Bierman Matthew J, Lau Y K Albert, Kvit Alexander V, Schmitt Andrew L, Jin Song
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
Science. 2008 May 23;320(5879):1060-3. doi: 10.1126/science.1157131. Epub 2008 May 1.
Hierarchical nanostructures of lead sulfide nanowires resembling pine trees were synthesized by chemical vapor deposition. Structural characterization revealed a screwlike dislocation in the nanowire trunks with helically rotating epitaxial branch nanowires. It is suggested that the screw component of an axial dislocation provides the self-perpetuating steps to enable one-dimensional crystal growth, in contrast to mechanisms that require metal catalysts. The rotating trunks and branches are the consequence of the Eshelby twist of screw dislocations with a dislocation Burgers vector along the 110 directions having an estimated magnitude of 6 +/- 2 angstroms for the screw component. The results confirm the Eshelby theory of dislocations, and the proposed nanowire growth mechanism could be general to many materials.
通过化学气相沉积法合成了类似松树的硫化铅纳米线分层纳米结构。结构表征显示，纳米线主干中存在螺旋状位错，外延分支纳米线呈螺旋状旋转。研究表明，轴向位错的螺旋分量提供了使一维晶体生长得以持续的台阶，这与需要金属催化剂的机制不同。旋转的主干和分支是螺型位错的埃舍尔比扭转的结果，其位错伯格斯矢量沿110方向，螺型分量的估计大小为6±2埃。这些结果证实了位错的埃舍尔比理论，并且所提出的纳米线生长机制可能适用于许多材料。
