Hydrogen Content Of Samples Research Articles

Peculiarities of Application of the Gas Extraction Method for Determination of Hydrogen Content in Samples of Irradiated Zirconium Materials

Results of multiyear research of zirconium materials from nuclear reactors show that the hydrogen content measured by a high-temperature extraction method does not always correlate with the number and size of zirconium hydrides measured by metallography. Additional examinations found that hydrogen is contained not only in the metal but also in the oxide film of samples under examination. This means that the level of hydrogenation of zirconium materials under irradiation should be estimated by the hydrogen content in metal only to allow for a correct comparison of the results of gas analysis and metallographic investigations. In this connection, the hydrogen content was measured separately in the metal and in the oxide film. A device to mechanically remove sediments and oxide film from samples was developed. However, when removing the oxide mechanically, a top layer of metal is also removed, as a rule, which leads to an uncontrolled increase in the measurement error because of a nonuniform distribution of hydrides in the metal. The assessment of the contribution of oxide hydrogen using a curve “total hydrogen content vs. oxide film thickness” showed no distinct dependence. Moreover, it was stated that the results of the total hydrogen content measurements by the high-temperature extraction method can be affected by the elementary composition of sediments and oxide films on the surfaces of spent items. The performed research resulted in the development of a technique to measure the hydrogen mass fraction by high-temperature extraction in an inert gas flow separately in the metal and oxide film without any preliminary mechanical removal of the oxide. This will allow examining the dependence between the hydrogen content in the oxide film and its thickness, as well as estimating a possible correlation between the hydrogen mass fraction in the metal and the quantitative characteristics of hydrides measured by a metallographic image.

Preliminary research on method of tree ring’s NE-OBT measurement using AMS

The non-exchangeable organically bound tritium (NE-OBT) concentration in the cellulose of tree rings can accurately reflects the tritiated water concentration in the local environment and often contains the only historical record of tritium exposure. However, there is few study about NE-OBT measurement using AMS around the world, especially in China. Furthermore, in order to measure tritium in tree rings exactly, it is necessary to solve several key problems during sample preparation. In this study, the optimized sample preparations procedure are investigated. The purity of cellulose extracted by improved sodium hypochlorite pretreatment method is about 83.9%, considerably higher than the 64.8% conventional methods. Pure TiH2 samples reaching requirements of AMS measurement have been made. The isotope fractionation is stabilized during sample preparation. Preliminary results of sample analysis using a compact AMS with 200 kV accelerator are presented. Currently, the minimum T/H ratio that can be accurately measured is only about 10−12, limited by hydrogen contents in samples and instrument conditions. Further works will be done in order to achieve lower detection limits and better accuracy.

Influence of Hydrogen Adsorption on Electrodeposition of Platinum from Chloro Complex Solution

Platinum (Pt) is widely used as insoluble and catalytic electrodes for electrolysis, automotive catalytic converters, and fuel cells. We have been investigating hydrogen incorporation in electrodeposited metal films and its influence on crystal structure of metals (1-3). It was reported that large amount of hydrogen (content in atomic ratio: x = H/Pt = 0.1) is incorporated in the Pt films electrodeposited from a solution including dinitrosulfatoplatinate(II) (H2Pt(NO2)2SO4, DNS) as a metal source. In this study, an electrochemical quartz crystal microbalance (EQCM) method (4) is used to examine influence of hydrogen adsorption on the electrodeposition and hydrogen incorporation into deposited films of Pt from a chloro complex solution. The current-potential and mass increase (Pt deposition rate)-potential curves in 0.024 mol dm-3 K2PtCl4solution adjusted at pH of 0.8 with HCl were measured using an EQCM system (Hokuto Denko, HQ-101D and HZ-5000). A quartz electrode coated with Au, an Ag/AgCl electrode, and a Pt wire were used as the working, reference, and counter electrodes, respectively. The hydrogen content of samples was measured by thermal desorption spectroscopy (TDS). Figure 1 shows the current density and mass increase rate versus electrode potential curves for the chloro complex solution. In the first forward potential sweep toward negative potentials of Fig. 1(a), the cathode current and deposition rate of Pt started increasing at +0.3 V vs. Ag/AgCl. Peaks for cathode current and deposition rate appeared at -0.19 V. The current efficiency was 74% at this peak. Then, as the potential was swept to lower potentials, the deposition rate and current efficiency decreased. This decrease in the current efficiency of Pt deposition is caused by hydrogen adsorption. In the return potential sweep (Fig.1 (b)), the cathode current and Pt deposition steeply increased by hydrogen desorption from the Pt surface, and the current efficiency was 113% at the potential of -0.25 V. The hydrogen content of Pt-electrodeposited Au foil (Pt: 1 μm and Au: 20 μm in thickness) increased as the deposition potential of Pt decreased from 0 to -0.3 V, and was much lower than that deposited from the DNS solution. Acknowledgements The present work was partly supported by JSPS KAKENHI (26289276). References N. Fukumuro, M. Yokota, S. Yae, H. Matsuda, Y. Fukai, J. Alloys Compd., 580, S55 (2013). N. Fukumuro, S. Kojima, M. Fujino, Y. Mizuta, T. Maruo, S. Yae, Y. Fukai, J. Alloys Compd., 645, S404 (2015). N. Hisanaga, N. Fukumuro, S. Yae, H. Matsuda, ECS Trans., 50, 77 (2013). T. Hagihara, K. Yaori, K. Iwakura, N, Fukumuro, S. Yae, Electrochim. Acta, 176, 65 (2015). Figure 1

Impact of microwave post-deposition annealing on the crystallization of amorphous hydrogenated perovskites. The case of the three-dimensional tungsten and of the two-dimensional molybdenum oxide films

Hydrogenated sub-stoichiometric oxides exhibiting perovskite structure such as those of tungsten and of molybdenum (H:MOx, where M=W or Mo and x<3) were treated by microwave (MW) post-deposition annealing in air. The purpose of this treatment was to vibrate and therefore heat, the OH bonds present in them only, without heating the rest of the lattice and the substrate. It was shown that, contrary to thermal heating, MW annealing did not affect significantly the oxygen and hydrogen contents in samples, but it caused an atomic re-arrangement; more significant for H:MoOx than for H:WOx films, attributed to the layered, two-dimensional structure of the former contrary to the three-dimensional one of the latter. It was concluded that MW annealing at appropriately chosen frequencies may potentially be used to improve atomic ordering in other materials without causing alterations of their chemical composition and avoiding the heating of the substrate.

Multichannel diffusion vs TDS model on example of energy spectra of bound hydrogen in 34CrNiMo6 steel after a typical heat treatment

The paper is concerned with determination of the energy spectra of hydrogen in steels by the Vacuum Hot Extraction method (VHE). The investigation is performed on example of 34CrNiMo6 steel and the benchmark study of Vacuum Hot Extraction method and Thermal Desorption Spectroscopy (TDS) is provided. The spectrum of the hydrogen binding energy and the hydrogen concentration in samples are identified. Two additional energy levels are found out which are possibly related to strong covalent bonds. An advantage of VHE in comparison with TDS is that VHE approach does not require pre-saturation of samples by hydrogen. It keeps the original structure of the samples and ensures that all types of traps are not destroyed in tests. Additionally, the present approach opens new opportunity of accurate analysis on the base of the model of hydrogen multichannel diffusion in steels.

The influence of nickel layer thickness on microhardness and hydrogen sorption rate of commercially pure titanium alloy

The influence of nickel coating thickness on microhardness and hydrogen sorption rate by commercially pure titanium alloy was established in this work. Coating deposition was carried out by magnetron sputtering method with prior ion cleaning of surface. It was shown that increase of sputtering time from 10 to 50 minutes leads to increase coating thickness from 56 to 3.78 μm. It was established that increase of nickel coating thickness leads to increase of microhardness at loads less than 0.5 kg. Microhardness values for all samples are not significantly different at loads 1 kg. Hydrogen content in titanium alloy with nickel layer deposited at 10 and 20 minutes exceeds concentration in initial samples on one order of magnitude. Further increasing of deposition time of nickel coating leads to decreasing of hydrogen concentration in samples due to coating delamination in process of hydrogenation.

Saturation of hydrogen retention in gallium samples exposed to tokamak ISTTOK plasmas

Abstract The main objective of this work is to report on the measurements of in-depth profiles for the hydrogen retained in liquid gallium samples exposed to ISTTOK tokamak plasmas. Several samples were exposed to a large number of ISTTOK discharges varying the total exposure time (1, 3 and 10 s) to study saturation effects in retention. The sample hydrogen content was evaluated by means of ion beam analysis (ERDA and RBS). The analysis has shown evidences of saturation as the increase in hydrogen content from 3 to 10 s exposures is five times lower than for the 1 to 3 s samples. On the other hand XPS analysis show different behavior for surface and in-depth retention since a large fraction of the measured hydrogen is retained in the form of hydrocarbons and hydroxides on the sample surface region.

Hydrogen Charging Effects in Pd/Ti/TiO2/Ti Thin Films Deposited on Si(111) Studied by Ion Beam Analysis Methods

Titanium and titanium dioxide thin films were deposited onto Si(111) substrates by magnetron sputtering from a metallic Ti target in a reactive Ar+O2atmosphere, the composition of which was controlled by precision gas controllers. For some samples, 1/3 of the surface was covered with palladium using molecular beam epitaxy. Chemical composition, density, and layer thickness of the layers were determined by Auger electron spectroscopy (AES) and Rutherford backscattering spectrometry (RBS). The surface morphology was studied using high-resolution scanning electron microscopy (HRSEM). After deposition, smooth, homogenous sample surfaces were observed. Hydrogen charging for 5 hours under pressure of 1 bar and at temperature of 300°C results in granulation of the surface. Hydrogen depth profile was determined using secondary ion mass spectrometry (SIMS) and nuclear Reaction Analysis (N-15 method), using a15N beam at and above the resonance energy of 6.417 MeV. NRA measurements proved a higher hydrogen concentration in samples with partially covered top layers, than in samples without palladium. The highest value of H concentration after charging was about 50% (in the palladium-covered part) and about 40% in titanium that was not covered by Pd. These values are in good agreement with the results of SIMS measurements.

A comparison between cold and thermal neutron prompt gamma activation analysis in the determination of carbon, nitrogen, and phosphorus in cattail

Methods for the determination of total carbon (TC), total nitrogen (TN), and total phosphorus (TP) in cattail (Typha domingensis) using cold and thermal neutron prompt gamma activation analysis (CNPGAA and TNPGAA) have been developed in the CNPGAA and TNPGAA facilities at the National Institute of Standards and Technology (NIST), and evaluated through the analysis of Standard Reference Materials (SRMs) in previous studies. There are major issues that impact the sensitivities of C, N and P using CNPGAA and TNPGAA including the effects of hydrogen content in samples, sample thickness and Compton scattering. However, interference from chlorine (Cl) in cattails has a major impact on the detection of P. This paper compares the effects of hydrogen content, sample thickness and Compton scattering on the sensitivities of C, N, and P between CNPGAA and TNPGAA and provides a resolution to the Cl interference on P in cattail.

Sp 3/sp 2 character of the carbon and hydrogen configuration in micro- and nanocrystalline diamond

Hot filament and microwave plasma CVD micro- nanocrystalline diamond films are analysed by visible and ultra-violet excitation source Raman spectroscopy. The sample grain size varies from 20 nm to 2 μm. The hydrogen concentration in samples is measured by SIMS and compared to the grain size, and to the ratio of sp 2 carbon bonds determined by Raman spectroscopy from the 1332 cm − 1 diamond peak and the sp 2 1550 cm − 1 G band. Hydrogen concentration appears to be proportional to the sp 2 bonds ratio. The 3000 cm − 1 CH x stretching mode band intensity observed on the Raman spectra is decreasing with the G band intensity. Thermal annealing modifies the sp 2 phase structure and concentration, as hydrogen outdiffuses.

Novel Sieverts’ type volumetric measurements of hydrogen storage properties for very small sample quantities

Novel volumetric analysis instrument for studying hydrogen storage property of very small quantities (∼mg) of samples was developed and tested. Small pressure change arising from hydrogen uptake or release are precisely measured and equated to the change in the sample's hydrogen content using the gas law equation. Very small volume pressure reservoir enables these precise measurements, and all internal volumes are calibrated with high-purity helium gas. Capacity, equilibrium isotherm, and kinetic measurements can be performed in the pressure range of vacuum to 4 MPa and the temperature range from cryogenic-673 K. Test measurements were made on small carbon nanotube samples and measurement of less than ∼3 μg of hydrogen uptake was demonstrated, which corresponds to an accuracy of better than 0.15 wt% for a 2 mg sample.

Experimental detection of the hydrogen content in rock material by a pulsed neutron method

A pulsed neutron method to measure the water or hydrogen content in a rock material has been elaborated and tested on the experimental set-up at the fast neutron generator in the IFJ PAN (Kraków, Poland). A dedicated pulsed thermal neutron source has been designed, built and added to this set-up. The test experiments have been done using dry crumbled granite as the rock matrix. The hydrogen content in samples has varied through an addition of a defined amount of polyethylene. The time decay constant of the pulsed thermal neutron flux has been measured as a function of polyethylene content in the granite+polyethylene samples. The experimental results have been supplemented with Monte Carlo simulations of the experiments. Analytical estimations of the time decay constant in the examined geometry have also been done. Difficulties of the proposed experimental method at low values of the hydrogen content are discussed. The presented pulsed method to determine the hydrogen content, which is less than 10%, needs rock samples of volume about 3dm3. For a higher hydrogen content the volume of the sample can be lower – about 0.7dm3.

Effect of Absorbed Hydrogen on the Stress Corrosion Cracking (SCC) Susceptibility of Unirradiated Zircaloy Cladding

Effect of absorbed hydrogen on the stress corrosion cracking (SCC) susceptibility of unirradiated Zircaloy cladding was examined. The data obtained from literatures showed that the normalized ratios of SCC threshold stress (σth ) to 0.2% yield stress (σ0.2.) claddings, from which the influence of σ0.2 had been eliminated, increased with increasing hydrogen contents below 50ppm in unirradiated Zircaloy-2 and -4. For Zircaloy-4, the break point was observed in the relationship between normalized ratios of σth to σ0.2 and hydrogen content in sample at hydrogen content of approximately 50ppm. Thermodynamic calculations were carried out for the reaction between iodine gas and zirconium containing hydrogen. The results suggested that the reactions hardly occurred at increased hydrogen content and zirconium reacted with iodine gas only below 100 ppm of hydrogen. Since these tendencies correspond to those of the normalized ratios of σ th to σ0.2 on the hydrogen content, it is considered that hydrogen affects the reactions between iodine gas and zirconium and reduces the SCC susceptibility of Zircaloy cladding.

Phase transformations in titanium hydrides

In this study the experimental data on thin titanium foil interaction with hydrogen HFD are presented. This investigation concentrates on the solid state phase transformations in titanium substrate under isothermal regimes under excess hydrogen concentration in sample. Isotherms of the titanium-hydrogen interaction are interpreted by the XRD method and a titanium-hydrogen binary constitution diagram. At a temperature of 873 K in the concentration range of 44–50 at.%H the metastable γ-phase with a f.c.t. lattice structure ( c a > 1 ) with TiH chemical formula was identified.

Lengthening kinetics of $$(01\bar 10)$$ γ-TiH precipitates in α-Ti in the temperature range of 25 °c to 80 °c

Formation of y hydrides in α titanium involves a hcp → fct lattice transformation with hydrogen as an interstitial diffusing species. Since the crystallography of this reaction resembles that of a martensitic transformation and the hydrides form at temperatures where both titanium and hydrogen atoms may have negligible mobility, many investigators have concluded that γ hydrides form by a martensitic mechanism. In this study, the lengthening kinetics of \((01\bar 10)\) γ hydrides were determined using conventional transmission electron microscopy (TEM). The length of the hydrides was measured as a function of time, temperature, and hydrogen concentration in samples isothermally aged in the range of 25 °C to 80 °C. These measurements were compared with the Zener-Hillert model of volume-diffusion-controlled precipitate growth. The experimental results indicate that y hydride growth is diffusionally controlled at 25 °C and possibly interfacially controlled at aging temperatures of 50 °C and higher. These and other aspects of the transformation are discussed.

Hydrogen concentration profiles in quartz determined by a nuclear reaction technique

The nuclear reaction 19F(1H, αγ) 16O has been used to determine the hydrogen concentration in natural and synthetic quartz samples. The depth-profile of the hydrogen concentration in these samples has been determined in detail for the smoky and Xo quartzes. These profiles exhibit a region of high hydrogen concentration in the near surface region (down to a depth of ∼2000A), with a lower concentration in the bulk of the sample. The results provide a plausible explanation for the substantial disagreement between previous hydrogen analysis in these quartzes by other techniques. Evidence for hydrogen mobility in crystalline quartz under ion beam bombardment is presented and discussed.