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Pictured is a tiny hollow iridium wire
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Pictured is a tiny, hollow iridium wire

May 7, 2010
A tiny, hollow iridium wire used as a reaction vessel for materials research. The wire is only one millimeter in diameter, the hollow just over half a millimeter. Inside is yttrium aluminum garnet (YAG), a material important for laser devices. It can be melted and supercooled to a tiny glassy drop that reveals what scientists call density driven phase separation--the same molten material solidifies in two ways. Small blobs scattered throughout the sample are not as dense as the matrix. The vertical line seen in the picture is a crack that formed during cooling.

More about this Image Paul McMillan and members of the Arizona State University's Materials Research Group are researching new chemistry processes that involve the use of immense amounts of pressure to compress materials and alter their molecular structure. These processes are similar to those that occur to rocks and minerals deep within the Earth and other planets. The group focuses on chemical compositions that may provide new types of materials that could be used in emerging technologies. McMillan is trying to develop a new way of carrying out chemistry. Most processes for making new materials use temperatures and chemical composition as the variables. The use of pressure is virtually unknown.

McMillan's research is supported by a grant from the National Science Foundation's Division of Materials Research.