Project Reports

[摘要] Dielectric polarization of a material under the magnetic field or an induced magnetization under the electric field requires the simultaneous presence of long-range ordering of magnetic moments and electric dipoles. Single phase materials suffer from the drawback that the magnetoelectric (ME) effect is considerably weak even at low temperatures, limiting their applicability in practical devices. Better alternatives are ME composites that have large magnitudes of the ME voltage coefficient. The composites exploit the product property of the materials. The ME effect can be realized using composites consisting of individual piezomagnetic and piezoelectric phases or individual magnetostrictive and piezoelectric phases. Magnetoelectric particulate composites consisting of piezoelectric and magnetostrictive materials with different connectivity schemes including “3-0” and “2-0”, and laminate bulk composite with “2-2” connectivity have been investigated. However, the understanding of the physical interaction occurring at the mesoscale interfaces between the magneto-elastic stresses and elasto-electric fields has not been achieved. The lack of this understanding has limited the ability to achieve the theoretical response of the material by coordinating the local electro-magnetic couplings, via coherent elastic interactions between phases. Comprehensive understanding of such interactions would enable the development of magnetoelectric materials exhibiting giant responses at small dimensions. This research program proposes to investigate the mesoscale physics in magnetoelectric materials, and to realize high magnetoelectric susceptibilities. The specific objectives of this program will be as following (i) investigation of the local magnetoelectric coefficient using magnetic force microscopy and piezo force microscopy; (ii) determine microstructure of the interfaces between magnetic and piezoelectric phases, using electron microscopies; (iii) find the correlation between local and bulk magnetoelectric responses, the interfacial microstructure for fine scale composites of various phase connectivities, and (iv) develop a 3D Phase Field model of spontaneously self-organizing nano-scale microstructures.

[发布日期] 2007-03-28

[学科分类] 材料科学（综合）

[关键词] ATOMIC FORCE MICROSCOPY;DIELECTRIC MATERIALS;DIMENSIONS;ELECTRIC DIPOLES;ELECTRIC FIELDS;ELECTRONS;MAGNETIC FIELDS;MAGNETIC MOMENTS;MAGNETIZATION;MICROSCOPY;MICROSTRUCTURE;PARTICULATES;PHYSICS;POLARIZATION;RESEARCH PROG