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Materials Science at Oregon State University

The Role of Synthetic Levers for Control of Phase, Size and Morphology in Nanoscale Transition Metal Pnictides: Consequences for Catalytic and Magnetic Properties

Date: Thursday, May 10th
Presenter: Prof. Stephanie L. Brock, Department of Chemistry, Wayne State University

Abstract


The transition metal pnictides (pnicogen = Group 15 element) are a class of compounds that have yet to be extensively explored on the nanoscale, despite the fact that these materials exhibit a wide range of properties of interest for important technologies including thermoelectrics, batteries, data storage, and catalysis. A major challenge for understanding the properties of these phases is the lack of synthetic methods that permit formation of discrete nanoparticles with control of size, structure, stoichiometry and morphology. We have developed a number of synthetic “levers” that enable us to control these critical parameters in first-row transition metal phosphides and arsenides, and have begun to map out the role of size on structure-property relationships, with particular emphasis on magnetic and catalytic properties.
The presentation will focus on phosphides of nickel (Ni12P5 vs. Ni2P), and one arsenide case, MnAs (hexagonal vs. orthorhombic). The mechanism by which phase and size is controlled in these systems will be described, and the consequences for catalytic hydrodesulfurization in Ni2P and the first order magnetostructural transformation in MnAs, presented. The talk will conclude with a discussion of the potential generality of the synthetic “levers” uncovered and the promise of nanostructured pnictide phases for addressing critical technological needs in the 21st century.

Biography
Stephanie Brock is a native of the Pacific Northwest. She attended the University of Washington as an undergraduate (B.S. Chemistry, 1990), performing research on oxygen-atom transfer reactions under the direction of Professor James M. Mayer. Brock attended graduate school at U. C. Davis, where she worked with Professor Susan M. Kauzlarich in the area of solid state chemistry. Her dissertation focused on the synthesis and structure-magnetic property investigations of layered pnictide and pnictide oxide compounds of Mn and Zn. She graduated in March of 1995 and then stayed on for several months as a postdoctoral associate where she studied mixed metal pnictide oxides. Brock began a postdoctoral position at the University of Connecticut in August of 1995 with Professor Steven Suib. There, she developed expertise in soft chemistry routes to nanomaterials through the synthesis and characterization of novel manganese oxide colloids. She also worked with ac-glow discharge plasmas for hydrogen generation and carbon dioxide decomposition. In the Fall of 1999, Brock began a tenure-track position in the Department of Chemistry at Wayne State University and was promoted to Associate Professor with tenure in 2005 and Full Professor in 2009. She has received an NSF-CAREER award and a Research Corporation Research Innovation Award. Her research interests lie in the synthesis, properties and applications of metal pnictide and chalcogenide extended solids and nanomaterials; sol-gel methods for nanoparticle assembly, and organic- inorganic hybrid materials for biomedical applications.