Powder Target Research Articles

The Difference between the Spectra of Parametric X-Ray Radiation from Powder Targets and Textured Polycrystals

The Difference between the Spectra of Parametric X-Ray Radiation from Powder Targets and Textured Polycrystals

Room-temperature tuning of mid-infrared optical phonons and plasmons in W-doped VO2 thin films

The development of mid-infrared nanophotonics relies on the availability of new materials combining metal- and insulator-like optical features. We systematically studied the phase transition of thermochromic vanadium dioxide (VO2) using substitutional tungsten doping at room temperature. Our results reveal that vanadium dioxide thin films, doped with tungsten and grown via pulsed laser deposition techniques on sapphire substrates, can be precisely engineered to exhibit tailored infrared phonon and plasmon polaritonic responses. By controlling the extent of tungsten concentration, starting from VO2-WO3 cold-pressed powder targets, we demonstrate the ability to continuously adjust both the amplitude and frequency of optical phonon resonances. Furthermore, we observe tunable free-electron response due to varying tungsten concentrations. The adopted fabrication technique makes it possible to create multilayer structures by alternating layers with different concentrations of tungsten. Our results pave the way for the development of tunable mid-infrared metamaterial devices operating at room-temperature.

Functional modification of TC4 by Cu-containing titanium dioxide films

To improve the biological fouling and corrosion resistance of Ti6Al4V (TC4) in marine environments, copper-containing titanium dioxide (TiO2(Cu)) films were prepared by magnetron sputtering TiO2(Cu) powder targets. The morphologies of the films showed that they became rough and coarse from 1.6 nm of the TiO2 film to approximately 9 nm of the TiO2(Cu) films, which might be owing to the increase in the deposition rates from 1.33 to 2.08 nm/min. No diffraction orientations of the TiO2 and Cu phases were found compared to those of the TiO2(Cu) powder. Ti, O, and Cu were detected using X-ray photoelectron spectroscopy to confirm the composition of the films. The ratio of Cu2+ increased as the Cu content of the films increased, whereas that of Cu/Cu + scarcely changed. The TiO2 and TiO2(Cu) films exhibited photocatalytic effects and their photocatalytic intensities decreased as the Cu content increased. Hydrophobicity was enhanced by the addition of Cu to the film. The antibiological fouling effect of the TiO2(Cu) films remained unchanged as the Cu/Ti ratio varied. Compared with those of TC4, the corrosion current densities of the TiO2(Cu) films decreased by one order of magnitude and the corrosion potentials increased by 350 mV in artificial seawater, indicating that the corrosion resistance of TiO2(Cu)/TC4 was improved. Importantly, Cu was in abundance in the films for both antibiological and corrosion resistance functions owing to the saturated ratio of Cu/Cu+ irrespective of the Cu/Ti ratio in the films.

Post-fabrication adjustment of metalloid Mg–C-graphene nanoparticles via Pulsed Laser Ablation for paper electronics and process optimisation

Metalloid nanoparticles (MNPs) possess unique physicochemical properties but are challenging to create through biological or chemical routes. Using Pulsed Laser Ablation in Liquid (PLAL), Mg–C MNPs are fabricated from powders. The produced nanocolloids were ablated after the target was removed to tailor the particle size. MNPs with a mean size 300 nm could be reduced to 60 nm. Alternatively, MNPs with a mean size of 60 nm could be increased to 90 nm. The increase/decrease in size is controlled by the laser processing parameters and showcases the ability of PLAL for real-world applications that require meticulous control of size. The as-fabricated nanocolloids were successfully inkjet printed on paper, achieving a low resistivity of 75 Ω/square after 60 prints, highlighting their potential in printed electronics. To address a historical research gap, this article explored the impact of PLAL processing parameters, including fluence (1–2 J/cm2), pulse width (0.2–0.9 ns), repetition rate (10–20 kHz), and pH, factors often overlooked which is partly limiting applications. The influence of powder vs rod target on the PLAL process was addressed revealing that powders produce better size control and are easier to handle but they produce lower colloid concentrations.

Crystal Al-Doped ZnO Thin-Film Preparation by Sputtering Deposition using a Mixed-Powder Target

Al-doped ZnO films were prepared by sputtering deposition using mixtures of Al2O3 and ZnO powder targets. The film quality depended on the conditions of the target powder. The deposition rate, crystallinity, and transparency of films prepared with new, pressed powder targets were higher than those prepared with used, nonpressed powder targets. In addition, we found that pressurizing the new-powder target and increasing the substrate temperature resulted in thin films with high transparency and electrical conductivity

Indium-gallium-zinc oxide thin-film preparation via single-step radio frequency sputter deposition using mixed-oxide powder targets

Indium-gallium-zinc oxide thin-film preparation via single-step radio frequency sputter deposition using mixed-oxide powder targets

Abrasion-resistant, transparent, conductive In2O3@SiO2 films

External smart wearable films requires that films have good transparency, electrical conductivity, wear resistance and corrosion resistance, but the research on some issues have not been discussed anywhere. The composite In2O3@SiO2 functional films intended for smart wearable devices were synthesised via closed-field unbalanced magnetron sputtering from a powder target. This study investigated the impact of the Si:In atomic ratio in the target on the films' transparency, conductivity, resistance to sweat corrosion, and wear resistance, while elucidating the underpinning mechanisms. Results revealed that the film roughness declined from 4.41 to 1.5 nm with increasing Si:In ratio, and the preferred orientations observed in the pure In2O3 film were lost upon the incorporation of SiO2 particles. The films maintained a visible-region transmittance of 82–85%. However, the band gaps and sheet resistances increased from 3.78 to 4.3 eV and 52–2740 Ω·sq−1, respectively. The In2O3@SiO2 film with 10 at. % SiO2 demonstrated relative structural integrity, and minimal changes in optical and electric properties after acid treatment. Films with 15 at. % SiO2, both with and without exposure exhibited pitting and peeling, with changes in transmittance and sheet resistance of 14.44% and 13.08%, respectively. The alkali-treated films displayed minimal changes. The pure In2O3 film failed after 30 h of vibration. After 48 h of vibratory wear, the In2O3@SiO2 films' transmittance decreased to approximately 72%, and sheet resistances increased to 2.5 KΩ for 10 at. % SiO2 and 23 KΩ for 15 at. % SiO2. The evenly dispersed SiO2 nanodots of the In2O3@SiO2 film with 10 at. % SiO2 showed superior overall properties, including transparency, conductivity, sweat corrosion resistance, and wear resistance, attributed to the ‘maze effect’ obstructing corrosion pathways and the ‘mosaic pattern’ enhancing the abrasive properties.

Creation of crystal structure reproducing X-ray diffraction pattern without using database

When a sample’s X-ray diffraction pattern (XRD) is measured, the corresponding crystal structure is usually determined by searching for similar XRD patterns in the database. However, if a similar XRD pattern is not found, it is tremendously laborious to identify the crystal structure even for experts. This case commonly happens when researchers develop novel and complex materials. In this study, we propose a crystal structure creation scheme that reproduces a given XRD pattern. We employed a combinatorial inverse design method using an evolutionary algorithm and crystal morphing (Evolv&Morph) supported by Bayesian optimization, which maximizes the similarity of the XRD patterns between target one and those of the created crystal structures. For sixteen different crystal structure systems with twelve simulated and four powder target XRD patterns, Evolv&Morph successfully created crystal structures with the same XRD pattern as the target (cosine similarity 99% for the simulated ones and >96% the experimentally measured ones). Furthermore, the present method has merits in that it is an automated crystal structure creation scheme, not dependent on a database. We believe that Evolv&Morph can be applied not only to determine crystal structures but also to design materials for specific properties.

Detonation Technology in Producing Metal–Ceramic Powder Targets for Magnetron Sputtering

Detonation Technology in Producing Metal–Ceramic Powder Targets for Magnetron Sputtering

Bimetallic BaTiO3 and Cu nanoparticle synthesis via pulsed laser ablation in liquid of powder targets

Laser processing has become a viable method of synthesising bimetallic and biomolecule-free nanoparticles. Laser processing enable for different materials to be processed via the same laser system with ease, unlike chemical and biological methods that require special equipment/organisms for each material. The objective of this paper is to study the laser processing of powders for the fabrication of nanoparticles of various types, shapes, sizes and concentration. A Nd:YAG 1064 nm laser system was used to perform ablation processes of Cu and BaTiO3 powders under isopropyl alcohol, hydrochloric acid and ammonium buffer solution. This produced nanoparticles of various shapes including rods, spheres and pyramids and various sizes (14–280 nm). The effect of the laser processing parameters such as hatch spacing (10 or 30 μm) and scan speed (2 or 3 m/s) were examined. These processing parameters are seldom studied in the literature. Furthermore, this paper describes a way to produce nanoparticles from powder targets instead of the conventional rod, plate or thin film targets that are difficult to reuse. However, powders are compatible with a limited number of liquids than rods, plates and thin films and this issue is addressed herein.

Preparation of Ti and Fe Composition Gradient Thin Films by Sputtering with Mixed Powder Targets

Preparation of Ti and Fe Composition Gradient Thin Films by Sputtering with Mixed Powder Targets

Production of powder targets for neutron-induced cross section measurements

Nuclear powder targets for neutron-induced cross section measurements were prepared by pressing. The choice of the production technique was related to the type of nuclear experiment and the quality of the powder. This paper describes the production process of unsintered compacts of 94Mo, 95Mo, 96Mo metal powders and 239PuO2 powder with a thickness as low as possible by uniaxial pressing of powders. Special attention goes to the difficulties encountered during the preparation process of 239PuO2 pellets. Investigation on the presence of impurities and so the quality of the PuO2 material was performed by scanning electron microscopy with energy dispersive X-ray spectroscopy, by inductively coupled plasma mass spectrometry, X-ray diffraction and by thermal analysis.

Sputtering Deposition With Low Cost Multi-Element Powder Targets

Sputtering Deposition With Low Cost Multi-Element Powder Targets

Probing yields and angular distributions of Be(d,n) neutrons with novel target of compressed beryllium-powder

A comprehensive study was conducted in the Cyclotron laboratory at National Research Tomsk Polytechnic University on the use of a new type of target utilized in the production of fast-neutrons. The flux and spectra of the fast-neutrons emitted by a novel target of compressed beryllium powder were studied. The neutron angular distribution was measured using Fe and Al foils as detectors in different angular situations of the target relative to the incident deuteron beam. It was found that there are some discrepancies in the neutron flux at 0° degree for the detectors, up to about 20% for different target-beam angle. Likewise, the flux of neutrons in the energy range between 1 and 6 MeV make up about 83% of the total flux. Compering with previous works using solid target, we found an increase of nearly twice the yield of fast neutrons. And there is a probability that increase would rise steadily as the deuteron energies exceed 12 MeV as was the case in our work. The results of this study are new and promising and we can obtain a relatively greater neutron yield when using a compressed powder target. This is reflected positively on many applications that use fast-neutron beams, such as radiotherapy, radioactive isotopes, and even nuclear fusion experiments, among others.

Powder Metallurgy Route for the Synthesis of Multiprincipal Element Alloys Sputtering Targets

Sputter deposition of multiprincipal element alloys (MPEAs) is a relatively new field of research with high functional potential. The multicomponent design space is immense and practically unexplored. An important obstacle for academic research of such sputtered films is the availability of single‐alloy targets and technical difficulties in using cosputtering of multiple metal targets or powder targets. This article focuses on the development of a simple powder metallurgy route, including cold uniaxial pressing of powder mixtures followed by pressureless sintering, for the preparation of targets made of two common base alloys forming simple solid solutions, i.e., FeNiCrCo and FeNiCrMn. In addition, targets of the former one containing 10 at% Al are also prepared. The sintered pellets are composed of randomly oriented crystallites with face‐centered cubic structures and an optimum chemical homogeneity. Oxide inclusions and residual porosity, inherent to consolidation and sintering of metal precursors, are observed and possible solutions to overcome these challenging problems are discussed. Nevertheless, encouraging results from preliminary deposition tests of FeNiCrCoAl0.4 using both direct current magnetron sputtering (DCMS) and high‐power impulse magnetron sputtering (HiPIMS) are presented.

Production of positron-emitting radionuclide yttrium-86 with a computer-aided design target for positron emission tomography

Yttrium-86 (86Y, t1/2 = 14.7 h, 33% β+) is a nonstandard medical nuclide with a longer half-life than other standard nuclides such as gallium-68 for radiolabelling for PET (positron emission computed tomography) imaging. 86Y is compatible with DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and can be used to evaluate DOTA-chelated radiopharmaceuticals with long clearance half-lives, particularly therapeutic radiopharmaceuticals in several days. 86Y can be produced through 86Sr(p, n)86Y reaction, in which 86Sr-enriched SrCO3 powder is bombarded with low-energy protons. To handle the SrCO3 powder, a powder target for 86Y production in 14.6 MeV proton cyclotron was designed while maximizing yield, reliability and efficiency. To that end, the target's primary design parameters were traversed, simulated and optimized using computer algorithms to obtain advantageous parameter combinations. In this way, 86Y was produced on the powder target with high yield and successfully isolated with high purity (>97%) by solid-phase extraction via DGA resin for high-quality PET imaging and drug screening.

Measurement and analysis of impact dynamics suitable for modelling pneumatic transport of metallic powder flow through a directed energy deposition nozzle

In blown powder directed energy deposition (DED) additive manufacturing powdered metal feedstock is pneumatically conveyed to the meltpool via a nozzle. DED nozzles have been the subject to a growing number of research efforts using computational fluid dynamics (CFD) with multiphase flows to study and optimize powder flow. However, many research papers published to date contain powder – nozzle impact dynamics behavior that is not realistic or not derived from experiments that resemble the powder conveyance process in the DED nozzle being studied. To provide a set of data representative of DED powder flow through a nozzle particle image velocimetry (PIV) experiments were conducted using 316L stainless steel metal powder and flat targets with varying surface roughness made of oxygen free copper, mild steel, P20 tool steel, 316L stainless steel, Inconel 718, and Ti-Al6-V4. Normal coefficients of restitution (COR) were calculated and compared to several analytical and empirical models in literature.

Separation of103Pd from a Rh target using an alloying pretreatment with bismuth

AbstractPalladium-103 is one of the most attractive radionuclides for internal radiotherapy. It is not only used as a brachytherapy seed but is also a feasible candidate for Auger electron therapy and gold-nanoparticle therapy. In this study, we propose a new method for the separation of103Pd from a rhodium target to obtain no-carrier-added103Pd. Rhodium powder target was irradiated under the following conditions: proton, 50 MeV, 1–3 μA, 1–4 h for the separation study; and H2+, 24 MeV, 5 μA, 1 h to produce103Pd. The irradiated target was pretreated using an alloying reaction between Rh and Bi on a hotplate at 500 °C. Rhodium in the chemical form of a Bi–Rh compound could then be dissolved with nitric acid and103Pd was extracted using dimethylglyoxime as an extractant. The target rhodium was recycled using sodium tetrahydroborate (NaBH4). We obtained103Pd with a yield of 87%. The activity of the product was 26 ± 2 MBq at the end of bombardment (EOB), and the radionuclidic purity of103Pd was greater than 99%. The decontamination factors of rhodium and bismuth in the103Pd product were estimated to be greater than 104and 105, respectively. The target rhodium was recycled with a yield of 91% with a trace of bismuth (9 μg/50 mg Rh). The total separation time for103Pd was within 3.5 h.

Fabrication of thin solid electrolytes containing a small volume of an Li3OCl-type antiperovskite phase by RF magnetron sputtering

RF magnetron sputter deposition was performed using an Li2O + LiCl powder target. The resulting solid electrolyte films were found to contain a small volume fraction of an Li3OCl-type antiperovskite phase.

Preparation of functional thin films with elemental gradient by sputtering with mixed powder targets

Functional thin films with a compositional gradient were deposited by a sputtering method with mixed powder targets. The composition ratio of nickel (Ni) and stainless steel (SUS304) was varied over the film thickness using several types of nickel oxide and stainless steel mixed powder targets. Our results indicate that mixed nickel-doped stainless-steel thin films were successfully prepared on both stainless-steel and Si substrates and the mixing ratio was controlled by the composition of the nickel oxide and stainless steel mixed powder.