Photon Factory Activity Report 2022 #40 (2023)

BL-27A, BL-27B/2022G039

Characterization of metal nanocomposite synthesized by ion implantation intoamorphous SiO2
F. Hori1*, T. Yamada1, S. Matsuo1, A. Iwase1, T. Matsui1, N. Taguchi2, S. Tanaka2, S. Semboshi3
1
Osaka Metropolitan University, Sakai, Osaka, 599-8570, Japan
2
National Institutes of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda,
Osaka, 563-0026, Japan.
3
Tohoku University, Sendai, Miyagi, 980-8577, Japan

2 Experimental
Amorphous silica glass (SiO2: 5 × 5 × 1 mm3) was used
as an implantation target. The target was irradiated with
380 keV Ag ions and 200 keV Ni ions at room temperatureby using ion implanter at TIARA, National Institutes for
Quantum and Radiological Science and Technology (QSTTakasaki). Dual irradiation with Ag and Ni ions has doneby changing irradiation order (AN: is irradiated firstly with
Ag ions and followed by Ni ions, NA: is vice versa). Theirradiation fluence of Ag ion is 5×1015 to 7×1016 /cm2 andthat of Ni ions was 1×1015 to 1×1017 /cm2. In order toestimate the structure of synthesized nanocomposites in
SiO2, these samples were examined by XPS and EXAFS
using X-ray at KEK BL27A and B, Grazing Incidence Xray Diffraction (GIXD) and Scanning TEM with Energy
dispersive X-ray spectroscopy (EDX) analysis. Also, thecharacteristic feature of these samples was measured byscanning TEM with energy dispersive X-ray spectroscopy(EDS) and UV-vis spectroscopy. Fig.1 shows the depth
profiles of implanted ions of 380 keV Ag and 200 keV Ni
calculated by TRIM, as compared with the result different

energy of ions irradiated. By adjusting the ion energy, it ispossible to deposit different ions to the same depth.
3 Results and Discussion
Figure 1 shows the UV-vis absorption spectra of Ag-Ni
and Ni-Ag irradiation ordered samples. In general, it is
known that some metal nanoparticles exhibit absorption
peaks in the visible light band due to surface plasmon
resonance (SPR) of electrons. In this figure, it can be seen
absorption profile for each sample showing that formationof metal nanoparticle. However, SPR profile ofsynthesized nanoparticles by Ag-Ni and Ni-Ag irradiation
are clearly different, despite implanting the same doses of       

1 Introduction
Nano size materials have attracted tremendous attention
due to their unique properties, such as luminescence,absorption, magnetic property, catalytic activity andhydrogen absorption. These properties come from theirsize, shape, alloy system and complex electronic state
which is not appear in bulk materials. Metal ions
implantation into solid is one of a method to synthesis ofnanostructured material this is highly controlled impurity
injection with high density of energy into solid. In somecases, metal nanoparticles are formed in silica glass
without annealing by ion implantation. We suppose thismethod is useful to synthesize the new functional
nanomaterials with control of alloy structures and phases.
So far, we have successfully synthesized new functional
nanoparticles in glassy solid by using this method [1,2]. In
this study, amorphous SiO2 was alternately irradiated with
Ni and Ag ions at room temperature to investigate theeffects of multi-ion irradiation and changing theirirradiation order on the formation of nanoparticles in solid.
We found that it is possible to form metal nano-composite
and also the irradiation sequence affects the formation ofAg-Ni metal nano-composite. In this report, we will
discuss the structure of nanoparticles synthesized by Agand Ni ions irradiation in SiO2.

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Fig. 1 UV-vis spectra of Ag and Ni ions irradiated SiO2
glass samples.

surfaceFig. 2 STEM image of metal nanoparticles in SiO2
fabricated by Ni-Ag irradiation sequence.

Photon Factory Activity Report 2022 #40 (2023)

e(a)NiAg(b)

NiAg

50 nm

Fig. 2.5 TEM-EDX
STEM-EDX
elementalimagesof2Fig.
observationof analysis
nanoparticles
in SiO
nanoparticle
in SiO2 by (a) Ni-Ag and (b) Ag-Ni
synthesized
by formed
ion implantation.
irradiation sequence.
Fig. 3 STEM image of metal nanoparticles in SiO2
fabricated by Ag-Ni irradiation sequence.

Ag + Ni ions irrad.
Ni + Ag ions irrad.
Ni ion irrad.

AgNiNiAg

Binding Energy (eV)Fig. 4 XPS spectra of nanoparticles with respect tobinding energies of Ag and Ni atoms of nanocomposites in SiO2 formed by Ag and Ni ionsirradiation.
Ag and Ni. This indicates that the structure and electronicstates of the formed nanostructures are different. It is clear
from XRD results that a structure is formed in the glass,and a structure with an fcc structure has been confirmed inboth irradiation sequence.
Figs. 2 and 3 show STEM images of fabricated metal
nanoparticles in SiO2 with different irradiation order. In
both cases, the mean depth of fabricated nanoparticles
almost the same, about 170 nm from the surface. This value
well agrees with the result of the maximum depth of ion
deposition calculated by TRIM code. However, the Ni-Ag
distribution has a more localized formation depth ofnanoparticles than the Ag-Ni distribution. Moreover,although the average diameters of nanoparticles under AgNi irradiation is slightly smaller than that of Ni-Ag, the size
distribution is also distinctly different. Therefore, it can beseen that the order of irradiation has an effect on thediffusion of implanted atoms.
Figs. 4 shows the XPS spectra of fabricatednanoparticles by Ag-Ni and Ni-Ag irradiation. The peaks
corresponding to Ag and Ni can be observed in the XPS
spectrum, respectively. This result suggests that atoms ofeither element of Ag and Ni contribute to the formation ofthese nanostructures with metallic bonds. However, theintensity is different, and the atom implanted by irradiation
first shows a stronger intensity. This result also shows thealloy structure is not same for these nanoparticles. Formed

Fig. 6 EXAFS-FT spectra of the Ni absorption edge ofSiO2 irradiated with Ag and Ni ions in reverse order, andthat of SiO2 irradiated only with Ni ions for comparison.
nanoparticles were elemental analyzed by STEM-EDX
mapping imaged depicted as in figure 5. As shown in thesefigures, Ni-Ag irradiation forms composite nanoparticles
with core-shell-like discrete structure, while Ag-Ni
irradiation forms mixed alloys or composites ofhomogeneously assembled small pure metal clusters. Fig.
6 shows that the EXAFS spectra of Ag-Ni and Ni-Ag
irradiated SiO2. In this figure, it can be seen that the Ni-Nibond peak does not change, but their intensities are slightlydifferent. This indicates that although the crystal structureis the same, there is a difference in the ratio of bonding
species of Ni atoms in the particles, that is the solubility of
Ni and Ag atoms. Thus, it was found that the order ofirradiation has a great influence on the formation ofnanostructures consist of implanted ions by irradiation ofmultiple metal ions into a glass solid. One of the reasonsfor the formation of different aggregates is thought to be
the difference in the diffusion coefficient of each ion
species within the glass solid.
Acknowledgements
The authors thank the technical staff of TIARA facility
at QST-Takasaki. They also thank Drs. N. Usami, Y.
Okamoto and Y. Baba for their kind help.
References[1] T. Yamada et al., Nanotechnology 31, 455706 (2020).
[2] T. Yamada et al., Trans. Mater. Res. Soc. Jpn. 45, 127 (2020).
* horif@omu.ac.jp