**2.3 Ion beam-induced morphological changes in Ni nanowires**

The TEM micrograph before H<sup>+</sup> ions implantation of Ni-NWs is presented in **Figure 3(a)**. The Ni-NWs showed minor melting on the surface of the nanowires. After implantation with 2.75 MeV H+ ions at fluence of 1 × 1016 ions/cm2 , Ni-NWs diffused to each other at junction points and seen in **Figure 3(b)**. The interconnections of Ni-NWs after H+ ions beam irradiation are clearly shown by the TEM analysis. The reason for the interconnections between Ni-NWs might be heat induced due to H+ ions beam irradiation, which leads to melt and fusing of Ni-NWs into each other at intersecting positions [13, 14].

**Figure 2.** *(a) Un-implanted Cu-NWs, (b) 10 MeV Cu ions at 5 × 1015 ions/cm2 , and (c) 1 × 1016 ions/cm2 fluence.*

**7**

**3. Discussion**

*(a) TEM image of Ni-NWs before H+*

*irradiation at a dose 1 × 1016 ions/cm2*

**Figure 3.**

effect induced by ions beam irradiation.

was also observed after the interaction of H+

*.*

The morphological changes of MNWs such as the reduction in the diameter of nanowires after ion beam implantation, slicing and cutting metal nanowires might be heat induced owing to the ions beam implantation along the track of ions which leads to the melt and fuse of MNWs into each other at intersecting positions [13, 14]. As mentioned above, the connection of metal nanowires might be because of localize heat induced due to interaction of ions with MNWs or due to accumulation of atoms sputtered from MNWs lattices due to collision cascade

 *irradiation, and (b) TEM images of interconnected Ni-NWs after* 

In our previous reports, a similar mechanism of the interconnection of MNWs

the interaction of ions with MNWs may be of two types: I-Columbic interaction in which energetic ions interact with electrons in the atoms of material or II-elastic interaction in which energetic ion strikes with nuclei of atoms in the material. If the collision between incident energetic ion and atom in the material would be of the elastic type, then an atom would be sputtered out from the lattice and lead to a secondary collision with another atom in the lattice. In this manner, the collision cascade effect would result in the ejection of atoms from NWs lattices. Usually, in case of low energy ions, the dominancy of the sputtering phenomenon would result in the accumulation of sputtered atoms on intersecting positions and lead to the interconnection between them. In the case of Columbic interaction, the generation

ions with Ag-NWs [13, 14]. In general,

*Ion Implantation in Metal Nanowires*

*DOI: http://dx.doi.org/10.5772/intechopen.92328*

### **Figure 3.**

*Ion Beam Techniques and Applications*

**Figure 1(c**, **d)**, respectively [30].

NWs are cut, as shown in **Figure 2(c)**.

The TEM micrograph before H<sup>+</sup>

After implantation with 2.75 MeV H+

into each other at intersecting positions [13, 14].

*(a) Un-implanted Cu-NWs, (b) 10 MeV Cu ions at 5 × 1015 ions/cm2*

nections of Ni-NWs after H+

induced due to H+

of 1 × 1016 ions/cm2

implantation at the dose of 5 × 1014 ions/cm2

points, as shown in **Figure 1(b)** [30]. At high ion dose of 1 × 1016 ions/cm2

**2.2 Ion beam-induced morphological changes in copper nanowires**

**2.3 Ion beam-induced morphological changes in Ni nanowires**

start to be sliced, i.e., reduce the diameter and finally cut the nanowires as shown in

The un-implanted Cu-NWs image is presented in **Figure 2(a)**, shows a longshaped Cu-NWs. The diameters of un-irradiated Cu-NWs ranged from 100 to 150 nm. After 10 MeV Cu ions implantation at the dose of 5 × 1015 ions/cm2

Cu-NWs diffused at the junction points, as shown in **Figure 2(b)**. At high ion dose

**Figure 3(a)**. The Ni-NWs showed minor melting on the surface of the nanowires.

diffused to each other at junction points and seen in **Figure 3(b)**. The intercon-

analysis. The reason for the interconnections between Ni-NWs might be heat

, Cu-NWs start to be sliced, i.e., reduce the diameter and finally

ions implantation of Ni-NWs is presented in

*, and (c) 1 × 1016 ions/cm2*

 *fluence.*

ions at fluence of 1 × 1016 ions/cm2

ions beam irradiation are clearly shown by the TEM

ions beam irradiation, which leads to melt and fusing of Ni-NWs

, Ag-NWs diffused at the junction

, Ag-NWs

,

, Ni-NWs

**6**

**Figure 2.**

*(a) TEM image of Ni-NWs before H+ irradiation, and (b) TEM images of interconnected Ni-NWs after irradiation at a dose 1 × 1016 ions/cm2 .*

### **3. Discussion**

The morphological changes of MNWs such as the reduction in the diameter of nanowires after ion beam implantation, slicing and cutting metal nanowires might be heat induced owing to the ions beam implantation along the track of ions which leads to the melt and fuse of MNWs into each other at intersecting positions [13, 14]. As mentioned above, the connection of metal nanowires might be because of localize heat induced due to interaction of ions with MNWs or due to accumulation of atoms sputtered from MNWs lattices due to collision cascade effect induced by ions beam irradiation.

In our previous reports, a similar mechanism of the interconnection of MNWs was also observed after the interaction of H+ ions with Ag-NWs [13, 14]. In general, the interaction of ions with MNWs may be of two types: I-Columbic interaction in which energetic ions interact with electrons in the atoms of material or II-elastic interaction in which energetic ion strikes with nuclei of atoms in the material. If the collision between incident energetic ion and atom in the material would be of the elastic type, then an atom would be sputtered out from the lattice and lead to a secondary collision with another atom in the lattice. In this manner, the collision cascade effect would result in the ejection of atoms from NWs lattices. Usually, in case of low energy ions, the dominancy of the sputtering phenomenon would result in the accumulation of sputtered atoms on intersecting positions and lead to the interconnection between them. In the case of Columbic interaction, the generation

of localized heat leads to the diffusion of atoms on the intersecting positions, which would result in the welding or joining of the intersecting positions.

In the case of metals, the produced heat due to the ionization and increase in the temperature of the metal are all absorbed. This increment in temperature would result in the melting of MNWs and eventually interconnection is obtained between the melted NWs on intersecting positions in a better way. If the beam energy incident ion is high in MeV range, then more chances of production of localized heat rather than collision cascade effect will be observed and if the beam energy is low in keV range then the sputtering phenomenon would be dominant [14].

### **3.1 Ion beam-induced structural changes in silver nanowires**

XRD measurements taken at room temperature were used to study the structural changes in pristine and Ag-NWs as shown in **Figure 4**.

The diffraction pattern of the pristine sample shows peaks at 2θ angles of 38.6° and 44.11o , which corresponds to (111) and (200) planes of face-centered cubic Ag-NW. However, when XRD patterns of C ion irradiated Ag-NWs were compared with the pristine XRD pattern, it revealed a slight shifting of 2θ positions of diffraction peaks. This shifting in the 2θ position might be due to strain, which is often produced from surface defects, grain boundaries, dislocations, etc. Moreover, it can be observed from **Figure 4** that XRD peak intensities decrease with an increase in ion beam fluence. This decrease in XRD peak intensities might be due to the production of irradiation-induced defects such as point defects, dislocations, and grain boundaries, which accumulated to form defect clusters and led to the formation of a few pockets of amorphous zones. The crystal quality of material degrades due to the presence of these amorphous zones [30].

### **3.2 Ion beam-induced structural changes in Cu nanowires**

Structural changes by ion implantation in Cu-NWs were studied using the XRD technique. In this study, Cu-NWs were irradiated with 100 keV H<sup>+</sup> beam at

**Figure 4.** *XRD spectra of (a) un-implanted Ag-NWs, (b) 5 MeV C ions at the dose of (c) 2 × 1015 ions/cm2*

*.*

**9**

**Figure 6.**

**Figure 5.**

*Ion Implantation in Metal Nanowires*

*DOI: http://dx.doi.org/10.5772/intechopen.92328*

different fluence from 1 × 1015ions/cm2

to 5 × 1016 ions/cm2

XRD technique and compared with the un-irradiated spectrum. **Figure 5** shows the XRD spectra of samples irradiated at different fluences. **Figure 5(a)** shows the XRD spectrum of un-irradiated Cu-NWs. The XRD spectrum comprised of one (111) peak at 2*θ* = 44.2°, which is the preferred crystal plan of Cu-NWs. The other two low intensities peaks at 2*θ* = 52.4° and 73.9° are corresponding to the

*XRD spectra of Cu-NWs (a) Un-implanted; (b-d) implanted with 100 keV H+*

*XRD patterns of Ni-NWs (a) before irradiation and (b) irradiated with H+*

, Cu-NWs was done by

 *ions at different doses.*

 *ions at fluence 1 × 1016 ions/cm2*

*.*

### *Ion Implantation in Metal Nanowires DOI: http://dx.doi.org/10.5772/intechopen.92328*

*Ion Beam Techniques and Applications*

and 44.11o

of localized heat leads to the diffusion of atoms on the intersecting positions, which

In the case of metals, the produced heat due to the ionization and increase in the temperature of the metal are all absorbed. This increment in temperature would result in the melting of MNWs and eventually interconnection is obtained between the melted NWs on intersecting positions in a better way. If the beam energy incident ion is high in MeV range, then more chances of production of localized heat rather than collision cascade effect will be observed and if the beam energy is low in

XRD measurements taken at room temperature were used to study the structural

, which corresponds to (111) and (200) planes of face-centered cubic Ag-NW. However, when XRD patterns of C ion irradiated Ag-NWs were compared with the pristine XRD pattern, it revealed a slight shifting of 2θ positions of diffraction peaks. This shifting in the 2θ position might be due to strain, which is often produced from surface defects, grain boundaries, dislocations, etc. Moreover, it can be observed from **Figure 4** that XRD peak intensities decrease with an increase in ion beam fluence. This decrease in XRD peak intensities might be due to the production of irradiation-induced defects such as point defects, dislocations, and grain boundaries, which accumulated to form defect clusters and led to the formation of a few pockets of amorphous zones. The crystal quality of material degrades due to the

The diffraction pattern of the pristine sample shows peaks at 2θ angles of 38.6°

Structural changes by ion implantation in Cu-NWs were studied using the

beam at

*.*

XRD technique. In this study, Cu-NWs were irradiated with 100 keV H<sup>+</sup>

*XRD spectra of (a) un-implanted Ag-NWs, (b) 5 MeV C ions at the dose of (c) 2 × 1015 ions/cm2*

would result in the welding or joining of the intersecting positions.

keV range then the sputtering phenomenon would be dominant [14].

**3.1 Ion beam-induced structural changes in silver nanowires**

**3.2 Ion beam-induced structural changes in Cu nanowires**

changes in pristine and Ag-NWs as shown in **Figure 4**.

presence of these amorphous zones [30].

**8**

**Figure 4.**

different fluence from 1 × 1015ions/cm2 to 5 × 1016 ions/cm2 , Cu-NWs was done by XRD technique and compared with the un-irradiated spectrum. **Figure 5** shows the XRD spectra of samples irradiated at different fluences. **Figure 5(a)** shows the XRD spectrum of un-irradiated Cu-NWs. The XRD spectrum comprised of one (111) peak at 2*θ* = 44.2°, which is the preferred crystal plan of Cu-NWs. The other two low intensities peaks at 2*θ* = 52.4° and 73.9° are corresponding to the

**Figure 5.** *XRD spectra of Cu-NWs (a) Un-implanted; (b-d) implanted with 100 keV H+ ions at different doses.*

**Figure 6.** *XRD patterns of Ni-NWs (a) before irradiation and (b) irradiated with H+ ions at fluence 1 × 1016 ions/cm2*

*.*

crystal planes (200) and (220), respectively. These peaks and intensities showed that Cu-NWs had a polycrystalline structure. XRD results are confirmed with the HRTEM images as shown in **Figure 5(a)**. While if we observe XRD patterns of proton irradiated Cu-NWs, some new peaks appeared at low angle positions (see **Figure 5(b–d)**). These new peaks are of Cu2O, showing that Cu nanowires might be oxidized due to oxygen atoms trapped into proton irradiation-induced defect sites in nanowire lattices.

These defects sites were observed by HRTEM study of ion irradiated in Cu-NWs. It was observed that at low ion irradiation, few point defects were created as the ion fluence increases, these point defects agglomerate to form large amorphous zones. These defects and amorphous zones give a path to O atom to form the Cu2O phase in Cu-NWs.
