Additive manufacturing (AM) using recycled Ti-6Al-4V (Ti64) feedstock material from wrought waste streams is a novel process that can reduce the overall energy cost and carbon (CO2) footprint when compared to primary-production routes. The potential contamination of recycled feedstock material (e.g. C, O, N and Fe) can affect the microstructure and mechanical properties of the component. In this work, a Ti64 test wall built using wire arc AM (WAAM) was studied, where the top half only was contaminated by N through the shielding gas during deposition. This allowed a direct comparison of Ti64 WAAM material with high and low N content, deposited under otherwise identical conditions, to replicate the worst-case scenario of N contamination from using recycled swarf. The hardness of the N-contaminated section was found to be 25% higher than the uncontaminated section of the wall, demonstrating the N solid solution strengthening in Ti64. The room temperature transformed microstructure was found to have a 25% coarser alpha-lath thickness, which was proposed to be an effect of the AM cyclical heating and increasing of the beta-transus temperature due to a higher level of N. Additionally, the outer layer of the N-contaminated sample section was found to have a refined parent beta grain structure.

As-deposited Wire-Arc Additive Manufactured (WAAM) Ti-6Al-4V parts typically contain large columnar beta-grains on a centimetre scale, with a strong < 001 > fibre texture, leading to anisotropic mechanical properties and unacceptable scatter in damage tolerance. Inter-pass deformation, introduced by the application of Ultrasonic Impact Peening (UIP) across each added layer, has been shown to be effective in refining the beta-grain structure and achieving a weaker texture. The depth of deformation and the grain refinement mechanism induced by UIP have been investigated by combining advanced electron backscatter diffraction (EBSD) characterization with a 'stop action' observation technique. UIP facilitates a similar refinement mechanism and nearly the same depth of deformation as conventional machine hammer peening, with the advantages of a much higher strain rate, lower peak force, and two orders of magnitude lower impact energy, making it a faster and more economical process. beta recrystallization is seen within the deformation zone during re-heating through the alpha -> beta transition. Although new recrystallized beta-grains formed in the UIP surface-deformed layer to a shallower depth than that of remelting, recrystallization initiated ahead of the melt pool and the recrystallized grains grew downwards to a greater depth before remelting. These refined grains were thus able to survive and act as nucleation sites at the fusion boundary for epitaxial regrowth during solidification, greatly refining the grain structure.

Optoelectronic features of Zn1-xGdxO (x = 0.01, 0.03 and 0.05) nanorods were explored through a series of optical characterizations. The presence of different functional groups and vibrational modes in the samples were observed through Fourier-transform infrared (FTIR) and Raman characterizations, respectively. The characteristic stretching vibrational modes of Zn–O and Gd-Zn–O were probed through FTIR. The peaks appeared in the Raman spectra are associated with the characteristics of ZnO samples. The bandgap of the ZnO sample decreased from 3.19 to 3.16 eV with increasing Gd doping concentration as evident from UV–Visible spectroscopy. Photoluminescence measurement showed the signature of intrinsic defects and the colour emission of the samples shifted more towards the green emission region with Gd doping concentration. Our study demonstrates the possible usefulness of the materials in commercial UV lighting applications.

The titanium alloy Ti–6Al–2Sn–4Zr–2Mo–0.1Si (Ti6242) has been deposited for the first time by a directed energy deposition process using a wire and arc system— i.e., wire-arc additive manufacturing (WAAM)—with and without inter-pass machine hammer peening, and its microstructure investigated and compared to the more commonly used alloy Ti–6Al–4V (Ti64). The application of inter-pass machine hammer peening—where each added layer was deformed before deposition—successfully refined the strongly textured, coarse, columnar β -grain structure that is commonly seen in α + β titanium alloys, producing a finer equiaxed grain structure with a near-random α texture. The average grain diameter and texture strength decreased with the peening pitch. When Ti6242 was deposited under identical conditions to Ti64, by switching the alloy feed wire in-situ, the refined β -grain size decreased across the alloy-to-alloy transition reaching on average 25 pct less in Ti6242 than in Ti64. A similar 25 pct scale reduction was also found in the Ti6242 α -lath transformation microstructure. This comparatively greater microstructure refinement in Ti6242 was attributed to the dissimilar alloying elements present in the two materials; specifically, molybdenum, which has a lower diffusivity than vanadium and led to slower β -grain growth during reheating as well as a finer transformation microstructure.

Surfactant free wet chemical route is employed to synthesize Zn1-xCexO ( x = 0.01, 0.03 and 0.05) nanorods. Ef-fects of Ce doping on the microstructural, optical and magnetic properties of the ZnO nanorods are reported. X-ray diffraction study revealed the hexagonal wurtzite phase of ZnO with formation of secondary phase corresponding to CeO2. Nanorod nature of the samples was confirmed from field emission scanning electron microscope micro-graph. The systematic decrease of band gap from 3.192 to 3.177 eV with increasing Ce doping concentration from 1 to 5% was evidenced from UV-Visible characterization. The photoluminescence spectral feature confirms the presence of intrinsic defects like zinc, oxygen vacancies etc. The different functional groups were identified from Fourier transform infrared spectra. A very weak ferromagnetic ordering was observed in all the samples at room temperature. Our study suggested that the synthesized Ce doped ZnO nanorods could be useful for optical device applications in the UV region.

Surfactant and organic solvents-based SnO2 rods and SnO2/rGO, SnO2/MWCNTs composite materials were synthesized by microwave-assisted hydrothermal process. Powder X-ray diffraction analysis revealed the rutile phase formation. Surface morphology of the prepared samples and their chemical compositions were investigated by SEM and EDS, respectively. Lithium ion batteries (LIBs) were fabricated from synthesized SnO2 rods and composites SnO2/rGO, SnO2/MWCNTs as anode materials and it revealed promising initial discharge capacity of 1426 mAh g−1 and 1575 mAh g−1, 1189 mAh g−1 respectively. Electrochemical studies showed that the discharge capacities retained even after 100th cycle were found to be 171 mAh g−1, 351 mAh g−1 and 214 mAh g−1 even at a high current density of 500 mA g−1, with high coulombic efficiency for SnO2 rods and SnO2/rGO, SnO2/MWCNTs composites, respectively. These findings are better than the commercially used graphite as anode material. Further, electrochemical impedance spectra of the fabricated LIBs having SnO2/rGO and SnO2/MWCNTs composites used as anode material showed less charge transfer resistance as compared to bare SnO2 rods. Due to low charge transfer resistance, improved electrical conductivity and the large surface area of rGO nanosheets, the SnO2/rGO composite exhibited better electrochemical performance when compared with the bare SnO2 rods and SnO2/MWCNTs composite.

Nanoparticles of Zn1-xLaxO (x = 0, 0.01, 0.03 and 0.05) were successfully synthesized by a cost-effective chemical method. The influences of La on the microstructural, optical, antimicrobial and magnetic properties of these ZnO nanoparticles were investigated. XRD studies revealed the presence of hexagonal wurtzite phase of ZnO without any impurity. The samples possess nanorod morphology as confirmed by FESEM and TEM analysis. The band gap of ZnO nanorods increased from 3.25 to 3.27 eV with increasing La concentration from 0% to 5%. The presence of various defects in our samples were identified by PL spectroscopy. Magnetic studies exposed the signature of ferromagnetism in all the samples at 300 K. The magnetization of ZnO nanorods is significantly enhanced by La doping. A maximum values of magnetization was observed for 1% La doped ZnO sample which is similar to 6 times more than for a pure ZnO nanorods. The contributions of oxygen vacancies towards the observed ferromagnetism were confirmed. The origin of ferromagnetism was enlightened on the basis of results of a BMP model. In vitro bioassays showed that synthesized nanorods exhibited narrow-spectrum antibacterial activity against Staphylococcus aureus that compared well with commercial ZnO, nanoparticles (Sigma). Furthermore, the synthesized nanorods when tested for toxicity against Caenorhabditis elegans, but show only low toxicity at 100 pg/mL. Toxicity in zebrafish was also limited. Based on their multifunctional properties, we believe that the synthesized ZnO nanorods could be beneficial for optical device applications in the UV range, spintronic devices, as well as for biomedical purposes. (C) 2021 Elsevier B.V. All rights reserved.

Properties of chemically synthesized Zn1_xGdxO (x = 0.01, 0.03 and 0.05) nanorods were explored through microstructural, morphological, toxicity and magnetic characterizations. Hexagonal wurtzite structure of all the samples without any impurity phases was confirmed by X-ray diffraction characterization. The micrographs of transmission electron microscope and field emission scanning electron microscope revealed the rod shape morphology of the samples. A systematic evolution of room temperature ferromagnetism of ZnO nanorods with increasing Gd doping content was observed. Gd doped ZnO nanorods showed narrow-spectrum antibacterial activity against the most opportunistic Gram-positive pathogen bacterium, S. aureus as compared to commercial ZnO. From cytotoxicity assessment with Caenorhabditis elegans and Danio rerio, the samples were non-toxic or showed little toxicity at the highest concentration tested (100 mu g/mL) except for 1% Gd doped ZnO. Our study demonstrates the possible usefulness of the materials in spintronic, magnetic media device as well as bio-medical applications.

Ni1-xZnxO nanoparticles were synthesized by wet-chemical route. XRD characterization of these samples indicated that Zn doping in NiO neither induces structural phase transformation nor any secondary phase. Rietveld refinement of XRD data indicated that the lattice parameter of NiO increases with increasing of Zn doping concentration. TEM analysis confirms the reduction of agglomeration and shape transformation from irregular to almost spherical shape up on Zn doping in NiO. Raman study combined with photoluminescence study suggested that these materials could be useful for optical applications. Magnetic characterization of Ni1-xZnxO samples indicates that all samples show weak ferromagnetism at room temperature with the persistence of unsaturation behavior even up to very high magnetic field. Our study indicated that the synthesized samples could be useful for UV emission device, magnetic random access memory and data storage applications.

Heterojunction of ZnO/NiO films each of thickness 100 nm was irradiated with 200 MeV Ag ions at room temperature. The films were deposited on Si(100) by PLD method. Evolution of electrical property with ion fluence probed though in-situ I-V measurement showed that ion irradiation suppressed the rectifying nature of the pristine heterojunction and the junctions became Ohmic at high ion fluences. The reverse biased leakage current showed a monotonic increase, while the ideality factor of this diode structure, showed an increase followed by a decrease and then saturation with increasing irradiation fluence. The mechanism of electrical conduction seems to follow the power law model. The exponential decrease of barrier height with ion fluence could be attributed to the implantation of ion track in the sample. The close matching of the radius of ion tracks obtained from various parameters of the heterojunction suggests that mixing at the interface of ZnO/NiO layer lead to the variation of these parameters with ion fluence.

NiO/ZnO heterojunction deposited on Si(100) substrate by evaporation method were irradiated with 120 MeVAg ions. The effects of ion irradiation on various properties of the heterojunction were studied. Crystallinity of NiO layer improved due to irradiation at the fluence of 3 x 10(11) ions cm(-2) as revealed by the increase in grazing incidence X-ray diffraction (GIXRD) peak intensity. Further irradiation reduced the intensity of GIXRD peaks but could not suppress it completely even at the highest fluence (1 x 10(13) ions cm(-2)), where the whole bilayer is expected to be covered with ion tracks. This observation indicated that the columnar region around the ion path is not completely a morphized, but its crystallinity is reduced. Evolution of the area under GIXRD peaks with ion fluence gave radius of this modified columnar region as similar to 4.9 nm. The peaks of ZnO were not clearly evident in the GIXRD pattern. However a weak peak due to ZnO could be seen in the Raman spectra, which also did not completely vanish even at the highest fluence of irradiation. The bilayer sample irradiated at a fluence of 1 x 10(12) ions cm(-2) showed the highest switching ratio, which could be due to the thermal spike induced diffusion of ions across the NiO/ZnO junction.

Evolution of surface features and optical band gap of ZnO thin films deposited on different NiO/Si(100) are reported. In order to create different initial microstructure, we first deposited NiO film on Si(100) at 3 different temperatures (400°C, 650°C, and 700°C) by pulsed laser deposition. These NiO/Si(100) films are used as substrate for the deposition of ZnO films. Combining the results obtained from grazing incidence X‐ray diffraction, atomic force microscope, and UV‐Visible characterization, our study indicated that the microstructure of the substrate takes the important role in dictating properties of the film. Our study also indicated that one needs to choose appropriate synthesis condition to achieve good quality ZnO films.

ZnO/NiO thin films, each of thickness 100 nm, were deposited on Si(100) substrate by pulsed laser deposition method. The resulting heterojunction, ZnO/NiO/Si, was irradiated by 120 MeV Au9+ ions and characterized by grazing incidence X‐ray diffraction (GIXRD), Raman spectroscopy, and atomic force microscopy (AFM). The GIXRD confirmed the presence of both NiO and ZnO in the samples. Ion irradiation induced suppression of crystalline nature, and the recrystallization of the same occurred at the fluence of 1 × 1013 ions cm−2. The occurrence of most intense band at 302 cm−1 in Raman spectra corresponds to the symmetric stretching vibration of ZnO. The linear shift of stretching mode of ZnO with ion fluence could be associated with the effect of compressive stress in the material. AFM analysis of the films indicated that the rms roughness increased when the film is irradiated at a fluence of 1 × 1012 ions cm−2. Beyond this fluence, the value of roughness decreased up to fluence of 1 × 1013 ions cm−2 and increased thereafter. To see the effect of the stress of buffer layer on the surface layer, we calculated the stress for NiO layer with ion fluence form the lattice parameter. Comparing the stress of buffer layer with roughness of surface layer at the given fluence, we can say that the compressive stress in the buffer layer could possibly control the roughness of the surface layer.

We synthesized Ni1-xFexO (x = 0, 0.01 and 0.02) nanoparticles by chemical co-precipitation method and studied the effect of Fe on the optical properties of NiO. UV-visible characterization of these samples indicated that the optical band gap of NiO decreased from 3.65 to 3.43 eV when the doping concentration increased from x = 0 to x = 0.02. Since NiO is a p-type material and the holes are expected to populate at the top of the valence band due to Fe doping which can cause the band gap shrinkage as is seen in our case. The refractive index and electron polarizability with Fe doping concentration in NiO have been determined from the optical band gap. Both refractive index and electron polarizability follow opposite trend as compared to the energy gap as a function of Fe doping concentration.

BiFeO3 thin films deposited by sol-gel spin coating method were irradiated by 200 MeV Ag ions. Irradiation induced modification of the microstructure of the films was studied by X-ray diffraction (XRD), micro Raman, UV-Visible spectroscopy, atomic force microscopy and current-voltage (I-V) measurements. XRD analysis revealed that the pristine films are crystalline BiFeO3 phase. Ion irradiation led to fragmentation of the crystallites in the films up to the fluence of 3 x 10(12) ions cm(-2) and amorphization beyond this fluence. The crystallite size showed a monotonic decrease with increasing ion fluence. XRD peaks shifted to lower angles with increasing ion fluence, thus indicating irradiation induced increase of lattice parameter. Irradiation induced lattice expansion is understood on the basic of reduction of crystallite size. In agreement with this observation, the optical band gap showed blue shift with increasing ion fluence. I-V measurement showed a three orders of magnitude decrease of the leakage current density with increasing ion fluence up to 3 x 1012 ions cm(-2). This dramatic decrease of leakage current density is explained on the basis of widening of the band gap, which is a direct consequence of SHI induced crystallite size reduction.

BiFeO 3 (BFO) thin films of thickness about 800 nm deposited on Si (100) substrates by sol–gel spin coating method were irradiated by 200 MeV Ag ions. Modification of structure and surface morphology of the films under irradiation was studied using glancing incidence X-ray diffraction (GIXRD) and atomic force microscope (AFM). Fluence dependence of GIXRD peak intensity indicated formation of 10 nm diameter cylindrical amorphous columns in crystalline BFO due to 200 MeV Ag ion irradiation. AFM analysis indicated that the pristine film consists of agglomerated grains with diffuse grain boundary. Irradiation led to reduced agglomeration of the grains with the formation of sharper grain boundaries. The rms roughness ( σ rms ) estimated from AFM analysis increased from 6·2 in pristine film to 12·7 nm when the film irradiated at a fluence of 1 × 10 11 ions cm − 2 . Further irradiation led to decrease of σ rms which finally saturated at a value of 7–8 nm at high ion fluences. The power spectral density analysis indicated that the evolution of surface morphology of the pristine film is governed by the combined effect of evaporation condensation and volume diffusion processes. Swift heavy ion irradiation seems to increase the dominance of volume diffusion in controlling surface morphology of the film at high ion fluences.

Temperature dependent resistivity of YBa2Cu3O7−y (YBCO) thick films irradiated with 200MeV Ag ions has been investigated. The YBCO thick films were prepared by solid state diffusion reaction technique. In contrast to the general perception that the energetic ion induces defects and disorders, which lead to decrease of Tc and increase of normal state resistivity in a superconductor, 200MeV Ag ions in the present case led to an increase in Tc and decrease in normal state resistivity at low ion fluence (1011 ions cm−2) in YBCO. At this fluence, the electronic energy loss, Se induced amorphous ion tracks are well separated from each other and hence are not expected to influence the Tc. The observed changes in transport properties is explained as being caused by irradiation-induced chain oxygen ordering of the oxygen defects in the CuO chains. Subsequent increase of irradiation fluence leads to decrease of Tc and increase of normal state resistivity.

In the present study, we report the modification of pulsed laser deposited c-axis oriented thin films of YBa2Cu3O7-y (YBCO) in a cylindrical region around the path of swift heavy ions (SHIs). Our in situ temperature-dependent resistivity measurement and in situ low-temperature X-ray diffraction (XRD) study on YBCO irradiated at liquid nitrogen temperature with 200 MeV Ag ions shows that the SHI-induced secondary electrons selectively create point defects at CuO basal chains of YBCO. Beyond a critical fluence (similar to 10(12) ions/cm(2)), the radially strained region around the amorphous latent tracks estimated from full width at half-maximum of (00l) XRD peaks tends to overlap, and a two-step superconducting transition evolves instead of a single transition in the in situ resistivity measurement.