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Volumn 309, Issue 5741, 2005, Pages 1700-1704

Materials science: Conversion of zinc oxide nanobelts into superlattice-structured nanohelices

Author keywords

[No Author keywords available]

Indexed keywords

NANOSTRUCTURED MATERIALS; RESONATORS; SENSORS; SINGLE CRYSTALS; SUPERLATTICES; TRANSDUCERS;

EID: 24644463174     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.1116495     Document Type: Article
Times cited : (889)

References (21)
  • 1
  • 11
    • 24644450836 scopus 로고    scopus 로고
    • note
    • See Materials and Methods provided on Science Online.
  • 12
    • 24644515027 scopus 로고    scopus 로고
    • note
    • The {1122} are typical twin planes for ZnO (20).
  • 13
    • 24644431656 scopus 로고    scopus 로고
    • in press; published online
    • P. X. Gao, Z. L. Wang, Small, in press; published online (http://dx.doi.org/10.1002/smll.200500165).
    • Small
    • Gao, P.X.1    Wang, Z.L.2
  • 14
    • 24644493022 scopus 로고    scopus 로고
    • note
    • The growth of the nanostructure occurred at a local temperature of ∼700° to 800°C in an argon atmosphere, under which the possibility of neutralizing the surface polar charges by adsorbing foreign molecules is unlikely, provided the growth occurred fairly quickly. This result is consistent with our previous studies [see (7-9)].
  • 15
    • 24644478750 scopus 로고    scopus 로고
    • note
    • From the energy point of view, a polar-surface-dominated nanobelt tends to fold itself into a ring or spring for reducing electrostatic energy (6). The nanoring is stable if the ratio between nanobelt thickness, t, and the radius, R, of the nanoring is smaller than ∼3% (8). Nanorings with t/R > 3% are energetically unfavorable to form.
  • 16
    • 24644460273 scopus 로고    scopus 로고
    • note
    • The aforementioned data rule out the possibility that the nanohelix is formed by bilayer surface strain (5) for two reasons. First, there is no bilayer strained structure in our system; and second, the difference in surface stress on the (0001)-Zn and (0001)-O of ZnO, if any, has negligible effect on the formation of nanorings or nanobows (8). The nanohelix is likely to be formed by two processes: the rigid structural alteration due to the formation of the superlattice and the spontaneous polar-charge-induced bending (6). However, t of the nanobelt is ∼20 nm, and typical R of the nanohelix is ∼150 to 350 nm (Fig. 1). Thus the t/R is ∼6 to 13%, which is much larger than the threshold value (∼3%) permitted for forming a nanoring by electrostatic polar charges (15). Also, considering the great reduction in area of the polar surfaces (for ∼50%) after forming the superlattice as well as the helical shape of the structure, the role played by polar charges in forming a helix is dramatically reduced. Therefore, the dominant mechanism for forming the nanohelix is by rigid lattice rotation and twisting as a result of superlattice formation.
  • 21
    • 24644490967 scopus 로고    scopus 로고
    • note
    • Thanks to support from NSF, the NASA Vehicle Systems Program and Department of Defense Research and Engineering, the Defense Advanced Research Projects Agency, and the Chinese Academy of Sciences.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.