Doped Ceramics in India Ivar E. Reimanis , Colorado School of Mines, DMR 1003030

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Ivar E. Reimanis, Colorado School of Mines, DMR 1003030

Colorado School of Mines undergraduate student, Scott Harper (2nd from right) at the Indian Institute of Science.

Colorado School of Mines undergraduate Scott Harper is spending the summer at the Indian Institute of Science to collaborate with Prof. Atul Chokshi’s research group (top picture). Scott is a top Mines student who is highly community-active, and his unique experience in India will impact many of his fellow students. For his project, he examines how dopants can have huge influences on the way ceramics are made (and hence, their cost) and their properties, such as ionic conductivity, catalytic behavior, transparency, and mechanical behavior. The lower figure shows fracture surfaces of Scott’s materials (yttria-stabilized zirconia, or “YSZ”), as hot-pressed (left) and heat treated (right). The porosity (Swiss cheese appearance) that develops from the heat treatment is related to the amount of dopant present, but the reason for it is not understood and is currently being studied.

Fracture surfaces of nickel-containing YSZ, as processed (left). Grain growth and swelling resulted from a heat treatment (right).

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Internal reduction is the process by which nanometer size metal particles form within an originally all-ceramic material. This leads to behavior important for applications such as energy conversion and catalysis. In the example at right, nickel exsolution from zirconia, is studied by electron microscopy and SQUID magnetometry. The top image reveals that Ni metal nucleates at the grain boundary, in registry with one of the grains. A fundamental understanding of the mechanism of early stages of nucleation does not exist, but would enable grain boundary engineering for desired material properties. The lower picture shows magnetometry data that tracks internal reduction with time. The Reimanis group at Colorado School of Mines is developing models to describe how nickel (and other metals) precipitate from their oxide hosts.

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

Above, an electron microscope image shows nickel metal in a matrix of zirconia, produced by internal reduction. Image was taken at PNNL in collaboration with CSM Professor Brian Gorman. Below, SQUID magnetometry performed in two separate measurements, reveals the formation and growth of nickel.