The CuO/Cu2O nanowire axial heterostructures were fabricated by a thermal oxidation technique in air. These nanowire structures resulted from CuO nanowire growth followed by Cu2O formation. These nanowires were divided into two regions. One is the top half part of the nanowire with CuO domains, and the other part is the bottom half of the wires with Cu2O domains. The structural property of the CuO/Cu2O nanowire axial heterostructures was clarified in detail. Both the CuO and the Cu2O have domain boundaries parallel to the growth direction. The specific relationship of the crystalline orientation between the CuO and Cu2O shows that CuO [110] or [110] is nearly parallel to Cu2O [110] mostly along the growth directions. The growth condition dependence of the morphological structure was also examined. A simple axial nanowire heterostructure fabrication technique using the compositional modification was developed.

AlN-SiC solid solutions were synthesized via a combustion nitridation process. Reactions between powder mixtures of aluminum, silicon, and carbon or aluminum with ␤-SiC and gaseous nitrogen under pressures of 0.1-8.0 MPa are selfsustaining once they have been initiated. Investigations were made with reactant ratios of Al:Si:C ‫؍‬ 7:3:3, 6:4:4, and 5:5:5 and Al:SiC ‫؍‬ 7:3, 6:4, and 5:5. For the Al-Si-C system (molar ratio of 6:4:4), the maximum combustion temperature was dependent on the nitrogen pressure, increasing from 2300°C to 2480°C with an increase in pressure, from 0.1 MPa to 6.0 MPa. In all cases, the product contained the solid solution as the primary phase, with minor amounts of silicon. The amount of unreacted silicon decreased as the nitrogen pressure increased; the presence and dependence of unreacted silicon on pressure has been explained in terms of the volatilization of aluminum. The full width at half maximum for the (110) peak of the AlN-SiC solid solution decreased as the nitrogen pressure increased, which indicated the formation of a more homogeneous product.

The synthesis of solid solutions of AlN-SiC was investigated through the combustion reaction between Si 3 N 4 , aluminum, and carbon powders and nitrogen gas at pressures ranging from 0.1 to 6.0 MPa. The combustion reaction was initiated locally and then the wave front propagated spontaneously, passing through the cylindrical bed containing the loose powder. In the presence of Si 3 N 4 as a reactant, it was feasible to synthesize solid solutions at an ambient pressure (0.1 MPa). The relationship between nitrogen pressure and full-width at half-maximum of the (110) peak of the product showed that lower pressures produced more-homogeneous solid solutions. Some aspects of formation of the AlN-SiC solid solutions were discussed with special emphasis on the influence of nitrogen pressure and reactant stoichiometry.

The hexagonal phase MoSi2 was grown using MoS2 powder as the source material by the molten salt method. The structural and morphological properties of the resultant silicides are characterized. As a comparison, the structural and compositional characterizations were made for the Mo-silicides grown on a Mo substrate and a Mo-Ti alloy compact. It was revealed that the homogeneity of the chemical composition of the silicides grown using MoS2 is improved, except for the existence of the Si source powders, though a small amount of S remained in the powder. The layered structure of MoS2 with a hexagonal crystalline structure would affect the growth morphology and enhance the formation of the hexagonal MoSi2. A simple growth procedure to fix the crystalline structure using an appropriate starting material under a preferable growth environment is proposed.

Various kinds of Ag nanostructures were grown on various metallic substrates using hexakisphosphate (IP6) as a silver carrier agent. The Ag nanostructures with three-dimensional dendritic structure, the two-dimensional dendritic structure, the two-dimensional fractal structure, particles and nanowire structures were controllably obtained. The morphological control by IP6 using additional metallic materials is proposed. The structural properties of the Ag nanostructures were examined, and the growth evolution of the nanostructures was discussed. It is considered that the IP6 plays an important role as a silver carrier agent for the structural and morphological control of the Ag nanostructures.