Nanostructural Evolution and Magnetic Response in the Oxidation of FeCo Nanomaterials

技术：S计划对磁性纳米颗粒的合成、结构、性能和性能关系进行研究，该纳米颗粒有望在射频吸收、医学、射频加热和具有独特磁机械响应的铁氧体等领域得到应用。这项工作的学术价值在于：(1)加深了对FeCo/铁氧体纳米复合材料的纳米结构演变、氧化产物和氧化速率的理解；(2)纳米结构(包括表面和界面结晶学、金属和氧化物体积分数、小颗粒热力学和组成)与MNPs、磁流体和复合材料的高频开关的关系。研究目标是在以下方面加深对磁性金属/氧化物核壳结构的基本了解：(A)了解氧化物形成的顺序和多面体磁性FeCo纳米颗粒的外延关系；(B)模拟氧化过程中发生的化学分配及其在MNPs表面和界面各向异性形成中的作用？S在MNPs中的表面和界面各向异性的形成；(C)微观结构观察和磁性能测量，以确定控制Neel驰豫过程的各向异性机制；以及(D)Neel驰豫在两相FeCo/铁氧体MNPs的射频加热中的作用。这项工作与匹兹堡希尔曼癌症研究中心合作开发用于热消融癌症治疗的纳米颗粒的射频加热，并与匹兹堡麦高恩组织工程中心合作开发组织支架的磁性标记和铁凝胶磁机械响应。非技术性：潜在的广泛影响在于这些材料在流体、聚合物和环氧体的射频加热方面有希望。这项工作将进一步了解纳米结构在这些应用中的发展和磁热响应的控制。纳米颗粒的高效点源加热可用于热消融癌症治疗和促进组织支架的附着，前提是可以设计生物相容的粘附性氧化壳，并用适当的表面活性剂使其功能化，以稳定水中的磁流体和抗体，以促进细胞或组织的附着。工作将在MMM和材料会议(MRS和/或TMS)的出版物和演示文稿中传播。互动和协作也将有助于广泛传播。我们将与NRIM的K.Hono对场离子显微镜和Duqune大学的Monica Soresu进行互动。用于穆斯堡尔谱学。研究将与教育倡议相结合。2007年，皮？S开设了一门本科(UG)课程：磁性材料的结构、性能和性能关系？在教授了十年的研究生课程？应用磁学和磁性材料？CMU材料科学与工程(MSE)系。派？S开发了Powerpoint模块(2007年)，并通过CMU黑板系统分发了350页的章节。这些将被扩展，目的是出版UG磁性纳米材料文本。在这个项目期间，皮？S将继续赞助UG研究项目(有许多女性和少数民族学生)的悠久历史。

TECHNICAL: PI?s plan to conduct research on synthesis, structure, properties and performance relationships in magnetic nanoparticles (MNPs) having promise for applications in RF absorption, medicine, RF heating and ferrogels with unique magnetomechanical response. The intellectual merit of the work lies in: (1) furthering understanding of nanostructural evolution, oxidation products and rates of FeCo/ferrite nanocomposite materials and (2) the relationship of nanostructure (including surface and interface crystallography, metal and oxide volume fractions, thermodynamics of small particles and composition) with high frequency switching of MNPs, ferrofluids and composites. Research objectives are to develop fundamental understanding of magnetic metal/oxide core shell structures in terms of: (a) understanding the sequence of oxide formation and epitaxial relationships with polyhedral facetted magnetic FeCo nanoparticles; (b) modeling chemical partitioning occurring in oxidation and it?s role in developing surface and interfacial anisotropy in MNPs; (c) microstructural observations and magnetic properties measurements to determine anisotropy mechanisms which control Neel relaxation processes and (d) the role of Neel relaxation in the RF field activated heating of 2-phase FeCo/ferrite MNPs. This work couples with collaborations with the Pittsburgh Hillman Cancer Research Center to develop RF heating of nanoparticles for thermoablative cancer therapy and the Pittsburgh McGowan Tissue Engineering Center to develop magnetic tagging of tissue scaffolds and ferrogel magnetomechanical response for the same. NON-TECHNICAL: The potential for broad impact lies in the materials having promise in RF heating of fluids, polymers and epoxies. The work will further understanding of nanostructural development and control of magnetothermal response in these applications. Efficient point source heating of nanoparticles can be exploited for thermoablative cancer therapies and to promote attachment to tissue scaffolds if adherent, biocompatible oxide shells can be engineered and functionalized with appropriate surfactants to stabilize aqueous ferrofluids and antibodies to promote cell or tissue attachment. Work will be disseminated in publications and presentations at the MMM and materials conferences (MRS and/or TMS). Interactions and collaborations will also aid broad dissemination. We will interact with K. Hono of NRIM for field ion microscopy and Monica Sorescu of Duquesne Univ. for Mossbauer spectroscopy. Research will couple to educational initiatives. The PI?s have offered (2007) an undergraduate (UG) course ?Structure, Properties and Performance Relationships in Magnetic Materials? following a decade teaching the graduate course ?Applied Magnetism and Magnetic Materials? in the CMU Materials Science and Engineering (MSE) Dept. The PI?s have developed Powerpoint modules (2007) and distributed 350 pages of chapters through the CMU Blackboard system. These will be extended with the aim of publishing an UG Magnetic Nanomaterials text. The PI?s will continue a long history of sponsoring UG research projects (with many women and minority students), during this project.