ZnO纳米电缆的制备、结构和生长机理

以混合的锌粉和锡粉作为原料, 通过热蒸发的方法在沉积有金膜的硅基片上制备出具有“芯线-壳层”同轴结构的ZnO/SiO_x纳米电缆. 扫描和透射电镜的研究表明, 这种纳米电缆的产量很高, 长度达到数个微米, 并且确认了其“芯线-壳层”的独特结构. 不同于以往ZnO一维纳米材料的三个快速生长方向〈0001〉、〈0110〉及〈2110〉, 其ZnO芯线的生长方向为2021]. 本实验中锡粉和金膜分别作为抑制剂和催化剂, 通过控制锌粉的蒸发速率以及金硅共熔反应使ZnO纳米电缆在硅基片上得到一维生长. 这种纳米电缆可望在纳米尺度的电路、电器以及力学和光学信号的耦合和转换方面得到应用.

Synthesis, Growth Mechanism and Microstructure of ZnO Nanocables

ZnO nanocables were synthesized on gold coated silicon(100) substrate by zinc powder evaporation at 550 ℃. The source materials were pure zinc and tin powders with mass ratio of 1∶1 and the experiment was carried out under a constant flow of Ar(98%)/O₂(2%) gas mixture(300 sccm(standard cubic centimeters per minute) in a quartz tube. SEM images showed that the nanocables were obtained in large-scale and the diameters and lengths of the nanocables were about 50 nm and several micrometers respectively. XRD, TEM and EDX investigations confirmed the core-shell structure, i.e. the core zone was single crystalline ZnO and the shell zone was SiOx amorphous layer. Interestingly, the ZnO core was grown along a unique direction of 2021], which was quite different from the conventional fast growth direction of〈0001〉,〈0110〉 and 〈2110〉of 1D ZnO nanoscale materials. A possible mechanism was also proposed. Firstly, gold film served as catalyst and the nanocables grew out from the surface of Au-Si-Zn liquid alloys；secondly, tin powders were used as inhibitor to keep a low partial pressure of zinc vapor.