Applications of molecule/polymer-based magnets

Background

Traditional magnetic materials are prepared by high-temperature metallurgical methodologies. Molecule-based organic/polymeric magnetic materials are materials prepared through the established low-temperature synthetic procedure of organic, organometallic, and coordination metal synthetic chemistry, such that at least one type of spins site is based on s and/or p orbitals.

The inherent low densities and high molecular masses of molecule/polymer-based magnets mean that bulk applications relying on high magnetic moments either on a mass or volume basis are unlikely. In contrast, other uses such as for inductors (for example, as the core material in transformers) that guide magnetic fields and for magnetic shielding of low-frequency magnetic fields are feasible. The high permeability to mass ratio make this class of soft (low coercive fields) magnetic materials potentially attractive for lightweight transformers, generators and/or motors as well as dc and low frequency shielding applications [1].

Recent Advances

The potential for our room-temperature V(TCNE)x y(solvent) magnet in this area has been established [2]. (V(TCNE)x y(solvent) [3] is magnetic at room temperature, its extrapolated Tc being about 400 K (125 oC), above its decomposition temperature of 350 K.) The V(TCNE)x y(solvent) magnet also has the attributes of low power loss and flexible low-temperature processing -key technological advantages.

In addition, the "prussian blue" system V[Cr(CN)6]0.86 2.8H2O [4], has been used as a temperature activated magnetic switch. (The "prussian blue" systems have a tinkertoy structure with M-CN-M' linkages in 3-D, where M and M' are transition metal ions like V, Cr, Mn, Ni, etc.. Recent studies of such materials showed high temperature magnetism.)

Publications

J.S. Miller and A.J. Epstein, Molecular and Polymeric Magnets, Chemistry and Industry, 49-53 (1996).

B.G. Morin, P. Zhou, C. Hahm, A.J. Epstein, and J.S. Miller, Complex AC Susceptibility Studies of the Disordered Molecular Based Magnets V(TCNE)x: Role of Spinless Solvent, Journal of Applied Physics 73, 5648-5650 (1993).

J.M. Manriquez, G.T. Yee, R.S. McLean, A.J. Epstein, and J.S. Miller,  A Room Temperature Molecular/Organic-Based Magnet, Science 252, 1415-1417 (1991).


Created by Darren Gebler and Mihai Gîrtu. Maintained by John Rohrbacher. Last updated 6/2/00.