Swift Heavy Ion Irradiation Research Articles

Metallic Ca Aggregates Formed Along Ion Tracks and Optical Anisotropy in CaF2 Crystals Irradiated with Swift Heavy Ions

It is known that swift heavy ion (SHI) irradiation induces the shape elongation of metal nanoparticles (NPs) embedded in transparent insulators, which results in anisotropic optical absorption. Here, we report another type of the optical anisotropy induced in CaF2 crystals without including intentionally embedded metal NPs. The CaF2 samples were irradiated with 200 MeV Xe14+ ions with an incident angle of 45° from the surface normal. With the increasing fluence, an absorption band at ~550 nm, which is ascribed to Ca aggregates, increases both the intensity and the anisotropy. XTEM observation clarified the formation of the continuous line structures and the discontinuous NP chains parallel to the SHI beam. Numerical simulations of the optical absorption spectra suggested the NP chains but not the continuous line structures as the origin of the anisotropy. The optical anisotropy in CaF2 irradiated with SHIs is different from the shape elongation of NPs.

Sub-nanoporous polyimide membrane with selective and fast K+ transport

Biological ion channels have excellent monovalent ion separation performance, and it is of great significance to develop artificial membrane materials with monovalent ion selectivity based on their mechanism. The latent-track method is a new technology to prepare sub-nanometer channels on polymer membranes by swift heavy ion irradiation. This method has been widely applied in the study of mono/divalent ion separation membranes, but its application in monovalent ion separation membranes still needs to be explored. In this work, polyimide (PI) film was irradiated by swift heavy ion, then water rinsed, and the sub-nanoporous PI membrane with effective channel size in the range of 0.30 and 0.66 nm was fabricated, then its electrical and transport properties were studied. Due to the smaller hydrated diameter and lower hydration energy of K+, the membrane exhibited good selectivity for K+. The selectivity ratio of K+/Li+ is 3.4–3.9, and the maximum K+ flux can reach 0.44 mol m−2 h−1 at 55℃. The sub-nanoporous PI membranes are expected to be applied in salt lake lithium extraction, fine processing of potassium and lithium, and other relevant scenarios.

Enhanced NO2 Gas Sensing in Nanocrystalline MoS2 via Swift Heavy Ion Irradiation: An Experimental and DFT Study.

Nanostructured transition metal dichalcogenides (TMDs) like MoS2 hold promise for gas sensing applications due to their exceptional properties. However, limitations exist in maximizing sensor performance, such as limited active sites for gas interaction and sluggish response/recovery times. This study explores swift heavy ion (SHI) irradiation as a strategy to address these challenges in MoS2-based NO2 gas sensors. MoS2 nanoflakes were fabricated and subsequently irradiated with 120 MeV silver (Ag) ions to induce structural and morphological modifications. Characterization techniques confirmed the formation of Mo and S vacancies within the MoS2 lattice due to irradiation. Significantly, SHI irradiation resulted in a remarkable enhancement of approximately 3 times improvement in sensing response compared to pristine MoS2 sensors. Additionally, the irradiated sensors exhibit substantial improvements in both response and recovery times for NO2 detection. SHI irradiation resulted in the formation of self-affine nanostructures and increased grain fragmentation as fluence rises. This enhanced surface area is hypothesized to promote gas-sensor response. To gain deeper insights into the underlying mechanism, first-principles calculations were employed. These calculations suggest that electron transfer occurs from the MoS2 surface to the NO2 molecule during interaction. Furthermore, the irradiation-induced vacancies facilitate stronger NO2 adsorption on the MoS2 surface compared to the pristine sample. This work demonstrates the effectiveness of SHI irradiation in engineering defects within MoS2 nanoflakes, leading to significantly improved NO2 gas-sensing performance. This approach offers a promising avenue for developing next-generation TMD-based gas sensors with enhanced sensitivity, response times, and stability.

Effect of stress and irradiation fluence on latent track formation in swift heavy ion irradiation: A case study on TiO2

Swift Heavy Ions (SHI) irradiation, characterized by high kinetic energy ions, induces significant material/structural modification, e.g., latent track. However, the intricate interaction among various physics, i.e., mechanical stress, phase transition, and heat transfer, has been ignored in the continuum-based approaches in favor of simplicity. Here, we developed a two-dimensional coupled phase-field inelastic-thermal spike (PF-iTS) model to investigate the effect of thermal cross-talk, elastic energy, and irradiation fluence on latent track formation and size. The results reveal a shift in the critical electronic stopping energy and a reduced track radius under mechanical stress. Additionally, the study demonstrates the impact of thermal cross-talk between incidents, i.e., simultaneous and delayed double ion impacts, showing potential track merging and variations in track morphology.

Swift heavy ions induced transformations in the structural and magnetic properties of Co/Pt multilayer thin films for magnetic storage applications

The integration of CoPt nanoparticles into an insulating matrix has garnered significant attention in material science, nanotechnology, and electronic engineering, particularly for their potential use in magnetic storage media. Precise control over the size, shape, and ordering of these nanoparticles is crucial. This study investigates the impact of swift heavy ion irradiation (120 MeV Ag+9) with varying ion fluences (1 × 1013 and 3 × 1013 ions/cm2) on the structural and magnetic properties of sputter-deposited Co/Pt multilayer thin films on quartz substrates. X-ray diffraction (XRD) analysis of the pristine samples reveals the presence of an FCC-structured CoPt alloy. In contrast, films irradiated with a fluence of 1 × 1013 ions/cm2 exhibit superlattice peaks (001) and (110), indicative of L10-structured CoPt alloy, whereas films subjected to 3 × 1013 ions/cm2 retain the FCC structure. This suggests that a fluence of 1 × 1013 ions/cm2 promotes ordering, while 3 × 1013 ions/cm2 induces disordering. Selected area electron diffraction (SAED) patterns from TEM confirm these structural transitions, while SQUID magnetometry reveals an increase in coercivity at 1 × 1013 ions/cm2, followed by a reduction at 3 × 1013 ions/cm2, consistent with the observed structural changes. These results demonstrate that carefully controlled ion fluences can effectively tailor the structural and magnetic properties of Co/Pt multilayers, enhancing their suitability for advanced magnetic storage applications.

Exfoliated layered nanosheets of orthorhombic SnS, subjected to 90 MeV carbon ion irradiation

Derived through liquid phase exfoliation, the irradiation response of nanoscale, exfoliated tin sulfide (SnS) systems are being reported in this work. The SnS nanosheets were exposed to 90[Formula: see text]MeV [Formula: see text] ion beams across fluences ranging from [Formula: see text] to [Formula: see text][Formula: see text]ions/cm2. With an electronic energy loss ([Formula: see text]) of [Formula: see text]56[Formula: see text]eV/Å, dominating over the nuclear energy loss ([Formula: see text]), the average crystallite size of the irradiated samples displayed an augment when compared to its pristine counterpart. Exhibiting an orthorhombic crystal structure, structural analyses of both pristine and irradiated samples were conducted via X-ray diffraction (XRD) technique. Raman analysis has manifested some modifications in the SnS nanosystem upon radiation exposure, particularly with higher fluences causing local structural disorder and amorphization of the material. Moreover, morphological changes in the irradiated SnS samples were examined using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), with AFM images revealing an increase in the root mean square (RMS) roughness corresponding to ion fluence. Furthermore, swift heavy ion (SHI) irradiation prompted a non-rectifying Ohmic [Formula: see text] characteristics and altered the electrical conductivity of the SnS nanosheets.

Formation of metallic/oxide composites of Sn from SnO2 thin films with swift heavy ion irradiation

Formation of metallic/oxide composites of Sn from SnO2 thin films with swift heavy ion irradiation

Computational insights from the thermal spike model into mesoporous silica behavior during swift heavy ion irradiation

Mesoporous silica materials are pivotal in various scientific domains due to their unique properties and versatile applications. However, understanding their response to irradiation, particularly from Swift Heavy Ions (SHI), remains limited. We address this gap by investigating experimental mesoporous silica behavior under 12 MeV Carbon and 92 MeV Xenon bombardment using the Three-Dimensional Thermal Spike Model (3DTS) simulation. Our computational simulations reveal localized heating effects and provide mechanistic insights into experimental observations, shedding light on pore closure and different observed damage patterns. This study is the first application of this model to porous silica and deepens our knowledge of the mechanism of structural evolution under ion bombardment.

Short-range order structural response of CdSe nanocrystals under 120 MeV swift heavy ions irradiation: A pair distribution function analysis

Swift heavy ion (SHI) irradiation deposits large amount of energy in the target material which thereby influences the structural features of the sample. In this work, the structural response of CdSe material has been studied under high energetic 120 MeV SHI irradiation. The long-range structural modifications of CdSe under SHI have been analyzed using Rietveld study. On the other hand, the short-range behavior of SHI irradiated CdSe has been studied using Pair distribution function (PDF), which can be interpreted as a distance map between two atoms in terms of a PDF peak. The small-box structural refinement of the samples has been performed using the PDFgui package for the study of modifications in the atomic arrangement after the SHI irradiation. In addition to this, structural characteristics such as unit cell parameters as determined from long-range (Rietveld) refinement are compared to that obtained from short-range (small-box) refinement. Moreover, atomic displacement factor for CdSe also has been determined to study the atomic disorder in the nanocrystal under the influence SHI irradiation. Finally, impact of SHI induced stress generated on the CdSe sample and its influence also has been studied based on the width of the PDF peak.

Modeling swift heavy ion irradiation of substrate-supported two-dimensional material via two-temperature molecular dynamics simulations

This study employs two-temperature molecular dynamics simulations to investigate swift heavy ion irradiation of SiO2 substrate-supported two-dimensional material graphene. Material-dependent electronic and thermal properties are integrated into each region to model the energy transfer between the electronic and atomic subsystems of the studied materials. Simulations of interactions with Xe heavy ions are performed with ion kinetic energies ranging from 0.5 to 25 GeV with electronic stopping powers from ∼2.6 to 17.7 keV/nm. With the studied ion energy range, nanopores with a diameter of up to 5 nm can be formed in graphene due to the thermally driven sputtering effect, while amorphization occurs along the ion track in the SiO2 substrate. The coupling between the substrate and two-dimensional material significantly impacts the structural change due to heat transfer and atomic interactions among different layers of materials. The method applied in this work provides a valuable tool for modeling and understanding the structural modifications induced by ion irradiation in layered structures.

Influence of swift heavy ions irradiation on optical and luminescence properties of Y3Al5O12 single crystals

Optical and luminescence properties of Y3Al5O12 (YAG) single crystals preliminary irradiated by swift heavy ions were studied. Swift heavy Xe ions with fluences ranging from 6·1010 to 2·1012 ions/cm2 were utilized for the irradiation of nominally undoped YAG single crystals. A stable strong induced absorption observed in the 200–600 nm spectral range correlates with the irradiation fluence. It is suggested that several centers are responsible for this induced absorption in YAG single crystals and their possible origin (F-type centers) is proposed and discussed. The swift heavy ions irradiation strongly modifies the luminescence properties of YAG, namely, the excitonic emission at liquid helium temperature is drastically suppressed in heavily irradiated crystals.

Ion Beam-Induced modification in the optical properties of the bilayer of nano-structured amorphous selenium and multi-walled carbon Nanotubes: A study by 70 MeV Ni Ions

In this study, we report improved physical properties of selenium with multi-walled carbon nanotubes (MWCNTs) resulting from a homogeneous mixture of CNT-Se bi-layer thin film by using swift heavy ion irradiation. FESEM micrographs clearly showed the inter-diffusion of Se nanoparticles into MWCNTs following swift heavy ion (SHI) irradiation, EDX validates the elemental composition. The existence of different phonon modes (LO mode and D, G, G' bands) has been found in the Raman spectra of the investigated bi-layer thin films. UV–Visible spectroscopic analysis of pristine CNT-Se thin films show two sharp absorption edges at ∼670 nm and ∼340 nm. After swift heavy ion irradiation, the sharp absorption edge at ∼670 nm exhibits a blue shift, whereas the absorption edge at ∼340 nm exhibits a red shift, confirming the homogeneous mixing of two layers. These remarkable shifts found in the optical properties of CNT-Se bi-layer make the investigated material feasible for many optoelectronic device applications.

Significantly enhanced photo response of hydrazine hydrate reduced graphene oxide films modified with swift heavy ion irradiation of silver (Ag8+) ions

In this paper, a multistep reduction process of graphene oxide (GO) is discussed. It is basically a two-step reduction process. In the first step, the GO sample is reduced by hydrazine hydrate. In the second step, it is further reduced by a swift heavy ion irradiation beam of silver (Ag8+) ions of 100 MeV energies. Ion beam irradiation causes defects in the hydrazine hydrate reduced graphene oxide (rGO) samples. FTIR study confirms the removal of oxygen containing functional groups. The pore volume and pore density of the samples seem to increase with increase in the ion irradiation doses. It is also seen that the electrical conductivity and specific surface area increases with dose of ion irradiation. The prepared samples were tested for photo response measurement and among all the sample, R5 had the highest photo response of 6.25 % at 30 mW/cm2. The photodetection response seems to increase with increase in intensity of light.

The Effect of 147 MeV 84Kr and 24.5 MeV 14N Ions Irradiation on the Optical Absorption, Luminescence, Raman Spectra and Surface of BaFBr Crystals

Today, BaFBr crystals activated by europium ions are used as detectors that store absorbed energy in metastable centers. In these materials, the image created by X-ray irradiation remains stable in the dark for long periods at room temperature. As a result, memory image plates are created, and they are extended to other types of ionizing radiation as well. Despite significant progress towards X-ray storage and readout of information, the mechanisms of these processes have not been fully identified to date, which has hindered the efficiency of this class of phosphors. In this study, using photoluminescence (PL), optical absorption (OA), Raman spectroscopy (RS), and atomic force microscopy (AFM), the luminescence of oxygen vacancy defects to BaFBr crystals irradiated with 147 MeV 84Kr and 24.5 MeV 14N ions at 300 K to fluences (1010–1014) ion/cm2 was investigated. BaFBr crystals were grown by the Shteber method on a special device. Energy-dispersive X-ray spectroscopy (EDX) analysis revealed the presence of Ba, Br, F, and O. The effect of oxygen impurities present in the studied crystals was considered. The analysis of the complex PL band, depending on the fluence and type of ions, showed the formation of three types of oxygen vacancy defects. Macrodefects (tracks) and aggregates significantly influence the luminescence of oxygen vacancy defects. The creation of hillocks and tracks in BaFBr crystals irradiated with 147 MeV 84Kr ions is shown for the first time. Raman spectra analysis confirmed that BaFBr crystals were amorphized by 147 MeV 84Kr ions due to track overlap, in contrast to samples irradiated with 24.5 MeV 14N ions. Raman and absorption spectra demonstrated the formation of hole and electron aggregate centers upon swift heavy ions irradiation.

Modification induced by 120 MeV Ag ion irradiation in ZnS

We report the structural, morphological, and optical properties of ZnS thin films before and after swift heavy ion (SHI) irradiation of 120 MeV Ag ions. These films were deposited by the spin coating method on the glass substrate and irradiated at various ion fluencies from 1 × 1011 to 1 × 1013 ions/cm2. The Grazing Incidence X-ray diffraction (GIXRD), Scanning electron microscopy (SEM), UV–visible transmittance, Photoluminescence (PL), and Raman Spectroscopy were used to characterize these ZnS thin films. The GIXRD patterns show a mixed phase of cubic and hexagonal structure after the ion irradiation. The crystallite sizes of pure and irradiated films are significantly modified. Raman spectroscopy shows a slight increase in the intensity of the 3LO mode of ZnS on irradiation. The SEM image shows nanoflake-like structures in pristine, and the irradiated thin films depict various morphologies (rod, platy, and sphere-like). UV–visible shows a cut-off wavelength at 339 nm and the spectra are blue-shifted with the increase in ion fluence. The Tauc plots reveal the increase in the band gap. The intensity of PL decreases with ion irradiation. Hence the analytical results show that the structural and optical properties of ZnS thin films are altered on swift heavy ion irradiation which may have potential applications in optoelectronic applications.

Change in Superparamagnetic State Induced by Swift Heavy Ion Irradiation in Nano-Maghemite

The effect of swift heavy ion irradiation on sol–gel-prepared maghemite nanoparticles was studied by 57Fe transmission Mössbauer spectroscopy and X-ray diffractometry (XRD). The room temperature Mössbauer spectra of the non-irradiated nano-maghemite showed poorly resolved magnetically split, typical relaxation spectra due to the superparamagnetic state of the nanoparticles. Significant changes in the line shape, indicating changes in the superparamagnetic state, were found in the Mössbauer spectra upon irradiation by 160 MeV and 155 MeV 132Xe26+ ions with fluences of 5 × 1013 ion cm−2 and 1 × 1014 ion cm−2. XRD of the irradiated maghemite nanoparticles showed a significant broadening of the corresponding lines, indicating a decrease in the crystallite size, compared to those of the non-irradiated ones. The results are discussed in terms of the defects induced by irradiation and the corresponding changes related to the change in particle size and consequently in the superparamagnetic state caused by irradiation.

Study of conduction mechanism in swift heavy ion irradiated reduced graphene oxide samples and its applications towards low level detection of SO2 at room temperature

The reduced graphene oxide (rGO) sample is synthesized by the reduction of hydrazine hydrate. The prepared samples further reduced with swift heavy ion irradiation beam of silver (Ag8+) ions of 100 MeV energies. Ion beam irradiation causes defect in the rGO samples which is explained on the basis of Raman study. The removal of oxygen functional groups are explained on the basis of FTIR study. Ion irradiation has increased dc electrical conductivity on reduction. The room temperature dc conductivity of sample S4 is increases from 2.5 × 10−2 to 1.94 S/cm during reduction. The conduction mechanism is accounted by Mott's formulation of 3D variable range hopping model in the temperature range of 77 to 400 K. Along with it, the prepared samples are also tested for gas sensing abilities towards SO2 gas at 5 ppm. The sample exhibits good sensing properties towards analytes at room temperature.

Effect of 710 MeV Bi+51 swift heavy ions irradiation on Se pre-implanted polycrystalline SiC

In this study, the effect of swift heavy ions (SHIs) irradiation in the recrystallization of polycrystalline SiC pre-implanted with selenium (Se) ions and migration of Se was investigated. The main objective of this study is to investigate the role of SHIs with the maximum electronic energy loss greater than 20 keV/nm on structural evolution of initially amorphized pre-implanted SiC and the migration of pre-implanted fission products (FPs). The pristine SiC samples were first implanted with 200 keV Se ions to a fluence of 1 × 1016 cm−2 at room temperature (RT) and at 350 °C. Some of the pre-implanted samples were then irradiated with bismuth (Bi) ions of 710 MeV to a fluence of 1 × 1013 cm−2 at RT. The characterization of both the implanted and implanted then irradiated SiC was conducted using techniques such as transmission electron microscopy (TEM), Raman spectroscopy, scanning electron microscopy (SEM), and Rutherford backscattering spectrometry (RBS). At RT, Se ions implantation caused the amorphization of SiC to a depth of about 187 nm beneath the surface. In contrast, when implanted at 350 °C, the SiC retained its crystalline structure with some defects (i.e., point defects, point defect clusters and some dislocation loops). The SHIs irradiation of the RT implanted SiC resulted in the reduction of the amorphous layer thickness from 187 nm to around 178 nm and led to the formation of nanocrystalline SiC in the amorphous layer. Irradiation of the SiC implanted at 350 °C induced some crystallization of defects. Notably, no evidence of Se ions migration was observed in both the irradiated RT-implanted and the hot-implanted SiC.

Tuning of ion current rectification and ion current saturation of multiple nanochannels in polymeric membrane

The present study gives an insight into ion flow dynamics of aqueous electrolytes via functionalized multiple nanochannels in polyethylene terephthalate (PET) membrane. The selectivity of certain ions (anions/cations) of various electrolyte combinations KCl- KClO4 (S1), KBr-KCl (S2), KBr-KClO4 (S3) over their counter-ions by the nanochannels (generated via swift heavy ion irradiation followed by chemical etching) has been studied. Tuning of the ion transport and ion current rectification has been done using different functionalized nanochannels (with charged carboxyl and protonated amino groups). The impact of ion selectivity of the nanochannels is reflected in the short circuit current and ion current saturation of different systems. The collection of counter ions outside the channels along with the in-built potential due to the flow of ions inside the channels play a crucial role in the ion transport behaviour of the collective system. The cation-selective channels (with charged carboxyl groups) show low rectification ratio compared to the anion-selective channels. The functionalized nanochannels with two -OH polar charge groups (generated through the amino-silane based reagent (3-aminopropyl) trimethoxysilane (APTMS)) exhibit higher current saturation values (S1AP∼31 μA, S2AP∼30 μA and S3AP ∼ 30.5 μA) and higher short circuit current values (S1AP ∼32.3μA, S2AP ∼ 29.6μA and S3AP ∼31.3μA) due to the overlapping of electric double layer (EDL). Systematic study of tuning of ion transport through nanochannels helps to understand the nanofluidic flow and has imminent application in the fabrication of nanoelectronic and bioinspired nanodevices.

Investigations of swift heavy ion induced thermoluminescence effect, trapping parameter analysis, and density functional theory of MgB4O7: Eu phosphor

The present work reports swift heavy ion (SHI) induced thermoluminescence (TL) dosimetric properties and density functional theory (DFT) studies of Eu doped MgB4O7 phosphor. Comparative investigations of structural, and luminescent properties of MgB4O7:Eu phosphor upon irradiation by 100 MeV Ag7+ and Ni7+ ion beams at the varied fluence range from 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2 are presented systematically. Eu doped MgB4O7 phosphor is prepared by facile hydrothermal method. X-ray diffraction pattern of the material reveals its orthorhombic structure with crystallite size of ∼30 nm. Fourier transform infrared spectroscopy (FTIR) studies demonstrate loss of crystallinity of material after the SHI irradiations. Correlation of stopping powers and projectile range calculations is performed using SRIM software. The investigated photoluminescence properties show emission bands located in the orange-red region with prominent peaks centered at ∼593 nm and ∼625 nm corresponding to 5D0→7F1 and 5D0→7F2 transitions of Eu3+ion. The influence of ion beam fluence on the photoluminescence properties has been explored. Variation in the intensity of the PL peaks without any shift in the peak positions is observed at different ion fluence. The TL glow curve of phosphor exhibits two major dosimetric peaks (a) at 185 °C and 275 °C and (b) at 172 °C and 273 °C upon Ag7+ and Ni7+ ion beam irradiation respectively. The phosphor shows fairly good linear dose response in the range of 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2. Fading measurements reveal 10% and 12% fading for the irradiation of Ag7+ and Ni7+ ions respectively in two months. Trapping parameter calculations of SHI irradiated phosphors are carried out via various TL glow curve analysis methods such as, peak shape method, whole glow peak method, and glow curve deconvolution method. Efficient thermoluminescence properties of MgB4O7:Eu make it a potential phosphor material and promise to provide avenue into swift heavy ion dosimetry applications. DFT computational studies performed to obtain the electronic structure of Eu doped MgB4O7 phosphor support the experimental results of crystal structure, symmetry and electronic structure studies.