Effects of 3.5 MeV proton irradiation on pure zirconium

The effects of high energy proton irradiation on pure zirconium were investigated in this study. The annealed Zr specimens (50 mm × 3 mm × 0.8 mm) were irradiated by 3.5 MeV hydrogen ions with dose ranges from 1×10¹³ to 1 × 10¹⁵ ions/cm² at 335 K. The range of the proton beam penetration was measured to be 68-70 μm, depending on the surface, which is in good agreement with the SRIM simulation results. X-ray diffractometer analysis revealed that the peak intensity of the basal plane increased and the position of the peak shifted due to the proton irradiation. Field emission scanning electron microscopy results showed that with increasing irradiation dose hydrogen micro-bubbles formed, concentrated, interconnected, and eventually burst due to the excessive hydrogen pressure inside, causing surface-crack development. Measured yield and ultimate tensile strength seemed to be insignificantly affected by the proton irradiation.     

Characterization and performance of fuel cells using BaCe0.9Y0.1O3?δ electrolyte modified by an ion beam

To investigate the effects of ion irradiation for improving the performance of a fuel cell, specimens were irradiated with Ar⁺ ion beams at total fluences of 0, 1×10¹⁷ and 5×10¹⁷ ions/cm². After the ion-beam processing, measurements of the hydrogen concentration at the near-surface and of the electrical conductivity of the specimens, along with scanning electron microscopy observations, showed that the increase in oxygen vacancies formed due to irradiation contributed not only to an increase in hydrogen concentration on the surface but to an improvement in proton conductivity. These results suggest that this method is effective for improving the proton conductivity in proton-conducting Y-doped BaCeO_3???. Additionally, unit fuel cells were fabricated using the Y-doped BaCeO_3???s irradiated by the ion beam with different fluences. It was observed from their I-V and I-P curves, that with the increase in Ar⁺ fluence, both the current density and power density were improved.     

XRD and SEM Investigation of Swift Heavy Ion-Irradiated Polyvinylidene Fluoride Thin Films

Polyvinylidene fluoride (PVDF) films of different thicknesses are irradiated with 100 meV Ag-ion and 75 meV Oxygen-ion beams at different fluences to study the effects of swift heavy ion (SHI) irradiation in PVDF. The change in physical, chemical, and surface morphological properties of irradiated films are investigated using x-ray diffraction, Field emission scanning electron microscopy (FESEM), and energy dispersive analysis by x-ray (EDAX) techniques by taking unirradiated (pristine) films as reference. The diffraction pattern shows that PVDF polymer is in semi-crystalline form and possesses crystalline α-, β-, and γ-phases. A decrease in the crystallinity and crystallite size has been observed when PVDF is irradiated with 100 meV Ag-, and also Oxygen ions at a higher fluence of 5.675 × 10¹² ions/cm². However, an increase in crystallinity and decrease in crystallite size are observed when PVDF is irradiated with oxygen-ion beam at lower fluence 5.625 × 10¹¹ ions/cm². The structural parameters such as degree of crystallinity, crystallite size, microstrain, and dislocation density have also been estimated. EDAX result shows that the chemical composition of PVDF is invariant under SHI irradiation, which is in agreement with our earlier results of FTIR. FESEM analysis shows granular microstructure with small porosity on SHI irradiation.     

Mitigation of Stress Corrosion Cracking Susceptibility of Machined 304L Stainless Steel Through Laser Peening

The paper describes an experimental study aimed at suppressing stress corrosion cracking susceptibility of machined 304L stainless steel specimens through laser shock peening. The study also evaluates a new approach of oblique laser shock peening to suppress stress corrosion cracking susceptibility of internal surface of type 304L stainless steel tube. The results of the study, performed with an indigenously developed 2.5 J/7 ns Nd:YAG laser, demonstrated that laser shock peening effectively suppresses chloride stress corrosion cracking susceptibility of machined surface of type 304L stainless steel. In the investigated range of incident laser power density (3.2-6.4 GW/cm²), machined specimens peened with power density of 4.5 and 6.4 GW/cm² displayed lower stress corrosion cracking susceptibility considerably than those treated with 3.2 and 3.6 GW/cm² in boiling magnesium chloride test. Oblique laser shock peening, performed on machined internal surface of a type 304L stainless steel tube (OD = 111 mm; ID = 101 mm), was successful in introducing residual compressive surface stresses which brought about significant suppression of its stress corrosion cracking susceptibility. The technique of oblique laser shock peening, in spite of its inherent limitations on the length of peened region being limited by tube internal diameter and the need for access from both the sides, presents a simplified approach for peening internal surface of small tubular components.     

Temperature-Dependent Properties of Spray-Deposited ITO Thin Films

Sprayed indium tin oxide (ITO) thin films are synthesized by mixing adequate quantities of ethanolic solutions of indium trichloride and stannic chloride at different substrate temperatures. The pyrolytic decomposition temperature affects the properties and morphology of ITO samples. X-ray diffraction results showed that the films are polycrystalline with cubic structure and exhibit preferential orientation along (222) plane. The SEM and AFM studies indicated that the surface morphology of the samples increases with substrate temperature. The typical I₅₀₀ sample is composed of cubic grains and has carrier concentration of 3.26 × 10²⁰ cm^?3 and mobility of 9.77 cm²/V s. The electrical resistivity of ITO films decreased with increasing deposition temperature. The highest figure of merit of film is 4.4 × 10^?3 Ω^?1. Optical absorption studies reveal that films are highly transparent in the visible region and band gap increases with substrate temperature owing to Moss-Burstein effect.     

Electrically Insulative Performances of Ceramic and Clay Films Deposited via Supersonic Spraying

Supersonic spray coating techniques were applied to deposit ceramic and clay particles as films for use in electrical insulation. TiO₂ and Al₂O₃ ceramics were aerosol-deposited under vacuum while kaolinite, montmorillonite, and bentonite clays were deposited by cold spraying in open air. The electrical resistivity of Al₂O₃ and TiO₂ were ~10⁹ and ~10⁸ Ω cm, respectively. The resistivity of kaolinite and montmorillonite were ~10¹² Ω cm. Bentonite showed the lowest electrical resistivity of ~10⁹ Ω cm among the clays because of the high cation exchange capacity of the material. The film surface morphologies and mechanical properties in the form of hardness and scratchability were also investigated.     

Modification of the electrical properties of polyimide by irradiation with 80 keV Xe ions

We modify the electrical properties of polyimide (PI) films by irradiation with 80 keV Xe ions. The surface resistivity of irradiated PI film at room temperature decreases remarkably from 1.2 × 10¹⁴ Ω/□ for virgin PI film to 3.15 × 10⁶ Ω/□ for PI film irradiated by 5.0 × 10¹⁶ ions/cm², and the temperature dependence of the resistivity of the treated films is well-fit using Mott's Equation. The irradiated PI film structure is studied using Raman spectroscopy, X-ray diffraction, and Rutherford Backscattering Spectrometry. The concentration of O in the irradiated layer decreases with increasing fluence, while the variation of N concentration is negligible. Graphite-like carbon-rich phases are created in the irradiated layers, leading to the modification of the electrical properties.     

Properties of multilayer gallium and aluminum doped ZnO(GZO/AZO) transparent thin films deposited by pulsed laser deposition process

Multilayer gallium and aluminum doped ZnO (GZO/AZO) films were fabricated by alternative deposition of Ga-doped zinc oxide(GZO) and Al-doped zinc oxide(AZO) thin film by using pulsed laser deposition(PLD) process. The electrical and optical properties of these GZO/AZO thin films were investigated and compared with those of GZO and AZO thin films. The GZO/AZO (1:1) thin film deposited at 400 °C shows the electrical resistivity of 4.18×10^?4 ωcm, an electron concentration of 7.5×10²⁰/cm³, and carrier mobility of 25.4 cm²/(V·s). The optical transmittances of GZO/AZO thin films are over 85%. The optical band gap energy of GZO/AZO thin films linearly decreases with increasing the Al ratio.     

Wear mechanism of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

The wear resistance and wear mechanism of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 100 A/cm² with shot number from one to ten are investigated by dry sliding wear tests. The cross-sectional microstructure and surface microhardness of the irradiated AZ31 magnesium alloys are examined by optical microscopy (OM) and Vickers tester, respectively. It is found that surface hardness increased with increasing shot number, from an original value of 570 MPa to a maximal value of 820 MPa with ten shots, and the wear rate of the samples irradiated with five and ten shots was about one order of magnitude less than that of the original sample. The transition from severe metallic wear to mild oxidative wear induced by HIPIB irradiation was identified through a combined analysis in surface morphology and chemical composition of wear tracks, mechanically mixed materials, wear debris and wear scars of counterface steel ball by using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA), which is mainly attributed to the significant increase in microhardness resulting from grain refinement on the irradiated surface.     

Effect of nickel content on the neutron irradiation embrittlement of Ni-Mo-Cr steels

The influence of nickel on the neutron irradiation embrittlement of Ni-Mo-Cr reactor pressure vessel (RPV) steels was investigated using alloys containing nickel in the range of 0.9–3.5 wt%. In all investigated alloys, the neutron irradiation with two dose conditions of 4.5 × 10¹⁹ neutron/cm² at 290 °C and 9.0 × 10¹⁹ neutron/cm² at 290 °C, respectively, increased the hardness and ductile-to-brittle transition temperature (DBTT). However, the increases of the hardness and DBTT resulting from the neutron irradiation were primarily affected by the irradiation dose that is closely related to the generation of irradiation defects, but not by the nickel content. In addition, a linear relationship between the changes in the hardness and DBTT subjected to the irradiation was confirmed. These results demonstrate that increasing the nickel content up to 3.5 wt% does not have a harmful effect on the irradiation embrittlement of Ni-Mo-Cr reactor pressure vessel (RPV) steels.     

Preparation and characterization of ZnO/Cu/ZnO transparent conductive films

ZnO/Cu/ZnO transparent conductive thin films were prepared by RF sputtering deposition of ZnO target and DC sputtering deposition of Cu target on n-type (001) Si and glass substrates at room temperature. The morphology, structure, optical, and electrical properties of the multilayer films were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), UV/Vis spectrophotometer, and Hall effect measurement system. The influence of Cu layer thickness and the oxygen pressure in sputtering atmosphere on the film properties were studied. ZnO/Cu/ZnO transparent conductive film fabricated in pure Ar atmosphere with 10 nm Cu layer thickness has the best performance: resistivity of 2.3×10-4 Ω·cm, carrier concentration of 6.44×1016cm-2 , mobility of 4.51cm2·(V·s)-1 , and acceptable average transmittance of 80 % in the visible range. The transmittance and conductivity of the films fabricated with oxygen are lower than those of the films fabricated without oxygen, which indicates that oxygen atmosphere does not improve the optical and electrical properties of ZnO/Cu/ ZnO films.     

Effect of irradiation by nitrogen and helium ions on the structure and electrical resistance of nanocrystalline V-N coatings

The results of studies of the radiation damage of V-N coatings irradiated by nitrogen and helium ions with energies of 40 and 20 keV, respectively, are presented. The coatings have been obtained using a technique of ion-stimulated deposition and represented a nanocrystalline composite with grain sizes of 20–50 nm, intergrain junctions of which contained voids with sizes of 3–6 nm. It has been shown that during irradiation, the electrical resistivity of such objects increases. No visible structure changes are observed up to doses of 7–8 × 10¹⁶ ion/cm². A further increase in the dose leads to changes in the void structure and to a transformation of the closed porosity to an open one. It has been shown that the system of arising channels creates conditions for evolving the accumulating helium and preserving the integrity of the coating.     

Effect of neutron irradiation on the properties of the FeSe compound in the superconducting and normal states

The influence of atomic disorder induced by irradiation with fast neutrons on the properties of normal and superconducting states of polycrystalline samples of FeSe has been studied. The irradiation with fluences of fast neutrons up to 1.25 × 10²⁰ cm^?2 at the irradiation temperature T _irr ?? 50°C leads to relatively small changes in the temperature T _c of the superconducting transition and in the electrical resistivity ??₂₅ at 25 K. This behavior is related to the relatively low concentration of radiation defects arising at a given irradiation temperature, which is a consequence of a specific crystal structure of FeSe, which is more simple as compared to other layered compounds of this class.     

Effects of dopant content on optical and electrical properties of In<Subscript>2</Subscript>O<Subscript>3</Subscript>: W transparent conductive films

The In2O3:W (IWO) films with different W content were deposited on glass substrate using direct current sputtering method. The structure, surface morphology, and optical and electrical properties were investigated. Results showed that both the carrier concentration and carrier mobility were increased with the doping of W. The IWO film with the lowest resistivity of 1. 0× 10-3 Ω· cm, highest carrier mobility of 43. 7 cm2. W-1. s-1 and carrier concentration of 1. 4× 1020 cm-3 was obtained at the content of 2. 8 wt. ％. The average optical transmittance from 300 nm to 900 nm reached 87. 6％.     

Effect of substrate rotation speed on structure and properties of Al-doped ZnO thin films prepared by rf-sputtering

Al-doped ZnO (AZO) thin films were deposited on glass substrates by rf-sputtering at room temperature. The effects of substrate rotation speed (ω_S) on the morphological, structural, optical and electrical properties were investigated. SEM transversal images show that the substrate rotation produces dense columnar structures which were found to be better defined under substrate rotation. AFM images show that the surface particles of the samples formed under substrate rotation are smaller and denser than those of a stationary one, leading to smaller grain sizes. XRD results show that all films have hexagonal wurtzite structure and preferred c-axis orientation with a tensile stress along the c-axis. The average optical transmittance was above 90% in UV-Vis region. The lowest resistivity value (8.5×10^?3 Ω·cm) was achieved at ω_S=0 r/min, with a carrier concentration of 1.8×10²⁰ cm^?3, and a Hall mobility of 4.19 cm²/(V·s). For all other samples, the substrate rotation induced changes in the carrier concentration and Hall mobility which resulted in the increasing of electrical resistivity. These results indicate that the morphology, structure, optical and electrical properties of the AZO thin films are strongly affected by the substrate rotation speed.     

Preparation and properties of tungsten-doped indium oxide thin films

Tungsten-doped indium oxide (IWO) thin films were deposited on glass substrate by DC reactive magnetron sputtering. The effects of sputtering power and growth temperature on the structure, surface morphology, optical and electrical properties of IWO thin films were investigated. The thickness and surface morphology of the films are both closely dependent on the sputtering power and the substrate temperature. The transparency of the films decreases with the increase of the sputtering power but is not seriously influenced by substrate temperature. All the IWO thin film samples have high transmittance in near-infrared spectral range. With either the sputtering power or the growth temperature increases, the resistivity of the film decreases at the beginning and increases after the optimum parameters. The as-deposited IWO films with minimum resistivity of 6. 4× 10-4 Ω·cm were obtained at a growth temperature of 225 ℃ and sputtering power of 40 W, with carrier mobility of 33. 0 cm2· V-1·s-1 and carrier concentration of 2. 8× 1020 cm-3 and the average transmittance of about 81％ in near-infrared region and about 87％ in visible region.     

Laser Surface Treatment of Stellite 6 Coating Deposited by HVOF on 316L Alloy

This research aimed to study the effects of laser glazing treatment on microstructure, hardness, and oxidation behavior of Stellite 6 coating deposited by high velocity oxygen fuel (HVOF) spraying. The as-sprayed Stellite 6 coating (ST-HVOF) was subjected to single-pass and multiple-pass laser treatments to achieve the optimum glazing parameters. Microstructural characterizations were performed by x-ray diffractometry and field emission scanning electron microscopy equipped with energy-dispersive spectroscopy. Two-step optimization showed that laser treatment at the power of 200 W with a scan rate of 4 mm/s causes a surface layer with a thickness of 208 ± 32 µm to be remelted, while the underlying layers retain the original ST-HVOF coating structure. The obtained sample (ST-Glazing) exhibited a highly dense and uniform structure with an extremely low porosity of ~0.3%, much lower than that of ST-HVOF coating (2.3%). The average microhardness of ST-Glazing was measured to be 519 Hv_0.3 indicating a 17% decrease compared to ST-HVOF (625 Hv_0.3) due to the residual stress relief and dendrite coarsening from submicron size to ~3.4 µm after laser treatment. The lowest oxidation mass gain was obtained for ST-Glazing by 2 mg/cm² after 8 cycles at 900 °C indicating 52 and 84% improvement in oxidation resistance in comparison to ST-HVOF and bare 316L steel substrates, respectively.     

Influence of Nd-Co Substitution on Structural,Electrical, and Dielectric Properties of X-Type Hexagonal Nanoferrites

A series of single phase X-type hexagonal ferrites with concentration Sr_2?x Nd _x Ni₂Fe_28?y Co _y O₄₆ (x = 0.02, 0.04, 0.06, 0.08, 0.10 and y = 0.1, 0.2, 0.3, 0.4, 0.5) has been prepared by sol-gel method sintered at 1250 °C for 6 h. The x-ray diffraction analysis reveals the single phase of X-type hexagonal ferrites. The particle size was calculated by using SEM and TEM. The ferrite substituted with Nd³⁺ and Co²⁺ has average particle size in the range of 40-50 nm. The room temperature electrical resistivity experiences the significant enhancement from a value of 1.1 × 10⁷ to 2.03 × 10⁸ Ωcm with the increase in Nd³⁺ and Co²⁺ concentration. The dielectric constant exhibits high value at low frequencies and decreases with the increase of frequency. The tangent dielectric loss shows the abnormal behavior which can be explained on the basis of hopping between the Fe²⁺ and Fe³⁺ ions on octahedral sites. The maximum value of tangent loss at low frequencies reflects the application of these materials in medium frequency devices (MF).     

Structural Relaxation and Nanocrystallization-Induced Laser Surface Hardening of Fe-Based Bulk Amorphous Alloys

Amorphous metallic alloys or bulk metallic glasses are emerging as promising materials for a range of structural, microelectromechanical systems, and biomedical applications. With the recent developments in spark plasma sintering and superplastic forming of the amorphous alloys, it is likely that the amorphous alloys will find a place in new applications. In this article, surface hardening of spark plasma sintered Fe₄₈Cr₁₅Mo₁₄Y₂C₁₅B₆ bulk amorphous alloys using a continuous-wave Nd:YAG laser is reported. Depending on the processing parameters, the laser surface irradiation causes structural relaxation (enhanced medium-range ordering and/or annihilation of excess free volume) and nanocrystallization of hard carbides (M₂₃C₆ and M₇C₃), resulting in surface hardening. Detailed investigations on the thermal effects, microstructural modifications, and hardness improvements due to laser surface irradiation with laser fluence in the range of 1.77–2.36 J/mm² are presented. An increase in hardness in the range of 1360–1560 HV for laser surface-treated alloys compared to 1200 HV for as-sintered alloys over a hardening depth of about 50–80 µm is observed.     

Low-energy ion beam treatment of α-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>(0001) and improvement of photoluminescence of ZnO thin films

A low energy N₂ ^? ion beam impinged on a α-Al₂O₃(0001) single crystal surface in the range of fluence 5×10¹⁵/cm²?1×10¹⁸/cm² at room temperature. After ion bombardment, chemical bonding on the modified sapphire surface was investigated by x-ray photoelectron spectroscopy. Below a fluence of 1×10¹⁵/cm², only a non-bonded N1s peak at the binding energy 398.7 eV was found, but further irradiation up to 2×10¹⁷/cm² induced Al?O?N bonding at around 403 eV. The occurrence of Al?N bonding was identified at ion fluence higher than 5×10¹⁷/cm² at 396.6 eV. II–VI ZnO thin films were grown on an untreated/ion-beam-induced sapphire surface by pulsed laser deposition (PLD) for the investigation of the modified-substrate effect on photoluminescence. The ZnO films grown on modified sapphire containing Al?O?N bonding only, and both Al?O?N and Al?N bonding showed a significant reduction of the peak related to deep-level defects in photoluminescence. These results are explained in terms of the formation of Al?N?O and Al?O?N layers and relaxation of the interfacial strain between Al₂O₃ and ZnO.