keV Argon Ions Research Articles

Effect of deformation nanostructuring on ion-beam erosion of metals

The effect of deformation nanostructuring of copper, nickel, and titanium on ion-induced morphology and sputtering under 30 keV argon ions high-fluence irradiation along the normal to the surface has been studied. Sputtering of a layer commensurate with the size of metal grains leads to a uniform cone-shaped relief, the stationary erosion of which occurs with significant redepositing of atoms.

Improved ammonia gas adsorption of surface engineered WS2 nanoflakes

Recent investigations into nanostructured WS2 have shown promising results in the detection of reducing gases, such as ammonia. However, this material faces limitations with respect to the vital parameters such as sensitivity, recovery, and repeatability over an extended period in its purest form. To address these challenges, a low-energy (5 keV) argon ion beam was used to irradiate nanostructured WS2 nanoflakes at various fluences, leading to observable morphological and structural changes. The irradiation of WS2 resulted in a significant enhancement in its ability to detect ammonia gas. The sensing response saw a threefold increase, and both the response and recovery times were reduced significantly compared to pristine samples. Ion beam irradiation changes the overall morphology of nanoflakes and induces a certain degree of defects as apparent from electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy studies. The ion-solid interaction simulation predicts a larger amount of sulfur vacancy than tungsten due to irradiation, which is also supported by experimental results. Density functional theory predicts that sulfur vacancy leads a decisive role in better adsorption of ammonia than the pristine surface. The NH3 molecule orients towards the defective surface leading to a higher charge transfer from the NH3 molecule to the surface than the pristine surface along with a smaller adsorption height.

Ion Implantation‐Induced Bandgap Modifications in the ALD TiO2 Thin Films

Atomic layer deposited (ALD) TiO2 layers are implanted with N, O, and Ar ions to reduce the bandgap, thereby increasing its absorbance in the visible region. The implantation is accomplished with 40 keV nitrogen, 45 keV oxygen, and 110 keV argon ions in the fluence range 1 × 1015 to 5.6 × 1016 ions cm−2. The energy of each incident ion is tuned using stopping and range of ions in matter (SRIM) to produce defects around the same projected range. The structural analysis of the as‐deposited film is performed through X‐ray diffraction (XRD), scanning electron microscopy (SEM), Rutherford backscattering (RBS), and time of flight elastic recoil detection analysis (ToF‐ERDA). The implanted layers are characterized using diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR) to study the optical and vibrational properties of the films. The results demonstrate that nitrogen implantation in TiO2 reduces the reflectance from 43.52% to 26.31% and bandgap from 2.68 to 2.61 eV, making it a promising bandgap‐engineered material for capping layers in solar cell applications. The refractive index of the 40 keV nitrogen ion implanted film at 1 × 1016 ions cm−2 (N‐16) increases from ≈2.8 to ≈2.95. OPAL2 solar cell simulations show that the N‐16 implanted TiO2 anti‐reflective coatings (ARC) can enhance the absorbed photocurrent by 7.3%.

Augmented ammonia sensing of ion-beam modified MoSe2

Gas sensors based on nanostructured transition metal dichalcogenides, such as MoSe2, are increasingly becoming important due to their low band gap, good electrical conductivity and selectivity. However, some of the parameters related to the gas adsorption can be tuned to enhance the overall sensing performance. The change of response sometimes remains low because of small number of active interaction sites on the surface. There are challenges related to slow response and slow recovery of the sensor. Furthermore, if the surface is hydrophilic, it can attract moisture, which may reduce interactions with the target gas and may also reduce the lifetime of the sensor. In this study we have used ion irradiation technique to overcome these challenges and exploit theoretical models to explain the physics behind enhanced sensing performance of 3D nanostructured MoSe2. A low energy (5 keV) argon ions have been used to induce structural and morphological modification of MoSe2. The irradiation leads to formation of Mo and Se vacancies, which is predicted by ion-solid interaction simulation and corroborated with various characterization techniques. The surface becomes superhydrophobic after irradiation and a significant increase of electrical conductivity takes place. We found that the ammonia sensing response increases by about 60 % due to the irradiation. There are further significant gains of response and recovery time of the sensor, post-irradiation. The response of irradiated samples shows more stability as compared to the pristine sample over a period of 180 days. First principles-based calculation points out that the charge transfer happens from surface to ammonia during the interaction and ion irradiation induced vacancies lead to better adsorption of ammonia in case of irradiated sample than that of the pristine sample.

Effect of deformation nanostructuring on ion-beam erosion of copper

The effect of deformation nanostructuring on ion-beam erosion of copper at high fluences of irradiation with 30 keV argon ions was experimentally studied. Deformation nanostructuring by high-pressure torsion was used to form an ultrafine grained structure with a grain size of ~0.4 µm in copper samples with an initial grain size about 2 µm. It was found that when a layer of thickness comparable to the grain size was sputtered, a steady-state cone-shaped relief was formed on the copper surface, the appearance of which did not change with increasing irradiation fluence. It has been shown that the smaller the grain size in copper, the greater the concentration and the smaller the cone height on the surface. The cone inclination angles, close to 82°, as well as the sputtering yield of 9.6 at./ion, practically does not depend on the copper grain size, the thickness of the sputtered layer, and the irradiation fluence. Calculations using the SRIM code showed that when taking into account the sputtering of atoms from the walls of the cones, the sputtering yield of a cone-shaped copper relief Үc, was 3.5 times less than the yield of a single cone, 1.2 times greater than the sputtering yield of a smooth surface, and the value of 9.25 at./ion was close to the experimentally measured one.

Molecular dynamics simulation of 100 keV argon ion radiation effects in metals and comparison with stopping and range of ions in matter code

Simulation is essential to analyse radiation-induced effects because energetic ions have short transit times within materials (Ar ions of 1 keV and 100 keV have transit times of 0.29 picoseconds and 29 femtoseconds respectively, through a 25 nm Al film). The binary collision approximation (BCA) is extensively used in simulations to study damage caused by energetic ions due to its computational efficiency. Stopping and Range of Ions in Matter (SRIM), a widely used Monte Carlo software using BCA, provides accurate ion ranges consistent with experiments. Molecular dynamics simulations are powerful computational method, where classical equations of motion are solved to track atomic movements from radiation damage, but computational resources required are heavier for this method. In our current effort, the energy transfer from 100 keV Ar+ to metal targets is analysed as a function of target properties, including melting temperature and atomic density, using these two methodologies. A detailed investigation of 100 keV Ar+ ion impact on metal targets is done using the classical Molecular Dynamics simulation program ‘MDRange’, which uses the Recoil Interaction Analysis (RIA) approximation, where the interaction between the ion and its closest neighbours is considered via a two-body potential. The correlation of energy transferred to the metal with the target properties is examined considering the physical approximations of each technique.

380-keV Ar+-irradiation effects on optical phonons in graphite studied with transient reflection measurement

In this work, we performed transient reflection measurements using the pump–probe protocol to investigate the influence of lattice defects induced by 380 keV argon (Ar) ions on the phonon dynamics of interlayer shearing (E2g1) and in-plane carbon stretching (E2g2) modes in highly oriented pyrolytic graphite (HOPG). The frequency and decay rate of E2g1- and E2g2-mode phonons were changed significantly at the fluence of 1×1014 ions/cm2. This indicated that significant structural changes in HOPG due to 380 keV Ar-ion irradiation were expressed as changes in the frequency and decay rate of phonons. In HOPG irradiated with 380 keV Ar+ at the fluence of 1×1014 ions/cm2, our measurement results indicated that compressive and tensile stresses contributed to in-plane and interlayer graphite structures, respectively.

Secondary ion mass spectrometry analysis of metal oxides using 70 keV argon, carbon dioxide, and water gas cluster ion beams

Manganese (II) oxide (MnO), manganese (IV) oxide (MnO2), cobalt (II,III) oxide (Co3O4), and nickel (II) oxide (NiO) were analyzed with time-of-flight secondary ion mass spectrometry using 70 keV gas cluster ion beams. The obtained mass spectra are influenced by projectile chemistry and to a lesser extent velocity. Gas cluster ion beams containing CO2 or H2O enhanced the relative yield of metal oxide and metal hydroxide secondary ions compared to beams containing only Ar. For all gas cluster ion beams tested, steady-state ion ratios [MxOy]+/[Mx]+ were reached. For manganese oxides, the [MnxOy]+/[Mnx]+ ratio reflected the metal oxidation state whereas the [MnxOyHz]+/[Mnx]+ ion ratios did not. This study demonstrates that secondary ion mass spectrometry using 70 keV gas cluster ion beams provides a novel approach to the quantitative analysis of the surface and subsurface regions of metal oxides related to energy-storage materials.

From orthophosphate to phosphine‐based groups: The effects of argon ion sputtering on doped polyethersulfone films

Pyridine‐containing polyethersulfone films are being studied extensively as they are considered promising types of polymer electrolyte membranes to be used in high‐temperature fuel cell (HT‐PEMFC) applications. In this study, modified polyethersulfone films doped with phosphoric acid were bombarded by a 3 keV argon ion beam resulting in a different chemical environment at the end of the sputtering process. X ray Photoelectron spectroscopy (XPS) was employed to analyze the changes that occurred due to the exposure to the beam, confirming that distinct species appeared and indicating that reactions between the acid and the film occurred. These changes cause the formation of new phosphine‐based structures and point out the impact of ions as a crucial factor in the degradation of doped polyethersulfone films.

Defect-Engineered 3D Nanostructured MoS2 for Detection of Ammonia Gas at Room Temperature

Recent studies on nanostructured MoS2 show promising performance in the detection of reducing gases like ammonia (NH3). However, this material in the pristine form possesses limitations in terms of response, recovery, and repeatability over a long duration of time. Several attempts have been made to overcome these shortcomings by modifying it chemically to make a hybrid form or direct doping with other atoms. In this work, we demonstrate that suitable defect engineering of 3D nanostructured MoS2 induced by a low energy ion beam can lead to a significantly improved performance of sensing NH3 compared to the as-prepared one. Significant decreases in response and recovery times have been demonstrated at room temperature for the modified MoS2 compared to its pristine form, which shows its best response only at a higher temperature of about 200 °C. A 3D nanoflower-like structure of MoS2 was synthesized hydrothermally, which was coated on substrates, and then irradiated with 5 keV argon ions at different doses. While the ion beam-induced morphological modifications are observed via electron microscopic study, the surface defects are apparent in X-ray diffraction, Raman scattering, and X-ray spectroscopic studies. The ion beam-modified MoS2 shows a higher electrical conductivity and water-repelling nature compared to the pristine one, which are complementary properties for better sensing performance. While Monte Carlo-based 3D ion-solid interaction simulation was used to support the morphological modifications and defect developments after ion irradiation, the sensing mechanism and change in conductivity were successfully explained using density functional theory-based simulations.

Evaluation of argon ion impact parameters in aluminium oxide by means of SRIM program and investigation of the effect of argon ion implantation on the thermoluminescence properties aluminium oxide

The thermoluminescence properties of aluminium oxide (alumina) implanted with 80 keV argon ions at fluences in the range of were investigated. The unimplanted and implanted samples were irradiated at a dose of 40 Gy and heated at a rate of 1°C/s. The glow curve of unimplanted and implanted samples shows 5 distinct peaks; the main dosimetric peak and four other peaks of lower intensity. In this study, our analysis has focussed on the main dosimetric peak located at 180°C, 191°C, 177°C, 208°C, 219°C and 207°C for the unimplanted sample and implanted samples respectively. It was observed that the TL intensity decreases with fluence of implantation. This suggests that ion implantation decreases the concentration of electron traps responsible for thermoluminescence. It can also be suggested that competition effects involving radiative pathways and non-radiative competitor traps may lead to a low thermoluminescence signal in the implanted samples in comparison to the unimplanted thermoluminescence signal. These competitive processes will tend to favour first-order kinetics, and consequently lead to a strong stability of the glow curve shapes. The creation of defect clusters as well as extended defects could also be responsible for the reduction in TL signal. The stopping and range of atoms in matter (SRIM) was used to evaluate the ion impact parameters including ion range, vacancy distribution and energy loss in Al2O3. Subsequent to ion implantation, it was found that the number of oxygen vacancies which are related to electron traps are higher than the number of aluminium vacancies. Kinetic analysis was carried out by means of the initial rise, Chen’s peak shape, various heating rate, the whole glow curve, glow curve fitting and isothermal decay methods. The activation energy was found to be around and the frequency factor to be of the order regardless of the implantation fluence. The dosimetric features of samples were also investigated at doses in the range of 40–200 Gy. Samples generally showed a superlinear response at doses less than 140 Gy and sublinear response at doses higher than 160 Gy.

Comparative study on atomically heterogeneous surface with conical arrays of field emitters generated using plasma based low-energy ion beams

A comparative study of the field emission properties of conical arrays of atomically heterogeneous, self-organized, micro–submicro–nanodimensional structures, irradiated at normal incidence by high flux of 2 keV argon (flux=6.47×1015cm−2s−1) and krypton ions (flux=4.81×1015cm−2s−1) on copper substrates, without employing any external seeding, is presented. The variation in surface structural growths with ion beam fluence is investigated using scanning electron, atomic force, and transmission electron microscopy. The exposed surfaces are atomically heterogeneous due to the presence of embedded argon and krypton ions in the interstitial layers (≈nm) as observed from the x-ray photoelectron spectroscopy analysis. Kelvin probe force microscopy is employed to analyze the variation in local work function caused by surface deformities and implantation of inert gaseous ions. The conical arrays are naturally selected field emitter sources, and their field enhancement factor is calculated from the Fowler–Nordheim equations. The argon ion treated substrate at a fluence of 4.85×1018cm−2 gives rise to uniformly distributed structures and has a low turn-on voltage of 2.76 kV with an electron emission current of 0.58 nA. Among the krypton ion irradiated substrates, the sample irradiated at the highest fluence of 5.12×1018cm−2 produces self-organized conical arrays having uniform dimension, orientation, distribution, and even a higher electron emission current of 0.81 nA with a lower turn-on voltage of 2.12 kV. Thus, it may be concluded that krypton ion irradiation provides better generation of naturally selected arrays of field emitters.

Формирование субмикронной конусообразной морфологии поверхности при ионно-лучевом распылении наноструктурного никеля

The results of a research on the surface morphology of nanostructured nickel after high-fluence irradiation with 30 keV argon ions have been presented. The nanostructure in nickel was formed by high-pressure torsion deformation. It has been shown that nanostructuring deformation of nickel by ion-beam sputtering allows to receive a uniformly coated surface with submicron cones. The thermal stability of the obtained cone-like structure on nanostructured nickel has been determined.

Formation of submicron cone-shaped surface morphology under ion-beam sputtering of nanostructured nickel

The results of a research on the surface morphology of nanostructured nickel after high-fluence irradiation with 30 keV argon ions have been presented. The nanostructure in nickel was formed by high-pressure torsion deformation. It has been shown that deformation nanostructuring of nickel and subsequent ion-beam sputtering allows receiving a surface uniformly coated with submicron cones. The thermal stability of the obtained cone-shaped structure on nanostructured nickel has been determined. Keywords: nanostructure, high-pressure torsion, ion irradiation, cones, thermal stability.

Structural changes induced in graphene oxide film by low energy ion beam irradiation

Graphene oxide consists of sp3 hybridization due to the presence of different oxygen containing functional groups on its edges and basal planes. However, its sp3/sp2 hybridization can be tuned by various methods. Ion beam irradiation can also be one of the methods to optimize sp2/sp3 hybridization for its desirable properties. In this work, graphene oxide films were irradiated with 100 keV Argon ions at different fluences varying from 1013 to 1016 ions/cm2. Synchrotron X-ray diffraction (XRD) measurements showed an increase in crystallinity at low fluence of 1013 ions/cm2. Raman spectroscopy qualitatively determines the defects induced by ion beam in graphene oxide. Also, identification of different groups and their removal at different ion fluences was done using Fourier transform infra-red spectroscopy technique.

Morphological and mechanical evolution of nanostructured ZrN thin films under 165 keV argon ions irradiation

Zirconium nitride is a promising candidate ceramic material to be adopted as an inert matrix for transuranic fuel, a new fuel concept having as targets the closing of the nuclear fuel cycle, and reduce the environmental impact of nuclear waste. Nevertheless, the comprehension of radiation tolerance of zirconium nitride still limited. In this paper, we have studied the radiation stability of nanostructured zirconium nitride (ZrN) thin films using 165 keV argon-ions (Ar2+) irradiation at room temperature. After irradiation, the microstructural, morphological and mechanical properties of the irradiated ZrN films were investigated and compared to an un-irradiated reference film. The grazing incidence X-ray diffraction tests (GI-XRD) revealed a (100) ZrN textured films, the atomic force microscope (AFM) and the scanning electron microscope (SEM) images showed that the as-deposited ZrN films were nano-crystalline with spherical grains of about 50 nm in size and rms surface roughness of about 1.175 nm. After irradiation, the estimate grains size was found to increase to 72 and 86 nm for films irradiated to 2.3 and 22.3 (dpa) respectively, indicating grains coalescence. The nano-hardness of the irradiated films compared to the un-irradiated film was decreased for both doses, while the XRD patterns demonstrate a crystalline ZrN even at the higher dose of 22.3 (dpa), suggesting along with AFM and SEM results grain growth without amorphisation.

Effect of ion irradiation on structural state and mechanical properties of naturally-aged hot-pressed D16 (Al-Cu-Mg) alloy profiles

The effect of irradiation with 20 keV argon ions on the mechanical properties, structure, and phase composition of quenched and then naturally aged, hot-pressed profiles (6 mm thick) from the D16 alloy of the Al-Cu-Mg system has been studied. It was found that short-term irradiation with Ar+ ions (E = 20 keV, j = 200 μA/cm2, F = 1×1016 cm-2, irradiation time 8 s) leads to transformation of the microstructure and phase composition of the alloy. The coarsening of the initial subgrain structure occurs near the sample surface. Both in the surface layer and at a distance of ∼ 150 μm from it, partial dissolution and fragmentation of complex intermetallic compounds of crystallization origin located along grain boundaries are observed, as well as a decrease in the size and change in the morphology of Al6(Fe, Mn) intermetallic compounds of crystallization origin are observed too: the distribution density of lamellar precipitations decreases, and equiaxial precipitations disappear. Under the influence of irradiation, the decomposition of the supersaturated solid solution is activated with the formation of a more stable phase S’. As a result of ion-beam treatment in this mode, the plasticity of the alloy increases while maintaining the strength properties.

Impact of argon ion implantation on CdS nanorod mesh

Ion implantation is explored as potent approach for tuning the optoelectrical properties of semiconducting thin films via controlled defect engineering. This present study investigates the 180 keV argon (Ar+) ion implantation on the cadmium sulfide (CdS) nanorod mesh; synthesized via chemical bath deposition (CBD) method. X-ray diffraction (XRD) analysis supports the consistency of hexagonal phase even after implantation, but variation in the intensity of diffraction planes is noted. Field emission scanning electron microscopy (FESEM) scans are recorded to examine the implantation effect on the surface morphology. Implantation induces lattice disorder that resulted decrease in band gap energy from 2.39 eV to 2.08 eV and the corresponding green-yellow-red emission bands are discussed in photoluminescence (PL) spectra.

Microconical Structure Formation and Field Emission From Atomically Heterogeneous Surfaces Created by Microwave Plasma–Based Low-Energy Ion Beams

We report the formation of self-organized microconical arrays on copper surface when exposed to high flux (5.4 × 1015 cm−2 s−1) of 2 keV argon ion beams at normal incidence. The created microconical arrays are explored for field emission properties. The surface morphologies are investigated by scanning electron microscopy and atomic force microscopy. The local work function variation is analyzed by Kelvin probe force microscopy, and the argon content in the irradiated layer is measured with X-ray Photoelectron Spectroscopy. The average aspect ratio (base width/height) of microstructures for individual irradiated samples is found to increase from 0.7 to 1.5 with a decrease in ion fluence. The ion concentration is highest (3.89 %) for a fluence of 4.7 × 1018 cm−2, which asserts the formation of atomically heterogeneous surface due to subsurface ion implantation. An enhancement in the field emission properties of the argon ion–treated copper substrates at a fluence of 4.7 × 1018 cm−2 with a low turn-on voltage of 2.33 kV and with electron emission current 0.5 nA has been observed. From the Fowler–Nordheim equations, the field enhancement factor is calculated to be 5,561 for pristine copper, which gets enhanced by a factor of 2–8 times for irradiated substrates. A parametric model is considered, by taking into account the modified local work function caused due to structural undulations of the microstructures and presence of implanted argon ions, for explaining the experimental results on the field enhancement factor and emission current.

Argon ion implanted CR-39 polymer: Optical and structural characterization

The samples of Polyallyl diglycol Carbonate (CR-39) were implanted with 100 keV argon ions at fluences 1 × 1015, 5 × 1015 and 1 × 1016 ions/cm2 to be employed for optical and structural studies. The changes in transmittance, reflectance, optical energy gap and refractive index have been studied through the UV–Vis–NIR spectroscopic technique. The enhancement in reflectivity and a strong reduction in transmittance, particularly in the UV region, are observed after Ar+ implantation in CR-39 samples. The absorbance value remains low ~0.10, 0.15 and 0.20 in the key communication wavelength region i.e. 800–1600 nm for sample implanted at the fluence of 1 × 1015, 5 × 1015, 1 × 1016 Ar+/cm2, respectively. The Optical energy gap (EOPT) is determined to be 0.92 eV for the implanted layer of the sample implanted at the fluence of 1 × 1016 Ar+/cm2, whereas 3.70 eV for the pristine sample. The surface electrical conductivity is increased from ~1.49 × 10−14 S (pristine sample) to ~8.34 × 10−10 S for sample implanted at the fluence of 1 × 1016 Ar+/cm2. The formation of conjugated π-bond (-CC-) structure with Ar+ implantation is confirmed via FTIR and Raman measurements. TGA results are analysed in detail and are found to be in strong agreement with the changes observed in different properties of CR-39 after ion implantation.