Zr Foil Research Articles

Formation and Mechanistic Study of Self-Ordering ZrO<sub>2</sub> Nanotubes by Anodic Oxidation

Among all of the one dimensional nanostructures other than titania (TiO2) and carbon, zirconia (ZrO2) have started to gain interest due to its potential in catalytic and energy applications. ZrO2 nanotubes arrays have been prepared using electrochemical anodizing method of Zr foil in fluorine containing glycerol electrolyte. The morphology and structure of the ZrO2 nanotubes are strongly controlled by the applied electrochemical condition especially voltage. Nanotubes with diameter of 30 to 60 nm has been produced by controlling the anodization voltage from 10 to 40 V. The ZrO2 nanotubes formed in this method is partially crystalline even without the heat treatment. The wall thickness is ~10 nm. The self-aligned nanotubes produced by this method could be used for phocatalytic application. The degradation of methylene orange under UV light was successful when ZrO2 nanotubes made in 30 V is used.

Conventional and Propagation‐based Phase Contrast Imaging of Nanostructures Using Femtosecond Laser Driven Cluster Plasma Source and LiF Crystal Soft X‐ray Detectors

AbstractBright source of soft X‐ray emission was developed. Soft X‐ray radiation was produced by femtosecond laser pulses irradiation of submicron size CO2 clusters. These clusters were produced in custom designed supersonic nozzle from the mixture of the 10% CO2 +90 % He expanding gases. Lithium fluorine based soft X‐ray detectors was used for registration of absorption images of ultrathin (nanoscale) foils and biological structures illuminated by the developed source. It was demonstrated that even ifthe foil is essentially transparent for the soft X‐ray radiation (like 100 nm thick Zr foil), the image contrast could be significantly increased due to the influence of propagation‐based phase‐contrast effect when detector is placed at the proper distance behind the sample (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Determination of trace elements in human gallstone and bile by k0-INAA

The trace elements composition of gallbladder stones samples of the types cholesterol, pigment and mixed stones in addition to bile have been investigated by k0-instrumental neutron activation analysis (k0-INAA). The samples were obtained from several individuals of adult subjects of the Libyan population who undergone open surgery of gallbladder (cholecystectomy) at Al-khadra University Hospital in Tripoli. The samples were lyophilized, irradiated together with Au wire and Zr foil, which serve as flux ratio monitor and a parameter at TNRC. Concentrations of 24 elements in gallstone and 23 elements in bile were determined. The levels of the trace elements in the various samples investigated are measured and discussed. The reliability of the analysis was checked with several biological standard reference materials.

Study of the zirconium oxidation under heavy ion irradiation

The objective of the present paper is to put in evidence the influence of damages due to the collision cascades which take place at the end of the heavy ion micrometer range, on the zirconium surface oxidation.A comparison between two zirconium oxidation experiments under heavy ion irradiation performed in the same temperature and pressure conditions is presented. In the first experiment, a 6μm thick zirconium foil is irradiated with a 50MeV 129Xe beam which stops in the Zr foil. In the second one, a 2μm thick zirconium foil is crossed by the whole fission fragment distribution emitted in the 235U fission. In order to explain the unexpected increase of the oxidation rate observed in the first case, MeV argon irradiation experiments have been performed at IPNL. Results show that collision cascades created in the Zr foil, far from the surface, increase significantly the Zr oxidation.

Absolute calibration of extreme ultraviolet optical components with an x-ray-induced fluorescence source

A calibration system for extreme ultraviolet (EUV) optical components has been developed. In the system, x rays from a conventional tube induce fluorescence in source materials, which is detected with a gas flow counter or a charge-coupled device detector. The transmittance of an EUV filter (Zr foil) and the diffraction efficiency of a grazing incidence grating were measured and compared with measurements by other sources and calculations. The measured transmission of a filter for 13.5nm light was 14.4%±0.6%, which agrees well with 14.55% measured with synchrotron orbital radiation. As for the gratings, the first-order diffraction shows good agreement with the model calculation, while the second order one has a remarkable discrepancy between the measurement and the calculation.

A flexible laboratory-scale approach to alloying and tailoring of thin films by single-magnetron co-sputtering

Alloying thin solid films can be difficult, especially when more than two substances are involved and a low deposition temperature is required. If additional demands like flexibility, stability and straightforward process control are stated, the number of deposition processes at hand is rather limited. Therefore, a co-sputtering technique involving the partial coverage of a target surface with metal foil has been studied in this work. Adopted from an earlier work, it was expanded to magnetron sputtering in order to better suit general, small-scale alloying of thin films and coatings. To evaluate the process, carbon coatings were alloyed by co-sputtering a carbon target with Al, Ta, W or Zr foil. The influence of metal type and degree of target coverage on film composition and properties was investigated. It is concluded that this co-sputtering approach can be used to alloy thin films and coatings in a very simple and straightforward manner, with excellent possibilities of controlling the amount of alloying elements. Coating deposition proved successful, yielding films with a wide compositional variety. The process temperature was 70 °C and stability during operation excellent. Depending on type and amount of metal added, the grown coatings ranged from amorphous to highly crystalline. Their mechanical properties were also shown to vary greatly with chemical composition.

Magneto-optical trap and mass-separator system for the ultra-sensitive detection of 135 Cs and 137 Cs

We report the first magneto-optical trapping of radioactive 135Cs and 137Cs and a promising means for detecting these isotopes at ultra-sensitive levels by coupling a magneto-optical trap (MOT) to a mass separator. A sample containing both isotopes was placed in the source of a mass separator, ionized, mass-separated, and implanted in a Zr foil within the trapping cell. After implantation, atoms were released from the foil by inductive heating and then captured in a MOT that used large-diameter beams and a dry-film-coated cell to achieve high trapping efficiency. Trapped-atom numbers in the case of either isotope ranged from 104 to 107, as determined from the MOT fluorescence signal. Over this trapped-atom range, the MOT fluorescence signal was found to increase linearly with the number of atoms implanted in the foil and without isotopic bias to within 4%. In principle, this method can then provide a measurement of the 137Cs/135Cs ratio accurate to within 4% through the direct ratio of MOT fluorescence signals. The fluorescence signal from stable 133Cs, when implanted and released from the foil, was suppressed relative to MOT signals by more than seven orders of magnitude when the system was tuned to trap 135Cs or 137Cs. When combined with the isotopic selectivity of ≥105 for the mass separator, the overall suppression of 133Cs is expected to exceed 1012. At present our system delivers atoms from sample to MOT with an efficiency of 0.5%, has a trapped-atom detection limit of 4000 atoms, and achieves a sample-detection sensitivity of one million atoms.

Thermal Diffusivity Measurement of High-Conductivity Materials by means of Dynamic Grating Radiometry. Measurement Theory for Thin Film and Development of an Experimental Apparatus.

Accurate and simple measurement method for the thermal diffusivity of high-conductivity thin film is required for the design of very densely packed integrated circuits such as ULSI. In order to measure the thermal diffusivity of high-conductivity thin film such as graphite and diamond, a new apparatus based on a dynamic grating radiometry (DGR) has been developed. In DGR method, a sample surface is heated by interference of two pulsed laser beams, and the decay of temperature at a spot on the thermal grating is monitored by an infrared detector. In the ideal case where the grating period is much smaller than the light absorption length, the thermal diffusivity parallel to the surface can be determined from the decay constant and the grating period. To consider the two dimensional problem, the anisotropy of the thin film is detected by DGR. In this paper, the theory which can calculate the thermal diffusivity perpendicular to the plane is presented. The validity of DGR is discussed through the preliminary measurement for Zr foil and Graphite Sheet.

Thermal Diffusivity Measurement of High-Conductivity Materials by Dynamic Grating Radiometry

A new apparatus based on dynamic grating radiometry (DGR) to measure the thermal diffusivity of high-conductivity materials such as graphite and diamond has been developed. In the DGR method, a sample surface is heated by interference of two pulsed laser beams, and the decay of temperature at a spot on the thermal grating is monitored by an infrared detector. In the ideal case where the grating period is much smaller than the light absorption length, the thermal diffusivity parallel to the surface can be determined from the decay constant and the grating period. This paper describes a procedure to extract the thermal diffusivity parallel to the plane while eliminating the effect of anisotropy and gives results for a preliminary measurement using Zr foil. A quadratic dependence of the time constant on fringe space has been observed in the fringe space change. Data are also presented for a 0.1-mm-thick graphite sheet. The results indicate the capability of DGR to measure anisotropic high-conductivity materials.

Giant magnetoresistance effect in CoZr/Cu/Co spin-valve films (abstract)

A high sensitivity of giant magnetoresistance (GMR) has been observed recently from soft magnetic layers such as NiFe, NiFeCo, and FeCoB.12 Amorphous CoZr alloys present ultrasoft properties compared to NiFe.3 GMR has been investigated for amorphous CoZr/Cu/Co thin films grown by rf diode sputtering using a target consisting of a Co disk partially covered with a Zr foil. The influence of the argon pressure on Cu layer deposition, Cu thickness, and Zr content on magnetic and transport properties was analyzed. The highest value of transverse GMR obtained along the easy axis is 3.6% and the MR curve was saturated in a magnetic field of 100 Oe at room temperature. GMR shows scaling behavior with the sample composition. Very high sensitivity, around 1–2%/Oe was observed in a CoZr (3 nm)/Cu (3 nm)/Co (2 nm) sandwich. This study shows a large dependence of GMR on Cu thickness and the maximum of magnetoresistance strongly depending on the Ar pressure which modifies the interface roughness. The Zr content also influences the magnetotransport properties (ΔR/R and ΔR/RΔH). The difference in coercivity between soft magnetic CoZr and hard magnetic Co layers induces antiferromagnetic alignment. Therefore a high MR ratio and field sensitivity are achieved by improving the magnetic properties of the CoZr layer.

Chemical reactions of Zircaloy-4 and zirconium with (i) dicaesium telluride, Cs 2Te, (ii) caesium tellurite, Cs 2TeO 3, and (iii) tellurium, under different oxygen potentials

Although Zircaloy-4 and Zr foil are inert to solid Cs 2Te at 948 K, reaction occurred when O 2 was admitted from buffers in sealed systems over 168 h. The products consisted of a zirconium telluride (or caesium zirconium telluride) sandwiched between the foil and an outer layer of ZrO 2, thus hindering the release of Te. The depth of corrosion of the foil increased with an increase in oxygen potential. Similar experiments with caesium tellurite, Cs 2TeO 3(s), with and without buffers, caused more extensive corrosion although Zircaloy-4 was more resistant than Zr; the tellurite was reduced to Cs 2Te and Zr was oxidised to ZrO 2. Zircaloy-4 and Zr reacted with liquid Te to form a surface layer of ZrTe plus unidentified phases that seemed to be neither Zr 3Te nor Zr 5Te 4, but Zircaloy-4 was more resistant again than Zr. When oxygen was introduced from buffers, the ZrTe was then converted to ZrO 2. There was some evidence that tellurium in the form of ZrTe was sandwiched again between ZrO 2 and the substrate foil. Increasing the oxygen potential from −914 to −307 kJ mol −1 O 2 increased the depth of corrosion and the extent of ZrO 2 formation.

Reaction diffusion in the vanadium-zirconium system

Reaction diffusion in the vanadium-zirconium system has been studied in the temperture range 1273 to 1473 K by use of two types of semi-infinite couples, (pure V)-(pure Zr) and (pure V)-(Zr-13.5 at% V alloy) and a sandwich type couple, (pure V)-(pure Zr foil of 50 to ~ 200μm)-(pure V). In all three types of couples diffused above 1373 K parabolic growth of the V2Zr phase layer has been observed after respective incubation times. At 1473 K, the incubation time in the (pure V)-(pure Zr) couple is 24 h, however, it is 1 h in the (pure V)-(pure Zr foil of 50μm)-(pure V) couple and nearly zero in the (pure V)-(Zr-13.5 at% V alloy) couple. This suggests that for nucleation of the V2Zr phase during the reaction diffusion, the concentration at the interface of the phase boundary between theβ-phase (Zr-rich solid solution) and theγ-phase (V-rich solid solution) is required to reach the nearly equilibrium one. It has been found that at the lower diffusion temperature the uphill diffusion of vanadium from theβ-phase contributes in part to growth of the V2Zr layer. In addition to the V2Zr phase, another phase, VZr, unexpected from the equilibrium phase diagram of the V-Zr system has been formed in the (pure V)-(pure Zr) couple diffused at 1473 K for more than 230 h.

Electron damage in zirconium: II. Nucleation and growth of c-component loops

Interstitial loops of b = 1 3 〈11 2 ̄ 3〉 have been observed to nucleate and grow during HVEM electron irradiation of Zr at temperatures ~ 650 K. Observations suggest that nucleation and early growth of these loops takes place on a combination of {101̄1} and {101̄0} planes. Subsequent glide of the glissile 1 3 〈11 2 ̄ 3〉 dislocations produces irregular loops which lie on irrational planes and are frequently chair-shaped. Of the six possible {101̄1} planes there are only two for which nucleation of these loops is observed in foils having normals close to 〈12̄10〉. These observations and observations of perfect 〈 a〉 type vacancy and interstitial loops have been interpreted in terms of the stress imposed in the Zr foil by the oxide formed during in situ irradiation at high temperature. The observations are discussed in terms of radiaton-induced growth.

Some Techniques for Sensitive Magnetic Measurements Using Superconducting Circuits and Magnetic Shields

A new superconducting circuit has been used in a sensitive magnetic susceptibility apparatus to detect changes in magnetic susceptibility as small as 10−10 cgs/g in a 104 Oe field, and in a low field magnetometer with which magnetic fields as low as 5×10−7 Oe have been measured. A low field superconducting shield for testing sensitive magnetometers has been developed and used to provide stable magnetic fields of less than 10−6 Oe, maintained stably for as long as six days. The measured attenuation of externally applied axial field changes is shown to be a factor of about 31 per shield radius. The stability of the persistent field of a Nb-25% Zr superconducting solenoid, observed over an 8 h period, indicated an average drift in the persistent solenoid field of less than one part in 1010/sec. Also, the attenuation of various high field magnetic shields of Nb-25% Zr foil was measured.

ON THE ROLLED TEXTURE AND RECRYSTALLIZATION OF Zr, Th AND La

Some experiments i. e. the preparation of ductile Th, work-hardening by rolling and texture of rolled Zr, Th and La plate, recrystallization of Zr foil have been examined. The results obtained are as follows;(1) The block prepared from powder Th by powder-metallurgy can be rolled to thin foil, though cracks break out.(2) The hardness of Th and La increase monotonously with the degree of reduction, but as for Zr it does not increase above 50% reduction.(3) The rolled Th plates have fibre structure of which axis is_??_111_??_parallel to the direction of rolling and_??_1120_??_with respect to Zr and La.(4) Rolled Zr plate begin recrystallization at 500°C when annealed 30min.