Mixed metal melts as solvents for materials synthesis

混合金属熔体作为材料合成的溶剂

• 批准号: 1106150
• 负责人: Susan Latturner
• 金额: $ 39万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-15 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1106150&HistoricalAwards=false
• 关键词: Mixed; metal; melts; solvents; materials

TECHNICAL SUMMARY:This research is supported by the Solid State and Materials Chemistry program of the NSF Division of Materials Research. This project will investigate the synthesis of new intermetallics, Zintl phases, and complex salts from metal fluxes comprised of two elements. Synthesis in metal flux allows reactions to take place in a molten solution; this liquid state method enables crystal growth and the formation of unusual new metastable phases. Combining two different metals to act as a mixed solvent allows for lower reaction temperatures due to eutectic formation, and improved solubility of a wider range of reactants. Two areas will be explored: the synthesis of magnetic intermetallic phases in lanthanide/transition metal (Ln/T) eutectic fluxes, and the synthesis of lightweight Zintl phases and complex salt-like compounds in alkaline earth-rich (AE) flux mixtures. The Ln/T flux syntheses will yield new compounds with complex crystal structures and magnetic properties stemming from magnetic moments of both the lanthanide and the transition metal element. Possible magnetic behavior that may arise includes magnetic ordering, spin glass behavior, superconductivity, magnetoresistive behavior, mixed valence and heavy fermion behavior. Reactions in alkaline earth rich fluxes will produce a wide range of classes of materials, depending on the flux metals used. Fluxes rich in highly electropositive Ca, Sr, or Ba will strongly reduce main group elements to form new Zintl phases and complex salts. These include new complex hydride phases which may be of interest for hydrogen storage. Using Mg-rich fluxes will yield more borderline products which do not exhibit complete charge transfer and may as a result show metal-to-insulator transitions. NON-TECHNICAL SUMMARY:The Solid State and Materials Chemistry program of the NSF Division of Materials Research supports exploration of unusual synthetic methods which may lead to discovery of new compounds with useful properties. The metal flux technique uses molten metals as solvents for synthesis and crystal growth of alloys and intermetallics. Magnetic compounds are being sought by carrying out reactions of a variety of elements in flux mixtures of two magnetic metals (a lanthanide metal and a transition metal). Light weight alloys for hydrogen storage and potential aerospace applications are being sought from reactions of elements in flux mixtures comprised of lightweight metals such as Li, Mg, and Ca. Flux growth often yields products in the form of large crystals; this allows for use of a large suite of characterization techniques which will lead to a better understanding of how magnetic and electronic properties are derived from the structure and composition of the compounds. This research will educate undergraduate, graduate and postdoctoral researchers in materials chemistry, which will strengthen the developing program in materials science at Florida State University. This highly interdisciplinary project involves collaboration with scientists in a variety of areas (such as chemistry, physics, and engineering); this will allow the participants to understand the increasingly complex nature of modern science.

技术摘要：这项研究得到了美国国家科学基金会材料研究部的固态和材料化学项目的支持。 该项目将研究从由两种元素组成的金属熔剂中合成新型金属间化合物、Zintl 相和复合盐。 金属熔剂中的合成允许反应在熔融溶液中发生；这种液态方法能够实现晶体生长并形成不寻常的新亚稳态相。 将两种不同的金属结合起来作为混合溶剂，由于形成共晶，可以降低反应温度，并提高更广泛反应物的溶解度。 将探索两个领域：在镧系元素/过渡金属（Ln/T）共晶熔剂中合成磁性金属间相，以及在富含碱土金属（AE）熔剂混合物中合成轻质Zintl相和复杂的盐状化合物。 Ln/T 通量合成将产生具有复杂晶体结构和源自镧系元素和过渡金属元素磁矩的磁性的新化合物。 可能出现的磁行为包括磁有序、自旋玻璃行为、超导性、磁阻行为、混合价态和重费米子行为。 富含碱土金属的助熔剂中的反应将产生多种类型的材料，具体取决于所使用的助熔剂金属。 富含高正电性 Ca、Sr 或 Ba 的助熔剂会强烈还原主族元素，形成新的 Zintl 相和复合盐。 其中包括新的复杂氢化物相，可能对储氢感兴趣。 使用富含镁的助焊剂将产生更多的边缘产物，这些产物不表现出完全的电荷转移，并且可能因此表现出金属到绝缘体的转变。非技术摘要：美国国家科学基金会材料研究部的固态和材料化学项目支持探索不寻常的合成方法，这可能会导致发现具有有用特性的新化合物。 金属熔剂技术使用熔融金属作为合金和金属间化合物的合成和晶体生长的溶剂。 人们正在通过在两种磁性金属（一种镧系金属和一种过渡金属）的助熔剂混合物中进行多种元素的反应来寻找磁性化合物。 人们正在从由轻质金属（如锂、镁和钙）组成的助熔剂混合物中的元素反应中寻找用于储氢和潜在航空航天应用的轻质合金。 助熔剂生长通常会产生大晶体形式的产物；这允许使用大量的表征技术，这将有助于更好地理解如何从化合物的结构和组成中得出磁性和电子特性。 这项研究将为材料化学领域的本科生、研究生和博士后研究人员提供教育，这将加强佛罗里达州立大学材料科学的发展项目。 这个高度跨学科的项目涉及与各个领域（例如化学、物理和工程学）的科学家的合作；这将使参与者了解现代科学日益复杂的本质。