| Boron and related compounds have complex structures with potential applications, which are comparable with elemental carbon and related compounds. Since carbon nanotubes was firstly found by Japanese researcher lijima, one-dimensional nanomaterilas related with boron, such as boron nitride nanotubes, boron nanowires, borate nanotubes and so on, have also attracted scientist's interests. Metastable materials are the other hotspot in modern research areas of materials. But few efforts were reported to fabricate metals-boron solid solutions from immiscible elements. In the thesis , two areas of one-dimensional nanomaterilas and metastable solid solution related with boron were explored. Synthesis methods and growth mechanism for BN nanotubes and magnesium borate nanobelts were studied. Metastable Ag-B and Cu-B solid solutions were synthesized by mechanical alloying. Thereinafter, some innovative results were achieved.1. By using crystalline boron powders with high purity as B source and metal-oxide, such as NiO, C03O4, V2O5, Y2O3 and La2O3 as catalysts, BN nanotubes have been synthesized through reacting with NH3 at high temperature. Besides, BN nanocages and nanowires were also obtained. The results showed that different products were formed by using different catalysts. Among all catalysts, La2O3 was proved to be the most effective catalyst and the yield of BN nanotubes and nanocages catalyzed by La2O3 were about 50% and 60% respectively. The growth mechanism of BN nanotubes were investigated and attributed to VLS (vapor-liquid-solid) or SLS (solid-liquid-solid) grow process.2. A new silica-assisted growth mechanism was proposed. Experimental results showed that cylinder-like and bamboo-like BN nanotubes were obtained under different reactive processes. Oxide-assisted growth mechanism and VLS or SLS mechanism can be used to interpret the formation of cylinder-like and bamboo-like nanotubes respectively. Some especial bamboo-like BN nanotubes with nanoparticles in the "knots" of tubes were observed and a capillarity growth mechanism was proposed to depict the formation of this kind of nanotubes.3. Arc discharge method was applied to synthesize BN nanotubes. Two reactive systemshave been studied. One is hexagonal BN (used as B source) with metallic Fe, Co, Ni (catalysts); the other one is B (used as B source) with metal-oxide Fe2O3, €0304, NiO (catalysts).4. BN nanotubes were also synthesized at relat ive low temperature under ambient atmospheres by using urea and boric acid as N and B sources in the presence of metal nitrate as catalyst precursors. The experimental results showed that iron nitrate was the ideal catalyst precursor. Transmission electron microscope (TEM) observation indicated that the as-prepared BN nanotubes were well crystallized and exhibited a zigzag type arrangement. Y-junction BN nanotubes were also observed in the products. Taking account of kinetic factors, the diffuse distances for the reactants atoms was shortened. The reason for the relative low formation temperature may be related with kinetic favorable factors induced by well-mixted procusors. Inevitable oxygen impurities also played an important promotive effect on the crystallization and growth of BN nanotubes at this relative low temperature.5. Single crystalline Mg3B2O6 nanobelts have been synthesized by heating the mixture of boron and nanometer-sized MgO powders under flowing mixed Ar/H2O gases at 1100 C. This one-dimensional nanostructures have not yet be reported. High resolution transmission electron microscopy (HRTEM) and select area electron diffraction (SAED) observations demonstrated that the nanobelts were single-crystalline with growth direction near to [010] direction.6. Mechanical alloying (MA) method was applied to synthesize Ag-B and Cu-B metastable solid solutions. Structural evolution during ball milling, magnetic and thermal stability were investigated. TEM observations and DSC measurements showed that the ball-milled products are the metastable. During low temperature magnetic measur...
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