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A novel low-temperature sol-gel-based process has been developed for the synthesis of amorphous and crystalline powders in the Al-O-N system. The process involves reacting aluminum tri-sec-butoxide with anhydrous hydrazine using a solvent mixture of acetonitrile (ACN) and chloroform (at ≈60 °C) to result in solid precursors. The as-prepared precursors have been pyrolyzed in nitrogen and in anhydrous ammonia to yield amorphous and crystalline oxynitride or nitride powders. The powders have been characterized using X-ray diffraction (XRD), fourier transform infrared (FTIR), and 27 Al magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy techniques. Results of the structural spectroscopic analyses conducted on the pyrolyzed powders obtained at 800 °C indicate the formation of an amorphous or nanocrystalline aluminum oxynitride containing Al bonded to O in buta-, penta-, and hexacoordination. Evidence is also presented suggesting the influence of hydrazine in facilitating replacement of the butoxy groups during heat treatment and creating molecular species containing Al-N linkages in the solid precursor. Continued heat treatment of these precursors in NH 3 at 1300 °C leads to the formation of crystalline AlN. The role of hydrazine in the formation of the nitride was also verified by conducting the reaction using controlled amounts of deionized (DI) water. The addition of water competes with the nitridation ability of hydrazine leading to the formation of either oxides or oxynitrides of aluminum. The approaches thus developed demonstrate the potential and flexibility of alkoxides for synthesizing precursors that lead to either single phase of AlN or molecularly mixed composites of Al 2 O 3 , AlON, and AlN, in the Al-O-N system.

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A thio sol-gel process for the synthesis of titanium disulfide using titanium alkoxide as the metal source is demonstrated. The alkoxide reacts at room temperature with H,S to form a precipitate which is a precursor to the sulfide. Through infrared spectroscopy and chemical analysis of the powder and gas chromatographic analysis of the liquid byproducts of the reaction, it is shown that a partially sulfidized alkoxide precursor forms through the displacement of alkoxy groups from the alkoxide by sulfur-bearing thiol groups. This thiolysis reaction is very similar to that which occurs in the case of sol-gel reactions to form oxides. The alkoxy-thiol species then undergo condensation-polymerization by the liberation of H,S. When it is heat-treated in H,S, this precursor transforms to TiS, at -700°C. Systematic heat treatments have been performed and the formation of TiS, has been observed using X-ray diffractometry. The change in the morphology has also been studied using scanning electron microscopy.