Zirconium Target Research Articles

Corrosion behavior in simulated environments of ITZO films prepared by two targets co-sputtering

Indium tin zirconium oxide (ITZO) films were deposited by a co-sputtering technique with ITO and zirconium targets. The stability and corrosion behavior of films in simulated environments were studied on account of microstructure and optical–electrical properties. The results show that ITZO films possess a better crystalline structure and optical–electrical properties. Zirconium-doping changes the preferred orientation of ITO films, and ITZO films under the optimum parameters have sheet resistance of 10Ω/sq and transmittance of above 85%. According to the polarization measurements and the relative resistance change of the films in simulated environments such as acidic climate, oceanic climate and industrial climate, the doping films show better chemical and thermal stabilities than ITO films. Besides the influence of crystal structure, the better stability of zirconium oxide can improve the chemical and thermal stabilities. ITZO films have better electrical stability and chemical antcaustic properties, and the films could find more extensive applications.

COMPORTAMIENTO DE CORROSIÓN-EROSIÓN EN RECUBRIMIENTOS DE TiN/ZrN DEPOSITADOS SOBRE ACERO AISI 4140

Thin films of titanium nitride/zirconium nitride were deposited on AISI 4140 steel by a multi-target magnetron sputtering system with radio frequency. The process was developed under the substrate rotation system which allowed placing the substrate against the titanium and zirconium targets, generating the super-lattice with periods of 1, 50, 100, and 200 bilayers. The multilayers were evaluated against the corrosion-erosion synergy in a solution composed by 3% NaCl and silica. The electrochemical characterization was performed by electrochemical impedance spectroscopy. After the mechanic and electrochemical tests the surface was evaluated using scanning electron microscopy. By performance analysis it was observed that the material with higher synergic effect was the substrate. It is also shown that by increasing the bilayers in the system titanium nitride/zirconium nitride the corrosive phenomenon controls the material deterioration.

Manufacturing of Zirconia (ZrO2) Nanoparticlesin Sodium Dodecyl Sulfate Surfactant Solution Using Laser Ablation Technique

Pulsed Laser Ablation in Liquid (PLAL) has become an increasingly important technique for metals production and metal oxides nanoparticles (NPs) and others. This technique has its many advantages compared with other conventional techniques (physical and chemical). This work was devoted for production of Zirconia (ZrO2) nanoparticles via PLAL technique from a solid zirconium target immersed in a group of wet environments in order to study the effect of different surfactants on the optical properties and structure of ZrO2 nanoparticles. The solutions which used for this purpose are sodium dodecyl sulfate (SDS). The produces NPs were characterized by mean of many tests such as UV-visible (UV-Vis.), Transmission Electron Microscope (TEM) and Z-Potential. The UVVis spectra show a blue shift in the presence of SDS solution which indicates quantum confinement property of the NPs. The TEM test shows less than 10 nm average particle sizes with spherical and irregular shapes. It was found that use surfactant solution leads to significantly higher ablation efficiency accomplished with finer spherical nanoparticles sizes. Z-Potential test shows values in the range of (-41.3) mV and (+56.1) mV which indicate for NPs stability with extremely low agglomeration solution.

Process stabilization and a significant enhancement of the deposition rate in reactive high-power impulse magnetron sputtering of ZrO2 and Ta2O5 films

High-power impulse magnetron sputtering with a pulsed reactive gas (oxygen) flow control was used for high-rate reactive depositions of densified stoichiometric ZrO2 and Ta2O5 films onto floating substrates. The depositions were performed using a strongly unbalanced magnetron with a planar zirconium or tantalum target of 100mm diameter in argon–oxygen gas mixtures at the total pressure close to 2Pa. The repetition frequency was 500Hz at the average target power density from 5Wcm−2 to 103Wcm−2 during a deposition. The duty cycles ranged from 2.5% to 10%. The target-to-substrate distance was 100mm. For the same duty cycle of 10%, the deposition rates were up to 140nm/min for the ZrO2 films and up to 345nm/min for the Ta2O5 films. The ZrO2 films were crystalline with a dominant monoclinic phase. They exhibited a hardness of 16GPa, a refractive index of 2.19–2.22 and an extinction coefficient of 2×10−3–6×10−3 (both at the wavelength of 550nm). The Ta2O5 films were nanocrystalline. They exhibited a hardness of 7GPa, a refractive index of 2.09–2.15 and an extinction coefficient of less than 1×10−4.

Microstructure evolution of radio-frequency magnetron sputtered oxide thin films in the Cr–Zr–O system

Oxide thin films in the Cr–Zr–O system with various microstructures and properties were synthesized by reactive radio-frequency magnetron sputtering of a segmented chromium–zirconium target. Nanocrystalline Cr–Zr–O thin films with continuously changing compositions from chromium-rich to zirconium-rich were obtained in a single deposition process. The Cr–Zr–O thin films were characterized by electron probe microanalysis, X-ray diffraction and transmission electron microscopy. Up to a zirconium content of 12at.% films with a metal/oxygen concentration ratio of 2/3 were deposited. These films revealed a single-phase solid solution (Cr,Zr)2O3 corundum structure. An increasing zirconium (and decreasing chromium) concentration promoted the formation of ZrO2 structures accompanied by a change of the metal/oxygen concentration ratio towards 1/2. First, a cubic, then a tetragonal phase was formed, while at the highest zirconium content a monoclinic phase evolved in addition to the tetragonal phase. Microindentation analysis showed for the single-phase corundum films an increase in hardness of about 20% to 19GPa with an increase of the zirconium content from 8at.% to 12at.%. Films with a ZrO2 structure exhibited indentation hardness values superior to those reported for bulk cubic and monoclinic ZrO2.

Synthesis of Zirconia Nanoparticles in Distilled Water Solution by Laser Ablation Technique

Pulsed laser ablation in liquid (PLAL) has become an increasingly important technique for metals production and metal oxides nanoparticles (NPs) and others. This technique has its many advantages compared with other conventional techniques (physical and chemical). This work was devoted for production of zirconia (ZrO2) nanoparticles via PLAL technique from a solid zirconium target immersed in a wet environment in order to study the effect of this environment on the optical properties and structure of ZrO2 nanoparticles. The solutions which used for this purpose is distilled water (D.W). The produces NPs were characterized by mean of many tests such as UV-visible (UV-Vis.), transmission electron microscope (TEM) and Z-Potential. The UV-Vis. A spectrum has atwavelength is 271 nm. The TEM test shows less than 10 nm average particle sizes with spherical and irregular shapes. Z-Potential test shows value about +56.1 mV which indicate for NPs stability with extremely low agglomeration solution.

Effect of power variation on wettability and optical properties of co-sputtered titanium and zirconium oxynitride films

The present paper deals with deposition of titanium and zirconium oxynitride films prepared from co-sputtering titanium and zirconium targets by reactive RF magnetron sputtering. The effect of power variation on various properties of the deposited films is analysed. The film gets transformed from amorphous to well crystalline oxynitride films with gradual increase of target powers as observed from XRD graphs. The films exhibit hydrophilic and hydrophobic behaviours depending upon the presence of various phases. Surface energy decreases as the film properties change from hydrophilic to hydrophobic due to greater contact angle values. The optical properties were measured by UV–Vis–NIR spectrophotometer, transmission spectra and bandgap values show variation with respect to change in elemental composition as determined from EDS analysis.

Mass attenuation coefficients of fabricated Rhizophora spp. particleboard for the 15.77 – 25.27 keV range

The Rhizophora spp. wood what is hard and heavy is considered strong in strength and is suitable for structural purposes. Generally, Rhizophora spp. was used in radiation dosimetry research and it is being used in this project too. There are some disadvantages in using the raw (natural) material of Rhizophora spp. in radiation dosimetry research and there is a need to modify this natural wood to be easily used as a phantom in radiation dosimetry. The mass attenuation coefficients (/) of fabricated Rhizophora spp. particleboard were determined for photons in the energy range of 15.77–25.27 keV. This was carried out by studying the attenuation of X-ray fluorescent photons from zirconium, molybdenum, palladium, silver, indium and tin targets. The results were compared with theoretical values for average breast tissues in youngage, middle-age and old-age groups calculated using photon cross section database (XCOM), the well-known code for calculating attenuation coefficients and interaction cross-sections. The measured mass attenuation coefficients were found to be very close to the calculated XCOM values in breasts of old-age group.

Preparation of magnetron sputtered ZrO2 films on Si for gate dielectric application

Zirconium oxide (ZrO2) thin films were deposited on to p – Si and quartz substrates by sputtering of zirconium target at an oxygen partial pressure of 4x10−2 Pa and sputter pressure of 0.4 Pa by using DC reactive magnetron sputtering technique. The effect of annealing temperature on structural, optical, electrical and dielectric properties of the ZrO2 films was systematically studied. The as-deposited films were mixed phases of monoclinic and orthorhombic ZrO2. As the annealing temperature increased to 1073 K, the films were transformed in to single phase orthorhombic ZrO2. Fourier transform infrared studies conform the presence of interfacial layer between Si and ZrO2. The optical band gap and refractive index of the as-deposited films were 5.82 eV and 1.81. As the annealing temperature increased to 1073 K the optical band gap and refractive index increased to 5.92 eV and 2.10 respectively. The structural changes were influenced the capacitance-voltage and current-voltage characteristics of Al/ZrO2/p-Si capacitors. The dielectric constant was increased from 11.6 to 24.5 and the leakage current was decreased from 1.65×10−7 to 3.30×10−9 A/ cm2 for the as-deposited and annealed at 1073 K respectively.

90Nb – a potential PET nuclide: production and labeling of monoclonal antibodies

Abstract Fast progressing immuno-PET gives reasons to develop new potential medium-long and long-lived radioisotopes. One of the promising candidates is 90Nb. It has a half-life of 14.6 h, which allows visualizing and quantifying processes with medium and slow kinetics, such as tumor accumulation of antibodies and antibodies fragments or polymers and other nanoparticles. 90Nb exhibits a high positron branching of 53% and an optimal energy of β + emission of E mean=0.35 MeV only. Consequently, efficient radionuclide production routes and NbV labeling techniques are required. 90Nb was produced by the 90Zr(p,n) 90Nb nuclear reaction on natural zirconium targets. No-carrier-added (n.c.a.) 90Nb was separated from the zirconium target via a multi-step separation procedure including extraction steps and ion-exchange chromatography. Protein labeling was exemplified using the bifunctional chelator desferrioxamine attached to the monoclonal antibody rituximab. Desferrioxamine was coupled to rituximab via two different routes, by the use of N-succinyl-desferrioxamine (N-suc-Df) and by means of the bifunctional derivative p-isothiocyanatobenzyl-desferrioxamine B (Df-Bz-NCS), respectively. Following antibody modification, labeling with 90Nb was performed in HEPES buffer at pH 7 at room temperature. In vitro stability of the radiolabeled conjugates was tested in saline buffer at room temperature and in fetal calf serum (FCS) at 37 ºC. The selected production route led to a high yield of 145 ± 10 MBq/μA h of 90Nb with high radioisotopic purity of >97%. This yield may allow for large scale production of about 10 GBq 90Nb. The separation procedure resulted in 76–81% yield. The Zr/90Nb decontamination factor reaches 107. Subsequent radiolabeling of the two different conjugates with 90Nb gave high yields; after one hour incubation at room temperature, more than 90% of 90Nb-Df-mAb was formed in both cases. At room temperature in aqueous solution, both 90Nb-Df-mAb constructs were more than 99% stable over a period of 18 d. The developed production and separation strategy provided 90Nb with purity appropriate for radiolabeling applications. Labeling and stability studies proved the applicability of 90Nb as a potential positron emitter for immuno-PET.

Optical emission from metal targets bombarded by 5–20 keV argon ions

The spectral composition of optical emission from high-purity iron (99.99% Fe), zirconium (99.98% Zr), and tungsten (99.96% W) targets bombarded by 5–20 keV Ar+ ions has been studied. The ion-bombardment-induced emission spectra of all metals exhibit two broad bands in the visible and IR spectral range. The first band is assigned to the emission from thermal spikes representing nanosized regions heated to 5000–6000 K, which are formed at the target surface in the course of evolution of high-density atomic collision cascades. The presence of an IR emission band is explained by the integral heating of targets to 500–800 K in the course of ion irradiation. This interpretation is confirmed by agreement between the experimentally measured and calculated temperatures in the region of thermalized collision cascades and the relative intensities of emission bands.

Intrinsic Paramagnetic Defects in Zirconium and Hafnium Oxide Films

ABSTRACTThin films of zirconium oxide (ZrOx) and hafnium oxide (HfOx) were rf sputtered onto fused silica substrates in an oxygen rich argon environment. Pure zirconium and hafnium targets were used, and the oxygen partial pressure was varied to control the oxygen stoichiometry. Measurement of the EPR characteristics of the ZrOx films indicated two peaks corresponding to two orientations of the magnetic field. This anisotropic response suggested the films were polycrystalline with a preferred orientation. This was confirmed by XRD pole figures. The measured g-values for the ZrOx films were less than the free-spin g-value, indicating the defects corresponded to electron traps. It was further shown that the lower the oxygen partial pressure during deposition, the larger the EPR response, strongly suggesting the traps correspond to oxygen vacancies in ZrOx. Hafnium oxide thin films were also characterized by EPR. The EPR measurements indicated the presence of a single resonance peak, suggesting these films were polycrystalline without a preferred orientation or amorphous. XRD measurements confirmed that the HfOx films were amorphous. The g-value for these films was greater than that the free-spin value, indicating the presence of possibly self-trapped oxygen hole centers. These results will be discussed in the context of prior experimental and theoretical work on these systems.

Apatite Deposition on ZrO<sub>2</sub> Thin Films by DC Unbalanced Magnetron Sputtering

Zirconia thin films deposited on 316L stainless-steel substrate were prepared by DC unbalanced magnetron sputtering from a metallic zirconium target at low temperature with the target-to-substrate distance (dt-s) of 100 mm and sputtering power of 180 W. High purity gas of Ar as the working gas and O2 as the reactive gas were used. The depositions were performed for 120 min at a total pressure of 0.5 Pa. The effect of thermal treatment on the HA formation was investigated. The bioactivity was assessed by investigating the formation of hydroxyapatite (HA) on the surface soaked in simulated body fluids (SBF). Films structure, surface morphology and chemical composition of the ZrO2 films and HA formation were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and FT-IR spectroscopy. The XRD results demonstrate the ZrO2 films are monoclinic phase. The annealed films show the higher film crystalline due to the rearrangement of film structure. After being immersed the samples in SBF, the bone-like apatite was observed on all ZrO2 films, but a denser and more continuous HA layer were observed on annealed films due to the crystallinity of ZrO2 films.

Cross-section measurements and nuclear model calculation for proton induced nuclear reaction on zirconium

Proton induced nuclear reactions were measured with stacked-foil technique on natural zirconium targets up to 16.7MeV. Excitation functions were measured for the production of (90,92m,95m,95g,96)Nb and (88)Y. Cumulative cross-section, thick target yields and activation functions were deduced and compared with the available experimental data, as well as with the nuclear models codes; ALICE-IPPE, EMPIRE and TALYS. The integral yields for thick targets were deduced from the measured excitation function of the produced radionuclides.

SU‐E‐I‐171: On the Potential for the Production of 99Mo and 99mTc from Light‐ Ion Reactions Based Zirconium + Lithium

Purpose: To explore alternative methods based upon light‐ion beams to generate 99Mo and/or 99mTc, used in nuclear medicine imaging, due to a worldwide supply shortage of these materials from nuclear reactors. Method and Materials:Fusion‐evaporation statistical Monte Carlo code PACE4 was used to evaluate the excitation functions, i.e. cross‐sections vs. energies, of nuclear reactions that may have a potential for the production of 99Mo or 99mTc. The calculated results were compared with the experimental data to validate the code and to estimate the scale‐up or ‐down factors. Results: For reactions involving evaporating neutrons, the calculation has the right trend but overestimates cross sections by about 7 times. The maximum calculated cross sections for 96Zr(7Li, 4n)99mTc, 96Zr(6Li, 3n)99mTc, and 94Zr(7Li, 2n)99mTc are 1130 mb, 801 mb, and 146 mb, respectively. The actual cross sections may be lower, but even the scaled down values of 161 mb (1130/7) and 114 mb (801/7) are still quite high and could be used to generate significant amount of 99mTc . For those reactions with exiting charged particles besides neutrons, the code underestimates the cross sections by about 10 times. The maximum calculated cross sections for 96Zr(7Li, d2n)99Mo, 96Zr(6Li, dn)99Mo, and 94Zr(7Li, d)99Mo are 42.6 mb, 21.6 mb, and 8.51 mb. The actual cross sections could be higher. If scaled cross sections of 426 mb and 216 mb are realistic, it will be much easier to get 99Mo from 96Zr(7Li, d2n)99Mo and 96Zr(6Li, dn)99Mo, not to mention that the specific activity of 99Mo could be much higher under the optimized reaction conditions. Conclusions: Specific activity and cross sections of nuclear reactions based on zirconium target using a light‐ion beam of helium or lithium may be much higher than those based on molybdenum target. These reactions should be investigated experimentally.

Development and Analysis of Robust Anti-Wear Design of a-C:Zr Films by Taguchi Methods

Amorphous carbon (a:C-H) coatings with high hardness and low friction coefficient are widely applied in die and mold industries. Zirconium-containing a:C-H (a-C:Zr) coatings with double interlayered Zr/ZrC were deposited by unbalanced magnetron sputtering system. A L18 orthogonal array experiment was designed to investigate the effect of process parameter on the friction coefficient of deposited films. Control factors, such as methane flow rate, bias voltage, sputtering frequency, zirconium target current and work distance were schematized for experiments. The experimental results show that zirconium target current exhibits about 45% percent contribution in analysis of variance, and the friction coefficient of a-C:Zr coatings range from 0.13 to 0.31. From effect plots, the optimum parameters are bias voltage at -70V, zirconium target current at 0.6 A, pulse frequency at 90 kHz, methane flow rate at 6 sccm and work distance at 15 cm. The friction coefficient performs as 0.106 in verification experiments. Meanwhile, one-by-one factorial experiments were also carried out and discussed in this study.

Structure and properties of ZrN coatings deposited by high power impulse magnetron sputtering technology

Monolayer ZrN coatings were deposited exclusively by the novel high power impulse magnetron sputtering (HIPIMS) technology in an industrial scale physical vapour deposition (PVD) machine (HTC-1000-4 target system). Coatings were deposited on 1 μm polished M2 high speed steel, on 304L stainless steel (SS), and on Si (100) specimens. Prior to deposition, HIPIMS plasma sustained on a zirconium (Zr) target was utilized to pretreat the specimens. Coatings were deposited at 400 °C in a mixed N2 and Ar atmosphere using 2 magnetrons in HIPIMS mode and at three different substrate bias voltages (Ubias) keeping all other process parameters constant. The thicknesses of the coatings measured by the ball cratering technique were in the ranges of 1.84, 1.96, and 2.13 μm at bias voltages of −95, −75, and −65 V, respectively, where the difference in thickness can be attributed to the resputtering effect. X-ray diffraction experiments on SS specimens revealed a dominating 111 texture for all three coatings irrespective of the bias voltage. Cross-sectional transmission electron microscopy revealed extremely dense coating structures at all bias voltages, similar to the transition zone structure (zone T) reported by Thornton. The −95 bias voltage coatings appeared extremely smooth on the top and with no dome shaped structures often associated with low ion bombardment during deposition. HIPIMS pretreatment leads to high adhesion (LC) of the coatings to the substrate. A continuous ductile perforation of the coating was observed at progressive loads greater than 65 N; however, no spallation of the coating was observed up to loads of 100 N. High values of hardness (40.4 GPa), Young’s modulus (424 GPa), and compressive stress (10 GPa) were recorded for coatings deposited at −95 BV. The hardness and internal stress of the coating were found increasing with more negative bias voltages. All the coatings exhibited high dry sliding wear resistance (KC) in the range 6×10−15 m3 N−1 m−1. Cross-sectional transmission electron microscopy and atomic force microscopy analyses have been used to study the effect of ion bombardment obtained from HIPIMS on the structure of the coatings.

The influence of substrate-target orientation on the properties of ZrN films deposited by arc ion plating

The crystallograpic structure and properties of Zirconium nitride (ZrN) films deposited on 304 stainless steel were investigated. The substrates were placed either parallel with or perpendicular to the Zirconium target. The ZrN films were found to exhibit {311} orientations when substrate parrallel with target, however {220} orientation when substrates perpendicular to target. SEM results showed that the parallel ZrN films have round-shaped droplets, and perpendicular orientation ZrN films have oval-shaped droplets. The thickness of ZrN films in parallel mode is 1/2 of that in perpendicular mode. Nanoindentation results showed the hardness of ZrN films in perpendicular mode is lower than that of parallel mode. Potentiodynamic scanning results showed the corrosion resistance of films in perpendicular mode is better than that of films in parallel mode.

Preparation and Characterization of ZST Films for CMOS Applications

Zirconium tin titanate (Zr, Sn)TiO4 (ZST) thin films have been deposited at ambient temperature by dc magnetron sputtering from individual titanium, zirconium and tin metal targets on platinized silicon substrates. The present study demonstrates the possibility of growing zirconium tin titanium oxide films in 100% pure dc oxygen plasma. Films having thickness of the order of 450 nm have been grown starting from the metallic Zr, Ti and Sn targets in pure oxygen plasma. The grains as observed from atomic force microscope images are found to be a mixture of spherical and triangular geometry. The maximum value of dielectric constant and loss are found to be 53.7 and 0.0075 (at 5 MHz) for the films deposited at 40% Oxygen Mixing Percentage (OMP). The magnitude of current density and the breakdown field strength of the ZST films deposited at 40% OMP are found to be 9.72 × 10−7 Amp/cm2 and 62.5 KV/cm respectively. The effect of processing parameters on structural, microstructural, optical, dielectric and electrical properties of the (Zr,Sn)TiO4 films have been investigated.

Ion flux characteristics and efficiency of the deposition processes in high power impulse magnetron sputtering of zirconium

High power impulse magnetron sputtering of zirconium was investigated at the average target power density of up to 2.22 kW cm−2 in a pulse. The depositions were performed using a strongly unbalanced magnetron with a planar zirconium target of 100 mm diameter at the argon pressure of 1 Pa. The repetition frequency was 500 Hz at duty cycles ranging from 4% to 10%. Time-averaged mass spectroscopy was carried out at the substrate positions of 100 and 200 mm from the target. The increase in the average target power density from 0.97 kW cm−2 to 2.22 kW cm−2 in shortened voltage pulses (from 200 to 80 μs) at an average target power density of 100 W cm−2 in a period led to high fractions (21%–32%) of doubly charged zirconium ions in total ion fluxes onto the substrate located 100 mm from the target. However, the respective fractions of singly charged zirconium ions decreased from 23% to 3%. It was observed that ion energy distributions were extended to high energies (up to 100 eV relative to the ground potential) under these conditions. The increased target power densities during the shortened voltage pulses resulted in a reduced deposition rate of films from 590 to 440 nm/min and in a weakly decreasing ionized fraction (from 55% to 49%) of the sputtered zirconium atoms in the flux onto the substrate. The doubly charged zirconium ions became strongly predominant (up to 63%) in the total ion flux onto the substrate at the distance of 200 mm from the target. Model calculations were carried out to explain the complicated deposition processes.