Broad Beam-Induced Fragmentation and Joining of Tungsten Oxide Nanorods: Implications for Nanodevice Fabrication and the Development of Fusion Reactors

In
this work, for the first time, fragmentation and joining of
tungsten oxide (WO3) nanorods induced by a broad ion beam
are reported. Although at low energy (5 keV) and moderate ion fluence,
nanorods fragment into smaller pieces along the length, at higher
ion energies (50–100 keV), a contrary process occurs, which
leads to the joining of the nanorods. A state-of-the-art ion–solid
interaction simulation, namely, TRI3DYN, has been invoked to explore
the possible mechanisms that reveal subtle contributions of surface
defects, ion-beam mixing, and sputtering. High-resolution electron
microscopy, photoluminescence study, and X-ray photoelectron spectroscopy
support the observed results and proposed mechanisms. Such modifications
have interesting effects on the electrical conductivity of the nanorod
assembly. The change in sample color upon ion irradiation from initial
white to yellow, light blue, deep blue, light green, and cyan shows
an excellent and reversible chromatic response of tungsten oxide nanorods
to irradiation. Such a property can be exploited to fabricate radiation
sensors. The fragmentation and joining at different energy scales
have essential implications in nanodevice fabrication through the
bottom-up approach as well as for the development of fusion reactors.