Synthesis of Ultrafine SnO_2-x Nanocrystals by Pulsed Laser-Induced Reactive Quenching in Liquid Medium

Abstract

We present the first synthesis of ultrafine tin oxide nanocrystals (2 to 3 nm) by pulsed laser ablation of a tin metal plate in aqueous solutions of sodium dodecyl sulfate (SDS) and in pure water. The particle size, phase structure, and surface states are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Surfactant effects on the formation of tin oxide nanocrystals are also examined. Stable colloidal suspensions consisting of well-dispersed tin oxide nanocrystals with very narrow size distribution could be obtained with surfactant solution around the critical micelle concentration, and the formation of metal droplets was significantly suppressed. Optical transmittance spectrum analysis indicated that the optical gap of SnO 2-x nanocrystals increased to 3.81 eV with an average size of 2.5 nm due to quantum size effects. XPS investigation revealed that the valence of Sn in oxide nanoparticles surface is not four, but rather around three. A possible formation process of tin oxide is proposed based on laser-induced reactive quenching and surfactant-mediated growth. This unique technique could be extended to prepare other oxide nanocrystals.

Gold/Tin Oxide Nanocomposite by Nanojoining

“…The solution remained colorless but appeared turbid after the ablation process. The formation of tin oxide NPs can be explained on the basis of pulsed laser induced reactive quenching in liquid medium [13]. In case of laser ablation of transition metal targets the surrounding liquid not only confines the ablated species at the liquidsolid interface but also acts as a mediator for chemical reaction at the liquid-solid interface.…”

“…(1). The pH value of the oxide NPs in pure water is below the isoelectric point indicating that the particles are positively charged at the surface [13]. We have carried out ablation in the absence of any surfactant so the positively charged NPs initially repel each other due to electrostatic repulsive forces.…”

Enhancement of adhesion ability and high-temperature stability of silver paste film by incorporation of SnO2 conducting oxide

“…The presence of SnO x bonds agreed well with a decrease in the sheet resistance of the composite silver paste film because a presence of SnO x corresponded to oxygen deficient state of SnO 2 . 15) In case of O 1s photoemission spectra as shown in Fig. 4(b), there was not specific difference between the cases of Al and ITO substrate besides oxygen bonds with each electrode substrate: OAl and OIn.…”

Template-free synthesis of hierarchical porous SnO2

“…In the case of the O 1s peaks, a shoulder at *531.5 eV is observed with the main peak at *530.3 eV. The main peak is assigned to the lattice oxygen, and the shoulder is due to the oxygen of the Sn-OH bonds [31,32].…”