| The industrial demand for high quality yet inexpensive, advanced materials is higher today than ever before. The electronics and aerospace industries spend billions of dollars attempting to stream-line materials manufacturing processes and searching for better materials to use in future devices. Solid-state chemistry can provide the solution to these problems. The research presented here can be divided into two different parts. The first section describes the synthesis of two group III-V direct band gap semiconductors, GaN and InN. These so-called "optoelectronic" materials are already being used in the fabrication of white LED's, flat panel displays, and lasers. Traditional synthetic techniques often result in low yields and/or require hours or days to synthesize these materials. The products produced in this manner are often poorly crystalline and/or contain impurities. Solid-state metathesis (double exchange) reactions are presented and shown to produce high quality, phase pure GaN in a matter of seconds. Additionally, high pressure solid-state metathesis reactions are used to produce phase pure InN. Both GaN and InN forming metathesis reactions are fast and utilize inexpensive precursors, enabling the production of these III-V semiconductors at costs potentially much lower than current industrial methods.; The second section describes the synthesis of a new class of ultrahard, incompressible materials based on the structure of osmium diboride (OsB 2). These materials are synthesized by direct combination of the elements, solid-state metathesis, and arc melting. The incompressibility (bulk modulus, B0) of many materials is shown to vary with the valence electron density. OsB2 has a very high valence electron density and was consequently found to have a very high bulk modulus and a hardness exceeding that of sapphire. The hardness of OsB2 was increased by creating solid solutions with Re (Os1-xRexB2), Ru (Os1-xRuxB2) and Fe (Os1-x FexB2). The hardness of these solid solutions was much higher than their progenitors, with some materials approaching the hardness of c-BN, the second hardest known material. Finally, solid solutions with Fe exhibit strong ferromagnetic behavior. |
