Nanowires of crystalline orthorhombic sodium niobate (NaNbO 3 ), with diameters of approximately 100 nm and lengths of several to hundreds of microns, as well as cubes with edges of lengths of hundreds of nanometers were obtained by reacting niobium oxide (Nb 2 O 5 ) with 10 and 12.5 M NaOH solutions, respectively. The microstructures of the synthesized wiry and cubic piezoelectric materials were investigated, and the details of the reactions were elucidated as well. The piezoelectricity of individual NaNbO 3 (Pbma) nanowires was confirmed by piezoresponse force microscopy, and an effective piezoelectric coefficient along the vertical direction of around a few pm/V was obtained. To our knowledge, the present work is the first report of the preparation of NaNbO 3 nanowires as well as the determination of piezoelectricity.
The variation in localized surface plasmon resonances of single Au nanodisks (diameter 100 nm and height 25 nm) on 0−13 graphene layers is investigated using dark-field scattering spectroscopy to obtain the graphene electric field screening length. For nanodisks (NDs) with and without underlying graphene layers on a SiO 2 (300 nm)/Si substrate, the plasmon resonance red shifts from 604 to 620 nm with increasing graphene layers. The spectra of the plasmonic nanostructures obey an exponential saturation function versus increasing number of layers of graphene from 0 to 13. As a conducting film, the graphene layers screen the electric field generated by the plasmonic resonance of the Au NDs in the vicinity of the interface, and the red shifts of the resonance wavelength are explained in the framework of the electromagnetic field coupling between in-plane antiparallel image dipoles in the graphene layers and the ND dipole. A screening length of 1.2 ± 0.2 nm, equivalent to 3−4 graphene layers, is experimentally obtained, in good agreement with the measurement by field-effect transistors and theoretical calculation in doped graphene. The resonance shift of plasmonic nanostructures on a layered graphene system provides an alternative and convenient method for screening length measurement of graphene films.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.