Doping and planar defects in the formation of single-crystal ZnO nanorings

Abstract

We have recently reported the growth of freestanding, single-crystal, seamless nanorings of zinc oxide via a spontaneous self-coiling process during the growth of polar-nanobelts [X.Y. Kong et al., Science 303, 1348(2004]. The nanoring is made by coaxial and uniradius loop-by-loop winding of a fine ZnO nanobelt. An important fact is that each and every nanoring is made of a nanobelt that contains basal-plane planar defects, which are suggested to be important for leading the fastest growth of the nanobelt as well as lowering its elastic deformation energy. In this paper, high-resolution transmission electron microscopy is applied to investigate the nature of the planar defects in the nanobelts and in nanorings. The planar defects were initiated and formed by single-layer segregation of the doping element, such as indium, which was introduced in the growth process. The accumulation of impurity ions forms two vicinal Inu O octahedral layers parallel to the basal plane. They form "head-to-head" and "tail-to-tail" polar-inversion domain boundaries. For a nanobelt that self-coils into a nanoring, we found that the head-to-head and tail-to-tail polar-inversion domain boundaries are paired, thus, the polarity of the nanobelt is unchanged. Therefore, our data support the proposed model [X.Y. Kong et al., Science 303, 1348(2004] that the nanoring is initiated by circularly folding a nanobelt due to long-range electrostatic interaction between the surface polar charges on the two sides, and a loop-by-loop winding of the nanobelt forms a complete ring.

Self‐Assembly and the Properties of a Highly Oriented Hierarchical Nanobelt–Nanoprism Array of Ternary Oxide Zn–In–O

“…HRTEM and selected-area electron diffraction (SAED) recorded from the side-lying nanobelt further reveal the existence of the stacking faults along the c axis. The switched growth direction from [0001] to , the existence of large polar surfaces, and the stacking faults are in good agreement with the previous reports [21,27] on Indoped ZnO nanobelts; therefore, the switch in direction here and the stacking fault formation during the growth www.eurjic.orgshould also be attributed to the structural modulation induced by In doping. It is worth mentioning that in most previous studies, successful doping will usually be accompanied by the degradation of the alignment/symmetry for a nanostructure array; in contrast, here, not only is successful In doping achieved for the ZnO nanobelts but also the alignment and in-plane symmetry is well preserved.…”

“…Taking In-doped ZnO 1D nanostructures as an example, it has been found that the growth direction and the morphology of the nanostructures can be dramatically changed due to In doping. [20][21][22][23] However, nanodevice applications require not only the doping and the superlattice realizations for these 1D nanostructures but also the good order and high quality of the selfassembly (which is crucial for the integration); clearly, the current approaches based on self-assembly cannot meet this criterion and more efforts are therefore urgently needed. Furthermore, few efforts have been made to improve the quality of hierarchical 1D nanostructure assembly [24,25] despite its importance in building bottom-up, self-assembled 1D nanomaterial circuits.…”

Role of OH− in the low temperature hydrothermal synthesis of ZnO nanorods

“…In the presence of NH 3 above which the nanostructure may be formed in hydrothermal ZnO synthesis. In this study, the growth of ZnO nanorods in zinc sulfate solution was observed from a solution pH of 10.3.…”

Indium-zinc-oxide nanobelts with superlattice structure

“…11,12 Quantitative analysis of the nanorings showed the atomic ratio In:Zn of about 1:15 suggesting In incorporation into the ZnO lattice, instead of the formation of the compound Zn 4 In 2 O 7 observed in the nanobelts of this work. The formation of nanorings by rolling up of nanobelts is explained 13 by a reduced overall dipole moment, and hence a reduction in electrostatic energy, in a circular ring.…”