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Physics

Physics Department Current Events


Wednesday, November 26, 2014
Joint Chemistry Physics Colloquium
12:00 p.m., (NOTE TIME CHANGE) Marshak Science Building, Room 418N

Joel S. Miller
Professor, Chemistry Department,
University of Utah, Salt Lake City, Utah

“Organic-based Magnets:New Chemistry, Physics, and Materials for this Millennium
(New Magnets for Your Future)”


Molecule-based materials exhibiting the technologically important property of bulk magnetism have been prepared and studied in collaboration with many research groups worldwide frequently exhibit supramolecularextended 3-D structures. These magnets are prepared via conventional organic synthetic chemistry methodologies, but unlike classical inorganic-based magnets do not require high-temperature metallurgical processing. Furthermore, these magnets are frequently soluble in conventional solvents (e. g., toluene, dichloromethane, acetonitrile, THF) and have saturation magnetizations more than twice that of iron metal on a mole basis, as well as in some cases coercive fields exceeding that of all commercial magnets (e.g., Co5Sm). Also several magnets with critical temperatures (Tc) exceeding room temperature have been prepared. In addition to an overview of magnetic behavior, numerous examples of structurally characterized magnets made from molecules will be presented. Our groups has discovered 8 families of molecule-based magnets, mostly organic-based, and have significantly contributed to an eight family based upon the Prussian blue structure. Four examples magnetically order above room temperature and as high at 127 oC.These will include [MIII(C5Me5)2][A], [MnIII(porphyrin)][A] (A = cyanocarbonetc. electron acceptors) as well as M[TCNE]x, which for M = V is a room temperature magnet that can be fabricated as a thin film magnet via Chemical Vapor Deposition (CVD) techniques. A newer class of magnets of [Ru2(O2CR)4]3[M(CN)6] (M = Cr, Fe; R = Me, t-Bu) composition will also discussed. For R = Me an interpenetrating, cubic (3-D) lattice forms and the magnet exhibits anomalous hysteresis, saturation magnetization, out-of-phase, c"(T), AC susceptibility, and zero field cooled-field cooled temperature-dependent magnetization data. This is in contrast to R = t-Bu, which forms a layered (2-D) lattice.Additionally, new magnets possessing the nominal Prussian blue composition, M'[M(CN)6]xand (Cation)yM'[M(CN)6], but not their structure, will be described. The organic chemistry crucial to designing and preparing organic-based magnets will be discussed.


 




Joel S. Miller


Joel S. Miller, Professor, Chemistry Department, University of Utah, Salt Lake City, Utah