in energy harvesting, energy storage and consumer electronics. The composite will have two components that respond individually to electric or magnetic field by producing a mechanical deformation. The project is aimed at tailoring properties of the two phases to accomplish improved mechanical response, and therefore, enhancement in the energy conversion efficiency. Changes in the chemical composition of each phase in a controlled manner are the avenue that will be explored to achieve these goals. Individual phases and composites with composition variations will be synthesized and characterized in terms of properties of importance for energy conversion. Postdoctoral research associates, graduate and undergraduate students and high school interns will participate in the research. Collaboration with industry is also planned for technology transfer.
This NSF supported project was on engineered composite materials that are capable of converting electrical energy to magnetic energy and have enormous potential for use in energy harvesting, information storage and consumer electronics. The composites have two components that respond individually to electric or magnetic field by producing a shape change. The project was aimed at tailoring properties of the two components to accomplish improved mechanical response, and therefore, enhancement in the field conversion efficiency. Changes in the magnetic and electrical properties of each phase in a controlled manner were the avenue that was explored to achieve these goals. Individual phases and composites with composition variations were synthesized and characterized in terms of properties of importance for field conversion (Figures 1 and 2). Significant scientific outcome include novel composites with order of magnitude enhancement in the field conversion efficiency (Fig.2) that are capable of measuring magnetic fields that are a billion times smaller than the Earth’s magnetic field (Fig.3). The efforts under this program resulted in 35 publications in peer reviewed journals and more than 50 presentations in national and international conferences. A total of 10 postdoctoral research associates, 4 graduate students and 8 undergraduate participated in the research and received training in advanced materials synthesis and characterization techniques. The program also contributed to collaboration with European scientists, visits by collaborators, and joint publications. Outreach activities included research internship for a total 13 high school students. The students submitted reports based on their research findings to the Siemens Competition and Intel Science and Technology Competition. Four students were regional finalists in the Siemens Competition. The composites developed under this program have enormous potential for use in consumer electronics (cell phones, information storage), Homeland security (whole-body scanners) and the National Defense (components for radars, detection of improvised explosive devices). Our composite based magnetic sensors are of interest for early warning systems for earthquakes and imaging of cardiac and neural magnetic fields.
