Kinetics Measurements at the Nanoscale Ivar E. Reimanis , Colorado School of Mines, DMR 1003030

1. Nanoscale Magnetic Behavior of Doped OxidesIvarE. Reimanis, Colorado School of Mines, DMR 1003030 A small amount of dopant can have a huge influence on the way ceramics are made (and hence, their cost) and their properties, such as ionic conductivity, catalytic behavior, transparency, and mechanical behavior. Finding out where the dopants reside, may be extremely challenging. Magnetometry offers a solution, particularly when the dopants are present at the nanoscale. At right, graduate student Amy Morrissey loads a specimen of zirconia doped with a small amount of nickel atoms (a material used in fuel cell electrodes) into a magnetometer to study the magnetic signatures that are correlated to structure. A nickel atom does one of three things: (1) occupies a random location in the host, (2) joins an ordered assembly as an oxide, or (3) combines with other nickel atoms, and magnetometry can tell the difference. Second year Colorado School of Mines PhD student, Amy Morrissey, inserts a specimen into a SQUID magnetometer at NIST in Boulder, CO. (courtesy of Ron Goldfarb, NIST).

2. Kinetics Measurements at the NanoscaleIvarE. Reimanis, Colorado School of Mines, DMR 1003030 Internal reduction is the process by which nanometer size metal particles form within an originally all-ceramic material. Such composites show behavior not seen when conventional processing is used. In the example at right, nickel metal precipitates out of solution from zirconia, leading to a large metal surface area that benefits catalysis. If the nickel particle size is below about 3 nm, the material becomes superparamagnetic. The Reimanis group at Colorado School of Mines is developing models to describe how nickel (and other metals) precipitate from their oxide hosts. SQUID magnetometry is used to detect the early stages of nucleation and growth so that one may fine-tune the nanostructure. Ni0 Above, an electron microscope image shows nickel metal in a matrix of zirconia, produced by internal reduction. Below, SQUID magnetometry performed in two separate measurements, reveals the formation and growth of nickel.