Growth of metal oxide nanowires from supercooled liquid nanodroplets.
Nanometer-sized liquid droplets formed at temperatures below the bulk melting point become supercooled as they grow through Ostwald ripening or coalescence and can be exploited to grow nanowires without any catalyst. We used this simple approach to synthesize a number of highly crystalline metal oxide nanowires in a chemical or physical vapor deposition apparatus. Examples of nanowires made in this way include VO(2), V(2)O(5), RuO(2), MoO(2), MoO(3), and Fe(3)O(4), some of which have not been previously reported. Direct evidence of this new mechanism of nanowire growth is found from in situ 2-dimensional GISAXS (grazing incidence small angle X-ray scattering) measurements of VO(2) nanowire growth, which provides quantitative information on the shapes and sizes of growing nanowires as well as direct evidence of the presence of supercooled liquid droplets. We observe dramatic changes in nanowire growth by varying the choice of substrate, reflecting the influence of wetting forces on the supercooled nanodroplet shape and mobility as well as substrate-nanowire lattice matching on the definition of nanowire orientation. Surfaces with defects can also be used to pattern the growth of the nanowires. The simplicity of this synthesis concept suggests it may be rather general in its application.
Department of Chemistry & Biochemistry, University of California at Santa Barbara, California 93106, USA.
Myung Hwa
MH
Kim
Byeongdu
B
Lee
Sungsik
S
Lee
Christopher
C
Larson
Jeong Min
JM
Baik
Cafer T
CT
Yavuz
Sönke
S
Seifert
Stefan
S
Vajda
Randall E
RE
Winans
Martin
M
Moskovits
Galen D
GD
Stucky
Alec M
AM
Wodtke
D003080:Cold Temperature; D003460:Crystallization / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D012996:Solutions / Q000737:chemistry*; D013499:Surface Properties
D046911:Macromolecular Substances; D010087:Oxides; D012996:Solutions