Papers by Keyword: Ion Beam

Abstract: This study investigates an enhancement of carbon-based materials, including multi-walled carbon nanotubes (MWCNTs) and graphite, through Ion Assisted Reaction (IAR) and metal nanoparticle deposition using Physical Vapor Deposition. The IAR process employed Ar⁺ ion beams in reactive gas environments, effectively introducing hydrophilic functional groups such as hydroxyl (-OH) and carboxyl (-COOH) on the MWCNT surfaces. This modification significantly improved dispersion behavior of the treated MWCNTs, particularly in non-polar solvents like N-Methyl-2-pyrrolidone (NMP). Results indicated that the treated MWCNTs demonstrated a slower sedimentation rate compared to untreated samples, with enhanced stability over 120 minutes in NMP. Graphite was modified with copper nanoparticles on its surface using magnetron sputtering in PVD system, leading to a uniform distribution of the modified graphite in matrix. SEM analysis revealed that this modification enhanced the surface roughness of the graphite, facilitating stronger interfacial adhesion with polymer epoxy resin. Composites incorporating these nanoparticle-coated graphite fillers (NPP graphite) exhibited superior thermal and mechanical properties. For instance, a 15% increment in thermal conductivity was observed in epoxy resin composites containing NPP graphite compared to those with untreated graphite. This improvement was attributed to the metallic Cu nanoparticles acting as thermal bridges, effectively transferring heat within the composite matrix. Mechanical properties were evaluated by blending modified fillers into polymer matrices, including polyvinyl chloride (PVC) and polyethylene (PE), with filler concentrations varying from 5 vol% to 15 vol%. Tensile testing and SEM analysis of the fractured surfaces indicated that NPP graphite composites achieved uniform dispersion, reduced agglomeration, and improved interfacial bonding. This study demonstrates that physical surface modification techniques such as IAR and PVD effectively overcome limitations associated with conventional chemical methods. This approach not only improves the dispersion and interfacial adhesion of carbon-based fillers but also enhances their thermal and mechanical performance.

Abstract: In recent studies, multifunctional oxide thin films have been given attention because of their special properties, such as ferroelectricity, gas sensitivity, and magnetism. Ion beam irradiation arose as a well-developed technique for tuning such properties. This study investigates the ion beam irradiation effects of He, Ni, and Kr ions on BiFeO₃, SnO₂, and ZnO thin films, respectively. The study utilized the 2013 version of Stopping and Range of Ions in Matter (SRIM) software to identify ion trajectory distribution and oxygen target vacancy differences on the Transport of Ions in Matter (TRIM) calculation types at various ion energies. A greater distribution of ion trajectories and higher peaks of oxygen target vacancies in oxide thin films were generated from monolayer TRIM than full cascade TRIM for all ion–thin-film pairs. The monolayer TRIM is preferable for ion beam irradiation of oxide thin films with its greater oxygen target vacancies and ion trajectory distribution for better analysis of ferroelectric coercive fields, adsorbed oxygen ions interaction with gas molecules, and the emergence of green emission for photoluminescence. The use of SRIM allows an alternative yet more flexible way of analyzing beam irradiation effects on oxide films considered in this work without resorting to costly or sophisticated experimental setups, which are a usual approach considered in most of the work under this topic. As such, the results presented here provide an initial or complementary basis should irradiation effect experiments require analysis of ion trajectories and oxygen vacancies.

Abstract: This paper reports optical propertites of negatively charged N_CV_Si^- centers in silicon carbide (a nitrogen substituting for a carbon atom adjacent to a silicon vacancy) whose emission wavlength is 1100-1500 nm at room temperature. High-purity semi-insulating (HPSI) 4H-SiCs are implanted with high energy N ion beams and subsequently thermally annealed to form N_CV_Si centers. We investigated a wide range of N ion implantation dose using a micro ion beam implantation technique and observed the photoluminescence intensity from the SiC-NV centers. We show that under conditions of heavy implantation, the excitation laser power excites residual defects and their fluorescences intereferes with the emission from the N_CV_Si^- centers. These results allow us to clarify the requirements to optically detect isolated single N_CV_Si^- centers at lightly implanted conditions.

Abstract: In constructing the low energy accelerator for plant modification the most important part is the ion source. In the conventional cold cathodes and hot filament ion source methods the filament continuously burns out over time, has a shorter lifespan and requires venting of the ion source to atmosphere. Henceforth the Radio frequency (RF) antenna ion source or “non-thermionic ion source” with 13.6 MHz was used in the accelerator as well as it being easy to generate varie the plasma souce and stability. This ion source can produce a particle beam of about ~30 to 40 mA current. The ion particle was extracted by the first zero voltage extraction rod electrode method focusing the ion beam of 0-30 kV with the second rod electrode after which the third rod electrode has zero voltage. In calculating and designing this system via the Simion8.0 Program, the result showed that the Ar⁺ ion beam with 30 keV can be focused with 1 cm diameter beam at the distance of 10 cm of the drift space.

Abstract: Radiation effects of ion beams in perovskite oxide memristors are analyzedand linked to absorbed dose values, calculated from simulations of ion transport. Several ion species were used in simulations, chosen to represent certain commonly encountered radiation environments. Results indicate that considerable formation of oxygen ion - oxygen vacancy pairs, as well as advent of displaced rare earth and alkaline atoms, is to be expected. Oxygen vacancies can lead to a decrease or increase of active layer resistance, depending on applied voltage polarity. The loss of vacancies from the device is bound to impair the performance of the memristor. Calculated absorbed dose values in the memristor for various incident ion beams are typically on the order of several kGy.

Abstract: The effect of ion beam bombardment on the optical and mechanical properties of ultra-high molecular weight polyethylene (UHMWPE) was investigated. UHMWPE polymer samples were bombarded with 150 keV N₂ ions under vacuum at room temperature to high fluences ranging from 1x10¹⁶ to 2x10¹⁷ ions cm^-2. The untreated as well as treated samples were investigated by ultraviolet-visible (UV-Vis) spectrophotometer and Vickers micro-hardness techniques. The direct and indirect optical band gap decreased from 2.9 and 1.65 eV for pristine sample to 1.7 and 1 eV for those bombarded with N₂ ion beam at the highest fluence, respectively. With increasing ion fluence, an increase in the number of carbon atoms per conjugation length, N and number of carbon atoms per cluster, M in a formed cluster were observed. A significant improvement in surface hardness was obtained by increasing the ion fluence.

Abstract: Abstract. HIPIB irradiation of magnesium alloy is carried out at a specific ion current density of 100 A/cm2 with shot number from one to ten in order to explore the effect of shot number on crater formation of magnesium alloy. Surface morphologies, surface roughness and mean spacing of surface profile irregularities of the irradiated samples are examined by scanning electron microscopy (SEM) and profilometer technique, respectively. It is found that the surface roughness, the mean spacing of surface profile irregularities, and the maximum crater diameter on the irradiated surface increase with increasing shot number, whereas the crater density decreases as the shot number increases.

Abstract: The current knowledge of the transcriptome is limited to understand the exact molecular mechanism of the ion-implantation biological effects on cereals. In order to investigating the overall characteristics of the transcript profiles associated with these puzzling biological effects. We used the Agilent Rice Oligo Microarray （4×44K）Genome Array to learn the molecular mechanism in rice responding to ion-implantation. Rice seeds were implanted by the Nitrogen ion beam and their vigor index was investigated at ten days after germination. Total RNAs was extracted from the rice seedlings at 96 hour after germination and hybridized by the genome genechip. The results of measuring of the vigor index showed that lower-dose implantation of the nitrogen ion beam (6×1017 N+/cm2) promoted the vigor index of the rice seedlings and the higher-dose implantation (9×1017 N+/cm2) damaged the rice seedlings because of the smaller vigor index than the control. The analysis of the genechip array showed that there were 982 transcripts expressed differentially (fold change＞2 and P value＜0.05) including 429 up-regulated transcripts and 553 down-regulated transcripts under the dose3 6×1017 N+/cm2. 30 out of the 553 down-regulated transcripts were involved in 48 pathways. 14 out of these 30 transcripts were associated with more than two interrelated pathways. Os04g0518400 (Phenylalanine ammonia-lyase 2 (PAL; EC 4.3.1.5; down-regulated 3.3 folds; p value=0.005) were involved in 7 pathways, Os07g0446800 (Hexokinase; dwon-regulated 2.8 folds; p value =0.006) were involved in 12 pathways, and Os02g0730000 (Mitochondrial aldehyde dehydrogenase ALDH2a; down-regulated 2.2 folds; p value=0.019) were involved in 13 pathways. These results revealed that down-regulated genes involving important pathways were compatible with the distinct cellular events in response to implantation of low-energy ion beam and supplied the first comprehensive and comparative molecular information for further understanding the mechanism underlying implantation of the low-energy nitrogen ion beam.

Abstract: In this work the capability of the proton induced X-ray emission (PIXE) technique to monitor a rapid, non-destructive and accurate quantification of Al on or inside SiC is discussed. Optimization of PIXE acquisition parameters was performed using as reference, a thin Al film (2.5 nm) thermally evaporated onto silicon carbide substrate. In order to improve the sensitivity for Al detection and quantitative determination, a systematic study was undertaken using proton ion beam at different energies (from 0.2 to 3 MeV) with a different tilting angle (0°, 60°, and 80°). The limit of detection (LOD) was found to be lower than 0.02 nm. The optimum PIXE conditions (energy, angle) were applied for determining the Al doping concentration in thin (1 µm) 4H-SiC homoepitaxial layer. The Al concentration as determined by PIXE was found to be 3.9x1020 at/cm3 in good agreement with SIMS measurements, and the LOD was estimated to be 6x1018 at/cm3.

Abstract: The radiation technology has been applied extensively in the field of biological engineering, tissue engineering, medical practices and so on. It also plays an important role in the sterilization and modification of biomaterials. This work reviews recent development of several types of radiation technology which have been applied in the field of medical biomaterials.