Mixed Molten Metals as Solvents for Materials Synthesis

Florida State University, Tallahassee FL

Investigators

Abstract

Non- Technical Abstract This research project explores the synthesis of new semiconductors and magnetic materials by carrying out reactions using molten metals as solvents. Synthesis in metal flux allows reactions to take place in a solution; this liquid state method enables crystal growth and the formation of unusual new compounds. The new materials discovered in this work may possess useful magnetic and electronic properties, and their study contributes to increasing understanding of the nature of magnetic alloys, solar cell materials, and hydrogen storage alloys. This interdisciplinary research project educates undergraduate and graduate student researchers in materials chemistry. The work involves collaboration with scientists in a variety of areas (such as chemistry, physics, and engineering), as well as the use of advanced facilities at national labs such as Oak Ridge National Laboratory and the National High Magnetic Field Laboratory. This allows the student participants to understand the increasingly complex and collaborative nature of modern science. Technical Abstract Support from the Solid State and Materials Chemistry program in the Division of Materials Research allows the research team to explore two areas: the synthesis of magnetic alloys in lanthanide/transition metal (Ln/T) eutectic fluxes, and the synthesis of lightweight complex salt-like compounds in alkaline earth-rich (AE) flux mixtures. Products of these reactions are characterized by X-ray diffraction, magnetic susceptibility measurements, transport measurements, band structure calculations, and other techniques. Trends in reactivity, common structural building blocks, and structure-property relationships are investigated. The Ln/T flux syntheses yield new compounds with magnetic properties stemming from both the lanthanide and the transition metal element. Product structures often contain clusters or layers of transition metals; the magnetic behavior of these building blocks will shed light on how magnetic moments develop as transition metal clusters increase in size. Magnetic behavior that may arise includes magnetic ordering, spin glass behavior, superconductivity, magnetoresistance, mixed valence and heavy fermion behavior. Alkaline earth-rich flux mixtures using calcium, strontium, or barium will strongly reduce most main group elements to form new Zintl phases and complex salts. These include new metal hydride and subhydride phases which may be of interest for hydrogen storage. Using magnesium-rich fluxes yields more borderline products which do not exhibit complete charge transfer and are often semimetallic; they may be of potential use as thermoelectric materials, or may show metal-to-insulator transitions.