William Petuskey

My research group focuses on the physical chemistry of ceramics, glasses and wide band-gap semiconductors. We seek to find new compounds, or modifications of known materials, with special properties suitable for electronic, optic, electrochemical and mechanical applications. The approach is to design new materials by manipulating both crystal chemistry and microstructure of solids. A wide variety of synthetic techniques are employed, ranging from the soft chemical approaches of solution and vapor chemistry to the hard chemical approaches of extreme temperatures and pressures.

The manipulation of microstructures implies the introduction and control of grain boundaries and phase boundaries, which often impart radically different physical properties to solids than would have been expected of single crystals. Taken to the extreme of nanoscaled organization, we are developing “soft-ceramics” that combine high temperature stability in oxidizing and corrosive environments with mechanical toughness. To achieve this, one project investigates the crystal chemical alteration of layered perovskites to produce mica-like materials that are stable to greater than 1500°C, but yet can be easily machined into complex shapes. Another project is devoted to investigating the chemistry of very high temperature glasses as precursors to forming ductile-like nanocomposites. Paradoxically, this is achieved by developing finely divided microstructures of two brittle solids.

With respect to electronic materials, we are investigating the chemistry of icosahedral boride compounds for use as wide bandgap semiconductor materials. Beginning with our early work on B12O2 that produced elegant icosahedral morphologies of individual grains (as shown), we have expanded our research to examine the physical and chemical properties of other compositions of the general formula fo B12X 2, where X is typically a main group element. Another project focuses on the thermochemistry and phase chemistry of electroceramics that are targeted for use in piezoelectric, ferroelastic and optical transducers. The importance of this work relates to controlling the crystal growth of complex oxides.