抄録
[Introduction]
Ionic liquids (IL) have excellent characteristics such as ionic conductivity, thermal and chemical stability, and nonvolatility. It is known ionic liquids as chemical reaction field can be used. The metal nanoparticles can be synthesized by sputtering metal atoms into ionic liquids [1]. Moreover, the transition metal nanoparticles as catalyst progress to form nano carbon materials by chemical vapor deposition. The shape of this nanoparticles is possible to influence the properties of nanocarbon materials [2]. The understanding of the process of nanoparticle formation by transition metal atoms and the control technique of its shape are important. On previous work, we have observed that the behavior of the ionic liquid molecules and transition metal atoms may be different with each surface structure (Si-rich or C-rich) on transition metal deposited IL/SiC surface. So, we focused on Si-rich surfaces, the surface structure was observed to clarify the behavior of transition metal atoms on the IL covered Si surface after annealing and the formation process of nanoparticles. In this study, the nanoparticle formation was carried out in a vacuum environment, but in order to simplify the process, formation of nanoparticles was attempted in the air.
[Experimetal]
The sample was Si(100) substrates. The ionic liquid was 1-ethyl-3-methylimidazolium bis(triflumethylsulfonyl)imide ([EMIm]Tf2N). At first, ionic liquid dropped on the substrate in the air. Next, the platinum (Pt) as transition metal material was deposited on the surface by a magnetron sputtering system. The samples were annealed in the air at below 350 oC for 10 minutes. The surface structures were observed by scanning electron microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray diffraction (XRD). The annealing temperature was measured by pyrometer.
[Result]
The samples with varying Pt film thickness from 10 to 40 nm were prepared. Figure 1 shows an SEM image of the Pt (20 nm) deposited [EMIm]Tf2N/Si(100) surface with annealing at 200 oC for 10 minutes in the air. The many nanoparticles were observed on the surface. SEM and EDS results of this surface suggested that Pt nanoparticles covered with ionic liquid was dispersed on the surface. XRD observation of the sample further indicated the possibility of Pt silicide formation. In this presentation, we will report the observation results of the surface structure when the amount of Pt deposited is varied up to 40 nm and the substrate annealing temperature is also varied.
[References]
[1] T. Torimoto, et. al., Appl. Phys. Lett., 89, 243117 (2006).
[2] T. Ikari et al., Surf. Rev. Lett., 16, 761 (2009).
