Preparation of Advanced Nanomaterials from Single Source Designer Precursors

有了这个奖项，大分子、超分子和纳米化学项目将资助莱斯大学的Kenton H. Whitmire的研究，以开发制造具有潜在有用磁性的高级金属物质的新方法。这项工作的重点是由铁或锰等金属制成的材料。当这些金属与磷等物质结合时，两者可以以许多不同的形式结合在一起。例如，铁与磷结合至少可以以五种方式形成。所有这些产生的物质都是不同的，但它们都是半导体，其中一些表现出不寻常的行为。其中一种被称为“磁热”。这意味着它们的磁性状态随温度变化。这样的物质可以用来制造电子冰箱，换句话说，一种不需要使用制冷剂气体的固态设备。因此，这项工作具有广泛的影响：对新的和潜在的重要材料的生产，这些材料将在工业中找到各种各样的用途，并通过培训下一代科学家掌握制备专门材料的先进技术。这项研究正在开发新的方法来制备传统方法难以或不可能合成的先进材料。为了实现这一目标，正在制备一种或多种过渡金属(M)与15族元素(E)结合的新分子前体。所得的E-M组合物具有重要的磁性、电子性和/或超导性。本项目旨在克服制备二元、三元及更高过渡金属/主族元素组成的先进材料的合成挑战。该方法考虑基于含有一种或多种过渡金属以及磷和/或砷的过渡金属羰基化合物的单一来源前体。使用复杂的有机金属技术制备分子前体，以获得所需的E/M组合物。这些化合物通过多种方法进行表征，包括单晶x射线衍射、多核和变温核磁共振波谱、红外波谱和质谱等。这些前体转化为所需的材料是通过热分解方法来检验的。通过扫描电子显微镜、透射电子显微镜、x射线光电子能谱、粉末和薄膜x射线衍射、能量色散x射线能谱以及其他电子和磁测量技术对制备的纳米颗粒或薄膜材料进行分析。

With this award, the Macromolecular, Supramolecular and Nanochemistry program is funding the research of Kenton H. Whitmire of Rice University to develop new ways to make advanced metallic substances with potentially useful magnetic properties. The work is focusing on materials made from metals such as iron or manganese. When these metals are combined with a substance such as phosphorus, the two can come together in many different forms. Iron combined with phosphorus, for example, can form in at least five ways. All of these resulting substances are different, but they all are semiconductors, some of which display unusual behavior. One of these is called "magnetocaloric". This means their magnetic state varies with temperature. Substances like this could be used to produce an electronic refrigerator, in other words, a solid-state device that does not require the use of refrigerant gases. This work is, thus, having a broad impact: on the production of new and potentially important materials that will find a wide variety of uses in industry, and through the training of the next generation of scientists in advanced techniques for preparing specialized materials.This research is developing new ways to prepare advanced materials that are difficult or impossible to synthesize by conventional means. In order to achieve this goal, new molecular precursors combining one or more transition metals (M) with the group 15 elements (E) are being prepared. The resulting E-M compositions have important magnetic, electronic and/or superconducting properties. This project is geared to overcoming the synthetic challenges of preparing advanced materials of binary, ternary and higher transition metal/main group element compositions. The approach considers single source precursors based on transition metal carbonyl compounds containing one or more transition metals as well as phosphorus and/or arsenic. The molecular precursors are prepared using sophisticated organometallic techniques to achieve the desired E/M compositions. These compounds are characterized by a variety of methods including single crystal X-ray diffraction, multinuclear and variable temperature nuclear magnetic resonance spectroscopy, infrared spectroscopy and mass spectrometry among others. The conversion of these precursors to the desired materials is examined by thermal decomposition methods. The resulting materials, prepared either as nanoparticles or thin films, are analyzed by scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, powder and film X-ray diffraction, energy dispersive X-ray spectroscopy, and other electronic and magnetic measurement techniques.