Nickel Ion Irradiation Research Articles

The effect of nickel additive and ion irradiation on the structural and optical properties of lithium borate glasses

The study investigates the impact of nickel oxide (NiO) doping (0%, 0.1%, 0.2%, and 0.3% wt%) on the glass composition 85B2O3-15Li2O using the melt quenching technique. Both X-ray diffraction (XRD) and FTIR confirm the amorphous nature and functional groups. Density, molar volume, average boron separation, ion concentration, interionic distance, polaron radius,. UV-visible absorption (200–1100 nm) was also recorded before and after nitrogen ion beam irradiation (fluence: 8x1017 and 16x1017 ion/cm2). Results indicate a decrease in the optical energy gap (Eoptical gap) and an increase in Urbach’s energy (EU) with higher NiO content, especially post-irradiation. Nitrogen ion irradiation at higher doses (16x1017 ion/cm2) induces more significant effects, attributed to increased non-bridging oxygen species (NBOs) formation and finally dielectric parameters were measured from 100 Hz to 100 kHz. Overall, the ability to tailor borate glass properties via nitrogen ion irradiation holds promise for diverse technological applications in optoelectronics, photonics, sensors, and radiationdetection

Structural and optical properties of lithium borate glasses under extreme conditions of ion irradiation

Lithium borate (LBO) glasses of the composition 10LiO2.90B2O3 were prepared by melt quenching technique and characterized for morphological, structural, and optical properties before and after the exposure to the extreme conditions of 100 MeV Ni ion irradiation. Both the morphological images and structural properties confirm the transformation of LBO glasses from amorphous to polycrystalline nature. This Ni irradiation provides thermal energy that causes the ceramization of glass. The beam interacts with the material where the top layer of the glass remelts, and ultrafast re-solidification occurs after the termination of the ion beams. The Rietveld refinement using the x-ray diffraction data shows that the irradiated LBO possesses a monoclinic crystal structure of lithium pentaborate pentahydrate (B5H10LiO13). The FTIR spectra of Ni ion irradiated glasses show the creation of non-bridging oxygens (NBO) by the formation of BO4 units at the expense of BO3 units. The direct band gap and the Urbach energy of the glasses are affected by the nickel ion irradiation and are in the range 2.73 to 2.55 eV and 0.59 to 0.42 eV. The refractive index also reveals a minor change (1.66 to 1.63). The molar electronic polarizability, metallization criteria, and transmission coefficient were estimated. The coexistence of crystalline and amorphous phases leads to a multiscale phase structure that has multilevel relaxation processes. This is a suitable condition for the improvement of the rheological properties of glass and glass ceramics. Future work involves optimization of the coexistence of these two phases during irradiation.

Modification of the electronic structure and the electrical properties of ZnO thin films by nickel-ion irradiation at room temperature

Radio-frequency (RF) sputtered ZnO films were investigated as a function of the Ni-ion irradiation dose at room temperature. The prepared ZnO films were irradiated with Ni-ions at an acceleration energy of 130 MeV in the dose range from 5 × 1011 ions/cm2 to 1 × 1013 ions/cm2. The electrical properties of the irradiated ZnO films changed with changing Ni-ion irradiation dose. In order to explain the change in the electrical properties of ZnO films, we investigated the physical properties and the electronic structure, such as the physical structure, the molecular orbital in the conduction band, and the band edge state below the conduction band. The physical structure and the physical composition showed no changes, regardless of the Ni-ion irradiation dose. On the other hand, the electronic structure showed a drastic modification of the hybridized molecular orbital ordering of the Zn 4sp and the O 2p in the conduction band. In addition, two distinct band edge states below the conduction band were observed with increasing Ni-ion irradiation dose. These remarkable changes in the electronic structure could be correlated to changes in the electrical properties.

Modulation of gene expression in endothelial cells in response to high LET nickel ion irradiation.

Ionizing radiation can elicit harmful effects on the cardiovascular system at high doses. Endothelial cells are critical targets in radiation-induced cardiovascular damage. Astronauts performing a long-term deep space mission are exposed to consistently higher fluences of ionizing radiation that may accumulate to reach high effective doses. In addition, cosmic radiation contains high linear energy transfer (LET) radiation that is known to produce high values of relative biological effectiveness (RBE). The aim of this study was to broaden the understanding of the molecular response to high LET radiation by investigating the changes in gene expression in endothelial cells. For this purpose, a human endothelial cell line (EA.hy926) was irradiated with accelerated nickel ions (Ni) (LET, 183 keV/µm) at doses of 0.5, 2 and 5 Gy. DNA damage was measured 2 and 24 h following irradiation by γ-H2AX foci detection by fluorescence microscopy and gene expression changes were measured by microarrays at 8 and 24 h following irradiation. We found that exposure to accelerated nickel particles induced a persistent DNA damage response up to 24 h after treatment. This was accompanied by a downregulation in the expression of a multitude of genes involved in the regulation of the cell cycle and an upregulation in the expression of genes involved in cell cycle checkpoints. In addition, genes involved in DNA damage response, oxidative stress, apoptosis and cell-cell signaling (cytokines) were found to be upregulated. An in silico analysis of the involved genes suggested that the transcription factors, E2F and nuclear factor (NF)-κB, may be involved in these cellular responses.

Single-mode waveguides generated in Nd3+-doped silicate glass by nickel ion irradiation

Single mode waveguide in Nd3+-doped silicate glass substrate was fabricated by ion implantation technique. Nd3+-doped silicate glass is irradiated with 3MeV Ni ions at a fluence of 5×1014ions/cm2. The prism-coupling method is used to measure the effective refractive indices of the waveguide dark modes. Only one mode is found, in which its effective index (neff=1.5207) is higher than the substrate index (nsub=1.5202). The refractive index distribution of the waveguide was reconstructed; and the near-field intensity distribution is in a good agreement with simulated modal profiles. Propagation losses of the light in the waveguides were measured by the back-reflection method. It is found that after annealing the propagation loss of waveguide is effectively reduced.

A study of the effect of titanium on the void swelling behavior of D9 steels by ion beam simulation

The void swelling behavior of D9 with 0.25Ti and D9 with 0.15Ti modified steels was studied using heavy ion irradiation. The cold worked samples were pre-implanted with a uniform helium concentration of 30 appm spanning a width of about 640 nm. This was followed by a 5 MeV nickel ion irradiation to create a peak damage of 100 dpa at a damage rate of 7 × 10 −3 dpa s −1 at various temperatures between 700 and 970 K. The gross swelling up to the implanted range was measured by step height measurements. It is found that the peak swelling temperatures and the magnitude of swelling are different for the alloys studied. Positron lifetime measurements of the unirradiated alloys annealed at various temperatures show differences in the formation of TiC precipitates. The difference in void swelling behavior in these two alloys with titanium variation is discussed on the basis of the role of titanium on the vacancy migration and TiC precipitate formation.

Effect of titanium on the void swelling behavior in (15Ni–14Cr)–Ti modified austenitic steels studied by ion beam simulation

The void swelling behavior of (15Ni–14Cr)–0.25Ti and (15Ni–14Cr)–0.15Ti modified steels are studied using heavy ions from an accelerator. The cold worked samples have been pre-implanted with a uniform helium concentration of 30 ppm spanning a width of about 640 nm. This was followed by a 5 MeV nickel ion irradiation to create a peak damage of ∼100 dpa at damage rate of 7 × 10 −3 dpa/s at various irradiation temperatures between 700 and 970 K. The gross swelling in the implanted range is measured by step height measurements. It is found that the peak swelling temperatures and the magnitude of swelling for the alloys are different. Positron lifetime measurements of the un-irradiated alloys which are annealed at various temperatures show different TiC precipitates formation behavior. The difference in void swelling behavior in these two alloys with titanium variation is discussed on the basis of the role of titanium on the vacancy migration and TiC precipitate formation.

Application of positron beam Doppler broadening technique to ion beam irradiation in nickel

The formation processes of vacancy-type defects induced by ion irradiation in nickel were investigated with a variable-energy positron beam Doppler broadening technique in order to find the appropriate experimental condition for in situ positron beam experiments. Nickel ion irradiation at 300–343 K induces an S parameter increase, but the dependence of the S parameter on positron energy is very similar to that of cold-rolled nickel, which suggests positron trapping by small vacancy-type defects such as SFTs. The best experimental condition for investigation of cavity nucleation process by in situ positron beam Doppler experiments is suggested to be around 0.1–0.4 dpa at 773 K.

Effects of irradiation on the microstructure and mechanical properties of nanostructured materials

Nanostructured materials should present a good resistance to irradiation because the large volume fraction of grain boundaries can be an important sink for radiation-induced defects. The objective of the present study is to experimentally investigate the irradiation impact on the microstructure and mechanical properties in nanostructured materials. Nickel and Cu-0.5Al2O3 specimens were synthesized by electro deposition (ED) and severe plastic deformation (SPD). Mean grain size of the unirradiated specimen is about 30 nm for the ED Ni and about 115 nm for the SPD Ni. 590 MeV proton irradiation and 840 keV nickel ion irradiation were conducted at room temperature. Vickers hardness measurements and transmission electron microscope observation were performed to examine the impact of irradiation on nanocrystalline materials. It appears that the irradiation induced microstructure in Ni and in Cu-0.5Al2O3, which leads to hardening, consists exclusively of stacking fault tetrahedra. Their density appears much lower than in the case of coarser grained material. These results, experimentally showing the resistance of nanostructured material to radiation damage, are presented here.

Nickel ion irradiation of plasitically deformed martensitic titanium nickel thin films

At present, little is known about the response of the martensitic phase in TiNi alloys to heavy ion irradiation. However, previous studies [2,3] of ion and electron irradiation show that these alloys are highly susceptible to disorder and amorphization at damage levels below 1 dpa. This substantially affects their transformation characteristics and their shape memory effect. The present study focuses on the effect of 5 MeV Ni ion irradiation of plastically strained (epsilon-4%) martensitic TiNi thin films, which is used as a processing technique for a novel out of plane bending actuator. Conceptually, the frustration of the martensitic transformation due to ion beam damage in a 2mum surface layer of a 6mum thick film will create a sharp differential latent strain on reverse transformation. This latent strain causes a two-way bending motion during cycling heating and cooling. This processing technique can be used to do useful mechanical work on both beating and cooling. To better understand the behavior of these ion irradiated thin films, TEM observations and motion experiments were conducted. Results are presented and discussed as they relate to the ion induced microstructure and its influence on the martensitic transformation.

Pinning property of Bi-2212 single crystals with columnar defects

The critical current density and the irreversibility field were measured before and after nickel ion irradiation for Bi-2212 single crystals in an optimally doped or an overdoped state in a magnetic field parallel to the direction of irradiation. The critical current density was theoretically calculated by using the summation theory and the flux creep-flow model. From the comparison with experimental results the condensation energy density was estimated for each specimen. These results are compared with a similar analysis on three-dimensional Y-123.

Chromium and nickel ion irradiation effects on the low- and high-temperature metal-semiconductor transitions in (V1−xCrx)2O3 ceramics

Chromium doped vanadium sesquioxide [(V1−xCrx)2O3] ceramic samples have been irradiated using medium energy chromium and nickel ions (52Cr:572 MeV, 64Ni:640 MeV) at various fluences (4×1011–1.1×1014 ions/cm2) and doping rates (x=0.3, 0.6, and 0.7). Irradiation has been carried out under vacuum and at room temperature. Irradiated samples have been characterized by electrical resistivity measurements as a function of temperature for the low- and the high-temperature transitions in the (V1−xCrx)2O3 system. Irradiation by chromium and nickel ions creates bilayered samples as the ions mean projected range were smaller than the sample thickness. The bilayer structure is characterized by two transitions at low temperature. Dealing with the high temperature positive temperature coefficient transition, the negative temperature coefficient behavior above this transition has been considerably attenuated due to the bilayered structure. In situ measurements on an irradiated sample have shown that after annealing the electrical characteristics for the low- and the high-temperature transitions tend to be close to those of an unirradiated sample. However, even an annealing at 380 °C does not eliminate all the irradiation effects.

The effect of oxygen on void stability in ion-irradiated steel

The effect of oxygen on void stability in an Fe-17Ni-13Cr austenitic ternary alloy has been investigated using 15 MeV nickel-ion irradiation at elevated temperatures and preimplantation of 6 MeV oxygen at room temperature. The nickel irradiation was performed over a temperature range of 550 °C to 650 °C. Utilizing transverse specimen preparation techniques, the irradiated steel was examined by transmission electron microscopy (TEM). As little as 10 appm preimplanted oxygen caused a significant increase in the void number density when the steel was irradiated at 550 °C. A near-surface void-denuded zone occurs in the irradiated steel, while a region depleted of visible voids also occurs in the steel injected with 300 appm oxygen or greater and irradiated at 550 °C.

Observations of void swelling of Nimonic PE16 alloy under temperature-cycling during nickel-ion irradiation

Studies have been made of Nimonic PE16 alloy to determine the void swelling under selected temperature-cycle conditions during 46 MeV Ni6+ irradiation to 60 dpa. Six different starting conditions were investigated: 1090° C and 1035° C solution-treated (ST); ST plus 710° C and 750° C aged (STA) and ST + 16% cold-work plus aged (STCWA). All samples were pre-injected with 20 appm He at 525° C and subsequently irradiated in 5 dpa increments after selected temperature changes of ± 25 ° C from a base temperature of 525° C. Two cyclic patterns were explored but in both cases the total void swelling was < 0.25% for all material conditions except 1035° C ST where swelling of 0.4% was observed. The differences in swelling conditions were small and no adverse swelling response was apparent under the cyclic conditions employed. For temperature reductions of 50° C from 550° C and increases of 50° C from 500° C the swelling was reduced with respect to 525°C isothermal values. This was attributed to a large reduction in void concentration, possibly arising from cavity shrinkage by interstitial absorption.

The influence of silicon and helium on the microstructural stability of ion-irradiated incoloy DS alloys

In order to test their void swelling behaviour under irradiation, several alloys based on the solid-solution nickel alloy Incoloy DS (18Cr-38Ni-Fe) with additions of 0.05, 0.43, 0.92 and 2.24 wt% Si have been studied using 4 MeV helium and 46 MeV nickel ion irradiation in the Harwell VEC. For irradiations of 60 dpa with 10 appm He the void swelling decreased from ~ 0.9% to negligible levels with increasing silicon content. After irradiation to 90 dpa following injection with 10 appm He the 2.24% Si alloy showed <1.0% swelling at an apparent peak swelling temperature of 625° C. This alloy was subsequently irradiated to check the swelling response with concentrations of helium and hydrogen appropriate to fusion-reactor conditions. Following irradiation to 60 dpa after 1000 appm He injection the swelling peak was shifted to 575° C where a swelling maximum of 4% was observed. At 625° C with 1000 appm He alone, swelling was 2.0% compared with 1.2% in samples injected with 1000 appm He +1000 appm H. This small reduction in swelling was associated with a higher cavity (bubble) concentration in the hydrogen implanted sample. Fine-scale precipitation of Ni 3Si(γ'), η-carbide and G-phase was observed after irradiation together with helium bubbles attached to the η- and G-phase precipitates. The precipitation and void swelling was significantly greater in irradiated samples containing 1000 appm He than in those with 10 appm and irradiated to 90 dpa. It is concluded that although the Incoloy DS alloy possibly has a potential for fission-reactor core applications it has little to commend it for fusion-reactor use where the high swelling response, microstructural instability and likely long-term induced activation arising from the higher nickel content are clearly undesirable factors.

Nucleation and amorphization of radiation-produced phases in a modified austenitic stainless steel during Ni-ion irradiation

The nucleation and amorphization of radiation-induced (G) and radiation-enhanced (η) phases in a silicon- and titanium-modified austenitic stainless steel have been studied under nickel-ion irradiation. These silicon- and nickel-enriched phases form under high-temperature (950 K) irradiation as the result of radiation-induced segregation to radiation-produced interstitial dislocation loops. Availability of carbon promotes the formation of η phase relative to G phase. Under lower temperature (450 K) irradiation, G and η phases are amorphized without significant change in composition of metallic elements. Two carbide phases (MC, M23C6) remain crystalline for the same irradiation conditions. The amorphization of the silicides may result from (1) radiation damage increasing their free energy above that of the amorphous state or (2) direct formation of the amorphous phase in the damage cascade.

Effects of 14 MeV nickel ion irradiation on nickel-copper alloys observed in cross-section

Abstract Two Ni-Cu alloys, Ni-10 at% Cu and Ni-50 at% Cu, as well as pure Ni were irradiated with 14 MeV Ni ions at a homologous temperature of T / T m = 0.45 up to 100 dpa at the peak damage depth. Most of the samples were pre-injected with 5 MeV oxygen ions at room temperature before Ni ion irradiation. The depth dependence of the ion damage structure was studied by TEM with the samples prepared in cross-section. The results obtained from the Ni-Cu alloys and pure Ni are compared. While voids formed readily in the oxygen implanted Ni after Ni ion irradiation, most defect clusters in the irradiated Ni-Cu alloys were dislocation loops. Voids observed in Ni-10Cu alloy were mostly located in the oxygen implanted region, with only a few located at the peak damage depth. No voids were found in the Ni-50Cu alloy. The dislocation loop density in the Ni-50Cu samples was 5–7 times higher than that in the Ni-10Cu samples, however, the loop size was much larger in the latter. The mechanism of void suppression in Ni-Cu alloys is discussed in terms of the trapping of vacancies and gas atoms.

Observations of void swelling in selected austenitic alloys during ion irradiation under a rising temperature ramp

Results are given of a TEM study of the void swelling behaviour of CW AISI 321 (En58B), CW FV548 stainless steel and STA Nimonic PE16 alloy during 46 MeV nickel ion irradiation under a near-linear rising temperature ramp. The dose range for the ramp was 0–75 dpa and four temperature ranges were investigated using 50 ° C intervals from 500–550 ° C, 525–575 ° C, 575–625 ° C and 625–675 ° C. Swelling in CW 321 was found to be no greater than that observed after isothermal irradiation to 75 dpa at temperatures corresponding to the end-of-ramp temperatures. This was not the case for CW FV548 where the swelling for the temperature ranges of 525–575 ° C and 575–625 ° C was slightly greater than that observed under isothermal irradiation to 75 dpa. Swelling in STA PE16 in the lower temperature ranges of 500–550 ° C and 525–575°C was much higher than corresponding isothermal values but in the 600–700 ° C temperature range the swelling was close to isothermal values. The results on PE16 indicate that a steady increase in irradiation temperature from just below or just above the low temperature cut-off into the void swelling region produces a significant increase in swelling with respect to that expected under isothermal conditions. Possible interpretations of the observed swelling behaviour in these alloys are discussed.

Void swelling in 12R72HV austenitic steel after 46 MeV Ni6+ irradiation to 120 dpa in the Harwell VEC

A simulation of neutron-induced void swelling in the Sandvik 12R72HV alloy has been carried out using 46 MeV nickel-ion irradiation in the Harwell Variable-Energy Cyclotron to doses of 50, 70 and 120 dpa at temperatures of 525, 575, 625 and 675°C. The alloy was irradiated primarily in two starting conditions: ST and STCWA, although some irradiations to 50 dpa only were made on STA material. Examinations using TEM showed that voids were formed over the whole temperature range with maximum swelling occurring in the range 575–625°C. For a dose of 120 dpa at 575°C swelling of ~14% in STCWA and ~9.5% in ST alloy was observed. Radiation-induced recrystallisation was observed at 625 and 675°C but not at the lower temperatures. Irradiation-induced precipitates were observed at all temperatures and comprised of fine-scale distributions at the lower temperatures with coarser precipitates occurring at 625 and 675°C. The phases observed comprised of M23C6; M6C and Si-rich G-phase which was attached to voids. The observations suggest that the 12R72HV alloy will exhibit a medium-to-high swelling response during in-reactor irradiation to 120 dpa.

Microstructural evolution in helium doped HT-9 ferritic steel following 14 MeV nickel ion irradiation

A set of HT-9 specimens uniformly pre-implanted with 100 appm of helium up to a depth of 1.3 μm were irradiated with 14 MeV nickel ions up to 60 dpa at temperatures of 400, 500 and 600 °C. Cavities were observed in the He-doped specimens irradiated at 500 and 600 °C. The maximum local swelling was found to be 0.1% in the specimen irradiated at 500 °C to 60 dpa. There was no measurable difference in precipitate evolution and dislocation loop structure between samples irradiated with and without pre-implanted helium. It is concluded that free gas atoms are essential to the formation of cavities in heavy ion irradiated HT-9. The overall low swelling characteristics of this alloy show that HT-9 is a highly swelling resistant material even in the presence of considerable amounts of helium.