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Sample records for solutions h2so4 hf

  1. Recovery of Vanadium from H2SO4-HF Acidic Leaching Solution of Black Shale by Solvent Extraction and Precipitation

    Directory of Open Access Journals (Sweden)

    Xingbin Li

    2016-03-01

    Full Text Available The recovery of vanadium from sulfuric and hydrofluoric mixed acid solutions generated by the direct leaching of black shale was investigated using solvent extraction and precipitation methods. The process consisted of reduction, solvent extraction, and stripping, followed by precipitation and calcination to yield vanadium pentoxide. The influence of various operating parameters on the extraction and recovery of vanadium was studied. Vanadium (IV was selectively extracted using a mixture of 10% (v/v di(2-ethylhexylphosphoric acid and 5% (v/v tri-n-butylphosphate in sulfonated kerosene. Using six extraction and five stripping stages, the extraction efficiency for vanadium was 96.7% and the stripping efficiency was 99.7%. V2O5 with a purity of 99.52% was obtained by oxidation of the loaded strip solution and precipitation of ammonium polyvanadate at pH 1.8 to 2.2, followed by calcination of the dried precipitate at 550 °C for 2 h. It was concluded that the combination of solvent extraction and precipitation is an efficient method for the recovery of vanadium from a multi-element leach solution generated from black shale.

  2. Corrosion inhibition of carbon steel XC70 in H 2 SO 4 solution by ...

    African Journals Online (AJOL)

    In this work, we studied the efficiency of corrosion inhibition of carbon steel XC70 in H2SO4 0.5 M aqueous solution using ferrocenyl derivatives synthesized in our laboratory, this compound is: 3-(ferrocenylmethylamine)benzonitrile. The inhibitory potential of this compound was determined by electrochemical techniques ...

  3. Corrosion inhibition of nickel in H2SO4 solution by alanine

    International Nuclear Information System (INIS)

    Hamed, E.; Abd El-REhim, S.S.; El-Shahat, M.F.; Shaltot, A.M.

    2012-01-01

    Highlights: ► Corrosion of Ni in 1 M H 2 SO 4 in the absence and the presence of alanine. ► Alanine acts as a moderate mixed type inhibitor. ► Physical adsorption of alanine and formation of protective film are on Ni surface. ► Addition of KI improves the inhibition efficiency (synergistic effect). ► EFM technique is in reasonably good agreement with the different techniques used. - Abstract: The effect of alanine, as a safe inhibitor, was studied by measuring the corrosion of Ni in aerated and stagnant 1 M H 2 SO 4 solution (pH ∼0.2). Measurements were performed under various conditions using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and the new electrochemical frequency modulation (EFM) methods. The obtained results showed that the addition of alanine alone gives a moderate inhibition and acts as an anodic-type inhibitor. The inhibition is due to physical adsorption of alanine on the metal surface. The inhibition efficiency enhances with increasing alanine concentration and immersion time but decreases with rise in temperature. The apparent activation energy, E a , is higher in the presence than in the absence of alanine. Addition of I − ions greatly improves the inhibition efficiency of alanine. The synergistic effect is due to enhanced adsorption of alanine cations by chemisorbed I − anions on the metal surface. The results obtained from polarization, EIS and EFM techniques are in good agreement indicating that EFM method can be used successfully for monitoring corrosion rate of Ni in H 2 SO 4 solution with and without alanine.

  4. The effects of H2SO4 and NaOH solutions on irradiated sawdust for ethanol production

    International Nuclear Information System (INIS)

    Lina, M.R.; Susiana; Siagian, E.G.

    1988-01-01

    The research of gamma irradiated sawdust, which were added H2SO4 and NaOH solutions on fermentation process for ethanol production was investigated. Irradiation doses used were : 0 and 200 kGy, while H2SO4 and NaOH solutions had concentrations of 0,1 and 2% (v/v) and (b/v), with a ratio of sawdust weight and solution volume = 1:3. Fine powder of sawdust with a mesh of 60, was hydrolysed by enzyme (cellulase), S.cerevisiae was a yeast used for fermentation process and fermentation time was 4 hours. From the experimental results showed that irradiation doses up to 200 kGy, could increase the ethanol concentration from sawdust fermentation signivicantly (P= . Irradiation treatment, addition of the solutions and its interaction could not influence the total carbohydrate before and after fermentation. (author). 9 refs, 2 figs, 6 tabs

  5. Aging of the HF-H2SO4 electrolyte used for the electropolishing of niobium superconducting radio frequency cavities: Origins and cure

    Science.gov (United States)

    Eozénou, F.; Berry, S.; Antoine, C.; Gasser, Y.; Charrier, J.-P.; Malki, B.

    2010-08-01

    Electropolishing (EP) in the HF-H2SO4 electrolyte is the most desirable surface treatment for niobium superconducting radio frequency cavities yet demonstrated, in terms of performance and surface finish. However, the efficiency of the electrolyte declines quickly with time (decrease in removal rate, deterioration of the niobium surface, increased sulfur generation). Previous studies at CEA Saclay have highlighted the impact of the water content in EP mixtures rather than the content of dissolved niobium. Knowledge of the electrochemical system was improved thanks to studies using a rotating disk electrode (RDE). Measurements with a RDE give precious information concerning mass transport of the different ionic groups present in the solution. The performed measurements prove that EP is controlled by the diffusion of fluorine ions and the value of the related diffusion coefficient DF- was estimated for different mixtures. Electrochemical impedance spectroscopy (EIS) measurements were also performed with different EP mixtures. Both volt ampere metric and EIS measurements prove the central role of fluorine during EP and show that EP mechanisms evolve with the aging of the bath. Another major problem related to electrolytes is the formation of impurities such as sulfur. We have proved that working at a reduced voltage of 5 V does not alter cavity performance and makes it possible to reduce the undesirable particulate contamination in electrolytes and to increase their lifetime.

  6. Aging of the HF-H_{2}SO_{4} electrolyte used for the electropolishing of niobium superconducting radio frequency cavities: Origins and cure

    Directory of Open Access Journals (Sweden)

    F. Eozénou

    2010-08-01

    Full Text Available Electropolishing (EP in the HF-H_{2}SO_{4} electrolyte is the most desirable surface treatment for niobium superconducting radio frequency cavities yet demonstrated, in terms of performance and surface finish. However, the efficiency of the electrolyte declines quickly with time (decrease in removal rate, deterioration of the niobium surface, increased sulfur generation. Previous studies at CEA Saclay have highlighted the impact of the water content in EP mixtures rather than the content of dissolved niobium. Knowledge of the electrochemical system was improved thanks to studies using a rotating disk electrode (RDE. Measurements with a RDE give precious information concerning mass transport of the different ionic groups present in the solution. The performed measurements prove that EP is controlled by the diffusion of fluorine ions and the value of the related diffusion coefficient D_{F-} was estimated for different mixtures. Electrochemical impedance spectroscopy (EIS measurements were also performed with different EP mixtures. Both volt ampere metric and EIS measurements prove the central role of fluorine during EP and show that EP mechanisms evolve with the aging of the bath. Another major problem related to electrolytes is the formation of impurities such as sulfur. We have proved that working at a reduced voltage of 5 V does not alter cavity performance and makes it possible to reduce the undesirable particulate contamination in electrolytes and to increase their lifetime.

  7. Reductive Leaching Kinetics of Low Grade Manganese Deposits in H2SO4 Solution Using Malonic Acid as Reducing Agent

    OpenAIRE

    Taysser Lasheen; S. A. Abu Elenein; W. A. Saleh; A. H Orabi; D. A Ismaiel

    2014-01-01

    A leaching process was developed to extract manganese and metal values from Alloga manganese concentrate. The preferential leaching process was achieved through reductive leaching in dilute sulfuric acid medium with malonic acid as the reducing agent. Leaching parameters were optimized as 1.0 M H2SO4, 10% malonic acid in solid/liquid ratio 1:10 for 90 min at 80 C and using ore ground to – 74 µm. Under these conditions, the leaching efficiency of manganese reaches 97%, whilst iron dissolution ...

  8. The corrosion inhibition of aluminum and its copper alloys in 1.0 M H2SO4 solution using linear-sodium dodecyl benzene sulfonate as inhibitor

    International Nuclear Information System (INIS)

    Abd El Rehim, Sayed S.; Amin, Mohammed A.; Moussa, S.O.; Ellithy, Abdallah S.

    2008-01-01

    The corrosion inhibition of Al and its two copper alloys are the subject of tremendous technological importance due to the increased industrial applications of these materials. This paper reports the results of potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) measurements on the corrosion inhibition of Al (Al-2.5% Cu and Al-7.0% Cu) alloys in 1.0 M H 2 SO 4 solution carried out in different concentrations of linear-sodium dodecyl benzene sulfonate as an anionic surfactant (LAS) and temperature range from 10 to 60 deg. C. The data revealed that the inhibition efficiency increases with increasing surfactant concentration and time of immersion, and decreases with solution temperature. Energy dispersion X-ray (EDX) observations of the electrode surface confirmed the existence of LAS adsorbed film on the electrode surface. The surfactant acted mainly as cathodic inhibitor. Maximum inhibition efficiency of the surfactant is observed at concentration around its critical micelle concentration (CMC). The inhibition occurs through adsorption of the surfactant on the metal surface without modifying the mechanism of the corrosion process, which tested by UV-spectroscopy. The potential of zero charge (PZC) of aluminum and Al-7.0% Cu was studied by ac-impedance, and the mechanism of adsorption is discussed. The adsorption isotherm is described by Temkin adsorption isotherm. Thermodynamic functions for activation and adsorption process were determined

  9. Electrochemical analysis of the corrosion inhibition effect of trypsin complex on the pitting corrosion of 420 martensitic stainless steel in 2M H2SO4 solution.

    Science.gov (United States)

    Loto, Roland Tolulope

    2018-01-01

    Inhibition effect of trypsin complex (TC) on the pitting corrosion of martensitic stainless steel (type 420) in 1M H2SO4 solution was studied with potentiodynamic polarization, open circuit potential measurement and optical microscopy. TC reduced the corrosion rate of the steel with maximum inhibition efficiency of 80.75%. Corrosion potential shifted anodically due to the electrochemical action of TC. The pitting potential increased from 1.088VAg/AgCl (3M) at 0% TC to 1.365VAg/AgCl(3M) at 4% TC. TC shifts the open circuit corrosion potential from -0.270s at 0% TC concentration to -0.255V at 5% TC. The compound completely adsorbed onto the steel according to Langmuir, Frumkin and Temkin isotherms. ATF-FTIR spectroscopy confirmed the inhibition mode to be through surface coverage. Thermodynamic calculations showed physisorption molecular interaction. Corrosion pits are present on the uninhibited 420 morphology in comparison to TC inhibited surface which slightly deteriorated.

  10. Corrosion polarization behaviour and inhibition of S40977 stainless steel in benzosulfonazole/3 M H2SO4 solution

    Directory of Open Access Journals (Sweden)

    Roland Tolulope Loto

    2017-12-01

    Full Text Available Benzosulfonazole was evaluated for its corrosion inhibition effect on S40977 stainless steel in 3 M H2SO4 solution through potentiodynamic polarization, open circuit potential measurement, optical microscopy and IR spectroscopy. Results obtained showed the effective performance of the compound with values of 77.33%–88.32% inhibition efficiency, at 0.25%–1.25% inhibitor concentration from electrochemical analysis. Corrosion potential value decreased from −0.359 V to −0.306 V upon addition of the compound at 0.25% concentration, which decreased progressively to −0.278 at 1.25% concentration. Identified functional groups of alcohols, phenols, amines, amides, carboxylic acids, aliphatic amines, esters and ethers within the compound completely adsorbed onto the steel from analysis of the adsorption spectra while others decreased in intensity due to partial adsorption. Thermodynamic calculations showed the cationic adsorption to be through chemisorption mechanism according to Langmuir, Freundlich and Temkin adsorption isotherms. Micro-analytical images showed a severely corroded morphology with corrosion pits in the absence of benzosulfonazole which contrast the images obtained with the inhibitor addition. The compound was determined to be mixed type inhibition. Keywords: Corrosion, Inhibitor, Benzosulfonazole, Sulphuric acid

  11. Effect of electrolyte composition on the active-to-passive transition behavior of 2205 duplex stainless steel in H2SO4/HCl solutions

    International Nuclear Information System (INIS)

    Lo, I-H.; Fu Yan; Lin, C.-J.; Tsai, W.-T.

    2006-01-01

    Selective dissolution could occur in duplex stainless steels (DSSs) due to the difference in chemical composition between the two constituent phases. In this study, the effect of H 2 SO 4 /HCl composition on the selective dissolution behavior was investigated. The results indicated that there were two distinct peaks appeared in the active-to-passive transition region in the polarization curve. The peak appeared at a lower potential region was associated with the preferential dissolution of ferrite phase while that for austenite at a higher potential. In the concentration ranges of 0.25-2 M of H 2 SO 4 and 0.25-2 M of HCl, the magnitude of the peak anodic current density and the resolution between these two peaks greatly depended on the composition of H 2 SO 4 /HCl. However, the anodic peaks corresponding to the respective dissolutions of ferrite and austenite became less distinguishable when the concentrations of HCl exceeded 1.2 M. Image analysis using scanning electron microscopy (SEM) was performed to confirm the selective dissolution of each constituent phase after potentiostatic polarization at the respective anodic peak potential

  12. Corrosion behaviour of groundnut shell ash and silicon carbide hybrid reinforced Al-Mg-Si alloy matrix composites in 3.5% NaCl and 0.3M H2SO4 solutions

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayo ALANEME

    2015-05-01

    Full Text Available The corrosion behaviour of Al-Mg-Si alloy based composites reinforced with groundnut shell ash (GSA and silicon carbide (SiC was investigated. The aim is to assess the corrosion properties of Al-Mg-Si alloy based hybrid reinforced composites developed using different mix ratios of GSA (a cheaply processed agro waste derivative which served as partial replacement for SiC and SiC as reinforcing materials. GSA and SiC mixed in weight ratios 0:1, 1:3, 1:1, 3:1, and 1:0 were utilized to prepare 6 and 10 wt% of the reinforcing phase with Al‐Mg‐Si alloy as matrix using two‐step stir casting method. Mass loss and corrosion rate measurement was used to study the corrosion behaviour of the produced composites in 3.5% NaCl and 0.3M H2SO4 solutions. The results show that the Al-Mg-Si alloy based composites containing 6 and 10 wt% GSA and SiC in varied weight ratios were resistant to corrosion in 3.5% NaCl solution. The composites were however more susceptible to corrosion in 0.3M H2SO4 solution (in comparison with the 3.5% NaCl solution. It was noted that the Al-Mg-Si/6 wt% GSA-SiC hybrid composite grades containing GSA and SiC in weight ratio 1:3 and 3:1 respectively exhibited superior corrosion resistance in the 0.3M H2SO4 solution compared to other composites produced for this series. In the case of the Al-Mg-Si/10 wt% GSA-SiC hybrid composite grades, the corrosion resistance was relatively superior for the composites containing a greater weight ratio of GSA (75% and 100% in 0.3M H2SO4 solution.

  13. Effect of ortho-substituted aniline on the corrosion protection of aluminum in 2 mol/L H2SO4 solution

    KAUST Repository

    El-Deeb, Mohamed M.; Alshammari, Hamed M.; Abdel-Azeim, Safwat

    2017-01-01

    Corrosion protection of aluminum in 2 mol/L HSO solution is examined in the presence of ortho-substituted aniline derivatives using potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Density function theory (DFT

  14. Effect of ortho-substituted aniline on the corrosion protection of aluminum in 2 mol/L H2SO4 solution

    KAUST Repository

    El-Deeb, Mohamed M.

    2017-02-13

    Corrosion protection of aluminum in 2 mol/L HSO solution is examined in the presence of ortho-substituted aniline derivatives using potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Density function theory (DFT) calculations are performed to investigate the aluminum-electrolyte interface relationship in the absence and presence of both ortho-substituted aniline derivatives and sulphate anions, as well as their roles in the protection efficiency at the atomic level. Our results show that ortho-aniline derivatives are good inhibitors and that their efficiencies improved as the concentration increased. SEM-EDX analysis is used to confirm the adsorption thermodynamics of the studied compounds on the aluminum surface. The best inhibitory effect is exhibits in the presence of the methyl group in ortho-position followed by ortho-carboxilic compared to aniline. The adsorption of these compounds on the aluminum surface is well described by Langmuir adsorption isotherm as well as the experimental and the theoretical adosrption energies are in a good agreement. DFT calculations also show that the interaction between the inhibitors and the aluminum surface is mainly electrostatic and depends on the type of the ortho-substituted group in addition to the sulphate anions.

  15. Passivity of AISI 321 stainless steel in 0.5 M H2SO4 solution studied by Mott–Schottky analysis in conjunction with the point defect model

    Directory of Open Access Journals (Sweden)

    A. Fattah-alhosseini

    2016-11-01

    Full Text Available The passivity of AISI 321 stainless steel in 0.5 M H2SO4 solution, in the steady-state condition, has been explored using electrochemical impedance spectroscopy (EIS and Mott–Schottky analysis. Based on the Mott–Schottky analysis in conjunction with the point defect model (PDM, it was shown that the calculated donor density decreases exponentially with increasing passive film formation potential. The thickness of the passive film was increased linearly with the formation potential. These observations were consistent with the predictions of the PDM, noting that the point defects within the passive film are metal interstitials, oxygen vacancies, or both.

  16. Indeno-1-one [2,3-b]quinoxaline as an effective inhibitor for the corrosion of mild steel in 0.5 M H2SO4 solution

    International Nuclear Information System (INIS)

    Obot, I.B.; Obi-Egbedi, N.O.

    2010-01-01

    Indeno-1-one [2,3-b] quinoxaline (INQUI), synthesized in our laboratory, was tested as inhibitor for the corrosion of mild steel in 0.5 M H 2 SO 4 using gravimetric method at 30 o C. The inhibitor (INQUI) showed about 81% inhibition efficiency (E (%)) at an optimum concentration of 10 x 10 -6 M. The inhibition efficiency increases with increase in inhibitor concentration but decreases with increase in immersion time. The adsorption of the inhibitor on the mild steel in the acid solution was found to accord with Temkin's adsorption isotherm. The calculated value of the free energy for the adsorption process, ΔG ads , reveals a strong chemisorbed bond between the inhibitor and mild steel surface and a spontaneous adsorption of the inhibitor on the mild steel surface. Density functional theory (DFT) proves that INQUI molecule is adsorbed on the mild steel surface by the most negatively charged nitrogen and oxygen atoms.

  17. Analysis of electrochemical noise (ECN) data in time and frequency domain for comparison corrosion inhibition of some azole compounds on Cu in 1.0 M H2SO4 solution

    Science.gov (United States)

    Ramezanzadeh, B.; Arman, S. Y.; Mehdipour, M.; Markhali, B. P.

    2014-01-01

    In this study, the corrosion inhibition properties of two similar heterocyclic compounds namely benzotriazole (BTA) and benzothiazole (BNS) inhibitors on copper in 1.0 M H2SO4 solution were studied by electrochemical techniques as well as surface analysis. The results showed that corrosion inhibition of copper largely depends on the molecular structure and concentration of the inhibitors. The effect of DC trend on the interpretation of electrochemical noise (ECN) results in time domain was evaluated by moving average removal (MAR) method. Accordingly, the impact of square and Hanning window functions as drift removal methods in frequency domain was studied. After DC trend removal, a good trend was observed between electrochemical noise (ECN) data and the results obtained from EIS and potentiodynamic polarization. Furthermore, the shot noise theory in frequency domain was applied to approach the charge of each electrochemical event (q) from the potential and current noise signals.

  18. Monte-Carlo Simulation of γ-ray and Fast Neutron Radiolysis of Liquid Water and 0.4 M H2SO4 Solutions at Temperatures up to 325 oC

    International Nuclear Information System (INIS)

    Sunaryo, G.R.; Jintana, M.; Gerin, J.P.J.

    2011-01-01

    Monte-Carlo simulations were used to study the radiolysis of liquid water at 25-325 o C when subjected to low linear energy transfer (LET) of 60 Co γ-ray radiation and fast neutrons of 2 and 0.8 MeV. The energy deposited in the early stage of 60 Co γ--ray irradiation was approximated by considering short segments (∼150 μm) of 300 MeV proton tracks, corresponding to an average LET of ∼0.3 keV/μm. In case of 2 MeV fast neutrons, the energy deposited was considered by using short segments (∼5 μm) of energy at 1.264, 0.465, 0.171, 0.063 and 0.24 MeV. 0.8 MeV fast neutrons were approximated by 0.505, 0.186, 0.069 and 0.025 MeV protons. The effect of 0.4 M H 2 SO 4 solution on radiolysis was also studied by this method for both 60 Co γ-rays and 0.8 MeV fast neutrons. The simulated results at the time of 10 -7 s after irradiation were obtained and compared with the available experimental results published by other researchers to be in excellent agreement with them over the entire temperature ranges and radiation sources studied. Except for g(H 2 ) that increase with temperature rises, the general behaviors of higher radical products and lower molecular products at higher temperatures were obtained. The LET effect is also validated by this study, showing that the increase in LET would yield higher molecular and lower radical products. Studies on 0.4 M H 2 SO 4 solutions also show good agreement between the computed and experimental data for γ-ray irradiation: the presence of 0.4 M H + , except for g(H 2 ) that gives lower value at 25 o C and higher value at 325 o C, gives the higher values for radicals and g(H 2 O 2 ) at 25 o C and lower values at 325 o C, compared with that for neutral water. The computed data show good agreement with the experimental data for 0.4 M H 2 SO 4 solutions induced by 0.8 MeV fast neutrons, except for g(H 2 ) and g(H · ) that gives good agreement up to 50 o C, then the opposite tendencies with the further temperature rises

  19. Synergism between rare earth cerium(IV) ion and vanillin on the corrosion of steel in H2SO4 solution: Weight loss, electrochemical, UV-vis, FTIR, XPS, and AFM approaches

    International Nuclear Information System (INIS)

    Li Xianghong; Deng Shuduan; Fu Hui; Mu Guannan; Zhao Ning

    2008-01-01

    The synergism between rare earth cerium(IV) ion and vanillin (4-hydroxy-3-methoxy-benzaldehyde) on the corrosion of cold rolled steel (CRS) in 1.0 M H 2 SO 4 solution at five temperatures ranging from 20 to 60 deg. C was first studied by weight loss and potentiodynamic polarization methods. The inhibited solutions were analyzed by ultraviolet and visible spectrophotometer (UV-vis). The adsorbed film of CRS surface containing optimum doses of the blends Ce 4+ -vanillin was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). The results revealed that vanillin had a moderate inhibitive effect, and the inhibition efficiency (IE) increased with the vanillin concentration. The adsorption of vanillin obeyed Temkin adsorption isotherm. Polarization curves showed that vanillin was a mixed-type inhibitor in sulfuric acid, while prominently inhibited the cathodic reaction. For the cerium(IV) ion, it had a negligible effect, and the maximum IE was only about 20%. However, incorporation of Ce 4+ with vanillin improved significantly the inhibition performance. The IE for Ce 4+ in combination with vanillin was higher than the summation of IE for single Ce 4+ and single vanillin, which was synergism in nature. A high inhibition efficiency, 98% was obtained by a mixture of 25-200 mg l -1 vanillin and 300-475 mg l -1 Ce 4+ . UV-vis showed that the new complex of Ce 4+ -vanillin was formed in 1.0 M H 2 SO 4 for Ce 4+ combination with vanillin. Polarization studies showed that the complex of Ce 4+ -vanillin acted as a mixed-type inhibitor, which drastically inhibits both anodic and cathodic reactions. FTIR and XPS revealed that a protective film formed in the presence of both vanillin and Ce 4+ was composed of cerium oxide and the complex of Ce 4+ -vanillin. The synergism between Ce 4+ and vanillin could also be evidenced by AFM images. Depending on the results, the synergism mechanism was discussed

  20. Broader energy distribution of CO adsorbed at polycrystalline Pt electrode in comparison with that at Pt(111) electrode in H_2SO_4 solution confirmed by potential dependent IR/visible double resonance sum frequency generation spectroscopy

    International Nuclear Information System (INIS)

    Yang, Shuo; Noguchi, Hidenori; Uosaki, Kohei

    2017-01-01

    Highlights: • Electrochemical SFG spectroscopy is an efficient in situ probe of electronic structure at electrochemical interface. • Electrooxidation performances of CO adsorbed on polycrystalline Pt and Pt(111) electrodes were compared. • The enhanced SFG signal of CO on Pt electrodes was observed due to a vibrational-electronic double resonance effect. • The broader energy distribution of 5sa state of CO on polycrystalline Pt than on Pt(111) is proved by SFG results. - Abstract: Electrochemical cyclic voltammetry and potential dependent double resonance sum frequency generation (DR-SFG) spectroscopy were performed on CO adsorbed on polycrystalline Pt and Pt(111) electrodes in H_2SO_4 solution to examine the effect of substrate on the electronic structure of CO. The dependence of SFG intensity on potential and visible energy for atop CO band was observed on both polycrystalline and single crystalline Pt electrodes. Enhancement of the SFG intensity was determined to be a direct result of a surface electronic resonance of the visible/SF light with the electronic transition from Fermi level of Pt to the 5σ_a anti-bonding state of adsorbed CO, in agreement with previous results. Interestingly, when compared to the Pt(111) electrode, the distribution width of the intensity enhancement region on polycrystalline Pt is broader than on Pt(111). This suggests that the energy distribution of the 5σ_a state of CO on polycrystalline Pt surface is broader than that on Pt(111) due to the complex surface structure of the polycrystalline Pt electrode.

  1. Dispersion capacitive de l'interface H 2 SO 4 /Pt | Hammadi ...

    African Journals Online (AJOL)

    Capacitive dispersion of Pt/H2SO4 interface. Impedance measurements by EIS and voltammograms measurements by CV on pretreated Pt electrodes immersed in an electrolytic solution of 0.5M H2SO4 are presented. Two electrochemical pretreatment techniques of the WE (thin Pt wire) are used: cleaning and etching.

  2. Improved corrosion and wear resistance of laser alloyed Zn-Sn-Ti composite coatings on UNS G10150 steel in 0.5 M H2SO4 solution

    CSIR Research Space (South Africa)

    Fatoba, OS

    2016-03-01

    Full Text Available were cut to corrosion coupons, immersed in sulfuric acid (0.5M H(SUB2)SO(SUB4)) solution at 300 C using electrochemical technique and investigated for its corrosion behavior. The morphologies and microstructures of the developed coatings and uncoated...

  3. H2SO4-HNO3-H2O ternary system in the stratosphere

    Science.gov (United States)

    Kiang, C. S.; Hamill, P.

    1974-01-01

    Estimation of the equilibrium vapor pressure over the ternary system H2SO4-HNO3-H2O to study the possibility of stratospheric aerosol formation involving HNO3. It is shown that the vapor pressures for the ternary system H2SO4-HNO3-H2O with weight composition around 70-80% H2SO4, 10-20% HNO3, 10-20% H2O at -50 C are below the order of 10 to the minus 8th mm Hg. It is concluded that there exists more than sufficient nitric acid and water vapor in the stratosphere to participate in ternary system aerosol formation at -50 C. Therefore, HNO3 should be present in stratospheric aerosols, provided that H2SO4 is also present.

  4. Densities and apparent molar volumes of atmospherically important electrolyte solutions. 1. The solutes H2SO4, HNO3, HCl, Na2SO4, NaNO3, NaCl, (NH4)2SO4, NH4NO3, and NH4Cl from 0 to 50 °C, including extrapolations to very low temperature and to the pure liquid state, and NaHSO4, NaOH, and NH3 at 25 °C.

    Science.gov (United States)

    Clegg, S L; Wexler, A S

    2011-04-21

    Calculations of the size and density of atmospheric aerosols are complicated by the fact that they can exist at concentrations highly supersaturated with respect to dissolved salts and supercooled with respect to ice. Densities and apparent molar volumes of solutes in aqueous solutions containing the solutes H(2)SO(4), HNO(3), HCl, Na(2)SO(4), NaNO(3), NaCl, (NH(4))(2)SO(4), NH(4)NO(3), and NH(4)Cl have been critically evaluated and represented using fitted equations from 0 to 50 °C or greater and from infinite dilution to concentrations saturated or supersaturated with respect to the dissolved salts. Using extrapolated densities of high-temperature solutions and melts, the relationship between density and concentration is extended to the hypothetical pure liquid solutes. Above a given reference concentration of a few mol kg(-1), it is observed that density increases almost linearly with decreasing temperature, and comparisons with available data below 0 °C suggest that the fitted equations for density can be extrapolated to very low temperatures. As concentration is decreased below the reference concentration, the variation of density with temperature tends to that of water (which decreases as temperature is reduced below 3.98 °C). In this region below the reference concentration, and below 0 °C, densities are calculated using extrapolated apparent molar volumes which are constrained to agree at the reference concentrations with an equation for the directly fitted density. Calculated volume properties agree well with available data at low temperatures, for both concentrated and dilute solutions. Comparisons are made with literature data for temperatures of maximum density. Apparent molar volumes at infinite dilution are consistent, on a single ion basis, to better than ±0.1 cm(3) mol(-1) from 0 to 50 °C. Volume properties of aqueous NaHSO(4), NaOH, and NH(3) have also been evaluated, at 25 °C only. In part 2 of this work (ref 1 ) an ion interaction (Pitzer

  5. Inhibitor for the Corrosion of Mild Steel in H 2 SO 4 | Patel | South ...

    African Journals Online (AJOL)

    An extract of Terminalia chebula fruits was investigated as a corrosion inhibitor of mild steel in 0.5 M H2SO4 by means of conventional mass loss, electrochemical polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The mass loss results showed that the extract of Terminalia chebula is ...

  6. High yield and facile microwave-assisted synthesis of conductive H_2SO_4 doped polyanilines

    International Nuclear Information System (INIS)

    Gizdavic-Nikolaidis, Marija R.; Jevremovic, Milutin M.; Milenkovic, Maja; Allison, Morgan C.; Stanisavljev, Dragomir R.; Bowmaker, Graham A.; Zujovic, Zoran D.

    2016-01-01

    The microwave-assisted synthesis of polyaniline (PANI) was performed using ammonium persulphate (APS) as oxidizing agent in 0.5 M–2.5 M concentration range of aqueous sulphuric acid (H_2SO_4) at 93 W applied microwave power of 10 min duration. The microwave (MW) synthesized PANIs had 3 times higher yield in comparison to PANI samples prepared using a classical method, CS (0 W MW power) at the same temperature for 10 min synthesis duration period. Fourier Transform Infrared (FTIR) and UV–Vis spectroscopies confirmed the formation of PANI structure in all products. The influence of H_2SO_4 acid dopant on the spin concentration of MW and CS H_2SO_4 doped PANI samples were examined by EPR spectroscopy, while the morphological characteristics were investigated by using scanning electron microscopy (SEM). XRD results showed amorphous phases in both MW and CS H_2SO_4 doped PANI samples. Conductivity measurements revealed ∼1.5 times higher conductivity values for MW H_2SO_4 doped PANI samples in comparison with PANI samples prepared by the CS method under same condition. The influence of sulfate anion in comparison to chloride anion as a dopant on morphological, dopant levels and conductivity properties of MW PANI samples were also investigated. - Highlights: • Nanoporous microwave synthesized doped polyanilines as chemical sensor material. • Morphology and physical properties of polyanilines depend on acid concentration. • Spin concentration is determined by the nature of the polyaniline synthesis.

  7. Method of dosing H2SO4 in uranium ores leaching

    International Nuclear Information System (INIS)

    Jusko, J.; Skocny, J.

    1977-01-01

    A description is presented of the control circuit and its function. Dosing is controlled in a discontinuous manner using H 2 SO 4 and slurry ratio control. The flow volume of each fraction is measured by an induction flowmeter. The control circuit mostly consists of mass produced instruments and is very reliable while requiring minimum attendance. The principle of the system is suitable for any discontinuous dosing where the output fraction concentration is difficult to analyze automatically. (M.K.)

  8. Experimental study of H2SO4 aerosol nucleation at high ionization levels

    DEFF Research Database (Denmark)

    Tomicic, Maja; Bødker Enghoff, Martin; Svensmark, Henrik

    2018-01-01

    One hundred and ten direct measurements of aerosol nucleation rate at high ionization levels were performed in an 8 m3 reaction chamber. Neutral and ion-induced particle formation from sulfuric acid (H2SO4) was studied as a function of ionization and H2SO4 concentration. Other species that could...... have participated in the nucleation, such as NH3 or organic compounds, were not measured but assumed constant, and the concentration was estimated based on the parameterization by Gordon et al. (2017). Our parameter space is thus [H2SO4]  = 4×106 − 3×107 cm−3, [NH3+ org]  =  2.2 ppb, T = 295 K, RH......  =  38 %, and ion concentrations of 1700–19 000 cm−3. The ion concentrations, which correspond to levels caused by a nearby supernova, were achieved with gamma ray sources. Nucleation rates were directly measured with a particle size magnifier (PSM Airmodus A10) at a size close to critical cluster size...

  9. Optimization of H2SO4-catalyzed hydrothermal pretreatment of rapeseed straw for bioconversion to ethanol

    DEFF Research Database (Denmark)

    Xuebin, Lu; Zhang, Y.; Angelidaki, Irini

    2009-01-01

    A central composite design of response surface method was used to optimize H2SO4-catalyzed hydrothermal pretreatment of rapeseed straw, in respect to acid concentration (0.5-2%), treatment time (5-20 min) and solid content (10-20%) at 180 degrees C. Enzymatic hydrolysis and fermentation were also...... content for 10 min at 180 degrees C was found to be the most optimal condition for pretreatment of rapeseed straw for ethanol production. After pretreatment at the optimal condition and enzymatic hydrolysis, 75.12% total xylan and 63.17% total glucan were converted to xylose and glucose, respectively...

  10. Experimental study of H2SO4 aerosol nucleation at high ionization levels

    Directory of Open Access Journals (Sweden)

    M. Tomicic

    2018-04-01

    Full Text Available One hundred and ten direct measurements of aerosol nucleation rate at high ionization levels were performed in an 8 m3 reaction chamber. Neutral and ion-induced particle formation from sulfuric acid (H2SO4 was studied as a function of ionization and H2SO4 concentration. Other species that could have participated in the nucleation, such as NH3 or organic compounds, were not measured but assumed constant, and the concentration was estimated based on the parameterization by Gordon et al. (2017. Our parameter space is thus [H2SO4]  = 4×106 − 3×107 cm−3, [NH3+ org]  =  2.2 ppb, T = 295 K, RH  =  38 %, and ion concentrations of 1700–19 000 cm−3. The ion concentrations, which correspond to levels caused by a nearby supernova, were achieved with gamma ray sources. Nucleation rates were directly measured with a particle size magnifier (PSM Airmodus A10 at a size close to critical cluster size (mobility diameter of  ∼  1.4 nm and formation rates at a mobility diameter of  ∼  4 nm were measured with a CPC (TSI model 3775. The measurements show that nucleation increases by around an order of magnitude when the ionization increases from background to supernova levels under fixed gas conditions. The results expand the parameterization presented in Dunne et al. (2016 and Gordon et al. (2017 (for [NH3 + org]  =  2.2 ppb and T = 295 K to lower sulfuric acid concentrations and higher ion concentrations. The results make it possible to expand the parameterization presented in Dunne et al. (2016 and Gordon et al. (2017 to higher ionization levels.

  11. Corrosion Inhibition and Adsorption Characteristics of Tarivid on Mild Steel in H2SO4

    Directory of Open Access Journals (Sweden)

    N. O. Eddy

    2010-01-01

    Full Text Available The corrosion inhibition and adsorption characteristics of (+/--9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylic acid (Tarivid on the corrosion of mild steel has been studied using thermometric and gasometric methods. The study reveals that tarivid inhibits the corrosion of mild steel in H2SO4. The values of inhibition efficiency of tarivid were found to increase as its concentration increased but decreased with increase in temperature. Activation energies of the inhibited corrosion of mild steel ranged from 39.05 to 50.61 kJ/mol. Values of enthalpy change and free energy of adsorption were negative which indicated exothermic and spontaneous adsorption process. Physical adsorption mechanism is proposed from the obtained kinetic and thermodynamic parameters. Langmuir adsorption isotherm model is obeyed from the fit of the experimental data.

  12. The Effect of H2SO4 Concentration on the Ionic Conductivity of Liquid PMMA Oligomer

    International Nuclear Information System (INIS)

    Norashima Kamaluddin; Famiza Abdul Latif; Han, C.C.; Ruhani Ibrahim; Sharil Fadli Mohamad Zamri; Norashima Kamaluddin; Famiza Abdul Latif; Han, C.C.; Ruhani Ibrahim; Sharil Fadli Mohamad Zamri

    2015-01-01

    To date gel and film type polymer electrolytes have been widely synthesized due to their wide range of electrical properties. However these types of polymer electrolytes exhibit poor mechanical stability and poor electrode-electrolyte contact hence deprive the overall performance of a battery system. Therefore, in order to indulge the advantages of polymer as electrolyte, a new class of polymer electrolyte was synthesized and investigated. In this study, liquid poly(methyl methacrylate) (PMMA) electrolyte was synthesized using the simplest free radical polymerization technique using benzoyl peroxide as the initiator. At this stage, it was found that this liquid PMMA oligomer (MW=3000 g/ mole) has a potential as electrolyte in electrochemical devices. It was found that an ionic conductivity of ∼10 -7 S/ cm at room temperature can be achieved when only small volume of high molarity of sulfuric acid (H 2 SO 4 ) was doped in the liquid PMMA oligomer. The properties of this liquid PMMA oligomer were further investigated using Fourier Transform Infrared Spectroscopy (FTIR). (author)

  13. Enhanced thermoelectric properties of PEDOT/PSS/Te composite films treated with H2SO4

    International Nuclear Information System (INIS)

    Song, Haijun; Cai, Kefeng; Shen, Shirley

    2016-01-01

    Firstly, tellurium (Te) nanorods with a high Seebeck coefficient have been integrated into a conducting polymer PEDOT/PSS to form PEDOT/PSS/Te composite films. The Seebeck coefficient of the PEDOT/PSS/Te (90 wt.%) composite films is ~191 μV/K, which is about 13 times greater than that of pristine PEDOT/PSS. Then, H 2 SO 4 treatment has been used to further tune the thermoelectric properties of the composite films by adjusting the doping level and increasing the carrier concentration. After the acid treatment, the electrical conductivity of the composite films has increased from 0.22 to 1613 S/cm due to the removal of insulating PSS and the structural rearrangement of PEDOT. An optimized power factor of 42.1 μW/mK 2 has been obtained at room temperature for a PEDOT/PSS/Te (80 wt.%) sample, which is about ten times larger than that of the untreated PEDOT/PSS/Te composite film.

  14. Evaluation of in vitro and in vivo tests for surface-modified titanium by H2SO4 and H2O2 treatment

    Science.gov (United States)

    Lee, Min-Ho; Park, Il-Song; Min, Kwan-Sik; Ahn, Seung-Geun; Park, Ju-Mi; Song, Kwang-Yeob; Park, Charn-Woon

    2007-04-01

    Titanium is widely used as an implant material for artificial teeth. Furthermore, various studies have examined surface treatment with respect to the formation of a fine passive film on the surface of commercial titanium and its alloys and to improve the bioactivity with bone. However, there is insufficient data about the biocompatibility of implant materials in the body. The purpose of this study was to examine whether surface modification affects the precipitation of apatite on titanium metal. Specimens were chemically washed for 2 min in a 1∶1∶1.5 (vol.%) mixture of 48 %HF, 60%HNO3 and distilled water. The specimens were then chemically treated with a solution containing 97%H2SO4 and 30%H2O2 at the ratio of 1∶1 (vol.%) at 40°C for 1h, and subsequently heat-treated at 400°C for 1h. All the specimens were immersed in HBSS with pH 7.4 at 36.5°C for 15d, and the surface was examined with TF-XRD, SEM, EDX and XPS. In addition, specimens of commercial pure Ti, with and without surface treatment, were implanted in the abdominal connective tissue of mice for 28 d. Conventional aluminum and stainless steel 316L were also implanted for comparison. An amorphous titania gel layer was formed on the titanium surface after the titanium specimen was treated with a solution of H2SO4 and H2O2. The average roughness was 2.175 μm after chemical surface treatment. The amorphous titania was subsequently transformed into anatase by heat treatment at 400°C for 1h. The average thickness of the fibrous capsule surrounding the specimens implanted in the connective tissue was 47.1μm in the chemically treated Ti, and 52.2, 168.7 and 101.9μm, respectively, in the untreated commercial pure Ti, aluminum and stainless steel 316L.

  15. Promotion of H2 production by microwave-assisted treatment of water hyacinth with dilute H2SO4 through combined dark fermentation and photofermentation

    International Nuclear Information System (INIS)

    Cheng, Jun; Xia, Ao; Su, Huibo; Song, Wenlu; Zhou, Junhu; Cen, Kefa

    2013-01-01

    Highlights: • Water hyacinth is microwaved with dilute H 2 SO 4 to improve enzymatic hydrolysis. • Hydrolyzed hyacinth is fermented by hydrogenogens to improve dark H 2 yield. • Nearly 100% glucose and most arabinose in hydrolysate are used in dark fermentation. • H 2 yield from hyacinth via combined fermentation is 75.2% of theoretical H 2 yield. - Abstract: Water hyacinth was treated with microwave-assisted dilute H 2 SO 4 to improve saccharification before enzymatic hydrolysis and H 2 production during dark fermentation. A maximum reducing sugar (RS) yield of 64.4 g/100 g total volatile solid (TVS) (96.1% of the theoretical RS yield) was achieved when water hyacinth was treated through microwave heating with 1% dilute H 2 SO 4 for 15 min at 140 °C and then enzymatically hydrolyzed for 72 h. During enzymatic hydrolysis, glucose was efficiently produced from the hydrolysis of cellulose that resulted from the disruption of the lignocellulosic structure of water hyacinth after microwave-assisted H 2 SO 4 treatment. When the hydrolyzed water hyacinth was inoculated with H 2 -producing bacteria to produce H 2 during dark fermentation, a maximum H 2 yield of 112.3 ml/g TVS was obtained. The major sugar compositions in the residual solution from dark fermentation were xylose and cellobiose (total RS utilization efficiency: 88.5%). Through a combination of dark fermentation and photofermentation, the maximum H 2 yield from water hyacinth was significantly increased from 112.3 ml/g TVS to 751.5 ml/g TVS, which is 75.2% of the theoretical H 2 yield

  16. Sorption behaviour of uranium and thorium on hydrons tin oxide from aqueous and mixed-solvent H2SO4 media

    International Nuclear Information System (INIS)

    Misak, N.Z.; Salema, H.N.; El-Naggar, J.M.

    1983-01-01

    At pH values > about 2 in 10 -3 -10 -2 M aqueous sulphate solutions, uranium seems to be sorbed by hydrous tin oxide mainly as cations, while thorium is sorced as cations and as the neutral complex. At pH values of about 1.1-1.4, both uranium and thorium seem to be mainly sorbed as the neutral complexes. while at lower pH values, sorption of anionic commplexes comes into play. The sorption of uranium generally increased progressively on addition of increasing amounts of methanol, ethanol or acetone. The sorption of thorium decreases a little at 0.01 N H 2 SO 4 and increases a little at 0.5 N H 2 SO 4 on adding the organic solvents. At 0.1 N H 2 SO 4 , the addition of 20percent of the organic solvents brings the sorption of thorium to almost negligible values, which seems to offer an attractive means for U/Th separation. (author)

  17. Removal of Procion Red dye from colored effluents using H2SO4-/HNO3-treated avocado shells (Persea americana) as adsorbent.

    Science.gov (United States)

    Georgin, Jordana; da Silva Marques, Bianca; da Silveira Salla, Julia; Foletto, Edson Luiz; Allasia, Daniel; Dotto, Guilherme Luiz

    2018-03-01

    The treatment of colored effluents containing Procion Red dye (PR) was investigated using H 2 SO 4 and HNO 3 modified avocado shells (Persea americana) as adsorbents. The adsorbent materials (AS-H 2 SO 4 and AS-HNO 3 ) were properly characterized. The adsorption study was carried out considering the effects of adsorbent dosage and pH. Kinetic, equilibrium, and thermodynamic aspects were also evaluated. Finally, the adsorbents were tested to treat simulated dye house effluents. For both materials, the adsorption was favored using 0.300 g L -1 of adsorbent at pH 6.5, where, more than 90% of PR was removed from the solution. General order model was able to explain the adsorption kinetics for both adsorbents. The Sips model was adequate to represent the isotherm data, being the maximum adsorption capacities of 167.0 and 212.6 mg g -1 for AS-H 2 SO 4 and AS-HNO 3 , respectively. The adsorption processes were thermodynamically spontaneous, favorable (- 17.0 Avocado shells, after a simple acid treatment, can be a low-cost option to treat colored effluents.

  18. Investigation of nucleation kinetics in H2SO4 vapor through modeling of gas phase kinetics coupled with particle dynamics

    Science.gov (United States)

    Carlsson, Philip T. M.; Zeuch, Thomas

    2018-03-01

    We have developed a new model utilizing our existing kinetic gas phase models to simulate experimental particle size distributions emerging in dry supersaturated H2SO4 vapor homogeneously produced by rapid oxidation of SO2 through stabilized Criegee-Intermediates from 2-butene ozonolysis. We use a sectional method for simulating the particle dynamics. The particle treatment in the model is based on first principles and takes into account the transition from the kinetic to the diffusion-limited regime. It captures the temporal evolution of size distributions at the end of the ozonolysis experiment well, noting a slight underrepresentation of coagulation effects for larger particle sizes. The model correctly predicts the shape and the modes of the experimentally observed particle size distributions. The predicted modes show an extremely high sensitivity to the H2SO4 evaporation rates of the initially formed H2SO4 clusters (dimer to pentamer), which were arbitrarily restricted to decrease exponentially with increasing cluster size. In future, the analysis presented in this work can be extended to allow a direct validation of quantum chemically predicted stabilities of small H2SO4 clusters, which are believed to initiate a significant fraction of atmospheric new particle formation events. We discuss the prospects and possible limitations of the here presented approach.

  19. Isatin derivatives as a non-toxic corrosion inhibitor for mild steel in 20% H2SO4

    International Nuclear Information System (INIS)

    Ansari, K.R.; Quraishi, M.A.; Singh, Ambrish

    2015-01-01

    Highlights: • Mild steel protection in 20% H 2 SO 4 by TZs. • Potentiodynamic polarization curves reveal that the actions of TZs are mixed type but cathodically predominant. • The adsorption of TZs obeys the Langmuir adsorption isotherm. • Examination of surface morphology by SEM and EDX. • Correlation between experimental and quantum chemical results. - Abstract: The corrosion inhibition action of Isatin-β-thiosemicarbzone derivatives namely 1-Benzylidene-5-(2-oxoindoline-3-ylidene) Thiocarbohydrazone (TZ-1) and 1-(4-Methylbenzylidene)-5-(2-oxoindolin-3-ylidene) Thiocarbohydrazone (TZ-2) was studied on mild steel surface in 20% H 2 SO 4 by gravimetric measurements, Electrochemical measurements (EIS and Tafel), SEM, EDX and quantum chemical methods. Potentiodynamic polarization curves reveal that the TZs act as mixed type inhibitors exhibiting predominantly cathodic behavior. The adsorption of TZs obeys the Langmuir adsorption isotherm. The thermodynamic parameters (E a , K ads , ΔG° ads ) were also computed and discussed

  20. INHIBITION EFFECT OF FLAVONOID EXTRACT OF Euphorbia Guyoniana ON THE CORROSION OF MILD STEEL IN H2SO4 MEDIUM

    OpenAIRE

    S. Chihi; N. Gherraf; B. Alabed; S. Hameurlain

    2009-01-01

    The influence of flavonoids extracts of three parts of Euphorbia Guyoniana towards the corrosion of type API 5L X52 steel in 15% H2SO4 has been evaluated by weight loss method and polarization technique. The results showed that extracts are a good inhibitors for API 5L X52 steel in this medium. The corrosion inhibition efficiency increases on increasing plant extracts concentration. The inhibition is attributed to the adsorption of the surface of the metal. Potentiodynamic polarization result...

  1. Laboratory studies of H2SO4/H2O binary homogeneous nucleation from the SO2+OH reaction: evaluation of the experimental setup and preliminary results

    Directory of Open Access Journals (Sweden)

    M. Kulmala

    2008-08-01

    Full Text Available Binary homogeneous nucleation (BHN of sulphuric acid and water (H2SO4/H2O is one of the most important atmospheric nucleation processes, but laboratory observations of this nucleation process are very limited and there are also large discrepancies between different laboratory studies. The difficulties associated with these experiments include wall loss of H2SO4 and uncertainties in estimation of H2SO4 concentration ([H2SO4] involved in nucleation. We have developed a new laboratory nucleation setup to study H2SO4/H2O BHN kinetics and provide relatively constrained [H2SO4] needed for nucleation. H2SO4 is produced from the SO2+OH→HSO3 reaction and OH radicals are produced from water vapor UV absorption. The residual [H2SO4] were measured at the end of the nucleation reactor with a chemical ionization mass spectrometer (CIMS. Wall loss factors (WLFs of H2SO4 were estimated by assuming that wall loss is diffusion limited and these calculated WLFs were in good agreement with simultaneous measurements of the initial and residual [H2SO4] with two CIMSs. The nucleation zone was estimated from numerical simulations based on the measured aerosol sizes (particle diameter, Dp and [H2SO4]. The measured BHN rates (J ranged from 0.01–220 cm−3 s−1 at the initial and residual [H2SO4] from 108−1010 cm−3, a temperature of 288 K and relative humidity (RH from 11–23%; J increased with increasing [H2SO4] and RH. J also showed a power dependence on [H2SO4] with the exponential power of 3–8. These power dependences are consistent with other laboratory studies under similar [H2SO4] and RH, but different from atmospheric field observations which showed that particle number concentrations are often linearly dependent on [H2SO4]. These results, together with a higher [H2SO4] threshold (108–109 cm−3 needed to produce the unit J measured from the laboratory studies compared to the atmospheric conditions (106–107 cm−3, imply that H2SO4/H2O BHN alone is

  2. Rapid food decomposition by H2O2-H2SO4 for determination of total mercury by flow injection cold vapor atomic absorption spectrometry.

    Science.gov (United States)

    Zenebon, Odair; Sakuma, Alice M; Dovidauskas, Sergio; Okada, Isaura A; de, MaioFrancaD; Lichtig, Jaim

    2002-01-01

    A mixture of 50% H2O2-H2SO4 (3 + 1, v/v) was used for decomposition of food in open vessels at 80 degrees C. The treatment allowed rapid total mercury determination by flow injection cold vapor atomic absorption spectrometry. Cabbage, potatoes, peanuts paste, hazelnuts paste, oats, tomatoes and their derivatives, oysters, shrimps, prawns, shellfish, marine algae, and many kinds of fish were analyzed by the proposed methodology with a limit of quantitation of 0.86 +/- 0.08 microg/L mercury in the final solution. Reference materials tested also gave excellent recovery.

  3. submitter Thermodynamics of the formation of sulfuric acid dimers in the binary (H2SO4–H2O) and ternary (H2SO4–H2O–NH3) system

    CERN Document Server

    Kürten, A; Rondo, L; Bianchi, F; Duplissy, J; Jokinen, T; Junninen, H; Sarnela, N; Schobesberger, S; Simon, M; Sipilä, M; Almeida, J; Amorim, A; Dommen, J; Donahue, N M; Dunne, E M; Flagan, R C; Franchin, A; Kirkby, J; Kupc, A; Makhmutov, V; Petäjä, T; Praplan, A P; Riccobono, F; Steiner, G; Tomé, A; Tsagkogeorgas, G; Wagner, P E; Wimmer, D; Baltensperger, U; Kulmala, M; Worsnop, D R; Curtius, J

    2015-01-01

    Sulfuric acid is an important gas influencing atmospheric new particle formation (NPF). Both the binary $(H_2SO_4–H_2O)$ system and the ternary system involving ammonia $(H_2SO_4–H_2O–NH_3)$ may be important in the free troposphere. An essential step in the nucleation of aerosol particles from gas-phase precursors is the formation of a dimer, so an understanding of the thermodynamics of dimer formation over a wide range of atmospheric conditions is essential to describe NPF. We have used the CLOUD chamber to conduct nucleation experiments for these systems at temperatures from 208 to 248 K. Neutral monomer and dimer concentrations of sulfuric acid were measured using a chemical ionization mass spectrometer (CIMS). From these measurements, dimer evaporation rates in the binary system were derived for temperatures of 208 and 223 K. We compare these results to literature data from a previous study that was conducted at higher temperatures but is in good agreement with the present study. For the ternary sys...

  4. INHIBITION EFFECT OF FLAVONOID EXTRACT OF Euphorbia Guyoniana ON THE CORROSION OF MILD STEEL IN H2SO4 MEDIUM

    Directory of Open Access Journals (Sweden)

    S. Chihi

    2009-08-01

    Full Text Available The influence of flavonoids extracts of three parts of Euphorbia Guyoniana towards the corrosion of type API 5L X52 steel in 15% H2SO4 has been evaluated by weight loss method and polarization technique. The results showed that extracts are a good inhibitors for API 5L X52 steel in this medium. The corrosion inhibition efficiency increases on increasing plant extracts concentration. The inhibition is attributed to the adsorption of the surface of the metal. Potentiodynamic polarization results revealed that the studied inhibitors behave as a mixed type.

  5. Using HABIT to Estimate the Concentration of CO2 and H2SO4 for Kuosheng Nuclear Power Plant

    OpenAIRE

    Y. Chiang; W. Y. Li; J. R. Wang; S. W. Chen; W. S. Hsu; J. H. Yang; Y. S. Tseng; C. Shih

    2017-01-01

    In this research, the HABIT code was used to estimate the concentration under the CO2 and H2SO4 storage burst conditions for Kuosheng nuclear power plant (NPP). The Final Safety Analysis Report (FSAR) and reports were used in this research. In addition, to evaluate the control room habitability for these cases, the HABIT analysis results were compared with the R.G. 1.78 failure criteria. The comparison results show that the HABIT results are below the criteria. Additionally, some sensitivity ...

  6. Temperature Effects on Stainless Steel 316L Corrosion in the Environment of Sulphuric Acid (H2SO4)

    Science.gov (United States)

    Ayu Arwati, I. G.; Herianto Majlan, Edy; Daud, Wan Ramli Wan; Shyuan, Loh Kee; Arifin, Khuzaimah Binti; Husaini, Teuku; Alfa, Sagir; Ashidiq, Fakhruddien

    2018-03-01

    In its application, metal is always in contact with its environment whether air, vapor, water, and other chemicals. During contact, chemical interactions emerge between metals and their respective environments such that the metal surface corrodes. This study aims to determine the corrosion rate of 316L stainless steel sulphuric acid environment (H2SO4) with weight loss and electrochemical methods. The corrosion rate (CR) is value of 316L stainless steel by weight loss method with sulfuric acid (H2SO4) with concentration of 0.5 M. The result obtained in conjunction with the increase of temperature the rate of erosion obtained appears to be larger, with a consecutive 3 hour the temperature of 50°C is 0.27 mg/cm2h, temperature 70°C 0.38 mg/cm2h, and temperature 90 °C 0.52 mg/cm2h. With the electrochemical method, the current value increases by using a C350 potentiostal tool. The higher the current, the longer the time the corrosion rate increases, where the current is at 90 °C with a 10-minute treatment time of 0.0014736 A. The 316L stainless steel in surface metal morphology is shown by using a Scanning Electron Microscope (SEM).

  7. Pengaruh Konsentrasi H2so4 Dan Berat Dari Bentonit Alam Teraktivasi Dan Komersil Terhadap Adsorpsi Logam Kadmium (Cd) Dan Tembaga (Cu) Dalam Larutan Standar Dalam Metode Spektrofotometri Serapan Atom

    OpenAIRE

    Ramadani, Eko

    2011-01-01

    The various concentration effect’s of H2SO4 and weight of activated bleaching earth and commercial to adsoption of cadmium metal (Cd) and copper (Cu) in standard solution using Atomic Absorption Spectrophotometric method has been studied. Bleaching earth activation process assessed various concentration of H2SO4 which is 0,4; 0,8; 1,2; 1,6; and 2,0 M. 1, 2, 3, 4, and 5 g activated bleaching earth and commercial added into cadmium standard solution (Cd) and copper (Cu) , stirred up to 6 hours,...

  8. Decapado de un acero inoxidable austenítico mediante mezclas ecológicas basadas en H2O2 - H2SO4 - iones F-

    Directory of Open Access Journals (Sweden)

    Narváez, L.

    2013-04-01

    Full Text Available This study reports the pickling of 316L stainless steel using mixtures of hydrogen peroxide (H2O2, sulphuric acid (H2SO4 and fluoride ions as hydrofluoric acid (HF, sodium fluoride (NaF and potassium fluoride (KF. The decomposition of H2O2 in the mixtures was assessed at different temperatures 25 °C to 60 °C, with ferric ion contents from 0 to 40 g/l. According to the results obtained, were established the optimal condition pickling at 20 g/l of ferric ions, 25 °C and p-toluensulphonic acid as stabilizer of H2O2. The HF pickling mixture was the only capable to remove totally the oxide layer from the 316L stainless steel after 300 s. The fluoride salts pickling mixtures only remove partially the oxide layer (20 to 40 % aprox. after 300 s. When the pickling time was increased until 1200 s, the removal percentages were around to 80 %.En este estudio se presenta el decapado del acero inoxidable austenítico 316L utilizando mezclas de peróxido de hidrógeno (H2O2/ácido sulfúrico (H2SO4/iones fluoruro; los iones fluoruro provienen del ácido fluorhídrico (HF, fluoruro de sodio (NaF y fluoruro de potasio (KF. La estabilidad del H2O2 fue valorada modificando las concentraciones del ión férrico de 0 a 40 g/l y las temperaturas de 25 °C a 60 °C en las mezclas decapantes. Se establecieron las condiciones óptimas de decapado utilizando 20 g/l de iones férrico a 25 °C empleando el ácido p-toluensulfónico como estabilizante del H2O2. La mezcla que contenía HF fue la única capaz de eliminar completamente los óxidos superficiales del acero a tiempos de 300 s. Las mezclas a base de sales fluoradas eliminaron parcialmente los óxidos (20 y 40 % aprox. en 300 s. Al incrementar el tiempo de decapado hasta 1200 s se obtuvieron porcentajes de eliminación alrededor de un 80 %.

  9. Evaluation of Resin Regeneration Using HCl and H2SO4 for the Ion Exchanger of Copper

    International Nuclear Information System (INIS)

    Prayitno; Djoko Sardjono

    2002-01-01

    The experimental investigation on the regeneration of resin using HCl and H 2 SO 4 with its varian concentration of 1; 2.5; 2; 2.5 and 3 N and the stirring time was 5; 10; 15; 20; and 25 minutes. For evaluating their effectiveness on the separation of ion copper in the waste with concentration 500 ppm. Experimentally this investigation is the first step of resin results of regeneration process usage as an alternative resin for the treatment of liquid waste containing especially copper. The experimental resulted by mixing the feed copper waste with resin after regeneration. Therefore it could be concluded that the most effective regeneration was obtained with HCl as the regeneration of concentration 2 N and the stirring time 15 minutes with the percentage of separation used of 85.1 %. (author)

  10. Electrocatalysts of platinum, cobalt and nickel prepared by mechanical alloying for the oxygen reduction reaction in H2SO4 0.5M

    International Nuclear Information System (INIS)

    Garcia C, M.A.; Fernandez V, S.M.; Vargas G, J.R.

    2007-01-01

    Metallic powders of Pt, Co and Nickel were processed by mechanical alloyed and electrocatalysts were synthesized for the oxygen reduction reaction, applicable in fuel cells. The structural and morphological characterization was carried out using X-ray Diffraction, scanning electron microscopy and transmission electron microscopy. It was found that the alloyed powders formed agglomerates that consist of crystalline particles of nano metric size. Its were obtained polarization curves by the Electrode of Rotational Disk technique in a solution of H 2 SO 4 0.5 M, used as electrolyte, to evaluate the electrocatalytic activity of mechanically alloyed powders. Tafel graphics were built to determine the kinetic parameters of each electro catalyst. The PtCoNi alloy exhibited the biggest electrocatalytic activity, with the smallest over potential for the oxygen reduction reaction. (Author)

  11. Efecto de la corrosión por h 2 so 4 en la difusividad térmica de acero api5l-x52.

    Directory of Open Access Journals (Sweden)

    Gabriel Peña-Rodríguez

    2004-01-01

    Full Text Available In this work present a study of the effect of the H2SO4 corrosion to constant pH of 1.4 in the thermal diffusivity of API5L-X52 pipeline steel. The samples were exposed by 3, 6, 9, 12 and 15 days to the corrosive solution, in an atmosphere with relative average humidity of 57.16% and temperature of 23.6°C. The thermal diffusivity measure was carried out using the photoacoustic technique in a heat transmission configuration. Our results show a decrease of the thermal diffusivity ( a with the corrosion time, presenting a behavior that is adjusted to a logistical curve of type decreasing with a saturation limit of 52% of a initial value.

  12. Corrosion inhibition of iron in 0.5 mol L-1 H2SO4 by halide ions

    Directory of Open Access Journals (Sweden)

    Jeyaprabha C.

    2006-01-01

    Full Text Available The inhibition effect of halide ions such as iodide, bromide and chloride ions on the corrosion of iron in 0.5 mol L-1 H2SO4 and the adsorption behaviour of these ions on the electrode surface have been studied by polarization and impedance methods. It has been found that the inhibition of nearly 90% has been observed for iodide ions at 2.5 10-3 mol L-1, for bromide ions at 10 10-3 mol L-1 and 80% for chloride ions at 2.5 10-3 mol L-1. The inhibition effect is increased with increase of halide ions concentration in the case of I- and Br- ions, whereas it has decreased in the case of Cl- ion at concentrations higher than 5 10-3 mol L-1. The double layer capacitance values have decreased considerably in the presence of halide ions which indicate that these anions are adsorbed on iron at the corrosion potential.

  13. Synergistic effect of halide ions on the corrosion inhibition of aluminium in H2SO4 using 2-acetylphenothiazine

    International Nuclear Information System (INIS)

    Ebenso, E.E.

    2003-01-01

    The corrosion inhibition of aluminium in H 2 SO 4 in the presence of 2-acetylphenothiazine (2APTZ) at temperature range of 30-60 deg. C was studied using the weight loss and thermometric techniques. The effect of addition of halides (KCl, KBr, KI) is also reported. The inhibition efficiency (I, %) increased with increase in concentration of 2APTZ. The addition of the halides increased the inhibition efficiency to a considerable extent. The temperature increased the corrosion rate and inhibition efficiency in the range 30-60 deg. C in the absence and presence of the inhibitor and halides. Phenomenon of chemical adsorption is proposed. Flory-Huggins adsorption isotherm equation was obeyed at all the concentrations studied. The decrease in inhibition efficiency (and surface coverage values) was found to be in the order I - >Br - >Cl - which clearly indicates that the radii and the electronegativity of halides play a significant role in the adsorption process. All the data acquired reveal that 2APTZ acts as an inhibitor in the acid environment from the two techniques used. The synergistic effect of 2APTZ and halide ions is discussed

  14. The Effects of EDTA and H2SO4 on Phyto-extraction of Pb from contaminated Soils by Radish

    Directory of Open Access Journals (Sweden)

    T. Mansouri

    2016-10-01

    Full Text Available Introduction: Soil contamination by heavy metals is one of the most important environmental concerns in many parts of the world. The remediation of soil contaminated with heavy metals is necessary to prevent the entry of these metals into the human food chain. Phyto-extraction is an effective, cheap and environmental friendly method which uses plants for cleaning contaminated soils. The plants are used for phytoremediation should have high potential for heavy metals uptake and produce enormous amount of biomass. A major problem facing phyto-extraction method is the immobility of heavy metals in soils. Chemical phyto-extraction is a method in which different acids and chelating substances are used to enhance the mobility of heavy metals in soil and their uptake by plants. The aims of this study were: (a to determine the potential of radish to extract Pb from contaminated soils and (b to assess the effects of different soil amendment (EDTA and H2SO4 to enhance plant uptake of the heavy metal and (c to study the effects of different levels of soil Pb on radish growth and Pb concentrations of above and below ground parts of this plant. Materials and Methods: Soil samples were air dried and passed through a 2 mm sieve and analysed for some physico-chemical properties and then artificially contaminated with seven levels of lead (0, 200, 400, 600, 800 and 1000 mg/kg using Pb(NO32 salt and then planted radish. During the growth period of radish and after the initiation of root growth, the plants were treated with three levels of sulfuric acid (0, 750 and 1500 mg/kg or three levels of EDTA (0, 10 and 20 mg/kg through irrigation water. At the end of growth period, the above and below ground parts of the plants were harvested, washed, dried and digested using a mixture of HNO3, HCl, and H2O2. The concentrations of Pb, N, P and K in plant extracts were measured. Statistical analysis of data was performed using MSTATC software and comparison of means was

  15. Inhibitory action of quaternary ammonium bromide on mild steel and synergistic effect with other halide ions in 0.5 M H2SO4

    Directory of Open Access Journals (Sweden)

    A. Khamis

    2014-11-01

    Full Text Available The corrosion inhibition of mild steel in 0.5 M H2SO4 solution has been investigated using electrochemical methods, X-ray diffraction (XRD and scanning electron microscope (SEM. The adsorption and inhibition action of acid corrosion of mild steel using cetyltrimethylammonium bromide (CTABr and different halides (NaCl, NaBr and NaI has shown synergetic effect. The results showed that the protection efficiency (P% has high values at considerable high concentration of CTABr. However, in the presence of the different halides, the P increases dramatically at low concentration of CTABr. Physisorption was proposed from the the values of ΔGads0. The synergism parameter (Sθ is found to be greater than unity indicating that the enhanced P% caused by the addition of the halides to the CTABr is due to a co-operative adsorption of both species. Corrosion products phases and surface morphology were studied using X-ray diffraction (XRD and scanning electron microscopy (SEM, respectively.

  16. The Cs2SO4-Ce2(SO4)3-H2SO4-H2O system at 150 and 200 deg C

    International Nuclear Information System (INIS)

    Bondar', S.A.; Belokoskov, V.I.; Trofimov, G.V.

    1982-01-01

    Solubility in the system Cs 2 SO 4 -Ce 2 (SO 4 ) 3 -H 2 SO 4 -H 2 O using the isothermal method at 150 and 200 deg C at molar ratios Cs 2 SO 4 :Ce 2 (SO 4 ) 3 =1:5 and conditions of sulfate crystallization Cs 2 SO 4 xCe 2 (SO 4 ) 3 , Ce 2 (SO 4 ) 3 x0.5H 2 SO 4 xnH 2 O (n=2-3) and Ce 2 (SO 4 ) 3 x3H 2 SO 4 are determined. Double sulfate Cs 2 SO 4 xCe 2 (SO 4 ) 3 is studied using the methods of crystallooptical, thermal, X-ray phase analyses and IR spectroscopy

  17. Laboratory measurement of the millimeter wave properties of liquid sulfuric acid (H2SO4). [study of microwave emission from Venus

    Science.gov (United States)

    Fahd, Antoine K.; Steffes, Paul G.

    1991-01-01

    The methodology and the results of laboratory measurements of the millimeter wave properties of liquid sulfuric acid are presented. Measurements conducted at 30-40 and 90-100 GHz are reported, using different concentrations of liquid H2SO4. The measured data are used to compute the expected opacity of H2SO4 condensates and their effects on the millimeter wave emission from Venus. The cloud condensate is found to have an effect on the emission from Venus. The calculated decrease in brightness temperature is well below the observed decrease in brightness temperature found by de Pater et al. (1991). It is suggested that other constituents such as gaseous H2SO4 also affect the observed variation in the brightness temperature.

  18. Tailoring of TiO2 films by H2SO4 treatment and UV irradiation to improve anticoagulant ability and endothelial cell compatibility.

    Science.gov (United States)

    Liao, Yuzhen; Li, Linhua; Chen, Jiang; Yang, Ping; Zhao, Ansha; Sun, Hong; Huang, Nan

    2017-07-01

    Surfaces with dual functions that simultaneously exhibit good anticoagulant ability and endothelial cell (EC) compatibility are desirable for blood contact materials. However, these dual functions have rarely been achieved by inorganic materials. In this study, titanium dioxide (TiO 2 ) films were treated by sulphuric acid (H 2 SO 4 ) and ultraviolet (UV) irradiation successively (TiO 2 H 2 SO 4 -UV), resulting in good anticoagulant ability and EC compatibility simultaneously. We found that UV irradiation improved the anticoagulant ability of TiO 2 films significantly while enhancing EC compatibility, though not significantly. The enhanced anticoagulant ability could be related to the oxidation of surface-adsorbed hydrocarbons and increased hydrophilicity. The H 2 SO 4 treatment improved the anticoagulant ability of TiO 2 films slightly, while UV irradiation improved the anticoagulant ability strongly. The enhanced EC compatibility could be related to the increased surface roughness and positive charges on the surface of the TiO 2 films. Furthermore, the time-dependent degradation of the enhanced EC compatibility and anticoagulant ability of TiO 2 H 2 SO 4 -UV was observed. In summary, TiO 2 H 2 SO 4 -UV expressed both excellent anticoagulant ability and good EC compatibility at the same time, which could be desirable for blood contact materials. However, the compatibility of TiO 2 H 2 SO 4 -UV with smooth muscle cells (SMCs) and macrophages was also improved. More effort is still needed to selectively improve EC compatibility on TiO 2 films for better re-endothelialization. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Vanadium Flow Battery Electrolyte Synthesis via Chemical Reduction of V2O5 in Aqueous HCl and H2SO4.

    Energy Technology Data Exchange (ETDEWEB)

    Small, Leo J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pratt, Harry [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Staiger, Chad [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Rachel Irene [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Anderson, Travis Mark [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Chalamala, Babu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Soundappan, Thiagarajan [Univ. of Washington, Seattle, WA (United States); Tiwari, Monika [Univ. of Washington, Seattle, WA (United States); Subarmanian, Venkat R. [Univ. of Washington, Seattle, WA (United States)

    2017-01-01

    We report a simple method to synthesize V 4+ (VO 2+ ) electrolytes as feedstock for all- vanadium redox flow batteries (RFB). By dissolving V 2 O 5 in aqueous HCl and H 2 SO 4 , subsequently adding glycerol as a reducing agent, we have demonstrated an inexpensive route for electrolyte synthesis to concentrations >2.5 M V 4+ (VO 2+ ). Electrochemical analysis and testing of laboratory scale RFB demonstrate improved thermal stability across a wider temperature range (-10-65 degC) for V 4+ (VO 2+ ) electrolytes in HCl compared to in H 2 SO 4 electrolytes.

  20. On the Growth of Ternary System HNO3/H2SO4/H2O Aerosol Particles in the Stratosphere

    Science.gov (United States)

    Hamill, Patrick; Tabazadeh, A.; Kinne, S.; Toon, O. B.; Turco, R. P.

    1996-01-01

    We present a study of the growth of ternary solution (nitric acid, sulfuric acid and water) droplets in the stratosphere. The growth mechanism is hetero-molecular condensation in which the particle is assumed to be in equilibrium with environmental water vapor. Model results are in reasonable agreement with the averaged extinction ratio obtained by the SAM II satellite system.

  1. Anti-Corrosion Performance of 1,3-BENZOTHIAZOLE on 410 Martensitic Stainless Steel in H2SO4

    Science.gov (United States)

    Loto, Roland Tolulope

    The corrosion inhibition effect of synthesized 1,3-benzothiazole at very low concentrations on 410 martensitic stainless steel in 3MH2SO4 solution was studied through potentiodynamic polarization and weight loss measurements. The observation showed that the organic compound performed effectively with average inhibition efficiencies of 94% and 98% at the concentrations studied from both electrochemical methods due to the inhibition action of protonated inhibitor molecules in the acid solution. The amine and aromatics functional groups of the molecules active in the corrosion inhibition reaction were exposed from Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopic analysis. Thermodynamic calculations showed cationic adsorption to be chemisorption adsorption, obeying the Langmuir adsorption isotherm. Images from optical microscopy showed an improved morphology in comparison to images from corroded stainless steel. Severe surface deterioration and macro-pits were observed in the uninhibited samples.

  2. Gaseous (DMS, MSA, SO2, H2SO4 and DMSO and particulate (sulfate and methanesulfonate sulfur species over the northeastern coast of Crete

    Directory of Open Access Journals (Sweden)

    H. Bardouki

    2003-01-01

    Full Text Available A detailed study of the levels, the temporal and diurnal variability of the main compounds involved in the biogenic sulfur cycle was carried out in Crete (Eastern Mediterranean during the Mediterranean Intensive Oxidant Study (MINOS field experiment in July-August 2001. Intensive measurements of gaseous dimethylsulfide (DMS, dimethylsulfoxide (DMSO, sulfur dioxide (SO2, sulfuric (H2SO4 and methanesulfonic acids (MSA and particulate sulfate (SO42- and methanesulfonate (MS- have been performed during the campaign. Dimethylsulfide (DMS levels ranged from 2.9 to 136 pmol·mol-1 (mean value of 21.7 pmol·mol-1 and showed a clear diurnal variation with daytime maximum. During nighttime DMS levels fall close or below the detection limit of 2 pmol·mol-1. Concurrent measurements of OH and NO3 radicals during the campaign indicate that NO3 levels can explain most of the observed diurnal variation of DMS. Dimethylsulfoxide (DMSO ranged between 0.02 and 10.1 pmol·mol-1 (mean value of 1.7 pmol·mol-1 and presents a diurnal variation similar to that of DMS. SO2 levels ranged from 220 to 2970 pmol·mol-1 (mean value of 1030 pmol·mol-1, while nss-SO42- and MS- ranged from 330 to 7100 pmol·mol-1, (mean value of 1440 pmol·mol-1 and 1.1 to 37.5 pmol·mol-1 (mean value of 11.5 pmol·mol-1 respectively. Of particular interest are the measurements of gaseous MSA and H2SO4. MSA ranged from below the detection limit (3x104 to 3.7x107 molecules cm-3, whereas H2SO4 ranged between 1x105 and 9.0x107 molecules cm-3. The measured H2SO4 maxima are among the highest reported in literature and can be attributed to high insolation, absence of precipitation and increased SO2 levels in the area. From the concurrent SO2, OH, and H2SO4 measurements a sticking coefficient of 0.52±0.28 was calculated for H2SO4. From the concurrent MSA, OH, and DMS measurements the yield of gaseous MSA from the OH-initiated oxidation of DMS was calculated to range between 0.1-0.4%. This low MSA

  3. Experimental study of cluster formation in binary mixture of H2O and H2SO4 vapors in the presence of an ionizing radiation source

    Science.gov (United States)

    Singh, J. J.; Smith, A. C.; Yue, G. K.

    1980-01-01

    Molecular clusters formed in pure nitrogen containing H2O and H2SO4 vapors and exposed to a 3 mCi Ni63 beta source were studied in the mass range 50 to 780 amu using a quadrupole mass spectrometer. Measurements were made under several combinations of relative humidity and relative acidity ranging from 0.7 to 7.5 percent and 0.00047 to 0.06333 percent, respectively. The number of H2SO4 molecules in the clusters observed ranged from 1 to 7 whereas the number of H2O molecules ranged from 1 to 16. The experimental cluster spectra differ considerably from those calculated using the classical nucleation theory. First order calculations using modified surface tension values and including the effects of multipole moments of the nucleating molecules indicate that these effects may be enough to explain the difference between the measured and the calculated spectra.

  4. Hemicelluloses negatively affect lignocellulose crystallinity for high biomass digestibility under NaOH and H2SO4 pretreatments in Miscanthus

    Directory of Open Access Journals (Sweden)

    Xu Ning

    2012-08-01

    Full Text Available Abstract Background Lignocellulose is the most abundant biomass on earth. However, biomass recalcitrance has become a major factor affecting biofuel production. Although cellulose crystallinity significantly influences biomass saccharification, little is known about the impact of three major wall polymers on cellulose crystallization. In this study, we selected six typical pairs of Miscanthus samples that presented different cell wall compositions, and then compared their cellulose crystallinity and biomass digestibility after various chemical pretreatments. Results A Miscanthus sample with a high hemicelluloses level was determined to have a relatively low cellulose crystallinity index (CrI and enhanced biomass digestibility at similar rates after pretreatments of NaOH and H2SO4 with three concentrations. By contrast, a Miscanthus sample with a high cellulose or lignin level showed increased CrI and low biomass saccharification, particularly after H2SO4 pretreatment. Correlation analysis revealed that the cellulose CrI negatively affected biomass digestion. Increased hemicelluloses level by 25% or decreased cellulose and lignin contents by 31% and 37% were also found to result in increased hexose yields by 1.3-times to 2.2-times released from enzymatic hydrolysis after NaOH or H2SO4 pretreatments. The findings indicated that hemicelluloses were the dominant and positive factor, whereas cellulose and lignin had synergistic and negative effects on biomass digestibility. Conclusions Using six pairs of Miscanthus samples with different cell wall compositions, hemicelluloses were revealed to be the dominant factor that positively determined biomass digestibility after pretreatments with NaOH or H2SO4 by negatively affecting cellulose crystallinity. The results suggested potential approaches to the genetic modifications of bioenergy crops.

  5. Pengolahan Internal Air Boiler Dengan Penambahan Asam Sulfat (H2SO4) 98% dan Kaustik Soda (NaOH) Di PTPN III Pabrik Kelapa Sawit Rambutan Tebing Tinggi

    OpenAIRE

    Simanjuntak, Depi Fitri

    2010-01-01

    Have been do observation to treatment of water domestic boiler with additional material of chemistry that is: H2SO4 98 % in tank cation and NaOH in tank anion. From result of observation, so geted, pH value, Total Dissolved Solid (TDS), Phenolphtalein Alkalinity, Methyl Alkalinity, Total Alkalinity, Sulfite, Chloride, Total Hardness, Hardness, has appropriate with prerequirement water of boiler wich used in PTPN III RAMBUTAN TEBING TINGGI. 072409006

  6. Modeling impacts of NH3 on uptake of H2SO4 by charged nucleating nanoparticles in the Earth's atmosphere

    International Nuclear Information System (INIS)

    Nadykto, A. B.; Nazarenko, K. M.; Markov, P. N.; Yu, F.

    2016-01-01

    The understanding of the role of ammonia, a well-known stabilizer of binary sulfuric acid-water clusters, in the gas-to-nanoparticle conversion in the Earth atmosphere is critically important for the assessment of aerosol radiative forcing associated with the climate changes. The sulfuric acid H 2 SO 4 is present in the atmosphere in the form of the gas-phase hydrates (H 2 SO 4 )(H 2 O) n , whose interaction with NH 3 leads to the formation of more stable bisulfate clusters (NH 3 )(H 2 SO 4 )(H 2 O) n . Although the impact of NH 3 on the thermochemical stability of binary clusters nucleating homogeneously has been studied in some detail in the past, the effect of ammonia on other microphysical properties relevant to nucleation remains insufficiently well understood. In the present study, the effect of ammonia on the electrical dipole moment controlling the nucleation of airborne ions via the dipole-charge interaction has been investigated using the Density Functional Theory (DFT), ab initio MP2 and model chemistry G3 methods. The presence of ammonia in (H 2 SO 4 )(H 2 O) n is found to lead to very large enhancement in the dipole moment, which exceeds 2.0-2.5 Debyes (∼60-80%), 3.7-5.0 Debyes (∼90-180%), 1.4-4.5 Debyes (∼50-150%) and 2.1-5.5 Debyes (∼60-700%) for n = 0, n = 1, n = 2 and n = 3, respectively. The implications of this include the significantly increased uptake of the sulfuric acid, the key atmospheric nucleation precursor, by airborne ions and neutrals (due to dipole-dipole interaction), enhanced nucleation rates and the elevated production of ultrafine particles, which cause adverse health impacts.

  7. Proses Treatment Dengan Menggunakan NaOCl Dan H2SO4 Untuk Mempercepat Pembuatan Bioetanol Dari Limbah Rumput Laut Eucheuma Cottonii

    Directory of Open Access Journals (Sweden)

    I Nyoman Winjaya Putra

    2012-11-01

    Full Text Available The fermentation process of the waste of Eucheuma cottonii seaweed to become bioethanol can beaccelerated by providing special treatment, such as delignification process using NaOCl and immersion byusing a mixture of H2SO4 for different variations. The fermentation process is also be done by using the yeast ofSaccharomyces cerevisiae with a variety of mixtures, to determine the rate of bioethanol fermentation.In this study NaOCl has been used with variation of 0.25%, 0.50% and 0.75%. H2SO4 is used with aconcentration of 0.5% and the variations of Saccharomyces cerevisiae yeast with a ratio of 1: 0.0015; 1: 0.003;1: 0.0045; 1: 0.006 and 1: 0.0075 for every kilogram of waste Eucheuma Cottonii and yeast, and withfermentation time of 3, 6 and 9 days. As a comparison is the same treatment, but without the use of H2SO4.Based on the research, the following results obtained. The highest rate of bioethanol fermentation is4.4% per day and the highest levels of ethanol produced is 14.0%. This is achieved for where each kilogram ofwaste of Eucheuma cottonii is delignificated with a concentration of 0.5% NaOCl followed by a treatment inphysics, with the variations of yeast 1: 0.006 and with a time of fermentation for 3 days.

  8. [BMim][HSO4]-H2SO4二组分物系密度的测定及相关热力学性质的研究%Density and thermodynamic properties of binary[BMim][HSO4]-H2SO4 system

    Institute of Scientific and Technical Information of China (English)

    张帅; 张涛; 唐盛伟

    2016-01-01

    在常压和283.15~313.15 K的温度范围内,测定了离子液体1-丁基-3-甲基咪唑硫酸氢盐([BMim][HSO4])与H2SO4二组分物系在全浓度范围内的密度,由密度数据计算了不同温度和浓度下混合物的超额摩尔体积(VE)和各组分的偏摩尔体积,基于半经验Zhang方程和NMSRK状态方程建立了二组分物系密度的预测模型。实验结果表明,两种模型的计算值与实验值具有较高的符合度,其平均绝对误差均不超过0.30%;在全浓度范围内二组分物系的VE均为正值,当xH2SO4=0.60时,物系的VE达到最大,最大值为2.46280 cm3/mol(313.15 K);二组分物系中[BMim][HSO4]的偏摩尔体积随xH2SO4的增大而增大, H2SO4的偏摩尔体积随xH2SO4的增大而减小。%Under the conditions of ambient pressure and 283.15-313.15 K,the density of binary [BMim][HSO4]-H2SO4 systems with the molar fraction of H2SO4 of 0-1 was measured. Based on the obtained density data,the excess molar volume of the systems and the partial molar volumes of the two components at different temperature were calculated. The models for predicting the density of the binary systems were established by means of the semi-empirical Zhang model and NMSRK equation of state separately. It was showed that,the two models predict the density of the binary systems well with an average deviation of less than 0.30%. The excess molar volumes of all the measured binary systems were greater than zero and the maximum value of 2.462 80 cm3/mol was obtained under the conditions of molar fracton of H2SO4 0.60 and 313.15 K. In the binary systems,with increasing the molar fraction of H2SO4, the partial molar volume of[BMim][HSO4] increased while the partial molar volume of H2SO4 decreased.

  9. Phase formation in the systems ZrO2-H2SO4-Na2SO4 (NaCl)-H2O

    International Nuclear Information System (INIS)

    Sozinova, Yu.P.; Motov, D.L.; Rys'kina, M.P.

    1988-01-01

    Formation of solid phases in the systems ZrO 2 - H 2 SO 4 - Na 2 SO 4 (NaCl) - H 2 O at 25 and 75 deg C is studied. Three basic Na 2 Zr(OH) 2 (SO 4 ) 2 x (0.2 - 0.4)H 2 O, NaZrOH(SO 4 ) 2 x H 2 O, NaZrO 0.5 (OH) 2 SO 4 x 2H 2 O and three normal sodium sulfatozirconates Na 2 Zr(SO 4 ) 3 x 3H 2 O, Na 4 Zr(SO 4 ) 4 x 3H 2 O, Na 6 Zr(SO 4 ) 5 x 4H 2 O have been isolated, their solubility and crystal optical properties are determined

  10. GaAs micromachining in the 1 H2SO4:1 H2O2:8 H2O system. From anisotropy to simulation

    Science.gov (United States)

    Tellier, C. R.

    2011-02-01

    The bulk micromachining on (010), (110) and (111)A GaAs substrates in the 1 H2SO4:1 H2O2:8 H2O system is investigated. Focus is placed on anisotropy of 3D etching shapes with a special emphasis on convex and concave undercuts which are of prime importance in the wet micromachining of mechanical structures. Etched structures exhibit curved contours and more and less rounded sidewalls showing that the anisotropy is of type 2. This anisotropy can be conveniently described by a kinematic and tensorial model. Hence, a database composed of dissolution constants is further determined from experiments. A self-elaborated simulator which works with the proposed database is used to derive theoretical 3D shapes. Simulated shapes agree well with observed shapes of microstructures. The successful simulations open up two important applications for MEMS: CAD of mask patterns and meshing of simulated shapes for FEM simulation tools.

  11. Study of ZrO2-H2SO4-(NH4)2SO4(NH4Cl)-H2O systems

    International Nuclear Information System (INIS)

    Motov, D.L.; Sozinova, Yu.P.; Rys'kina, M.P.

    1988-01-01

    Regions of formation, composition and solubility of ammonium sulfatozirconates (ASZ) in ZrO 2 -H 2 SO 4 -(NH 4 ) 2 SO 4 (NH 4 Cl)-H 2 O systems at 25 and 75 deg C are studied by the isothermal method. Five ASZ: (NH 4 ) 2 Zr(OH) 2 (SO 4 ) 2 , NH 4 ZrOH(SO 4 ) 2 xH 2 O, NH 4 ZrO 0.5 (OH) 2 SO 4 x1.5H 2 O, (NH 4 ) 2 Zr(SO 4 ) 3 x2H 2 O, (NH 4 ) 4 Zr(SO 4 ) 4 x4H 2 O are detected, their properties are investigated. Main sulfates are new compounds never described ealier

  12. The effects of H2SO4 and (NH42SO4 treatments on the chemistry of soil drainage water and pine seedlings in forest soil microcosms

    Directory of Open Access Journals (Sweden)

    M. I. Stutter

    2004-01-01

    Full Text Available An experiment comparing effects of sulphuric acid and reduced N deposition on soil water quality and on chemical and physical growth indicators for forest ecosystems is described. Six H2SO4 and (NH42SO4 treatment loads, from 0 – 44 and 0 – 25 kmolc ha-1 yr-1, respectively, were applied to outdoor microcosms of Pinus sylvestris seedlings in 3 acid to intermediate upland soils (calc-silicate, quartzite and granite for 2 years. Different soil types responded similarly to H2SO4 loads, resulting in decreased leachate pH, but differently to reduced N inputs. In microcosms of calc-silicate soil, nitrification of NH4 resulted in lower pH and higher cation leaching than in acid treatments. By contrast, in quartzite and granite soils, (NH42SO4 promoted direct cation leaching, although leachate pH increased. The results highlighted the importance of soil composition on the nature of the cations leached, the SO4 adsorption capacities and microbial N transformations. Greater seedling growth on calc-silicate soils under both treatment types was related to sustained nutrient availability. Reductions in foliar P and Mg with higher N treatments were observed for seedlings in the calc-silicate soil. There were few treatment effects on quartzite and granite microcosm tree seedlings since P limitation precluded seedling growth responses to treatments. Hence, any benefits of N deposition to seedlings on quartzite and granite soils appeared limited by availability of co-nutrients, exacerbated by rapid depletion of soil exchangeable base cations. Keywords: acidification, manipulation, nitrogen, ammonium, deposition, soil, drainage, pine, microcosms, forest

  13. Influence of tannin content in Terminalia catappa leaves extracts resulted from maceration extraction on decreasing corrosion rate for mild steel in 1M H2SO4

    Science.gov (United States)

    Pramudita, M.; Sukirno; Nasikin, M.

    2018-04-01

    The ability of natural compounds as corrosion inhibitors is necessary to obtain safe corrosion inhibitors for the environment. The tannin compounds derived from plant extract has the ability to decrease the corrosion rate. The purpose of this research is to find the ability of tannin compounds in Terminalia catappa leaves extracts to decrease corrosion rate on mild steel. Terminalia catappa leaves that have been mashed in ethanol solvent extraction using maceration with the variable time 2.4 and 6 days. Mild steel that has been on the sandpaper and cleaned then soak into the 1 M H2SO4. Terminalia catappa leaves extract concentration used is 0, 250, 500, 500, 750, 1000 ppm, the immersion time is 3.6 and 9 hours. Calculating of corrosion rate is used the weight loss method, the analysis of the tannin concentration using GC-MS. The results indicate that highest tannin content equal to 7.23% in 6 days maceration time. The result showed that the corrosion rate was reduced in the presence of tannin content in Terminalia catappa leaves extract.

  14. Exploring the atmospheric chemistry of O2SO3- and assessing the maximum turnover number of ion-catalysed H2SO4 formation

    DEFF Research Database (Denmark)

    Bork, Nicolai Christian; Kurtén, T.; Vehkamäki, H.

    2013-01-01

    molecule, but reaction (b) is in general much more probable. Although we are unable to assess the overall importance of this cycle in the real atmosphere due to the unknown influence of CO2 and NOx, we roughly estimate that ion-induced catalysis may contribute with several percent of H2SO4 levels......It has recently been demonstrated that the O2SO3- ion forms in the atmosphere as a natural consequence of ionizing radiation. Here, we present a density functional theory-based study of the reactions of O2SO3- with O-3. The most important reactions are (a) oxidation to O3SO3- and (b) cluster...... the two major sinks for O2SO3- is assessed, thereby providing a measure of the maximum turnover number of ion-catalysed SO2 oxidation, i.e. how many SO2 can be oxidized per free electron. The rate ratio between reactions (a) and (b) is significantly altered by the presence or absence of a single water...

  15. Exploring the atmospheric chemistry of O2SO3− and assessing the maximum turnover number of ion-catalysed H2SO4 formation

    Directory of Open Access Journals (Sweden)

    N. Bork

    2013-04-01

    Full Text Available It has recently been demonstrated that the O2SO3− ion forms in the atmosphere as a natural consequence of ionizing radiation. Here, we present a density functional theory-based study of the reactions of O2SO3− with O3. The most important reactions are (a oxidation to O2SO3− and (b cluster decomposition into SO3, O2 and O3−. The former reaction is highly exothermic, and the nascent O2SO3− will rapidly decompose into SO4− and O2. If the origin of O2SO3− is SO2 oxidation by O3−, the latter reaction closes a catalytic cycle wherein SO2 is oxidized to SO3. The relative rate between the two major sinks for O2SO3− is assessed, thereby providing a measure of the maximum turnover number of ion-catalysed SO2 oxidation, i.e. how many SO2 can be oxidized per free electron. The rate ratio between reactions (a and (b is significantly altered by the presence or absence of a single water molecule, but reaction (b is in general much more probable. Although we are unable to assess the overall importance of this cycle in the real atmosphere due to the unknown influence of CO2 and NOx, we roughly estimate that ion-induced catalysis may contribute with several percent of H2SO4 levels in typical CO2-free and low NOx reaction chambers, e.g. the CLOUD chamber at CERN.

  16. Flexible all-solid-state supercapacitors based on graphene/carbon black nanoparticle film electrodes and cross-linked poly(vinyl alcohol)-H2SO4 porous gel electrolytes

    Science.gov (United States)

    Fei, Haojie; Yang, Chongyang; Bao, Hua; Wang, Gengchao

    2014-11-01

    Flexible all-solid-state supercapacitors (SCs) are fabricated using graphene/carbon black nanoparticle (GCB) film electrodes and cross-linked poly(vinyl alcohol)-H2SO4 porous gel electrolytes (gPVAP-H2SO4). The GCB composite films, with carbon black (CB) nanoparticles uniformly distributed in the graphene nanosheets, greatly improve the active surface areas and ion transportation of pristine graphene film. The porous structure of as-prepared gPVAP-H2SO4 membrane improves the equilibrium swelling ratio in electrolyte and provides interconnected ion transport channels. The chemical crosslinking solves the fluidity problem of PVA-H2SO4 gel electrolyte at high temperature. As-fabricated GCB//gPVAP(20)-H2SO4//GCB flexible SC displays an increased specific capacitance (144.5 F g-1 at 0.5 A g-1) and a higher specific capacitance retention (67.9% from 0.2 to 4 A g-1). More importantly, the flexible SC possesses good electrochemical performance at high temperature (capacitance retention of 78.3% after 1000 cycles at 70 °C).

  17. The roles of Al2Cu and of dendritic refinement on surface corrosion resistance of hypoeutectic Al-Cu alloys immersed in H2SO4

    International Nuclear Information System (INIS)

    Osorio, Wislei R.; Spinelli, Jose E.; Freire, Celia M.A.; Cardona, Margarita B.; Garcia, Amauri

    2007-01-01

    Al-Cu alloys castings can exhibit different corrosion responses at different locations due to copper content and to the resulting differences on microstructural features and on Al 2 Cu fractions. The aim of this study was to investigate the influence of Al 2 Cu intermetallic particles associated to the dendritic arm spacings on the general corrosion resistance of three different hypoeutectic Al-Cu alloys samples in sulfuric acid solution. The cast samples were produced using a non-consumable tungsten electrode furnace with a water-cooled copper hearth under argon atmosphere. The typical microstructural pattern was examined by using electronic microscopy techniques. In order to evaluate the surface corrosion behavior of such Al-Cu alloys, corrosion tests were performed in a 0.5 M sulfuric acid solution at 25 deg. C by using an electrochemical impedance spectroscopy (EIS) technique and potentiodynamic polarization curves. An equivalent circuit was also used to provide quantitative support for the discussions and understanding of the corrosion behavior. It was found that Al 2 Cu has a less noble corrosion potential than that of the Al-rich phase. Despite that, dendrite fineness has proved to be more influent on corrosion resistance than the increase on alloy copper content with the consequent increase on Al 2 Cu fraction

  18. ATR-SEIRAS study of CO adsorption and oxidation on Rh modified Au(111-25 nm) film electrodes in 0.1 M H2SO4

    International Nuclear Information System (INIS)

    Xu, Qinqin; Berná, Antonio; Pobelov, Ilya V.; Rodes, Antonio; Feliu, Juan M.; Wandlowski, Thomas; Kuzume, Akiyoshi

    2015-01-01

    Rh modified Au(111-25 nm) electrodes, prepared by electron beam evaporation and galvanostatic deposition, were employed to study adsorption and electro-oxidation of CO on Rh in 0.1 M sulfuric acid solution by in situ attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). The results of ATR-SEIRAS experiments were compared with those obtained by infrared reflection absorption spectroscopy on three low-index Rh single crystal surfaces. The Rh film deposited on Au(111-25 nm) electrode consists of 3D clusters forming a highly stepped [n(111) × (111)]-like surface with narrow (111) terraces. When CO was dosed at the hydrogen adsorption potential region, CO adsorbed in both atop (CO L ) and bridge (CO B ) configurations, as well as coadsorbed water species, were detected on the Rh film electrode. A partial interconversion of spectroscopic bands due to the CO displacement from bridge to atop sites was found during the anodic potential scan, revealing that there is a potential-dependent preference of CO adsorption sites on Rh surfaces. Our data indicate that CO oxidation on Rh electrode surface in acidic media involves coadsorbed water and follows the nucleation and growth model of a Langmuir-Hinshelwood type reaction

  19. Rhodium based clusters for oxygen reduction and hydrogen oxidation in 0.5 M H2SO4, tolerant to methanol and carbon monoxide, respectively

    Energy Technology Data Exchange (ETDEWEB)

    Uribe-Godinez, J.; Jimenez-Sandoval, O.; Borja-Arco, E.; Altamirano-Gutierrez, A. [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, Queritaro (Mexico); Castellanos, R.H. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-Queretaro, Queretaro (Mexico)

    2008-07-01

    Rhodium (Rh6(CO)16) and novel Rh-based clusters were prepared using thermolysis techniques under different conditions in N2 and H2 reaction media, as well as in n-nonane, o-xylene, 1,2-dichlorobenzene and dimethylsulfoxide. The clusters were used as novel electrocatalysts for oxygen reduction reaction (ORR) in the absence and presence of 1.0 and 2.0 M methanol solutions. The catalysts were also used for hydrogen oxidation reaction (HOR) with pure hydrogen (H2) and in the presence of carbon monoxide (CO). Rotating disk electrode measurements were used to analyze the materials. The study showed that the electrocatalyst support ratio plays a significant role in the electrochemical behaviour of the materials. Rh6(CO)16 and Rh2(1,2-DCB) presented the best electrocatalytic behaviour for ORR and HOR in the absence and presence of methanol and CO. The study demonstrated that the rhodium-based materials are capable of performing ORR and HOR while being tolerant of both methanol and CO. 3 refs., 3 figs.

  20. Standard test method for determining plutonium by controlled-potential coulometry in H2SO4 at a platinum working electrode

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1990-01-01

    1.1 This test method covers the determination of milligram quantities of plutonium in unirradiated uranium-plutonium mixed oxide having a U/Pu ratio range of 0.1 to 10. This test method is also applicable to plutonium metal, plutonium oxide, uranium-plutonium mixed carbide, various plutonium compounds including fluoride and chloride salts, and plutonium solutions. 1.2 The recommended amount of plutonium for each aliquant in the coulometric analysis is 5 to 10 mg. Precision worsens for lower amounts of plutonium, and elapsed time of electrolysis becomes impractical for higher amounts of plutonium. 1.3 The values stated in SI units are to be regarded as standard. No other units are to be regarded as standard. 1.4 This standard does not purport to address all of the safety concens, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precaution...

  1. The reactions of SO3 with HO2 radical and H2O...HO2 radical complex. Theoretical study on the atmospheric formation of HSO5 and H2SO4.

    Science.gov (United States)

    Gonzalez, Javier; Torrent-Sucarrat, Miquel; Anglada, Josep M

    2010-03-07

    The influence of a single water molecule on the gas-phase reactivity of the HO(2) radical has been investigated by studying the reactions of SO(3) with the HO(2) radical and with the H(2)O...HO(2) radical complex. The naked reaction leads to the formation of the HSO(5) radical, with a computed binding energy of 13.81 kcal mol(-1). The reaction with the H(2)O...HO(2) radical complex can give two different products, namely (a) HSO(5) + H(2)O, which has a binding energy that is computed to be 4.76 kcal mol(-1) more stable than the SO(3) + H(2)O...HO(2) reactants (Delta(E + ZPE) at 0K) and an estimated branching ratio of about 34% at 298K and (b) sulfuric acid and the hydroperoxyl radical, which is computed to be 10.51 kcal mol(-1) below the energy of the reactants (Delta(E + ZPE) at 0K), with an estimated branching ratio of about 66% at 298K. The fact that one of the products is H(2)SO(4) may have relevance in the chemistry of the atmosphere. Interestingly, the water molecule acts as a catalyst, [as it occurs in (a)] or as a reactant [as it occurs in (b)]. For a sake of completeness we have also calculated the anharmonic vibrational frequencies for HO(2), HSO(5), the HSO(5)...H(2)O hydrogen bonded complex, H(2)SO(4), and two H(2)SO(4)...H(2)O complexes, in order to help with the possible experimental identification of some of these species.

  2. Studies on the relationship between Pitzer's equation and medium effect: the system of HCl + H2SO4 in {0.06455C2H5OH + 0.93545H2O}

    International Nuclear Information System (INIS)

    Lu Xingmei; Xu Weiguo; Chang Xiaohong; Lu Dianzhen; Yang Jiazhen

    2004-01-01

    The second ionization constant of sulfuric acid in mixed solvent, K 2 , was determined by e.m.f. of cell without liquid junction: (Pt,H 2 (101.325 kPa) vertical bar HCl(m 1 ),H 2 SO 4 (m 2 ),{ethanol(x=0.06455)+water(x=0.93545)} vertical bar AgCl-Ag))over the temperatures (278.15 to 318.15) K, where x is mole fraction. Combining Owen's definition of medium effect with Pitzer's equations, the values of combination parameters: (λ nHS +λ nCl -λ nS )+(3/2)m n (μ nnHS +μ nnCl -μ nnS ),(1/2)(ξ nHHS +ξ nHCl -ξ nHS ), that represent the interactions between ions and ethanol were obtained at 298.15 K.

  3. Phyllanthus muellerianus and C6H15NO3 synergistic effects on 0.5 M H2SO4-immersed steel-reinforced concrete: Implication for clean corrosion-protection of wind energy structures in industrial environment

    Science.gov (United States)

    Okeniyi, Joshua Olusegun; Omotosho, Olugbenga Adeshola; Popoola, Abimbola Patricia Idowu; Loto, Cleophas Akintoye

    2016-07-01

    This paper investigates Phyllanthus muellerianus leaf-extract and C6H15NO3 (triethanolamine: TEA) synergistic effects on reinforcing-steel corrosion-inhibition and the compressive-strength of steel-reinforced concrete immersed in 0.5 M H2SO4. This is to assess suitability of the synergistic admixture usage for wind-energy steel-reinforced concrete structures designed for industrial environments. Steel-reinforced concrete specimens were admixed with individual and synergistic designs of Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures and immersed in the 0.5 M H2SO4. Electrochemical monitoring of corrosion potential, as per ASTM C876-91 R99, and corrosion current were obtained and statistically analysed, as per ASTM G16-95 R04, for modelling noise resistance. Post-immersion compressive-strength testing then followed, as per ASTM C39/C39M-03, for detailing the admixture effect on load-bearing strength of the steel-reinforced concrete specimens. Results showed that while individual Phyllanthus muellerianus leaf-extract concentrations exhibited better inhibition-efficiency performance than C6H15NO3, synergistic additions of C6H15NO3 to Phyllanthus muellerianus leaf-extract improved steel-rebar corrosion-inhibition. Thus, 6 g Phyllanthus muellerianus + 2 g C6H15NO3 synergistically improved inhibition-efficiency to η = 84.17%, from η = 55.28% by the optimal chemical or from η = 74.72% by the optimal plant-extract admixtures. The study also established that improved compressive strength of steel-reinforced concrete with acceptable inhibition of the steel-rebar corrosion could be attained through optimal combination of the Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures.

  4. Influence of reaction products of K-getter fuel additives on commercial vanadia-based SCR catalysts Part II. Simultaneous addition of KCl, Ca(OH)(2), H3PO4 and H2SO4 in a hot flue gas at a SCR pilot-scale setup

    DEFF Research Database (Denmark)

    Castellino, Francesco; Jensen, Anker Degn; Johnsson, Jan Erik

    2009-01-01

    A commercial V2O5-WO3-TiO2 corrugated-type SCR monolith has been exposed for 1000 h in a pilot-scale setup to a flue gas doped with KCl, Ca(OH)(2), H3PO4 and H2SO4 by spraying a water solution of the components into the hot flue gas. The mixture composition has been adjusted in order to have P...... surface and did not proceed at the fast rates known for KCl. This fact indicates that binding K in P-K-Ca compounds is an effective way to reduce the negative influence of alkali metals on the lifetime of the vanadia-based SCR catalysts. On the other hand, P-deposition was favoured by the formation...

  5. Development of a new corona discharge based ion source for high resolution time-of-flight chemical ionization mass spectrometer to measure gaseous H2SO4 and aerosol sulfate

    Science.gov (United States)

    Zheng, Jun; Yang, Dongsen; Ma, Yan; Chen, Mindong; Cheng, Jin; Li, Shizheng; Wang, Ming

    2015-10-01

    A new corona discharge (CD) based ion source was developed for a commercial high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS) (Aerodyne Research Inc.) to measure both gaseous sulfuric acid (H2SO4) and aerosol sulfate after thermal desorption. Nitrate core ions (NO3-) were used as reagent ions and were generated by a negative discharge in zero air followed by addition of excess nitrogen dioxide (NO2) to convert primary ions and hydroxyl radicals (OH) into NO3- ions and nitric acid (HNO3). The CD-HRToF-CIMS showed no detectable interference from hundreds parts per billion by volume (ppbv) of sulfur dioxide (SO2). Unlike the atmospheric pressure ionization (API) ToF-CIMS, the CD ion source was integrated onto the ion-molecule reaction (IMR) chamber and which made it possible to measure aerosol sulfate by coupling to a filter inlet for gases and aerosols (FIGAERO). Moreover, compared with a quadrupole-based mass spectrometer, the desired HSO4- signal was detected by its exact mass of m/z 96.960, which was well resolved from the potential interferences of HCO3-ṡ(H2O)2 (m/z 97.014) and O-ṡH2OṡHNO3 (m/z 97.002). In this work, using laboratory-generated standards the CD-HRToF-CIMS was demonstrated to be able to detect as low as 3.1 × 105 molecules cm-3 gaseous H2SO4 and 0.5 μg m-3 ammonium sulfate based on 10-s integration time and two times of the baseline noise. The CD ion source had the advantages of low cost and a simple but robust structure. Since the system was non-radioactive and did not require corrosive HNO3 gas, it can be readily field deployed. The CD-HRToF-CIMS can be a powerful tool for both field and laboratory studies of aerosol formation mechanism and the chemical processes that were critical to understand the evolution of aerosols in the atmosphere.

  6. SEMICONDUCTOR TECHNOLOGY: Wet etching characteristics of a HfSiON high-k dielectric in HF-based solutions

    Science.gov (United States)

    Yongliang, Li; Qiuxia, Xu

    2010-03-01

    The wet etching properties of a HfSiON high-k dielectric in HF-based solutions are investigated. HF-based solutions are the most promising wet chemistries for the removal of HfSiON, and etch selectivity of HF-based solutions can be improved by the addition of an acid and/or an alcohol to the HF solution. Due to densification during annealing, the etch rate of HfSiON annealed at 900 °C for 30 s is significantly reduced compared with as-deposited HfSiON in HF-based solutions. After the HfSiON film has been completely removed by HF-based solutions, it is not possible to etch the interfacial layer and the etched surface does not have a hydrophobic nature, since N diffuses to the interface layer or Si substrate formation of Si-N bonds that dissolves very slowly in HF-based solutions. Existing Si-N bonds at the interface between the new high-k dielectric deposit and the Si substrate may degrade the carrier mobility due to Coulomb scattering. In addition, we show that N2 plasma treatment before wet etching is not very effective in increasing the wet etch rate for a thin HfSiON film in our case.

  7. Wet etching characteristics of a HfSiON high-k dielectric in HF-based solutions

    International Nuclear Information System (INIS)

    Li Yongliang; Xu Qiuxia

    2010-01-01

    The wet etching properties of a HfSiON high-k dielectric in HF-based solutions are investigated. HF-based solutions are the most promising wet chemistries for the removal of HfSiON, and etch selectivity of HF-based solutions can be improved by the addition of an acid and/or an alcohol to the HF solution. Due to densification during annealing, the etch rate of HfSiON annealed at 900 0 C for 30 s is significantly reduced compared with as-deposited HfSiON in HF-based solutions. After the HfSiON film has been completely removed by HF-based solutions, it is not possible to etch the interfacial layer and the etched surface does not have a hydrophobic nature, since N diffuses to the interface layer or Si substrate formation of Si-N bonds that dissolves very slowly in HF-based solutions. Existing Si-N bonds at the interface between the new high-k dielectric deposit and the Si substrate may degrade the carrier mobility due to Coulomb scattering. In addition, we show that N 2 plasma treatment before wet etching is not very effective in increasing the wet etch rate for a thin HfSiON film in our case. (semiconductor technology)

  8. High-temperature x-ray diffraction study of HfTiO4-HfO2 solid solutions

    International Nuclear Information System (INIS)

    Carpenter, D.A.

    1975-01-01

    High-temperature x-ray diffraction techniques were used to determine the axial thermal expansion curves of HfTiO 4 -HfO 2 solid solutions as a function of composition. Data show increasing anisotropy with increasing HfO 2 content. An orthorhombic-to-monoclinic phase transformation was detected near room temperature for compositions near the high HfO 2 end of the orthorhombic phase field and for compositions within the two-phase region (HfTiO 4 solid solution plus HfO 2 solid solution). An orthorhombic-to-cubic phase transformation is indicated by data from oxygen-deficient materials at greater than 1873 0 K. (U.S.)

  9. Theoretical predictions of hydrolysis and complex formation of group-4 elements Zr, Hf and Rf in HF and HCl solutions

    International Nuclear Information System (INIS)

    Pershina, V.; Trubert, D.; Le Naour, C.; Kratz, J.V.

    2002-01-01

    Fully relativistic molecular density-functional calculations of the electronic structures of hydrated, hydrolyzed and fluoride/chloride complexes have been performed for group-4 elements Zr, Hf, and element 104, Rf. Using the electronic density distribution data, relative values of the free energy change for hydrolysis and complex formation reactions were defined. The results show the following trend for the first hydrolysis step of the cationic species: Zr>Hf>Rf in agreement with experiments. For the complex formation in HF solutions, the trend to a decrease from Zr to Hf is continued with Rf, provided no hydrolysis takes place. At pH>0, further fluorination of hydrolyzed species or fluoro-complexes has an inversed trend in the group Rf≥Zr>Hf, with the difference between the elements being very small. For the complex formation in HCl solutions, the trend is continued with Rf, so that Zr>Hf>Rf independently of pH. A decisive energetic factor in hydrolysis or complex formation processes proved to be a predominant electrostatic metal-ligand interaction. Trends in the K d (distribution coefficient) values for the group-4 elements are expected to follow those of the complex formation

  10. On the stabilization of NbV-solutions by ZrIV and HfIV

    International Nuclear Information System (INIS)

    Soerensen, E.; Bjerre, A.B.

    1987-11-01

    Niobium cannot be separated from zirconium or hafnium when these elements occur together in solution with common anions such as Cl- and SO 4 --. This is ascribed to the copolymerisation of Nb v and the hydrolyzed ionic species of Zr IV v and Hf IV by which the colloidal particles are masked as Zr- and Hf-compounds. In HCl the particles are positively charged as opposed to when they are in sulphate solution where the Zr- and Hf- sulphate complexes confer a negative charge. The two cases are considered separately. (author)

  11. Extraction behavior of Nb and Ta in HF solutions with tributyl phosphate

    International Nuclear Information System (INIS)

    Murakami, M.; Tsuto, S.; Ooe, K.; Goto, S.; Kudo, H.; Haba, H.; Kanaya, J.

    2013-01-01

    Extraction behavior of carrier-free Nb and Ta with tributyl phosphate (TBP) from HF solutions was studied by a batch method. Tantalum is extracted well to an organic phase, while Nb is left in an aqueous phase at 0.053-1.0 M HF concentrations. The similar extraction trends of Nb and Ta are shown in the solid phase extraction using a TBP resin. The extraction equilibria in the solid phase extraction are attained within ∼10 s. (author)

  12. Anion exchange behavior of Ti, Zr, Hf, Nb and Ta as homologues of Rf and Db in mixed HF-acetone solutions

    International Nuclear Information System (INIS)

    Aksenov, N.V.; Bozhikov, G.A.; Starodub, G.Ya.; Dmitriev, S.N.; Filosofov, D.V.; Jon Sun Jin; Radchenko, V.I.; Lebedev, N.A.; Novgorodov, A.F.

    2009-01-01

    We studied in detail the sorption behavior of Ti, Zr, Hf, Nb and Ta on AG 1 anion exchange resin in HF-acetone mixed solutions as a function of organic cosolvent and acid concentrations. Anion exchange behavior was found to be strongly acetone concentration dependent. The distribution coefficients of Ti, Zr, Hf and Nb increased and those of Ta decreased with increasing content of acetone in HF solutions. With increasing HF concentration, anion exchange equilibrium analysis indicated the formation of fluoride complexes of group-4 elements with charge -3 and Ta with charge -2. For Nb the slope of -2 increased up to -5. Optimal conditions for separation of the elements using AIX chromatography were found. Group-4 elements formed MF 7 3- (M = Ti, Zr, Hf) complexes whose sorption decreased Ti > Hf > Zr in reverse order of complex stability. This fact is of particular interest for studying ion exchange behavior of Rf compared to Ti. The advantages of studying chemical properties of Rf and Db in aqueous HF solutions mixed with organic solvents are briefly discussed

  13. Solution Structure of Enterocin HF, an Antilisterial Bacteriocin Produced by Enterococcus faecium M3K31.

    Science.gov (United States)

    Arbulu, Sara; Lohans, Christopher T; van Belkum, Marco J; Cintas, Luis M; Herranz, Carmen; Vederas, John C; Hernández, Pablo E

    2015-12-16

    The solution structure of enterocin HF (EntHF), a class IIa bacteriocin of 43 amino acids produced by Enterococcus faecium M3K31, was evaluated by CD and NMR spectroscopy. Purified EntHF was unstructured in water, but CD analysis supports that EntHF adopts an α-helical conformation when exposed to increasing concentrations of trifluoroethanol. Furthermore, NMR spectroscopy indicates that this bacteriocin adopts an antiparallel β-sheet structure in the N-terminal region (residues 1-17), followed by a well-defined central α-helix (residues 19-30) and a more disordered C-terminal end (residues 31-43). EntHF could be structurally organized into three flexible regions that might act in a coordinated manner. This is in agreement with the absence of long-range nuclear Overhauser effect signals between the β-sheet domain and the C-terminal end of the bacteriocin. The 3D structure recorded for EntHF fits emerging facts regarding target recognition and mode of action of class IIa bacteriocins.

  14. Ideal solution behaviour of glassy Cu–Ti, Zr, Hf alloys and properties of amorphous copper

    International Nuclear Information System (INIS)

    Ristić, R.; Cooper, J.R.; Zadro, K.; Pajić, D.; Ivkov, J.; Babić, E.

    2015-01-01

    Highlights: • Ideal solution behaviour (ISB) is established in all Cu–Ti, Zr, Hf glassy alloys. • ISB enables reliable estimates for various properties of amorphous Cu. • ISB also impacts glass forming ability in these and probably other similar alloys. - Abstract: A comprehensive study of selected properties of amorphous (a) Cu–TE alloys (TE = Ti, Zr and Hf) has been performed. Data for average atomic volumes of a-Cu–Hf, Ti alloys combined with literature data show that ideal solution behaviour (Vegard’s law) extends over the whole glass forming range (GFR) in all a-Cu–TE alloys. This enables one to obtain an insight into some properties and probable atomic arrangements for both, a-TEs (Ristić et al., 2010) and a-Cu by extrapolation of the data for alloys. Indeed the atomic volumes and other properties studied for all a-Cu–TE alloys extrapolate to the same values for a-Cu. Depending on the property, these values are either close to those of crystalline (c) Cu, or are close to those for liquid (L) Cu. In particular, the electronic transport properties of a-Cu seem close to those of L-Cu, whereas the static properties, such as the density of states, and Young’s modulus, converge to those of c-Cu. The possible impact of these results on our understanding of a-Cu–TE alloys, including glass forming ability, is discussed

  15. Mechanism of plutonium metal dissolution in HNO3-HF-N2H4 solution

    International Nuclear Information System (INIS)

    Karraker, D.G.

    1985-01-01

    An oxidation-reduction balance of the products of the dissolution of plutonium metal and alloys in HNO 3 -HF-N 2 H 4 solution shows that the major reactions during dissolution are the reduction of nitrate to NH 3 , N 2 and N 2 O by the metal, and the oxidation of H free radicals to NH 3 by N 2 H 4 . Reactions between HNO 3 and N 2 H 4 produce varying amounts of HN 3 . The reaction rate is greater for delta-Pu than alpha-Pu, and is increased by higher concentrations of HF and HNO 3 . The low yield of reduced nitrogen species indicates that nitrate is reduced on the metal surface without producing a significant concentration of species that react with N 2 H 4 . It is conjectured that intermediate Pu valences and electron transfer within the metal are involved. 7 refs., 3 tabs

  16. Surface characterisation of ethylene-propylene-diene rubber upon exposure to aqueous acidic solution

    DEFF Research Database (Denmark)

    Mitra, S.; Ghanbari-Siahkali, Afshin; Kingshott, P.

    2006-01-01

    but significantly different with respect to molar mass and the presence of long chain branching. Both rubbers contained 5-ethylidene-2-norbomene (ENB) as diene. Solution cast films of pure EPDM samples were exposed in two different acidic solutions, viz. chromosulphuric (Cr (VI)/H2SO4) and sulphuric acid (H2SO4....... Furthermore, 20% Cr (VI)/H2SO4 also attacked the allylic carbon-hydrogen (C-H) bonds of ENB resulting in more oxygenated species on the surface compared to 20% H2SO4 under identical conditions. Cr (VI) in the 20% Cr (VI)/H2SO4 was found to play an important role in alteration of surface chemistry. Studies...

  17. Dispersion capacitive de l'interface H2SO4/Pt Capacitive dispersion ...

    African Journals Online (AJOL)

    Administrateur

    Département de Physique, Faculté des Sciences Exactes. Université des .... d'un comportement idéal de la capacité. Au vu .... Figure 2 : Photographie de la cellule Pt/0,5 MH2SO4 (fabriquée par Verre-Lab Constantine) plongée dans un bain.

  18. Macroscopic assembled, ultrastrong and H2SO4-resistant fibres of polymer-grafted graphene oxide

    Science.gov (United States)

    Zhao, Xiaoli; Xu, Zhen; Zheng, Bingna; Gao, Chao

    2013-11-01

    Nacre realizes strength and toughness through hierarchical designs with primary ``brick and mortar'' structures of alternative arrangement of nanoplatelets and biomacromolecules, and these have inspired the fabrication of nanocomposites for decades. However, to simultaneously solve the three critical problems of phase separation, low interfacial strength and random orientation of nanofillers for nanocomposites is a great challenge yet. Here we demonstrate that polymer-grafted graphene oxide sheets are exceptional building blocks for nanocomposites. Their liquid crystalline dispersions can be wet-spun into continuous fibres. Because of well-ordering and efficient load transfer, the composites show remarkable tensile strength (500 MPa), three to four times higher than nacre. The uniform layered microstructures and strong interlayer interactions also endow the fibres good resistance to chemicals including 98% sulfuric acid. We studied the enhancing effect of nanofillers with fraction in a whole range (0-100%), and proposed an equation to depict the relationship.

  19. Synthesis of H2SO4 doped polyaniline film by potentiometric method

    Indian Academy of Sciences (India)

    Unknown

    probe method permits measurements of the resis- tivity in the samples having wide variety of shapes, including the resistivity of small volume within bigger semiconductor. The present work deals with the conductivity measurements.

  20. Polarographic, spectrophotometric and coulometric studies of MoO=4 in H2SO4

    International Nuclear Information System (INIS)

    Tokoro, R.; Bertotti, M.

    1990-01-01

    This study characterizes the polarographic process of Mo O sup(=) sub(4) in H sub(2)SO sub(4) medium, determining which species is responsible by catalytic cycle. Spectrophotometric and coulometric studies are also described. (author)

  1. Enlarging the fission fragment tracks in glass detectors by etching in weak solutions of HF - a safe etchant

    International Nuclear Information System (INIS)

    Singh, V.P.; Sharma, A.P.

    1982-01-01

    The effect of etchant concentration and temperature on track revelation properties of soda glass detectors has been studied. Etch rate ratio, maximum observable diameter and the energy resolution of the fission fragment tracks of 252 Cf in glasses are increased when the samples are etched in 1.25 vol% HF as compared to higher concentrations of HF and other etching solutions. The critical angle of etching is found to decrease with decrease in etchant concentration. The activation energies for bulk etching and track etching have also been estimated. Better results were obtained by using lower etching temperatures. (author)

  2. HF effect on dissociation kinetics of plutonium and neptunium complexes with 1,2-diaminocyclohexanetetraacetic acid in nitric acid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Nikitina, S.A.; Stepanov, A.V.

    1982-01-01

    Dissociation kinetics of Pusup((4)) and Np sup((4)) complexes with DCTA were investigated in HNO/sub 3/ solutions in the presence of HF and arsenazo 3. It was found that HF or NaF produced a differentiating effect on the reactivity of the complexes at (HNO/sub 3/)=1-6 mol/l as well as inhibiting effect at (HNO/sub 3/)=0.01 mol/l. Conditions of the differential kinetic analysis of plutonium and neptunium in the mixture and differential spectrophotometric analysis of uranium (6) during the camouflage of neptunium (4) and plutonium (4) were determined.

  3. HF effect on dissociation kinetics of plutonium and neptunium complexes with 1,2-diaminocyclohexanetetraacetic acid in nitric acid solutions

    International Nuclear Information System (INIS)

    Nikitina, S.A.; Stepanov, A.V.

    1982-01-01

    Dissociation kinetics of Pusup((4)) and Np sup((4)) complexes with DCTA were investigated in HNO 3 solutions in the presence of HF and arsenazo 3. It was found that HF or NaF produced a differentiating effect on the reactivity of the complexes at [HNO 3 ]=1-6 mol/l as well as inhibiting effect at [HNO 3 ]=0.01 mol/l. Conditions of the differential kinetic analysis of plutonium and neptunium in the mixture and differential spectrophotometric analysis of uranium (6) during the camouflage of neptunium (4) and plutonium (4) were determined

  4. First results on the sorption behaviour of Rutherfordium from HCl/HF containing aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, D.; Nitsche, H. [Technische Univ. Dresden (Germany); Taut, S. [Forschungszentrum Rossendorf e.V. (FZR), Dresden (Germany); Jost, D.T.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Yakushev, A.B.; Buklanov, G.V.; Domanov, V.P.; Lien Din Thi [Joint Inst. for Nuclear Research, Dubna (Russian Federation); Kubica, B.; Misiak, R.; Szeglowski, Z. [NINP Cracow (Poland)

    1997-09-01

    Rutherfordium shows strong sorption on the cation exchanger DOWEX 50x8 at a concentration of 0.1 M HCl/10{sup -2} M HF. This shows that Rf behaves under these conditions differently from Hf and Zr and more like Th under these conditions. (author) 1 fig., 5 refs.

  5. Bunsen Reaction using a HIx Solution (HI-I2-H2O with Countercurrent Flow for Sulfur-Iodine Hydrogen Production Process

    Directory of Open Access Journals (Sweden)

    Kim Hyo-Sub

    2016-01-01

    Full Text Available In the sulfur-iodine hydrogen production process, the Bunsen reaction is a crucial section because of the linkage with the H2SO4 and HI decomposition sections. The HIx solution (HI-I2-H2O mixture was fed to the Bunsen reaction section as a reactant from the HI decomposition section. In this study, the Bunsen reaction using the HIx solution with countercurrent flow was performed. The production rate of HIx phase solution increased while that of H2SO4 phase solution was maintained constant when increasing the flow rate of HIx solution. As the SO2 flow rate increased, the production rates of H2SO4 and HIx phase solutions increased. The amount of resultant H2SO4 phase was very lower than that of resultant HIx phase under the conditions examined in this study.

  6. New Ablation-Resistant Material Candidate for Hypersonic Applications: Synthesis, Composition, and Oxidation Resistance of HfIr3-Based Solid Solution.

    Science.gov (United States)

    Lozanov, Victor V; Baklanova, Natalya I; Bulina, Natalia V; Titov, Anatoly T

    2018-04-18

    The peculiarities of the solid-state interaction in the HfC-Ir system have been studied within the 1000-1600 °C temperature range using a set of modern analytical techniques. It was stated that the interaction of HfC with iridium becomes noticeable at temperatures as low as 1000-1100 °C and results in the formation of HfIr 3 -based substitutional solid solution. The homogeneity range of the HfIr 3± x phase was evaluated and refined as HfIr 2.43 -HfIr 3.36 . The durability of the HfIr 3 -based system under extreme environmental conditions was studied. It was shown that the HfIr 3 -based material displays excellent ablation resistance under extreme environmental conditions. The benefits of the new designed material result from its relative oxygen impermeability and special microstructure similar to superalloys. The results obtained in this work allow us to consider HfIr 3 as a very promising candidate for extreme applications.

  7. Characterization of stain etched p-type silicon in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Mogoda, A.S., E-mail: awad_mogoda@hotmail.com [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt); Ahmad, Y.H.; Badawy, W.A. [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt)

    2011-04-15

    Research highlights: {yields} Stain etching of p-Si in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4} was investigated. {yields} The electrical conductivity of the etched Si surfaces was measured using impedance technique. {yields} Scanning electron microscope and energy disperse X-ray were used to analyze the etched surfaces. {yields} Etching in aqueous HF solution containing HNO{sub 3} led to formation of a porous silicon layer. {yields} The formation of the porous silicon layer in HF/KMnO{sub 4} was accompanied by deposition of K{sub 2}SiF{sub 6} on the pores surfaces. - Abstract: Stain etching of p-type silicon in hydrofluoric acid solutions containing nitric acid or potassium permanganate as an oxidizing agent has been examined. The effects of etching time, oxidizing agent and HF concentrations on the electrochemical behavior of etched silicon surfaces have been investigated by electrochemical impedance spectroscopy (EIS). An electrical equivalent circuit was used for fitting the impedance data. The morphology and the chemical composition of the etched Si surface were studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques, respectively. A porous silicon layer was formed on Si etched in HF solutions containing HNO{sub 3}, while etching in HF solutions containing KMnO{sub 4} led to the formation of a porous layer and simultaneous deposition of K{sub 2}SiF{sub 6} inside the pores. The thickness of K{sub 2}SiF{sub 6} layer increases with increasing the KMnO{sub 4} concentration and decreases as the concentration of HF increases.

  8. Thermodynamic mixing properties of the UO{sub 2}–HfO{sub 2} solid solution: Density functional theory and Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Ke, E-mail: keyuan@umich.edu [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Ewing, Rodney C. [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Becker, Udo [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2015-03-15

    HfO{sub 2} is a neutron absorber and has been mechanically mixed with UO{sub 2} in nuclear fuel in order to control the core power distribution. During nuclear fission, the temperature at the center of the fuel pellet can reach above 1300 K, where hafnium may substitute uranium and form the binary solid solution of UO{sub 2}–HfO{sub 2}. UO{sub 2} adopts the cubic fluorite structure, but HfO{sub 2} can occur in monoclinic, tetragonal, and cubic structures. The distribution of Hf and U ions in the UO{sub 2}–HfO{sub 2} binary and its atomic structure influence the thermal conductivity and melting point of the fuel. However, experimental data on the UO{sub 2}–HfO{sub 2} binary are limited. Therefore, the enthalpies of mixing of the UO{sub 2}–HfO{sub 2} binary with three different structures were calculated in this study using density functional theory and subsequent Monte Carlo simulations. The free energy of mixing was obtained from thermodynamic integration of the enthalpy of mixing over temperature. From the ΔG of mixing, a phase diagram of the binary was obtained. The calculated UO{sub 2}–HfO{sub 2} binary forms extensive solid solution across the entire compositional range, but there are a variety of possible exsolution phenomena associated with the different HfO{sub 2} polymorphs. As the structure of the HfO{sub 2} end member adopts lower symmetry and becomes less similar to cubic UO{sub 2}, the miscibility gap of the phase diagram expands, accompanied by an increase in cell volume by 7–10% as the structure transforms from cubic to monoclinic. Close to the UO{sub 2} end member, which is relevant to the nuclear fuel, the isometric uranium-rich solid solutions exsolve as the fuel cools, and there is a tendency to form the monoclinic hafnium-rich phase in the matrix of the isometric, uranium-rich solid solution phase.

  9. Electrical behaviour of fully solution processed HfO2 (MOS) in presence of different light illumination

    Science.gov (United States)

    Mondal, Sandip

    2018-04-01

    This experiment demonstrates the electrical behaviors of fully solution processed HfO2(MOS) in presence of different optical illumination. The capacitance voltage measurement was performed at frequency of 100 kHz with a DC gate sweep voltage of ±5V (with additional AC voltage of 100mV) in presence of deep UV (wavelength of 365nm with power of 25W) as well as white light (20W). It is found that there is a large shift in flatband voltage of 120mV due presence of white light during the CV measurement. However there is negligible change in flatband voltage (30mV) has been observed due to illumination of deep UV light.

  10. Solution chemistry of element 105. Pt. III. Hydrolysis and complex formation of Nb, Ta, Db and Pa in HF and HBr solutions

    International Nuclear Information System (INIS)

    Pershina, V.; Bastug, T.

    1999-01-01

    Calculations of the electronic structure of MF 6 - and MBr 6 - complexes of Nb, Ta, Pa and element 105, Db, formed in HF and HBr solutions have been performed using the Dirac-Slater Discrete Variational method. On the basis of results of these calculations, relative values of the free energy change of reactions of complex formation have been determined. The order of the complex formation for both acids is shown to be Pa >> Nb > Db > Ta. Such a sequence is defined by a predominant electrostatic energy of the metal-ligand interaction. The hydrolysis of compounds, as a reverse process, proved to change as Ta > Db > Nb >> Pa. Using the theory of metal extraction by anion exchange, the following trend in the extraction of the anionic species from both the HF and HBr aqueous solutions has been predicted: Pa >> Nb ≥ Db > Ta. The strength of the ML 6 - complexes is shown to decrease from MF 6 , to MCl 6 and further to MBr 6 - which is reflected by shifting the complex formation process to the area of higher acid concentrations. (orig.)

  11. Low-temperature fabrication of an HfO2 passivation layer for amorphous indium-gallium-zinc oxide thin film transistors using a solution process.

    Science.gov (United States)

    Hong, Seonghwan; Park, Sung Pyo; Kim, Yeong-Gyu; Kang, Byung Ha; Na, Jae Won; Kim, Hyun Jae

    2017-11-24

    We report low-temperature solution processing of hafnium oxide (HfO 2 ) passivation layers for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). At 150 °C, the hafnium chloride (HfCl 4 ) precursor readily hydrolyzed in deionized (DI) water and transformed into an HfO 2 film. The fabricated HfO 2 passivation layer prevented any interaction between the back surface of an a-IGZO TFT and ambient gas. Moreover, diffused Hf 4+ in the back-channel layer of the a-IGZO TFT reduced the oxygen vacancy, which is the origin of the electrical instability in a-IGZO TFTs. Consequently, the a-IGZO TFT with the HfO 2 passivation layer exhibited improved stability, showing a decrease in the threshold voltage shift from 4.83 to 1.68 V under a positive bias stress test conducted over 10,000 s.

  12. Determination of total fluoride in HF/HNO3/H2SiF6 etch solutions by new potentiometric titration methods.

    Science.gov (United States)

    Weinreich, Wenke; Acker, Jörg; Gräber, Iris

    2007-03-30

    In the photovoltaic industry the etching of silicon in HF/HNO(3) solutions is a decisive process for cleaning wafer surfaces or to produce certain surface morphologies like polishing or texturization. With regard to cost efficiency, a maximal utilisation of etch baths in combination with highest quality and accuracy is strived. To provide an etch bath control realised by a replenishment with concentrated acids the main constituents of these HF/HNO(3) etch solutions including the reaction product H(2)SiF(6) have to be analysed. Two new methods for the determination of the total fluoride content in an acidic etch solution based on the precipitation titration with La(NO(3))(3) are presented within this paper. The first method bases on the proper choice of the reaction conditions, since free fluoride ions have to be liberated from HF and H(2)SiF(6) at the same time to be detected by a fluoride ion-selective electrode (F-ISE). Therefore, the sample is adjusted to a pH of 8 for total cleavage of the SiF(6)(2-) anion and titrated in absence of buffers. In a second method, the titration with La(NO(3))(3) is followed by a change of the pH-value using a HF resistant glass-electrode. Both methods provide consistent values, whereas the analysis is fast and accurate, and thus, applicable for industrial process control.

  13. Dilute H2SO4-catalyzed hydrothermal pretreatment to enhance enzymatic digestibility of Jatropha curcas fruit hull for ethanol fermentation

    NARCIS (Netherlands)

    Marasabessy, Ahmad; Kootstra, Maarten; Sanders, Johan P.M.; Weusthuis, Ruud A.

    2012-01-01

    Dilute sulfuric acid pretreatment of the Jatropha curcas fruit hull at high temperatures (140°C to 180°C) performed in a 110-mL stainless steel reactor was investigated to enhance the enzymatic digestibility of its lignocellulosic components. Carbohydrates accounted for 43% of the dry matter of

  14. Hydrogen degradation of the 26H2MF alloy steel in H2SO4 and hydrocarbon environments

    International Nuclear Information System (INIS)

    Zielinski, A.; Swieczko-Zurek, B.; Michaliak, P.

    2004-01-01

    The Polish 26H2M alloy steel has been subjected to different heat treatment resulting in different microstructure and fracture appearance. The slow strain rate tests have been made on smooth round specimens in diluted sulphuric acid, boiler fuel and used mineral machine oil. The 26H2MF steel has become relatively immune in neutral boiler fuel and mineral oil and been heavily suffered from hydrogen degradation in acidic environment. The results demonstrate that the 26H2MF steel is highly susceptible to hydrogen degradation but in absence of stress raisers the increased hydrogen absorption in hydrocarbons can cause only small loss of its plasticity. (author) >>>

  15. Study of phosphorous based resins for the uptake of plutonium from H2SO4 based analytical waste

    International Nuclear Information System (INIS)

    Seshadri, H.; Mohandas, Jaya; Srinivasan, S.; Kumar, T.; Rajan, S.K.

    2006-01-01

    This study indicates that phosphorous based resins can be conveniently employed for the uptake of plutonium from analytical wastes even in strong acid media and also in the presence of diverse ions like silver and chromium. It is also evident that phosphorous based resins have proved to be efficient even in sulphuric acid medium

  16. Sorption behaviour of W, Hf, Lu, U, and Th on ion exchangers from HCl/H2O2 solutions. Model experiments for chemical studies of seaborgium (Sg)

    International Nuclear Information System (INIS)

    Schumann, D.; Andrassy, M.; Nitsche, H.; Misiak, R.; Schaedel, M.; Bruechle, W.; Schausten, B.; Kratz, J.V.

    1997-08-01

    In model experiments with W, Hf, Th, and U radionuclides, a chemical system was developed for the separation of seaborgium from element 104 and heavy actinides, i.e., cation exchange on DOWEX 50 x 8 from solutions containing 0.1-1.0 M HCl and 0.5-2.0 vol.% H 2 O 2 . The system should be suitable for fast on-line experiments if seaborgium exibits a non-uranium-like behaviour. Adding hydrogen peroxide to mixed HCl/HF solutions suppresses the partial sorption of W and, presumably seaborgium, on the cation exchanger. This way, the elution volume can be minimized. Prospects for anion exchange separations of group 6 from 4 elements are also briefly discussed. (orig.)

  17. HF laser

    International Nuclear Information System (INIS)

    Suzuki, Kazuya; Iwasaki, Matae

    1977-01-01

    A review is made of the research and development of HF chemical laser and its related work. Many gaseous compounds are used as laser media successfully; reaction kinetics and technological problems are described. The hybrid chemical laser of HF-CO 2 system and the topics related to the isotope separation are also included. (auth.)

  18. An effective approach for restraining electrochemical corrosion of polycrystalline silicon caused by an HF-based solution and its application for mass production of MEMS devices

    International Nuclear Information System (INIS)

    Liu, Yunfei; Xie, Jing; Zhao, Hui; Luo, Wei; Yang, Jinling; An, Ji; Yang, Fuhua

    2012-01-01

    This paper presents a novel method to effectively protect the structural material polycrystalline silicon (polysilicon) from electrochemical corrosion, which often occurs when the MEMS device is released in HF-based solutions, especially when the device contains a noble metal. This corrosion seriously degrades the electrical and mechanical performance as well as the reliability of MEMS devices. In this method, a photoresist (PR) is employed to cover the noble metal, which is electrically coupled with the underlying polysilicon layer. This PR cover can effectually prevent an HF-based solution from diffusing through and arriving at the surface of the noble metal, thus cutting off the electrical current of the electrochemical corrosion reaction. The polysilicon is well protected for longer than 80 min in 49% concentrated HF solutions by a 3 µm-thick AZ 6130 PR film. This fabrication process is simple, reliable and suitable for mass production of high-end micromechanical disk resonators. Benefiting from the technology breakthrough mentioned above, a novel low-cost microfabrication method for disk resonators with high performance has been developed, and the VHF polysilicon disk resonators with resonance frequencies around 282 MHz and Q values larger than 2000 at atmosphere have been produced at wafer level. (paper)

  19. Characteristic of the Pressurized Continuous Bunsen Reaction using HIx Solution

    Directory of Open Access Journals (Sweden)

    Kim Jong-Seok

    2016-01-01

    Full Text Available The Sulfur-Iodine thermochemical hydrogen production process (SI process consists of the Bunsen reaction section, the H2SO4 decomposition section and the HI decomposition section. The HIx solution (HI-I2-H2O could be recycled to Bunsen reaction section from the HI decomposition section in the operation of the integrated SI process. The phase separation characteristic of the Bunsen reaction using the HIx solution was similar to that of SO2-I2-H2O system. However, the amount of produced H2SO4 phase was too small. To solve this problem, the study was carried out by the pressurized continuous Bunsen reaction. Bunsen reactions were performed at variation of feed rate of SO2/O2 gas in 3 bar of atmosphere. Also, it was performed to check the effects of the residence time in the reservoir on the characteristics of Bunsen products. As the results, the concentration of H2SO4 and HI in Bunsen products was increased with increasing the amounts of SO2. When the residence time in the reservoir increased, the concentration of H2SO4 and HI in HIx phase was decreased by reverse Bunsen reaction.

  20. Effective extraction of radioactive cesium from various pollutants with a detergent solution including Mg2+ and K+

    International Nuclear Information System (INIS)

    Noguchi, Yuki; Kida, Toshiyuki; Kato, Eiichi; Akashi, Mitsuru; Shimizu, Kikuo

    2015-01-01

    Radioactive cesium (Cs) is extracted effectively from various polluted samples such as soil, silt, and burned ash by washing with a detergent solution comprised of KCl, MgCl 2 , and hydroxyethyl cellulose in a 5% H 2 SO 4 aqueous solution. Repeatedly washing extracts more than 65% of the radioactive Cs. (author)

  1. Fabrications of Polyaniline Films by Pulse Electrodeposition in Acidic Solutions with Different Anions and Their Thermoelectric Performances

    Science.gov (United States)

    Yang, Weifang; Xu, Han; Li, Yuanyuan; Wang, Wei

    2017-08-01

    Polymerization of aniline was prepared by the pulse potentiostatic method in H3PO4, HClO4 and H2SO4 acidic solutions. The morphologies and thermoelectric performances were analyzed by scanning electron microscopy, Seebeck coefficient ( S) and resistivity ( R) measurements. The results show that flake polyaniline (PANI) films can be obtained in H3PO4 and HClO4 acidic solutions, and porous PANI films with nanofiber-overlapped structures can be prepared in H2SO4 solution under the same pulse parameters. PANI films prepared in the three solutions are all p-type thermoelectric materials. PANI films polymerized in H2SO4 solution possess the highest S (30.2 μV K-1) and lowest R (1.6 × 10-3 Ω m) compared with those prepared in H3PO4 and HClO4 solutions, indicating that nanofiber-overlapped structures formed in H2SO4 solution contribute better thermoelectric performance. In addition, the effects of pulse parameters (anodic potential φ a, anodic pulse duration t a and cathodic pulse duration t c) on the surface morphologies and thermoelectric performances of PANI films were systematically investigated.

  2. Velocities and mechanisms of AISI 304 steel corrosion in heated acid solutions

    International Nuclear Information System (INIS)

    Silva, B.M.; Guedes, C.D.

    1984-01-01

    The corrosion resistance of stainless steel on H 2 SO 4 at temperature higher than 60 0 C is studied. The weight loss technique and the analysis of the different components in solution are used. A proposition is made about the reason for the loss of resistance to corrosion of the stainless steel at this high temperature. (C.L.B.) [pt

  3. MoS2 Nanocube structures as catalysts for electrochemical H2 evolution from acidic aqueous solutions

    NARCIS (Netherlands)

    Maijenburg, A.W.; Regis, M.; Hattori, A.N.; Tanaka, H.; Choi, K.-S.; ten Elshof, Johan E.

    2014-01-01

    Core–shell PMMA–Au nanocube structures made by a combination of nanoimprint lithography and sidewall deposition were used as template for electrodeposition of MoS2, Ni, and Pt. Linear sweep voltammetry experiments obtained in an aqueous solution containing 0.29 M H2SO4 (pH 0.24) showed that the

  4. Role of WC additive on reaction, solid-solution and densification in HfB2–SiC ceramics

    DEFF Research Database (Denmark)

    Hu, Dong-Li; Zheng, Qiang; Gu, Hui

    2014-01-01

    A comparative study of phase components and compositions was performed for the pressureless sintered HfB2–SiC–WC composites by various analytical methods. The relative decrease of HfB2 phase leads to a new reaction of HfO2 removal by WC to create B2O3. By using SiC instead of Si3N4 as milling med...

  5. Epitaxial YBa2Cu3O7-x nanocomposite films and coated conductors from BaMO3 (M = Zr, Hf) colloidal solutions

    Science.gov (United States)

    Obradors, X.; Puig, T.; Li, Z.; Pop, C.; Mundet, B.; Chamorro, N.; Vallés, F.; Coll, M.; Ricart, S.; Vallejo, B.; Pino, F.; Palau, A.; Gázquez, J.; Ros, J.; Usoskin, A.

    2018-04-01

    Superconducting nanocomposites are the best material choice to address the performance required in power applications and magnets working under high magnetic fields. However, it is still challenging to sort out how to achieve the highest superconducting performance using attractive and competitive manufacturing processes. Colloidal solutions have been recently developed as a novel and very promising low cost route to manufacture nanocomposite coated conductors. Well dispersed and stabilized preformance nanoparticle solutions are first prepared with high concentrations and then mixed with the YBa2Cu3O7 metalorganic precursor solutions to generate colloidal solutions to grow the nanocomposite films. Here we demonstrate, for the first time, that non-reactive BaZrO3 and BaHfO3 perovskite preformed nanoparticles are suitable for growing high quality thin and thick films, and coated conductors with a homogeneous distribution and controlled particle size using this fabrication method. Additionally, we extend the nanoparticle content of the nanocomposites up to 20%-25% mol without any degradation of the superconducting properties. Thick nanocomposite films, up to 0.8 μm, have been prepared with a single deposition of low-fluorine solutions using an ink jet printing dispenser and we demonstrate that the preformed nanoparticles display only a very limited coarsening during the growth process and so high critical current densities J c (B) under high magnetic fields. These films show the highest critical currents achieved so far based on the colloidal solution approach, I c = 220 A/cm-w at 77 K and self-field, and they still have a high potential for further increase in the film thickness. Finally, we also show that nanocomposite YBa2Cu3O7-BaZrO3 coated conductors based on an alternating beam assisted deposited YSZ buffer layer on stainless steel metallic substrates can be developed based on these novel colloidal solutions. Non-reactive preformed oxide perovskite

  6. One-step synthesis of lightly doped porous silicon nanowires in HF/AgNO3/H2O2 solution at room temperature

    International Nuclear Information System (INIS)

    Bai, Fan; Li, Meicheng; Song, Dandan; Yu, Hang; Jiang, Bing; Li, Yingfeng

    2012-01-01

    One-step synthesis of lightly doped porous silicon nanowire arrays was achieved by etching the silicon wafer in HF/AgNO 3 /H 2 O 2 solution at room temperature. The lightly doped porous silicon nanowires (pNWs) have circular nanopores on the sidewall, which can emit strong green fluorescence. The surface morphologies of these nanowires could be controlled by simply adjusting the concentration of H 2 O 2 , which influences the distribution of silver nanoparticles (Ag NPs) along the nanowire axis. A mechanism based on Ag NPs-induced lateral etching of nanowires was proposed to explain the formation of pNWs. The controllable and widely applicable synthesis of pNWs will open their potential application to nanoscale photoluminescence devices. - Graphical abstract: The one-step synthesis of porous silicon nanowire arrays is achieved by chemical etching of the lightly doped p-type Si (100) wafer at room temperature. These nanowires exhibit strong green photoluminescence. SEM, TEM, HRTEM and photoluminescence images of pNWs. The scale bars of SEM, TEM HRTEM and photoluminescence are 10 μm, 20 nm, 10 nm, and 1 μm, respectively. Highlights: ► Simple one-step synthesis of lightly doped porous silicon nanowire arrays is achieved at RT. ► Etching process and mechanism are illustrated with etching model from a novel standpoint. ► As-prepared porous silicon nanowire emits strong green fluorescence, proving unique property.

  7. Characterization of lignocellulosic biomass thermal degradation and physiochemical structure: Effects of demineralization by diverse acid solutions

    International Nuclear Information System (INIS)

    Asadieraghi, Masoud; Wan Daud, Wan Mohd Ashri

    2014-01-01

    Highlights: • HF showed interesting results on EFB (empty fruit bunches) and PMF (palm mesocarp fibre) deashing. • HCl indicated maximum ash removal from PKS (palm kernel shell). • Significant pyrolysis reactions took place at ∼250 °C to ∼400 °C. • Inorganics played a considerable catalytic role during the biomasses pyrolysis. • Acid pretreatment introduced some impacts on the biomasses structure. - Abstract: To eliminate the negative impacts of inorganic constituents during biomass thermochemical processes, leaching method by different diluted acid solutions was chosen. The different palm oil biomass samples (palm kernel shell (PKS), empty fruit bunches (EFB) and palm mesocarp fiber (PMF)) were pretreated by various diluted acid solutions (H 2 SO 4 , HClO 4 , HF, HNO 3 , HCl). Acids with the highest degrees of demineralization were selected to investigate the dematerialization impacts on the biomass thermal characteristics and physiochemical structure. Thermogravimetric analysis coupled with mass spectroscopy (TGA-MS) and Fourier transform infrared spectroscopy (TGA-FTIR) were employed to examine the biomass thermal degradation. TGA and DTG (Derivative thermogravimetry) indicated that the maximum degradation temperatures increased after acid pretreatment due to the minerals catalytic effects. The main permanent evolved gases comprising H 2 , CO 2 , CO were detected online during analysis. The major permanent gases produced at the temperature range of 250–750 °C were attributed to the condensable vapors cracking and probably some secondary reactions. The physiochemical structure change of the acid-treated biomass samples was examined by using Brunauer Emmett Teller (BET) method, Scanning Electron Microscope (SEM) and FTIR. The pyrolysis kinetics of the different palm oil biomasses were investigated using first order reaction model

  8. Mechanical alloying of Hf and Fe powders

    International Nuclear Information System (INIS)

    Mendoza Zelis, L.; Crespo, E.; Creus, M.; Damonte, L.C.; Sanchez, F.H.; Punte, G.

    1994-01-01

    Pure crystalline Hf and Fe powders were mixed and milled under an argon atmosphere. The evolution of the system with milling time was followed with Moessbauer effect spectroscopy and X-ray diffraction. The results indicate that in the first stages an amorphous Fe-rich alloy was gradually formed together with a solid solution of Hf in Fe beyond the solubility limit. (orig.)

  9. Developing Effective Separation of Feldspar and Quartz While Recycling Tailwater by HF Pretreatment

    Directory of Open Access Journals (Sweden)

    Weiqing Wang

    2018-04-01

    Full Text Available The effect of hydrofluoric acid (HF pretreatment on flotation of feldspar and quartz using dodecylamine (DDA as collector was investigated by micro-flotation, zeta potential, pyrene fluorescence spectroscopy, attenuated total reflection flourier transformed infrared spectroscopy (ATR-FTIR, scanning electron microscope (SEM, X-ray photoelectron spectroscopy (XPS and bench scale flotation. The micro-flotation tests revealed that there was little difference in the flotation of feldspar and quartz at pH 2, using H2SO4 as pH regulator. After HF pretreatment, the floatability of feldspar significantly increased while the floatability of quartz showed no change. HF pretreatment resulted in leaching of SiO2 and enrichment of Na, K and Al on the feldspar surface. Consequently, the negative surface charge of feldspar increased at pH 2, which allowed for the flotation separation of the feasible minerals. This took place via an increased electrostatic adsorption between DDA and Na, K, Al on the feldspar surface, which effectively increased its hydrophobicity and as a result, improved the floatability of feldspar. An alternative process which exhibited effective separation of quartz and feldspar while recycling the tailwater from the flotation was proposed.

  10. A TEMPERATURE- AND COMPOSITION-DEPENDENT STUDY, OF H2SO4 AEROSOL OPTICAL CONSTANTS USING FOURIER TRANSFORM AND TUNABLE DIODE LASER INFRARED SPECTROSCOPY. (R826767)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  11. Effect of corrosion product layer on SCC susceptibility of copper containing type 304 stainless steel in 1 M H2SO4

    International Nuclear Information System (INIS)

    Asawa, M.; Devasenapathi, A.; Fujisawa, M.

    2004-01-01

    The effect of surface corrosion product layer on the stress corrosion cracking (SCC) susceptibility of type 304 stainless steel with Cu was studied in 1 kmol/m 3 (1 M) sulfuric acid at 353 K temperature. Studies based on the intermittent removal of surface corrosion product layer indicated that the surface film governs the SCC behavior of the alloy by accelerating both the crack initiation and propagation stages. The electrochemical impedance and polarization studies showed the surface layer to be promoting SCC initiation by lowering the uniform corrosion rate and the propagation by shifting the surface corrosion potential to a more noble direction. The elemental analysis of the corrosion product both by the energy dispersive X-ray (EDX) spectroscopy and by X-ray diffraction (XRD) analysis along with the thermodynamic calculations showed the layer to be constituted mainly of metallic copper (Cu) and the mono-hydrated iron sulfate which acts as cathode promoting SCC

  12. African biomass burning plumes over the Atlantic: aircraft based measurements and implications for H2SO4 and HNO3 mediated smoke particle activation

    Directory of Open Access Journals (Sweden)

    A. Dörnbrack

    2011-04-01

    Full Text Available Airborne measurements of trace gases and aerosol particles have been made in two aged biomass burning (BB plumes over the East Atlantic (Gulf of Guinea. The plumes originated from BB in the Southern-Hemisphere African savanna belt. On the day of our measurements (13 August 2006, the plumes had ages of about 10 days and were respectively located in the middle troposphere (MT at 3900–5500 m altitude and in the upper troposphere (UT at 10 800–11 200 m. Probably, the MT plume was lifted by dry convection and the UT plume was lifted by wet convection. In the more polluted MT-plume, numerous measured trace species had markedly elevated abundances, particularly SO2 (up to 1400 pmol mol−1, HNO3 (5000–8000 pmol mol−1 and smoke particles with diameters larger than 270 nm (up to 2000 cm−3. Our MT-plume measurements indicate that SO2 released by BB had not experienced significant loss by deposition and cloud processes but rather had experienced OH-induced conversion to gas-phase sulfuric acid. By contrast, a significant fraction of the released NOy had experienced loss, most likely as HNO3 by deposition. In the UT-plume, loss of NOy and SO2 was more pronounced compared to the MT-plume, probably due to cloud processes. Building on our measurements and accompanying model simulations, we have investigated trace gas transformations in the ageing and diluting plumes and their role in smoke particle processing and activation. Emphasis was placed upon the formation of sulfuric acid and ammonium nitrate, and their influence on the activation potential of smoke particles. Our model simulations reveal that, after 13 August, the lower plume traveled across the Atlantic and descended to 1300 m and hereafter ascended again. During the travel across the Atlantic, the soluble mass fraction of smoke particles and their mean diameter increased sufficiently to allow the processed smoke particles to act as water vapor condensation nuclei already at very low water vapor supersaturations of only about 0.04%. Thereby, aged smoke particles had developed a potential to act as water vapor condensation nuclei in the formation of maritime clouds.

  13. Laboratory Study of H2SO4 / H2O Nucleation Using a New Technique - a Laminar Co-Flow Tube.

    Czech Academy of Sciences Publication Activity Database

    Trávníčková, Tereza; Škrabalová, Lenka; Havlica, Jaromír; Krejčí, A. Petr; Hrubý, Jan; Ždímal, Vladimír

    2018-01-01

    Roč. 70, č. 1 (2018), s. 1446643 ISSN 0280-6509 R&D Projects: GA ČR(CZ) GAP105/12/0664; GA ČR(CZ) GA17-19798S; GA MŠk(CZ) EF16_013/0001315 EU Projects: European Commission(XE) 315760 - HEXACOMM; European Commission(XE) 654109 - ACTRIS-2 Institutional support: RVO:67985858 ; RVO:61388998 Keywords : co-flow * nucleation * sulphuric acid Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry

  14. Temperature-Dependent Diffusion of H2SO4 in Air at Atmospherically Relevant Conditions: Laboratory Measurements Using Laminar Flow Technique.

    Czech Academy of Sciences Publication Activity Database

    Brus, David; Škrabalová, Lenka; Herrmann, E.; Olenius, T.; Trávníčková, Tereza; Makkonen, U.; Merikanto, J.

    2017-01-01

    Roč. 8, č. 7 (2017), č. článku 132. ISSN 2073-4433 R&D Projects: GA ČR GAP209/11/1342 Grant - others:ERC(FI) 257360; AFCE(FI) 272041; GA AF(FI) 288440 Institutional support: RVO:67985858 Keywords : diffusion coefficient * sulfuric acid * laminar flow tube Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.487, year: 2016

  15. Toward elimination of discrepancies between theory and experiment: The rate constant of the atmospheric conversion of SO3 to H2SO4

    Science.gov (United States)

    Loerting, Thomas; Liedl, Klaus R.

    2000-01-01

    The hydration rate constant of sulfur trioxide to sulfuric acid is shown to depend sensitively on water vapor pressure. In the 1:1 SO3-H2O complex, the rate is predicted to be slower by about 25 orders of magnitude compared with laboratory results [Lovejoy, E. R., Hanson, D. R. & Huey, L. G. (1996) J. Phys. Chem. 100, 19911–19916; Jayne, J. T., Pöschl, U., Chen, Y.-m., Dai, D., Molina, L. T., Worsnop, D. R., Kolb, C. E. & Molina, M. J. (1997) J. Phys. Chem. A 101, 10000–10011]. This discrepancy is removed mostly by allowing a second and third water molecule to participate. An asynchronous water-mediated double proton transfer concerted with the nucleophilic attack and a double proton transfer accompanied by a transient H3O+ rotation are predicted to be the fastest reaction mechanisms. Comparison of the predicted negative apparent “activation” energies with the experimental finding indicates that in our atmosphere, different reaction paths involving two and three water molecules are taken in the process of forming sulfate aerosols and consequently acid rain. PMID:10922048

  16. HF i dag

    DEFF Research Database (Denmark)

    Lindstrøm, Maria Duclos; Simonsen, Birgitte

    2008-01-01

    Notatet er lavet på baggrund af uddannelsesbiografiske dybdeinterviews med kursister på toårigt HF. Indenfor rammerne af en pilotundersøgelse identificerer notatet fire gennemgående profiler: De pragmatiske, de fagligt usikre, second chance-kursisterne, og de HF-kursister, som har HF som first...

  17. Zirconium Zr and hafnium Hf

    International Nuclear Information System (INIS)

    Busev, A.I.; Tiptsova, V.G.; Ivanov, V.M.

    1978-01-01

    The basic methods for extracting and determining Zr(4) and Hf(4) are described. Diantipyrinemethane and its alkyl homologs selectively extract Zr and Hf from HNO 3 solutions in the presence of nitrates. Zr is selectively extracted with tetraethyldiamide of heptyl phosphoric acid (in benzene) as well as with 2-thenoyltrifluoroacetone (in an acid). The latter reagents is suitable for rapid determination of 95 Zr in a mixture with 95 Nb and other fragments. The complexometric determination of Zr is based on formation of a stable complex of Zr with EDTA. The titration is carried out in the presence of n-sulfobenzene-azo-pyrocatechol, eriochrome black T. The determination is hindered by Hf, fluoride-, phosphate-, oxalate- and tartrate-ions. The method is used for determining Zr in zircon and eudialyte ore. Zr is determined photometrically with the aid of xylenol orange, arsenazo 3 and pyrocatechol violet (in phosphorites). Hf is determined in the presence of Zr photometrically with the aid of xylenol orange or methyl-thymol blue. The method is based on Zr being masked with hydrogen peroxide in the presence of sulfate-ions

  18. Desorption of 137Cs from Cetraria islandica (L. Ach. using solutions of acids and their salts mixtures

    Directory of Open Access Journals (Sweden)

    ANA A. ČUČULOVIĆ

    2009-06-01

    Full Text Available The desorption of 137Cs from Cetraria islandica (L. Ach. lichen was investigated using the solutions: A H2SO4–HNO3–K2SO4, B H2SO4–HNO3–Na2SO4 and C H2SO4–HNO3– (NH42SO4–(NH4NO3 at pH 2.00, 2.58, 2.87, 3.28 and 3.75, similar to acid rain. After five consecutive desorptions using solutions A, B and C, from 44.0 % (solution B, pH 3.75 to 68.8 % (solution C, pH 3.28 of 137Cs had been desorbed from the lichen. In all cases, the most successful 137Cs desorption was the first one. In the presence of K+ (solution A the total amount of desorbed 137Cs did not depend on the pH of the solution and this was confirmed by the analogous reactions of Cs+ and K+, due to their similar ionic radii. The dependencies of the non-desorbed content of 137Cs on the number of desorptions gave curves indicating that at least two types of sorption occur. One of them can be dominant if suitable desorbants are used. The results indicate lichens as secondary sources of environment pollution with 137Cs.

  19. Separation of zirconium (Zr) and hafnium (Hf) using solvent mixture of TBP-D_2EHPA and amberlite XAD-16

    International Nuclear Information System (INIS)

    Dwi Biyantoro; I Made Sukarna; Agus Suyanto

    2017-01-01

    The aims of this research were to determine the composition (ratio of extractant and resin) of the SIR which is effective for the separation of Zr and Hf, knowing adsorption equilibrium models Zr and Hf using the SIR, and knowing the most effective adsorption results from SIR weight ratio. The research was conducted by using the SIR method that is impregnating the extractant into the resin. Extractant used is a mixture of TBP and D_2EHPA (1 : 3), the resin used is XAD-16, and the feed used is ZOC. This research was conducted by varying the composition of the SIR, after the result of effective SIR variation. Adsorption process is then performed using the ZOC with SIR. Then filtered, the filtrate was analyzed by XRF. While solids SIR adsorption product was desorbed using sulfuric acid. Then the desorption results were analyzed using XRF spectrometer. Based on calculations, the results of the most effective SIR composition for the separation of Zr-Hf are comparison extractant and resin = 5:5 either for the dry method and wet method, the equilibrium equations for Zr approaching Langmuir equilibrium models while the equilibrium equation for Hf approaching Freundlich equilibrium models which the most effective adsorption results that bait comparison with the SIR = 10 mL : 5 g with β = 0.1831; η Zr = 26.39 % and η Hf = 66.19 % for dry method and β = 0.1557; η Zr = 25.17 % and η Hf = 68.36 % for wet method. From result desorption process was 2 M H_2SO_4. (author)

  20. First-principles calculations of the structural and thermodynamic properties of bcc, fcc and hcp solid solutions in the Al-TM (TM = Ti, Zr and Hf) systems: A comparison of cluster expansion and supercell methods

    International Nuclear Information System (INIS)

    Ghosh, G.; Walle, A. van de; Asta, M.

    2008-01-01

    The thermodynamic properties of solid solutions with body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed (hcp) structures in the Al-TM (TM = Ti, Zr and Hf) systems are calculated from first-principles using cluster expansion (CE), Monte-Carlo simulation and supercell methods. The 32-atom special quasirandom structure (SQS) supercells are employed to compute properties at 25, 50 and 75 at.% TM compositions, and 64-atom supercells have been employed to compute properties of alloys in the dilute concentration limit (one solute and 63 solvent atoms). In general, the energy of mixing (Δ m E) calculated by CE and dilute supercells agree very well. In the concentrated region, the Δ m E values calculated by CE and SQS methods also agree well in many cases; however, noteworthy discrepancies are found in some cases, which we argue originate from inherent elastic and dynamic instabilities of the relevant parent lattice structures. The importance of short-range order on the calculated values of Δ m E for hcp Al-Ti alloys is demonstrated. We also present calculated results for the composition dependence of the atomic volumes in random solid solutions with bcc, fcc and hcp structures. The properties of solid solutions reported here may be integrated within the CALPHAD formalism to develop reliable thermodynamic databases in order to facilitate: (i) calculations of stable and metastable phase diagrams of binary and multicomponent systems, (ii) alloy design, and (iii) processing of Al-TM-based alloys

  1. Effect of octanols structure on their extraction ability as regards to rhenium(VII) in sulfuric acid solutions

    International Nuclear Information System (INIS)

    Kasikov, A.G.; Petrova, A.M.

    2007-01-01

    It is established that extraction ability of octanols as regards to rhenium(VII) and sulfuric acid depends on the structure of alcohol, but if in passage from octanol-1 to octanol-3 as regard to rhenium(VII) it rises, then for H 2 SO 4 it falls. Dependence of the distribution function of rhenium from the concentration of the acid has maximums at 4-7 mol l 1- that the most distinctly it becomes apparent for secondary alcohols. Decreasing the extraction ability of octyl alcohols with the growth of H 2 SO 4 concentration more than 7 mol l 1- is connected with the change of extractant composition and forms of rhenium(VII) being in the solution [ru

  2. Novel precipitation technique for uranium recovery from carbonate leach solutions

    International Nuclear Information System (INIS)

    Sujoy Biswas; Rupawate, V.H.; Hareendran, K.N.; Roy, S.B.; Chakravartty, J.K.

    2015-01-01

    The recovery of uranium from carbonate ore leach solution was studied using novel precipitation method. The uranium from leach liquor was recovered as magnesium diuranate with NaOH in presence of trace amount of Mg 2+ . Effects of various parameters such as addition of H 2 SO 4 , MgO, MgSO 4 as well as NaOH were investigated for maximum uranium recovery. Overall uranium recovery of the process was 97 % with improved particle size (∼57 µm). Based on the experimental findings, a process flow-sheet was developed for uranium recovery from carbonate ore leach solution with a uranium concentration of <1 g/L. (author)

  3. Surface coverage and corrosion inhibition effect of Rosmarinus officinalis and zinc oxide on the electrochemical performance of low carbon steel in dilute acid solutions

    Science.gov (United States)

    Loto, Roland Tolulope

    2018-03-01

    Electrochemical analysis of the corrosion inhibition and surface protection properties of the combined admixture of Rosmarinus officinalis and zinc oxide on low carbon steel in 1 M HCl and H2SO4 solution was studied by potentiodynamic polarization, open circuit potential measurement, optical microscopy and ATR-FTIR spectroscopy. Results obtained confirmed the compound to be more effective in HCl solution, with optimal inhibition efficiencies of 93.26% in HCl and 87.7% in H2SO4 acid solutions with mixed type inhibition behavior in both acids. The compound shifts the corrosion potential values of the steel cathodically in HCl and anodically in H2SO4 signifying specific corrosion inhibition behavior without applied potential. Identified functional groups of alcohols, phenols, 1°, 2° amines, amides, carbonyls (general), esters, saturated aliphatic, carboxylic acids, ethers, aliphatic amines, alkenes, aromatics, alkyl halides and alkynes within the compound completely adsorbed onto the steel forming a protective covering. Thermodynamic calculations showed physisorption molecular interaction with the steel's surface according to Langmuir and Frumkin adsorption isotherms. Optical microscopy images of the inhibited and uninhibited steels contrast each other with steel specimens from HCl solution showing a better morphology.

  4. Surface coverage and corrosion inhibition effect of Rosmarinus officinalis and zinc oxide on the electrochemical performance of low carbon steel in dilute acid solutions

    Directory of Open Access Journals (Sweden)

    Roland Tolulope Loto

    2018-03-01

    Full Text Available Electrochemical analysis of the corrosion inhibition and surface protection properties of the combined admixture of Rosmarinus officinalis and zinc oxide on low carbon steel in 1 M HCl and H2SO4 solution was studied by potentiodynamic polarization, open circuit potential measurement, optical microscopy and ATR-FTIR spectroscopy. Results obtained confirmed the compound to be more effective in HCl solution, with optimal inhibition efficiencies of 93.26% in HCl and 87.7% in H2SO4 acid solutions with mixed type inhibition behavior in both acids. The compound shifts the corrosion potential values of the steel cathodically in HCl and anodically in H2SO4 signifying specific corrosion inhibition behavior without applied potential. Identified functional groups of alcohols, phenols, 1°, 2° amines, amides, carbonyls (general, esters, saturated aliphatic, carboxylic acids, ethers, aliphatic amines, alkenes, aromatics, alkyl halides and alkynes within the compound completely adsorbed onto the steel forming a protective covering. Thermodynamic calculations showed physisorption molecular interaction with the steel’s surface according to Langmuir and Frumkin adsorption isotherms. Optical microscopy images of the inhibited and uninhibited steels contrast each other with steel specimens from HCl solution showing a better morphology. Keywords: Corrosion, Inhibitor, Adsorption, Steel, Acid

  5. HF-laser program

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    Sandia's HF-laser program for FY 77 and FY 78 was revised in June 1977 in order to meet several new program milestones. Research progress is reported on: objective of HF oscillator-amplifier studies using H 2 -F 2 gas mixtures; characteristics of large-volume oscillator using H 2 -F 2 mixtures; characteristics of large-volume amplifier using H 2 -F 2 mixtures; experimental results of the oscillator-amplifier study; objective of high-quality discharge-initiated SF 6 -HI oscillator-preamplifier system; pin-discharge-initiated oscillator and first beam expander; fast-discharge-initiated preamplifiers; reflecting beam expanders for oscillator-preamplifier system; beam quality of discharge-initiated oscillator-preamplifier system; short pulse option for discharge initiated SF 6 -HI system; H 2 -F 2 electron-beam-initiated oscillator-preamplifier system; chamber for HF-laser focusing experiments; computer study of parasitic oscillations in HF amplifiers and oscillators; kinetics upgrade of HF-laser code; repetitivey ignited flowing H 2 -F 2 -O 2 mixtures; spontaneous detonations in multiatmosphere H 2 -F 2 -O 2 mixtures; high-pressure H 2 -F 2 laser studies; and time sequenced energy extraction on the high xenon laser

  6. Process for uranium separation and preparation of UO4.2NH3.2HF

    International Nuclear Information System (INIS)

    Dokuzoguz, H.Z.

    1976-01-01

    A process for treating the aqueous effluents that are produced in converting gaseous UF 6 (uranium hexafluoride) into solid UO 2 (uranium dioxide) by way of an intermediate (NH 4 ) 4 UO 2 (CO 3 ) 3 (''AUC'' Compound) is disclosed. These effluents, which contain large amounts of NH 4 + , CO 3 2- , F - , and a small amount of U are mixed with H 2 SO 4 (sulfuric acid) in order to expel CO 2 (carbon dioxide) and thereby reduce the carbonate concentration. The uranium is precipitated through treatment with H 2 O 2 (hydrogen peroxide) and the fluoride is easily recovered in the form of CaF 2 (calcium fluoride) by contacting the process liquid with CaO (calcium oxide). The presence of SO 4 2- (sulfate) in the process liquid during CaO contacting seems to prevent the development of a difficult-to-filter colloid. The process also provides for NH 3 recovery and recycling. Liquids discharged from the process, moreover, are essentially free of environmental pollutants. The waste treatment products, i.e., CO 2 , NH 3 , and U are economically recovered and recycled back into the UF 6 → UO 2 conversion process. The process, moreover, recovers the uranium as a precipitate in the second stage. This precipitate is a new inorganic chemical compound UO 4 .2NH 3 .2HF [uranyl peroxide-2-ammonia-2-(hydrogen fluoride)

  7. PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKAN MIXER SETTLER

    Directory of Open Access Journals (Sweden)

    Dwi Biyantoro

    2017-01-01

    Full Text Available ABSTRAK PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKANMIXER SETTLER. Telah dilakukan pemisahanZr – Hf secara sinambung menggunakan pengaduk pengenap (mixer settler 16 stage. Larutan umpan adalah zirkon nitrat dengan kadar Zr = 30786 ppm dan Hf = 499 ppm. Ekstraktan dipakai adalah solven 60 % TBP dalam kerosen dan larutan scrubbingyang dipakai adalah asam nitrat 1 M. Umpan masuk pada stageke 5 dikontakkan secara berlawanan arah dengan solven masuk pada stage ke 16 dan larutan scrubbing masuk pada stage ke 1. Tujuan penelitian ini adalah memisahkan unsur Zr dan Hf dari hasil olah pasir zirkon menggunakan solven TBP dengan alat mixer settler16 stage. Analisis umpan dan hasil proses pemisahan untuk zirkonium (Zr dilakukan dengan menggunakan alat pendar sinar-X, sedangkananalisis unsur hafnium (Hf menggunakan Analisis Pengaktifan Neutron (APN. Parameter penelitian dilakukan dengan variasi keasaman asam nitrat dalam umpan dan variasi waktu pada berbagai laju pengadukan. Hasil penelitian pemisahan unsur Zr dengan Hf diperolehkondisi optimum pada keasaman umpan 4 N HNO3, keseimbangan dicapai setelah 3jam dan laju pengadukan 3300 rpm. Hasil ekstrak  unsur zirkon (Zr diperoleh kadar sebesar 28577 ppm dengan efisiensi 92,76 % serta kadar pengotor hafnium (Hf sebesar 95 ppm. Kata Kunci: pemisahan Zr, Hf, ekstraksi, mixer settler, alat pendar sinar-X, APN. ABSTRACT SEPARATION of Zr - Hf CONTINUOUSLY USE THE MIXER SETTLER. Separation of Zr - Hf continuously using mixer settler 16 stage has been done. The feed solution is zircon nitrate concentration of Zr = 30786 ppm  and Hf = 499 ppm. As the solvent used extractant 60 % TBP in 40 % kerosene. Nitric acid solution used srubbing 1 M. The feed entered into stage to 5 is contacted with solvents direction on the stage to 16 and the scrubbing solution enter the stage to 1. The purpose of this study is to separate Zr and Hf of the results from the process of zircon sand using solvent TBP using 16 stage

  8. HF/DF chemical labs

    International Nuclear Information System (INIS)

    Meinzer, R.A.

    1987-01-01

    This paper provides the essential details to understand and design HF/DF and related types of chemical lasers. The basic operation of the HF/DF chemical laser is described. The details of the excitation chemistry are presented and the pertinent laser physics is described. A description of the various laser components is given and the analytical models for the HF/DF chemical laser are discussed. A brief description of the chain reaction HF/DF chemical laser is offered

  9. Isothermal cross-sections of Hf-Sc-Ga(800 deg C) and Hf-Ti-Ga (750 deg C) phase diagrams

    International Nuclear Information System (INIS)

    Markiv, V.Ya.; Belyavina, N.N.

    1981-01-01

    Isothermal cross sections of Hf-Sc-Ga (800 deg C) and Hf-Ti-Ga (750 deg C) state diagrams are plotted. The existence of two ternary Hfsub(0.1-0.8)Scsub(0.9)-sub(0.2)Ga and Hfsub(0.8)Scsub(0.2)Gasub(3) phases is stated in the Hf-Sc-Ga system. The crystal structure of these compounds investigated by the powder method belongs to the structural α-MoB and ZrAl 3 types respectively. Continuous rows of (Hf, Sc 5 Ga 5 , (Hf, Ti)Ga 3 and (Hf, Ti)Ga 2 solid solutions are formed in the investigated systems. Essential quantity of the third component dissolve binary Sc 5 Ga 4 , Sc 2 Ga 3 (15 and 30 at % Hf respectively), Hf 5 Ga 4 , HfGa 2 (20, 10 at. % Sc), Hf 5 Ga 4 , HfGa, Hf 5 Ga 3 , Hf 2 Ga 3 (48, 30, 46, 20 at. % Ti) gallides [ru

  10. Opto-electrochemical spectroscopy of metals in aqueous solutions

    International Nuclear Information System (INIS)

    Habib, K.

    2016-01-01

    In the present investigation, holographic interferometry was utilized for the first time to determine the rate change of the electrical resistance of aluminium samples during the initial stage of anodisation processes in aqueous solution. In fact, because the resistance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the resistance was called electrical resistance–emission spectroscopy. The anodisation process of the aluminium samples was carried out by electrochemical impedance spectroscopy (EIS) in different sulphuric acid concentrations (1.0%–2.5% H 2 SO 4 ) at room temperature. In the meantime, the real time holographic interferometry was used to determine the difference between the electrical resistance of two subsequent values, dR, as a function of the elapsed time of the EIS experiment for the aluminium samples in 1.0%, 1.5%, 2.0%, and 2.5% H 2 SO 4 solutions. The electrical resistance–emission spectra of the present investigation represent a detailed picture of not only the rate change of the electrical resistance throughout the anodisation processes but also the spectra represent the rate change of the growth of the oxide films on the aluminium samples in different solutions. As a result, a new spectrometer was developed based on the combination of the holographic interferometry and electrochemical impedance spectroscopy for studying in situ the electrochemical behavior of metals in aqueous solutions.

  11. Solution spectroelectrochemical cell for in situ X-ray absorption fine structure

    International Nuclear Information System (INIS)

    Antonio, M.R.; Soderholm, L.

    1995-01-01

    A purpose-built spectroelectrochemical cell for in situ fluorescence XAFS (X-ray Absorption Fine Structure) measurements of bulk solution species during constant-potential electrolysis is described. The cell performance was demonstrated by the collection of europium L 3 -edge XANES (X-ray Absorption Near Edge Structure) throughout the course of electrolysis of an aqueous solution of EuCl 3 ·6H 2 O in 1 M H 2 SO 4 . The europium L 3 -edge resonances reported here for the Eu III and Eu II ions demonstrate that their 2p 3/2 → 5d electronic transition probabilities are not the same

  12. Studying titanium-molybdenum-zirconium alloys of increased corrosion resistance in acid solutions

    International Nuclear Information System (INIS)

    Tomashov, N.D.; Kazarin, V.I.; Mikheev, V.S.; Goncharenko, B.A.; Sigalovskaya, T.M.; Kalyanova, M.P.

    1977-01-01

    New promising Ti-Mo-Nb-Zr system alloys, possessing good workability and a high corrosion resistance in non-oxidizing solutions of acids, have been developed. The alloys may be recommended as structural materials for equipment operating in severely agressive acid media, such as hydrochloric, sulphuric and phosphoric acids. The corrosion resistance of alloys of the above system in solutions of H 2 SO 4 , HCl and H 3 PO 4 acids may be maximized by increasing the overall alloying to 42% (keeping the ratio of the alloying components Mo/Nb/Zr=4/1/1 unchanged), while retaining sufficiently good plasticity and workability

  13. Search for chemical separations of the element 106 homologues in HF and HF-HCl media

    International Nuclear Information System (INIS)

    Trubert, D.; Monroy-Guzman, F.; Hussonnois, M.; Brillard, L.; Le Naour, C.; Constantinescu, O.

    1996-01-01

    In order to study the chemical properties of element 263 106 in aqueous media, fast, efficient and reproducible chromatographic separations were tested on its assumed homologous: Mo, W and U. Corroborative static and dynamic off-line experiments have shown that after fixation of these three elements on anion-exchange resin in HF medium, selective elution could be achieved by using suitable concentration of HCl - HF and HCl solutions. Separations of short-lived W isotopes, produced through heavy ion irradiation were also performed on-line. (author). 27 refs., 14 figs

  14. Nanosized Hydroxyapatite Precipitation on the Ti—30Ta—xHf Alloys.

    Science.gov (United States)

    Lee, Kang; Jang, Jae- In; Han-Cheol, Choe

    2017-04-01

    In this study, we prepared hydroxyapatite (HAp) layer on the alkali treated Ti–30Ta–xHf alloys using electrochemical deposition method. Ti–30Ta–xHf alloys was anodized in 5 M NaOH solution at 0.3 A for 10 min. Alkali treated Ti–30Ta–xHf surface formed by anodization step which acted as templates and anchorage for growth of the HAp during subsequent pulsed electrochemical deposition process at 85 °C. The phase and morphologies of deposited HAp layer were affected by the Hf contents of Ti–30Ta–xHf alloys. The nano-scale rod-like HAp layer was formed on untreated Ti–30Ta–xHf alloys with partially low crystallinity. In the case of alkali treated Ti–30Ta–xHf, nano-sized needle-like layers were transferred to nano-flake surface and denser morphology as Hf content increased.

  15. HF-laser program

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    The HF laser is an attractive candidate driver for a large-system ICF scientific demonstration facility, for an ICF experimental power reactor and for a commercial laser--fusion power reactor. Previous accomplishments of the program have included demonstrations of high efficiency and high energy capability, efficient energy extraction from HF amplifiers, good beam quality and focusability, and short-pulse generation and amplification. In the reporting period, beam quality has been determined to be near-diffraction limited for a short pulsewidth (6 ns to 25 ns) oscillator-amplifier chain, suppression of amplified spontaneous emission has been demonstrated on an individual spectral line, high-pressure characteristics have been determined for the Phoenix I amplifier, and detailed comparisions between the kinetic code and experiments have been made. Details of two major upcoming experiments are also included. The first is energy extraction and beam quality measurements on the Phoenix I amplifier operating under saturated output power conditions. The second experiment, using a newly designed amplifier (Phoenix II), is designed to demonstrate the concept of angular-multiplexing: a pulse width-compression scheme

  16. Pulsed inductive HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

  17. Resistência química de vitro-cerâmicos pertencentes a sistemas Li2O-ZrO2-BaO-SiO2 frente ao tratamento com soluções ácidas e básicas Chemical durability of the Li2O-ZrO2-BaO-SiO2 glass-ceramic treated with acidic and basic solution

    Directory of Open Access Journals (Sweden)

    Silvia Denofre de Campos

    2002-05-01

    Full Text Available The chemical durability of the Li2O-ZrO2-BaO-SiO2 system was examined by determination of the Vickers hardness. The dependence of hardness and of the chemical resistance with BaO addition was investigated. The experimental results indicate that the hardness increases with the BaO content. The samples surface's morphology submitted to the chemical treatment in acidic (H2SO4 and basic (KOH solution was accompanied by scanning electron microscopy. The chemical durability of the materials with BaO showed better than the glass ceramic without this content. These materials treated with H2SO4 solution showed a preferential attack to the silica rich sites.

  18. HF-DLLME

    OpenAIRE

    Simão, Vanessa

    2015-01-01

    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2015. Neste trabalho foi proposto, pela primeira vez, a combinação simultânea das técnicas de microextração em fase líquida suportada em fibra oca (HF-LPME) e microextração líquido-líquido dispersiva (DLLME) para aplicação em amostras líquidas. Dois estudos foram desenvolvidos utilizando a metodologia proposta, a qua...

  19. High energy HF pulsed lasers

    International Nuclear Information System (INIS)

    Patterson, E.L.; Gerber, R.A.

    1976-01-01

    Recent experiments show that pulsed HF lasers are capable of producing high energy with good efficiency. Preliminary experiments show that the laser radiation from the high-gain medium can be controlled with a low-power probe laser beam or with low-level feedback. These results indicate that the HF laser may have potential for second-generation laser fusion experiments

  20. Temperature influence on corrosion rate of armco iron in acid solutions

    International Nuclear Information System (INIS)

    Perboni, G.; Rocchini, G.

    1986-01-01

    An experimental study of the behaviour of Armco iron and several steels in acid solutions (HCl, H 2 SO 4 , H 3 PO 4 ) has been undertaken to determine the temperature effect on dissolution rate. The test temperatures were 30, 45, 60, 75 and 90 deg C. The activation heat was determined by application of the Arrhenius law from colorimetric and electrochemical data. Investigation results obtained by both methods were represented diagrammatically and showed a good agreement, though the discrepancy in the data increased with test temperature

  1. Helium implanted AlHf as studied by 181 Ta TDPAC

    Indian Academy of Sciences (India)

    Measurements on helium implanted sample indicate the binding of helium associated defects by Hf solute clusters. Isochronal annealing measurements indicate the dissociation of the helium implantation induced defects from Hf solute clusters for annealing treatments beyond 650 K. On comparison of the present results ...

  2. Concentration of rhenium from dilute sodium chloride solutions

    Directory of Open Access Journals (Sweden)

    DRAGOLJUB M. LUKIC

    2008-03-01

    Full Text Available The conditions for the desorption of rhenium from the anion exchange resin Dowex 1-x8 by HNO3, HCl, H2SO4 and NaOH were determined. The solution (5.0´10-3 mol dm-3 Re in 0.15 mol dm-3 NaCl was passed through a column containing 0.10 g of the resin. The total sorbed amount of rhenium was 0.20 g/g of the resin. It was then eluted by the corresponding eluent in the concentration range up to about 3.0 mol dm-3. The highest elution efficiency and the most favourable elution profile were found with 3.0 mol dm-3 HNO3. Over 77 % of the sorbed rhenium was found in the first 5 ml of the eluate. Practically all the rhenium was recovered with 20 ml of the acid. Under the given experimental conditions, HCl and H2SO4 were less favourable while NaOH was not applicable, due to very low efficiency of rhenium elution.

  3. Thermodynamic modeling of the Co–Hf system supported by key experiments and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xingxu [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Liu, Shuhong, E-mail: shhliu@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Sino-German Cooperation Group “Microstructure in Al alloys”, Central South University, Changsha, Hunan 410083 (China); Cheng, Kaiming; Tang, Ying [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Ou, Pengfei [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Nash, Philip [Thermal Processing Technology Center, Illinois Institute of Technology (IIT), 10 West 32nd Street, Chicago, IL 60616 (United States); Sundman, Bo [INSTN, CEA Saclay, 91191 Gif-Sur-Yvette Cedex (France); Du, Yong [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Sino-German Cooperation Group “Microstructure in Al alloys”, Central South University, Changsha, Hunan 410083 (China); Zheng, Feng [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China)

    2015-05-20

    Highlights: • Heat contents of Co{sub 2}Hf and CoHf{sub 2} were measured by drop calorimetry. • Enthalpy of formation for Co{sub 23}Hf{sub 6} was computed via first-principles calculations. • Co–Hf system was assessed by means of CALPHAD approach. • Order–disorder model is used to describe B2 (CoHf) and A2 (βHf). • Glass forming range of the Co–Hf amorphous alloys was predicted. - Abstract: Phase equilibria and thermodynamic properties of the Co–Hf system were investigated via calorimetric measurements, first-principles calculations and thermodynamic modeling. Heat contents of Co{sub 2}Hf and CoHf{sub 2} were measured by drop calorimetry from 300 to 1200 °C. The enthalpy of formation for Co{sub 23}Hf{sub 6} at 0 K was computed via first-principles calculations. Based on the experimental measurements and first-principles calculations from the present work and the literature, the Co–Hf system was assessed by means of CALPHAD (CALculation of PHAse Diagram) approach. The excess Gibbs energy of solution phases was modeled with Redlich–Kister polynomial. Sublattice models were employed to describe the homogeneity ranges of Co{sub 2}Hf, CoHf and CoHf{sub 2}. The order–disorder transition between B2 (CoHf) and A2 (βHf) phases was taken into account in the current optimization. Using the optimized parameters, glass forming range (GFR) of the Co–Hf amorphous alloys was predicted to be 15–75 at.% Hf, which is in satisfactory agreement with the experimental observation.

  4. Hf på VUC

    DEFF Research Database (Denmark)

    Pless, Mette; Hansen, Niels-Henrik Møller

    . Konkret har forskningsprojektet 3 mål: At afdække hf-kursisternes tidligere uddannelsesforløb og -erfaringer, før de starter på hf på VUC.At afdække, hvordan mødet med uddannelsens studiemiljø opleves af kursisterne, og ikke mindst kursisternes oplevelse af undervisningsformer, lærere mm.At afdække, hvad...

  5. Extraction of HCl, HBr, HNO3, HClO4, H2SO4 and CH3COOH by 4-(5-monyl)pyridine and 2-hexylpyridine in benzene and determination of their pKsub(BHsup(+)) values

    International Nuclear Information System (INIS)

    Shamim, Chaudri A.; Ahmed, R.; Ejaz, M.

    1977-01-01

    Attempts have been made to indicate briefly some of the factors involved in the extraction processes of mineral acids by the pyridines. In this attempt some factors have been omitted, like dissociation of the extracted species in the organic phase, a mutual interaction between the extractant and solvent, the temperature on the extraction eqequilibrium etc. The results show that larger, less basic anions extract better (ClO 4 - >CH 3 COO - >NO 3 - >Br - >Cl - >HSO 4 - ) due to their low aqueous hydration. The ionization constants of NPyH + and HPyH + as determined spectrophotometrically were found to be 5.97+-0.06 and 5.94+-0.05, respectively, at 25 deg C. (T.G.)

  6. Elimination par électrodialyse des ions Fe(II) d'une solution d'acide ...

    African Journals Online (AJOL)

    Administrateur

    concentration de l'acide (H2SO4) et la température sur l'efficacité d'élimination de Fe(II) a été étudiée. Les .... C. Negro et al. [20] ont étudié la possibilité de récupérer l'acide sulfurique à partir de solution d'acide sulfurique contenant du sulfate de cuivre. L. Cifuentes et al. ..... removal from rinsing water after metal etching,.

  7. MoS2 Nanocube structures as catalysts for electrochemical H2 evolution from acidic aqueous solutions

    OpenAIRE

    Maijenburg, A.W.; Regis, M.; Hattori, A.N.; Tanaka, H.; Choi, K.-S.; ten Elshof, Johan E.

    2014-01-01

    Core–shell PMMA–Au nanocube structures made by a combination of nanoimprint lithography and sidewall deposition were used as template for electrodeposition of MoS2, Ni, and Pt. Linear sweep voltammetry experiments obtained in an aqueous solution containing 0.29 M H2SO4 (pH 0.24) showed that the onset potential of the core–shell–shell PMMA–Au–MoS2 nanocube electrode for the hydrogen evolution reaction (HER) was shifted to the positive direction (i.e., requiring a lower overpotential) by 20–40 ...

  8. Enhanced catalytic performance of Pd catalyst for formic acid electrooxidation in ionic liquid aqueous solution

    Science.gov (United States)

    Feng, Yuan-Yuan; Yin, Qian-Ying; Lu, Guo-Ping; Yang, Hai-Fang; Zhu, Xiao; Kong, De-Sheng; You, Jin-Mao

    2014-12-01

    A protic ionic liquid (IL), n-butylammonium nitrate (N4NO3), is prepared and employed as the electrolyte for formic acid electrooxidation reaction (FAOR) on Pd catalysts. The oxidation peak potential of FAOR in the IL solution shows about a 200 mV negative shift as compared with those in traditional H2SO4/HClO4 electrolytes, suggesting that FAOR can be more easily carried out on Pd catalysts in IL media. The catalytic properties of Pd toward FAOR are not only dependent on the concentration of IL, as a consequence of the varied electronic conductivity of the IL solution, but also on the high potential limit of the cyclic voltammograms. When the Pd catalyst is cycled up to 1.0 V (vs. SCE), which induces a significant oxidation of Pd, it shows ca. 4.0 times higher activity than that not subjected to the Pd oxidation (up to 0.6 V). The Pd oxides, which are more easily formed in IL solution than in traditional H2SO4/HClO4 electrolytes, may play a crucial role in increasing the catalytic activities of Pd toward FAOR. Our work would shed new light on the mechanism of FAOR and highlight the potential applications of IL as green and environment-friendly electrolytes in fuel cells and other technologies.

  9. Beta decomposition processes in Hf-rich Hf--Nb alloys

    International Nuclear Information System (INIS)

    Jones, W.B.; Taggart, R.; Polonis, D.H.

    1978-01-01

    The decomposition of the bcc β-phase by both athermal and isothermal processes has been investigated in Hf-rich Hf--Nb alloys. An all β-phase structure is retained in chill-cast alloys containing 30 to 50 at.% Nb (Cb), although electron diffraction streaking effects and the behavior of the temperature coefficient of electrical resistivity indicate the presence of a bcc lattice instability similar to that reported in solute lean Ti and Zr alloys. Aging a Hf 0 . 65 Nb 0 . 35 alloy at 400 and 600 0 C resulted in the direct precipitation of a fine dispersion of α-phase needles; this morphology differs from the discs of transition α (α/sub t/) which Carpenter et al observed in Nb-rich Nb 0 . 68 Hf 0 . 32 . During continued aging, the needles grow selectively to form colonies or groups of needles in which both the individual needles and the groups of needles have major axes aligned along (110)/sub β/ type directions. The initial α-phase particles exhibit the Burgers orientation relationship with the parent matrix; continued aging changes the electron diffraction patterns in a way that is similar to that observed in aged Ti--Mo and Ti--Mo--Al alloys where they were attributed to the α-phase having a different crystallographic relationship to the β-phase (Type 2 α-phase). The observed changes in the electron diffraction patterns of aged Hf 0 . 65 Nb 0 . 35 cannot be described as resulting from strained Burgers α-phase

  10. Corrosion resistance of tantalum base alloys

    International Nuclear Information System (INIS)

    Gypen, L.A.; Brabers, M.; Deruyttre, A.

    1984-01-01

    The corrosion behaviour of substitutional Ta-Mo, Ta-W, Ta-Nb, Ta-Hf, Ta-Zr, Ta-Re, Ta-Ni, Ta-V, Ta-W-Mo, Ta-W-Nb, Ta-W-Hf and Ta-W-Re alloys has been investigated in various corrosive media, i.e. (1) concentrated sulfuric acid at 250 0 C and 200 0 C, (2) boiling hydrochloric acid of azeotropic composition, (3) concentrated hydrochloric acid at 150 0 C under pressure, (4) HF-Containing solutions and (5) 0.5% H 2 SO 4 at room temperature (anodisation). In highly corrosive media such as concentrated H 2 SO 4 at 250 0 C and concentrated HCl at 150 0 C tantalum is hydrogen embrittled, probably by stress induced precipitation of β-hydride. Both corrosion rate and hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C are strongly influenced by alloying elements. Small alloying additions of either Mo or Re decrease the corrosion rate and the hydrogen embrittlement, while Hf has the opposite effect. Hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C is completely eliminated by alloying Ta with 1 to 3 at % Mo (0.5 to 1.5 wt % Mo). These results can be explained in terms of oxygen deficiency of the Ta 2 O 5 film and the electronic structure of these alloys. (orig.) [de

  11. HF Interference, Procedures and Tools (Interferences HF, procedures et outils)

    Science.gov (United States)

    2007-06-01

    the actual ambient noise floor situation. Besides these HF radio links, special units such as crisis reaction forces are using low power radios for...the origin point on the ground. For ease of arithmetic and typography , the latter option is preferable. The dipole-modelled PLT is located at x = H1

  12. Kinetic determination of As(III in solution

    Directory of Open Access Journals (Sweden)

    TODOR G. PECEV

    2003-10-01

    Full Text Available A new reaction is suggested and a new kinetic method is elaborated for the As(III traces determination in solution, on the basis of their catalyzing effect on komplexon III (EDTA oxidation by KMnO4 in a strong acid solution (H2SO4. Using a spectrophotometric technique, a sensitivity of 72 ng/cm3 As(III was achieved. The relative error of method varies from 5.5 to 13.9 % for As(III concentration range from 83 to 140 ng/cm3. Appropriate kinetic equations are formulated and the influence of some other ions, including the As(V, upon the reaction rate is tested.

  13. The Thermodynamic Characterization of ZrCo–H, HfCo−H, HfNi−H and Zr{sub 1–x}HfxNi(Co) Alloy–H Systems

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, Ted B., E-mail: ted.flanagan@uvm.edu; Noh, Hak; Luo, Suifang

    2016-08-25

    ZrCo and HfCo intermetallic compounds have the same cubic (CsCl-type) structure and their ternary (Zr{sub 1−x}Hf{sub x})Co alloys are also cubic. ZrNi and HfNi intermetallic compounds have the orthorhombic structure (CrB-type) and the ternary (Zr{sub 1−x}Hf{sub x})Ni alloys also have this structure. Thermodynamic data for hydride formation and decomposition in ZrCo, HfCo and HfNi intermetallic compounds have been determined from reaction calorimetry and from pressure-composition isotherms. Thermodynamic data have been determined for the three ternary alloys: (Zr{sub 0.75}Hf{sub 0.25})Co, (Zr{sub 0.50}Hf{sub 0.50})Co, and (Zr{sub 0.25}Hf{sub 0.75})Co and the four ternary alloys: (Zr{sub 0.875}Hf{sub 0.125})Ni, (Zr{sub 0.75}Hf{sub 0.25})Ni, (Zr{sub 0.50}Hf{sub 0.50})Ni, and (Zr{sub 0.25}Hf{sub 0.75})Ni. This offers the opportunity to learn how the thermodynamic properties of the ternary alloy-H systems change with the stoichiometry of alloys with the same structure. - Highlights: • Calorimetric enthalpies determined for H absorption by ZrCo, HfCo, HfNi are determined. • Ternary alloys, e.g., Zr{sub 1−x}Hf{sub x}Ni, prepared and characterized by x-ray diffraction. • Isotherms for the ternary alloys give thermodynamic parameters for H solution.

  14. HF Parameters of Induction Motor

    Directory of Open Access Journals (Sweden)

    M. N. Benallal

    2017-09-01

    Full Text Available This article describes the results of experimental studies of HF input and primary parameters. A simulation model in Matlab SimulinkTM of multiphase windings as ladder circuit of coils is developed. A method for determining the primary parameters of ladder equivalent circuits is presented.

  15. Thermodynamics of HfCl/sub 4/-KCl molten mixtures containing HfCl/sub 4/ up to 33. 3 mol. per cent

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, M V; Salyulev, A B; Kudyakov, V Ya [AN SSSR, Sverdlovsk. Inst. Ehlektrokhimii

    1980-05-01

    Based on measurements of saturated vapour pressure in components of melted mixtures of HfCl/sub 4/-KCl, depending on temperature and concentration, calculated are the results of changes in activity coefficients of hafnium tetrachloride and potassium chloride on transition from diluted solutions, where the Henry law is met, to those concentrated where the law is disobeyed. Growth in the activity coefficient of HfCl/sub 4/ is due to dissociation of complex groups of HfCl/sub 6//sup 2 -/ into complexes with a lesser number of ligands and decreasing relative binding energy of Hf/sup 4 +/-Cl/sup -/ there. In this case, marked changes take place in partial enthalpy and entropy of hafnium tetrachloride mixing. Similar dependences are observed for potassium chloride, but they are expressed considerably weaker. Evaporation enthalpy and entropy are calculated for HfCl/sub 4/ and KCl monomers from their melted mixtures of various concentrations.

  16. Thermodynamics of HfCl4-KCl molten mixtures containing HfCl4 up to 33.3 mol. per cent

    International Nuclear Information System (INIS)

    Smirnov, M.V.; Salyulev, A.B.; Kudyakov, V.Ya.

    1980-01-01

    Based on measurements of saturated vapour pressure in components of melted mixtures of HfCl 4 -KCl, depending on temperature and concentration, calculated are the results of changes in activity coefficients of hafnium tetrachloride and potassium chloride on transition from diluted solutions, where the Henry law is met, to those concentrated where the law is disobeyed. Growth in the activity coefficient of HfCl 4 is due to dissociation of complex groups of HfCl 6 2- into complexes with a lesser number of ligands and decreasing relative binding energy of Hf 4+ -Cl - there. In this case, marked changes take place in partial enthalpy and entropy of hafnium tetrachloride mixing. Similar dependences are observed for potassium chloride, but they are expressed considerably weaker. Evaporation enthalpy and entropy are calculated for HfCl 4 and KCl monomers from their melted mixtures of various concentrations

  17. Preparation and study of the critical-mass-free plutonium ceramics with neutron poisons Hf, Gd and Li

    International Nuclear Information System (INIS)

    Timoefeeva, L.F.; Orlov, V.K.; Malyukov, E.E.; Molomin, V.I.; Zhmak, V.A.; Semova, E.A.; Shishkov, N.V.; Nadykto, B.A.

    2002-01-01

    Powder sintering was used to produce homogeneous type oxide ceramics of Pu with Hf, Gd and Li 6 . In all the ceramics, there is the number of neutron poison (Hf, Gd and Li) atoms per plutonium atom needed, according to the physical calculation, for them to be free of critical mass. PuO 2 stabilizers high-temperature modifications of cubic HfO 2 or hexagonal Gd 2 O 3 , however, at the ratio given by the physical calculation, the plutonium is insufficient for their full stabilization. Addition of yttrium oxide as an additive stabilizing the fcc phase of HfO 2 resulted in cubic solid solution (Pu, Hf, Y)O 2-x . Pu/Li/Hf and Pu/Li/Si ceramics produced by sintering of PuO 2 and compound Li 2 HfO 3 or 6 Li 4 SiO 4 powders is characterized with presence of two phases. The method of differential thermal analysis demonstrated the phase stability of (Pu-Hf, Pu-Gd, Pu-Li-Hf) oxide ceramics in the 20-1500degC temperature range. Ceramic (Pu/Li/Si) has several endothermal effects. Tests in boiling water solutions of various composition suggest that the specimens of Pu, Hf oxides and ternary oxides (Pu, Hf, Y)O 2 are less stable in weakly acidic media than in weakly alkaline medium and distilled water. The obtained results were used as a basis to estimate the assumed solid solution region boundaries for binary Hf, Pu and ternary Hf, Pu, Y oxides on the side of HfO 2 . (author)

  18. Mechanism of the transpassive dissolution and secondary passivation of chromium in sulphuric acid solutions

    International Nuclear Information System (INIS)

    Bojinov, M.; Betova, I.; Raicheff, R.; Fabricius, G.; Laitinen, T.; Saario, T.

    1998-01-01

    The transpassive dissolution and secondary passivation of Cr in 1..10 M H 2 SO 4 solutions were studied by a combination of different electrochemical methods. The steady-state polarization curves for transpassive dissolution exhibited a Tafel behaviour with a slope being independent on the acid concentration. Lower dissolution rates were measured for higher acid concentrations. Ring-disk measurements showed a release of both soluble Cr(VI) and Cr(III) during transpassivity. Impedance spectra were qualititatively similar in all acid concentrations, comprising one capacitive and two inductive semicircles. A kinetic model comprising two parallel transpassive dissolution paths was consistent with the experimental results. Typical passivation diagrams were observed for Cr in 10 M H 2 SO 4 , and a secondary passive state was established at higher potentials. The formation of the secondary passive film was confirmed by contact electric resistance (CER) measurements. A renewed version of the surface charge approach was consistent with the experimental results in the region of the secondary passivation. (orig.)

  19. Separation of Molybdenum from Acidic High-Phosphorus Tungsten Solution by Solvent Extraction

    Science.gov (United States)

    Li, Yongli; Zhao, Zhongwei

    2017-10-01

    A solvent-extraction process for deep separation of molybdenum from an acidic high-phosphate tungsten solution was developed using tributyl phosphate (TBP) as the extractant and hydrogen peroxide (H2O2) as a complexing agent. The common aqueous complexes of tungsten and molybdenum (PMoxW12-xO40 3-, x = 0-12) are depolymerized to {PO4[Mo(O)2(O-O)]4}3- and {PO4[W(O)2(O-O)]4}3- by H2O2. The former can be preferentially extracted by TBP. The extractant concentration, phase contact time, H2O2 dosage, and H2SO4 concentration were optimized. By employing 80% by volume TBP, O:A = 1:1, 1.0 mol/L H2SO4, 1.0 mol/L H3PO4, a contact time of 2 min, and a molar ratio of H2O2/(W + Mo) equal to 1.5, 60.2% molybdenum was extracted in a single stage, while limiting tungsten co-extraction to 3.2%. An extraction isotherm indicated that the raffinate could be reduced to <0.1 g/L Mo in six stages of continuous counter-current extraction.

  20. Metal extraction from Cetraria islandica (L. Ach. lichen using low pH solutions

    Directory of Open Access Journals (Sweden)

    ANA A. CUCULOVIC

    2008-04-01

    Full Text Available Extraction of metals (K, Al, Ca, Mg, Fe, Cu, Ba, Zn, Mn and Sr from dry Cetraria islandica (L. Ach. lichen was performed using solutions similar to acid rain (solution A – H2SO4–HNO3–(NH42SO4 and solution B – H2SO4–HNO3–(NH42SO4–NH4NO3. The pH values of these solutions were 2.00, 2.58, 2.87, 3.28, and 3.75. Five consecutive extractions were performed with each solution. In all solutions, the extracted metal content, except Cu and Ca, was the highest in the first extract. The highest percentage of the metals desorbed in the first extraction was obtained using solutions with low pH values, 2.00, 2.58, and 2.87. The lowest percentage in the first extraction was obtained using solutions with pH 3.28 and 3.75, indicating influence of the H+ ion on the extraction. According to the results obtained, the investigated metals form two groups. The first group includes K, Al, Ca, Mg, and Fe. They were extracted in each of the five extractions at each of the pH values. The second group includes Ba, Zn, Mn, Cu, and Sr, which were not all extracted at each pH value. The first group yielded three types of extraction curves when the logarithms of extracted metal amounts were plotted as a function of the number of successive extractions. These effects indicate that three different positions (centres of metal ion accumulation exist in the lichen (due to sorption, complex formation, or other processes present in the tissues.

  1. Metal-assisted chemical etching in HF/Na2S2O8 OR HF/KMnO4 produces porous silicon

    NARCIS (Netherlands)

    Hadjersi, T.; Gabouze, N.; Kooij, Ernst S.; Zinine, A.; Zinine, A.; Ababou, A.; Chergui, W.; Cheraga, H.; Belhousse, S.; Djeghri, A.

    2004-01-01

    A new metal-assisted chemical etching method using Na2S2O8 or KMnO4 as an oxidizing agent was proposed to form a porous silicon layer on a highly resistive p-type silicon. A thin layer of Ag or Pd is deposited on the Si(100) surface prior to immersion in a solution of HF and Na2S2O8 or HF and KMnO4.

  2. Green approach to corrosion inhibition of mild steel in two acidic solutions by the extract of Punica granatum peel and main constituents

    International Nuclear Information System (INIS)

    Behpour, M.; Ghoreishi, S.M.; Khayatkashani, M.; Soltani, N.

    2012-01-01

    Graphical abstract: Ellagic acid (EA) and tannic acid (TA) were studied as corrosion inhibitors. The electron density HOMO and LUMO of EA and TA were used to explain difference in behavior of them. Highlights: ► The extract of Punica granatum (PG) and their main constituent (ellagic acid (EA)) are found to be good inhibitors for the corrosion of mild steel in 1 M H 2 SO 4 and 2 M HCl. ► The electrochemical inhibitive mechanism is explained by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) results. ► The adsorption of ALLOX on mild steel surface was found to accord with the Temkin adsorption isotherm. ► The effect of temperature on the corrosion behavior of mild steel in 2 M HCl and 1 M H 2 SO 4 without and with the PG extract was studied. - Abstract: The effect of the extract of Punica granatum (PG) and their main constituents involve ellagic acid (EA) and tannic acid (TA), as mild steel corrosion inhibitor in 2 M HCl and 1 M H 2 SO 4 solutions was investigated by weight loss measurements. The results obtained from the weight loss measurements show that the inhibition efficiency of TA even in high concentration is very low. Thus, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) investigations were used for different concentrations of PG and EA and best concentration of TA. Potentiodynamic polarization curves indicated that PG and EA behave as mixed-type inhibitors. EIS measurements show an increase of the transfer resistance with increasing inhibitor concentration. The temperature effect on the corrosion behavior of steel without and with the PG extract was studied. The inhibition action of the extract was discussed in view of Langmuir adsorption isotherm.

  3. Suspended HfO2 photonic crystal slab on III-nitride/Si platform

    International Nuclear Information System (INIS)

    Wang, Yongjin; Feng, Jiao; Cao, Ziping; Zhu, Hongbo

    2014-01-01

    We present here the fabrication of suspended hafnium oxide (HfO 2 ) photonic crystal slab on a III-nitride/Si platform. The calculations are performed to model the suspended HfO 2 photonic crystal slab. Aluminum nitride (AlN) film is employed as the sacrificial layer to form air gap. Photonic crystal patterns are defined by electron beam lithography and transferred into HfO 2 film, and suspended HfO 2 photonic crystal slab is achieved on a III-nitride/Si platform through wet-etching of AlN layer in the alkaline solution. The method is promising for the fabrication of suspended HfO 2 nanostructures incorporating into a III-nitride/Si platform, or acting as the template for epitaxial growth of III-nitride materials. (orig.)

  4. Recovery of cyanide in gold leach waste solution by volatilization and absorption.

    Science.gov (United States)

    Gönen, N; Kabasakal, O S; Ozdil, G

    2004-09-10

    In this study, the effects of pH, time and temperature in regeneration of cyanide in the leaching waste solution of gold production from disseminated gold ore by cyanidation process were investigated and the optimum conditions, consumptions and cyanide recovery values were determined. The sample of waste solution containing 156 mg/l free CN- and 358 mg/l total CN-, that was obtained from Gümüşhane-Mastra/Turkey disseminated gold ores by cyanidation and carbon-in-pulp (CIP) process under laboratory conditions was used in the experiments. Acidification with H2SO4, volatilization of hydrogen cyanide (HCN) with air stripping and absorption of HCN in a basic solution stages were applied and under optimum conditions, 100% of free cyanide and 48% of complex cyanide and consequently 70% of the total cyanide in the liquid phase of gold leach effluent are recovered.

  5. The rotational excitation of HF by H

    Science.gov (United States)

    Desrousseaux, Benjamin; Lique, François

    2018-06-01

    The HF molecule is a key tracer of molecular hydrogen in diffuse interstellar medium (ISM). Accurate modelling of the HF abundance in such media requires one to model its excitation by both radiation and collisions. In diffuse ISM, the dominant collisional partners are atomic and molecular hydrogen. We report quantum time-independent calculations of collisional cross-sections and rate coefficients for the rotational excitation of HF by H. The reactive hydrogen exchange channels are taken into account in the scattering calculations. For the first time, HF-H rate coefficients are provided for temperature ranging from 10 to 500 K. The strongest collision-induced rotational HF transitions are those with Δj = 1, and the order of magnitude of the new HF-H rate coefficients is similar to that of the HF-H2 ones previously computed. As a first application, we simulate the excitation of HF by both H and H2 in typical diffuse ISM. We show that, depending on the rotational transition, hydrogen atoms increase or decrease the simulated excitation temperatures compared to collisional excitation only due to H2 molecules. Such results suggest that the new HF-H collisional data have to be used for properly modelling the abundance of HF in diffuse ISM.

  6. European coordination for coastal HF radar data in EMODnet Physics

    Science.gov (United States)

    Mader, Julien; Novellino, Antonio; Gorringe, Patrick; Griffa, Annalisa; Schulz-Stellenfleth, Johannes; Montero, Pedro; Montovani, Carlo; Ayensa, Garbi; Vila, Begoña; Rubio, Anna; Sagarminaga, Yolanda

    2015-04-01

    Historically, joint effort has been put on observing open ocean, organizing, homogenizing, sharing and reinforcing the impact of the acquired information based on one technology: ARGO with profilers Argo floats, EuroSites, ESONET-NoE, FixO3 for deep water platforms, Ferrybox for stations in ships of opportunities, and GROOM for the more recent gliders. This kind of networking creates synergies and makes easier the implementation of this source of data in the European Data exchange services like EMODnet, ROOSs portals, or any applied services in the Blue economy. One main targeted improvement in the second phase of EMODnet projects is the assembling of data along coastline. In that sense, further coordination is recommended between platform operators around a specific technology in order to make easier the implementation of the data in the platforms (4th EuroGOOS DATAMEQ WG). HF radar is today recognized internationally as a cost-effective solution to provide high spatial and temporal resolution current maps (depending on the instrument operation frequency, covering from a few kilometres offshore up to 200 km) that are needed for many applications for issues related to ocean surface drift or sea state characterization. Significant heterogeneity still exists in Europe concerning technological configurations, data processing, quality standards and data availability. This makes more difficult the development of a significant network for achieving the needed accessibility to HF Radar data for a pan European use. EuroGOOS took the initiative to lead and coordinate activities within the various observation platforms by establishing a number of Ocean Observing Task Teams such as HF-Radars. The purpose is to coordinate and join the technological, scientific and operational HF radar communities at European level. The goal of the group is on the harmonization of systems requirements, systems design, data quality, improvement and proof of the readiness and standardization of

  7. The magnetic hyperfine field in the 181Ta site in the Co2HfAl and Co2HfGa Heusler alloys

    International Nuclear Information System (INIS)

    Silva, R. da.

    1979-01-01

    The hyperfine magnetic fields at 181 Ta nuclei in Heusler alloys Co 2 HfZ (Z=Al, Ga) have been measured using the time differential perturbed gamma-gamma angular correlation (TDPAC) method. The hyperfine fields obtained from these measurements at the liquid nitrogen temperature are -189 and +- 150 kOersted for Co 2 HfAl and Co 2 HfGa, respectively. The concept that the hyperfine field at the Y site is similar to the solute fields in Fe, Co, Ni and Gd matrices is corroborated. We have verified that ratios H sub(hf) sub(Ta)/T sub(c) and H sub(hf) sub(Ta)μ sub(Co) in Co 2 HfZ compounds (Z=Al, Ga, Sn) do not depend on the nature of Z element. However a dependence in the value of observed field with the s-p element in Z site was noticed. We feel that the samples are not completely ordered cubic as observed by the quadrupole interaction measurements. The results are interpreted in terms of the Campbell-Blandin formalism, and it is shown that the spin polarization of conduction electrons at Hf and Ta have opposite signs. (Author) [pt

  8. Special Topics in HF Propagation

    Science.gov (United States)

    1979-11-01

    Capitaine de Frigate P.Italley Dr T.SJones Ing6nieur en Chef au CNET Physics Department 38 -40 rue du Gdn~ral Leclerc University of Leicester 9213 i1...fre’qiancý. A t’ctailcd discussion of HF reliability is giver in A companion paiper (MASLIN, N.M . 197(j)) the result tic ligs 4 atad % i-. sumniart-aed...conttoutt to determine if treie :s an additional zonal gqt.ient but wa shall ceo tto.., tnC companion Layttacings that it it, negliit.-tle. F:gur:!i 7A

  9. Atomic scale engineering of HfO2-based dielectrics for future DRAM applications

    International Nuclear Information System (INIS)

    Dudek, Piotr

    2011-01-01

    Modern dielectrics in combination with appropriate metal electrodes have a great potential to solve many difficulties associated with continuing miniaturization process in the microelectronic industry. One significant branch of microelectronics incorporates dynamic random access memory (DRAM) market. The DRAM devices scaled for over 35 years starting from 4 kb density to several Gb nowadays. The scaling process led to the dielectric material thickness reduction, resulting in higher leakage current density, and as a consequence higher power consumption. As a possible solution for this problem, alternative dielectric materials with improved electrical and material science parameters were intensively studied by many research groups. The higher dielectric constant allows the use of physically thicker layers with high capacitance but strongly reduced leakage current density. This work focused on deposition and characterization of thin insulating layers. The material engineering process was based on Si cleanroom compatible HfO 2 thin films deposited on TiN metal electrodes. A combined materials science and dielectric characterization study showed that Ba-added HfO 2 (BaHfO 3 ) films and Ti-added BaHfO 3 (BaHf 0.5 Ti 0.5 O 3 ) layers are promising candidates for future generation of state-of-the-art DRAMs. In especial a strong increase of the dielectric permittivity k was achieved for thin films of cubic BaHfO 3 (k∝38) and BaHf 0.5 Ti 0.5 O 3 (k∝90) with respect to monoclinic HfO 2 (k∝19). Meanwhile the CET values scaled down to 1 nm for BaHfO 3 and ∝0.8 nm for BaHf 0.5 Ti 0.5 O 3 with respect to HfO 2 (CET=1.5 nm). The Hf 4+ ions substitution in BaHfO 3 by Ti 4+ ions led to a significant decrease of thermal budget from 900 C for BaHfO 3 to 700 C for BaHf 0.5 Ti 0.5 O 3 . Future studies need to focus on the use of appropriate metal electrodes (high work function) and on film deposition process (homogeneity) for better current leakage control. (orig.)

  10. Atomic scale engineering of HfO{sub 2}-based dielectrics for future DRAM applications

    Energy Technology Data Exchange (ETDEWEB)

    Dudek, Piotr

    2011-02-14

    Modern dielectrics in combination with appropriate metal electrodes have a great potential to solve many difficulties associated with continuing miniaturization process in the microelectronic industry. One significant branch of microelectronics incorporates dynamic random access memory (DRAM) market. The DRAM devices scaled for over 35 years starting from 4 kb density to several Gb nowadays. The scaling process led to the dielectric material thickness reduction, resulting in higher leakage current density, and as a consequence higher power consumption. As a possible solution for this problem, alternative dielectric materials with improved electrical and material science parameters were intensively studied by many research groups. The higher dielectric constant allows the use of physically thicker layers with high capacitance but strongly reduced leakage current density. This work focused on deposition and characterization of thin insulating layers. The material engineering process was based on Si cleanroom compatible HfO{sub 2} thin films deposited on TiN metal electrodes. A combined materials science and dielectric characterization study showed that Ba-added HfO{sub 2} (BaHfO{sub 3}) films and Ti-added BaHfO{sub 3} (BaHf{sub 0.5}Ti{sub 0.5}O{sub 3}) layers are promising candidates for future generation of state-of-the-art DRAMs. In especial a strong increase of the dielectric permittivity k was achieved for thin films of cubic BaHfO{sub 3} (k{proportional_to}38) and BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} (k{proportional_to}90) with respect to monoclinic HfO{sub 2} (k{proportional_to}19). Meanwhile the CET values scaled down to 1 nm for BaHfO{sub 3} and {proportional_to}0.8 nm for BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} with respect to HfO{sub 2} (CET=1.5 nm). The Hf{sup 4+} ions substitution in BaHfO{sub 3} by Ti{sup 4+} ions led to a significant decrease of thermal budget from 900 C for BaHfO{sub 3} to 700 C for BaHf{sub 0.5}Ti{sub 0.5}O{sub 3}. Future studies need to focus

  11. Method of simultaneous continuous determination of transfer rates of iron and chromium into solution during Fe-Cr alloys dissolution

    International Nuclear Information System (INIS)

    Shirinov, T.I.; Florianovich, G.M.; Skuratnik, Ya.B.

    1978-01-01

    Radiometry method of simultaneous continuous registration of transfer rates of iron and chromium into solution from Fe-Cr alloys with various composition has been developed. Using gamma-spectrometer components of Fe-Cr alloys can be determined with high sensitivity in separate samples according to Fe 59 and Cr 51 radioactive labels, obtained by neutron activation. The above method is applied to estimate Fe and Cr transfer rates into H 2 SO 4 solution at the temperature of 50 deg from Fe - 28% Cr alloy during its active dissolution. It is established, that beginning with some seconds of alloy and solution contact, its components transfer into the solution in the same composition, as in the alloy. The method enables to determine Fe with the accuracy of up to 5% and Cr with that of up to 10%

  12. MO-HF-C alloy composition

    International Nuclear Information System (INIS)

    Whelan, E.P.; Kalns, E.

    1987-01-01

    This patent describes, as an article of manufacture, a cast ingot of a molybdenum-hafnium-carbon alloy consisting essentially by weight of about 0.6% to about 1% Hf, about 0.045% to about 0.08% C, and the balance essentially molybdenum. The amount of Hf and C present are substantially stoichiometric with respect to HfC and within about +-15% of stoichiometry. The ingot is characterized in that it has a substantially less tendency to crack compared to alloys containing Hf in excess of about 1% by weight and carbon in excess of 0.08% by weight, without substantial diminution in strength properties of the alloy

  13. Desorption of metals from Cetraria islandica (L. Ach. Lichen using solutions simulating acid rain

    Directory of Open Access Journals (Sweden)

    Čučulović Ana A.

    2014-01-01

    Full Text Available Desorption of metals K, Al, Ca, Mg, Fe, Ba, Zn, Mn, Cu and Sr from Cetraria islandica (L. with solutions whose composition was similar to that of acid rain, was investigated. Desorption of metals from the lichen was performed by five successive desorption processes. Solution mixtures containing H2SO4, HNO3 and H2SO4-HNO3 were used for desorption. Each solution had three different pH values: 4.61, 5.15 and 5.75, so that the desorptions were performed with nine different solutions successively five times, always using the same solution volume. The investigated metals can be divided into two groups. One group was comprised of K, Ca and Mg, which were desorbed in each of the five desorption processes at all pH values used. The second group included Al, Fe, Zn, Ba, Mn and Sr; these were not desorbed in each individual desorption and not at all pH values, whereas Cu was not desorbed at all under any circumstances. Using the logarithmic dependence of the metal content as a function of the desorption number, it was found that potassium builds two types of links and is connected with weaker links in lichen. Potassium is completely desorbed, 80% in the first desorption, and then gradually in the following desorptions. Other metals are linked with one weaker link (desorption 1-38% and with one very strong link (desorption below the metal detection limit. [Projekat Ministarstva nauke Republike Srbije, br. III43009 i br. ON 172019

  14. The Effectiveness of HCl and HF Cleaning of Si0.85Ge0.15 Surface

    International Nuclear Information System (INIS)

    Sun, Y

    2008-01-01

    The cleaning of Si 0.85 Ge 0.15 surfaces using HCl and HF solutions is studied using synchrotron radiation photoelectron spectroscopy. The HF solution is found to be effective in removing both the Si oxide and the Ge oxide while the HCl solution can only remove part of the Ge oxide. For samples treated with HF, four spectral components are needed to fit the Ge 3d photoemission spectra. One is the bulk component and the other three are attributed to the surface Ge atoms with mono-hydride, di-hydride and tri-hydride terminations, respectively

  15. Thermal expansion studies on HfO2-Gd2O3 system

    International Nuclear Information System (INIS)

    Panneerselvam, G.; Antony, M.P.; Nagarajan, K.

    2014-01-01

    A series of solid solutions containing GdO 1.5 in HfO 2 , (Hf 1-y Gd y ) O 2 (y = 0.15, 0.2, 0.3, 0.41 and 0.505) were prepared by solid state method. Structural characterization and computation of lattice parameter was carried out using room temperature X-ray diffraction measurements

  16. Removal of Calcium from Scheelite Leaching Solution by Addition of CaSO4 Inoculating Crystals

    Science.gov (United States)

    Liu, Wenting; Li, Yongli; Zeng, Dewen; Li, Jiangtao; Zhao, Zhongwei

    2018-04-01

    In this work, the solubility behaviors of gypsum and anhydrite in the H2SO4-H3PO4-H2O system were investigated over the temperature range T = 30-80°C, and the results showed that the solubility of anhydrite was considerably lower than that of gypsum. On the basis of the differential solubilities of gypsum and anhydrite, a method was developed to remove calcium from the scheelite leaching solution by adding anhydrite as an inoculating crystal. The effects of the reaction time, concentration of the CaSO4 inoculating crystals, and temperature were investigated. With an addition of CaSO4 inoculating crystals at a concentration of 60 g/L, the Ca2+ concentration of the scheelite leaching solution decreased to a low level of approximately 0.76 g/L after 10 h at 70°C.

  17. The kinetics of anodic dissolution of rhenium in aqueous electrolyte solutions

    International Nuclear Information System (INIS)

    Atanasyants, A.G.; Kornienko, V.A.

    1986-01-01

    The kinetics of anodic rhenium dissolution was investigated by means of potentiodynamic and potentiostatic polarization curves recorded at temperature from 293 to 333 K in different media (NaOH, KOH, NaCl, NaBr, HCl, H 2 SO 4 ) using the rotating disc technique. It is shown that the kinetics of anodic rhenium dissolution and effective activation energy depend not only on the composition and pH value of the solutions but also on the structure of the dissolving rhenium surface. The investigation of the anodic behaviour of the rhenium monocrystal revealed the existence of anisotropy of the monocrystal electrochemical properties. The experimental results point to an important role of adsorption processes in anodic rhenium dissolution. Rhenium dissolution proceeds with formation of intermediate surface adsorption complexes between the metal and the components of the solution

  18. Electric field gradients at 181Ta sites in HfOx

    International Nuclear Information System (INIS)

    Darriba, G.N.; Rodriguez, A.M.; Saitovitch, H.; Silva, P.R.J.; Pasquevich, A.F.

    2007-01-01

    In the present work we report preliminary results about the possibility to study properties of the order-disorder transition in HfO x solid solutions via the determination of the electric field gradient (EFG) at 181 Ta radioactive probes. Oxygen solution into the metal was achieved by arc melting stoichiometric amounts of metallic Hf and HfO 2 under argon atmosphere. Samples of HfO x with x=0.1 and 0.2 were prepared. Two types of samples were used for the perturbed angular correlation (PAC) experiments by doping alternatively with 181 Ta, by neutron irradiation, the metallic Hf or the hafnium oxide. The PAC results on both samples were identical, with disappearing hyperfine signals of the metal and the oxide, showing a complete diffusion of the probes independent of the way of doping. The PAC signal of the HfO x solid solution consisted in a wide distribution of EFGs due to the oxygen disorder. This scheme held even after long thermal treatments at high temperature (several days at 1273K). Annealing treatments at moderate temperature (600K) were also made. In these cases the samples were cooling at a very low rate. These results, together with those obtained by measuring samples below and above the order temperature are reported

  19. Development of HF-systems for electron storage systems

    International Nuclear Information System (INIS)

    Androsov, V.P.; Karnaukhov, I.M.; Popkov, Yu.P.; Reva, S.N.; Telegin, Yu.N.

    1999-01-01

    Development of HF systems for electron storages is described. Its final task is construction of 100 kW HF station at 699,3 MHz frequency consisting from low-power HF system, klystron amplifier, wave line for HF power transmission and accelerating section. Functional parameters of HF station are given

  20. DORMANCY BREAKING OF OIL PALM SEED TENERA VARIETY BY SOAKING FOR A CERTAIN LENGTH OF TIME IN THE SULFURIC ACID SOLUTION

    Directory of Open Access Journals (Sweden)

    WAYAN SUENA

    2012-11-01

    Full Text Available The experiment aimed to know the effect of length of soaked time in sulfuric acid (H2SO4 solution to the dormancy breaking upon the oil palm seeds. The experiment show that soaking seeds for 12 and 10 minutes in the acid solution resulted dormancy breaking were reached after 61.3 days, while soaking seed for 2 minutes in the same solution breaking of dormancy was reached after 73.5 days. By soaked oil palm seeds in sulfuric acid solution gave highest germination percentage (80%, peak value of germination was 0.77%/day, by an average of 0.73%/day. So that, by soaked oil palm seed in sulfuric acid solution for 12 minutes was able to increase vigor, viability, rate of germination and growth uniformity.

  1. Positron annihilation studies in Hf doped YBCO

    International Nuclear Information System (INIS)

    Gopalan, P.; Priya, E.R.; Premila, M.; Sundar, C.S.; Gopinathan, K.P.

    1992-01-01

    The variation of positron lifetime and oxygen stoichiometry as a function of quench temperature has been measured in undoped and 0.5at%, 0.75at%, and 1.0 at% Hf doped YBCO. In both the undoped and Hf doped samples, the lifetime decreases and the oxygen content increases as the quench temperature is lowered from 900degC to 300degC. The lifetime in the tetragonal phase (900degC) decreases with the increase in Hf content, whereas in the orthorhombic phase (450degC) it increases. The difference in lifetime between the tetragonal and orthorhombic phases decreases with the increase in the Hf content. These trends are discussed in terms of the influence of Hf doping on the oxygen content and the positron density distribution in YBCO

  2. Study on the adducts formation of Zr and Hf chelates

    International Nuclear Information System (INIS)

    Ree, Chin Taik; Jung, Young Sam; Park, Jun Kown

    1986-01-01

    The synergistic effect observed in Zr(IV) and Hf(IV) extraction from strong perchloric acid solutions by the mixtures of 2-Thenoyltri-fluoroacetone(TTA) and Octanols is shown to be caused by the formation of a mixed complex, M(TTA) 3 XS (M=Zr(IV), HF(IV), X=ClO 4 - , S=Octanol). One of the four TTA molecules coordinated at lower HClO 4 concentration to the metal as bidendate ligand seems to be changed to monodendate due to increasing HClO 4 concentration. The monodenate TTA ligand leaves the coordination site, finally, due to the activity of perchlorate at higher concentration and the additional coordination of an Octanol molecule seems to be allowed to the vaccant site which shows the synergistic extraction phenomena. (Author)

  3. A novel process for preparation of titanium dioxide from Ti-bearing electric furnace slag: NH4HF2-HF leaching and hydrolyzing process.

    Science.gov (United States)

    Zheng, Fuqiang; Guo, Yufeng; Qiu, Guanzhou; Chen, Feng; Wang, Shuai; Sui, Yulei; Jiang, Tao; Yang, Lingzhi

    2018-02-15

    A novel process to prepare titanium dioxide from Ti-bearing electric furnace slag by NH 4 HF 2 -HF leaching and hydrolyzing process has been developed. In this present study, the effects of [NH 4 + ]/[F] mXolar ratio, leaching temperature, [F] concentration, liquid/solid mass ratio, leaching time on the Ti extraction, and the phase transformations have been investigated to reveal the leaching mechanism of Ti-bearing electric furnace slag in NH 4 HF 2 -HF solution. In the NH 4 HF 2 -HF leaching process, the MgTi 2 O 5 and Al 2 TiO 5 are converted to TiF 6 2- and Mg-Al-bearing precipitate. Ti extraction rate reached 98.84% under the optimal conditions. In addition, 98.25% iron ions can be removed in the presence of NaCl prior to hydrolysis process. The effects of pH and temperature on the selective hydrolysis of TiF 6 2- during hydrolysis process were also studied. In the hydrolysis process, the TiF 6 2- is converted to (NH 4 ) 2 TiOF 4 . By calcination, high grade TiO 2 powder with its purity of 99.88% was obtained, using which the products, well crystallized anatase and rutile, were obtained through roasting at 800°C and 1000°C, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Aspects of HF radio propagation

    Directory of Open Access Journals (Sweden)

    Stephane Saillant

    2009-06-01

    Full Text Available

    radio systems. From the point of view Working Group 2 of the COST 296 Action, interest lies with effects associated

    with propagation via the ionosphere of signals within the HF band. Several aspects are covered in this paper:

    a The directions of arrival and times of flight of signals received over a path oriented along the trough have

    been examined and several types of propagation effects identified. Of particular note, combining the HF observations

    with satellite measurements has identified the presence of irregularities within the floor of the trough that

    result in propagation displaced from the great circle direction. An understanding of the propagation effects that

    result in deviations of the signal path from the great circle direction are of particular relevance to the operation

    of HF radiolocation systems.

    b Inclusion of the results from the above mentioned measurements into a propagation model of the northerly

    ionosphere (i.e. those regions of the ionosphere located poleward of, and including, the mid-latitude trough

    and the use of this model to predict the coverage expected from transmitters where the signals impinge on the

    northerly ionosphere

  5. Deposition of Coating to Protect Waste Water Reservoir in Acidic Solution by Arc Thermal Spray Process

    Directory of Open Access Journals (Sweden)

    Han-Seung Lee

    2018-01-01

    Full Text Available The corrosion characteristics of 304 stainless steel (SS and titanium (Ti coatings deposited by the arc thermal spray process in pH 4 solution were assessed. The Ti-sprayed coating exhibits uniform, less porous, and adherent coating morphology compared to the SS-sprayed coating. The electrochemical study, that is, electrochemical impedance spectroscopy (EIS, revealed that as exposure periods to solution were increased, the polarization resistance (Rp decreased and the charge transfer resistance (Rct increased owing to corrosion of the metallic surface and simultaneously at the same time the deposition of oxide films/corrosion on the SS-sprayed surface, while Ti coating transformed unstable oxides into the stable phase. Potentiodynamic studies confirmed that both sprayed coatings exhibited passive tendency attributed due to the deposition of corrosion products on SS samples, whereas the Ti-sprayed sample formed passive oxide films. The Ti coating reduced the corrosion rate by more than six times compared to the SS coating after 312 h of exposure to sulfuric acid- (H2SO4- contaminated water solution, that is, pH 4. Scanning electron microscope (SEM results confirmed the uniform and globular morphology of the passive film on the Ti coating resulting in reduced corrosion. On the other hand, the corrosion products formed on SS-sprayed coating exhibit micropores with a net-like microstructure. X-ray diffraction (XRD revealed the presence of the composite oxide film on Ti-sprayed samples and lepidocrocite (γ-FeOOH on the SS-coated surface. The transformation of TiO and Ti3O into TiO2 (rutile and anatase and Ti3O5 after 312 h of exposure to H2SO4 acid reveals the improved corrosion resistance properties of Ti-sprayed coating.

  6. Microhardness evaluation alloys Hf-Si-B; Avaliacao de microdureza de ligas Hf-Si-B

    Energy Technology Data Exchange (ETDEWEB)

    Gigolotti, Joao Carlos Janio; Costa, Eliane Fernandes Brasil [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Nunes, Carlos Angelo; Rocha, Elisa Gombio; Coelho, Gilberto Carvalho, E-mail: carlosjanio@uol.com.br, E-mail: eliane-costabrasi@hotmail.com, E-mail: cnunes@demar.eel.usp.br, E-mail: elisarocha@alunos.eel.usp.br, E-mail: coelho@demar.eel.usp.br [Universidade de Sao Paulo (USP), Lorena, SP (Brazil)

    2014-08-15

    The technological advance has generated increasing demand for materials that can be used under high temperature, what includes intermetallic MR-Si-B (MR = refractory metal) alloys with multiphase structures, that can also be applied in oxide environments. Thus, this work had for objective the micro hardness study of the Hf-Si-B system alloys, heat treated at 1600 deg C, in the Hf rich region. Hf-Si-B alloys had been produced with blades of Hf (min. 99.8%), Si (min. 99.998%) and B (min. 99.5%), in the voltaic arc furnace and heat treated at 1600 deg C under argon atmosphere. The relationship of the phases had been previously identified by X-ray diffraction and contrast in backscattered electron imaging mode. The alloys had their hardness analyzed by method Vickers (micro hardness) with load of 0.05 kgf and 0.2 kgf and application time of 20 s. The results, obtained from the arithmetic mean of measurements for each alloy on the heterogeneous region, showed a mean hardness of 11.08 GPA, with small coefficient of variation of 3.8%. The borides HfB2 (19.34 GPa) e HfB - 11.76 GPa, showed the hardness higher than the silicides Hf2Si (8.57 GPa), Hf5Si3 (9.63 GPa), Hf3Si2 (11.66 GPa), Hf5Si4 (10.00 GPa), HfSi (10.02 GPa) e HfSi2 (8.61 GPa). (author)

  7. Heavy ion studies with CMS HF calorimeter

    International Nuclear Information System (INIS)

    Damgov, I.; Genchev, V.; Kolosov, V.A.; Lokhtin, I.P.; Petrushanko, S.V.; Sarycheva, L.I.; Teplov, S.Yu.; Shmatov, S.V.; Zarubin, P.I.

    2001-01-01

    The capability of the very forward (HF) calorimeter of the CMS detector at LHC to be applied to specific studies with heavy ion beams is discussed. The simulated responses of the HF calorimeter to nucleus-nucleus collisions are used for the analysis of different problems: reconstruction of the total energy flow in the forward rapidity region, accuracy of determination of the impact parameter of collision, study of fluctuations of the hadronic-to-electromagnetic energy ratio, fast inelastic event selection

  8. HF treatment effect for carbon deposition on silicon (111) by DC sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Aji, A. S., E-mail: aji.ravazes70@gmail.com; Darma, Y., E-mail: aji.ravazes70@gmail.com [Quantum Semiconductor and Devices Lab., Physics of Material Electronics Research Division, Department of Physics, Institut Teknologi Bandung (Indonesia)

    2014-03-24

    Surface modifications of Si (111) substrate by HF solution for thin film carbon deposition have been systematically studied. Thin film carbon on Si (111) has been deposited using DC Unbalanced Magnetron Sputtering with carbon pellet doped by 5% Fe as the target. EDAX characterization confirmed that the carbon fraction on Si substrate much higher by dipping a clean Si substrate by HF solution before sputtering process in comparison with carbon fraction on Si substrate just after conventional RCA. Moreover, SEM and AFM images show the uniform thin film carbon on Si with HF treatment, in contrast to the Si without HF solution treatment. These experimental results suggest that HF treatment of Si surface provide Si-H bonds on top Si surface that useful to enhance the carbon deposition during sputtering process. Furthermore, we investigate the thermal stability of thin film carbon on Si by thermal annealing process up to 900 °C. Atomic arrangements during annealing process were characterized by Raman spectroscopy. Raman spectra indicate that thin film carbon on Si is remaining unchanged until 600 °C and carbon atoms start to diffuse toward Si substrate after annealing at 900 °C.

  9. Chemical states and electronic structure of a HfO(-2)/Ge(001) interface

    International Nuclear Information System (INIS)

    Seo, Kang-ill; McIntyre, Paul C.; Stanford U., Materials Sci. Dept.; Sun, Shiyu; Lee, Dong-Ick; Pianetta, Piero; SLAC, SSRL; Saraswat, Krishna C.; Stanford U., Elect. Eng. Dept.

    2005-01-01

    We report the chemical bonding structure and valence band alignment at the HfO 2 /Ge (001) interface by systematically probing various core level spectra as well as valence band spectra using soft x-rays at the Stanford Synchrotron Radiation Laboratory. We investigated the chemical bonding changes as a function of depth through the dielectric stack by taking a series of synchrotron photoemission spectra as we etched through the HfO 2 film using a dilute HF-solution. We found that a very non-stoichiometric GeO x layer exists at the HfO 2 /Ge interface. The valence band spectra near the Fermi level in each different film structure were carefully analyzed, and as a result, the valence band offset between Ge and GeO x was determined to be ΔE v (Ge-GeO x ) = 2.2 ± 0.15 eV, and that between Ge and HfO 2 , ΔE v (Ge-HfO 2 ) = 2.7 ± 0.15 eV

  10. Determination of the rate of HF hydration and the effects of HF on moisture condensation

    International Nuclear Information System (INIS)

    McCulla, W.H.

    1982-01-01

    There were four basic questions addressed in this report that relate to the HF interaction in the environment. As to whether HF hydrates in the vapor phase and what the rate of that hydration is, there seems ample evidence that HF hydrates readily in the vapor phase and the rate of that hydration is very fast, i.e., dHF/dt greater than or equal to 25 torr sec -1 . Concerning under what conditions condensation of the hydrate will occur and whether a third body is required for condensation, it was found that HF does effect the dew point or condensation of water and data was presented indicating the extent of that effect. It was also determined that condensation will occur without a third body present. Thus, in attempting to model an HF release for the Safety Analysis Report the hydration of HF and the subsequent heat released may be treated as occurring instantaneously; but the ultimate disposition of the HF will be strongly dependent upon the environmental conditions at the time of the release

  11. Determination of the rate of HF hydration and the effects of HF on moisture condensation

    Energy Technology Data Exchange (ETDEWEB)

    McCulla, W H

    1982-04-30

    There were four basic questions addressed in this report that relate to the HF interaction in the environment. As to whether HF hydrates in the vapor phase and what the rate of that hydration is, there seems ample evidence that HF hydrates readily in the vapor phase and the rate of that hydration is very fast, i.e., dHF/dt greater than or equal to 25 torr sec/sup -1/. Concerning under what conditions condensation of the hydrate will occur and whether a third body is required for condensation, it was found that HF does effect the dew point or condensation of water and data was presented indicating the extent of that effect. It was also determined that condensation will occur without a third body present. Thus, in attempting to model an HF release for the Safety Analysis Report the hydration of HF and the subsequent heat released may be treated as occurring instantaneously; but the ultimate disposition of the HF will be strongly dependent upon the environmental conditions at the time of the release.

  12. Densities and apparent molar volumes of atmospherically important electrolyte solutions. 2. The systems H(+)-HSO4(-)-SO4(2-)-H2O from 0 to 3 mol kg(-1) as a function of temperature and H(+)-NH4(+)-HSO4(-)-SO4)2-)-H2O from 0 to 6 mol kg(-1) at 25 °C using a Pitzer ion interaction model, and NH4HSO4-H2O and (NH4)3H(SO4)2-H2O over the entire concentration range.

    Science.gov (United States)

    Clegg, S L; Wexler, A S

    2011-04-21

    A Pitzer ion interaction model has been applied to the systems H(2)SO(4)-H(2)O (0-3 mol kg(-1), 0-55 °C) and H(2)SO(4)-(NH(4))(2)SO(4)-H(2)O (0-6 mol kg(-1), 25 °C) for the calculation of apparent molar volume and density. The dissociation reaction HSO(4)(-)((aq)) ↔ H(+)((aq)) + SO(4)(2-)((aq)) is treated explicitly. Apparent molar volumes of the SO(4)(2-) ion at infinite dilution were obtained from part 1 of this work, (1) and the value for the bisulfate ion was determined in this study from 0 to 55 °C. In dilute solutions of both systems, the change in the degree of dissociation of the HSO(4)(-) ion with concentration results in much larger variations of the apparent molar volumes of the solutes than for conventional strong (fully dissociated) electrolytes. Densities and apparent molar volumes are tabulated. Apparent molar volumes calculated using the model are combined with other data for the solutes NH(4)HSO(4) and (NH(4))(3)H(SO(4))(2) at 25 °C to obtain apparent molar volumes and densities over the entire concentration range (including solutions supersaturated with respect to the salts).

  13. High-K rotational bands in {sup 174}Hf and {sup 175}Hf

    Energy Technology Data Exchange (ETDEWEB)

    Gjoerup, N L; Sletten, G [The Niels Bohr Institute, Roskilbe (Denmark); Walker, P M [Surrey Univ., Guildford (United Kingdom). Dept. of Physics; Bentley, M A [Daresbury Lab. (United Kingdom); Cullen, D M; Sharpey-Schafer, J F; Fallon, P; Smith, G [Liverpool Univ. (United Kingdom). Oliver Lodge Lab.

    1992-08-01

    High sensitivity experiments with {sup 48}Ca, {sup 18}O and {sup 9}Be induced reactions using the ESSA-30, TESSA-3 and NORDBALL arrays have provided extensive new information on the high spin level structures of {sup 174}Hf and {sup 175}Hf. During the series of experiments, several new bands have been found and most known bands have been extended considerably. Spin and excitation energy ranges for {sup 174}Hf are now {approx} 35 {Dirac_h} and {approx} 13 MeV, respectively, and for {sup 175}Hf ranges are {approx} 30 {Dirac_h} and {approx} 7 MeV. respectively. Several new high-K structures have been found in {sup 174}Hf and the structure of these and the already known high-K bands in both nuclei together with the new Tilted Axis Cranking approach might explain the small K-hindrances observed for K-isomers in this region. (author). 8 refs., 2 figs.

  14. Thermal evolution of CaO-doped HfO{sub 2} films and powders

    Energy Technology Data Exchange (ETDEWEB)

    Barolin, S A; Sanctis, O A de [Lab. Materiales Ceramicos, FCEIyA, Universidad Nacional de Rosario, IFIR-CONICET (Argentina); Caracoche, M C; Martinez, J A; Taylor, M A; Pasquevich, A F [Departamento de Fisica, FCE, Universidad Nacional de La Plata, IFLP-CONICET (Argentina); Rivas, P C, E-mail: oski@fceia.unr.edu.a [Facultad de Ciencias Agronomicas y Forestales, Universidad Nacional de La Plata, IFLP (Argentina)

    2009-05-01

    Solid solutions of ZrO2 and HfO2 are potential electrolyte materials for intermediate-temperature SOFC because both are oxygen-ion conductors. The main challenge for these compounds is to reduce the relatively high value of the activation energies vacancies diffusion, which is influenced by several factors. In this work the thermal evolution of CaO-HfO{sub 2} materials have been investigated. (CaO)y-Hf(1-y)O(2-y) (y = 0.06, 0.14 y 0.2) coatings and powders were synthesized by chemical solution deposition (CSD). Films were deposited onto alumina substrates by Dip Coating technique, the burning of organic waste was carried out at 500 deg. C under normal atmosphere and then the films were thermally treated at intervals of temperature rising to a maximum temperature of 1250 deg. C. By means Glazing Incidence X-ray Diffraction (rho-2theta configuration) the phases were studied in the annealed films. On the other hand, the thermal evolution and crystallization process of powders were analyzed in-situ by HT-XRD. The phenomena crystallization occurred in films and powders were analyzed. The activation energies of diffusion of oxygen vacancies of HfO2-14 mole% CaO and HfO2-20 mole% CaO films were measured from the thermal evolution of the relaxation constant measured by Perturbed Angular Correlation Technique.

  15. Recovery of manganese and zinc from spent Zn-C cell powder: Experimental design of leaching by sulfuric acid solution containing glucose.

    Science.gov (United States)

    Biswas, Ranjit K; Karmakar, Aneek K; Kumar, Sree L

    2016-05-01

    The spent Zn-C cell powder, containing ZnMn2O4, ZnO, MnO(OH) and possibly Mn2O3 and Mn3O4, can be leached by a sulfuric acid solution mixed with some glucose. The leaching is found to be dependent on solid to liquid (S/L) ratio, amount of glucose, concentration of sulfuric acid solution, time and pulp agitation speed. For 5g powder (S), 1h leaching time and 300rpm pulp agitation speed, two-level four-factor (2(4)) experimental designs have been carried out to derive models for extraction of both Mn(II) and Zn(II). Amount of glucose (G, g), concentration of H2SO4 solution (C, mol/L), volume of H2SO4 solution as leachant (L, mL) and leaching temperature (T, °C) are considered as factors (variables). The model in both cases consists of mean, factor effects and interaction effects. The four-factor interaction effect is observed in neither of the cases. Some two-factor and three-factor effects are found to have produced positive or negative contributions to dissolution percentage in both cases. The models are examined for comparison with experimental results with good fits and also used for optimization of factors. At optimized condition (G=0.50g, C=2mol/L, L=250mL and T=100°C), an aliquot of 5g powder in 1h and at 300rpm produces a solution containing (7.08±0.10)g/L Mn(II) and (2.20±0.06)g/L Zn(II) corresponding to almost 100% extraction of both metal ions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Effect of the hydrogen charging of AISI 316 stainless steel from solutions containing As2 O3

    International Nuclear Information System (INIS)

    Brito, S.D. de.

    1973-01-01

    The hydrogen charging of AISI 316 stainless steel has turned unstable the austenitic structure which partially decomposes into two phases: ε (hexagonal close packed) and α ' (body centered cubic). A 1 N H 2 SO 4 solution was used as electrolyte, with varying concentrations of As 2 O 3 (0, 1, 5 and 100 mg/l) for a single constant applied current density (i o = 0,22 A/cm 2 ). It was observed that a smaller austenitic grain as well as a larger hydrogen charging time, improve the phase transformation. It was established that the order in which the transformation products of the austenite appear through hydrogen charging follows the sequence: Y → Y-bar + ε → Y + ε + α ', although there is still some doubt about the equivalent transformation order by plastic deformation. (author)

  17. Electrocatalytic reduction of dioxygen by cobalt porphyrin-modified glassy carbon electrode with single-walled carbon nanotubes and nafion in aqueous solutions

    International Nuclear Information System (INIS)

    Choi, Ayoung; Jeong, Haesang; Kim, Songmi; Jo, Suhee; Jeon, Seungwon

    2008-01-01

    Cobalt porphyrin (CoP)-modified glassy carbon electrode (GCE) with single-walled carbon nanotubes (SWNTs) and Nafion demonstrated a higher electrocatalytic activity for the reduction of dioxygen in 0.1 M H 2 SO 4 solution. Cyclic and hydrodynamic voltammetry at the CoP-SWNTs/GCE-modified electrodes in O 2 -saturated aqueous solutions was used to study the electrocatalytic pathway. Compared with the CoP/GCE-modified electrodes, the reduction potential of dioxygen at the CoP-SWNTs/GCE-modified electrodes was shifted to the positive direction and the limiting current was greatly increased. Especially, the Co(TMPP)-SWNTs/GCE-modified electrode was catalyzed effectively by the 4e - reduction of dioxygen to water, because hydrodynamic voltammetry revealed the transference of approximately four electrons for dioxygen reduction and the minimal generation of hydrogen peroxide in the process of dioxygen reduction

  18. Comparison of HfCl4, HfI4, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO2 films deposited by ALD: A DFT study

    Science.gov (United States)

    Cortez-Valadez, M.; Fierro, C.; Farias-Mancilla, J. R.; Vargas-Ortiz, A.; Flores-Acosta, M.; Ramírez-Bon, R.; Enriquez-Carrejo, J. L.; Soubervielle-Montalvo, C.; Mani-Gonzalez, P. G.

    2016-06-01

    The final structure of HfO2 films grown by atomic layer deposition (ALD) after reaction with OH- ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl4 (hafnium tetrachloride), HfI4 (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO-H was studied employing the B3LYP (Becke 3-parameter, Lee-Yang-Parr) hybrid functional and the PBE (Perdew-Burke-Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

  19. Intergranular corrosion of 13Cr and 17Cr martensitic stainless steels in accelerated corrosive solution and high-temperature, high-purity water

    International Nuclear Information System (INIS)

    Ozaki, Toshinori; Ishikawa, Yuichi

    1988-01-01

    Intergranular corrosion behavior of 13Cr and 17Cr martensitic stainless steels was studied by electrochemical and immersing corrosion tests. Effects of the mEtallurgical and environmental conditions on the intergranular corrosion of various tempered steels were examined by the following tests and discussed. (a) Anodic polarization measurement and electrolytical etching test in 0.5 kmol/m 3 H 2 SO 4 solution at 293 K. (b) Immersion corrosion test in 0.88 kmol/m 3 HNO 3 solution at 293 K. (c) Long-time immersion test for specimens with a crevice in a high purity water at 473 K∼561 K. It was found from the anodic polarization curves in 0.5 kmol/m 3 H 2 SO 4 solution-at 293 K that the steels tempered at 773∼873 K had susceptibility to intergranular corrosion in the potential region indicating a second current maximum (around-0.1 V. vs. SCE). But the steel became passive in the more noble potential region than the second current peak potential, while in the less noble potential region general corrosion occurred independent of its microstructure. The intergranular corrosion occurred due to the localized dissolution along the pre-austenitic grain boundary and the martensitic lath boundary. It could be explained by the same dissolution model of the chromium depleted zone as proposed for the intergranular corrosion of austenitic and ferritic stainless steels. The intergranular corrosion occurred entirely at the free surface in 0.88 kmol/m 3 HNO 3 solution, while in the high temperature and high purity water only the entrance of the crevice corroded. It was also suggested that this intergranular corrosion might serve as the initiation site for stress corrosion cracking of the martensitic stainless steel. (author)

  20. Low lying magnetic dipole strength distribution in 176Hf

    International Nuclear Information System (INIS)

    Kuliev, A. A.; Ertugral, F.; Yakut, H.; Bektasoglu, M.; Guliyev, E.

    2006-01-01

    In this study the scissors mode 1 + states are systematically investigated within the rotational invariant Quasiparticle Random Phase Approximation (QRPA) for 1 76Hf isotopes. We consider the 1 + vibrations generated by the isovector spin-spin interactions and the isoscalar (h 0 ) and isovector (h 1 ) quadrupole type separable forces restoring the broken symmetry by a deformed mean field. It has been shown that restoration of the broken rotational symmetry of the Hamiltonian essentially decreases the B(M1) value of the low lying 1 + states and increases the collectivization of the scissors mode excitations in the spectroscopic energy region. Agreement between the calculated mean excitation energies as well as the summed B(M1) value of the scissors mode excitations and the available experimental data of 1 76Hf is rather good. For instance, distributions of the calculated B(M1) transition strengths in the 1 76 Hf isotopes with respect to K π =1 + excitations is represented in Figure. Thus, we see that the models which use the Hamiltonian with broken rotational symmetry strongly overestimate the M1 strength at low energy. These results indicate an importance of the models which are free from the low-energy spurious states. The marked differences between the results for 1 + states, calculated in rotational invariant (RI) and non-rotational invariant (NRI) model indicate the importance of the approaches which are free from spurious low-energy solutions. A separation of the rotational state from the 1 + states changes somewhat the distribution of the B(M1) strength in the spectroscopic energy region and increases the fragmentation of the scissors mode 1 + excitations in agreement with the experimental data

  1. Searching triaxial superdeformation in 175Hf

    International Nuclear Information System (INIS)

    Li Xiaowei; Zhejiang Normal Univ., Jinhua; Yu Shaoying; Zhejiang Normal Univ., Jinhua; Chinese Academy of Sciences, Beijing; Shen Caiwan; National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou; Chen Yongshou; Chinese Academy of Sciences, Beijing; National Laboratory of Heavy Ion Accelerator of Lanzhou

    2006-01-01

    A two-dimensional Total Routhian Surface (TRS) calculation is carried out in order to ascertain if there is triaxial superdeformation in 175 Hf. A five quasi-particle configuration is chosen in the calculation. Unfortunately, the TRS minimum does not show up in the total potential energy surface. (authors)

  2. Ferromagnetic characteristics of HfFe2

    International Nuclear Information System (INIS)

    Novakovic, N.; Belosevic-Cavor, J.; Cekic, B.; Manasijevic, M.; Milosevic, Z. . E-mail address of correspoding author: novnik@rt270.vin.bg.ac.yu; Novakovic, N.)

    2003-01-01

    The magnetic hyperfine fields at 181 Ta ion-probe sites in the HfFe 2 polycrystalline binary compound were measured using the time-differential perturbed angular correlation (TDPAC) method. Measurements were performed in the absence of polarizing external magnetic field, at room temperature. The existence of two different structures, dominant cubic MgCu 2 -type and hexagonal MgZn 2 -type in our HfFe 2 sample was refined. Both structures are ferromagnetic with Curie temperatures, which differ significantly (588 K for MgCu 2 and 427 K for MgZn 2 ). The corresponding values of hyperfine fields are H hf 13.8±0.1 T for MgCu 2 -type structure and H hf = 8.0±0.2 T for MgZn 2 -type structure. Calculations using LAPW-Wien 97 program package are in progress and preliminary results are in good agreement with experiment. The analysis includes qualitative explanation of the exchange interactions mechanism between magnetic dipole moment of the observed 181 Ta ion-probe and magnetic dipole moments of the nearest neighbours on the corresponding coordination polyhedra. All these results will be published recently. (author)

  3. Statistical gamma transitions in {sup 174}Hf

    Energy Technology Data Exchange (ETDEWEB)

    Farris, L P; Cizewski, J A; Brinkman, M J; Henry, R G; Lee, C S [Rutgers--the State Univ., New Brunswick, NJ (United States); Khoo, T L; Janssens, R V.F.; Moore, E F; Carpenter, M P; Ahmad, I; Lauritsen, T [Argonne National Lab., IL (United States); Kolata, J J; Beard, K B; Ye, B; Garg, U [Notre Dame Univ., IN (United States); Kaplan, M S; Saladin, J X; Winchell, D [Pittsburgh Univ., PA (United States)

    1992-08-01

    The statistical spectrum extracted from the {sup 172}Yb({alpha},2n){sup 174}Hf reaction was fit with Monte Carlo simulations using a modified GDR E1 strength function and several formulations of the level density. (author). 15 refs., 1 tab., 3 figs.

  4. Study of plutonium sorption in aluminia column in the system HNO3-HF

    International Nuclear Information System (INIS)

    Araujo, J.A. de.

    1977-01-01

    The column chromatographic method using alumina has been applied successfully to study the sorption-desorption behavior of plutonium traces in HNO 3 -HF and HNO 3 -HF-UO 2 (NO 3 ) 2 systems, aiming to elaborate a process for recovering plutonium traces from reprocessing wastes, mainly in existing solutions where uranium is presented in macro quantities. Basically, the method consists in the sorption of plutonium by percolating a solution containing HNO 3 (0,1 to 0,8M) or uranyl nitrate (1-50 gU/l) and HF(0,1 to 0,3M) through an Al 2 O 3 collumn. The plutonium is fixed on Al 2 O 3 whereas the uranyl ions is collected in the efluent. The adsorption of Pu-III, Pu-IV and Pu-VI in the presence of HF was determined and Pu-IV can be almost completely sorbed. The Pu-IV is eluted by reduction to Pu-III in the column using 3 M HNO 3 -0,005M FeSO 4 at 50 0 C as elutrient. This method is very simple and can be applied for separation and purification of plutonium (traces) from uranyl nitrate or others coming solutions from wet chemistry of irradiated fuels [pt

  5. Calculation of the local power peaking near WWER-440 control assemblies with Hf plates

    International Nuclear Information System (INIS)

    Hegyi, Gy.; Hordosy, G.; Kereszturi, A.; Maraszy, Cs.; Temesvari, E.

    2003-01-01

    The original coupler design of the WWER-440 assemblies had the following well known deficiency: The relatively large amount of water in the coupler between the absorber and fuel port of the control assembly can cause undesirably sharp power peaking in the fuel rods next to the coupler. The power peaking can be especially high after control rod withdrawal when the coupler reached low burnup level region of the adjacent assembly. The modernized coupler design overcomes the original problem by applying a thin Hf plate in the critical region. The very complicated structure of the coupler requires the verification of the core design methods by high precision 3D Monte Carlo calculations. The paper presents an MCNP reference calculation on the control rod coupler benchmark with Hf absorber plates. The benchmark solution with the KARATE-440 code system is also presented. The need for treating the Hf burnout in the reflector region is investigated (Authors)

  6. Corrosion Characteristics of Ti-29Nb-xHf Ternary Alloy for Biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Pak, Sun Young; Choi, Han Chul [Chosun Univ., Kwangju (Korea, Republic of)

    2015-12-15

    The Cp-Ti and Ti-6Al-4V alloys were widely used for dental materials due to their mechanical properties and good corrosion resistance. However, Cp-Ti was known as bio-inert materials, Ti-6Al-4V alloy has a problem such as high Young modulus, potential loss of the surrounding bone, and to the release of potentially toxic ions from the alloy. To overcome this problem, Ti alloys containing Nb and Hf elements have been used for biomaterials due to low toxicity and high corrosion resistance. Especially, alloying element of Nb was known as β phase stabilizer. The β phase alloy was widely used to replace currently used implant materials. The corrosion resistances of Ti-29Nb-xHf ternary alloys were dependent on Hf content in oral environment solution.

  7. High-temperature grain size stabilization of nanocrystalline Fe–Cr alloys with Hf additions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lulu, E-mail: lli18@ncsu.edu; Saber, Mostafa; Xu, Weizong; Zhu, Yuntian; Koch, Carl C.; Scattergood, Ronald O.

    2014-09-08

    The influence of 1–4 at% Hf additions on the thermal stability of mechanically alloyed nanocrystalline Fe–14Cr alloys was studied in this work. XRD-calculated grain size and microhardness results were reported versus isochronal annealing treatments up to 1100 °C. Microstructural evolution was investigated using channeling contrast FIB imaging and TEM. Grain size of samples with 4 at% Hf was found to be maintained in the nanoscale range at temperatures up to 1000 °C. Zener pinning was considered as a major source of high temperature grain size stabilization. By comparing the Orowan strengthening contribution to the total hardness, the deviation of grain size predictions from the actual grain size in Fe–14Cr–4Hf suggests the presence of thermodynamic stabilization by the solute segregation to grain boundaries (GBs). A predictive thermodynamic model indicates that the thermodynamic stabilization can be expected.

  8. Beta decomposition of (Hf/sub x/Zr/sub 1-x/)80Nb20 ternary alloys

    International Nuclear Information System (INIS)

    Jones, W.B.; Taggart, R.; Polonis, D.H.

    1978-01-01

    The processes of beta decomposition have been examined in ternary alloys of the form (Hf/sub x/Zr/sub 1-x/) 80 Nb 20 to determine the influence of Hf additions to a basic Zr 80 Nb 20 composition. In the chill cast condition, Hf additions have been found to decrease the temperature coefficient of electrical resistivity from a value of -0.0015%/K for the binary Zr 80 Nb 20 alloy to a value of -0.011%/K for a (Hf 50 Zr 50 ) 80 Nb 20 ternary alloy. This change is explained in terms of the bcc lattice instability typical of Ti, Zr, and Hf alloys. The Hf additions enhance the kinetics of omega-phase precipitation during aging at 648 K. The aging of a (Hf 05 Zr 95 ) 80 Nb 20 alloy for 12 h results in the precipitation of a high volume fraction of cuboidal shaped omega-phase particles. A phase separation which results in the formation of solute lean discs (β/sub l/) occurs together with the precipitation of the omega-phase. These discs formed both randomly within the matrix and heterogeneously along dislocations and at grain boundaries

  9. QAPP for Hydraulic Fracturing (HF) Surface Spills Data Analysis

    Science.gov (United States)

    This QAPP provides information concerning the analysis of spills associated with hydraulic fracturing. This project is relevant to both the chemical mixing and flowback and produced water stages of the HF water cycle as found in the HF Study Plan.

  10. Hf layer thickness dependence of resistive switching characteristics of Ti/Hf/HfO2/Au resistive random access memory device

    Science.gov (United States)

    Nakajima, Ryo; Azuma, Atsushi; Yoshida, Hayato; Shimizu, Tomohiro; Ito, Takeshi; Shingubara, Shoso

    2018-06-01

    Resistive random access memory (ReRAM) devices with a HfO2 dielectric layer have been studied extensively owing to the good reproducibility of their SET/RESET switching properties. Furthermore, it was reported that a thin Hf layer next to a HfO2 layer stabilized switching properties because of the oxygen scavenging effect. In this work, we studied the Hf thickness dependence of the resistance switching characteristics of a Ti/Hf/HfO2/Au ReRAM device. It is found that the optimum Hf thickness is approximately 10 nm to obtain good reproducibility of SET/RESET voltages with a small RESET current. However, when the Hf thickness was very small (∼2 nm), the device failed after the first RESET process owing to the very large RESET current. In the case of a very thick Hf layer (∼20 nm), RESET did not occur owing to the formation of a leaky dielectric layer. We observed the occurrence of multiple resistance states in the RESET process of the device with a Hf thickness of 10 nm by increasing the RESET voltage stepwise.

  11. Solvent Effects on Nuclear Magnetic Resonance 2J(C,Hf and 1J(C,Hf Spin–Spin Coupling Constants in Acetaldehyde

    Directory of Open Access Journals (Sweden)

    Angel Esteban

    2003-02-01

    Full Text Available Abstract: The known solvent dependence of 1J(Cc,Hf and 2J(C1,Hf couplings in acetaldehyde is studied from a theoretical viewpoint based on the density functional theory approach where the dielectric solvent effect is taken into account with the polarizable continuum model. The four terms of scalar couplings, Fermi contact, paramagnetic spin orbital, diamagnetic spin orbital and spin dipolar, are calculated but the solvent effect analysis is restricted to the first term since for both couplings it is by far the dominant contribution. Experimental trends of Δ1J(Cc,Hf and Δ2J(C1,Hf Vs ε (the solvent dielectric constant are correctly reproduced although they are somewhat underestimated. Specific interactions between solute and solvent molecules are studied for dimethylsulfoxide, DMSO, solutions considering two different one-to-one molecular complexes between acetaldehyde and DMSO. They are determined by interactions of type C=O---H---C and S=O---H---C, and the effects of such interactions on 1J(Cc,Hf and 2J(C1,Hf couplings are analyzed. Even though only in a semiquantitative way, it is shown that the effect of such interactions on the solvent effects, of Δ1J(Cc,Hf and Δ2J(C1,Hf, tend to improve the agreement between calculated and experimental values. These results seem to indicate that a continuum dielectric model has not enough flexibility for describing quantitatively solvent effects on spin-spin couplings. Apparently, even for relatively weak hydrogen bonding, the contribution from “direct” interactions is of the same order of magnitude as the “dielectric” effect.

  12. Comparison of HfCl4, HfI4, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO2 films deposited by ALD: A DFT study

    International Nuclear Information System (INIS)

    Cortez-Valadez, M.; Fierro, C.; Farias-Mancilla, J.R.; Vargas-Ortiz, A.; Flores-Acosta, M.; Ramírez-Bon, R.; Enriquez-Carrejo, J.L.

    2016-01-01

    Highlights: • Hafnium oxide growth on Si(100) by atomic layer deposition was simulated. • The interface structure was considered as silicate and silicide. • The interface was studied employing DFT. • TDMA-Hf precursor show better interface stability. - Abstract: The final structure of HfO 2 films grown by atomic layer deposition (ALD) after reaction with OH − ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl 4 (hafnium tetrachloride), HfI 4 (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO–H was studied employing the B3LYP (Becke 3-parameter, Lee–Yang–Parr) hybrid functional and the PBE (Perdew–Burke–Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

  13. Comparison of HfCl{sub 4}, HfI{sub 4}, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO{sub 2} films deposited by ALD: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Cortez-Valadez, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Fierro, C.; Farias-Mancilla, J.R. [Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. del Charro 450, Cd. Juárez C.P. 32310, Chihuahua (Mexico); Vargas-Ortiz, A. [Universidad Autónoma de Sinaloa, Facultad de Ingeniería Mochis, Ciudad Universitaria, C.P. 81223 Los Mochis, Sinaloa (Mexico); Flores-Acosta, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Ramírez-Bon, R. [Centro de Investigación y Estudios Avanzados del IPN, Unidad Querétaro, Apdo. Postal 1-798, 76001 Querétaro, Qro. (Mexico); Enriquez-Carrejo, J.L. [Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. del Charro 450, Cd. Juárez C.P. 32310, Chihuahua (Mexico); and others

    2016-06-15

    Highlights: • Hafnium oxide growth on Si(100) by atomic layer deposition was simulated. • The interface structure was considered as silicate and silicide. • The interface was studied employing DFT. • TDMA-Hf precursor show better interface stability. - Abstract: The final structure of HfO{sub 2} films grown by atomic layer deposition (ALD) after reaction with OH{sup −} ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl{sub 4} (hafnium tetrachloride), HfI{sub 4} (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO–H was studied employing the B3LYP (Becke 3-parameter, Lee–Yang–Parr) hybrid functional and the PBE (Perdew–Burke–Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

  14. Analyses of desorbed H2O with temperature programmed desorption technique in sol-gel derived HfO2 thin films

    International Nuclear Information System (INIS)

    Shimizu, H.; Nemoto, D.; Ikeda, M.; Nishide, T.

    2009-01-01

    Hafnium oxide (HfO 2 ) is a promising material for the gate insulator in highly miniaturized silicon (Si) ultra-large-scale-integration (ULSI) devices (32 nm and beyond). In the field chemistry, a sol-gel processing has been used to fabricate HfO 2 thin film with the advantages of low cost, relative simplicity, and easy control of the composition of the layers formed. Temperature-programmed desorption (TPD) has been used not only for analyzing adsorbed gases on the surfaces of bulk sol-gel-derived HfO 2 of sol-gel-derived HfO 2 thin film fired at 350, 450, 550 and 700 deg C in sol-gel derived HfO 2 films in air is investigated using TPD, and also the material characterization of HfO 2 thin films is evaluated by X-ray diffraction (XRD) method. The dielectric constant of the films was also estimated using the capacitance-voltage (C-V) method. TPD is essentially a method of analyzing desorped gases from samples heated by infra-red light as a function of temperature under vacuum conditions using a detector of quadruple mass spectroscopy (QMS). Sol-gel-derived HfO 2 films were fabricated on 76-mm-diameter Si(100) wafers as follows. Hafnia sol solutions were prepared by dissolving HfCl 4 in NH 4 OH solution, followed by the of HCOOH. (author)

  15. Self-diffusion of Er and Hf inpure and HfO2-doped polycrystalline Er2O3

    International Nuclear Information System (INIS)

    Scheidecker, R.W.

    1979-01-01

    Using a tracer technique, self-diffusion of Er and Hf was measured over the approximate temperature interval of 1600 to 1970 0 C in pure and HfO 2 -doped polycryatalline Er 2 O 3 . Up to about 10 m/o HfO 2 dopant level, the Er self-diffusion coefficients followed a relationship based on cation vacancies. Above 10 m/o HfO 2 , deviation from this relationship occurred, apparently due to clustering of cation vacancies and oxygen interstitials around the dopant hafnia ion. The activation energy for the self-diffusion of Er in pure Er 2 O 3 was 82.2 Kcal/mole and increased with the HfO 2 dopant level present. Self-diffusion of Hf was measured in pure Er 2 O 3 having two impurity levels, and a separation of the grain boundary. The volume diffusion of Hf showed both extrinsic and intrinsic behavior with the transition temperature increasing with the impurity level present in Er 2 O 3 . The activation energy for Hf volume diffusion in the intrinsic region was high, i.e. 235 -+ 9.5 Kcal/mole. The grain boundary diffusion was apparently extrinsic over the entire temperature interval Very low Hf self diffusion rates were found in both pure and HfO 2 doped Er 2 O 3 compositions. Despite a clustering effect, the HfO 2 dopant increased the Hf volume diffusion coefficients

  16. High resolution TDPAC measurements on 181Ta in Hf2Fe, Hf2Co and Hf2Rh at high temperature

    International Nuclear Information System (INIS)

    Cekic, B.; Koicki, S.; Ivanovic, N.; Manasijevic, M.; Koteski, V.; Marjanovic, D.

    1998-01-01

    The time differential perturbed angular correlation measurements (TDPAC-method ) on 181 Ta ion probe in Hf 2 Co, Hf 2 Fe and Hf 2 Rh intermetallic compounds have been performed at 1170 K, using a fast - slow time spectrometer consisting of two BaF 2 detectors. The results of the measurements show the presence of two independent electric quadrupole interactions, compatible with the crystalline structure of these polycrystalline compounds. (authors)

  17. Mesocrystals luminescent BaZrHfO{sub 3} synthesized via hydrothermal process assisted by microwave

    Energy Technology Data Exchange (ETDEWEB)

    Fassbender, Rafael Uarth, E-mail: uarth.fisica@gmail.com

    2016-07-01

    Full text: The Barium Zirconate (BaZrO{sub 3}), is a ceramic oxide belonging to the functional group of perovskites (ABO{sub 3}), this compound can be doped with hafniun (Hf) in solid solution by microwave assisted hydrothermal method (MAH) radioluminescent increases their properties. This method allows to obtain barium zirconate at low temperature as 140 deg C and short times as 160 minutes. The choice of Hafnium (Hf) as a dopant is based on its similarity with Zirconium (Zr), another good reason for this choice is that the Hafnium has intrinsic luminescent characteristics. In general, radioluminescent materials have high density and high atomic mass (atomic number of Hafnium is 72), thereby facilitating the absorption of ionizing radiation to convert it into visible light, this characteristic is strongly dependent on the morphology and especially the electronic structure of (BaZrO{sub 3}). This work consisted in production of barium zirconate powders doped 1-2-4-8-16% (Hf) using (MAH) method. For the characterization of the powders was employed methods : a) X-ray diffraction, b) Raman Spectroscopy, c) Xanes, d) photoluminescence spectroscopy. After the electronic and structural characterization the powders were introduced in a polymeric resin (nylon-BZO), one new characterizations will be performed to validate the results obtained in the production of films to the results already obtained for the powders. We conclude so far, that the powders-doped with 16% Hf has an intense luminescent emission compared to the powders with less concentration of Hf. The small structural change that causes the Hf in (BZO) is considered as a secondary factory. (author)

  18. Magnetic properties of Hf177 and Hf180 in the strong-coupling deformed model

    Science.gov (United States)

    Muto, S.; Stone, N. J.; Bingham, C. R.; Stone, J. R.; Walker, P. M.; Audi, G.; Gaulard, C.; Köster, U.; Nikolov, J.; Nishimura, K.; Ohtsubo, T.; Podolyak, Z.; Risegari, L.; Simpson, G. S.; Veskovic, M.; Walters, W. B.

    2014-04-01

    This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2-, 51.4 m, 2740 keV state in Hf177 and the 8-, 5.5 h, 1142 keV state in Hf180 by the method of on-line nuclear orientation. Also included are results on the angular distributions of γ transitions in the decay of the Hf177 isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2+, 1.1 s, isomer at 1315 keV and on the 9/2+, 0.663 ns, isomer at 321 keV. The new results are discussed in the light of the recently reported finding of systematic dependence of the behavior of the gR parameter upon the quasiproton and quasineutron make up of high-K isomeric states in this region.

  19. Electric Field Gradients at Hf and Fe Sites in Hf2Fe Recalculated

    International Nuclear Information System (INIS)

    Belosevic-Cavor, J.; Cekic, B.; Novakovic, N.; Koteski, V.; Milosevic, Z.

    2004-01-01

    The electric field gradients (EFG) of the Hf 2 Fe intermetallic compound were calculated using the full-potential linearized augmented plain-wave (FP-LAPW) method as embodied in the WIEN 97 code. The obtained values are compared with other ab-initio calculations and on a qualitative basis with the previously reported experimental data obtained from TDPAC. The calculated results, -23.1.10 21 V/m 2 and 2.7.10 21 V/m 2 for Hf 48f and Fe 32e position, respectively, are in excellent agreement with experimental data (23.4.10 21 V/m 2 and 2.7.10 21 V/m 2 ), better than those reported in earlier calculations. The calculated EFG for Hf 16c position (4.2.10 21 V/m 2 ) is stronger than the experimental one (1.1.10 21 V/m 2 ).

  20. Copper-Sulfate Pentahydrate as a Product of the Waste Sulfuric Acid Solution Treatment

    Science.gov (United States)

    Marković, Radmila; Stevanović, Jasmina; Avramović, Ljiljana; Nedeljković, Dragutin; Jugović, Branimir; Stajić-Trošić, Jasna; Gvozdenović, Milica

    2012-12-01

    The aim of this study is synthesis of copper-sulfate pentahydrate from the waste sulfuric acid solution-mother liquor generated during the regeneration process of copper bleed solution. Copper is removed from the mother liquor solution in the process of the electrolytic treatment using the insoluble lead anodes alloyed with 6 mass pct of antimony on the industrial-scale equipment. As the result of the decopperization process, copper is removed in the form of the cathode sludge and is precipitated at the bottom of the electrolytic cell. By this procedure, the content of copper could be reduced to the 20 mass pct of the initial value. Chemical characterization of the sludge has shown that it contains about 90 mass pct of copper. During the decopperization process, the very strong poison, arsine, can be formed, and the process is in that case terminated. The copper leaching degree of 82 mass pct is obtained using H2SO4 aqueous solution with the oxygen addition during the cathode sludge chemical treatment at 80 °C ± 5 °C. Obtained copper salt satisfies the requirements of the Serbian Standard for Pesticide, SRPS H.P1. 058. Therefore, the treatment of waste sulfuric acid solutions is of great economic and environmental interest.

  1. Study of fatigue crack nucleation in 12% chromium stainless steel in sulphate and phosphate solutions

    International Nuclear Information System (INIS)

    Shalaby, H.M.; Begley, J.A.; Macdonald, D.D.

    1989-01-01

    The morphology of fatigue crack nucleation has been studied in 12%Cr stainless steel at a single stress level of 448 MN m -2 in deaerated H 2 SO 4 -Na 2 SO 4 -NaOH ([SO 4 2- ] = 0.01M and 1M) and in H 3 PO 4 -NaOH ([PO 4 3- ] = 0.01M and 1M) solutions at pH 2, 7 and 10 at 100 0 C. In sulphate solutions at pH 2, the specimen suffered overall surface attack without the initiation of microcracks. The surface attack intensified at the prior austenite grain boundaries, martensite platelet boundaries, and non-metallic inclusions. In contrast, cracks initiated transgranularly in sulphate solutions at pH 7 and 10 with the development of selective attack at crack sites at later stages in the fatigue life. This attack was ascribed to local acidification as a result of hydrolysis of corrosion products extruded from inside the cracks. Long cracks with crack branching and debonded zones were observed in all phosphate solutions, except in 0.01M phosphate solution at pH 7. In this latter environment, short intrusion-extrusion microcracks were observed. This difference in behaviour was attributed to changes in the characteristics of the passive film as influenced by the local environmental conditions, mechanical rupture by plastic deformation, and electrochemical differences at the metal surface. (author)

  2. Lifetime of the first excited 2{sup +} state in {sup 172}Hf and {sup 174}Hf

    Energy Technology Data Exchange (ETDEWEB)

    Gerst, Rosa-Belle; Stegemann, Simon; Jolie, Jan; Regis, Jean-Marc; Rudigier, Matthias; Saed-Samii, Nima; Zell, Karl Oskar [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany)

    2014-07-01

    Using the {sup 170}Yb(α,2n) and {sup 172}Yb(α,2n) reactions the lifetimes of the first excited 2{sup +} state in {sup 172}Hf and {sup 174}Hf have been measured in fast-timing experiments using the Cologne Orange-Spectrometer and 6 LaBr{sub 3}(Ce)-Detectors. The lifetimes were obtained analyzing e{sup -}-γ-coincidence time-spectra with the slope method. The new and more precise lifetimes correct existing, outdated lifetimes in nuclear databases. Additionally, the systematics of the B(E2,2{sub 1}{sup +}→0{sub 1}{sup +}) is studied.

  3. Anion exchange behaviour of Zr, Hf, Nb, Ta and Pa as homologues of RF and Db in fluoride medium

    Energy Technology Data Exchange (ETDEWEB)

    Monroy G, F. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Trubert, D.; Brillard, L.; Hussonnois, M.; Constantinescu, O.; Le Naour, C., E-mail: fabiola.monroy@inin.gob.m [Institut de Physique Nucleaire, F-91406 Orsay, France (France)

    2010-07-01

    Studies of the chemical property of trans actinide elements are very difficult due to their short half-lives and extremely small production yields. However it is still possible to obtain considerable information about their chemical properties, such as the most stable oxidation states in aqueous solution, complexing ability, etc., comparing their behaviour with their lighter homologous in the periodic table. In order to obtain a better knowledge of the behaviour of rutherfordium, RF (element 104), dub nium, Db (element 105) in HF medium, the sorption properties of Zr, Hf, Nb, Ta an Pa, homologues of RF and Db, were studied in NH{sub 4}F/HClO{sub 4} medium in this work. Stability constants of the fluoride complexes of these elements were experimentally obtained from K{sub d} obtained at different F{sup -} and H{sup +} concentrations. The anionic complexes: [Zr(Hf)F{sub 5}]{sup -}, [Zr(Hf)F{sub 6}]{sup 2-}, [Zr(Hf)F{sub 7}]{sup 3-}, [Ta(Pa)F{sub 6}]{sup -}, [Ta(Pa)F{sub 7}]{sup 2-}, [Ta(Pa)F{sub 8}]{sup 3-}, [NbOF{sub 4}]{sup -} and [NbOF{sub 5}]{sup 2-} are present as predominant species in the HF range over investigation. (Author)

  4. Anion exchange behaviour of Zr, Hf, Nb, Ta and Pa as homologues of RF and Db in fluoride medium

    International Nuclear Information System (INIS)

    Monroy G, F.; Trubert, D.; Brillard, L.; Hussonnois, M.; Constantinescu, O.; Le Naour, C.

    2010-01-01

    Studies of the chemical property of trans actinide elements are very difficult due to their short half-lives and extremely small production yields. However it is still possible to obtain considerable information about their chemical properties, such as the most stable oxidation states in aqueous solution, complexing ability, etc., comparing their behaviour with their lighter homologous in the periodic table. In order to obtain a better knowledge of the behaviour of rutherfordium, RF (element 104), dub nium, Db (element 105) in HF medium, the sorption properties of Zr, Hf, Nb, Ta an Pa, homologues of RF and Db, were studied in NH 4 F/HClO 4 medium in this work. Stability constants of the fluoride complexes of these elements were experimentally obtained from K d obtained at different F - and H + concentrations. The anionic complexes: [Zr(Hf)F 5 ] - , [Zr(Hf)F 6 ] 2- , [Zr(Hf)F 7 ] 3- , [Ta(Pa)F 6 ] - , [Ta(Pa)F 7 ] 2- , [Ta(Pa)F 8 ] 3- , [NbOF 4 ] - and [NbOF 5 ] 2- are present as predominant species in the HF range over investigation. (Author)

  5. Mixed Messages from Garnet Lu-Hf and Sm-Nd Geochronology

    Science.gov (United States)

    Vervoort, J. D.; Wang, D.; Johnson, T. A.

    2017-12-01

    Garnet geochronology provides important information on the timing and conditions of metamorphism. As a major indicator mineral formed during metamorphism, its direct dating can not only help establish the timing of metamorphism, provide the "t" for P-T-t paths, but also, if the dated garnet can be placed in a textural context, can provide information on the timing of deformational features. With advances in chemistry and mass spectrometry, garnet Lu-Hf and Sm-Nd geochronology has become an important geochronological tool and we can now reliably (if not routinely) date a wide variety of garnet compositions formed under diverse conditions. In the course of dating a variety of lithologies using both Lu-Hf and Sm-Nd isotope systems, however, some intriguing results have emerged. Although there are many examples where the Lu-Hf and Sm-Nd systems give the same date within uncertainty, there are also many cases where these systems yield significantly different dates, and the differences between these dates can be considerable—many 10's of Ma of and even 100's of Ma. For example, in garnet-bearing Mesoproterozoic gneisses from across the Blue Ridge Province in Virginia, both Lu-Hf and Sm-Nd analyses (determined on the same solutions) define narrow time spans, but with the Sm-Nd dates systematically younger (for orthogneisses Lu-Hf dates are 1032 to 1019 Ma whereas Sm-Nd dates are 965 to 949 Ma—a difference of 67 to 80 Ma). There are many other examples of systematically younger Sm-Nd garnet dates in both the literature and with our ongoing research. Potential explanations for these differences include: 1) strong partitioning of Lu into garnet during growth yielding ages weighted toward the beginning of growth; 2) faster Lu diffusion from high Lu regions after garnet formation, potentially leading to isochron rotation and anomalously old Lu-Hf dates; and 3) differences in closure temperatures of the two isotope systems. We will review several examples of divergent Lu-Hf

  6. HF Radio Astronomy from a Small Satellite

    Science.gov (United States)

    2016-06-15

    SSC16-XI-03 HF Radio Astronomy from a Small Satellite Frank C. Robey1, Mary Knapp2, Alan J. Fenn1, Mark Silver1, Kerry Johnson1 Frank J. Lind3...frequency end of the electromagnetic spectrum (below 15 MHz) is one of the least explored windows in observational astronomy . Observations at these...pdf. [Accessed: 17-Oct-2015]. 3. G. Hallinan, “The Owens Valley LWA,” in Exascale Radio Astronomy , 2014, vol. 2. 4. C. J. Lonsdale, R. J. Cappallo

  7. High-aspect-ratio HfC nanobelts accompanied by HfC nanowires: Synthesis, characterization and field emission properties

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Song, E-mail: tiansong22@126.com [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); School of Materials Science and Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Zhang, Yulei; Ren, Jincui; Qiang, Xinfa; Zhang, Shouyang [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Li, Hejun, E-mail: lihejun@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China)

    2017-04-30

    Highlights: • HfC naobelts accompanied by HfC nanowires were synthesized by a catalytic CVD method. • HfC nanobelts as a novel structure of HfC ceramic are reported for the first time. • HfC nanobelts have 100–200 μm in lengths and reach up to 10 μm in widths. • The synthesized product is promising field nanoemitters. - Abstract: As a key refractory carbide, hafnium carbide (HfC) is commonly used as structural materials while the field emission (FE) application of HfC in the field of vacuum microelectronics is almost the only one for functional material purposes. Based on its outstanding physical and chemical characteristics, HfC is identified as a potential candidate with satisfactory mechanical properties and long-term and/or high-temperature FE stability for future applications in high-performance field emitters. However, the development of HfC in various FE applications is hindered because it is not facile to fabricate large-scale low-dimensional HfC field nanoemitters. Herein, High-aspect-ratio HfC nanobelts accompanied by HfC nanowires were synthesized on a large scale by a traditional and simple catalytic chemical vapor deposition (CVD) method. Classical vapor–liquid–solid (VLS) theory was employed to explain the growth of the HfC nanowires and nanobelts along axial direction. The thin HfO{sub 2} shell and thin C layer surrounding the nanostructures might give rise to the diameter fluctuation of HfC nanowires and the width increase of HfC nanobelts in lateral direction. Field emission results show that the high-aspect-ratio HfC nanobelts accompanied by the nanowires are promising field nanoemitters, which exhibit excellent field emission properties with a fairly low turn-on field of ∼1.5 V μm{sup −1} and a low current fluctuation less than ∼10%. This suggests that HfC ceramics with high-aspect-ratio nanostructures are ideal cathode material for various field emission applications.

  8. Design and Fabrication of Interdigital Nanocapacitors Coated with HfO2

    Directory of Open Access Journals (Sweden)

    Gabriel González

    2015-01-01

    Full Text Available In this article nickel interdigital capacitors were fabricated on top of silicon substrates. The capacitance of the interdigital capacitor was optimized by coating the electrodes with a 60 nm layer of HfO2. An analytical solution of the capacitance was compared to electromagnetic simulations using COMSOL and with experimental measurements. Results show that modeling interdigital capacitors using Finite Element Method software such as COMSOL is effective in the design and electrical characterization of these transducers.

  9. Ab initio theoretical study of dipole-bound anions of molecular complexes: (HF)3- and (HF)4- anions

    Science.gov (United States)

    Ramaekers, Riet; Smith, Dayle M. A.; Smets, Johan; Adamowicz, Ludwik

    1997-12-01

    Ab initio calculations have been performed to determine structures and vertical electron detachment energy (VDE) of the hydrogen fluoride trimer and tetramer anions, (HF)3- and (HF)4-. In these systems the excess electron is bound by the dipole field of the complex. It was determined that, unlike the neutral complexes which prefer the cyclic structures, the equilibrium geometries of the anions have "zig-zag" shapes. For both complexes the predicted VDEs are positive [210 meV and 363 meV for (HF)3- and (HF)4-, respectively], indicating that the anions are stable systems with respect to the vertical electron detachment. These results were obtained at the coupled-cluster level of theory with single, double and triple excitations [CCSD(T) method; the triple-excitation contribution in this method is calculated approximately using the perturbation approach] with the anion geometries obtained using the second-order Møller-Plesset perturbation theory (MP2) method. The same approach was also used to determine the adiabatic electron affinities (AEA) of (HF)3 and (HF)4. In addition to the electronic contribution, we also calculated the contributions (using the harmonic approximation) resulting from different zero-point vibration energies of the neutral and anionic clusters. The calculations predicted that while the AEA of (HF)3 is positive (44 meV), the AEA for (HF)4 is marginally negative (-16 meV). This suggests that the (HF)3- anion should be a stable system, while the (HF)4- is probably metastable.

  10. Mapping high-latitude plasma convection with coherent HF radars

    International Nuclear Information System (INIS)

    Ruohoniemi, J.M.; Greenwald, R.A.; Baker, K.B.; Villain, J.-P.; Hanuise, C.; Kelly, J.

    1989-01-01

    In this decade, a new technique for the study of ionosphere electrodynamics has been implemented in an evolving generation of high-latitude HF radars. Coherent backscatter from electron density irregularities at F region altitudes is utilized to observe convective plasma motion. The electronic beam forming and scanning capabilities of the radars afford an excellent combination of spatial (∼50 km) and temporal (∼1 min) resolution of the large-scale (∼10 6 km 2 ) convection pattern. In this paper, we outline the methods developed to synthesize the HF radar data into two-dimensional maps of convection velocity. Although any single radar can directly measure only the line-of-sight, or radial, component of the plasma motion, the convection pattern is sometimes so uniform and stable that scanning in azimuth serves to determine the transverse component as well. Under more variable conditions, data from a second radar are necessary to unambiguously resolve velocity vectors. In either case, a limited region of vector solution can be expanded into contiguous areas of single-radar radial velocity data by noting that the convection must everywhere be divergence-free, i.e., ∇·v=0. It is thus often possible to map velocity vectors without extensive second-radar coverage. We present several examples of two-dimensional velocity maps. These show instances of L shell-aligned flow in the dusk sector, the reversal of convection near magnetic midnight, and counterstreaming in the dayside cleft. We include a study of merged coherent and incoherent radar data that illustrates the applicability of these methods to other ionospheric radar systems. copyright American Geophysical Union 1989

  11. Crystal structure of the binder phase in a model HfC-TiC-Ni material

    International Nuclear Information System (INIS)

    Heiligers, Christiane; Neethling, Johannes H.

    2008-01-01

    The crystal structure of the binder phase in a model HfC-TiC-Ni sample produced by hot pressing is investigated. The nature of the binder depends on the amount of Hf and Ti that remains in solution with Ni after cooling. Four different crystal structures are identified by analysis of electron diffraction patterns obtained using transmission electron microscopy techniques and the composition of the phases determined by energy dispersive X-ray spectrometry. Three of the phases are cubic; Ni, Ni 3 (Ti,Hf) and Ni 23 (Ti,Hf) 6 with lattice parameters of 3.52 ± 0.05, 3.52 ± 0.03 and 10.70 ± 0.40 A, respectively. The hexagonal phase is an intermetallic Ni 3 Ti phase, with lattice parameters of a = b = 5.00 ± 0.20 A and c = 8.16 ± 0.20 A. The crystal structures are confirmed by simulations of the electron diffraction patterns using JEMS software

  12. Structure, chemistry and luminescence properties of dielectric La{sub x}Hf{sub 1-x}O{sub y} films

    Energy Technology Data Exchange (ETDEWEB)

    Kaichev, V.V., E-mail: vvk@catalysis.ru [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Smirnova, T.P.; Yakovkina, L.V. [Nikolaev Institute of Inorganic Chemistry, Novosibirsk (Russian Federation); Ivanova, E.V.; Zamoryanskaya, M.V. [Ioffe Physical-Technical Institute, St. Petersburg (Russian Federation); Saraev, A.A. [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Pustovarov, V.A. [Ural State Technical University, Ekaterinburg (Russian Federation); Perevalov, T.V.; Gritsenko, V.A. [Novosibirsk State University, Novosibirsk (Russian Federation); Rzhanov Institute of Semiconductor Physics, Novosibirsk (Russian Federation)

    2016-06-01

    Dielectric films of La{sub 2}O{sub 3}, HfO{sub 2}, and La{sub x}Hf{sub 1-x}O{sub y} were synthesized by metal-organic chemical vapor deposition. Structural, chemical, and luminescence properties of the films were studied using X-ray photoelectron spectroscopy, methods of X-ray diffraction and selected area electron diffraction, high-resolution transmission electron microscopy, and a cathodoluminescence technique. It was found that doping of hafnium oxide with lanthanum leads to the formation of a continuous series of solid solutions with a cubic structure. This process is accompanied by the formation of oxygen vacancies in the HfO{sub 2} lattice. Cathodoluminescence spectra of the La{sub x}Hf{sub 1-x}O{sub y}/Si films exhibited a wide band with the maximum near 2.4–2.5 eV, which corresponds to the blue emission. Quantum-chemical calculations showed that this blue band is due to oxygen vacancies in the HfO{sub 2} lattice. - Highlights: • HfO{sub 2} and solid solution La{sub x}Hf{sub 1-x}O{sub y} films were synthesized by MOCVD. • The continuous series of solid solutions with a cubic structure was formed at La doping of HfO{sub 2}. • Cathodoluminescence band at 2.4–2.5 eV is observed due to the oxygen vacancies in La{sub x}Hf{sub 1-x}O{sub y}. • The cathodoluminescence decreases in intensity when the La concentration increases.

  13. Thermoelectric properties of doped BaHfO_3

    International Nuclear Information System (INIS)

    Dixit, Chandra Kr.; Bhamu, K. C.; Sharma, Ramesh

    2016-01-01

    We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO_3 by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO_3 doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO_3 is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO_3 is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

  14. Nuclear quadrupole interactions in ferroelectric compounds of HF181

    International Nuclear Information System (INIS)

    Kunzler, J.V.

    1971-01-01

    Measurements of nuclear quadrupole interaction constants in perovkite-type compounds of PbHfO 3 , SnhfO 3 , CaHfO 3 e SrHfO 3 have been performed using the perturbed angular correlation technique. A range of fundamental frequencies from 150 to 550 Megaradians persecond was determined. The variation of quadrupole constants has been discussed through the molecular orbital theory

  15. Application of HF Radar in Hazard Management

    Directory of Open Access Journals (Sweden)

    Mal Heron

    2016-01-01

    Full Text Available A review is given of the impact that HF radars are having on the management of coastal hazards. Maps of surface currents can be produced every 10–20 minutes which, in real time, improve navigation safety in restricted areas commonly found near ports and harbours. The time sequence of surface current maps enables Lagrangian tracking of small parcels of surface water, which enables hazard mitigation in managing suspended sediments in dredging, in emergency situations where flotsam and other drifting items need to be found, and in pollution control. The surface current measurement capability is used to assist tsunami warnings as shown by the phased-array data from Chile following the Great Tohoku Earthquake in 2011. The newly launched Tsunami Warning Center in Oman includes a network of phased-array HF radars to provide real-time tsunami monitoring. Wind direction maps can be used to locate the position of cold fronts in the open ocean and to monitor the timing and strength of sea-breeze fronts in key locations.

  16. Interatomic potential to predict the favored and optimized compositions for ternary Cu-Zr-Hf metallic glasses

    International Nuclear Information System (INIS)

    Luo, S. Y.; Cui, Y. Y.; Dai, Y.; Li, J. H.; Liu, B. X.

    2012-01-01

    Under the framework of smoothed and long range second-moment approximation of tight-binding, a realistic interatomic potential was first constructed for the Cu-Zr-Hf ternary metal system. Applying the constructed potential, Monte Carlo simulations were carried out to compare the relative stability of crystalline solid solution versus its disordered counterpart over the entire composition triangle of the system (as a function of alloy composition). Simulations not only reveal that the origin of metallic glass formation but also determine, in the composition triangle, a quadrilateral region, within which metallic glass formation is energetically favored. It is proposed to define the energy differences between the crystalline solid solutions and disordered states as the driving force for amorphization and the corresponding calculations pinpoint an optimized composition locating at an composition of Cu 55 Zr 10 Hf 35 , around which the driving force for metallic glass formation reaches its maximum, suggesting that the ternary Cu-Zr-Hf metallic glasses designed to have the compositions around Cu 55 Zr 10 Hf 35 could be more stable than other alloys in the system. Moreover, for the Cu 55 Zr 10 Hf 35 metallic glass, the Voronoi tessellation calculations reveal some interesting features of its atomic configurations and coordination polyhedra distribution.

  17. Hf isotope evidence for a hidden mantle reservoir

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Simonetti, A.; Stevenson, R.K.

    2002-01-01

    High-precision Hf isotopic analyses and U-Pb ages of carbonatites and kimberlites from Greenland and eastern North America, including Earth's oldest known carbonatite (3 Ga), indicate derivation from an enriched mantle source. This previously unidentified mantle reservoir-marked by an unradiogenic...... Hf isotopic composition and preserved in the deep mantle for at least 3 b.y.-may account for the mass imbalance in Earth's Hf-Nd budget. The Hf isotopic data presented here support a common mantle source region and genetic link between carbonatite and some oceanic-island basalt volcanoes....

  18. Microstructural characterization of as-cast hf-b alloys

    Directory of Open Access Journals (Sweden)

    João Carlos Jânio Gigolotti

    2012-04-01

    Full Text Available An accurate knowledge of several metal-boron phase diagrams is important to evaluation of higher order systems such as metal-silicon-boron ternaries. The refinement and reassessment of phase diagram data is a continuous work, thus the reevaluation of metal-boron systems provides the possibility to confirm previous data from an investigation using higher purity materials and better analytical techniques. This work presents results of rigorous microstructural characterization of as-cast hafnium-boron alloys which are significant to assess the liquid composition associated to most of the invariant reactions of this system. Alloys were prepared by arc melting high purity hafnium (minimum 99.8% and boron (minimum 99.5% slices under argon atmosphere in water-cooled copper crucible with non consumable tungsten electrode and titanium getter. The phases were identified by scanning electron microscopy, using back-scattered electron image mode and X-ray diffraction. In general, a good agreement was found between our data and those from the currently accepted Hafnium-Boron phase diagram. The phases identified are αHfSS and B-RhomSS, the intermediate compounds HfB and HfB2 and the liquide L. The reactions are the eutectic L ⇔ αHfSS + HfB and L ⇔ HfB2 + B-Rhom, the peritectic L + HfB2 ⇔ HfB and the congruent formation of HfB2.

  19. Waste acid detoxification and reclamation

    International Nuclear Information System (INIS)

    Brouns, T.M.; Stewart, T.L.

    1988-01-01

    Economically feasible processes that reduce the volume, quantity, and toxicity of metal-bearing waste acids by reclaiming, reusing, and recycling spent acids and metal salts are being developed and demonstrated. The acids used in the demonstrations are generated during metal-finishing operations used in nuclear fuel fabrication; HF-HNO 3 , HNO 3 , and HNO 3 -H 2 SO 4 wastes result from Zr etching, Cu stripping, and chemical milling of U. At discharge, wastes contain high concentrations of acid and one major metal impurity. The waste minimization process used to reclaim acid from these three streams incorporates three processes for acid regeneration and reclamation. Normally, HNO 3 remains in the bottoms when an aqueous acid solution is distilled; however, in the presence of H 2 SO 4 , HNO 3 will distill to the overhead stream. In this process, nitrates and fluorides present as free acid and metal salts can be reclaimed as acid for recycle to the metal-finishing processes. Uranium present in the chemical milling solution can be economically recovered from distillation bottoms and refined. Using acid distillation, the volume of chemical milling solution discharged as waste can be reduced by as much as 60% depending on the H 2 SO 4 concentration. A payback period of 2.2 years has been estimated for this process. The development and demonstration of precipitation and distillation processes for detoxification and reclamation of waste acid is supported by the US Department of Energy's Hazardous Waste Remedial Actions Program (HAZWRAP)

  20. Creep Properties of NiAl-1Hf Single Crystals Re-Investigated

    Science.gov (United States)

    Whittenberger, J. Daniel; Locci, Ivan E.; Darolia, Ram; Bowman, Randy R.

    2000-01-01

    ingots were subjected to several heat treatment schedules, examined by transmission electron microscopy, and tested in both compression and tension. An example of the microstructure found in a [001]-oriented NiAl-1Hf specimen after a solution treatment at 1317 C for 50 hr followed by air cooling is illustrated in the image on the left, where the NiAl matrix contains a uniform distribution of nanometer-scale Gphase (Ni16Hf6Si7) precipitates. Other heat treating schedules produced microstructures with nanometer-sized G-phase cubes and plates or, in an extreme case, produced a microstructure with all the G-phase converted to Heusler (Ni2AlHf) particles. The results of 1027 C creep strength and strain rate testing are illustrated which summarizes data from tensile and compressive testing of samples cut from all four NiAl-1Hf ingots and subjected to a variety of heat treatment schedules. With one exception, all the strength values lie in a narrow band that spans six orders of magnitude in strain rate. The only factor that produced results outside of this band was the heat treatment schedule that dissolved all the G-phase and replaced it with Heusler precipitates. The results portrayed in this figure lead to the important practical conclusion that the elevated-temperature creep properties of NiAl-1Hf single crystals are reproducible and are not affected by small variations in alloy chemistry from ingot to ingot or by different initial distributions of G-phase in the heat-treated alloy. The only variable in this study that produced a significant and delerious effect on mechanical strength was a post-solution heat treatment that lead to the complete disappearance of the G-phase in favor of Heusler precipitates.

  1. The Formation and Spatiotemporal Progress of the pH Wave Induced by the Temperature Gradient in the Thin-Layer H2O2-Na2S2O3-H2SO4-CuSO4 Dynamical System.

    Science.gov (United States)

    Jędrusiak, Mikołaj; Orlik, Marek

    2016-03-31

    The H2O2-S2O3(2-)-H(+)-Cu(2+) dynamical system exhibits sustained oscillations under flow conditions but reveals only a single initial peak of the indicator electrode potential and pH variation under batch isothermal conditions. Thus, in the latter case, there is no possibility of the coupling of the oscillations and diffusion which could lead to formation of sustained spatiotemporal patterns in this process. However, in the inhomogeneous temperature field, due to dependence of the local reaction kinetics on temperature, spatial inhomogeneities of pH distribution can develop which, in the presence of an appropriate indicator, thymol blue, manifest themselves as the color front traveling along the quasi-one-dimensional reactor. In this work, we describe the experimental conditions under which the above-mentioned phenomena can be observed and present their numerical model based on thermokinetic coupling and spatial coordinate introduced to earlier isothermal homogeneous kinetic mechanism.

  2. Simultaneous analysis of rotational and vibrational-rotational spectra of DF and HF to obtain irreducible molecular constants for HF

    International Nuclear Information System (INIS)

    Horiai, Koui; Uehara, Hiromichi

    2011-01-01

    Graphical abstract: Available rotational and vibrational-rotational spectral lines of DF and HF are analyzed simultaneously using a non-Born-Oppenheimer effective Hamiltonian. Research highlights: → Simultaneous analysis of DF and HF spectral data. → Application of a non-Born-Oppenheimer effective Hamiltonian. → Twenty irreducible molecular constants for HF have been determined. - Abstract: Analytic expressions of corrections for the breakdown of the Born-Oppenheimer approximation to Dunham's Y ij with optimal parameters, i.e., determinable clusters of expansion coefficients, are applied to a data analysis of the rotational and vibrational-rotational transitions of HF reported in the literature. All the available spectral lines of the two isotopologues, DF and HF, are simultaneously fitted to a single set of molecular parameters of HF within experimental errors. Fitting of a data set of 595 spectral transitions for DF and HF has generated only 20 minimal independent parameter values, i.e., 'irreducible' molecular constants of HF, that are sufficient to precisely generate 82 Y ij coefficients and 144 band constants in total: 41 Y ij and 72 band constants each for DF and HF.

  3. Utilization of antenna arrays in HF systems

    Directory of Open Access Journals (Sweden)

    Louis Bertel

    2009-06-01

    Full Text Available

    Different applications of radio systems are based on the implementation of antenna arrays. Classically, radio direction

    finding operates with a multi channel receiving system connected to an array of receiving antennas. More

    recently, MIMO architectures have been proposed to increase the capacity of radio links by the use of antenna

    arrays at both the transmitter and receiver.

    The first part of this paper describes some novel experimental work carried out to examine the feasibility of applying

    MIMO techniques for communications within the HF radio band. A detailed correlation analysis of a variety

    of different antenna array configurations is presented. The second section of the paper also deals with HF

    MIMO communications, focusing on the problem from a modelling point of view. The third part presents a sensitivity

    analysis of different antenna array structures for HF direction finding applications. The results demonstrate

    that when modelling errors, heterogeneous antenna arrays are more robust in comparison to homogeneous structures


  4. Determining the Sensitivity of the Hf-Nd Proxy to Glacial Weathering

    Science.gov (United States)

    Namsinh, A.; Scher, H.; Piotrowski, A. M.

    2017-12-01

    The history of polar ice sheets through the Cenozoic is incompletely known. Estimates of the onset of northern hemisphere glaciation range from the Pliocene to mid-Eocene and precursor Antarctic glaciations are believed to have commenced in the middle Eocene. Uncertainty surrounding the history of ice sheets has resulted in debates about the sensitivity of ice sheets to changes in atmospheric CO2 through the Cenozoic. Geochemical proxies for continental weathering — particularly those that are sensitive to mechanical breakdown of the upper continental crust by ice sheets — could improve the fidelity of paleoclimate reconstructions of ice sheet history. Coupled hafnium (Hf) and neodymium (Nd) isotopes in seawater and authigenic sediment phases show a strong correlation with mechanical weathering rates, however the proxy has not been systematically tested on Pleistocene time scales. We measured the Hf and Nd isotope ratios of authigenic and detrital phases of sediment cores from 1150 m to 4045 m depth on the Rockall Plateau in the NE Atlantic Ocean. Our study is limited to the LGM, deglaciation and Holocene intervals. The authigenic fraction was extracted from bulk sediments by leaching with dilute hydroxylamine hydrochloride and EDTA to prevent readsorption of Hf. A stronger leach solution was then used to isolate the terrigenous detrital fraction. The fidelity of the seawater signal obtained by leaching is assessed by comparison of leachate eNd values to previously published eNd values from uncleaned forams from the same depth intervals. Initial tests with Holocene and deglacial samples verify that leachate eNd values are statistically indistinguishable from uncleaned forams. Shale-normalized REE patterns for leachates reveal negative Ce anomalies and a MREE enrichment typical of Fe-Mn oxydydroxide phases. Coupled Hf-Nd isotopes from authigenic leachates from our initial tests fall along the Seawater Array when plotted on a Hf-Nd isotope diagram, confirming

  5. Straining electrode behavior and corrosion resistance of nickel base alloys in high temperature acidic solution

    International Nuclear Information System (INIS)

    Yamanaka, Kazuo

    1992-01-01

    Repassivation behavior and IGA resistance of nickel base alloys containing 0∼30 wt% chromium was investigated in high temperature acid sulfate solution. (1) The repassivation rate was increased with increasing chromium content. And so the amounts of charge caused by the metal dissolution were decreased with increasing chromium content. (2) Mill-annealed Alloy 600 suffered IGA at low pH environment below about 3.5 at the fixed potentials above the corrosion potential in 10%Na 2 SO 4 +H 2 SO 4 solution at 598K. On the other hand, thermally-treated Alloy 690 was hard to occur IGA at low pH environments which mill-annealed Alloy 600 occurred IGA. (3) It was considered that the reason, why nickel base alloys containing high chromium content such as Alloy 690 (60%Ni-30%Cr-10%Fe) had high IGA/SCC resistance in high temperature acidic solution containing sulfate ion, is due to both the promotion of the repassivation and the suppression of the film dissolution by the formation of the dense chromium oxide film

  6. Development and validation of a house finch interleukin-1β (HfIL-1β) ELISA system.

    Science.gov (United States)

    Kim, Sungwon; Park, Myeongseon; Leon, Ariel E; Adelman, James S; Hawley, Dana M; Dalloul, Rami A

    2017-08-30

    A unique clade of the bacterium Mycoplasma gallisepticum (MG), which causes chronic respiratory disease in poultry, has resulted in annual epidemics of conjunctivitis in North American house finches since the 1990s. Currently, few immunological tools have been validated for this songbird species. Interleukin-1β (IL-1β) is a prototypic multifunctional cytokine and can affect almost every cell type during Mycoplasma infection. The overall goal of this study was to develop and validate a direct ELISA assay for house finch IL-1β (HfIL-1β) using a cross-reactive chicken antibody. A direct ELISA approach was used to develop this system using two different coating methods, carbonate and dehydration. In both methods, antigens (recombinant HfIL-1b or house finch plasma) were serially diluted in carbonate-bicarbonate coating buffer and either incubated at 4 °C overnight or at 60 °C on a heating block for 2 hr. To generate the standard curve, rHfIL-1b protein was serially diluted at 0, 3, 6, 9, 12, 15, 18, 21, and 24 ng/mL. Following blocking and washing, anti-chicken IL-1b polyclonal antibody was added, plates were later incubated with detecting antibodies, and reactions developed with tetramethylbenzidine solution. A commercially available anti-chicken IL-1β (ChIL-1β) polyclonal antibody (pAb) cross-reacted with house finch plasma IL-1β as well as bacterially expressed recombinant house finch IL-1β (rHfIL-1β) in immunoblotting assays. In a direct ELISA system, rHfIL-1β could not be detected by an anti-ChIL-1β pAb when the antigen was coated with carbonate-bicarbonate buffer at 4°C overnight. However, rHfIL-1β was detected by the anti-ChIL-1β pAb when the antigen was coated using a dehydration method by heat (60°C). Using the developed direct ELISA for HfIL-1β with commercial anti-ChIL-1β pAb, we were able to measure plasma IL-1β levels from house finches. Based on high amino acid sequence homology, we hypothesized and demonstrated cross-reactivity of

  7. Direct currents produced by hf heating of plasma

    International Nuclear Information System (INIS)

    Klima, R.

    1974-01-01

    In addition to the well-known diffusion currents, toroidal direct currents arise in h.f. heated plasmas as a result of a momentum transfer from the h.f. field to plasma particles. The estimates of steady-state conditions are given for these currents. Particularly, the possibility of stationary operation of a Tokamak device is analyzed. (author)

  8. Lu-Hf and Sm-Nd garnet geochronology

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Scherer, Erik E.; Mezger, Klaus

    2013-01-01

    To investigate the systematics of the 176Lu–176Hf and 147Sm–143Nd garnet chronometers, we performed REE and isotope analyses on garnet crystals of different size (0.55–3.1 mm radius) from a single granulite specimen (Archean Pikwitonei Granulite Domain, Manitoba, Canada). The Lu–Hf dates are simi...

  9. Validation of Zr and Hf analysis contained on water phase using k_0-neutron activation analysis method

    International Nuclear Information System (INIS)

    Wisjachudin Faisa; Sutisna

    2010-01-01

    At conversion of Zr-sand to Zircon Oxide, the Hf content in product process should not be more than 100 ppm. While Zr and Hf are two elements that have a similar chemical property Hs, they are difficult to analyze by ordinary chemical analysis. One of reliable analytical method that can be used to quantify Zr and Hf is the instrumental neutron activation analysis. Related to this problem, a result of k_0-Instrumental Neutron Activation Analysis (k_0-INAA) on Zr and Hf (in aqueous phase) has been validated. A number of 200 µL SPEX Pure standard solution which have a concentration of 1 g/L pipeted into a cleaned micro vial, then dried at a temperature of 40°C for 24 hours. Samples, together with flux monitors, were irradiated simultaneously at 15 MW power (thermal neutron flux around 4.1 x 10"1"7n. m"-"2.s"-"1) for 30 minutes in the rabbit facility of GA. Siwabessy reactor. Counting of the irradiated sample have been done using a high resolution HPGe detector (FWHM = 1.9 keV at Eγ 1332.5 keV of "6"0Co,Peak to Compton ratio ~ 40). The analytical results showed a relative standard deviation (RSD) of Zr is 6.6 % with average uncertainty of 3.08 % and a detection limit of 0.1 mg, while RSD of Hf = 8.2 %, with average uncertainty of 8.04 % and a detection limit of 0.3 mg. Recovery obtained was 106,0 % and 96,0 % for Zr and Hf respectively. These results are relatively better compared to the previous result using the Standard Reference Material (SRM) 1633b Coal Fly Ash which have RSD Hf was 20.6 %. (author)

  10. High temperature X-ray diffraction studies on HfO2-Gd2O3 system

    International Nuclear Information System (INIS)

    Panneerselvam, G.; Antony, M.P.; Ananthasivan, K.; Joseph, M.

    2016-01-01

    High temperature X-ray diffraction (HTXRD) technique is an important experimental tool for measuring thermal expansion of materials of interest. A series of solid solutions containing GdO 1.5 in HfO 2 ,Hf 1-y Gd y )O 2 (y = 0.15, 0.2, 0.3, 0.41 and 0.505) were prepared by solid state method. Structural characterization and computation of lattice parameter was carried out by using room temperature X-ray diffraction measurements. The room temperature lattice parameter estimated for (Hf 1-y Gd y )O 2 (y=0.15, 0.2, 0.3, 0.41 and 0.505) are 0.51714 nm, 0.51929 nm, 0.52359nm, 0.52789nm and 0.53241 nm, respectively. Thermal expansion coefficients and percentage linear thermal expansion of the HfO 2 -Gd 2 O 3 solid solutions containing 20 and 41 mol% GdO 1.5 were determined using HTXRD in the temperature range 298 to 1673K. The mean linear thermal expansion coefficients of the solid solutions containing 20 and 41 mol. %Gd are 11.65 x 10 -6 K -1 and 12.07 x 10 -6 K -1 , respectively. (author)

  11. A new class of materials with promising thermoelectric properties: MNiSn (M=Ti, Zr, Hf)

    Energy Technology Data Exchange (ETDEWEB)

    Hohl, H; Ramirez, A P; Kaefer, W; Fess, K; Thurner, Ch; Kloc, Ch; Bucher, E

    1997-07-01

    TiNiSn, ZrNiSn and HfNiSn are members of a large group of intermetallic compounds which crystallize in the cubic MgAgAs-type structure. Polycrystalline samples of these compounds have been prepared and investigated for their thermoelectric properties. With thermopowers of about {minus}200 {micro}V/K and resistivities of a few m{Omega}cm, power factors S{sup 2}/{rho} as high as 38 {micro}W/K{sup 2}cm were obtained at 700 K. These remarkably high power factors are, however, accompanied by a thermal conductivity, solid solutions Zr{sub 1{minus}x}Hf{sub x}NiSn, Zr{sub 1{minus}x}Ti{sub x}NiSn, and Hf{prime}{sub 1{minus}x}Ti{sub x}NiSn were formed. The figure of merit of Zr{sub 0.5}Hf{sub 0.5}NiSn at 700 K (ZT = 0.41) exceeds the end members ZrNiSn (ZT = 0.26) and HfNiSn (ZT = 0.22).

  12. Determination of trace amount of titanium in 2.5% Nb-Zr alloy by anion exchange separation and sulfo salicylic acid photometry

    International Nuclear Information System (INIS)

    Sakai, Fumiaki; Wachi, Isamu; Tsuji, Nobuo; Satoh, Hitoshi

    1973-01-01

    A trace amount of Ti in 2.5% Nb-Zr alloy can be determined by a combined method of the characteristic anion exchange separation of Ti from Nb and the absorption photometry of Ti with sulfo salicylic acid. The alloy (1g) was dissolved in 5 ml of HF (1 + 1), and 5 ml of HNO 3 was added to them. The resultant 5M HF - 6M HNO 3 mixed acid solution was passed into an anion exchange resin column with 10 mm internal diameter and 100 mm high, at the rate of 1 to 2 ml/min. Niobium was adsorbed on to the column, through which Ti passed. The collected passing and washing solutions were converted into H 2 SO 4 medium by twice successive fuming treatments. The solution was transferred into a volumetric flask of 50 ml, and 10 ml of 10% sulfo salicylic acid in H 2 SO 4 was added. Diluting to a mark with H 2 SO 4 , the solution was allowed to stand for 15 min. Titanium was then determined by measuring absorption intensity at the wavelength of 410 mm. The influence of coexisting elements on the coloration of Ti and some adsorption conditions of Nb was experimentally investigated by using 95 Nb as a tracer. The experiment revealed that the removal of Nb is essential, and that higher HF concentration and lower HNO 3 concentration contribute to higher Nb adsorption. A variable rate type cockless column is useful for this routine analysis. The standard deviation and the coefficient of variation of analysis are 1.3 and 4.06% respectively for the concentration level of 32 ppm Ti (NZ-3). (Iwakiri, K.)

  13. Calculating the acidity of silanols and related oxyacids in aqueous solution

    Science.gov (United States)

    Tossell, John A.; Sahai, Nita

    2000-12-01

    Ab initio molecular orbital theory was used to calculate deprotonation energies and enthalpies (ΔE d, ΔH d) of oxyacid monomers and oligomers. Results were interpreted with reference to current phenomenological models for estimating metal-oxide surface acidities. The ultimate goal is to predict surface acidities using the ab initio method. We evaluated contributions to ΔE d and ΔH d from the electrostatic potential at the proton, electronic relaxation, geometric relaxation, solvation, and polymerization for the neutral-charge gas-phase molecules H 2O, CH 3OH, HCOOH, SiH 3OH, Si(OH) 4, Si 2O 7H 6, H 3PO 4, P 2O 7H 4, H 2SO 3, H 2SO 4, HOCl, HClO 4, Ge(OH) 4, As(OH) 3, and AsO(OH) 3. ΔE d, gas calculated at the modest 6-31G∗ HF of theory level correlates well with experimental pK a in solution, because hydration enthalpies for the acid anions (ΔH hyd, A-) are closely proportional to ΔE d, gas. That is, anion interaction energies with water in aqueous solution and with H + in the gas phase are closely correlated. Correction for differential hydration between an acid and its conjugate base permits generalization of the ΔE d, gas - pK a correlation to deprotonation reactions involving charged acids. Thus, stable protonated, neutral, and deprotonated species Si(OH) 3(OH 2) 1+, Si(OH) 40, Si(OH) 3O 1-, and Si(OH) 2O 22- have been characterized, and solution pK a's for Si(OH) 3(OH 2) 1+ and Si(OH) 3O 1- were estimated, assuming that the charged species (Si(OH) 3(OH 2) 1+, Si(OH) 3O -1) fit into the same ΔE d, gas - pK a correlation as do the neutral acids. The correlation yields a negative pK a (˜ -5) for Si(OH) 3(OH 2) +1. Calculated ΔE d, gas also correlates well with the degree of O under-bonding evaluated using Brown's bond-length based approach. ΔE d, gas increases along the series HClO 4 - Si(OH) 4 mainly because of increasingly negative potential at the site of the proton, not because of differing electronic or geometric relaxation energies. Thus, pK a

  14. Effect of Aging Temperature on Corrosion Behavior of Sintered 17-4 PH Stainless Steel in Dilute Sulfuric Acid Solution

    Science.gov (United States)

    Szewczyk-Nykiel, Aneta; Kazior, Jan

    2017-07-01

    The general corrosion behavior of sintered 17-4 PH stainless steel processed under different processing conditions in dilute sulfuric acid solution at 25 °C was studied by open-circuit potential measurement and potentiodynamic polarization technique. The corrosion resistance was evaluated based on electrochemical parameters, such as polarization resistance, corrosion potential, corrosion current density as well as corrosion rate. The results showed that the precipitation-hardening treatment could significantly improve the corrosion resistance of the sintered 17-4 PH stainless steel in studied environment. As far as the influence of aging temperature on corrosion behavior of the sintered 17-4 PH stainless steel is concerned, polarization resistance and corrosion rate are reduced with increasing aging temperature from 480 up to 500 °C regardless of the temperature of solution treatment. It can be concluded that the highest corrosion resistance in 0.5 M H2SO4 solution exhibits 17-4 PH after solution treatment at 1040 °C followed by aging at 480 °C.

  15. Phase and Microstructural Correlation of Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic Composites

    Directory of Open Access Journals (Sweden)

    Ambreen Nisar

    2017-07-01

    Full Text Available The refractory diborides (HfB2 and ZrB2 are considered as promising ultra-high temperature ceramic (UHTCs where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as the sintering aids and toughening agents in the spark plasma sintered (SPS HfB2-ZrB2 system. Herein, a novel equimolar composition of HfB2 and ZrB2 has shown to form a solid-solution which then allows compositional tailoring of mechanical properties (such as hardness, elastic modulus, and fracture toughness. The hardness of the processed composite is higher than the individual phase hardness up to 1.5 times, insinuating the synergy of SiC and CNT reinforcement in HfB2-ZrB2 composites. The enhanced fracture toughness of CNT reinforced composite (up to a 196% increment surpassing that of the parent materials (ZrB2/HfB2-SiC is attributed to the synergy of solid solution formation and enhanced densification (~99.5%. In addition, the reduction in the analytically quantified interfacial residual tensile stress with SiC and CNT reinforcements contribute to the enhancement in the fracture toughness of HfB2-ZrB2-SiC-CNT composites, mandatory for aerospace applications.

  16. The Reaction Mechanism and Rate Constants in the Radiolysis of Fe2+-Cu2+ Solutions

    DEFF Research Database (Denmark)

    Bjergbakke, Erling; Sehested, Knud; Rasmussen, O. Lang

    1976-01-01

    Pulse radiolysis and gamma radiolysis have been used to study the reaction mechanism in the radiolysis of aqueous solutions of Fe2+ and Cu2+. A reaction scheme has been developed and confirmed by computation of the corresponding complete set of differential equations. The rate constants for some ...... 10^{8}$ and $1.3\\times 10^{8}\\ {\\rm mol}^{-1}\\ {\\rm sec}^{-1}$ in pH 2.1 H2 SO4 and HClO4, respectively.......Pulse radiolysis and gamma radiolysis have been used to study the reaction mechanism in the radiolysis of aqueous solutions of Fe2+ and Cu2+. A reaction scheme has been developed and confirmed by computation of the corresponding complete set of differential equations. The rate constants for some...... of the reactions have been determined at different pH's. $k_{{\\rm Cu}^{+}+{\\rm O}_{2}}=4.6\\times 10^{5}$ and $1.0\\times 10^{6}\\ {\\rm mol}^{-1}\\ {\\rm sec}^{-1}$, $k_{{\\rm Cu}^{+}+{\\rm Fe}^{3+}}=5.5\\times 10^{6}$ and $1.3\\times 10^{7}\\ {\\rm mol}^{-1}\\ {\\rm sec}^{-1}$, $k_{{\\rm Cu}({\\rm III)}+{\\rm Fe}^{2+}}=3.3\\times...

  17. An Exact Method to Determine the Conductivity of Aqueous Solutions in Acid-Base Titrations

    Directory of Open Access Journals (Sweden)

    Norma Rodríguez-Laguna

    2015-01-01

    Full Text Available Several works in the literature show that it is possible to establish the analytic equations to estimate the volume V of a strong base or a strong acid (Vb and Va, resp. being added to a solution of a substance or a mix of substances during an acid-base titration, as well as the equations to estimate the first derivative of the titration plot dpH/dV, and algebraic expressions to determine the buffer β capacity with dilution βdil. This treatment allows establishing the conditions of thermodynamic equilibria for all species within a system containing a mix of species from one or from various polyacid systems. The present work shows that it is possible to determine exactly the electric conductivity of aqueous solutions for these Brønsted acid-base titrations, because the functional relation between this property and the composition of the system in equilibrium is well known; this is achieved using the equivalent conductivity λi values of each of the ions present in a given system. The model employed for the present work confirms the experimental outcomes with the H2SO4, B(OH3, CH3COOH, and H3PO4 aqueous solutions’ titration.

  18. Optimizing the recovery of copper from electroplating rinse bath solution by hollow fiber membrane.

    Science.gov (United States)

    Oskay, Kürşad Oğuz; Kul, Mehmet

    2015-01-01

    This study aimed to recover and remove copper from industrial model wastewater solution by non-dispersive solvent extraction (NDSX). Two mathematical models were developed to simulate the performance of an integrated extraction-stripping process, based on the use of hollow fiber contactors using the response surface method. The models allow one to predict the time dependent efficiencies of the two phases involved in individual extraction or stripping processes. The optimal recovery efficiency parameters were determined as 227 g/L of H2SO4 concentration, 1.22 feed/strip ratio, 450 mL/min flow rate (115.9 cm/min. flow velocity) and 15 volume % LIX 84-I concentration in 270 min by central composite design (CCD). At these optimum conditions, the experimental value of recovery efficiency was 95.88%, which was in close agreement with the 97.75% efficiency value predicted by the model. At the end of the process, almost all the copper in the model wastewater solution was removed and recovered as CuSO4.5H2O salt, which can be reused in the copper electroplating industry.

  19. Fruit waste adsorbent for ammonia nitrogen removal from synthetic solution: Isotherms and kinetics

    Science.gov (United States)

    Zahrim, AY; Lija, Y.; Ricky, L. N. S.; Azreen, I.

    2016-06-01

    In this study, four types of watermelon rind (WR) adsorbents; fresh WR, modified WR with sodium hydroxide (NaOH), potassium hydroxide (KOH) and sulphuric acid (H2SO4) were used as a potential low-cost adsorbent to remove NH3-N from solution. The adsorption data were fitted with the adsorption isotherm and kinetic models to predict the mechanisms and kinetic characteristics of the adsorption process. The equilibrium data agreed well with Langmuir isotherm model with highest correlation (R2=1.00). As for kinetic modelling, the adsorption process follows pseudo-second order for all four types of adsorbents which has R2 value of 1.0 and calculated adsorption capacity, Qe of 1.2148mg/g. The calculated Qe for pseudo-second order has the smallest difference with the experimental Qe and thus suggest that this adsorption process is mainly governed by chemical process involving cations sharing or exchange between WR adsorbent and NH3-N in the solution.

  20. Process Simulation Analysis of HF Stripping

    Directory of Open Access Journals (Sweden)

    Thaer A. Abdulla

    2015-02-01

    Full Text Available    HYSYS process simulator is used for the analysis of existing HF stripping column in LAB plant (Arab Detergent Company, Baiji-Iraq. Simulated column performance and profiles curves are constructed. The variables considered are the thermodynamic model option, bottom temperature, feed temperature, and column profiles for the temperature, vapor flow rate, liquid flow rate and composition. The five thermodynamic models options used (Margules, UNIQUAC, van laar, Antoine, and Zudkevitch-Joffee, affecting the results within (0.1-58% variation for the most cases.        The simulated results show that about 4% of paraffin (C10 & C11 presents at the top stream, which may cause a problem in the LAB production plant. The major variations were noticed for the total top vapor flow rate with bottom temperature and with feed composition. The column profiles maintain fairly constants from tray 5 to tray 18. The study gives evidence about a successful simulation with HYSYS because the results correspond with the real plant operation data.

  1. Grindability of cast Ti-Hf alloys.

    Science.gov (United States)

    Kikuchi, Masafumi; Takahashi, Masatoshi; Sato, Hideki; Okuno, Osamu; Nunn, Martha E; Okabe, Toru

    2006-04-01

    As part of our systematic studies characterizing the properties of titanium alloys, we investigated the grindability of a series of cast Ti-Hf alloys. Alloy buttons with hafnium concentrations up to 40 mass% were made using an argon-arc melting furnace. Each button was cast into a magnesia-based mold using a dental titanium casting machine; three specimens were made for each metal. Prior to testing, the hardened surface layer was removed. The specimens were ground at five different speeds for 1 min at 0.98 N using a carborundum wheel on an electric dental handpiece. Grindability was evaluated as the volume of metal removed per minute (grinding rate) and the volume ratio of metal removed compared to the wheel material lost (grinding ratio). The data were analyzed using ANOVA. A trend of increasing grindability was found with increasing amounts of hafnium, although there was no statistical difference in the grindability with increasing hafnium contents. We also found that hafnium may be used to harden or strengthen titanium without deteriorating the grindability.

  2. Time variations of hf induced plasma waves

    International Nuclear Information System (INIS)

    Showen, R.L.

    1976-01-01

    Intense plasma waves are generated by an HF pump wave in an ionospheric heating experiment at the Arecibo Observatory. These plasma waves can be observed as enhancements to the ion and plasma lines of the incoherent backscatter echo. The enhancements can be three or four orders of magnitude more intense than the unenhanced lines, and tend to fluctuate wildly. Both the purely growing and the decay mode parametric instabilities are present. When the pump wave is turned on abruptly the enhancements develop in time in a repeatable manner. A rather remarkable feature on time scales of seconds is an overshoot in instability power. These overshoots occur frequently but not universally and last for 1 to 6 seconds. They can have a magnitude from ten to hundreds of times the average instability level. Field aligned irregularities may be the cause of the overshoots. The overshoots appear definitely related to an unusually rapid rise in measured electron temperature that cannot be understood in terms of ohmic energy deposition. On time scales of milliseconds there is a ''mini-overshoot'' before the growth of the instability to a large value. The spectral details also change in a striking manner. The instabilities can first be detected 2 to 4 msec after the pump wave turn-on. The decay mode is present as well as a broad featureless ''noise bump'', which partially sharpens into a line as time progresses. These changes of the spectra in time seem to run counter to the currently accepted theories of plasma wave saturation

  3. Behaviour at the indicator scale of the elements Zr, Hf and 104, Nb,Ta and Pa (105) in very complexation media; Comportement a l`echelle des indicateurs des elements Zr, Hf, et 104, Nb, Ta, et Pa (105) en milieux tres complexants

    Energy Technology Data Exchange (ETDEWEB)

    Monroy Guzman, F. [Institut de Physique Nucleaire, CNRS - IN2P3 Universite Paris Sud, 91406 Orsay Cedex (France)

    1997-12-31

    In order to determine the chemical properties of the trans-actinide elements of Z = 104 and 105 in aqueous solutions we studied their behaviour to ion exchange resin in different complex media. Due to the very short lifetimes (some tens of seconds) et to the low yield of these elements (a few atoms per irradiation hour) only very fast radiochemical techniques can be used. These severe constraints impose comparative studies of these elements with their most likely homologues to be carried out. The corresponding homologues were the elements of group 4 (Zr and Hf) for the element 104 and the elements of group 5 (Nb and Ta) and also Pa for the element 105. The complexation properties of the elements at indicator scale were determined in the media of HF, NH{sub 4}/HClO{sub 4}, NH{sub 4}SCN/HClO{sub 4}, NH{sub 4}SCN/HF and HCl/HF by ion exchange chromatography. The studies in fluorides media allowed us to identify the complexes in solution and to explain the shape of the experimentally observed sorption curves. The decrease of sorption for higher acid concentration in case of HF/HCl medium was interpreted by formation of chloro-fluoro-complexes. In case of the mixture NH{sub 4}SCN/HF, the particularly pronounced anti-synergic effects were observed and discussed. At the same time studies of the Hf and Ta short-lived isotopes were carried out by means of the RACHEL facility operating by the Orsay Tandem accelerator. These realistic simulations allowed optimization of different production, transportation and separation stages of the trans-actinide elements. The two experiments of 104 element production showed that this element forms in HF very stable anionic complexes similarly to its homologues Zr and Hf. (authors). 181 refs.

  4. Behaviour at the indicator scale of the elements Zr, Hf and 104, Nb,Ta and Pa (105) in very complexation media; Comportement a l`echelle des indicateurs des elements Zr, Hf, et 104, Nb, Ta, et Pa (105) en milieux tres complexants

    Energy Technology Data Exchange (ETDEWEB)

    Monroy Guzman, F [Institut de Physique Nucleaire, CNRS - IN2P3 Universite Paris Sud, 91406 Orsay Cedex (France)

    1998-12-31

    In order to determine the chemical properties of the trans-actinide elements of Z = 104 and 105 in aqueous solutions we studied their behaviour to ion exchange resin in different complex media. Due to the very short lifetimes (some tens of seconds) et to the low yield of these elements (a few atoms per irradiation hour) only very fast radiochemical techniques can be used. These severe constraints impose comparative studies of these elements with their most likely homologues to be carried out. The corresponding homologues were the elements of group 4 (Zr and Hf) for the element 104 and the elements of group 5 (Nb and Ta) and also Pa for the element 105. The complexation properties of the elements at indicator scale were determined in the media of HF, NH{sub 4}/HClO{sub 4}, NH{sub 4}SCN/HClO{sub 4}, NH{sub 4}SCN/HF and HCl/HF by ion exchange chromatography. The studies in fluorides media allowed us to identify the complexes in solution and to explain the shape of the experimentally observed sorption curves. The decrease of sorption for higher acid concentration in case of HF/HCl medium was interpreted by formation of chloro-fluoro-complexes. In case of the mixture NH{sub 4}SCN/HF, the particularly pronounced anti-synergic effects were observed and discussed. At the same time studies of the Hf and Ta short-lived isotopes were carried out by means of the RACHEL facility operating by the Orsay Tandem accelerator. These realistic simulations allowed optimization of different production, transportation and separation stages of the trans-actinide elements. The two experiments of 104 element production showed that this element forms in HF very stable anionic complexes similarly to its homologues Zr and Hf. (authors). 181 refs.

  5. Metallization on FDM Parts Using the Chemical Deposition Technique

    Directory of Open Access Journals (Sweden)

    Azhar Equbal

    2014-08-01

    Full Text Available Metallization of ABS (acrylonitrile-butadiene-styrene parts has been studied on flat part surfaces. These parts are fabricated on an FDM (fused deposition modeling machine using the layer-wise deposition principle using ABS as a part material. Electroless copper deposition on ABS parts was performed using two different surface preparation processes, namely ABS parts prepared using chromic acid for etching and ABS parts prepared using a solution mixture of sulphuric acid and hydrogen peroxide (H2SO4/H2O2 for etching. After surface preparations using these routes, copper (Cu is deposited electrolessly using four different acidic baths. The acidic baths used are 5 wt% CuSO4 (copper sulfate with 15 wt% of individual acids, namely HF (hydrofluoric acid, H2SO4 (sulphuric acid, H3PO4 (phosphoric acid and CH3COOH (acetic acid. Cu deposition under different acidic baths used for both the routes is presented and compared based on their electrical performance, scanning electron microscopy (SEM and energy dispersive X-ray spectrometry (EDS. The result shows that chromic acid etched samples show better electrical performance and Cu deposition in comparison to samples etched via H2SO4/H2O2.

  6. TaxHf1−xB2–SiC multiphase oxidation protective coating for SiC-coated carbon/carbon composites

    International Nuclear Information System (INIS)

    Ren, Xuanru; Li, Hejun; Fu, Qiangang; Li, Kezhi

    2014-01-01

    Highlights: • Ta x Hf 1−x B 2 –SiC coating was prepared on SiC coated C/C by in-situ reaction method. • TaB 2 and HfB 2 were introduced in the form of solid solution Ta x Hf 1−x B 2 . • The coating could protect C/C for 1480 h with only 0.57% mass loss at 1773 K in air. • Oxidation layer consists of out Ta–Si–O compound layer and inner SiO 2 glass layer. • Ta–Si–O compound silicate layer presents a better stability than SiO 2 glass layer. - Abstract: A Ta x Hf 1−x B 2 –SiC coating was prepared by in-situ reaction method on SiC coated C/C composites. Ta x Hf 1−x B 2 phase is the form of solid solution between TaB 2 and HfB 2 . Isothermal oxidation behavior at 1773 K and ablation behavior of the coated C/C were tested. Ta x Hf 1−x B 2 –SiC/SiC coating could protect the C/C from oxidation at 1773 K for 1480 h and ablation above 2200 K for 40 s. During oxidation, oxides of Ta and Hf atoms exist as “pinning phases” in the compound glass layer consisted of outer Ta–Si–O compound silicate layer and inner SiO 2 glass layer, which was responsible for the excellent oxidation resistance

  7. Remoção de níquel(II de soluções aquosas pela biomassa Sargassum filipendula em múltiplos ciclos de sorção-dessorção = Removal of nickel (II from aqueous solutions by Sargassum filipendula biomass in multiple cycles of sorption-desorption

    Directory of Open Access Journals (Sweden)

    Araceli Aparecida Seolatto

    2009-01-01

    Full Text Available Foi estudado o desempenho da alga marinha Sargassum filipendula na remoção de níquel de uma solução de concentração de 50 mg L-1 em pH 3,5, em colunas de leito fixo que operam em ciclos de adsorção/dessorção. Foram testados dois sistemas de eluição; oprimeiro operou com a passagem direta e o segundo com a recirculação do eluente. Em seguida, foram realizados dez ciclos consecutivos de sorção-dessorção em duas colunas de leito fixo, uma regenerada com o eluente H2SO4 (0,1 M e outra com MgSO4/H2SO4 (pH 3, em sistema de recirculação do eluente. As etapas de sorção e dessorção foram realizadas em 30 e 2h, respectivamente, representando 20 dias de uso contínuo da biomassa. Foi observada alta quantidade recuperada de níquel nas etapas de eluição (aproximadamente 95%. Ao finaldo décimo ciclo, verificou-se que a alga Sargassum filipendula continuava apresentando valores elevados da capacidade de remoção de níquel da solução, mostrando-se como alternativa eficiente de tratamento de águas residuárias contendo metais. A regeneração dabiomassa apresentou baixo custo, além de ter facilitado o processo de tratamento que dispensou trocas sucessivas da biomassa.The behavior of seaweed Sargassum filipendula during a removal of nickel from a 50 mg L-1 aqueous solution at pH 3.5 in fixed-bed columns operating in adsorption/desorption cycles was studied. Twoelution systems were tested: the first one operating with the direct passage of eluant, and the second one with the solution recycle. Then, ten consecutive sorption-desorption cycles were investigated in two packed-bed columns; the first column was regenerated with H2SO4 (0.1 M, and the second one with MgSO4/H2SO4 (3.5% in pH 3 in an eluant recycle system. The sorption and desorption stages were carried out for about 30 and 2h, respectively, representing 20 days of continuous use of the biomass. A high quantity of recovered nickelwas observed in the elution stages

  8. The magnetic properties of $^{\\rm 177}$Hf and $^{\\rm 180}$Hf in the strong coupling deformed model

    OpenAIRE

    Muto, S.; Stone, N. J.; Bingham, C. R.; Stone, J. R.; Walker, P. M.; Audi, G.; Gaulard, C.; Köster, U.; Nikolov, J.; Nishimura, K.; Ohtsubo, T.; Podolyak, Z.; Risegari, L.; Simpson, G. S.; Veskovic, M.

    2014-01-01

    This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2$^-$, 51.4 m, 2740 keV state in $^{\\rm 177}$Hf and the 8$^-$, 5.5 h, 1142 keV state in $^{\\rm 180}$Hf by the method of on-line nuclear orientation. Also included are results on the angular distributions of gamma transitions in the decay of the $^{\\rm 177}$Hf isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2$^+$, 1.1 s, isomer at 1315 keV ...

  9. Low-Frequency Waves in HF Heating of the Ionosphere

    Science.gov (United States)

    Sharma, A. S.; Eliasson, B.; Milikh, G. M.; Najmi, A.; Papadopoulos, K.; Shao, X.; Vartanyan, A.

    2016-02-01

    Ionospheric heating experiments have enabled an exploration of the ionosphere as a large-scale natural laboratory for the study of many plasma processes. These experiments inject high-frequency (HF) radio waves using high-power transmitters and an array of ground- and space-based diagnostics. This chapter discusses the excitation and propagation of low-frequency waves in HF heating of the ionosphere. The theoretical aspects and the associated models and simulations, and the results from experiments, mostly from the HAARP facility, are presented together to provide a comprehensive interpretation of the relevant plasma processes. The chapter presents the plasma model of the ionosphere for describing the physical processes during HF heating, the numerical code, and the simulations of the excitation of low-frequency waves by HF heating. It then gives the simulations of the high-latitude ionosphere and mid-latitude ionosphere. The chapter also briefly discusses the role of kinetic processes associated with wave generation.

  10. Theoretical Assessment of 178m2Hf De-Excitation

    Energy Technology Data Exchange (ETDEWEB)

    Hartouni, E P; Chen, M; Descalle, M A; Escher, J E; Loshak, A; Navratil, P; Ormand, W E; Pruet, J; Thompson, I J; Wang, T F

    2008-10-06

    This document contains a comprehensive literature review in support of the theoretical assessment of the {sup 178m2}Hf de-excitation, as well as a rigorous description of controlled energy release from an isomeric nuclear state.

  11. HF Surface Wave Radar Operation in Adverse Conditions

    National Research Council Canada - National Science Library

    Ponsford, Anthony M; Dizaji, Reza M; McKerracher, Richard

    2005-01-01

    ...) system based on HF Surface Wave Radar (HFSWR). the primary objective behind the programme was to demonstrate the capability of HFSWR to continuously detect and track surface targets (ships and icebergs...

  12. HF band filter bank multi-carrier spread spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Laraway, Stephen Andrew; Moradi, Hussein; Farhang-Boroujeny, Behrouz

    2015-10-01

    Abstract—This paper describes modifications to the filter bank multicarrier spread spectrum (FB-MC-SS) system, that was presented in [1] and [2], to enable transmission of this waveform in the HF skywave channel. FB-MC-SS is well suited for the HF channel because it performs well in channels with frequency selective fading and interference. This paper describes new algorithms for packet detection, timing recovery and equalization that are suitable for the HF channel. Also, an algorithm for optimizing the peak to average power ratio (PAPR) of the FBMC- SS waveform is presented. Application of this algorithm results in a waveform with low PAPR. Simulation results using a wide band HF channel model demonstrate the robustness of this system over a wide range of delay and Doppler spreads.

  13. HF-voltage testing of accelerating system functional model

    International Nuclear Information System (INIS)

    Gladkov, A.V.; Stepanov, V.B.

    1989-01-01

    Owing to ambiguity in interpreting the notion of the electron strength of the operating HF device in an acceleator a technique of measurements and result processing, based on statistical analysis of the data is suggested. Experimental testing on electric strength of structures with HF focusing was carried out using a bench in the form of a cylindrical vacuum container inside which a double H-resonator with HF quadrupole electrodes without surface modulation was installed. The dependences obtained permit to evaluate the bahaviour of the HF device from the viewpoint of electric strength and radiation hazard for the whole range of possible values of voltage on the basis of data on the frequency of breakdowns and radiation situation only in one experimental point. 12 refs.; 8 figs

  14. Integrated magnetics design for HF-link power converters

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, Michael A.E.

    2005-07-01

    This paper deals with the design of integrated magnetics for HF-link converters, where the two integrated magnetic components on the same core do not necessarily belong to the same voltage loop. Depending on the specific HF-link converter topology, the proposed integrated magnetics can either alleviate the derivation of independent auxiliary supply voltages from the main transformer or integrate other magnetic structures, thus saving board space and cutting costs. (au)

  15. Large Magnetic Anisotropy in HfMnP

    Science.gov (United States)

    Parker, David; Lamichhane, Tej; Taufour, Valentin; Masters, Morgan; Thimmaiah, Srinivasa; Bud'Ko, Ser'gey; Canfield, Paul

    We present a theoretical and experimental study of two little-studied manganese phosphide ferromagnets, HfMnP and ZrMnP, with Curie temperatures above room temperature. We find an anisotropy field in HfMnP approaching 10 T - larger than that of the permanent magnet workhorse NdFeB magnets. From theory we determine the source of this anisotropy. Our results show the potential of 3d-element-based magnetic materials for magnetic applications.

  16. Thermoelectric properties of doped BaHfO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Dixit, Chandra Kr., E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Dr. Shakuntala Misra National Rehabilitation University, Lucknow-229001, U.P India (India); Bhamu, K. C. [Department of Physics, Goa University, Goa-403 206 (India); Sharma, Ramesh, E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Feroze Gandhi Institute of Engineering & Technology, Raebareli-229001, U.P India (India)

    2016-05-06

    We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO{sub 3} by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO{sub 3} doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO{sub 3} is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO{sub 3} is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

  17. The isobutylene-isobutane alkylation process in liquid HF revisited.

    Science.gov (United States)

    Esteves, P M; Araújo, C L; Horta, B A C; Alvarez, L J; Zicovich-Wilson, C M; Ramírez-Solís, A

    2005-07-07

    Details on the mechanism of HF catalyzed isobutylene-isobutane alkylation were investigated. On the basis of available experimental data and high-level quantum chemical calculations, a detailed reaction mechanism is proposed taking into account solvation effects of the medium. On the basis of our computational results, we explain why the density of the liquid media and stirring rates are the most important parameters to achieve maximum yield of alkylate, in agreement with experimental findings. The ab initio Car-Parrinello molecular dynamics calculations show that isobutylene is irreversibly protonated in the liquid HF medium at higher densities, leading to the ion pair formation, which is shown to be a minimum on the potential energy surface after optimization using periodic boundary conditions. The HF medium solvates preferentially the fluoride anion, which is found as solvated [FHF](-) or solvated F(-.)(HF)(3). On the other hand, the tert-butyl cation is weakly solvated, where the closest HF molecules appear at a distance of about 2.9 Angstrom with the fluorine termination of an HF chain.

  18. Solid phase crystallisation of HfO2 thin films

    International Nuclear Information System (INIS)

    Modreanu, M.; Sancho-Parramon, J.; O'Connell, D.; Justice, J.; Durand, O.; Servet, B.

    2005-01-01

    In this paper, we report on the solid phase crystallisation of carbon-free HfO 2 thin films deposited by plasma ion assisted deposition (PIAD). After deposition, the HfO 2 films were annealed in N 2 ambient for 3 h at 350, 550 and 750 deg. C. Several characterisation techniques including X-ray reflectometry (XRR), X-ray diffraction (XRD), spectroscopic ellipsometry (SE) and atomic force microscopy (AFM) were used for the physical characterisation of as-deposited and annealed HfO 2 . XRD has revealed that the as-deposited HfO 2 film is in an amorphous-like state with only traces of crystalline phase and that the annealed films are in a highly crystalline state. These results are in good agreement with the SE results showing an increase of refractive index by increasing the annealing temperature. XRR results show a significant density gradient over the as-deposited film thickness, which is characteristic of the PIAD method. The AFM measurements show that the HfO 2 layers have a smooth surface even after annealing at 750 deg. C. The present study demonstrates that the solid phase crystallisation of HfO 2 PIAD thin films starts at a temperature as low as 550 deg. C

  19. Sequential sputtered Co-HfO{sub 2} granular films

    Energy Technology Data Exchange (ETDEWEB)

    Chadha, M.; Ng, V.

    2017-03-15

    A systematic study of magnetic, magneto-transport and micro-structural properties of Co-HfO{sub 2} granular films fabricated by sequential sputtering is presented. We demonstrate reduction in ferromagnetic-oxide formation by using HfO{sub 2} as the insulting matrix. Microstructure evaluation of the films showed that the film structure consisted of discrete hcp-Co grains embedded in HfO{sub 2} matrix. Films with varying compositions were prepared and their macroscopic properties were studied. We correlate the variation in these properties to the variation in film microstructure. Our study shows that Co-HfO{sub 2} films with reduced cobalt oxide and varying properties can be prepared using sequential sputtering technique. - Highlights: • Co-HfO{sub 2} granular films were prepared using sequential sputtering. • A reduction in ferromagnetic-oxide formation is observed. • Co-HfO{sub 2} films display superparamagnetism and tunnelling magneto-resistance. • Varying macroscopic properties were achieved by changing film composition. • Applications can be found in moderate MR sensors and high –frequency RF devices.

  20. Titrimetric determination of Zr, Hf, Sn, Ta and rare earths in binary oxide systems

    International Nuclear Information System (INIS)

    Flyantikova, G.V.; Chekirda, T.N.; Lasovskaya, O.N.; Migun, N.P.

    1989-01-01

    Proximate method of titrimetric determination of oxides of Zr(4), Hf(4), Sn(4), Ta(5) and rare earths (La, Lu, Nd, Eu, Yb, Y) in binary systems (BS) with high accuracy was developed. A study was made on conditions of decomposition and dissolution of BS by means of their treatment by the mixture of solutions of concentrated sulfuric acid and ammonium sulfate during 2h boiling eith successive complexonometric determination of their components by direct EDTA titration in the presence of xylenol orange. The relative standard deviation when titrating 0.3-9.7mg oxides in BS does not exceed 0.02

  1. The influence of thermal treatment on the phase development in HfO2-Al2O3 and ZrO2-Al2O3 systems

    International Nuclear Information System (INIS)

    Stefanic, G.; Music, S.; Trojko, R.

    2005-01-01

    Amorphous precursors of HfO 2 -AlO 1.5 and ZrO 2 -AlO 1.5 systems covering the whole concentration range were co-precipitated from aqueous solutions of the corresponding salts. The thermal behaviour of the amorphous precursors was examined by differential thermal analysis, X-ray powder diffraction (XRD), laser Raman spectroscopy and scanning electron microscopy. The crystallization temperature of both systems increased with increase in the AlO 1.5 content, from 530 to 940 deg. C in the HfO 2 -AlO 1.5 system, and from 405 to 915 deg. C in the ZrO 2 -AlO 1.5 system. The results of phase analysis indicate an extended capability for the incorporation of Al 3+ ions in the metastable HfO 2 - and ZrO 2 -type solid solutions obtained after crystallization of amorphous co-gels. Precise determination of lattice parameters, performed using whole-powder-pattern decomposition method, showed that the axial ratio c f /a f in the ZrO 2 - and HfO 2 -type solid solutions with 10 mol% or more of Al 3+ approach 1. The tetragonal symmetry of these samples, as determined by laser Raman spectroscopy, was attributed to the displacement of the oxygen sublattice from the ideal fluorite positions. It was found that the lattice parameters of the ZrO 2 -type solid solutions decreased with increasing Al 3+ content up to ∼10 mol%, whereas above 10 mol%, further increase of the Al 3+ content has very small influence on the unit-cell volume of both HfO 2 - and ZrO 2 -type solid solutions. The reason for such behaviour was discussed. The solubility of Hf 4+ and Zr 4+ ions in the aluminium oxides lattice appeared to be negligible

  2. Reconciliation of the excess 176Hf conundrum in meteorites: Recent disturbances of the Lu-Hf and Sm-Nd isotope systematics

    Science.gov (United States)

    Bast, Rebecca; Scherer, Erik E.; Sprung, Peter; Mezger, Klaus; Fischer-Gödde, Mario; Taetz, Stephan; Böhnke, Mischa; Schmid-Beurmann, Hinrich; Münker, Carsten; Kleine, Thorsten; Srinivasan, Gopalan

    2017-09-01

    The long-lived 176Lu-176Hf and 147Sm-143Nd radioisotope systems are commonly used chronometers, but when applied to meteorites, they can reveal disturbances. Specifically, Lu-Hf isochrons commonly yield dates up to ∼300 Myr older than the solar system and varying initial 176Hf/177Hf values. We investigated this problem by attempting to construct mineral and whole rock isochrons for eucrites and angrites. Meteorites from different parent bodies exhibit similar disturbance features suggesting that a common process is responsible. Minerals scatter away from isochron regressions for both meteorite classes, with low-Hf phases such as plagioclase and olivine typically being most displaced above (or left of) reference isochrons. Relatively Hf-rich pyroxene is less disturbed but still to the point of steepening Lu-Hf errorchrons. Using our Lu-Hf and Sm-Nd data, we tested various Hf and Lu redistribution scenarios and found that decoupling of Lu/Hf from 176Hf/177Hf must postdate the accumulation of significant radiogenic 176Hf. Therefore early irradiation or diffusion cannot explain the excess 176Hf. Instead, disturbed meteorite isochrons are more likely caused by terrestrial weathering, contamination, or common laboratory procedures. The partial dissolution of phosphate minerals may predominantly remove rare earth elements including Lu, leaving relatively immobile and radiogenic Hf behind. Robust Lu-Hf (and improved Sm-Nd) meteorite geochronology will require the development of chemical or physical methods for removing unsupported radiogenic Hf and silicate-hosted terrestrial contaminants without disturbing parent-daughter ratios.

  3. Tracking magmatic processes through Zr/Hf ratios in rocks and Hf and Ti zoning in zircons: An example from the Spirit Mountain batholith, Nevada

    Science.gov (United States)

    Lowery, Claiborne L.E.; Miller, C.F.; Walker, B.A.; Wooden, J.L.; Mazdab, F.K.; Bea, F.

    2006-01-01

    Zirconium and Hf are nearly identical geochemically, and therefore most of the crust maintains near-chondritic Zr/Hf ratios of ???35-40. By contrast, many high-silica rhyolites and granites have anomalously low Zr/Hf (15-30). As zircon is the primary reservoir for both Zr and Hf and preferentially incorporates Zr, crystallization of zircon controls Zr/ Hf, imprinting low Zr/Hf on coexisting melt. Thus, low Zr/Hf is a unique fingerprint of effective magmatic fractionation in the crust. Age and compositional zonation in zircons themselves provide a record of the thermal and compositional histories of magmatic systems. High Hf (low Zr/ Hf) in zircon zones demonstrates growth from fractionated melt, and Ti provides an estimate of temperature of crystallization (TTiZ) (Watson and Harrison, 2005). Whole-rock Zr/Hf and zircon zonation in the Spirit Mountain batholith, Nevada, document repeated fractionation and thermal fluctuations. Ratios of Zr/Hf are ???30-40 for cumulates and 18-30 for high-SiO2 granites. In zircons, Hf (and U) are inversely correlated with Ti, and concentrations indicate large fluctuations in melt composition and TTiZ (>100??C) for individual zircons. Such variations are consistent with field relations and ion-probe zircon geochronology that indicate a >1 million year history of repeated replenishment, fractionation, and extraction of melt from crystal mush to form the low Zr/Hf high-SiO2 zone. ?? 2006 The Mineralogical Society.

  4. Ge interactions on HfO2 surfaces and kinetically driven patterning of Ge nanocrystals on HfO2

    International Nuclear Information System (INIS)

    Stanley, Scott K.; Joshi, Sachin V.; Banerjee, Sanjay K.; Ekerdt, John G.

    2006-01-01

    Germanium interactions are studied on HfO 2 surfaces, which are prepared through physical vapor deposition (PVD) and by atomic layer deposition. X-ray photoelectron spectroscopy and temperature-programed desorption are used to follow the reactions of germanium on HfO 2 . Germanium chemical vapor deposition at 870 K on HfO 2 produces a GeO x adhesion layer, followed by growth of semiconducting Ge 0 . PVD of 0.7 ML Ge (accomplished by thermally cracking GeH 4 over a hot filament) also produces an initial GeO x layer, which is stable up to 800 K. PVD above 2.0 ML deposits semiconducting Ge 0 . Temperature programed desorption experiments of ∼1.0 ML Ge from HfO 2 at 400-1100 K show GeH 4 desorption below 600 K and GeO desorption above 850 K. These results are compared to Ge on SiO 2 where GeO desorption is seen at 550 K. Exploiting the different reactivity of Ge on HfO 2 and SiO 2 allows a kinetically driven patterning scheme for high-density Ge nanoparticle growth on HfO 2 surfaces that is demonstrated

  5. Relationship between CCR and NT-proBNP in Chinese HF patients, and their correlations with severity of HF.

    Science.gov (United States)

    Lu, Zhigang; Wang, Bo; Wang, Yunliang; Qian, Xueqing; Zheng, Wei; Wei, Meng

    2014-01-01

    To evaluate the relationship between creatinine clearance rate (CCR) and the level of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in heart failure (HF) patients and their correlations with HF severity. Two hundred and one Chinese patients were grouped according to the New York Heart Association (NYHA) classification as NYHA 1-2 and 3-4 groups and 135 cases out of heart failure patients as control group. The following variables were compared among these three groups: age, sex, body mass index (BMI), smoking status, hypertension, diabetes, NT-proBNP, creatinine (Cr), uric acid (UA), left ventricular end-diastolic diameter (LVEDD), and CCR. The biomarkers of NT-proBNP, Cr, UA, LVEDD, and CCR varied significantly in the three groups, and these variables were positively correlated with the NHYA classification. The levels of NT-proBNP and CCR were closely related to the occurrence of HF and were independent risk factors for HF. At the same time, there was a significant negative correlation between the levels of NT-proBNP and CCR. The area under the receiver operating characteristic curve suggested that the NT-proBNP and CCR have high accuracy for diagnosis of HF and have clinical diagnostic value. NT-proBNP and CCR may be important biomarkers in evaluating the severity of HF.

  6. Joint Efforts Towards European HF Radar Integration

    Science.gov (United States)

    Rubio, A.; Mader, J.; Griffa, A.; Mantovani, C.; Corgnati, L.; Novellino, A.; Schulz-Stellenfleth, J.; Quentin, C.; Wyatt, L.; Ruiz, M. I.; Lorente, P.; Hartnett, M.; Gorringe, P.

    2016-12-01

    During the past two years, significant steps have been made in Europe for achieving the needed accessibility to High Frequency Radar (HFR) data for a pan-European use. Since 2015, EuroGOOS Ocean Observing Task Teams (TT), such as HFR TT, are operational networks of observing platforms. The main goal is on the harmonization of systems requirements, systems design, data quality, improvement and proof of the readiness and standardization of HFR data access and tools. Particular attention is being paid by HFR TT to converge from different projects and programs toward those common objectives. First, JERICO-NEXT (Joint European Research Infrastructure network for Coastal Observatory - Novel European eXpertise for coastal observaTories, H2020 2015 Programme) will contribute on describing the status of the European network, on seeking harmonization through exchange of best practices and standardization, on developing and giving access to quality control procedures and new products, and finally on demonstrating the use of such technology in the general scientific strategy focused by the Coastal Observatory. Then, EMODnet (European Marine Observation and Data Network) Physics started to assemble HF radar metadata and data products within Europe in a uniform way. This long term program is providing a combined array of services and functionalities to users for obtaining free of charge data, meta-data and data products on the physical conditions of European sea basins and oceans. Additionally, the Copernicus Marine Environment Monitoring Service (CMEMS) delivers from 2015 a core information service to any user related to 4 areas of benefits: Maritime Safety, Coastal and Marine Environment, Marine Resources, and Weather, Seasonal Forecasting and Climate activities. INCREASE (Innovation and Networking for the integration of Coastal Radars into EuropeAn marine SErvices - CMEMS Service Evolution 2016) will set the necessary developments towards the integration of existing European

  7. Low modulus Ti–Nb–Hf alloy for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    González, M., E-mail: Marta.Gonzalez.Colominas@upc.edu [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Materials Science, Elisava Escola Superior de Disseny i Enginyeria de Barcelona, La Rambla 30-32, 08002 Barcelona (Spain); Peña, J. [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Materials Science, Elisava Escola Superior de Disseny i Enginyeria de Barcelona, La Rambla 30-32, 08002 Barcelona (Spain); Gil, F.J.; Manero, J.M. [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Ciber-BBN (Spain)

    2014-09-01

    β-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37 °C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The stress–strain curves showed the lowest elastic modulus (42 GPa) in the cold worked alloy and high tensile strength, similar to that of Ti6Al4V. The new alloy exhibited better corrosion resistance in terms of open circuit potential (E{sub OCP}), but was similar in terms of corrosion current density (i{sub CORR}) compared to Ti grade II. Cytotoxicity studies revealed that the chemical composition of the alloy does not induce cytotoxic activity. Cell studies in the new alloy showed a lower adhesion and a higher proliferation compared to Ti grade II presenting, therefore, mechanical features similar to those of human cortical bone and, simultaneously, a good cell response. - Highlights: • Presents low elastic modulus and high strength and elastic deformability. • Exhibits good biocompatibility in terms of cytotoxicity and cell response. • Corrosion resistance of this alloy is good, similar to that of Ti grade II. • Potential candidate for implants used to substitute failed hard tissue.

  8. Inhibition of Mild Steel Corrosion in Sulfuric Acid Solution by New Schiff Base

    Directory of Open Access Journals (Sweden)

    Ahmed A. Al-Amiery

    2014-01-01

    Full Text Available The efficiency of Schiff base derived from 4-aminoantipyrine, namely 2-(1,5-dimethyl-4-(2-methylbenzylideneamino-2-phenyl-1H-pyrazol-3(2H-ylidene hydrazinecarbothioamide as a corrosion inhibitor on mild steel in 1.0 M H2SO4 was investigated using electrochemical impedance spectroscopy (EIS, potentiodynamic polarization (PD and electrochemical frequently modulation (EFM in addition to the adsorption isotherm, corrosion kinetic parameters and scanning electron microscopy (SEM. The results showed that this inhibitor behaved as a good corrosion inhibitor, even at low concentration, with a mean efficiency of 93% and, also, a reduction of the inhibition efficiency as the solution temperature increases. A polarization technique and EIS were tested for different concentrations and different temperatures to reveal that this compound is adsorbed on the mild steel, therefore blocking the active sites, and the adsorption follows the Langmuir adsorption isotherm model. The excellent inhibition effectiveness of 2-(1,5-dimethyl-4-(2-methylbenzylideneamino-2-phenyl-1H-pyrazol-3(2H-ylidenehydrazinecarbothioamide was also verified by scanning electron microscope (SEM.

  9. MoS₂ nanocube structures as catalysts for electrochemical H₂ evolution from acidic aqueous solutions.

    Science.gov (United States)

    Maijenburg, A Wouter; Regis, Morrisa; Hattori, Azusa N; Tanaka, Hidekazu; Choi, Kyoung-Shin; ten Elshof, Johan E

    2014-02-12

    Core-shell PMMA-Au nanocube structures made by a combination of nanoimprint lithography and sidewall deposition were used as template for electrodeposition of MoS2, Ni, and Pt. Linear sweep voltammetry experiments obtained in an aqueous solution containing 0.29 M H2SO4 (pH 0.24) showed that the onset potential of the core-shell-shell PMMA-Au-MoS2 nanocube electrode for the hydrogen evolution reaction (HER) was shifted to the positive direction (i.e., requiring a lower overpotential) by 20-40 mV compared to planar MoS2 films. This indicates that the nanocube electrodes have a significantly increased HER activity, which is probably because of a higher density of catalytically active edge sites available at the nanocube surface. It was also found that the HER activity initially increased with increasing MoS2 deposition time, but decreased after deposition for 60 min because the edges of the nanocubes became rounded, thereby decreasing the number of active edge sites. By depositing Ni and Pt on top of PMMA-Au nanocubes, it was shown that this method can also be used for the synthesis of nanocube structures with varying compositions.

  10. Inhibition of Mild Steel Corrosion in Sulfuric Acid Solution by New Schiff Base

    Science.gov (United States)

    Al-Amiery, Ahmed A.; Kadhum, Abdul Amir H.; Kadihum, Abdulhadi; Mohamad, Abu Bakar; How, Chong K.; Junaedi, Sutiana

    2014-01-01

    The efficiency of Schiff base derived from 4-aminoantipyrine, namely 2-(1,5-dimethyl-4-(2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-ylidene) hydrazinecarbothioamide as a corrosion inhibitor on mild steel in 1.0 M H2SO4 was investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PD) and electrochemical frequently modulation (EFM) in addition to the adsorption isotherm, corrosion kinetic parameters and scanning electron microscopy (SEM). The results showed that this inhibitor behaved as a good corrosion inhibitor, even at low concentration, with a mean efficiency of 93% and, also, a reduction of the inhibition efficiency as the solution temperature increases. A polarization technique and EIS were tested for different concentrations and different temperatures to reveal that this compound is adsorbed on the mild steel, therefore blocking the active sites, and the adsorption follows the Langmuir adsorption isotherm model. The excellent inhibition effectiveness of 2-(1,5-dimethyl-4-(2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-ylidene)hydrazinecarbothioamide was also verified by scanning electron microscope (SEM). PMID:28788488

  11. Determination of uranium in uranium metal, uranium oxides, and uranyl nitrate solutions by potentiometric titration

    International Nuclear Information System (INIS)

    Tucker, H.L.; McElhaney, R.J.

    1983-01-01

    A simple, fast method for the determination of uranium in uranium metal, uranium oxides, and uranyl nitrate solutions has been adapted from the Davies-Gray volumetric method to meet the needs of Y-12. One-gram duplicate aliquots of uranium metal or uranium oxide are dissolved in 1:1 HNO 3 and concentrated H 2 SO 4 to sulfur trioxide fumes, and then diluted to 100-mL volume. Duplicate aliquots are then weighed for analysis. For uranyl nitrate samples, duplicate aliquots containing between 50 and 150 mg of U are weighed and analyzed directly. The weighed aliquot is transferred to a Berzelius beaker; 1.5 M sulfamic acid is added, followed in order by concentrated phosphoric acid, 1 M ferrous sulfate, and (after a 30-second interval) the oxidizing reagent. After a timed 3-minute waiting period, 100 mL of the 0.1% vanadyl sulfate-sulfuric acid mixture is added. The sample is then titrated past its endpoint with standard potassium dichromate, and the endpoint is determined by second derivative techniques on a mV/weight basis

  12. Electropolishing of AISI-304 stainless steel using an oxidizing solution originally used for electrochemical coloration

    International Nuclear Information System (INIS)

    Andrade, Leonardo S.; Xavier, Sandro C.; Rocha-Filho, Romeu C.; Bocchi, Nerilso; Biaggio, Sonia R.

    2005-01-01

    Chemical polishing or electropolishing, instead of mechanical polishing, are recommended for the attainment of metallic surface polishes without the introduction of contaminants or tensions in the surface layers of the metal. The fundamental difference between the chemical and electrochemical polishing processes is that in the latter anodic currents/potentials are used to help in the dissolution and passivation of the metal. In this paper, the use of an oxidizing electrolytic solution (2.5 mol L -1 CrO 3 + 5.0 mol L -1 H 2 SO 4 ) originally employed in electrochemical coloration processes is reported for the electropolishing of AISI-314 stainless steel. Parameters involved in this electropolishing process, such as temperature, current density and time, were optimized so as to attain the best possible results evaluated by the obtained surface brightness measured by reflectance spectra. Surface analyses by scanning electron microscopy allowed a clear correlation between obtained brightness and surface smoothing. The best conditions obtained for the electropolishing process are: temperature of 45 deg. C, electrolysis time of 10 min and current density of around 25 A dm -2 . It should be pointed out that an electropolishing process signature (periodic oscillations of the cell potential) was established; this may be an important tool for optimizing and monitoring electropolishing processes

  13. Heterogeneous ice nucleation in aqueous solutions: the role of water activity.

    Science.gov (United States)

    Zobrist, B; Marcolli, C; Peter, T; Koop, T

    2008-05-01

    Heterogeneous ice nucleation experiments have been performed with four different ice nuclei (IN), namely nonadecanol, silica, silver iodide and Arizona test dust. All IN are either immersed in the droplets or located at the droplets surface. The IN were exposed to various aqueous solutions, which consist of (NH4)2SO4, H2SO4, MgCl2, NaCl, LiCl, Ca(NO3)2, K2CO3, CH3COONa, ethylene glycol, glycerol, malonic acid, PEG300 or a NaCl/malonic acid mixture. Freezing was studied using a differential scanning calorimeter and a cold finger cell. The results show that the heterogeneous ice freezing temperatures decrease with increasing solute concentration; however, the magnitude of this effect is solute dependent. In contrast, when the results are analyzed in terms of the solution water activity a very consistent behavior emerges: heterogeneous ice nucleation temperatures for all four IN converge each onto a single line, irrespective of the nature of the solute. We find that a constant offset with respect to the ice melting point curve, Deltaaw,het, can describe the observed freezing temperatures for each IN. Such a behavior is well-known for homogeneous ice nucleation from supercooled liquid droplets and has led to the development of water-activity-based ice nucleation theory. The large variety of investigated solutes together with different general types of ice nuclei studied (monolayers, ionic crystals, covalently bound network-forming compounds, and a mixture of chemically different crystallites) underlines the general applicability of water-activity-based ice nucleation theory also for heterogeneous ice nucleation in the immersion mode. Finally, the ice nucleation efficiencies of the various IN, as well as the atmospheric implication of the developed parametrization are discussed.

  14. A comparative electrochemical study of electrosorbed 2- and 4 ...

    Indian Academy of Sciences (India)

    mercaptopyridine (2 Mpy) and 4-mercaptopyridine (4 Mpy) dissolved in either water or an aqueous solution of 0.1 M H2SO4 on a polycrystalline gold electrode has been investigated in an aqueous electrolyte solution (0.5 M H2SO4) using cyclic ...

  15. Coulomb-nuclear interference measurements of 168Yb, 176Hf, 178Hf, and 180Hf and lifetime measurements in 186Hg

    International Nuclear Information System (INIS)

    Nettles, W.G.

    1979-01-01

    Alpha scattering measurements were performed at center-of-mass energies near the Coulomb barrier. These energies allow for nuclear as well as pure Coulomb forces to play a significant role in the excitation process. The interference of these two forces is very sensitive to the sign of the E4 ground-state moment, whereas pure Coulomb excitation is not. Systematics of the E4 moments of the rare earth mass region indicate a transition in the magnitude and sign of the reduced matrix element of the M(E4) operator between 0 + and 4 + states from small and positive to large and negative between Yb and W. Previous Coulomb-nuclear interference measurements show that this reduced matrix element for 180 Hf is large and negative. The present results agree with that conclusion. It is also shown that the above reduced matrix element for 178 Hf, like that of 180 Hf, is large and negative. The small and positive moment (matrix element) for 168 Yb is seen to be consistent with the experimental data. No conclusions are drawn for the E4 moment in 176 Hf. The measurement of nuclear lifetimes shorter than 500 ps requires the use of plastic scintilltor detectors. These detectors, however have very poor energy resolution. A system is described that uses plastic scintillators with a magnetic lens spectrometer for energy selection. The system was used to measure the lifetime of the 522-keV 0 + sate in 186 Hf. A data analysis method using higher-order distribution moments is also presented

  16. Surface characteristics of hydroxyapatite-coated layer prepared on nanotubular Ti–35Ta–xHf alloys by EB-PVD

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Yong-Hoon [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Moon, Byung-Hak [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, Columbus, OH (United States)

    2013-12-31

    In this study, we investigated the surface characteristics of hydroxyapatite (HA)-coated layers prepared by electron-beam physical vapor deposition (EB-PVD) on nanotubular Ti–35Ta–xHf alloys (x = 3, 7, and 15 wt.%). Ti–35Ta–xHf alloys were first prepared by arc melting. Formation of a nanotube structure on these alloys was achieved by an electrochemical method in 1 M H{sub 3}PO{sub 4} + 0.8 wt.% NaF electrolytes. The HA coatings were then deposited on the nanotubular surface by an EB-PVD method. The surface characteristics were analyzed by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD). The electrochemical behavior was examined using a potentiodynamic polarization test in 0.9% NaCl solution. The Ti–35Ta–xHf alloys had an equiaxed grain structure with α″ + β phases, and the α″ phase disappeared with increases in Hf content. The Ti–35Ta–15Hf alloy showed higher β-phase peak intensity in the XRD patterns than that for the lower Hf-content alloys. A highly ordered nanotubular oxide layer was formed on the Ti–35Ta–15Hf alloy, and the tube length depended on Hf content. The HA coating surface formed at traces of the nanotubular titanium oxide layer and completely covered the tips of the nanotubes with a cluster shape. From the potentiodynamic polarization tests, the incorporation of Hf element and formation of the nanotubular structure were the main factors for achieving lower current density. In particular, the surface of the HA coating on the nanotubular structure exhibited higher corrosion resistance than that of the nanotubular titanium oxide structure without an HA coating. - Highlights: • Hydroxyapatite (HA) was coated on nanotubular Ti–35Ta–xHf alloys, using EB-PVD. • Increasing the Hf content reduced the relative proportion of α″ martensite to β-Ti in the microstructures. • The detailed nanotubular structure formed by anodization depended on alloy composition

  17. Surface characteristics of hydroxyapatite-coated layer prepared on nanotubular Ti–35Ta–xHf alloys by EB-PVD

    International Nuclear Information System (INIS)

    Jeong, Yong-Hoon; Moon, Byung-Hak; Choe, Han-Cheol; Brantley, William A.

    2013-01-01

    In this study, we investigated the surface characteristics of hydroxyapatite (HA)-coated layers prepared by electron-beam physical vapor deposition (EB-PVD) on nanotubular Ti–35Ta–xHf alloys (x = 3, 7, and 15 wt.%). Ti–35Ta–xHf alloys were first prepared by arc melting. Formation of a nanotube structure on these alloys was achieved by an electrochemical method in 1 M H 3 PO 4 + 0.8 wt.% NaF electrolytes. The HA coatings were then deposited on the nanotubular surface by an EB-PVD method. The surface characteristics were analyzed by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD). The electrochemical behavior was examined using a potentiodynamic polarization test in 0.9% NaCl solution. The Ti–35Ta–xHf alloys had an equiaxed grain structure with α″ + β phases, and the α″ phase disappeared with increases in Hf content. The Ti–35Ta–15Hf alloy showed higher β-phase peak intensity in the XRD patterns than that for the lower Hf-content alloys. A highly ordered nanotubular oxide layer was formed on the Ti–35Ta–15Hf alloy, and the tube length depended on Hf content. The HA coating surface formed at traces of the nanotubular titanium oxide layer and completely covered the tips of the nanotubes with a cluster shape. From the potentiodynamic polarization tests, the incorporation of Hf element and formation of the nanotubular structure were the main factors for achieving lower current density. In particular, the surface of the HA coating on the nanotubular structure exhibited higher corrosion resistance than that of the nanotubular titanium oxide structure without an HA coating. - Highlights: • Hydroxyapatite (HA) was coated on nanotubular Ti–35Ta–xHf alloys, using EB-PVD. • Increasing the Hf content reduced the relative proportion of α″ martensite to β-Ti in the microstructures. • The detailed nanotubular structure formed by anodization depended on alloy composition. • The

  18. [Effect of a multifunctional instrument (HF scissors) in parotis surgery].

    Science.gov (United States)

    Strauss, G; Schaller, S; Gollnick, I

    2014-03-01

    Lateral parotidectomy is a demanding surgical procedure and requires a large number of instruments with a high frequency (HF) of alternating. Many functions, such as preparing, spreading, coagulating and cutting could be combined by using scissors with an integrated function of bipolar coagulation. This study has targeted an investigation of technical application, influence on surgery time, frequency of HF application and change of instruments. In the period between 01 April 2011 and 30 September 2012 (18 months) 35 procedures of lateral parotidectomy in 35 patients were investigated. In all cases lateral parotidectomy was carried out with a similar technique (modified extracapsular preparation). Workflow data were used from a control group in the period between 01 January 2009 and 31 December 2010 (24 months). The following parameters from both groups were documented and evaluated: incision-suture times (subdivided into nine sections of the procedure), change of instruments, period of application for HF function and early facial nerve function (6 h and 6 days after surgery according to House-Brackmann). Additionally, in the HF+ group a questionnaire that facilitated subjective evaluation of instruments was analyzed. It was possible to perform the surgery in both groups with neither technical nor surgical intraoperative complications. Incision-suture times showed an average reduction of 31.6 min (34.8 %) in the HF+ group. There was a reduction in the change of instruments compared to a conventional group (CONV) by up to 62.7 %. With the deployment of HF scissors there was a clear increase in the use of HF surgery by more than 100 % when comparing incision-suture times. Evaluation of both groups according to House-Brackmann showed a similar postoperative facial nerve function. The surgeons involved were of the opinion that in all 35 surgeries with HF scissors the intervention was easier and more comfortable. The use of HF scissors is appropriate for parotid gland

  19. The extraction of zirconium (IV) from sulfuric acid solutions with high-molecular weight quaternary ammonium compound

    International Nuclear Information System (INIS)

    Sato, Taichi; Watanabe, Hiroshi

    1982-01-01

    The extraction of zirconium sulfate in aqueous sulfuric acid solutions with trioctylmethylammonium chloride (Aliquat-336; R 3 R'NCl) in organic solvents has been investigated under different conditions. In addition, the organic phases extracted sulfuric acid and zirconium sulfate were examined by IR and NMR spectroscopies. It has been found that Aliquat-336 extracts zirconium (IV) from sulfuric acid solutions according to the following ion-exchange reactions. i) The extraction of sulfuric acid is at first carried out through the equilibria, SO 4 2 - (aq) + 2R 3 R'NCl(org) reversible (R 3 R'N) 2 SO 4 (org) + 2Cl - (aq), (R 3 R'N) 2 SO 4 (org) + H + (aq) + HSO 4- (aq) reversible 2R 3 R'NHSO 4 (org). ii) The extraction of zirconium is expressed as the equilibrium reaction, Zr(SO 4 ) 3 2 - (aq) + 2xR 3 R'NHSO 4 (org) + (1-x)(R 3 R'N) 2 SO 4 (org) reversible (R 3 R'N) 2 [Zr(SO 4 ) 3 ](org) + xH 2 SO 4 (aq) + SO 4 2 - (aq), x = [R 3 R'NHSO 4 ]/(2[(R 3 R'N) 2 SO 4 ] + [R 3 R'NHSO 4 ]). Moreover, the hydrolyzed species (R 3 R'N)[ZrO(OH)(SO 4 )] is formed when zirconium is further extracted in an organic phase. (author)

  20. Error analysis of equilibrium studies for the almond shell activated carbon adsorption of Cr(VI) from aqueous solutions

    International Nuclear Information System (INIS)

    Demirbas, E.; Kobya, M.; Konukman, A.E.S.

    2008-01-01

    In this study, the preparation of activated carbon from almond shell with H 2 SO 4 activation and its ability to remove toxic hexavalent chromium from aqueous solutions are reported. The influences of several operating parameters such as pH, particle size and temperature on the adsorption capacity were investigated. Adsorption of Cr(VI) is found to be highly pH, particle size and temperature dependent. Four adsorption isotherm models namely, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich were used to analyze the equilibrium data. The Langmuir isotherm provided the best correlation for Cr(VI) onto the almond shell activated carbon (ASC). Adsorption capacity was calculated from the Langmuir isotherm as 190.3 mg/g at 323 K. Thermodynamic parameters were evaluated and the adsorption was endothermic showing monolayer adsorption of Cr(VI). Five error functions were used to treat the equilibrium data using non-linear optimization techniques for evaluating the fit of the isotherm equations. The highest correlation for the isotherm equations in this system was obtained for the Freundlich isotherm. ASC is found to be inexpensive and effective adsorbent for removal of Cr(VI) from aqueous solutions

  1. Draft revision of human factors guideline HF-010

    International Nuclear Information System (INIS)

    Lee, Hyun Chul; Lee, Yong Hee; Oh, In Seok; Lee, Jung Woon; Cha, Woo Chang; Lee, Dhong Ha

    2003-05-01

    The Application of Human Factors to the design of Man-Machine Interfaces System(MMIS) in the nuclear power plant is essential to the safety and productivity of the nuclear power plants, human factors standards and guidelines as well as human factors analysis methods and experiments are weightily used to the design application. A Korean engineering company has developed a human factors engineering guideline, so-call HF-010, and has used it for human factors design, however the revision of HF-010 is necessary owing to lack of the contents related to the advanced MMI(Man-Machine Interfaces). As the results of the reviews of HF-010, it is found out that the revision of Section 9. Computer Displays of HF-010 is urgent, thus the revision was drafted on the basis of integrated human factors design guidelines for VDT, human factors design guidelines for PMAS SPADES display, human factors design guidelines for PMAS alarm display, and human factors design guidelines for electronic displays developed by the surveillance and operation support project of KOICS. The draft revision of HF-010 Section 9 proposed in this report can be utilized for the human factors design of the advanced MMI, and the high practical usability of the draft can be kept up through the continuous revision according to the advancement of digital technology

  2. Centrifugal stretching along the ground state band of 168Hf

    International Nuclear Information System (INIS)

    Costin, A.; Pietralla, N.; Reese, M.; Moeller, O.; Ai, H.; Casten, R. F.; Heinz, A.; McCutchan, E. A.; Meyer, D. A.; Qian, J.; Werner, V.; Dusling, K.; Fitzpatrick, C. R.; Guerdal, G.; Petkov, P.; Rainovski, G.

    2009-01-01

    The lifetimes of the J π =4 + , 6 + , 8 + , and 10 + levels along the ground state band in 168 Hf were measured by means of the recoil distance Doppler shift (RDDS) method using the New Yale Plunger Device (NYPD) and the SPEEDY detection array at Wright Nuclear Structure Laboratory of Yale University. Excited states in 168 Hf were populated using the 124 Sn( 48 Ti,4n) fusion evaporation reaction. The new lifetime values are sufficiently precise to clearly prove the increase of quadrupole deformation as a function of angular momentum in the deformed nucleus 168 Hf. The data agree with the predictions from the geometrical confined β-soft (CBS) rotor model that involves centrifugal stretching in a soft potential

  3. Determining characteristics of HF communications links using SuperDARN

    Directory of Open Access Journals (Sweden)

    J. M. Hughes

    2002-07-01

    Full Text Available Space weather effects can strongly influence high-frequency (HF communications by changing the ionospheric environment through which the radio waves propagate. Since many systems utilize HF communications, the ability to make real-time assessments of propagation conditions is an important part of space weather monitoring systems. In this paper, we present new techniques for measuring high-latitude HF communications link parameters using data from SuperDARN radars. These techniques use ground-scatter returns to define the variation in skip distance with frequency. From these data, the maximum usable frequency (MUF as a function of range is determined and ionospheric critical frequencies are estimated. These calculations are made in near-real-time and the results are made available on the World Wide Web. F-region critical frequencies calculated using this method show good agreement with ionosonde data.Key words. Ionosphere (active experiments; instruments and techniques – Radio science (ionospheric propagation

  4. Determining characteristics of HF communications links using SuperDARN

    Directory of Open Access Journals (Sweden)

    J. M. Hughes

    Full Text Available Space weather effects can strongly influence high-frequency (HF communications by changing the ionospheric environment through which the radio waves propagate. Since many systems utilize HF communications, the ability to make real-time assessments of propagation conditions is an important part of space weather monitoring systems. In this paper, we present new techniques for measuring high-latitude HF communications link parameters using data from SuperDARN radars. These techniques use ground-scatter returns to define the variation in skip distance with frequency. From these data, the maximum usable frequency (MUF as a function of range is determined and ionospheric critical frequencies are estimated. These calculations are made in near-real-time and the results are made available on the World Wide Web. F-region critical frequencies calculated using this method show good agreement with ionosonde data.

    Key words. Ionosphere (active experiments; instruments and techniques – Radio science (ionospheric propagation

  5. Densification and properties of HfB2 based materials

    International Nuclear Information System (INIS)

    Sonber, J.K.; Ch Murthy, T.S.R.; Bedse, R.D.; Subramanian, C.; Kumar, Sunil; Fotedar, R.K.; Krishnamurthy, N.; Suri, A.K.

    2011-01-01

    This paper presents the results of investigation carried out on densification and properties of HfB 2 based materials. Densification study of HfB 2 with and without sinter additive was carried out by hot pressing. TiSi 2 and CrSi 2 were used as sinter additive. Monolithic HfB 2 was densified to only 80%ρ th at 1850 deg C with a pressure of 35 MPa. Addition of 10 wt% TiSi 2 resulted in a density of 95% TD at a relatively low temperature of 1650 deg C and a low pressure of 20 MPa. Addition of 10% CrSi 2 resulted in a density of 99% TD at the same operating conditions. All the samples were characterized by SEM/EDS and mechanical property measurement. (author)

  6. HF-START: A Regional Radio Propagation Simulator

    Science.gov (United States)

    Hozumi, K.; Maruyama, T.; Saito, S.; Nakata, H.; Rougerie, S.; Yokoyama, T.; Jin, H.; Tsugawa, T.; Ishii, M.

    2017-12-01

    HF-START (HF Simulator Targeting for All-users' Regional Telecommunications) is a user-friendly simulator developed to meet the needs of space weather users. Prediction of communications failure due to space weather disturbances is of high priority. Space weather users from various backgrounds with high economic impact, i.e. airlines, telecommunication companies, GPS-related companies, insurance companies, international amateur radio union, etc., recently increase. Space weather information provided by Space Weather Information Center of NICT is, however, too professional to be understood and effectively used by the users. To overcome this issue, I try to translate the research level data to the user level data based on users' needs and provide an immediate usable data. HF-START is positioned to be a space weather product out of laboratory based truly on users' needs. It is originally for radio waves in HF band (3-30 MHz) but higher frequencies up to L band are planned to be covered. Regional ionospheric data in Japan and southeast Asia are employed as a reflector of skywave mode propagation. GAIA (Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy) model will be used as ionospheric input for global simulation. To evaluate HF-START, an evaluation campaign for Japan region will be launched in coming months. If the campaign successes, it will be expanded to southeast Asia region as well. The final goal of HF-START is to provide the near-realtime necessary radio parameters as well as the warning message of radio communications failure to the radio and space weather users.

  7. Oxidation behavior of Hf-modified platinum aluminide coatings during thermal cycling

    Directory of Open Access Journals (Sweden)

    Liya Ye

    2018-02-01

    Full Text Available Platinum aluminide coatings with different Hf contents were fabricated by using HfCl4. The oxidation kinetics and the rumpling behavior of oxide scale were investigated. After thermal cycling, the coating with 0.46 wt% Hf showed least weight gain. With the increase of Hf content, rumpling extent of the scale decreased. Meanwhile, HfO2 preferentially formed in the scale resulting in the increase of scale thickness. The oxidation of excessive Hf even caused the spallation of the scale. The results in the present study indicate that although Hf plays an important role in decreasing rumpling extent of TGO, the oxidation of Hf decreases the adhesion of the scale. Keywords: Pt-Al coating, Hf, Oxidation, Rumpling

  8. HF-induced airglow at magnetic zenith: theoretical considerations

    Directory of Open Access Journals (Sweden)

    E. V. Mishin

    2005-01-01

    Full Text Available Observations of airglow at 630nm (red line and 557.7nm (green line during HF modification experiments at the High Frequency Active Auroral Research Program (HAARP heating facility are analyzed. We propose a theoretical framework for understanding the generation of Langmuir and ion acoustic waves during magnetic zenith injections. We show that observations of HF-induced airglow in an underdense ionosphere as well as a decrease in the height of the emitting volume are consistent with this scenario.

  9. Influence of rotation on multiphoton processes in HF

    International Nuclear Information System (INIS)

    Broeckhove, J.; Feyen, B.; Van Leuven, P.

    1994-01-01

    In this contribution, the authors are concerned with the role of rotational motion in multiphoton processes induced by a laser field of high intensity. The authors use the pseudospectral split operator method for the propagation of the quantum wave-function. The rotation is treated by decomposition of the HF wave-function in its angular momentum components

  10. lambda-3, Sandia's 100-J HF laser system

    International Nuclear Information System (INIS)

    Klein, R.A.

    1979-09-01

    Sandia's lambda-geometry intermediate electron-beam-initiated HF amplifier is described in sufficient detail such that a similar system could be designed, constructed and characterized. Items included are the design of the laser cell, magnetic field design and measurements, electron-beam calorimetry, and typical laser results

  11. Multiple excitation modes in 163Hf

    DEFF Research Database (Denmark)

    Yadav, Rachita; Ma, J.C.; Marsh, J.C.

    2014-01-01

    Excited states of Hf163 were populated using the Zr94(Ge74,5n) reaction and the decay γ rays were measured with the Gammasphere spectrometer. Two previously known bands were extended to higher spins, and nine new bands were identified. In addition to bands associated with three- and five-quasiparticle...

  12. COPD predicts mortality in HF: the Norwegian Heart Failure Registry.

    Science.gov (United States)

    De Blois, Jonathan; Simard, Serge; Atar, Dan; Agewall, Stefan

    2010-03-01

    Chronic obstructive pulmonary disease (COPD) and chronic heart failure (HF) are common clinical conditions that share tobacco as a risk factor. Our aim was to evaluate the prognostic impact of COPD on HF patients. The Norwegian Heart Failure Registry was used. The study included 4132 HF patients (COPD, n = 699) from 22 hospitals (mean follow-up, 13.3 months). COPD patients were older, more often smokers and diabetics, less often on beta-blockers and had a higher heart rate. They were more often in New York Heart Association (NYHA) Class III or IV (COPD, 63%; no COPD, 51%), although left ventricular ejection fraction (LVEF) distribution was similar. COPD independently predicted death (adjusted hazard ratio [HR], 1.188; 95% CI: 1.015 to 1.391; P = 0.03) along with age, creatinine, NYHA Class III/IV (HR, 1.464; 95% CI: 1.286 to 1.667) and diabetes. beta-blockers at baseline were associated with improved survival in patients with LVEF < or =40% independently of COPD. COPD is associated with a poorer survival in HF patients. COPD patients are overrated in terms of NYHA class in comparison with patients with similar LVEF. Nonetheless, NYHA class remains the strongest predictor of death in these patients. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  13. Research of HF and HV circuit with Pspice

    International Nuclear Information System (INIS)

    Guo Jianjiang; Li Quanfeng; Zheng Shuxin; Li Wenjun; Tang Chuanxiang

    2005-01-01

    Transferring HF and HV pulse with 3 kinds of components is discussed. Terminal volt waves was got using the soft of Pspice when transmission line is matching of load in 3 kinds of condition. It is proved by experiments that the results got from Pspice have important values to improve experiment circuit. (authors)

  14. Electrochemical investigation of the surface energy: Effect of the HF concentration on electroless silver deposition onto p-Si (1 1 1)

    International Nuclear Information System (INIS)

    Ye Weichun; Chang Yanlong; Ma Chuanli; Jia Bingyu; Cao Guiyan; Wang Chunming

    2007-01-01

    Electroless silver deposition onto p-silicon (1 1 1) from 0.005 mol l -1 AgNO 3 solutions with different HF concentration was investigated by using an electrochemical direct current polarization method and open circuit potential-time (Ocp-t) technique. The fact that three-dimensional (3D) growth of silver onto silicon is favored with increasing the HF concentration was ascribed to the drop of the surface energy and approved by electrochemical direct current polarization, Ocp-t technique and atomic force microscopy (AFM). The drop slope of open-circuit potential, K -ΔE(OCP)/t , was educed from the mixed-potential theory. K -ΔE(OCP)/t as well as the deposition rate determined by an inductively coupled plasma atomic emission spectrometry (ICP-AES), increased with the HF concentration, yet was not a linear function. Results were explained by the stress generation and relaxation mechanisms

  15. Enhanced corrosion resistance of stainless steel type 316 in sulphuric acid solution using eco-friendly waste product

    Science.gov (United States)

    Sanni, O.; Popoola, A. P. I.; Fayomi, O. S. I.

    2018-06-01

    Literature has shown that different organic compounds are effective corrosion inhibitors for metal in acidic environments. Such compounds usually contain oxygen, nitrogen or sulphur and function through adsorption on the metal surface, thereby creating a barrier for corrosion attack. Unfortunately, these organic compounds are toxic, scarce and expensive. Therefore, plants, natural product and natural oils have been posed as cheap, environmentally acceptable, abundant, readily available and effective molecules having low environmental impact. The corrosion resistance of austenitic stainless steel Type 316 in the presence of eco-friendly waste product was studied using weight loss and potentiodynamic polarization techniques in 0.5 M H2SO4. The corrosion rate and corrosion potential of the steel was significantly altered by the studied inhibitor. Results show that increase in concentration of the inhibitor hinders the formation of the passive film. Experimental observation shows that its pitting potential depends on the concentration of the inhibitor in the acid solution due to adsorption of anions at the metal film interface. The presence of egg shell powder had a strong influence on the corrosion resistance of stainless steel Type 316 with highest inhibition efficiency of 94.74% from weight loss analysis, this is as a result of electrochemical action and inhibition of the steel by the ionized molecules of the inhibiting compound which influenced the mechanism of the redox reactions responsible for corrosion and surface deterioration. Inhibitor adsorption fits the Langmuir isotherm model. The two methods employed for the corrosion assessment were in good agreement.

  16. HF Radar observations of the Dardanelles outflow current in North Eastern Aegean using validated WERA HF radar data

    Directory of Open Access Journals (Sweden)

    Z. KOKKINI

    2014-12-01

    Full Text Available A two-site WERA HF radar station was installed in November 2009 at the eastern coast of Lemnos Island in North Aegean Sea, aiming to monitor the surface inflow of Black Sea waters exiting from the Dardanelles Strait, as well as to constitute a coastal management tool for incidents of oil-pollution or save-and-rescue operations. Strong interference by foreign transmissions is a source of noise deteriorating the quality of the backscattered signal, thus significantly reducing the HF radar’s effective data return rate. In order to ameliorate this problem, further quality-control and data gap interpolating procedures have been developed and applied, to be used in addition to the procedures incorporated and used by the manufacturer’s signal processing software. The second-level processing involves traditional despiking in the temporal domain, preceding Empirical Orthogonal Function analysis. The latter is used not only to filter high-frequency noise but also to fill data gaps in time and space. The data reconstruction procedure has been assessed via comparison of (a HF radial with CODE-type drifter radial velocities as well as (b HF-derived virtual drifter tracks with actual drifter tracks. The main circulation features and their variability, as revealed by the reconstructed fields, are presented.

  17. Nanopore fabricated in pyramidal HfO2 film by dielectric breakdown method

    Science.gov (United States)

    Wang, Yifan; Chen, Qi; Deng, Tao; Liu, Zewen

    2017-10-01

    The dielectric breakdown method provides an innovative solution to fabricate solid-state nanopores on insulating films. A nanopore generation event via this method is considered to be caused by random charged traps (i.e., structural defects) and high electric fields in the membrane. Thus, the position and number of nanopores on planar films prepared by the dielectric breakdown method is hard to control. In this paper, we propose to fabricate nanopores on pyramidal HfO2 films (10-nm and 15-nm-thick) to improve the ability to control the location and number during the fabrication process. Since the electric field intensity gets enhanced at the corners of the pyramid-shaped film, the probability of nanopore occurrence at vertex and edge areas increases. This priority of appearance provides us chance to control the location and number of nanopores by monitoring a sudden irreversible discrete increase in current. The experimental results showed that the probability of nanopore occurrence decreases in an order from the vertex area, the edge area to the side face area. The sizes of nanopores ranging from 30 nm to 10 nm were obtained. Nanopores fabricated on the pyramid-shaped HfO2 film also showed an obvious ion current rectification characteristic, which might improve the nanopore performance as a biomolecule sequencing platform.

  18. Utilization of fermentation waste (Corynebacterium glutamicum) for biosorption of Reactive Black 5 from aqueous solution

    International Nuclear Information System (INIS)

    Vijayaraghavan, K.; Yun, Yeoung-Sang

    2007-01-01

    A fermentation waste, Corynebacterium glutamicum, was successfully employed as a biosorbent for Reactive Black 5 (RB5) from aqueous solution. This paper initially studied the effect of pretreatment on the biosorption capacity of C. glutamicum toward RB5, using several chemical agents, such as HCl, H 2 SO 4 , HNO 3 , NaOH, Na 2 CO 3 , CaCl 2 and NaCl. Among these reagents, 0.1 M HNO 3 gave the maximum enhancement of the RB5 uptake, exhibiting 195 mg/g at pH 1 with an initial RB5 concentration of 500 mg/l. The solution pH and temperature were found to affect the biosorption capacity, and the biosorption isotherms derived at different pHs and temperatures revealed that a low pH (pH 1) and high temperature (35 deg. C) favored biosorption. The biosorption isotherm was well represented using three-parameter models (Redlich-Peterson and Sips) compared to two-parameter models (Langmuir and Freundlich models). As a result, high correlation coefficients and low average percentage error values were observed for three-parameter models. A maximum RB5 uptake of 419 mg/g was obtained at pH 1 and a temperature of 35 deg. C, according to the Langmuir model. The kinetics of the biosorption process with different initial concentrations (500-2000 mg/l) was also monitored, and the data were analyzed using pseudo-first and pseudo-second order models, with the latter describing the data well. Various thermodynamic parameters, such as ΔG o , ΔH o and ΔS o , were calculated, indicating that the present system was a spontaneous and endothermic process. The use of a 0.1 M NaOH solution successfully desorbed almost all the dye molecules from dye-loaded C. glutamicum biomass at different solid-to-liquid ratios examined

  19. Effect of chloride ions on the corrosion behavior of low-alloy steel containing copper and antimony in sulfuric acid solution

    Science.gov (United States)

    Park, Sun-Ah; Kim, Seon-Hong; Yoo, Yun-Ha; Kim, Jung-Gu

    2015-05-01

    The influence of the addition of HCl on the corrosion behavior of low-alloy steel containing copper and antimony was investigated using electrochemical (potentiodynamic and potentiostatic polarization tests, and electrochemical impedance spectroscopy) and weight loss tests in a 1.6M H2SO4 solution with different concentrations of hydrochloric acid (0.00, 0.08, 0.15 and 0.20 M HCl) at 60 °C. The result showed that the corrosion rate decreased with increasing HCl by the formation of protective layers. SEM, EDS and XPS examinations of the corroded surfaces after the immersion test indicated that the corrosion production layer formed in the solution containing HCl was highly comprised of metallic Cu, Cu chloride and metallic (Fe, Cu, Sb) compounds. The corrosion resistance was improved by the Cu-enriched layer, in which chloride ions are an accelerator for cupric ion reduction during copper deposition. Furthermore, cuprous and antimonious chloride species are complex salts for cuprous ions adsorbed on the surface during copper deposition.

  20. Nanotube formation and morphology change of Ti alloys containing Hf for dental materials use

    International Nuclear Information System (INIS)

    Jeong, Yong-Hoon; Lee, Kang; Choe, Han-Cheol; Ko, Yeong-Mu; Brantley, William A.

    2009-01-01

    In this paper, Ti-Hf (10, 20, 30 and 40 wt.%) alloys were prepared by arc melting, and subjected to heat treatment for 24 h at 1000 o C in an argon atmosphere. Formation of surface nanotubes was achieved by anodizing a Ti-Hf alloy in 1.0 M H 3 PO 4 electrolytes with small amounts of NaF at room temperature. Microstructures of the alloys and nanotube morphology were examined by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The homogenized Ti-Hf alloys had a needle-like microstructure of α phase, and nanotubes formed on Ti-xHf alloys had the anatase phase after treatment that promoted crystallization. Uniform nanotubes formed for Hf contents up to 20 wt.%. Irregular nanotubes formed on the Ti-30Hf and Ti-40Hf alloys. The structure of the irregular layers on the Ti-30Hf and Ti-40Hf alloys had nanotubes of two sizes. Increasing the Hf content in Ti led to the formation of nanotubes with more narrow size. The pores in the nanotubes typically had a diameter ranging from 80-120 nm and a length of approximately 1.7 μm. It is concluded that nanotube morphology on Ti-Hf alloys can controlled by varying the amount of Hf.

  1. 40 CFR 180.1273 - Beauveria bassiana HF23; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Beauveria bassiana HF23; exemption... FOOD Exemptions From Tolerances § 180.1273 Beauveria bassiana HF23; exemption from the requirement of a tolerance. Residues of Beauveria bassiana HF23 are exempt from the requirement of a tolerance on all food...

  2. Photon strength function in the Hf-181 nucleus by method of two-step cascade

    International Nuclear Information System (INIS)

    Le Hong Khiem

    2003-01-01

    The applicability of sum-coincidence measurements of two-step cascade gamma ray spectra determining Photon Strength Function (PSF) of Hf-181 induced from Hf-180 (n,2γ) Hf-181 reaction is presented. Up to 80% intensity of the primary gamma ray transitions in a wide energy range have been deduced and compared to model calculation. (author)

  3. Action mechanism of hydrogen gas on deposition of HfC coating using HfCl{sub 4}-CH{sub 4}-H{sub 2}-Ar system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yalei, E-mail: yaleipm@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 (China); School of Metallurgy and Environment, Central South University, Changsha, 410083 (China); Li, Zehao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 (China); Xiong, Xiang, E-mail: xiongx@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 (China); Li, Xiaobin [School of Metallurgy and Environment, Central South University, Changsha, 410083 (China); Chen, Zhaoke; Sun, Wei [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 (China)

    2016-12-30

    Highlights: • HfC coatings were deposited on C/C composites by LPCVD using HfCl4-CH4-H2-Ar system. • Action mechanism of H2 on structure and growth behavior of HfC coating was studied. • Increased H2 concentration leads to transformation in growth mechanism of coating. - Abstract: Hafnium carbide coatings were deposited on carbon/carbon composites by low pressure chemical vapor deposition using HfCl{sub 4}-CH{sub 4}-H{sub 2}-Ar system. The microstructure, mechanical and ablation resistance performance of HfC coatings deposited with various H{sub 2} concentrations were investigated. The effect of hydrogen gas on the deposition of HfC coating was also discussed. Results show that all of the deposited coatings are composed of single cubic HfC phase, the hydrogen gas acted as a crucial role in determining the preferred orientation, microstructure and growth behavior of HfC coatings. During the deposition process, the gas phase supersaturation of the reaction species can be controlled by adjusting the hydrogen gas concentration. When deposited with low hydrogen gas concentration, the coating growth was dominated by the nucleation of HfC, which results in the particle-stacked structure of HfC coating. Otherwise, the coating growth was dominated by the crystal growth at high hydrogen gas concentration, which leads to the column-arranged structure of HfC coating. Under the ablation environment, the coating C2 exhibits better configurational stability and ablation resistance. The coating structure has a significant influence on the mechanical and ablation resistance properties of HfC coating.

  4. The anisotropy of Hf diffusion in α-Zr

    International Nuclear Information System (INIS)

    Hood, G.M.; Zou, H.; Roy, J.A.; Schultz, R.J.; Matsuura, N.; Jackson, J.A.

    1995-07-01

    Hf diffusion coefficients (D) have been measured in the temperature interval 870-1100 K, in directions parallel (D pa ) and perpendicular (D pe ) to the c-axis of double-faced, single crystal specimens of both high-purity (HP) and nominally pure (NP) α-Zr single crystals. The diffusion profiles were measured by secondary ion mass spectrometry. Hf diffusion in HP α-Zr is characterised by an activation energy of about 3.0 eV and a pre-exponential factor of about 10 -5 m 2 /s. The anisotropy ratio, D pa /D pe is ∼ 1.0 for the NP specimens. A dependence of D on diffusion time/depth is indicated for some NP experiments on NP Zr. (author). 7 refs., 2 tabs., 3 figs

  5. First demonstration of HF-driven ionospheric currents

    Science.gov (United States)

    Papadopoulos, K.; Chang, C.-L.; Labenski, J.; Wallace, T.

    2011-10-01

    The first experimental demonstration of HF driven currents in the ionosphere at low ELF/ULF frequencies without relying in the presence of electrojets is presented. The effect was predicted by theoretical/computational means in a recent letter and given the name Ionospheric Current Drive (ICD). The effect relies on modulated F-region HF heating to generate Magneto-Sonic (MS) waves that drive Hall currents when they reach the E-region. The Hall currents inject ELF waves into the Earth-Ionosphere waveguide and helicon and Shear Alfven (SA) waves in the magnetosphere. The proof-of-concept experiments were conducted using the HAARP heater in Alaska under the BRIOCHE program. Waves between 0.1-70 Hz were measured at both near and far sites. The letter discusses the differences between ICD generated waves and those relying on modulation of electrojets.

  6. Picture analysis in CT-HF and its CT photographs

    International Nuclear Information System (INIS)

    Kubota, Kazuo; Kohirasawa, Hideo; Shinojima, Masayasu; Tokui, Mitsuru; Seo, Kunihiko.

    1980-01-01

    CT (computed tomography) apparatus is rarely used yet in the field of dentistry, though it seems useful. It is possibly because of the artefacts caused by the metallic parts attached to teeth, the large partial volume effect due to many bones and the problems of positioning and reproducibility. After considering the various requirements of the CT apparatuses in dental field, CT-HF (of T/R type) was chosen as such apparatus, and installed as the first in dentistry. In the CT-HF apparatus, the inner diameter of the gantry is up to 300 mm, and the position of a tomographic plane is only 40 mm away from the front of gantry. Mainly the usefulness of scanography in positioning and the usefulness of the CT apparatus in the picture analysis and processing in dental field are described. (J.P.N.)

  7. Fe substitution and pressure effects on superconductor Re6Hf

    Science.gov (United States)

    Yang, Jinhu; Guo, Yang; Wang, Hangdong; Chen, Bin

    2018-04-01

    Polycrystalline samples of (Re1-xFex) 6Hf were synthesized by arc-melting method and the phase purity of the samples was confirmed by powder X-ray diffraction method. In this paper, we report the Fe substitution and pressure effect on non-centrosymmetric superconductor Re6Hf. The superconducting transition temperature, TC, is confirmed by the measurements of magnetic susceptibility, electrical resistivity for x ≤ 0.22 samples with the temperature down to 2 K. We find that the TC is suppressed with the increase of Fe content. The upper critical field Hc2 is larger than the value predicted by the WHH theory and shows a linear temperature dependence down to 2 K. When upon the application of external pressure up to 2.5 GPa, the TC decreases monotonically at a rate dlnTC/dP of 0.01 GPa-1.

  8. Comparison between HF radar current data and moored ADCP currentmeter

    International Nuclear Information System (INIS)

    Cosoli, S.

    2005-01-01

    A preliminary assessment of accuracy of a two-sites shore-based HF Radar network along the Venice Lagoon littoral was attempted by means of comparison with a 57.5 day-long ADCP current time series for the period September-October 2002. Results showed that radar measurements were accurate ( O . The main differences between the HF radar and surface ADCP currents can be explained in terms of random errors affecting the measurement technique and the daily sea breeze forcing, since low-pass filtering of current time series significantly improved the correlation and decreased the RMS of the differences between the two measured data set. Comparison of the semidiurnal (M2, S2) tidal band suggested good agreement between tidal ellipse amplitudes. Wind forcing on a daily time-scale (sea-breeze) was associated with larger differences between radar and ADCP currents at a diurnal band due to the presence of a vertical shear in the surface layer

  9. Closed cycle high-repetition-rate pulsed HF laser

    Science.gov (United States)

    Harris, Michael R.; Morris, A. V.; Gorton, Eric K.

    1997-04-01

    The design and performance of a closed cycle high repetition rate HF laser is described. A short pulse, glow discharge is formed in a 10 SF6:1 H2 gas mixture at a total pressure of approximately 110 torr within a 15 by 0.5 by 0.5 cm3 volume. Transverse, recirculated gas flow adequate to enable repetitive operation up to 3 kHz is imposed by a centrifugal fan. The fan also forces the gas through a scrubber cell to eliminate ground state HF from the gas stream. An automated gas make-up system replenishes spent gas removed by the scrubber. Typical mean laser output powers up to 3 W can be maintained for extended periods of operation.

  10. Performance Analysis of HF Band FB-MC-SS

    Energy Technology Data Exchange (ETDEWEB)

    Hussein Moradi; Stephen Andrew Laraway; Behrouz Farhang-Boroujeny

    2016-01-01

    Abstract—In a recent paper [1] the filter bank multicarrier spread spectrum (FB-MC-SS) waveform was proposed for wideband spread spectrum HF communications. A significant benefit of this waveform is robustness against narrow and partial band interference. Simulation results in [1] demonstrated good performance in a wideband HF channel over a wide range of conditions. In this paper we present a theoretical analysis of the bit error probably for this system. Our analysis tailors the results from [2] where BER performance was analyzed for maximum ration combining systems that accounted for correlation between subcarriers and channel estimation error. Equations are give for BER that closely match the simulated performance in most situations.

  11. Beating HF waves to generate VLF waves in the ionosphere

    Science.gov (United States)

    Kuo, Spencer; Snyder, Arnold; Kossey, Paul; Chang, Chia-Lie; Labenski, John

    2012-03-01

    Beat-wave generation of very low frequency (VLF) waves by two HF heaters in the ionosphere is formulated theoretically and demonstrated experimentally. The heater-induced differential thermal pressure force and ponderomotive force, which dominate separately in the D and F regions of the ionosphere, drive an electron current for the VLF emission. A comparison, applying appropriate ionospheric parameters shows that the ponderomotive force dominates in beat-wave generation of VLF waves. Three experiments, one in the nighttime in the absence of D and E layers and two in the daytime in the presence of D and E layers, were performed. X mode HF heaters of slightly different frequencies were transmitted at CW full power. VLF waves at 10 frequencies ranging from 3.5 to 21.5 kHz were generated. The frequency dependencies of the daytime and nighttime radiation intensities are quite similar, but the nighttime radiation is much stronger than the daytime one at the same radiation frequency. The intensity ratio is as large as 9 dB at 11.5 kHz. An experiment directly comparing VLF waves generated by the beat-wave approach and by the amplitude modulation (AM) approach was also conducted. The results rule out the likely contribution of the AM mechanism acting on the electrojet and indicate that beat-wave in the VLF range prefers to be generated in the F region of the ionosphere through the ponderomotive nonlinearity, consistent with the theory. In the nighttime experiment, the ionosphere was underdense to the HF heaters, suggesting a likely setting for effective beat-wave generation of VLF waves by the HF heaters.

  12. Modelling of Phase Equlibria in the Hf-V System\

    Czech Academy of Sciences Publication Activity Database

    Vřešťál, Jan; Pavlů, Jana; Wdowik, U. D.; Šob, Mojmír

    2017-01-01

    Roč. 53, č. 3 (2017), s. 239-247 ISSN 1450-5339 R&D Projects: GA ČR GA14-15576S; GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : Laves phases * Hf-V system * Ab initio calculations * Phase diagram * Zero Kelvin * CALPHAD method Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.804, year: 2016

  13. Ionizing wave via high-power HF acceleration

    OpenAIRE

    Mishin, Evgeny; Pedersen, Todd

    2010-01-01

    Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60 km. This paper presents a physical model of an ionizing wavefront created by suprathermal electrons accelerated by the HF-excited plasma turbulence.

  14. The preparation of HfC/C ceramics via molecular design.

    Science.gov (United States)

    Inzenhofer, Kathrin; Schmalz, Thomas; Wrackmeyer, Bernd; Motz, Günter

    2011-05-07

    Polymer derived ceramics have received lots of attention throughout the last few decades. Unfortunately, only a few precursor systems have been developed, focusing on silicon based polymers and ceramics, respectively. Herein, the synthesis of novel hafnium containing organometallic polymers by two different approaches is reported. Dialkenyl substituted hafnocene monomers were synthesized and subsequently polymerized via a free radical mechanism. Salt metathesis reactions of hafnocene dichloride with bifunctional linkers led to the formation of polymeric materials. NMR spectroscopic methods--in solution as well as in the solid state--were used to characterize the organometallic polymers. Ceramics were finally obtained after cross-linking and thermal treatment under argon (T(max) = 1800 °C). SEM investigations, elemental analyses, Raman spectroscopy and XRD investigations identified the pyrolyzed products as partially crystalline HfC/C mixed phases.

  15. NGRI LAM-MC-ICPMS National Facility: reproducibility of Sr, Nd and Hf isotopic measurements

    International Nuclear Information System (INIS)

    Bhaskar Rao, Y.J.; Vijaya Gopal, B.; Babu, E.V.S.S.K.; Sukumaran, N.P.; Sreenivas, B.; Vijaya Kumar, T.; Krishna, K.V.S.S.; Tomson, J.K.

    2009-01-01

    A laboratory facility was established at the NGRI, primarily to support research in Isotope Geochemistry and Geochronology. Central to this facility are a Multiple Collector-Inductively Coupled Plasma Mass Spectrometer (MC-ICPMS: Nu Plasma HR, Nu Instruments, UK) and a 213 nm Nd-YAG UV Laser Ablation Microprobe (LAM: UP-213, New Wave Research, USA) and a clean chemistry laboratory for dissolution and chromatographic extraction of a range of elements. This article presents a summary of the accuracy and precision of MC-ICPMS Sr, Nd and Hf isotopic measurements (solution mode) on Standard Reference Materials: SRM-987, JNd i and JMC-475 respectively, measured between October 2007 and August 2009

  16. Clinical trials update from the Heart Failure Society of America Meeting 2009: FAST, IMPROVE-HF, COACH galectin-3 substudy, HF-ACTION nuclear substudy, DAD-HF, and MARVEL-1.

    Science.gov (United States)

    Lainscak, Mitja; Coletta, Alison P; Sherwi, Nasser; Cleland, John G F

    2010-02-01

    This article presents findings and a commentary on late-breaking trials presented during the meeting of the Heart Failure Society of America in September 2009. Unpublished reports should be considered as preliminary, since analyses may change in the final publication. The FAST trial showed somewhat better performance of intrathoracic impedance for prediction of deterioration in patients with heart failure (HF) when compared with daily weighing. The IMPROVE-HF study reported the benefits of education on the management of patients with systolic HF. Galectin-3 appeared a useful method for improving risk stratification of patients with chronic HF in a substudy of the COACH trial. A nuclear substudy of the HF-ACTION trial failed to demonstrate that resting myocardial perfusion imaging, a measure of myocardial scar and viability, was clinically useful. A small randomized controlled trial (DAD-HF) suggested that the use of low-dose dopamine in patients with acutely decompensated HF was associated with less deterioration in renal function and less hypokalaemia. The MARVEL-1 trial raises further concerns about the safety of myoblast transplantation in ischaemic HF.

  17. Collision-Induced Dissociation Study of Strong Hydrogen-Bonded Cluster Ions Y-(HF) n (Y=F, O2) Using Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry Combined with a HF Generator.

    Science.gov (United States)

    Sakamoto, Kenya; Sekimoto, Kanako; Takayama, Mitsuo

    2017-01-01

    Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF) n . The HF molecules were ionized in the form of complex ions associated with the negative core ions Y - produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y - (HF) n (Y=F, O 2 ), where larger clusters with n ≥4 were not detected. The mechanisms for the formation of the HF, F - (HF) n , and O 2 - (HF) n species were discussed from the standpoints of the HF generator and APCDI MS. By performing energy-resolved collision-induced dissociation (CID) experiments on the cluster ions F - (HF) n ( n =1-3), the energies for the loss of HF from F - (HF) 3 , F - (HF) 2 , and F - (HF) were evaluated to be 1 eV or lower, 1 eV or higher, and 2 eV, respectively, on the basis of their center-of-mass energy ( E CM ). These E CM values were consistent with the values of 0.995, 1.308, and 2.048 eV, respectively, obtained by ab initio calculations. The stability of [O 2 (HF) n ] - ( n =1-4) was discussed on the basis of the bond lengths of O 2 H-F - (HF) n and O 2 - H-F(HF) n obtained by ab initio calculations. The calculations indicated that [O 2 (HF) 4 ] - separated into O 2 H and F - (HF) 3 .

  18. TID measurement using oblique transmissions of HF pulses

    Science.gov (United States)

    Galkin, Ivan; Reinisch, Bodo; Huang, Xueqin; Paznukhov, Vadym; Hamel, Ryan; Kozlov, Alexander; Belehaki, Anna

    2017-04-01

    The Traveling Ionospheric Disturbance (TID), a wave-like signature of moving plasma density modulation in the ionosphere, is widely acknowledged for its utility in backtracking the anomalous events responsible for the TID generation, and as a major inconvenience to high-frequency (HF) operational systems because of its deleterious impact on the accuracy of navigation and geolocation. The pilot project "Net-TIDE" for the real-time detection and evaluation of TIDs began its operation in 2016 based on the remote-sensing data from synchronized, network-coordinated HF sounding between pairs of DPS4D ionosondes at five participating observatories in Europe. Measurement of all signal properties (Doppler frequency, angle of arrival, and time-of-flight from transmitter to receiver) proved to be instrumental in detecting the TID and deducing the TID parameters: amplitude, wavelength, phase velocity, and direction of propagation. Processing of the measured HF signal data required a specialized signal processing technique that is capable of consistently extracting different signals that have propagated along different ionospheric paths. The multi-path signal environment proved to be the greatest challenge for the reliable TID specification by Net-TIDE, demanding the development of an intelligent system for "signal tracking". The intelligent system is based on a neural network model of a pre-attentive vision capable of extracting continuous signal tracks from the multi-path signal ensemble. Specific examples of the Net-TIDE algorithm suite operation and its suitability for a fully automated TID warning service are discussed.

  19. Modeling of NiTiHf using finite difference method

    Science.gov (United States)

    Farjam, Nazanin; Mehrabi, Reza; Karaca, Haluk; Mirzaeifar, Reza; Elahinia, Mohammad

    2018-03-01

    NiTiHf is a high temperature and high strength shape memory alloy with transformation temperatures above 100oC. A constitutive model based on Gibbs free energy is developed to predict the behavior of this material. Two different irrecoverable strains including transformation induced plastic strain (TRIP) and viscoplastic strain (VP) are considered when using high temperature shape memory alloys (HTSMAs). The first one happens during transformation at high levels of stress and the second one is related to the creep which is rate-dependent. The developed model is implemented for NiTiHf under uniaxial loading. Finite difference method is utilized to solve the proposed equations. The material parameters in the equations are calibrated from experimental data. Simulation results are captured to investigate the superelastic behavior of NiTiHf. The extracted results are compared with experimental tests of isobaric heating and cooling at different levels of stress and also superelastic tests at different levels of temperature. More results are generated to investigate the capability of the proposed model in the prediction of the irrecoverable strain after full transformation in HTSMAs.

  20. Corrosion of high Ni-Cr alloys and Type 304L stainless steel in HNO3-HF

    International Nuclear Information System (INIS)

    Ondrejcin, R.S.; McLaughlin, B.D.

    1980-04-01

    Nineteen alloys were evaluated as possible materials of construction for steam heating coils, the dissolver vessel, and the off-gas system of proposed facilities to process thorium and uranium fuels. Commercially available alloys were found that are satisfactory for all applications. With thorium fuel, which requires HNO 3 -HF for dissolution, the best alloy for service at 130 0 C when complexing agents for fluoride are used is Inconel 690; with no complexing agents at 130 0 C, Inconel 671 is best. At 95 0 C, six other alloys tested would be adequate: Haynes 25, Ferralium, Inconel 625, Type 304L stainless steel, Incoloy 825, and Haynes 20 (in order of decreasing preference); based on composition, six untested alloys would also be adequate. The ions most effective in reducing fluoride corrosion were the complexing agents Zr 4+ and Th 4+ ; Al 3+ was less effective. With uranium fuel, modestly priced Type 304L stainless steel is adequate. Corrosion will be most severe in HNO 3 -HF used occasionally for flushing and in solutions of HNO 3 and corrosion products (ferric and dichromate ions). HF corrosion can be minimized by complexing the fluoride ion and by passivation of the steel with strong nitric acid. Corrosion caused by corrosion products can be minimized by operating at lower temperatures

  1. Robust tribo-mechanical and hot corrosion resistance of ultra-refractory Ta-Hf-C ternary alloy films.

    Science.gov (United States)

    Yate, Luis; Coy, L Emerson; Aperador, Willian

    2017-06-08

    In this work we report the hot corrosion properties of binary and ternary films of the Ta-Hf-C system in V 2 O 5 -Na 2 SO 4 (50%wt.-50%wt.) molten salts at 700 °C deposited on AISI D3 steel substrates. Additionally, the mechanical and nanowear properties of the films were studied. The results show that the ternary alloys consist of solid solutions of the TaC and HfC binary carbides. The ternary alloy films have higher hardness and elastic recoveries, reaching 26.2 GPa and 87%, respectively, and lower nanowear when compared to the binary films. The corrosion rates of the ternary alloys have a superior behavior compared to the binary films, with corrosion rates as low as 0.058 μm/year. The combination and tunability of high hardness, elastic recovery, low nanowear and an excellent resistance to high temperature corrosion demonstrates the potential of the ternary Ta-Hf-C alloy films for applications in extreme conditions.

  2. Isoelectronic substitutions and aluminium alloying in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor

    Science.gov (United States)

    von Rohr, Fabian O.; Cava, Robert J.

    2018-03-01

    High-entropy alloys (HEAs) are a new class of materials constructed from multiple principal elements statistically arranged on simple crystallographic lattices. Due to the large amount of disorder present, they are excellent model systems for investigating the properties of materials intermediate between crystalline and amorphous states. Here we report the effects of systematic isoelectronic replacements, using Mo-Y, Mo-Sc, and Cr-Sc mixtures, for the valence electron count 4 and 5 elements in the body-centered cubic (BCC) Ta-Nb-Zr-Hf-Ti high-entropy alloy (HEA) superconductor. We find that the superconducting transition temperature Tc strongly depends on the elemental makeup of the alloy, and not exclusively its electron count. The replacement of niobium or tantalum by an isoelectronic mixture lowers the transition temperature by more than 60%, while the isoelectronic replacement of hafnium, zirconium, or titanium has a limited impact on Tc. We further explore the alloying of aluminium into the nearly optimal electron count [TaNb] 0.67(ZrHfTi) 0.33 HEA superconductor. The electron count dependence of the superconducting Tc for (HEA)Al x is found to be more crystallinelike than for the [TaNb] 1 -x(ZrHfTi) x HEA solid solution. For an aluminum content of x =0.4 the high-entropy stabilization of the simple BCC lattice breaks down. This material crystallizes in the tetragonal β -uranium structure type and superconductivity is not observed above 1.8 K.

  3. Stabilization effect of a strong HF electrical field on beam-plasma interaction in a relativistic plasma waveguide

    International Nuclear Information System (INIS)

    El-Shorbagy, K.H.

    2000-07-01

    The influence effect of a strong HF electrical field on the excitation of surface waves by an electron beam under the development of instability of low-density electron beam passing through plane relativistic plasma is investigated. Starting from the two fluid plasma model we separate the problem into two parts. The 'temporal' (dynamical) part enables us to find the frequencies and growth rates of unstable waves. This part within the redefinition of natural (eigen) frequencies coincide with the system describing HF suppression of the Buneman instability in a uniform unbounded plasma. Natural frequencies of oscillations and spatial distribution of the amplitude of the self-consistent electrical field are obtained by solving a boundary value problem ('spatial' part) considering a specific spatial distribution of plasma density. Plasma electrons are considered to have a relativistic velocity. It is shown that a HF electric field has no essential influence on dispersion characteristics of unstable surface waves excited in a relativistic plasma waveguide by a low-density electron beam. The region of instability only slightly narrowing and the growth rate decreases by a small parameter and this result has been reduced compared to nonrelativistic plasma. Also, it is found that the plasma electrons have not affected the solution of the space part of the problem. (author)

  4. Investigation of new type Cu-Hf-Al bulk glassy alloys

    International Nuclear Information System (INIS)

    Nagy, E; Ronto, V; Solyom, J; Roosz, A

    2009-01-01

    In the last years new type Cu-Hf-Al ternary alloys were developed with high glass forming ability and ductility. The addition of Al to Cu-Hf alloys results in improvements in glass formation, thermal stability and mechanical properties of these alloys. We have investigated new Cu-based bulk amorphous alloys in Cu-Hf-Al ternary system. The alloys with Cu 49 Hf 42 Al 9 , Cu 46 Hf 45 Al 9 , Cu 50 Hf 42.5 Al 7.5 and Cu 50 Hf 45 Al 5 compositions were prepared by arc melting. The samples were made by centrifugal casting and were investigated by X-ray diffraction method. Thermodynamic properties were examined by differential scanning calorimetry and the structure of the crystallising phases by scanning electron microscopy. The determination of liquidus temperatures of alloys were measured by differential thermal analysis.

  5. Separation and recovery of lead from a low concentration solution of lead(II) and zinc(II) using the hydrolysis production of poly styrene-co-maleic anhydride.

    Science.gov (United States)

    Liang, Xing; Su, Yibing; Yang, Ying; Qin, Wenwu

    2012-02-15

    The PbZn separation/preconcentration technique, based on the complex formation reaction of Pb(II) and Zn(II), using a copolymer poly(styrene-co-maleic anhydride) (PSMA), without adding any carrier element was developed. The effects of several experimental parameters such as solution pH, temperature and adsorption time were studied. The experimental results show that the PSMA resin-Pb equilibrium was achieved in 2 min and the Pb(II) loading capacity is up to 641.62 mg g(-1) in aqueous solution under optimum conditions, which is much higher than the Zn(II) loading capacity within 80 min. The adsorption test for Pb(II) indicates that PSMA can recover Pb(II) from a mixed solution of Pb(II), Zn(II) and light metals such as Ca(II) and Mg(II) with higher adsorption rate and larger selective coefficient. A further study indicates that PSMA as chelating resins recovering Pb(II) can be regenerated via mineral acid (6M H(2)SO(4)). PSMA was synthesized by radical polymerization and tested as an adsorbent for the selective recovery of Pb(II). In addition, the formation procedure and structure of Pb-PSMA complex were also studied. Both the PSMA and the Pb-PSMA complex were characterized by means of FTIR spectroscopy, elemental analysis, gel permeation chromatography (GPC) and atomic absorption spectrometry (AAS). Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Nightside studies of coherent HF Radar spectral width behaviour

    Directory of Open Access Journals (Sweden)

    E. E. Woodfield

    2002-09-01

    Full Text Available A previous case study found a relationship between high spectral width measured by the CUTLASS Finland HF radar and elevated electron temperatures observed by the EISCAT and ESR incoherent scatter radars in the post-midnight sector of magnetic local time. This paper expands that work by briefly re-examining that interval and looking in depth at two further case studies. In all three cases a region of high HF spectral width (>200 ms-1 exists poleward of a region of low HF spectral width (<200 ms-1. Each case, however, occurs under quite different geomagnetic conditions. The original case study occurred during an interval with no observed electrojet activity, the second study during a transition from quiet to active conditions with a clear band of ion frictional heating indicating the location of the flow reversal boundary, and the third during an isolated sub-storm. These case studies indicate that the relationship between elevated electron temperature and high HF radar spectral width appears on closed field lines after 03:00 magnetic local time (MLT on the nightside. It is not clear whether the same relationship would hold on open field lines, since our analysis of this relationship is restricted in latitude. We find two important properties of high spectral width data on the nightside. Firstly the high spectral width values occur on both open and closed field lines, and secondly that the power spectra which exhibit high widths are both single-peak and multiple-peak. In general the regions of high spectral width (>200 ms-1 have more multiple-peak spectra than the regions of low spectral widths whilst still maintaining a majority of single-peak spectra. We also find that the region of ion frictional heating is collocated with many multiple-peak HF spectra. Several mechanisms for the generation of high spectral width have been proposed which would produce multiple-peak spectra, these are discussed in relation to the data presented here. Since the

  7. Nightside studies of coherent HF Radar spectral width behaviour

    Directory of Open Access Journals (Sweden)

    E. E. Woodfield

    Full Text Available A previous case study found a relationship between high spectral width measured by the CUTLASS Finland HF radar and elevated electron temperatures observed by the EISCAT and ESR incoherent scatter radars in the post-midnight sector of magnetic local time. This paper expands that work by briefly re-examining that interval and looking in depth at two further case studies. In all three cases a region of high HF spectral width (>200 ms-1 exists poleward of a region of low HF spectral width (<200 ms-1. Each case, however, occurs under quite different geomagnetic conditions. The original case study occurred during an interval with no observed electrojet activity, the second study during a transition from quiet to active conditions with a clear band of ion frictional heating indicating the location of the flow reversal boundary, and the third during an isolated sub-storm. These case studies indicate that the relationship between elevated electron temperature and high HF radar spectral width appears on closed field lines after 03:00 magnetic local time (MLT on the nightside. It is not clear whether the same relationship would hold on open field lines, since our analysis of this relationship is restricted in latitude. We find two important properties of high spectral width data on the nightside. Firstly the high spectral width values occur on both open and closed field lines, and secondly that the power spectra which exhibit high widths are both single-peak and multiple-peak. In general the regions of high spectral width (>200 ms-1 have more multiple-peak spectra than the regions of low spectral widths whilst still maintaining a majority of single-peak spectra. We also find that the region of ion frictional heating is collocated with many multiple-peak HF spectra. Several mechanisms for the generation of high spectral width have been proposed which would produce multiple-peak spectra, these are discussed in relation to

  8. Chemical studies on the distribution of some heavy metals between two immiscible solutions

    International Nuclear Information System (INIS)

    Rizk, S.E.M.

    2011-01-01

    Separation and recovery of divalent zinc and cobalt ions from mixed sulphate and thiocyanate solutions have been carried out using CYANEX 921 (trioctylphosphine oxide), CYANEX 923 (a mixture of straight chain alkylated phosphine oxides) and CYANEX 925 (a mixture of branched chain alkylated phosphine oxides) in kerosene. Different parameters affecting the extraction equilibrium of Zn(II) and Co(II) in addition to temperature, were studied and the stoichiometry of the extracted Zn(II) and Co(II) species were postulated based on slope analysis method. The respective loaded organic phases were stripped with different mineral acids. The extraction percent of metal ions was found to increase with increasing ph and zinc was preferentially extracted over cobalt in the different investigated systems. The highest separation factor was obtained when using 0.015 M CYANEX 925 as extractant. Based on the obtained results, application of the method was tested to separate Zn(II) and Co(II) from Nickel Metal Hydride batteries (Ni-MH batteries) leached by 2.0 M H 2 SO 4 and good results were obtained. The extraction of Zn(II) and Co(II) from aqueous mixed sulphate and thiocyanate medium through supported liquid membrane (SLM) using CYANEX 925 in kerosene as carrier supported on cellulose nitrate membrane was studied. The influence of different parameters on the permeation of the investigated metals such as ph, extractant concentration, sulphuric acid concentration, thiocyanate concentration and strip solution concentration were also studied. The selectivity of the used system for Zn / Co separation is evaluated.

  9. Temperature dependence of the resistivity and tunneling magnetoresistance of sputtered FeHf(Si)O cermet films

    NARCIS (Netherlands)

    Strijkers, G.J.; Swagten, H.J.M.; Rulkens, B.; Bitter, R.H.J.N.; Jonge, de W.J.M.; Bloemen, P.J.H.; Schep, K.M.

    1998-01-01

    We have studied the tunneling resistivity and magnetoresistance of reactive sputter deposited FeHfO and FeHfSiO thin granular films. Maximum magnetoresistance ratios at room temperature of 2% and 3.2% were observed for films with compositions of Fe47Hf10O43 and Fe40Hf6Si6O48, respectively. The

  10. Characteristics of transfer of europium ions from phosphoric acid solution into the CaSO4·O.5H2O solid phase

    International Nuclear Information System (INIS)

    Berdonosova, D.G.; Burlakova, E.V.; Yasenkova, M.A.; Ivanov, L.N.; Melikhov, I.V.

    1989-01-01

    The mechanism of formation of the precipitated CaSO 4 ·0.5H 2 O phase was studied in detail; the precipitation was performed at 80 degree, equimolar solutions of Ca(H 2 PO 4 ) 2 and H 2 SO 4 in phosphoric acid of 38% concentration being used. The availability of detailed information on the mechanism of formation of CaSO 4 ·0.5H 2 O precipitates determined the choice of conditions of study of capture of rare earths. In particular, H 3 PO 4 of 38% P 2 O 5 concentration was used as the medium of formation of the calcium sulfate precipitate. Europium was chosen as the rare earth. Its behavior in the liquid and solid phases was studied by radiometric and luminescence methods. The radionuclide 152 Eu is convenient as a radioactive tracer while luminescence of europium is structure-sensitive; therefore, europium is often used in physicochemical investigations as a luminescent probe. It follows from the data that most of the europium captured by the precipitate during coagulation of the ultramicrocrystals is retained firmly by the solid phase. Therefore, in order to diminish capture of europium (and other rare earths) by the precipitate coagulation of the latter should be prevented

  11. Study of the solubility of yttrium, praseodymium, neodymium, and gadolinium sulfates in the presence of sodium and potassium in sulfuric-phosphoric acid solutions at 20 deg C

    International Nuclear Information System (INIS)

    Lokshin, Eh.P.; Tareeva, O.A.; Kashulina, T.G.

    2007-01-01

    The solubility of yttrium, praseodymium, neodymium, and gadolinium sulfates in the presence of sodium and potassium ions and the composition of solid phases were studied at 20 deg C in relation to the concentration of acids in sulfuric acid, phosphoric acid, and sulfuric-phosphoric acid solutions containing up to 36 wt % H 2 SO 4 and 33.12 g 1 -1 H 3 PO 4 . The formation of double sulfates of praseodymium and neodymium with sodium and potassium ions, as well as of gadolinium sulfate with sodium ions of the composition 1 : 1 was revealed. In water at 20 deg C, the solubility products of PrNa(SO 4 ) 2 ·H 2 O, NdNa(SO 4 ) 2 ·H 2 O, GdNa(SO 4 ) 2 ·H 2 O, PrK(SO 4 ) 2 ·H 2 O, and NdK(SO 4 ) 2 ·H 2 O are found to be 7.28x10 -8 , 7.84x10 -8 , 3.09x10 -6 , 3.02x10 -6 , and 1.70x10 -6 , respectively [ru

  12. Pyridine sorption from aqueous solution by rice husk ash (RHA) and granular activated carbon (GAC): Parametric, kinetic, equilibrium and thermodynamic aspects

    International Nuclear Information System (INIS)

    Lataye, D.H.; Mishra, I.M.; Mall, I.D.

    2008-01-01

    The present study deals with the adsorption of pyridine (Py) from synthetic aqueous solutions by rice husk ash (RHA) and commercial grade granular activated carbon (GAC) and reports on the kinetic, equilibrium and thermodynamic aspects of Py sorption. Batch sorption studies were carried out to evaluate the effect of various parameters, such as adsorbent dose (m), initial pH (pH 0 ), contact time (t), initial concentration (C 0 ) and temperature (T) on the removal of Py. The maximum removal of Py is found to be ∼96% and ∼97% at lower concentrations ( -3 ) and ∼79.5% and ∼84% at higher concentrations (600 mg dm -3 ) using 50 kg m -3 and 30 kg m -3 of RHA and GAC dosage, respectively, at 30 ± 1 o C. Adsorption of Py is found to be endothermic in nature and the equilibrium data can be adequately represented by Toth and Redlich-Peterson isotherm equations. Py can be recovered from the spent adsorbents by using acidic water and 0.1 N H 2 SO 4 . The overall adsorption of Py on RHA and GAC is found to be in the order of GAC > RHA. Comparative assessment of adsorbents used by various investigators available in literature showed the effectiveness of BFA and RHA over other adsorbents. Spent RHA can simply be filtered, dried and used in the boiler furnaces/incinerators. Thus, its heating value can be recovered

  13. Investigation on the Effect of Green Inhibitors for Corrosion Protection of Mild Steel in 1 M NaOH Solution

    Directory of Open Access Journals (Sweden)

    Premjith Jayakumar Ramakrishnan

    2014-01-01

    Full Text Available Alkaline corrosion is one of the main issues faced by the industries. The main chemicals abundantly used in industries are NaOH, H3PO4, HCl, and H2SO4. Corrosion control of metals has technical, economical, environmental, and aesthetical importance. The use of inhibitors is one of the best options to protect metals and alloys against corrosion. The corrosion protection of mild steel in 1 M NaOH solution by mix of Henna/Zeolite powder was studied at different temperatures by weight loss technique. Adsorption, activation, and statistical studies were addressed in this work. Adsorption studies showed that inhibitor adsorbed on metal surface according to Langmuir isotherm. Surface studies were performed by using UV-spectra and SEM. The adsorption of inhibitor on the steel surface was found to obey Langmuir’s adsorption isotherm. The inhibition efficiency increased with increasing concentration of the inhibitor in NaOH medium. Inhibition mechanism is deduced from the concentration and temperature dependence of the inhibition efficiency, Langmuir’s adsorption isotherm, SEM, and UV spectroscopic results.

  14. Solidification Rate Dependence of Microstructures and Transformation Behavior of Ti-Ni-Hf Alloys.

    Science.gov (United States)

    Kim, Dong-Jo; Kim, Yeon-Wook; Nam, Tae-Hyun

    2018-09-01

    The microstructures and transformation behavior of Ti-49Ni-20Hf, Ti-49.5Ni-20Hf and Ti-50.3Ni- 20Hf alloys, when prepared by conventional casting, were investigated and compared with the properties of the alloys prepared by melt spinning. The area fraction of (Ti,Hf)2Ni in Ti-Ni-Hf alloys decreased to 3.9% from 9.4% as Ni content rose to 50.3 at% from 49 at%. Several cracks were observed in the hot-rolled Ti-49Ni-20Hf alloy sheet but none were found in the Ti-50.3Ni-20Hf alloy sheet. The B2-B19' transformation start temperature (Ms) decreased to 476 K from 580 K as Ni content increased to 50.3 at% from 49 at%. All the as-spun ribbons were amorphous, and the activation energy for crystallization ranged from 167.8 kJ/mol to 182.7 kJ/mol based on Ni content. When annealing temperature ranged from 810 K to 873 K, crystalline Ti-Ni-Hf alloys without (Ti,Hf)2Ni particles were obtained. At annealing temperatures higher than 873 K, very fine (Ti,Hf)2Ni particles, less than 20 nm in size, were found embedded in a crystalline matrix.

  15. Effects of HfB2 and HfN Additions on the Microstructures and Mechanical Properties of TiB2-Based Ceramic Tool Materials

    Science.gov (United States)

    An, Jing; Song, Jinpeng; Liang, Guoxing; Gao, Jiaojiao; Xie, Juncai; Cao, Lei; Wang, Shiying; Lv, Ming

    2017-01-01

    The effects of HfB2 and HfN additions on the microstructures and mechanical properties of TiB2-based ceramic tool materials were investigated. The results showed that the HfB2 additive not only can inhibit the TiB2 grain growth but can also change the morphology of some TiB2 grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine microstructure, and that the HfN additive had a tendency toward agglomeration. The improvement of flexural strength and Vickers hardness of the TiB2-HfB2 ceramics was due to the relatively fine microstructure; the decrease of fracture toughness was ascribed to the formation of a weaker grain boundary strength due to the brittle rim phase and the poor wettability between HfB2 and Ni. The decrease of the flexural strength and Vickers hardness of the TiB2-HfN ceramics was due to the increase of defects such as TiB2 coarse grains and HfN agglomeration; the enhancement of fracture toughness was mainly attributed to the decrease of the pore number and the increase of the rim phase and TiB2 coarse grains. The toughening mechanisms of TiB2-HfB2 ceramics mainly included crack bridging and transgranular fracture, while the toughening mechanisms of TiB2-HfN ceramics mainly included crack deflection, crack bridging, transgranular fracture, and the core-rim structure. PMID:28772821

  16. Effects of HfB2 and HfN Additions on the Microstructures and Mechanical Properties of TiB2-Based Ceramic Tool Materials

    Directory of Open Access Journals (Sweden)

    Jing An

    2017-04-01

    Full Text Available The effects of HfB2 and HfN additions on the microstructures and mechanical properties of TiB2-based ceramic tool materials were investigated. The results showed that the HfB2 additive not only can inhibit the TiB2 grain growth but can also change the morphology of some TiB2 grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine microstructure, and that the HfN additive had a tendency toward agglomeration. The improvement of flexural strength and Vickers hardness of the TiB2-HfB2 ceramics was due to the relatively fine microstructure; the decrease of fracture toughness was ascribed to the formation of a weaker grain boundary strength due to the brittle rim phase and the poor wettability between HfB2 and Ni. The decrease of the flexural strength and Vickers hardness of the TiB2-HfN ceramics was due to the increase of defects such as TiB2 coarse grains and HfN agglomeration; the enhancement of fracture toughness was mainly attributed to the decrease of the pore number and the increase of the rim phase and TiB2 coarse grains. The toughening mechanisms of TiB2-HfB2 ceramics mainly included crack bridging and transgranular fracture, while the toughening mechanisms of TiB2-HfN ceramics mainly included crack deflection, crack bridging, transgranular fracture, and the core-rim structure.

  17. High Q-factor tunable superconducting HF circuit

    CERN Document Server

    Vopilkin, E A; Pavlov, S A; Ponomarev, L I; Ganitsev, A Y; Zhukov, A S; Vladimirov, V V; Letyago, A G; Parshikov, V V

    2001-01-01

    Feasibility of constructing a high Q-factor (Q approx 10 sup 5) mechanically tunable in a wide range of frequencies (12-63 MHz) vibration circuit of HF range was considered. The tunable circuit integrates two single circuits made using YBaCuO films. The circuit frequency is tuned by changing distance X (capacity) between substrates. Potentiality of using substrates of lanthanum aluminate, neodymium gallate and strontium titanate for manufacture of single circuits was considered. Q-factor of the circuit amounted to 68000 at resonance frequency of 6.88 MHz

  18. High Q-factor tunable superconducting HF circuit

    International Nuclear Information System (INIS)

    Vopilkin, E.A.; Parafin, A.E.; Pavlov, S.A.; Ponomarev, L.I.; Ganitsev, A.Yu.; Zhukov, A.S.; Vladimirov, V.V.; Letyago, A.G.; Parshikov, V.V.

    2001-01-01

    Feasibility of constructing a high Q-factor (Q ∼ 10 5 ) mechanically tunable in a wide range of frequencies (12-63 MHz) vibration circuit of HF range was considered. The tunable circuit integrates two single circuits made using YBaCuO films. The circuit frequency is tuned by changing distance X (capacity) between substrates. Potentiality of using substrates of lanthanum aluminate, neodymium gallate and strontium titanate for manufacture of single circuits was considered. Q-factor of the circuit amounted to 68000 at resonance frequency of 6.88 MHz [ru

  19. TEA HF laser with a high specific radiation energy

    Science.gov (United States)

    Puchikin, A. V.; Andreev, M. V.; Losev, V. F.; Panchenko, Yu. N.

    2017-01-01

    Results of experimental studies of the chemical HF laser with a non-chain reaction are presented. The possibility of the total laser efficiency of 5 % is shown when a traditional C-to-C pumping circuit with the charging voltage of 20-24 kV is used. It is experimentally shown that the specific radiation output energy of 21 J/l is reached at the specific pump energy of 350 J/l in SF6/H2 = 14/1 mixture at the total pressure of 0.27 bar.

  20. Ionosphere research with a HF/MF cubesat radio instrument

    Science.gov (United States)

    Kallio, Esa; Aikio, Anita; Alho, Markku; Fontell, Mathias; Harri, Ari-Matti; Kauristie, Kirsti; Kestilä, Antti; Koskimaa, Petri; Mäkelä, Jakke; Mäkelä, Miika; Turunen, Esa; Vanhamäki, Heikki; Verronen, Pekka

    2017-04-01

    New technology provides new possibilities to study geospace and 3D ionosphere by using spacecraft and computer simulations. A type of nanosatellites, CubeSats, provide a cost effective possibility to provide in-situ measurements in the ionosphere. Moreover, combined CubeSat observations with ground-based observations gives a new view on auroras and associated electromagnetic phenomena. Especially joint and active CubeSat - ground based observation campaigns enable the possibility of studying the 3D structure of the ionosphere. Furthermore using several CubeSats to form satellite constellations enables much higher temporal resolution. At the same time, increasing computation capacity has made it possible to perform simulations where properties of the ionosphere, such as propagation of the electromagnetic waves in the medium frequency, MF (0.3-3 MHz) and high frequency, HF (3-30 MHz), ranges is based on a 3D ionospheric model and on first-principles modelling. Electromagnetic waves at those frequencies are strongly affected by ionospheric electrons and, consequently, those frequencies can be used for studying the plasma. On the other hand, even if the ionosphere originally enables long-range telecommunication at MF and HF frequencies, the frequent occurrence of spatiotemporal variations in the ionosphere disturbs communication channels, especially at high latitudes. Therefore, study of the MF and HF waves in the ionosphere has both a strong science and technology interests. We introduce recently developed simulation models as well as measuring principles and techniques to investigate the arctic ionosphere by a polar orbiting CubeSat whose novel AM radio instrument measures HF and MF waves. The cubesat, which contains also a white light aurora camera, is planned to be launched in late 2017 (http://www.suomi100satelliitti.fi/eng). The new models are (1) a 3D ray tracing model and (2) a 3D full kinetic electromagnetic simulation. We also introduce how combining of the

  1. Azeotrope in LiF-HfF4 system

    International Nuclear Information System (INIS)

    Sorokin, I.D.; Korenev, Yu.M.; Sidorov, L.N.

    1975-01-01

    The gaseous phase of the system LiF-HfF 4 is investigated by means of isothermal evaporation. Using experimental data, p-X diagrams are constructed for 1125, 1075, 1025, 975 and 925 K. It is shown that the azeotrope with minimum total pressure observed at 1125 K degenerates upon lowering of the temperature and entry into the heterogeneous region. At 975 K the azeotrope corresponds to the point of inflexion from the horizontal tangent on the total pressure curve. At lower temperatures azeotropic distillation is absent from the system. (author)

  2. Bidirectional communication in an HF hybrid organic/solution-processed metal-oxide RFID tag

    NARCIS (Netherlands)

    Myny, K.; Rockelé, M.; Chasin, A.; Pham, D.V.; Steiger, J.; Botnaras, S.; Weber, D.; Herold, B.; Ficker, J.; Van Putten, B.D.; Gelinck, G.H.; Genoe, J.; Dehaene, W.; Heremans, P.

    2014-01-01

    A bidirectional communication protocol allows radio-frequency identification (RFID) tags to have readout of multiple tags in the RF field without collision of data. In this paper, we realized bidirectional communication between a reader system and thin-film RFID tag by introducing a novel protocol

  3. A routine high-precision method for Lu-Hf isotope geochemistry and chronology

    Science.gov (United States)

    Patchett, P.J.; Tatsumoto, M.

    1981-01-01

    A method for chemical separation of Lu and Hf from rock, meteorite and mineral samples is described, together with a much improved mass spectrometric running technique for Hf. This allows (i) geo- and cosmochronology using the176Lu???176Hf+??- decay scheme, and (ii) geochemical studies of planetary processes in the earth and moon. Chemical yields for the three-stage ion-exchange column procedure average 90% for Hf. Chemical blanks are international mass spectrometric standard; suitable aliquots, prepared from a single batch of JMC 475, are available from Denver. Lu-Hf analyses of the standard rocks BCR-1 and JB-1 are given. The potential of the Lu-Hf method in isotope geochemistry is assessed. ?? 1980 Springer-Verlag.

  4. Determination of total and extractable hydrogen peroxide in organic and aqueous solutions of uranyl nitrate

    International Nuclear Information System (INIS)

    Goodall, Ph.

    1999-01-01

    The development of a spectrophotometric method for the determination of hydrogen peroxide in uranyl nitrate solutions is reported. The method involves the measurement of the absorbance at 520 mm of a vanadyl peroxide species. This species was formed by the addition of a reagent consisting of vanadium (V) (50 mmol x dm -3 ) in dilute sulphuric acid (2 mol x dm -3 H 2 SO 4 ). This reagent, after dilution, was also used as an extractant for organic phase samples. The method is simple and robust and tolerant of nitric acid and U(VI). Specificity and accuracy were improved by the application of solid phase extraction techniques to remove entrained organic solvents and Pu(VI). Reverse phase solid phase extraction was used to clean-up aqueous samples or extracts which were contaminated with entrained solvent. A solid phase extraction system based upon an extraction chromatography system was used to remove Pu(IV). Detection limits of 26 μmol x dm -3 (0.88 μg x cm -3 ) or 7 μmol x dm -3 (0.24 μg x cm -3 ) for, respectively, a 1 and 4 cm path length cell were obtained. Precisions of RSD = 1.4% and 19.5% were obtained at the extremes of the calibration curve (5 mmol x dm -3 and 50 μmol x dm -3 H 2 O 2 , 1 cm cell). The introduction of the extraction and clean-up stages had a negligible effect upon the precision of the determination. The stability of an organic phase sample was tested and no loss of analyte could be discerned over a period of at least 5 days. (author)

  5. Enhanced resistive switching and multilevel behavior in bilayered HfAlO/HfAlO{sub x} structures for non-volatile memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Faita, F. L., E-mail: fabriciofaita@gmail.com [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Departamento de Física, Universidade Federal de Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC (Brazil); Silva, J. P. B., E-mail: josesilva@fisica.uminho.pt [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto (Portugal); Pereira, M.; Gomes, M. J. M. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2015-12-14

    In this work, hafnium aluminum oxide (HfAlO) thin films were deposited by ion beam sputtering deposition technique on Si substrate. The presence of oxygen vacancies in the HfAlO{sub x} layer deposited in oxygen deficient environment is evidenced from the photoluminescence spectra. Furthermore, HfAlO(oxygen rich)/HfAlO{sub x}(oxygen poor) bilayer structures exhibit multilevel resistive switching (RS), and the switching ratio becomes more prominent with increasing the HfAlO layer thickness. The bilayer structure with HfAlO/HfAlO{sub x} thickness of 30/40 nm displays the enhanced multilevel resistive switching characteristics, where the high resistance state/intermediate resistance state (IRS) and IRS/low resistance state resistance ratios are ≈10{sup 2} and ≈5 × 10{sup 5}, respectively. The switching mechanisms in the bilayer structures were investigated by the temperature dependence of the three resistance states. This study revealed that the multilevel RS is attributed to the coupling of ionic conduction and the metallic conduction, being the first associated to the formation and rupture of conductive filaments related to oxygen vacancies and the second with the formation of a metallic filament. Moreover, the bilayer structures exhibit good endurance and stability in time.

  6. Development of Cu-Hf-Al ternary systems and tungsten wire/particle reinforced Cu48Hf43Al9 bulk metallic glass composites for strengthening

    International Nuclear Information System (INIS)

    Park, Joyoung; An, Jihye; Choi-Yim, Haein

    2010-01-01

    Stable bulk glass forming alloys can be developed over a wide range of compositions in Cu-Hf-Al ternary systems starting from the Cu 49 Hf 42 Al 9 bulk metallic glass. Ternary Cu-Hf-Al alloys can be cast directly from the melt into copper molds to form fully amorphous strips with thicknesses of 1 to 6 mm. The maximum critical diameter of the new Cu-Hf-Al ternary alloy was 6 mm. X-ray diffraction patterns were used to confirm the amorphous nature of the ternary Cu-Hf-Al alloys. To increase the toughness of these metallic glasses, we reinforced the Cu 48 Hf 43 Al 9 bulk metallic glass-forming liquid with a 50% volume fraction of tungsten particles and an 80% volume fraction of tungsten wires with diameters of 242.4 μm. Composites with a critical diameter of 7 mm and length 70 mm were synthesized. The structure of the composites was confirmed by using X-ray diffraction (XRD), and the scanning electron microscopy (SEM). The mechanical properties of the composites were studied in compression tests. The thermal stability and the crystallization processes of the Cu-Hf-Al alloys and composites were investigated by using differential scanning calorimetry (DSC). Values of the glass transition temperature (T g ), the crystallization temperature (T x ), and the supercooled liquid region (ΔT = T x - T g ) are given in this paper.

  7. Fretting wear of ZrN and Zr(21% Hf)N coatings

    Energy Technology Data Exchange (ETDEWEB)

    Atar, E. [Gebze Inst. of Tech., Material Science and Engineering Dept., Kocaeli (Turkey); Cimenoglu, H.; Kayali, E.S. [Istanbul Technical Univ., Dept. of Metallurgy and Materials Engineering, Istanbul (Turkey)

    2004-07-01

    In this study, the wear behaviours of ZrN and Zr(21% Hf)N coatings, deposited on hardened AISI D2 cold work tool steel were examined by a fretting wear tester. The hardness of ZrN and Zr(21% Hf)N coatings were almost the same, where as they exhibited different wear resistance. Addition of 21% Hf to ZrN coating achieved about 25% increase in the wear resistance. (orig.)

  8. Fretting wear of ZrN and Zr(21% Hf)N coatings

    International Nuclear Information System (INIS)

    Atar, E.; Cimenoglu, H.; Kayali, E.S.

    2004-01-01

    In this study, the wear behaviours of ZrN and Zr(21% Hf)N coatings, deposited on hardened AISI D2 cold work tool steel were examined by a fretting wear tester. The hardness of ZrN and Zr(21% Hf)N coatings were almost the same, where as they exhibited different wear resistance. Addition of 21% Hf to ZrN coating achieved about 25% increase in the wear resistance. (orig.)

  9. Simultaneous measurements of HF-enhanced plasma waves and artificial field-aligned irregularities at Arecibo

    International Nuclear Information System (INIS)

    Noble, S.T.; Djuth, F.T.

    1990-01-01

    Two radar systems with beams intersecting in the HF-modified F region were used to simultaneously measure HF-enhanced plasma lines (HFPLs) and artificial geomagnetic field-aligned irregularities (AFAIs). The Arecibo 430-MHz radar was used for the HFPL observations, and a portable 49.92-MHz backscatter radar was deployed on the island of Guadeloupe to monitor the AFAIs. The experiment was desgined to examine the degree to which HF-induced plasma turbulence influences the development of AFAIs. When the HF beam is stepped up in power, sustained HFPLs and AFAIs are first observed at the same HF power level, indicating that ponderomotively driven instabilities may be involved in the early time development of AFAIs. As the HF power is increased, the HFPL backscatter power begins to saturate at ∼70 MW effective radiated power (ERP). However, the backscatter from AFAIs is linearly dependent on HF power, even at the highest (120 MW ERP) HF power levels available at Arecibo. This suggests that additional processes may contribute to the development of AFAIs. For example, ponderomotively driven instabilities may give rise to weak geomagnetic field-aligned irregularities that are subsequently driven unstable by processes excited near the upper hybrid resonance. It is also likely that AFAIs greatly impact the development of HF-induced plasma turbulence at late times (>1 s) following HF turn-on. Once the ionosphere is preconditioned by high-power HF modifications, AFAIs and HFPLs can be simultaneously sustained at a much lower HF power level than that needed to originally excite them. The nature of the preconditioning process is currently not well understood. New theoretical initiatives are clearly needed to guide future experimental activity in this area

  10. Assembly of the CMS HF (hadron forward) calorimeter, April 2003 to June 2005

    CERN Multimedia

    Tejinder S. Virdee, CERN

    2005-01-01

    The forward calorimeters (HF) of the CMS hadron calorimeter system are located 11.2 m from the interaction point. Each HF module is composed by 18 wedges, made of steel absorbers and radiation-hard quartz fibers. The photogallery shows the wedges (Figs. 1-3, April 2003), the assembly of one HF module (Figs. 4-9, May and June 2004) and the assembly of the other (Figs. 10-11, June 2005)

  11. Nuclear quadrupole interactions in ferroelectric compounds of HF/sup 181/

    Energy Technology Data Exchange (ETDEWEB)

    Kunzler, J V

    1971-01-01

    Measurements of nuclear quadrupole interaction constants in perovkite-type compounds of PbHfO/sub 3/, SnhfO/sub 3/, CaHfO/sub 3/ e SrHfO/sub 3/ have been performed using the perturbed angular correlation technique. A range of fundamental frequencies from 150 to 550 Megaradians per second was determined. The variation of quadrupole constants has been discussed through the molecular orbital theory.

  12. Small signal gain measurements in a small scale HF overtone laser

    Energy Technology Data Exchange (ETDEWEB)

    Wisniewski, C.F.; Hewett, K.B.; Manke, G.C. II; Hager, G.D. [Air Force Research Laboratory, Directed Energy Directorate, 3550 Aberdeen Ave SE, Kirtland AFB, NM 87117-5776 (United States); Crowell, P.G. [Northrup Grumman Information Technology, Science and Technology Operating Unit, Advanced Technology Division, P.O. Box 9377, Albuquerque, NM 87119-9377 (United States); Truman, C.R. [Mechanical Engineering Department, University of New Mexico, Albuquerque, NM 87131 (United States)

    2003-07-01

    The overtone gain medium of a small-scale HF overtone laser was probed using a sub-Doppler tunable diode laser. Two-dimensional spatially resolved small signal gain and temperature maps were generated for several ro-vibrational transitions in the HF (v=2{yields}v=0) overtone band. Our results compare well with previous measurements of the overtone gain in a similar HF laser device. (orig.)

  13. Phase1 upgrade of the CMS-HF Calorimeter

    CERN Document Server

    Gulmez, Erhan

    2016-01-01

    In this presentation, results of the Phase I upgrade of the CMS Hadron Forward Calorimeter (HF) are discussed. The CMS-HF Calorimeter was using regular PMTs. Cherenkov light produced in the quartz fibers embedded in the iron absorber was read out with the PMTs. However, occasionally, stray muons hitting the PMT windows cause Cherenkov radiation in the PMT itself and produce large signals. These large signals mimic a very high-energy particle and are tagged as important by the trigger. To reduce this problem, PMTs had to be replaced. The four-anode PMTs that were chosen have thinner windows; thereby reducing the Cherenkov radiation in the PMT window. As part of the upgrade, the read-out electronics is to be replaced so that the PMTs are read out in two channels by connecting each pair of anodes to a single channel. Information provided by these two channels will help us reject the false signals due to the stray muons since the Cherenkov radiation in the PMT window is more likely to produce a signal only in one...

  14. Reversible spin texture in ferroelectric Hf O2

    Science.gov (United States)

    Tao, L. L.; Paudel, Tula R.; Kovalev, Alexey A.; Tsymbal, Evgeny Y.

    2017-06-01

    Spin-orbit coupling effects occurring in noncentrosymmetric materials are known to be responsible for nontrivial spin configurations and a number of emergent physical phenomena. Ferroelectric materials may be especially interesting in this regard due to reversible spontaneous polarization making possible a nonvolatile electrical control of the spin degrees of freedom. Here, we explore a technologically relevant oxide material, Hf O2 , which has been shown to exhibit robust ferroelectricity in a noncentrosymmetric orthorhombic phase. Using theoretical modelling based on density-functional theory, we investigate the spin-dependent electronic structure of the ferroelectric Hf O2 and demonstrate the appearance of chiral spin textures driven by spin-orbit coupling. We analyze these spin configurations in terms of the Rashba and Dresselhaus effects within the k .p Hamiltonian model and find that the Rashba-type spin texture dominates around the valence-band maximum, while the Dresselhaus-type spin texture prevails around the conduction band minimum. The latter is characterized by a very large Dresselhaus constant λD= 0.578 eV Å, which allows using this material as a tunnel barrier to produce tunneling anomalous and spin Hall effects that are reversible by ferroelectric polarization.

  15. HF Radio Angle-of-Arrival Measurements and Ionosonde Positioning

    Directory of Open Access Journals (Sweden)

    Lung-Chih Tsai

    2014-01-01

    Full Text Available Since 2010 a 2nd generation NOAA MF/HF radar, also referred to as the VIPIR ionosonde, has been operated at Hualien, Taiwan (23.8973°N, 121.5503°E. The Hualien VIPIR ionosonde is a modern ionospheric radar, fully digitizing complex signal records and using multiple parallel receiver channels for simultaneous signal measurements from multiple spaced receiving antennas. This paper considers radio direction finding based on interferometric phase measurements from a horizontal antenna array in the Hualien VIPIR ionosonde system. We applied the Hermite normal form method to solve the phase-measurement aliasing and least squares problems and improve the radio angle-of-arrival (AOA measurements. Backward ray-tracing simulation has been proposed to determine radio transmitter position. This paper presents a numerical, step by step ray-tracing method based on the IGRF superimposed onto a phenomenological ionospheric electron density model, the TaiWan Ionospheric Model (TWIM. The proposed methodology is successfully applied to locate two experimental HF radio transmitters at Longquan and Chungli with distance errors within 5 km and less than 5% of the great circle distances.

  16. HF Radar Sea-echo from Shallow Water

    Directory of Open Access Journals (Sweden)

    Josh Kohut

    2008-08-01

    Full Text Available HF radar systems are widely and routinely used for the measurement of ocean surface currents and waves. Analysis methods presently in use are based on the assumption of infinite water depth, and may therefore be inadequate close to shore where the radar echo is strongest. In this paper, we treat the situation when the radar echo is returned from ocean waves that interact with the ocean floor. Simulations are described which demonstrate the effect of shallow water on radar sea-echo. These are used to investigate limits on the existing theory and to define water depths at which shallow-water effects become significant. The second-order spectral energy increases relative to the first-order as the water depth decreases, resulting in spectral saturation when the waveheight exceeds a limit defined by the radar transmit frequency. This effect is particularly marked for lower radar transmit frequencies. The saturation limit on waveheight is less for shallow water. Shallow water affects second-order spectra (which gives wave information far more than first-order (which gives information on current velocities, the latter being significantly affected only for the lowest radar transmit frequencies for extremely shallow water. We describe analysis of radar echo from shallow water measured by a Rutgers University HF radar system to give ocean wave spectral estimates. Radar-derived wave height, period and direction are compared with simultaneous shallow-water in-situ measurements.

  17. Thermoluminescence in films of HfO2:Dy+3

    International Nuclear Information System (INIS)

    Ceron, P.; Rivera, T.; Guzman, J.; Montes, E.; Pelaez, A.; Rojas, B.; Guzman, D.; Azorin, J.; Paredes, L.

    2014-08-01

    In this work the thermoluminescence (TL) response of films of hafnium oxide polluted with dysprosium (HfO 2 :Dy +3 ) that were irradiated in the near UV (200 nm - 400 nm). The films were deposited by means of the ultrasonics spray pyrolysis technique on a glass substrate, using different deposit temperatures (300 grades C - 600 grades C). The best TL emission corresponded to the prepared film to 450 grades C that was exposed to a spectral irradiation of 80 μJ/(cm 2 -s) with a wave longitude of 240 nm. The TL response in function of the spectral irradiation was lineal in the studied interval (24 to 288 mJ/cm 2 ), several kinetic parameters were also calculated of the shine curve as depth of the trap (E), frequency factor (s) and order to the kinetics (b). The obtained results show that the films of HfO 2 :Dy +3 could be used as radiation monitor in the region of the near UV. (Author)

  18. Pressure-induced phase transformation of HfO2

    International Nuclear Information System (INIS)

    Arashi, H.

    1992-01-01

    This paper reports on the pressure dependence of the Raman spectra of HfO 2 that was measured by a micro-Raman technique using a single-crystal specimen in the pressure range from 0 to 10 GPa at room temperature. The symmetry assignment of Raman bands of the monoclinic phase was experimentally accomplished from the polarization measurements for the single crystal. With increased pressure, a phase transformation for the monoclinic phase took place at 4.3 ± 0.3 GPa. Nineteen Raman bands were observed for the high-pressure phase. The spectral structure of the Raman bands for the high-pressure phase was similar with those reported previously for ZrO 2 . The space group for the high pressure phase of HfO 2 was determined as Pbcm, which was the same as that of the high-pressure phase for ZrO 2 on the basis of the number and the spectral structure of the Raman bands

  19. Synthesis, characterization, kinetic and thermodynamic studies of the dissolution of ThO2 and of solid solutions Th1-xMxO2 (M = U, Pu)

    International Nuclear Information System (INIS)

    Heisbourg, G.

    2003-12-01

    The aim of this work was to understand the mechanisms of dissolution of ThO 2 and of thorium mixed oxides such as Th 1-x U x O 2 and Th 1-x Pu x O 2 in aqueous, oxygenated or inert media. Several solids have been synthesized by precipitation in oxalic medium: Th 1-x U x O 2 (x= 0.11; 0.24; 0.37; 0.53; 0.67; 0.81 and 0.91) and Th 1-x Pu x O 2 (x= 0.13; 0.32 and 0.66). They have been characterized by XRD, SEM, TEM, XPS, XAS, PIXE and EPMA. The sintering conditions of these materials have been studied and optimized in order to obtain sintered samples with a measured density very near the theoretical densities. A kinetic study of the dissolution of ThO 2 and of solid solutions Th 1-x U x O 2 has been carried out in several aqueous media (HNO 3 , HCl, H 2 SO 4 ) in terms of several parameters: protons concentration, temperature, pH, ionic strength, nature of the electrolyte solution and uranium molar ratio for the solid solutions Th 1-x U x O 2 in order to determine the kinetic laws of dissolution of the solid solutions having different compositions comparatively to ThO 2 . The leaching tests carried out in natural waters of compositions near those of the deep geologic sites considered for the storage of nuclear wastes have shown that the dissolution of the solids was bound to the complexing effect of the constitutional ions of the water considered. The leaching tests carried out on sintered samples of the same composition have led to the same normalized dissolution velocities. The thermodynamic aspect of the dissolution of the solid solutions Th 1-x U x O 2 in nitric medium has been studied at last. (O.M.)

  20. Study of Direct-Contact HfO2/Si Interfaces

    Directory of Open Access Journals (Sweden)

    Noriyuki Miyata

    2012-03-01

    Full Text Available Controlling monolayer Si oxide at the HfO2/Si interface is a challenging issue in scaling the equivalent oxide thickness of HfO2/Si gate stack structures. A concept that the author proposes to control the Si oxide interface by using ultra-high vacuum electron-beam HfO2 deposition is described in this review paper, which enables the so-called direct-contact HfO2/Si structures to be prepared. The electrical characteristics of the HfO2/Si metal-oxide-semiconductor capacitors are reviewed, which suggest a sufficiently low interface state density for the operation of metal-oxide-semiconductor field-effect-transistors (MOSFETs but reveal the formation of an unexpected strong interface dipole. Kelvin probe measurements of the HfO2/Si structures provide obvious evidence for the formation of dipoles at the HfO2/Si interfaces. The author proposes that one-monolayer Si-O bonds at the HfO2/Si interface naturally lead to a large potential difference, mainly due to the large dielectric constant of the HfO2. Dipole scattering is demonstrated to not be a major concern in the channel mobility of MOSFETs.

  1. Chemical stability and defect formation in CaHfO3

    KAUST Repository

    Alay-E-Abbas, Syed Muhammad

    2014-04-01

    Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

  2. Chemical stability and defect formation in CaHfO3

    KAUST Repository

    Alay-E-Abbas, Syed Muhammad; Nazir, Safdar; Mun Wong, Kin; Shaukat, Ali; Schwingenschlö gl, Udo

    2014-01-01

    Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

  3. Microhardness variation and related microstructure in Al-Cu alloys prepared by HF induction melting and RF sputtering

    Science.gov (United States)

    Boukhris, N.; Lallouche, S.; Debili, M. Y.; Draissia, M.

    2009-03-01

    The materials under consideration are binary aluminium-copper alloys (10 at% to 90.3 at%Cu) produced by HF melting and RF magnetron sputtering. The resulting micro structures have been observed by standard metallographic techniques, X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Vickers microhardness of bulk Al-Cu alloys reaches a maximum of 1800 MPa at 70.16 at%Cu. An unexpected metastable θ ' phase has been observed within aluminium grain in Al-37 at%Cu. The mechanical properties of a family of homogeneous Al{1-x}Cu{x} (0 Al-Cu targets have been investigated. The as-deposited microstructures for all film compositions consisted of a mixture of the two expected face-centred-cubic (fcc) Al solid solution and tetragonal θ (Al{2}Cu) phases. The microhardness regularly increases and the grain size decreases both with copper concentration. This phenomenon of significant mechanical strengthening of aluminium by means of copper is essentially due to a combination between solid solution effects and grain size refinement. This paper reports some structural features of different Al-Cu alloys prepared by HF melting and RF magnetron on glass substrate sputtering.

  4. Evolution of E 2 transition strength in deformed hafnium isotopes from new measurements on 172Hf,174Hf, and 176Hf

    Science.gov (United States)

    Rudigier, M.; Nomura, K.; Dannhoff, M.; Gerst, R.-B.; Jolie, J.; Saed-Samii, N.; Stegemann, S.; Régis, J.-M.; Robledo, L. M.; Rodríguez-Guzmán, R.; Blazhev, A.; Fransen, Ch.; Warr, N.; Zell, K. O.

    2015-04-01

    Background: The available data for E 2 transition strengths in the region between neutron-deficient hafnium and platinum isotopes are far from complete. More and precise data are needed to enhance the picture of structure evolution in this region and to test state-of-the-art nuclear models. In a simple model, the maximum collectivity is expected at the middle of the major shell. However, for actual nuclei, particularly in heavy-mass regions, which should be highly complex, this picture may no longer be the case, and one should use a more realistic nuclear-structure model. We address this point by studying the spectroscopy of Hf as a representative case. Purpose: We remeasure the 21+ half-lives of 172,174,176Hf, for which there is some disagreement in the literature. The main goal is to measure, for the first time, the half-lives of higher-lying states of the rotational band. The new results are compared to a theoretical calculation for absolute transition strengths. Method: The half-lives were measured using γ -γ and conversion-electron-γ delayed coincidences with the fast timing method. For the determination of half-lives in the picosecond region, the generalized centroid difference method was applied. For the theoretical calculation of the spectroscopic properties, the interacting boson model is employed, whose Hamiltonian is determined based on microscopic energy-density functional calculations. Results: The measured 21+ half-lives disagree with results from earlier γ -γ fast timing measurements, but are in agreement with data from Coulomb excitation experiments and other methods. Half-lives of the 41+ and 61+ states were measured, as well as a lower limit for the 81+ states. Conclusions: This work shows the importance of a mass-dependent effective boson charge in the interacting boson model for the description of E 2 transition rates in chains of nuclei. It encourages further studies of the microscopic origin of this mass dependence. New experimental

  5. Separations chemistry

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    Infrared spectra of Pu(IV) polymer show effects of CO 2 adsorption and of aging. Uv light (300 nm) increases the rate of reduction of PuO 2 2+ and Pu 4+ to Pu 3+ and the Pu--U separation factor using TBP. Distribution ratios for Zr and Hf between Dowex 50W--X8 resin and H 2 SO 4 solutions were found to decrease sharply with H 2 SO 4 content. Octylphenyl acid phosphate, a mixture of monooctylphenyl and dioctylphenyl phosphoric acids, is being studied for U recovery from wet-process phosphoric acid. A study of HNO 3 leaching of Ra from U ores was completed. Effects of particle size of the packed bed on the dispersion of the boundary of the miscible phase used in oil recovery are being studied. Effects of sulfonates on toluene--n-butanol--water phase relations were determined, as were the effects of salts and solutes on the max water content of 1:1 toluene--alcohol solutions. A study was begun of hydrocarbon solubility in water--surfactant--alcohol. The mechanism of the formation of hydrous ZrO 2 --polyacrylate membranes and their use for sulfate rejection were studied. Salt rejection through hyperfiltration by clay membranes (bentonite and kaolin) was also investigated. Preliminary results are given for hyperfiltration of wood-pulping wastes by ZrO 2 membranes. 13 figures

  6. Flotation separation of hafnium(IV) from aqueous solutions

    International Nuclear Information System (INIS)

    Downey, D.M.; Narick, C.N.; Cohen, T.A.

    1985-01-01

    A simple, rapid method for the separation of hafnium from aqueous solutions was investigated using sup(175+181)Hf tracer. Cationic hafnium complex ions were floated from dilute acid solutions with sodium lauryl sulfate (SLS) and anionic hafnium complexes were floated from basic and oxalic acid solutions with hexadecyltrimethyl ammonium bromide (HTMAB). The conditions necessary for quantitative recovery of the metal and mechanisms of flotation are described. (author)

  7. Flotation separation of hafnium(IV) from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Downey, D.M.; Narick, C.N.; Cohen, T.A.

    1985-09-01

    A simple, rapid method for the separation of hafnium from aqueous solutions was investigated using sup(175 + 181)Hf tracer. Cationic hafnium complex ions were floated from dilute acid solutions with sodium lauryl sulfate (SLS) and anionic hafnium complexes were floated from basic and oxalic acid solutions with hexadecyltrimethyl ammonium bromide (HTMAB). The conditions necessary for quantitative recovery of the metal and mechanisms of flotation are described. (author). 21 refs.; 5 figs.

  8. A new potential energy surface for vibration-vibration coupling in HF-HF collisions. Formulation and quantal scattering calculations

    Science.gov (United States)

    Schwenke, David W.; Truhlar, Donald G.

    1988-04-01

    We present new ab initio calculations of the HF-HF interaction potential for the case where both molecules are simultaneously displaced from their equilibrium internuclear distance. These and previous ab initio calculations are then fit to a new analytic representation which is designed to be efficient to evaluate and to provide an especially faithful account of the forces along the vibrational coordinates. We use the new potential for two sets of quantal scattering calculations for collisions in three dimensions with total angular momentum zero. First we test that the angular harmonic representation of the anisotropy is adequate by comparing quantal rigid rotator calculations to those carried out for potentials involving higher angular harmonics and for which the expansion in angular harmonics is systematically increased to convergence. Then we carry out large-scale quantal calculations of vibration-vibration energy transfer including the coupling of both sets of vibrational and rotational coordinates. These calculations indicate that significant rotational energy transfer accompanies the vibration-to-vibration energy transfer process.

  9. Doppler shift simulation of scattered HF signals during the Tromsø HF pumping experiment on 16 February 1996

    Directory of Open Access Journals (Sweden)

    T. D. Borisova

    2002-09-01

    Full Text Available Comparisons between bistatic scatter measurements and simulation results during the Tromsø HF pumping experiment on 16 February 1996 are made. Doppler measurements of an HF diagnostic signal scattered from the field-aligned irregularities (FAIs in the auroral E-region were carried out on the London – Tromsø – St. Petersburg path at 9410 kHz from 21:00 to 22:00 UT. The scattered signals were observed both from natural and artificial ionospheric irregularities located in the vicinity of Tromsø. To simulate the Doppler frequency shifts, fd , of scattered signals, a radio channel model, named CONE, was developed. The model allows for ray tracing, group and phase paths, and Doppler frequency shift calculations. The calculated Doppler shifts were analyzed for dependence on the magnitude and direction of plasma velocities in the scattering volume. It was found that the velocity components in the north-south direction are crucial for explaining the Doppler frequency shifts of the scattered diagnostic signals. To simulate fd , real velocities obtained from the EISCAT UHF radar at an altitude of 278 km and from the digital all-sky imager during the experiment were employed. The simulation results of Doppler frequency shift variations with time are in reasonable agreement with the experimental Doppler shifts of scattered signals on the London – Tromsø – St. Petersburg path.Key words. Ionosphere (active experiments; ionospheric irregularities Radio science (ionospheric propagation

  10. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

    Beitz, J.V.; Williams, C.W.

    1996-01-01

    Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 ± 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO 4 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO 2 F 2 . Studies on the effect of added LiNO 3 or Na 2 WO 4 ·2H 2 O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF 6 content of WF 6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF 6

  11. Vacuum-jacketed hydrofluoric acid solution calorimeter

    Science.gov (United States)

    Robie, R.A.

    1965-01-01

    A vacuum-jacketed metal calorimeter for determining heats of solution in aqueous HF was constructed. The reaction vessel was made of copper and was heavily gold plated. The calorimeter has a cooling constant of 0.6 cal-deg -1-min-1, approximately 1/4 that of the air-jacketed calorimeters most commonly used with HF. It reaches equilibrium within 10 min after turning off the heater current. Measurements of the heat of solution of reagent grade KCl(-100 mesh dried 2 h at 200??C) at a mole ratio of 1 KCl to 200 H2O gave ??H = 4198??11 cal at 25??C. ?? 1965 The American Institute of Physics.

  12. Reliability assessment of ultra-thin HfO2 films deposited on silicon wafer

    International Nuclear Information System (INIS)

    Fu, Wei-En; Chang, Chia-Wei; Chang, Yong-Qing; Yao, Chih-Kai; Liao, Jiunn-Der

    2012-01-01

    Highlights: ► Nano-mechanical properties on annealed ultra-thin HfO 2 film are studied. ► By AFM analysis, hardness of the crystallized HfO 2 film significantly increases. ► By nano-indention, the film hardness increases with less contact stiffness. ► Quality assessment on the annealed ultra-thin films can thus be achieved. - Abstract: Ultra-thin hafnium dioxide (HfO 2 ) is used to replace silicon dioxide to meet the required transistor feature size in advanced semiconductor industry. The process integration compatibility and long-term reliability for the transistors depend on the mechanical performance of ultra-thin HfO 2 films. The criteria of reliability including wear resistance, thermal fatigue, and stress-driven failure rely on film adhesion significantly. The adhesion and variations in mechanical properties induced by thermal annealing of the ultra-thin HfO 2 films deposited on silicon wafers (HfO 2 /SiO 2 /Si) are not fully understood. In this work, the mechanical properties of an atomic layer deposited HfO 2 (nominal thickness ≈10 nm) on a silicon wafer were characterized by the diamond-coated tip of an atomic force microscope and compared with those of annealed samples. The results indicate that the annealing process leads to the formation of crystallized HfO 2 phases for the atomic layer deposited HfO 2 . The HfSi x O y complex formed at the interface between HfO 2 and SiO 2 /Si, where the thermal diffusion of Hf, Si, and O atoms occurred. The annealing process increases the surface hardness of crystallized HfO 2 film and therefore the resistance to nano-scratches. In addition, the annealing process significantly decreases the harmonic contact stiffness (or thereafter eliminate the stress at the interface) and increases the nano-hardness, as measured by vertically sensitive nano-indentation. Quality assessments on as-deposited and annealed HfO 2 films can be thereafter used to estimate the mechanical properties and adhesion of ultra-thin HfO 2

  13. Reliability assessment of ultra-thin HfO{sub 2} films deposited on silicon wafer

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Wei-En [Center for Measurement Standards, Industrial Technology Research Institute, Room 216, Building 8, 321 Kuang Fu Road Sec. 2, Hsinchu, Taiwan (China); Chang, Chia-Wei [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Chang, Yong-Qing [Center for Measurement Standards, Industrial Technology Research Institute, Room 216, Building 8, 321 Kuang Fu Road Sec. 2, Hsinchu, Taiwan (China); Yao, Chih-Kai [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Liao, Jiunn-Der, E-mail: jdliao@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Nano-mechanical properties on annealed ultra-thin HfO{sub 2} film are studied. Black-Right-Pointing-Pointer By AFM analysis, hardness of the crystallized HfO{sub 2} film significantly increases. Black-Right-Pointing-Pointer By nano-indention, the film hardness increases with less contact stiffness. Black-Right-Pointing-Pointer Quality assessment on the annealed ultra-thin films can thus be achieved. - Abstract: Ultra-thin hafnium dioxide (HfO{sub 2}) is used to replace silicon dioxide to meet the required transistor feature size in advanced semiconductor industry. The process integration compatibility and long-term reliability for the transistors depend on the mechanical performance of ultra-thin HfO{sub 2} films. The criteria of reliability including wear resistance, thermal fatigue, and stress-driven failure rely on film adhesion significantly. The adhesion and variations in mechanical properties induced by thermal annealing of the ultra-thin HfO{sub 2} films deposited on silicon wafers (HfO{sub 2}/SiO{sub 2}/Si) are not fully understood. In this work, the mechanical properties of an atomic layer deposited HfO{sub 2} (nominal thickness Almost-Equal-To 10 nm) on a silicon wafer were characterized by the diamond-coated tip of an atomic force microscope and compared with those of annealed samples. The results indicate that the annealing process leads to the formation of crystallized HfO{sub 2} phases for the atomic layer deposited HfO{sub 2}. The HfSi{sub x}O{sub y} complex formed at the interface between HfO{sub 2} and SiO{sub 2}/Si, where the thermal diffusion of Hf, Si, and O atoms occurred. The annealing process increases the surface hardness of crystallized HfO{sub 2} film and therefore the resistance to nano-scratches. In addition, the annealing process significantly decreases the harmonic contact stiffness (or thereafter eliminate the stress at the interface) and increases the nano-hardness, as measured by vertically

  14. Do Hf isotopes in magmatic zircons represent those of their host rocks?

    Science.gov (United States)

    Wang, Di; Wang, Xiao-Lei; Cai, Yue; Goldstein, Steven L.; Yang, Tao

    2018-04-01

    Lu-Hf isotopic system in zircon is a powerful and widely used geochemical tracer in studying petrogenesis of magmatic rocks and crustal evolution, assuming that zircon Hf isotopes can represent initial Hf isotopes of their parental whole rock. However, this assumption may not always be valid. Disequilibrium partial melting of continental crust would preferentially melt out non-zircon minerals with high time-integrated Lu/Hf ratios and generate partial melts with Hf isotope compositions that are more radiogenic than those of its magma source. Dissolution experiments (with hotplate, bomb and sintering procedures) of zircon-bearing samples demonstrate this disequilibrium effect where partial dissolution yielded variable and more radiogenic Hf isotope compositions than fully dissolved samples. A case study from the Neoproterozoic Jiuling batholith in southern China shows that about half of the investigated samples show decoupled Hf isotopes between zircons and the bulk rocks. This decoupling could reflect complex and prolonged magmatic processes, such as crustal assimilation, magma mixing, and disequilibrium melting, which are consistent with the wide temperature spectrum from ∼630 °C to ∼900 °C by Ti-in-zircon thermometer. We suggest that magmatic zircons may only record the Hf isotopic composition of their surrounding melt during crystallization and it is uncertain whether their Hf isotopic compositions can represent the primary Hf isotopic compositions of the bulk magmas. In this regard, using zircon Hf isotopic compositions to trace crustal evolution may be biased since most of these could be originally from disequilibrium partial melts.

  15. HfC plasma coating of C/C composites

    International Nuclear Information System (INIS)

    Boncoeur, M.; Schnedecker, G.; Lulewicz, J.D.

    1992-01-01

    The surface properties of C/C composites such as hardness and corrosion or erosion resistance can be modified by a ceramic coating applied by plasma torch. The technique of plasma spraying in controlled temperature and atmosphere, that was developed and patented by the CEA, makes it possible to apply coatings to the majority of metals and ceramics without affecting the characteristics of the composite. An example of hard deposit of HfC on a C/C composite is described. The characteristics of the deposit and of the bonding with the C/C composite were studied before and after a heat treatment under vacuum for 2 hours at 1000 C. 2 refs

  16. Generation and amplification of nanaosecond duration multiline hf laser pulses

    International Nuclear Information System (INIS)

    Getzinger, R.L.; Ware, K.D.; Carpenter, J.P.

    1976-01-01

    High-power, fast-rising pulses of hydrogen fluoride laser energy suitable for laser-fusion target interaction experiments can in principle be generated by directing an electro-optically shuttered oscillator pulse through one or more electron-beam driven amplifiers. A three-stage HF master oscillator-power amplifier (MOPA) configuration was constructed and tested using SF 6 -C 2 H 6 in which an E-O generated 4-ns-FWHM pulse was amplified in an electron-beam-excited third stage and subsequently isolated with a Brewster angle splitter. Independent experiments in which a 100-ns-FWHM pilot pulse interacted with the power amplifier demonstrated for the first time complete extraction of the available laser energy. These two results provide strong evidence that with upgrading to H 2 -F 2 , it should be possible to obtain nanosecond duration pulses with power levels sufficient for meaningful laser fusion target coupling experiments

  17. Ternary ceramic alloys of Zr-Ce-Hf oxides

    Science.gov (United States)

    Becher, P.F.; Funkenbusch, E.F.

    1990-11-20

    A ternary ceramic alloy is described which produces toughening of zirconia and zirconia composites through the stress transformation from tetragonal phase to monoclinic phase. This alloy, having the general formula Ce[sub x]Hf[sub y]Zr[sub 1[minus]x[minus]y]O[sub 2], is produced through the addition of appropriate amounts of ceria and hafnia to the zirconia. Typically, improved toughness is achieved with about 5 to about 15 mol % ceria and up to about 40 mol % hafnia. The preparation of alloys of these compositions are given together with data as to the densities, tetragonal phase content, hardness and fracture toughness. The alloys are useful in preparing zirconia bodies as well as reinforcing ceramic composites. 1 fig.

  18. Updated climatological model predictions of ionospheric and HF propagation parameters

    International Nuclear Information System (INIS)

    Reilly, M.H.; Rhoads, F.J.; Goodman, J.M.; Singh, M.

    1991-01-01

    The prediction performances of several climatological models, including the ionospheric conductivity and electron density model, RADAR C, and Ionospheric Communications Analysis and Predictions Program, are evaluated for different regions and sunspot number inputs. Particular attention is given to the near-real-time (NRT) predictions associated with single-station updates. It is shown that a dramatic improvement can be obtained by using single-station ionospheric data to update the driving parameters for an ionospheric model for NRT predictions of f(0)F2 and other ionospheric and HF circuit parameters. For middle latitudes, the improvement extends out thousands of kilometers from the update point to points of comparable corrected geomagnetic latitude. 10 refs

  19. Silicon/HfO2 interface: Effects of proton irradiation

    International Nuclear Information System (INIS)

    Maurya, Savita; Radhakrishna, M.

    2015-01-01

    Substrate oxide interfaces are of paramount importance in deciding the quality of the semiconductor devices. In this work we have studied how 200 keV proton irradiation affects the interface of a 13 nm thick, atomic layer deposited hafnium dioxide on silicon substrate. Pre- and post-irradiation electrical measurements are used to quantify the effect of proton irradiation for varying electrode geometries. Proton irradiation introduces positive charge in the oxide and at the interface of Si/HfO 2 interface. The gate current is not very much affected under positive injection since the induced positive charge is compensated by the injected electrons. Current voltage characteristics under negative bias get affected by the proton irradiation

  20. Digital hf radar observations of equatorial spread-F

    International Nuclear Information System (INIS)

    Argo, P.E.

    1984-01-01

    Modern digital ionosondes, with both direction finding and doppler capabilities can provide large scale pictures of the Spread-F irregularity regions. A morphological framework has been developed that allows interpretation of the hf radar data. A large scale irregularity structure is found to be nightward of the dusk terminator, stationary in the solar reference frame. As the plasma moves through this foehn-wall-like structure it descends, and irregularities may be generated. Localized upwellings, or bubbles, may be produced, and they drift with the background plasma. The spread-F irregularity region is found to be best characterized as a partly cloudy sky, due to the patchiness of the substructures. 13 references, 16 figures

  1. Hyperfine spectroscopic study of Laves phase HfFe2

    International Nuclear Information System (INIS)

    Belosevic-Cavor, J.; Novakovic, N.; Cekic, B.; Ivanovic, N.; Manasijevic, M.

    2004-01-01

    Hyperfine fields in HfFe 2 were measured at 181 Ta probe using the time-differential perturbed angular correlation method (TDPAC) in the temperature range 78-1200 K. Analysis of the spectra revealed two interactions with hyperfine fields of 13.82(7) T and 8.0(2) T, at 293 K. First is ascribed to the interaction at the 8a position in the cubic C15 structure. The second can be assigned to a minor amount of hexagonal C14 phase, or to an irregular position of the probe in the C15 lattice. Results of calculations using LAPW-WIEN97 are in a good agreement with experiment

  2. Dissolution and carbonation of a serpentinite: Inferences from acid attack and high P-T experiments performed in aqueous solutions at variable salinity

    International Nuclear Information System (INIS)

    Orlando, Andrea; Borrini, Daniele; Marini, Luigi

    2011-01-01

    Highlights: → In order to perform geological sequestration of CO 2 , serpentinite should be dissolved by acids or by aqueous solutions. → At atmospheric pressure serpentinite is efficaciously dissolved at 70 deg. C using acid attacks. → At higher P-T conditions, significant carbonation occurs at 30 MPa and 300 deg. C using CO 2 saturated aqueous solutions. - Abstract: Dissolution experiments on a serpentinite were performed at 70 deg. C, 0.1 MPa, in H 2 SO 4 solution, in open and closed systems, in order to evaluate the overall dissolution rate of mineral components over different times (4, 9 and 24 h). In addition, the serpentinite powder was reacted with a NaCl-bearing aqueous solution and supercritical CO 2 for 24 h at higher pressures (9-30 MPa) and temperatures (250-300 deg. C) either in a stirred reactor or in an externally-heated pressure vessel to assess both the dissolution rate of serpentinite minerals and the progress of the carbonation reaction. Results show that, at 0.1 MPa, MgO extraction from serpentinite ranges from 82% to 98% and dissolution rate varies from 8.5 x 10 -10 mole m -2 s -1 to 4.2 x 10 -9 mole m -2 s -1 . Attempts to obtain carbonates from the Mg-rich solutions by increasing their pH failed since Mg- and NH 4 - bearing sulfates promptly precipitated. On the other hand, at higher pressures, significant crystallization (5.0-10.4 wt%) of Ca- and Fe-bearing magnesite was accomplished at 30 MPa and 300 deg. C using 100 g L -1 NaCl aqueous solutions. The corresponding amount of CO 2 sequestered by crystallization of carbonates is 9.4-15.9 mole%. Dissolution rate (from 6.3 x 10 -11 mole m -2 s -1 to 1.3 x 10 -10 mole m -2 s -1 ) is lower than that obtained at 0.1 MPa and 70 deg. C but it is related to pH values much higher (3.3-4.4) than that (-0.65) calculated for the H 2 SO 4 solution. Through a thorough review of previous experimental investigations on the dissolution kinetics of serpentine minerals the authors propose adopting: (i

  3. Tsunami Arrival Detection with High Frequency (HF Radar

    Directory of Open Access Journals (Sweden)

    Donald Barrick

    2012-05-01

    Full Text Available Quantitative real-time observations of a tsunami have been limited to deep-water, pressure-sensor observations of changes in the sea surface elevation and observations of sea level fluctuations at the coast, which are essentially point measurements. Constrained by these data, models have been used for predictions and warning of the arrival of a tsunami, but to date no system exists for local detection of an actual incoming wave with a significant warning capability. Networks of coastal high frequency (HF-radars are now routinely observing surface currents in many countries. We report here on an empirical method for the detection of the initial arrival of a tsunami, and demonstrate its use with results from data measured by fourteen HF radar sites in Japan and USA following the magnitude 9.0 earthquake off Sendai, Japan, on 11 March 2011. The distance offshore at which the tsunami can be detected, and hence the warning time provided, depends on the bathymetry: the wider the shallow continental shelf, the greater this time. We compare arrival times at the radars with those measured by neighboring tide gauges. Arrival times measured by the radars preceded those at neighboring tide gauges by an average of 19 min (Japan and 15 min (USA The initial water-height increase due to the tsunami as measured by the tide gauges was moderate, ranging from 0.3 to 2 m. Thus it appears possible to detect even moderate tsunamis using this method. Larger tsunamis could obviously be detected further from the coast. We find that tsunami arrival within the radar coverage area can be announced 8 min (i.e., twice the radar spectral time resolution after its first appearance. This can provide advance warning of the tsunami approach to the coastline locations.

  4. The first HF table, after heat treatment and ready to be machined in HEPCO, Arak (IRAN)

    CERN Multimedia

    Tiziano Camporesi

    2003-01-01

    The first HF support table 'load' tested by the team of people who have contributed to it from design to welding. This table will support the 240 tons of 1 HF detector and will integrate the raisers which will push it up to the beam line level. It is the first Iranian contribution to an HEP experiment.

  5. Phase transformation and precipitation in aged Ti-Ni-Hf high-temperature shape memory alloys

    International Nuclear Information System (INIS)

    Meng, X.L.; Cai, W.; Zheng, Y.F.; Zhao, L.C.

    2006-01-01

    More attention has been paid to ternary Ti-Ni-Hf high-temperature shape memory alloys (SMAs) due to their high phase transformation temperatures, good thermal stability and low cost. However, the Ti-Ni-Hf alloys have been found to have low ductility and only about 3% shape memory effect and these have hampered their applications. It is well known that there are three methods to improve the shape memory properties of high-temperature SMAs: (a) cold rolling + annealing; (b) adding another element to the alloy; (c) aging. These methods are not suitable to improve the properties of Ti-Ni-Hf alloys. In this paper, a method of conditioning Ni-rich Ti-Ni-Hf alloys as high-temperature SMAs by aging is presented. For Ni-rich Ti 80-x Ni x Hf 20 alloys (numbers indicate at.%) the phase transformation temperatures are on average increased by more than 100 K by aging at 823 K for 2 h. Especially for those alloys with Ni contents less than 50.6 at.%, the martensitic transformation start temperatures (M s ) are higher than 473 K after aging. Transmission electron microscopy shows the presence of (Ti + Hf) 3 Ni 4 precipitates after aging. Compared with the precipitation of Ti 3 Ni 4 particles in Ni-rich Ti-Ni alloys, the precipitation of (Ti + Hf) 3 Ni 4 particles in Ni-rich Ti-Ni-Hf alloys needs higher temperatures and longer times

  6. EURObservational Research Programme: the Heart Failure Pilot Survey (ESC-HF Pilot)

    DEFF Research Database (Denmark)

    Maggioni, Aldo P; Dahlström, Ulf; Filippatos, Gerasimos

    2010-01-01

    The primary objective of the new ESC-HF Pilot Survey was to describe the clinical epidemiology of outpatients and inpatients with heart failure (HF) and the diagnostic/therapeutic processes applied across 12 participating European countries. This pilot study was specifically aimed at validating...

  7. Decolourization and degradation of azo Dye, Synozol Red HF6BN ...

    African Journals Online (AJOL)

    Decolourization and degradation of azo Dye, Synozol Red HF6BN, by Pleurotus ostreatus. Sidra Ilyas, Skinder Sultan Sultan, Abdul Rehman. Abstract. The present paper focuses on the use of fungus, Pleurotus ostreatus, to decolorize and degrade azo dye, Synazol Red HF6BN. Decolorization study showed that P.

  8. New PWM method and commutation strategy for HF-link converters for fuel cells and photovoltaics

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper presents a new PWM method and commutation strategy for HF-link converters, which leads to safe commutation of the load current in the output bidirectional bridge. The proposed implementation is independent of the particular HF-link converter topology and bidirectional switch selection ...

  9. EURObservational Research Programme : The Heart Failure Pilot Survey (ESC-HF Pilot)

    NARCIS (Netherlands)

    Maggioni, Aldo P.; Dahlstrom, Ulf; Filippatos, Gerasimos; Chioncel, Ovidiu; Crespo Leiro, Marisa; Drozdz, Jaroslaw; Fruhwald, Friedrich; Gullestad, Lars; Logeart, Damien; Metra, Marco; Parissis, John; Persson, Hans; Ponikowski, Piotr; Rauchhaus, Mathias; Voors, Adriaan A.; Nielsen, Olav Wendelboe; Zannad, Faiez; Tavazzi, Luigi

    2010-01-01

    The primary objective of the new ESC-HF Pilot Survey was to describe the clinical epidemiology of outpatients and inpatients with heart failure (HF) and the diagnostic/therapeutic processes applied across 12 participating European countries. This pilot study was specifically aimed at validating the

  10. Torsemide Versus Furosemide in Patients With Acute Heart Failure (from the ASCEND-HF Trial)

    NARCIS (Netherlands)

    Mentz, Robert J.; Hasselblad, Vic; DeVore, Adam D.; Metra, Marco; Voors, Adriaan A.; Armstrong, Paul W.; Ezekowitz, Justin A.; Tang, W. H. Wilson; Schulte, Phillip J.; Anstrom, Kevin J.; Hernandez, Adrian F.; Velazquez, Eric J.; O'Connor, Christopher M.

    2016-01-01

    Furosemide is the most commonly used loop diuretic in patients with heart failure (HF) despite data suggesting potential pharmacologic and antifibrotic benefits with torsemide. We investigated patients with HF in Acute Study of Clinical Effectiveness of Nesiritide in Decompensated Heart Failure who

  11. Mechanical properties of ultra-thin HfO2 films studied by nano scratches tests

    International Nuclear Information System (INIS)

    Fu, Wei-En; Chang, Yong-Qing; Chang, Chia-Wei; Yao, Chih-Kai; Liao, Jiunn-Der

    2013-01-01

    10-nm-thick atomic layer deposited HfO 2 films were characterized in terms of wear resistance and indentation hardness to investigate the thermal annealing induced impacts on mechanical properties. The wear resistance of ultra-thin films at low loads was characterized using nano-scratch tests with an atomic force microscope. The depth of the nano-scratches decreases with increasing annealing temperature, indicating that the hardness of the annealed films increases with the annealing temperatures. Surface nanoindentation was also performed to confirm the nanoscratch test results. The hardness variation of the annealed films is due to the generation of HfSi x O y induced by the thermal annealing. X-ray photoelectron spectroscopy measurements proved that the hardness of formed HfSi x O y with increasing annealing temperatures. The existence of HfSi x O y broadens the interface, and causes the increase of the interfacial layer thickness. As a result, the surface hardness increases with the increasing HfSi x O y induced by the thermal annealing. - Highlights: ► Mechanical properties of HfO 2 films were assessed by nano-scratch and indentation. ► Scratch depth of HfO 2 films decreased with the increase of annealing temperatures. ► Nano-hardness of HfO 2 films increased with the increase of annealing temperatures

  12. Nanomechanical study of amorphous and polycrystalline ALD HfO2 thin films

    Science.gov (United States)

    K. Tapily; J.E. Jakes; D. Gu; H. Baumgart; A.A. Elmustafa

    2011-01-01

    Thin films of hafnium oxide (HfO2) were deposited by atomic layer deposition (ALD). The structural properties of the deposited films were characterised by transmission electron microscopy (TEM) and X-ray diffraction (XRD). We investigated the effect of phase transformations induced by thermal treatments on the mechanical properties of ALD HfO

  13. Assimilative model for ionospheric dynamics employing delay, Doppler, and direction of arrival measurements from multiple HF channels

    Science.gov (United States)

    Fridman, Sergey V.; Nickisch, L. J.; Hausman, Mark; Zunich, George

    2016-03-01

    We describe the development of new HF data assimilation capabilities for our ionospheric inversion algorithm called GPSII (GPS Ionospheric Inversion). Previously existing capabilities of this algorithm included assimilation of GPS total electron content data as well as assimilation of backscatter ionograms. In the present effort we concentrated on developing assimilation tools for data related to HF propagation channels. Measurements of propagation delay, angle of arrival, and the ionosphere-induced Doppler from any number of known propagation links can now be utilized by GPSII. The resulting ionospheric model is consistent with all assimilated measurements. This means that ray tracing simulations of the assimilated propagation links are guaranteed to be in agreement with measured data within the errors of measurement. The key theoretical element for assimilating HF data is the raypath response operator (RPRO) which describes response of raypath parameters to infinitesimal variations of electron density in the ionosphere. We construct the RPRO out of the fundamental solution of linearized ray tracing equations for a dynamic magnetoactive plasma. We demonstrate performance and internal consistency of the algorithm using propagation delay data from multiple oblique ionograms (courtesy of Defence Science and Technology Organisation, Australia) as well as with time series of near-vertical incidence sky wave data (courtesy of the Intelligence Advanced Research Projects Activity HFGeo Program Government team). In all cases GPSII produces electron density distributions which are smooth in space and in time. We simulate the assimilated propagation links by performing ray tracing through GPSII-produced ionosphere and observe that simulated data are indeed in agreement with assimilated measurements.

  14. Spectro-photometric determination of niobium in Nb-Ti alloy using in-situ separation of Ti by masking with H3PO4

    International Nuclear Information System (INIS)

    Ghosh, Prasun; Dutta, M.; Jat, J.R.; Reddy, G.B.; Balaji Rao, Y.; Subba Rao, Y.

    2016-01-01

    The present paper details a simple procedure for the determination of Nb content in Nb-Ti alloy. The method involves dissolution of alloy in mixture of HNO 3 and HF followed by fuming with H 2 SO 4 . Subsequently, solution is taken for UV-Vis Spectro-photometric measurement after addition of Conc. H 3 PO 4 and H 2 O 2 . Hydrogen peroxide is added as coloring agent. Hydrogen peroxide (H 2 O 2 ) is known to form yellow color peroxo complex with both Niobium and Titanium in sulfuric acid medium and thus Ti will interfere with Nb in absorbance measurement. In view of this practical difficulty, in-situ separation of Ti during measurement has been resorted by masking Ti using Conc. H 3 PO 4 . Standard synthetic sample solution of Nb-Ti was prepared having Niobium and titanium in the ratio of 60:40, 50:50 and 40:60. Quantitative measurement of Niobium was carried out by UV-Visible spectrophotometer at 365 nm. The interference of titanium is prominent from the obtained Niobium concentration. Different ratios of H 3 PO 4 and H 2 SO 4 tried to arrive at optimum ratio to eliminate titanium interference and results are as shown. Quantitative measurement of Niobium was carried out at 355 nm as absorption maxima shifted from 365 nm to 355 nm in presence of phosphoric acid. Results show a good agreement with synthetic standard at 80:20 sulfuric to phosphoric acid ratio

  15. Doppler shift simulation of scattered HF signals during the Tromsø HF pumping experiment on 16 February 1996

    Directory of Open Access Journals (Sweden)

    T. D. Borisova

    Full Text Available Comparisons between bistatic scatter measurements and simulation results during the Tromsø HF pumping experiment on 16 February 1996 are made. Doppler measurements of an HF diagnostic signal scattered from the field-aligned irregularities (FAIs in the auroral E-region were carried out on the London – Tromsø – St. Petersburg path at 9410 kHz from 21:00 to 22:00 UT. The scattered signals were observed both from natural and artificial ionospheric irregularities located in the vicinity of Tromsø. To simulate the Doppler frequency shifts, fd , of scattered signals, a radio channel model, named CONE, was developed. The model allows for ray tracing, group and phase paths, and Doppler frequency shift calculations. The calculated Doppler shifts were analyzed for dependence on the magnitude and direction of plasma velocities in the scattering volume. It was found that the velocity components in the north-south direction are crucial for explaining the Doppler frequency shifts of the scattered diagnostic signals. To simulate fd , real velocities obtained from the EISCAT UHF radar at an altitude of 278 km and from the digital all-sky imager during the experiment were employed. The simulation results of Doppler frequency shift variations with time are in reasonable agreement with the experimental Doppler shifts of scattered signals on the London – Tromsø – St. Petersburg path.

    Key words. Ionosphere (active experiments; ionospheric irregularities Radio science (ionospheric propagation

  16. Oxidation behavior of TiC, ZrC, and HfC dispersed in oxide matrices

    International Nuclear Information System (INIS)

    Arun, R.; Subramanian, M.; Mehrotra, G.M.

    1990-01-01

    The oxidation behavior of hot pressed TiC-Al 2 O 3 , TiC-ZrO 2 , ZrC-ZrO 2 , and HfC-HfO 2 composites has been investigated at 1273 K. The oxidation of TiC, ZrC, and HfC in hot-pressed composites containing ZrO 2 and HfO 2 has been found to be extremely rapid. The kinetics of oxidation of TiC and a 90 wt% TiC-Al 2 O 3 composite appear to be faster compared to that of pure TiC. X-ray diffraction results for hot-pressed ZrC-HfO 2 and HfC-HfO 2 composites indicate partial stabilization of tetragonal ZrO 2 and HfO 2 phases in these composites

  17. TD-S-HF single determinantal reaction theory and the description of many-body processes, including fission

    International Nuclear Information System (INIS)

    Griffin, J.J.; Lichtner, P.C.; Dworzecka, M.; Kan, K.K.

    1979-01-01

    The restrictions implied for the time dependent many-body reaction theory by the (TDHF) single determinantal assumption are explored by constructive analysis. A restructured TD-S-HF reaction theory is modelled, not after the initial-value form of the Schroedinger reaction theory, but after the (fully equivalent) S-matrix form, under the conditions that only self-consistent TDHF solutions occur in the theory, every wave function obeys the fundamental statistical interpretation of quantum mechanics, and the theory reduces to the exact Schroedinger theory for exact solutions which are single determinantal. All of these conditions can be accomodated provided that the theory is interpreted on a time-averaged basis, i.e., physical constants of the Schroedinger theory which are time-dependent in the TDHF theory, are interpreted in TD-S-HF in terms of their time averaged values. The resulting reaction theory, although formulated heuristically, prescribes a well defined and unambiguous calculational program which, although somewhat more demanding technically than the conventional initial-value TDHF method, is nevertheless more consonant with first principles, structurally and mechanistically. For its physical predictions do not depend upon the precise location of the distant measuring apparatus, and are in no way influenced by the spurious cross channel correlations which arise whenever the description of many reaction channels is imposed upon one single-determinantal solution. For nuclear structure physics, the TDHF-eigenfunctions provide the first plausible description of exact eigenstates in the time-dependent framework; moreover, they are unencumbered by any restriction to small amplitudes. 14 references

  18. Modified structure of graphene oxide by investigation of structure ...

    Indian Academy of Sciences (India)

    In this regard, GO was produced using the modified. Hummers method and ... erated in some regions due to hydrogen bonding between functional groups. Trapped water .... flakes were reacted with strong acid solution of H2SO4 and. HNO3.

  19. Structure, optical properties and thermal stability of HfErO films deposited by simultaneous RF and VHF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.Y. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Nanjing University of Posts and Telecommunications, School of Tongda, Nanjing (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); He, H.J.; Zhang, Z.; Jin, C.G.; Yang, Y.; Wang, Y.Y.; Ye, C. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Zhuge, L.J. [Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Soochow University, Analysis and Testing Center, Suzhou (China); Wu, X.M. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Chinese Academy of Sciences, State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Shanghai (China)

    2015-01-23

    HfErO films are deposited on Si substrates by simultaneous radio frequency (RF) and very high frequency (VHF) magnetron sputtering technique. The content of the doped ingredient of Er and the body composition of HfO{sub x} are, respectively, controlled through the VHF and RF powers. Low content of Er doping in the HfErO films can be achieved, because the VHF source of 27.12 MHz has higher ion energy and lower ion flux than the RF source resulting in low sputtering rate in the magnetron sputtering system. The structure, optical properties and thermal stability of the HfErO films are investigated in this work. Results show that the doped content of Er is independently controlled by the VHF power. The oxygen vacancies are created by the Er incorporation. The hafnium in the HfErO films forms mixed valence of Hf{sup 2+} and Hf{sup 4+}. The HfErO films are composed with the structures of HfO{sub 2}, HfO and ErO{sub x}, which can be optimized through the VHF power. At high VHF power, the Hf-Er-O bonds are formed, which demonstrates that the Er atoms are doped into the lattice of HfO{sub 2} in the HfErO films. The HfErO films have bad thermal stability as the crystallization temperature decreases from 900 to 800 C. After thermal annealing, cubic phase of HfO{sub 2} are stabilized, which is ascribed to the oxygen vacancies creation by the Er incorporation. The optical properties such as the refractive index and the optical band gap of the HfErO films are optimized by the VHF power. (orig.)

  20. Structure, optical properties and thermal stability of HfErO films deposited by simultaneous RF and VHF magnetron sputtering

    International Nuclear Information System (INIS)

    Zhang, H.Y.; He, H.J.; Zhang, Z.; Jin, C.G.; Yang, Y.; Wang, Y.Y.; Ye, C.; Zhuge, L.J.; Wu, X.M.

    2015-01-01

    HfErO films are deposited on Si substrates by simultaneous radio frequency (RF) and very high frequency (VHF) magnetron sputtering technique. The content of the doped ingredient of Er and the body composition of HfO x are, respectively, controlled through the VHF and RF powers. Low content of Er doping in the HfErO films can be achieved, because the VHF source of 27.12 MHz has higher ion energy and lower ion flux than the RF source resulting in low sputtering rate in the magnetron sputtering system. The structure, optical properties and thermal stability of the HfErO films are investigated in this work. Results show that the doped content of Er is independently controlled by the VHF power. The oxygen vacancies are created by the Er incorporation. The hafnium in the HfErO films forms mixed valence of Hf 2+ and Hf 4+ . The HfErO films are composed with the structures of HfO 2 , HfO and ErO x , which can be optimized through the VHF power. At high VHF power, the Hf-Er-O bonds are formed, which demonstrates that the Er atoms are doped into the lattice of HfO 2 in the HfErO films. The HfErO films have bad thermal stability as the crystallization temperature decreases from 900 to 800 C. After thermal annealing, cubic phase of HfO 2 are stabilized, which is ascribed to the oxygen vacancies creation by the Er incorporation. The optical properties such as the refractive index and the optical band gap of the HfErO films are optimized by the VHF power. (orig.)

  1. Structural investigations of zirconia powders obtained by hf-plasmochemical denitration

    International Nuclear Information System (INIS)

    Dedov, N.V.; Ivanov, Yu.F.; Dorda, F.A.; Paul', A.V.; Zav'yalov, A.V.; Koneva, N.A.; Korobtsev, V.P.; Kutyavin, E.M.; Mazin, V.I.; Matyukha, V.A.

    1992-01-01

    Results are presented of structural and physicochemical investigations of unstabilized and stabilized (using yttria, magnesia, calcium oxide and alumina) zirconia, obtained from nitrate solutions on pilot HF-plasmochemical equipment with an electric rating of 63 kW. The phase composition of the ultradispersed powder is shown. Morphological and grain-size analyses were carried out on the EM-125K electron diffraction microscope. specimens were prepared by applying powder to a carbon film obtained in a VUP-4 vacuum cell. The phase composition was studied by x-ray analysis on the DRON-3 diffractometer. These studies established that the main morphological constituents of the ZrO 2 powder are polycrystalline hollow spheres and fragments of films. The average sizes (diameter) of the spheres in 0.77 μ (mean square deviation σ n = 0.57μ) and for the grains in them 31 nm (σ n = 9.5 nm). There exists a certain correlation between the dimensions of the polycrystalline spheres and their grain structure - the coarser the powders, the larger the grains observed

  2. Increase in Ice Nucleation Efficiency of Feldspars, Kaolinite and Mica in Dilute NH3 and NH4+-containing Solutions

    Science.gov (United States)

    Kumar, A.; Marcolli, C.; Luo, B.; Krieger, U. K.; Peter, T.

    2017-12-01

    Semivolatile species present in the atmosphere are prone to adhere to mineral dust particle surfaces during long range transport, and could potentially change the particle surface properties and its ice nucleation (IN) efficiency. Immersion freezing experiments were performed with microcline (K-feldspar), known to be highly IN active, suspended in aqueous solutions of ammonia, (NH4)2SO4, NH4HSO4, NH4NO3, NH4Cl, Na2SO4, H2SO4, K2SO4 and KCl to investigate the effect of solutes on the IN efficiency. Freezing of emulsified droplets investigated with a differential scanning calorimeter (DSC) showed that the heterogeneous ice nucleation temperatures deviate from the water activity-based IN theory, describing heterogeneous ice nucleation temperatures as a function of solution water activity by a constant offset with respect to the ice melting point curve (Zobrist et al. 2008). IN temperatures enhanced up to 4.5 K were observed for very dilute NH3 and NH4+-containing solutions while a decrease was observed as the concentration was further increased. For all solutes with cations other than NH4+, the IN efficiency decreased. An increase of the IN efficiency in very dilute NH3 and NH4+-containing solutions followed by a decrease with increasing concentration was also observed for sanidine (K-feldspar) and andesine (Na/Ca-feldspar). This is an important indication towards specific chemical interactions between solutes and the feldspar surface which is not captured by the water activity-based IN theory. A similar trend is present but less pronounced in case of kaolinite and mica, while quartz is barely affected. We hypothesize that the hydrogen bonding of NH3 molecules with surface -OH groups could be the reason for the enhanced freezing temperatures in dilute ammonia and ammonium containing solutions as they could form an ice-like overlayer providing hydrogen bonding groups for ice to nucleate on top of it. This implies to possibilities of enhanced IN efficiency, especially

  3. Design for human factors (DfHF): a grounded theory for integrating human factors into production design processes.

    Science.gov (United States)

    Village, Judy; Searcy, Cory; Salustri, Filipo; Patrick Neumann, W

    2015-01-01

    The 'design for human factors' grounded theory explains 'how' human factors (HF) went from a reactive, after-injury programme in safety, to being proactively integrated into each step of the production design process. In this longitudinal case study collaboration with engineers and HF Specialists in a large electronics manufacturer, qualitative data (e.g. meetings, interviews, observations and reflections) were analysed using a grounded theory methodology. The central tenet in the theory is that when HF Specialists acclimated to the engineering process, language and tools, and strategically aligned HF to the design and business goals of the organisation, HF became a means to improve business performance. This led to engineers 'pulling' HF Specialists onto their team. HF targets were adopted into engineering tools to communicate HF concerns quantitatively, drive continuous improvement, visibly demonstrate change and lead to benchmarking. Senior management held engineers accountable for HF as a key performance indicator, thus integrating HF into the production design process. Practitioner Summary: Research and practice lack explanations about how HF can be integrated early in design of production systems. This three-year case study and the theory derived demonstrate how ergonomists changed their focus to align with design and business goals to integrate HF into the design process.

  4. Preparation and enhanced oxidation performance of a Hf-doped single-phase Pt-modified aluminide coating

    International Nuclear Information System (INIS)

    Yang, Y.F.; Jiang, C.Y.; Yao, H.R.; Bao, Z.B.; Zhu, S.L.; Wang, F.H.

    2016-01-01

    Graphical abstract: Tiny Hf particles were successfully incorporated into Pt plating via simple electro-plating method. The hafnium particles were either nipped at Pt grain boundaries or wrapped inside Pt grains, and most of them were below 3 μm in size, showing a uniform distribution within the Pt plating. - Highlights: • A Hf-rich belt formed between outer (Ni,Pt)Al and IDZ after aluminisation. • Hf-doped coating showed much decreased mass gain and oxidation rate constant k_p. • Hf-rich belt acted as diffusion barrier by restraining diffusions of Al and W. • Degradation of β was effectively postponed by the unique Hf addition. • Hf-doped coating exhibited lighter oxide scale rumpling tendency. - Abstract: A Hf-doped β-(Ni,Pt)Al coating was prepared by co-deposition of a Pt-Hf composite plating and successive aluminisation. Then, a distinct Hf-rich belt was formed internally between the outer additive (Ni,Pt)Al coating and interdiffusion zone. An isothermal oxidation test at 1100 °C revealed a relatively lower oxidation rate constant and decreased oxide scale rumpling tendency for the Hf-doped coating during which the Hf-rich belt partly acted as an effective diffusion barrier. The unique addition of Hf into a β-(Ni,Pt)Al coating can delay the transitional oxidation period from transient alumina to stable one and postpone the degradation from β to γ'.

  5. Effects of Nitrogen Implantation on the Resistance to Localized Corrosion of Zircaloy-4 in a Chloride Solution

    International Nuclear Information System (INIS)

    Lee, Sung Joon; Kwon, Hyuk Sang; Kim, Wan; Choi, Byung Ho

    1996-01-01

    The influences of ion dose and substrate temperature on the resistance to localized corrosion of nitrogen-implanted Zircaloy-4 are examined in terms of potentiodynamic anodic polarization tests in deaerated 4M NaCl solution at 80 .deg. C. Nitrogen implantations into the Zircaloy-4 were performed under conditions of varying the ion dose from 3 x 10 17 to 1.2 x 10 18 ions/cm 2 and of maintaining the substrate temperatures respectively at 100, 200, and 300 .deg. C by controlling the current density of ion beam. The resistance to localized corrosion of Zircaloy-4 was significantly increased with increasing the ion dose when implanted at substrate temperatures above 200 .deg. C. However, it was not almost improved by implantation at 100 .deg. C. Specifically, the pitting potential increased from 350mV (vs. SCE) for the unimplanted to values of 900 to about 1400mV (vs. SCE) for the implanted alloy depending on the nitrogen dose. This significant improvement in the resistance to localized corrosion of the implanted Zircaloy-4 was found to be associate with the formation of compound layers of ZrO 2 + ZrN during the implantation. The galvanostatic anodization tests on the nitrogen-implanted Zircaloy-4 in 1M H 2 SO 4 at 20 .deg. C demonstrated that an increase in the ion dose and also in the substrate temperature increased the thickness of the compound layer of ZrO 2 + ZrN, and hence increased the pitting potential of the alloy. The low resistance to localized and general corrosion of the alloy implanted at 100 .deg. C was attributed to the increase in surface defect density and also to thinner implanted layer compared with those formed at higher temperatures

  6. In-situ atomic layer deposition growth of Hf-oxide

    International Nuclear Information System (INIS)

    Karavaev, Konstantin

    2010-01-01

    We have grown HfO 2 on Si(001) by atomic layer deposition (ALD) using HfCl 4 , TEMAHf, TDMAHf and H 2 O as precursors. The early stages of the ALD were investigated with high-resolution photoelectron spectroscopy and X-ray absorption spectroscopy. We observed the changes occurring in the Si 2p, O 1s, Hf 4f, Hf 4d, and Cl 2p (for HfCl 4 experiment) core level lines after each ALD cycle up to the complete formation of two layers of HfO 2 . The investigation was carried out in situ giving the possibility to determine the properties of the grown film after every ALD cycle or even after a half cycle. This work focused on the advantages in-situ approach in comparison with ex-situ experiments. The study provides to follow the evolution of the important properties of HfO 2 : contamination level, density and stoichiometry, and influence of the experimental parameters to the interface layer formation during ALD. Our investigation shows that in-situ XPS approach for ALD gives much more information than ex-situ experiments. (orig.)

  7. In-situ atomic layer deposition growth of Hf-oxide

    Energy Technology Data Exchange (ETDEWEB)

    Karavaev, Konstantin

    2010-06-17

    We have grown HfO{sub 2} on Si(001) by atomic layer deposition (ALD) using HfCl{sub 4}, TEMAHf, TDMAHf and H{sub 2}O as precursors. The early stages of the ALD were investigated with high-resolution photoelectron spectroscopy and X-ray absorption spectroscopy. We observed the changes occurring in the Si 2p, O 1s, Hf 4f, Hf 4d, and Cl 2p (for HfCl{sub 4} experiment) core level lines after each ALD cycle up to the complete formation of two layers of HfO{sub 2}. The investigation was carried out in situ giving the possibility to determine the properties of the grown film after every ALD cycle or even after a half cycle. This work focused on the advantages in-situ approach in comparison with ex-situ experiments. The study provides to follow the evolution of the important properties of HfO{sub 2}: contamination level, density and stoichiometry, and influence of the experimental parameters to the interface layer formation during ALD. Our investigation shows that in-situ XPS approach for ALD gives much more information than ex-situ experiments. (orig.)

  8. Preparation, structure and properties of hafnium compounds in the system Hf-C-N-O

    International Nuclear Information System (INIS)

    Brundiers, G.D.

    1975-08-01

    Highly dense, homogenous and single phase hafnium carbonitride samples (with low oxygen content) were prepared in the whole concentration range of the ternary cubic carbonitrides. Stoichiometric hafnium oxicarbides were also prepared within the range of solubility. The procedure involved the hot pressing of powders of HfC, HfN, Hf, Hf-Oxide and carbon at temperatures of 3,000 0 C and pressures up to 550 kpf/cm 2 using a novel technique. Small single crystals of slightly substoichiometric HfN were also repared. The densification of the powders was studied as a function of the non-metal concentration. Carbonitrides with N/Hf ratio of 0.37 were prepared in a high temperature autoclave operating at medium pressures by the reaction of HfC with nitrogen. All the samples were characterized by density measurements, chemical, X-ray and metallographic analysis and in some cases with the aid of quantitative metallography and microprobe analysis. Typical properties investigated were lattice parameter, thermal expansion, microhardness and electrical resistivity as function of the non-metal content. For specific concentrations extreme values in the properties are attained. With the aid of the valence electron concentration (VEC) parameter, the properties can be correlated with the density of states of electrons at the Fermi level. (orig./HK) [de

  9. Effects of HfO{sub 2}/Co interface and Co/HfO{sub 2} interface on anomalous Hall behavior in perpendicular Co/Pt multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Shao-Long [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Yang, Guang [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Teng, Jiao, E-mail: tengjiao@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Guo, Qi-Xun; Liu, Yi-Wei; Li, Xu-Jing [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yu, Guang-Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2017-07-01

    Highlights: • Anomalous Hall effect in perpendicular Co/Pt multilayers is studied. • Thermally stable AHE feature is obtained in [Pt/Co]{sub 3}/HfO{sub 2}/Pt multilayers. • Good thermal stability is due to enhanced intrinsic and side-jump contributions. - Abstract: Effects of the HfO{sub 2}/Co interface and the Co/HfO{sub 2} interface on thermal stability of anomalous Hall effect (AHE) in perpendicular Co/Pt multilayers have been studied. It is observed that thermally stable AHE behavior cannot be obtained in perpendicular Co/Pt multilayers with the HfO{sub 2}/Co interface, mainly due to Co-Pt interdiffusion during annealing. In contrast, thermally stable AHE feature is observed in perpendicular Co/Pt multilayers with the Co/HfO{sub 2} interface despite Co-Pt interdiffusion, which is owing to the enhancement of the side jump and intrinsic contributions to the AHE through interfacial modification after annealing.

  10. A comparative study of amorphous InGaZnO thin-film transistors with HfOxNy and HfO2 gate dielectrics

    International Nuclear Information System (INIS)

    Zou, Xiao; Tong, Xingsheng; Fang, Guojia; Yuan, Longyan; Zhao, Xingzhong

    2010-01-01

    High-κ HfO x N y and HfO 2 films are applied to amorphous InGaZnO (a-IGZO) devices as gate dielectric using radio-frequency reactive sputtering. The electrical characteristics and reliability of a-IGZO metal–insulator–semiconductor (MIS) capacitors and thin-film transistors (TFTs) are then investigated. Experimental results indicate that the nitrogen incorporation into HfO 2 can effectively improve the interface quality and enhance the reliability of the devices. Electrical properties with an interface-state density of 5.2 × 10 11 eV −1 cm −2 , capacitance equivalent thickness of 1.65 nm, gate leakage current density of 3.4 × 10 −5 A cm −2 at V fb +1 V, equivalent permittivity of 23.6 and hysteresis voltage of 110 mV are obtained for an Al/HfO x N y /a-IGZO MIS capacitor. Superior performance of HfO x N y /a-IGZO TFTs has also been achieved with a low threshold voltage of 0.33 V, a high saturation mobility of 12.1 cm 2 V −1 s −1 and a large on–off current ratio up to 7 × 10 7 (W/L = 500/20 µm) at 3 V

  11. Comparison of 14 MeV isomer production of 178m2Hf and 179m2Hf using Feshbach-Kerman-Koonin and exciton preequilibrium models

    International Nuclear Information System (INIS)

    Chadwick, M.B.; Young, P.G.

    1993-01-01

    The 178m2 Hf(16+) isomeric state has a 31-yr half life and could pose serious radioactive problems in nuclear fusion reactors if its production in 14 MeV neutron-induced reactions is significant. We present statistical/preequilibrium model calculations for the production of this isomer in the 179 Hf(n, 2n) 178m2 Hf reaction, as well as the 25-days 12.5 - isomer in the 179 Hf(n,n') 179m2 Hf reaction, using two different preequilibrium models: the exciton model and the Feshbach-Kerman-Koonin (FKK) theory. Our calculations which use the exciton model agree well with measurements, but those with the FKK theory underestimate measurements. Our calculations axe the first to probe angular momentum transfer effects in the FKK theory and suggest that, as it is presently applied, high spin-transfer reactions are underestimated. We suggest modifications to the FKK statistical averaging procedure which may result in an improved agreement with experiment

  12. Hf-Nd isotope decoupling in the oceanic lithosphere: constraints from spinel peridotites from Oahu, Hawaii

    Science.gov (United States)

    Bizimis, Michael; Sen, Gautam; Salters, Vincent J. M.

    2004-01-01

    We present a detailed geochemical investigation on the Hf, Nd and Sr isotope compositions and trace and major element contents of clinopyroxene mineral separates from spinel lherzolite xenoliths from the island of Oahu, Hawaii. These peridotites are believed to represent the depleted oceanic lithosphere beneath Oahu, which is a residue of a MORB-related melting event some 80-100 Ma ago at a mid-ocean ridge. Clinopyroxenes from peridotites from the Salt Lake Crater (SLC) show a large range of Hf isotopic compositions, from ɛHf=12.2 (similar to the Honolulu volcanics series) to extremely radiogenic, ɛHf=65, at nearly constant 143Nd/ 144Nd ratios ( ɛNd=7-8). None of these samples show any isotopic evidence for interaction with Koolau-type melts. A single xenolith from the Pali vent is the only sample with Hf and Nd isotopic compositions that falls within the MORB field. The Hf isotopes correlate positively with the degree of depletion in the clinopyroxene (e.g. increasing Mg#, Cr#, decreasing Ti and heavy REE contents), but also with increasing Zr and Hf depletions relative to the adjacent REE in a compatibility diagram. The Lu/Hf isotope systematics of the SLC clinopyroxenes define apparent ages of 500 Ma or older and these compositions cannot be explained by mixing between any type of Hawaiian melts and the depleted Pacific lithosphere. Metasomatism of an ancient (e.g. 1 Ga or older) depleted peridotite protolith can, in principle, explain these apparent ages and the Nd-Hf isotope decoupling, but requires that the most depleted samples were subject to the least amount of metasomatism. Alternatively, the combined isotope, trace and major element compositions of these clinopyroxenes are best described by metasomatism of the 80-100 Ma depleted oceanic lithosphere by melts products of extensive mantle-melt interaction between Honolulu Volcanics-type melts and the depleted lithosphere.

  13. DIRECT DETERMINATION OF THE HF/H{sub 2} ABUNDANCE RATIO IN INTERSTELLAR GAS

    Energy Technology Data Exchange (ETDEWEB)

    Indriolo, Nick; Neufeld, D. A. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Seifahrt, A. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Richter, M. J. [Department of Physics, University of California Davis, Davis, CA 95616 (United States)

    2013-02-20

    We report the first detection of the v = 1-0, R(0) ro-vibrational transition of HF at 2.499385 {mu}m arising from interstellar gas. The line is seen in absorption toward three background sources-HD 154368, Elias 29, and AFGL 2136 IRS 1-all of which have reported H{sub 2} column densities determined from observations of H{sub 2}. This allows for the first direct determination of the HF/H{sub 2} abundance ratio. We find values of N(HF)/N(H{sub 2}) = 1.15 Multiplication-Sign 10{sup -8} and 0.69 Multiplication-Sign 10{sup -8} for HD 154368 and Elias 29, respectively. The sight line toward AFGL 2136 IRS 1 also shows absorption from the v = 1-0, R(1) transition of HF, indicating warm, dense (n {sub H} {approx}> 10{sup 9} cm{sup -3}) gas, likely very close to the central protostar. Ascribing portions of the HF absorption to warm and cold gas, we find N(HF)/N(H{sub 2}) = (1.7-2.9) Multiplication-Sign 10{sup -8} and (0.33-0.58) Multiplication-Sign 10{sup -8} for the two components, respectively. Except for the warm component toward AFGL 2136 IRS 1, all observed HF/H{sub 2} ratios are well below N(HF)/N(H{sub 2}) = 3.6 Multiplication-Sign 10{sup -8}, the value predicted if nearly all gas phase fluorine is in the form of HF. Models of fluorine chemistry that account for depletion onto grains are able to reproduce the results toward HD 154368, but not in the cold, dense gas toward AFGL 2136 IRS 1 and Elias 29. Most likely, some combinations of simplifying assumptions made in the chemical models are responsible for these discrepancies.

  14. Mechanisms and selectivity for etching of HfO2 and Si in BCl3 plasmas

    International Nuclear Information System (INIS)

    Wang Chunyu; Donnelly, Vincent M.

    2008-01-01

    The authors have investigated plasma etching of HfO 2 , a high dielectric constant material, and poly-Si in BCl 3 plasmas. Etching rates were measured as a function of substrate temperature (T s ) at several source powers. Activation energies range from 0.2 to 1.0 kcal/mol for HfO 2 and from 0.8 to 1.8 kcal/mol for Si, with little or no dependence on source power (20-200 W). These low activation energies suggest that product removal is limited by chemical sputtering of the chemisorbed Hf or Si-containing layer, with a higher T s only modestly increasing the chemical sputtering rate. The slightly lower activation energy for HfO 2 results in a small improvement in selectivity over Si at low temperature. The surface layers formed on HfO 2 and Si after etching in BCl 3 plasmas were also investigated by vacuum-transfer x-ray photoelectron spectroscopy. A thin boron-containing layer was observed on partially etched HfO 2 and on poly-Si after etching through HfO 2 films. For HfO 2 , a single B(1s) feature at 194 eV was ascribed to a heavily oxidized species with bonding similar to B 2 O 3 . B(1s) features were observed for poly-Si surfaces at 187.6 eV (B bound to Si), 189.8 eV, and 193 eV (both ascribed to BO x Cl y ). In the presence of a deliberately added 0.5% air, the B-containing layer on HfO 2 is largely unaffected, while that on Si converts to a thick layer with a single B(1s) peak at 194 eV and an approximate stoichiometry of B 3 O 4 Cl

  15. 182Hf: a new stopwatch for the early solar system

    International Nuclear Information System (INIS)

    Norman, E.B.; Schramm, D.N.

    1983-01-01

    It is now well established that live 26 Al (t/sub 1/2/ = 7.2 x 10 5 yr) and 107 Pd (t/sub 1/2/ = 6.5 x 10 6 yr) were present in the early solar system. Thus, the nucleosynthetic vent (supernova) responsible for the production of these nuclei must have occurred no more than a few million years prior to the formation of solid bodies. It is possible that this event also produced the 129 I known to be present in the early solar system. However, the last event to contribute 244 Pu to the solar system occurred approx. 10 8 yr prior to the time of solidification. This latter time scale is also consistent with the lack of evidence for a 247 Cm chronometer. In this letter, we propose that 182 Hf (t/sub 1/2/ = 9 x 10 6 yr) can resolve the question of whether heavy-element non-actinide nucleosynthesis occurred during the 26 Al-producing event. The answer to this question will help to clarify the chronology of the formation of the solar system and will help to determine the astrophysical sites of heavy-element nucleosynthesis

  16. Multi-quasi-particle states in 173Hf

    International Nuclear Information System (INIS)

    Fabricius, B.; Dracoulis, G.D.; Kibedi, T.; Stuchbery, A.E.; Baxter, A.M.

    1991-01-01

    Rotational bands built on 1, 3 and 5 quasi-particle (qp) states in 173 Hf have been populated to medium and high spins through the 160 Gd( 18 O, 5n) reaction. The 1qp bands, previously identified as the 1/2 - [521], 5/2 - [512] and 7/2 + [633] (mixed i 13/2 ) Nilsson configurations, have been extended past the first back-bend and show different alignment properties, possibly originating from deformation differences. The multi-particle states were identified from excitation energies, the properties of their associated band structures and decay patterns. The 3qp states are the previously known K π =19/2 + and 23/2 - isomeric states originating from the 7/2 + [633] quasi-neutron coupled to the 6 + and 8 - , 2-quasi-proton excitations and a K π =(13/2 + ) state possibly containing the three lowest quasi-neutrons. A 5qp state with K π =(29/2 - ) was identified as the same three lowest lying quasi-neutrons coupled to the 8 - , 2-quasi-proton excitation. The low excitation energies of these two related 3- and 5-quasi-particle states implies a reduced neutron pairing gap, which can be attributed to the effect of blocking. (orig.)

  17. Multi-quasi-particles states in 173Hf

    International Nuclear Information System (INIS)

    Fabricius, B.; Dracoulis, G.D.; Kibedi, T.; Stuchbery, A.E.; Baxter, A.M.

    1990-10-01

    Rotational bands built on 1, 3 and 5 quasi-particle (qp) states in 173 Hf have been populated to medium and high spins through the 160 Gd ( 18 O,5n) reaction. The 1qp bands, previously identified as the 1/2 - [521], 5/2 - [512] and 7/2 + [633] (mixed i 1 3 /2 ) Nilsson configurations, have been extended past the first back-bend and show different alignment properties, possibly originating from deformation differences. The multi-particle states were identified from excitation energies, the properties of their associated band structures and decay patterns. The 3 qp states are the previously known K π 19/2 + and 23/2 - isomeric states originating from the 7/2 + [633] quasi-neutron coupled to the 6 + and 8 - , 2-quasi-proton excitations and a K π = (13/2 + ) state possibly containing the three lowest quasi-neutrons. A 5 qp state with K π = (29/2 - ) was identified as the same three lowest lying quasi-neutrons coupled to the 8 - , 2-quasi-proton excitation. The low excitation energies of these two related 3- and 5-quasi-particle states implies a reduced neutron pairing gap, which can be attributed to the effect of blocking. 28 refs., 2 tabs., 9 figs

  18. Three band crossings in the yrast structure of 162Hf

    International Nuclear Information System (INIS)

    Bingham, C.R.; Riedinger, L.L.; Courtney, L.H.

    1988-01-01

    The yrast sequence of 162 Hf has been observed up to a level tentatively assigned as 38 + and reveals a continuing rotational character up to that spin. Sharp backbends at rotational frequencies of 0.27 and 0.42 MeV/ℎ are attributed to isub(13/2) neutron and hsub(11/2) proton alignments, respectively. A gradual increase in the aligned angular momentum of the yrast levels between these two sharp backbends is attributed to the rotational alignment of a pair of negative parity quasineutrons (mostly hsub(9/2) in character). The interpretation of this effect is supported by the failure of the negative parity bands, which already contain this aligned hsub(9/2) neutron, to gain alignment in the same rotational frequency range. While the alignment of the hsub(9/2) quasineutrons has been predicted in the cranked shell model to occur in the rare-earth region with a large interaction strength, this represents the first clear observation of such a band crossing. (author)

  19. Feasibility study of data transmission via HF link from a small UAV platform

    OpenAIRE

    Enander, Filip

    2017-01-01

    The High Frequency (HF) band, 3-30 MHz, is used when no infrastructure for long-range communications is available. New technology, such as digital signal processing enables higher data rate in the HF band, which in 2000s has resulted in increased commercial use. Reflection of radio waves in the ionosphere allows for beyond horizon communication, and are a unique property of the HF band. However, properties of the ionosphere are highly dependent of radiation from the sun, which varies with geo...

  20. Effective moments of inertia and spin cut off parameters in Hf isotopes

    International Nuclear Information System (INIS)

    Razavi, R.; Sharifzadeh, N.; Farahmand, M.R.

    2011-01-01

    In all statistical theories the nuclear level density is the most characteristic quantity and plays a major role in the study of nuclear structure. Most experimental data on nuclear level density have been analyzed with analytical functions of the level density. On the basis of statistical models, the effective moments of inertia and spin cut off parameters have been determined for 176 Hf, 178 Hf and 180 Hf nuclei from extensive and complete level schemes and neutron resonance densities in low excitation energy levels. Then, moments of inertia of these nuclei have been determined by nuclear rotational model. The results have been compared with their corresponding rigid body value

  1. Coulomb-nuclear interference measurements of hexadecapole deformations in 168Yb and 178,180Hf

    International Nuclear Information System (INIS)

    Nettles, W.G.; Mississippi Coll., Clinton; Ramayya, A.V.; Hamilton, J.H.

    1988-01-01

    Coulomb-nuclear interference studies of 168 Yb and 178,180 Hf have been carried out with alpha particles from the Pittsburgh tandem. From coupled channel fits to the data at 18 MeV for 168 Yb and 19.5 MeV for 178,180 Hf, β 4 c values of -0.030(20), -0.166(18), and -0.180(6) were obtained, respectively. These data agree with the positive M 04 value from sub-Coulomb studies of 168 Yb but with the large negative M 04 values from sub-Coulomb studies of 178,180 Hf. (author)

  2. Lu-Hf isotope systematics of fossil biogenic apatite and their effects on geochronology

    Science.gov (United States)

    Herwartz, Daniel; Münker, Carsten; Tütken, Thomas; Hoffmann, J. Elis; Wittke, Andreas; Barbier, Bruno

    2013-01-01

    Reliable methods for direct dating of biogenic apatite from pre-Pleistocene fossils are currently not available, and recent attempts using the Lu-Hf decay system yielded highly inaccurate ages for both bones and teeth. The geological processes accounting for this poor accuracy of Lu-Hf chronometry are not yet understood. Here we explore Lu-Hf systematics in fossil bones and teeth in detail, by applying five different sample digestion techniques that are tested on bones and composites of bone and sediment. Our current dataset implies that dissolution methods only slightly affect the resulting Lu-Hf ages, while clear differences between the individual digestion techniques became apparent for element concentrations. By analysing the insoluble leftovers from incomplete sample dissolution, four main reservoirs of Hf in fossil bones were identified: (1) a radiogenic end-member associated with apatite; (2) an unradiogenic end-member represented by the authigenic minerals or the embedding sediment; (3) a highly unradiogenic end-member that can be attributed to detrital zircon; and (4) a moderately soluble phase (probably a Zr(Hf)-phosphate) that yielded very low Lu/Hf but a highly radiogenic Hf isotope composition at the same time. This Zr(Hf)-phase must have been precipitated within the fossil bone sample at a late stage of burial history, thereby incorporating radiogenic 176Hf released from apatite surfaces over geological timescales. A second focus of our study is the effect of different sediment matrices and of crystal size on the preservation of pristine Lu-Hf isotope compositions in bioapatite. Because near-depositional Lu-Hf ages of phosphate fossils have previously been reported for the London Clay (England) and a calcareous marl from Tendaguru (Tanzania), we herein investigate specimens fossilised in carbonate matrices (calcareous marl from Oker, Germany; carbonate concretions from the Santana Formation, Brazil; carbonate from the Eifel, Germany) and argillaceous

  3. Preparation, microstructure and magnetic properties of Sm(Co,Hf){sub 7}/Co nanocomposite particles by polyol method

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Shao-Jing; Duan, Xiu-Li; Han, Xu-Hao; Sun, Ji-Bing, E-mail: hbgdsjb@126.com; Chi, Xiang; Cui, Chun-Xiang

    2017-02-01

    Hard/soft Sm-Co/Co nanocomposite particles were prepared by reducing CoCl{sub 2}·6H{sub 2}O in the solution containing ball-milled Sm(Co, Hf){sub 7} particles by a simple polyol method with ethylene glycol as the solvent. Phase composition, microstructure and magnetic properties of the particles were analyzed by XRD, TEM (HRTEM) and VSM, respectively. It has been found that Sm-Co/Co core/shell structure is formed in which the Co shell is 3–5 nm in thickness and mainly exists in hcp-Co phase. At the same time, fcc-Co tends to nucleate and grow independently between Sm-Co particles. The formation mechanism of Sm-Co/Co composite particles is discussed and corresponding model is established. Sm-Co/Co composite particles perform obvious remanence enhancement effects especially after being heated at 450 °C for 15 min.

  4. Optical properties of a HfO2/Si stack with a trace amount of nitrogen incorporation

    Science.gov (United States)

    Ye, Li; Tingting, Jiang; Qingqing, Sun; Pengfei, Wang; Shijin, Ding; Wei, Zhang

    2012-03-01

    HfO2 films were deposited by atomic layer deposition through alternating pulsing of Hf[N(C2H5)(CH3)]4 and H2O2. A trace amount of nitrogen was incorporated into the HfO2 through ammonia annealing. The composition, the interface stability of the HfO2/Si stack and the optical properties of the annealed films were analyzed to investigate the property evolution of HfO2 during thermal treatment. With a nitrogen concentration increase from 1.41 to 7.45%, the bandgap of the films decreased from 5.82 to 4.94 eV.

  5. Oxide or carbide nanoparticles synthesized by laser ablation of a bulk Hf target in liquids and their structural, optical, and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Semaltianos, N. G., E-mail: nsemaltianos@yahoo.com [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Friedt, J.-M.; Blondeau-Patissier, V.; Combe, G. [Dépt. Temps-Fréquence, Femto-st, UMR CNRS 6174, Université de Franche-Comté, Besançon 25030 (France); Chassagnon, R. [Laboratoire Interdisciplinaire Carnot De Bourgogne, ICB UMR CNRS 6303, Université de Bourgogne Franche-Comté, Dijon 21078 (France); Moutarlier, V. [UTINAM, UMR CNRS 6213, Université de Franche-Comté, Besançon 25030 (France); Assoul, M.; Monteil, G. [Dépt. Mécanique Appliquée, Femto-st, UMR CNRS 6174, Université de Franche-Comté, Besançon 25030 (France)

    2016-05-28

    Laser ablation of a bulk Hf target in deionized (DI) water, ethanol, or toluene was carried out for the production of nanoparticles' colloidal solutions. Due to the interaction of the ablation plasma plume species with the species which are produced by the liquid decomposition at the plume-liquid interface, hafnia (HfO{sub 2}) nanoparticles are synthesized in DI water, hafnium carbide (HfC) nanoparticles in toluene, and a mixture of these in ethanol. The hafnia nanoparticles are in the monoclinic low temperature phase and in the tetragonal and fcc high temperature phases. Their size distribution follows log-normal function with a median diameter in the range of 4.3–5.3 nm. Nanoparticles synthesized in DI water have band gaps of 5.6 and 5.4 eV, in ethanol 5.72 and 5.65 eV (using low and high pulse energy), and in toluene 3 eV. The values for the relative permittivity in the range of 7.74–8.90 were measured for hafnia nanoparticles' thin films deposited on substrates by drop-casting (self-assembled layers) in parallel plate capacitor structures.

  6. Effect of γ-dose on the crystal structure and leaching behavior of TiO2 matrix labeled with 181Hf/181Ta tracer

    International Nuclear Information System (INIS)

    Banerjee, D.; Guin, R.; Das, S.K.; Thakare, S.V.

    2011-01-01

    A new method for the possible incorporation of nuclear wastes has been attempted here by using ceramic matrix of TiO 2 as a host precursor for confinement. Hafnium is used as a simulant for actinide high-level waste. After incorporating 181 Hf tracer into TiO 2 matrix, the leaching property of the resulting matrix was studied in water, sodium chloride and humic acid solutions. The leaching was measured in each of the case by following the radioactivity of 181 Hf. TiO 2 matrix has also been exposed to γ-radiation in order to simulate the radiation field for nuclear waste. It has been investigated with a nuclear technique called time differential perturbed Angular Correlation (TDPAC) that the lattice structure of titania remains undisturbed even under a strong radiation field. The leaching of 181 Hf has also been studied after irradiating the TiO 2 matrix with ?-radiation and the leaching behavior was observed not to change from that before irradiation. (author)

  7. Comparing LCZ696 with enalapril according to baseline risk using the MAGGIC and EMPHASIS-HF risk scores: an analysis of mortality and morbidity in PARADIGM-HF.

    Science.gov (United States)

    Simpson, Joanne; Jhund, Pardeep S; Silva Cardoso, Jose; Martinez, Felipe; Mosterd, Arend; Ramires, Felix; Rizkala, Adel R; Senni, Michele; Squire, Iain; Gong, Jianjian; Lefkowitz, Martin P; Shi, Victor C; Desai, Akshay S; Rouleau, Jean L; Swedberg, Karl; Zile, Michael R; McMurray, John J V; Packer, Milton; Solomon, Scott D

    2015-11-10

    Although most patients in the PARADIGM-HF (Prospective Comparison of ARNI With ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure) trial had mild symptoms, there is a poor correlation between reported functional limitation and prognosis in heart failure. The aim of this study was to examine the spectrum of risk in PARADIGM-HF and the effect of LCZ696 across that spectrum. This study analyzed rates of the primary composite outcome of cardiovascular death or heart failure hospitalization, its components, and all-cause mortality using the MAGGIC (Meta-Analysis Global Group in Chronic Heart Failure) and EMPHASIS-HF (Eplerenone in Mild Patients Hospitalization and Survival Study in Heart Failure) risk scores to categorize patients. The authors determined whether risk, on the basis of these scores, modified the treatment effect of LCZ696. The complete MAGGIC risk score was available for 8,375 of the 8,399 patients in PARADIGM-HF. The median MAGGIC score was 20 (IQR: 16 to 24). An increase of 1 point was associated with a 6% increased risk for the primary endpoint (p PARADIGM-HF patients had mild symptoms, many were at high risk for adverse outcomes and obtained a large absolute benefit from LCZ696, compared with enalapril, over a relatively short treatment period. LCZ696's benefit was consistent across the spectrum of risk. (PARADIGM-HF trial [Prospective Comparison of ARNI With ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure]; NCT01035255). Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  8. Formation of Al2O3-HfO2 Eutectic EBC Film on Silicon Carbide Substrate

    Directory of Open Access Journals (Sweden)

    Kyosuke Seya

    2015-01-01

    Full Text Available The formation mechanism of Al2O3-HfO2 eutectic structure, the preparation method, and the formation mechanism of the eutectic EBC layer on the silicon carbide substrate are summarized. Al2O3-HfO2 eutectic EBC film is prepared by optical zone melting method on the silicon carbide substrate. At high temperature, a small amount of silicon carbide decomposed into silicon and carbon. The components of Al2O3 and HfO2 in molten phase also react with the free carbon. The Al2O3 phase reacts with free carbon and vapor species of AlO phase is formed. The composition of the molten phase becomes HfO2 rich from the eutectic composition. HfO2 phase also reacts with the free carbon and HfC phase is formed on the silicon carbide substrate; then a high density intermediate layer is formed. The adhesion between the intermediate layer and the substrate is excellent by an anchor effect. When the solidification process finished before all of HfO2 phase is reduced to HfC phase, HfC-HfO2 functionally graded layer is formed on the silicon carbide substrate and the Al2O3-HfO2 eutectic structure grows from the top of the intermediate layer.

  9. LVAD patients' and surrogates' perspectives on SPIRIT-HF: An advance care planning discussion.

    Science.gov (United States)

    Metzger, Maureen; Song, Mi-Kyung; Devane-Johnson, Stephanie

    2016-01-01

    To describe LVAD patients' and surrogates' experiences with, and perspectives on SPIRIT-HF, an advance care planning (ACP) intervention. ACP is important for patients with LVAD, yet little is known about their experiences or those of their surrogates who have participated in ACP discussions. We used qualitative content analysis techniques to conduct a secondary analysis of 28 interviews with patients with LVAD (n = 14) and their surrogates (n = 14) who had participated in an RCT pilot study of SPIRIT-HF. Main themes from the data include: 1) sharing their HF stories was very beneficial; 2) participating in SPIRIT-HF led to greater peace of mind for patients and surrogates; 3) "one size does not fit all" when it comes to timing of ACP discussions. An understanding patient and surrogate perspectives may inform clinicians' approach to ACP discussions. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Reducing the stoichiometric excess of HF in the hydrofluorination of UO2

    International Nuclear Information System (INIS)

    Zhao Jun; Qiu Lufu; Zhong Xing; Xu Heqing

    1989-11-01

    In a fluidized bed, UO 2 obtained from the decomposition-reduction of AUC (Ammonium Uranyl Carbonate) was fed to absorb HF remaining in the exhaust gas of UF 4 production process. In the case of 60% conversion of UO 2 and the reaction temperature in the region of 300 deg C, HF remaining in the exhaust gas in absorbing fluidized bed was less than 7 ∼ 8% (w/w), i.e. apparent stoichiometric excess of HF had reduced to 0% more or less. Hence, with the high hydrofluorination reactivity of UO 2 obtained from the decomposition-reduction of AUC, it is possible to reduce evidently the stoichiometric excess of HF in the hydrofluorination process by two fluidized beds in series in which solids move against the gas flow

  11. Ionic exchange of Hf donor impurities in the wide-gap semiconductor Tm2O3

    International Nuclear Information System (INIS)

    Munoz, E.L.; Darriba, G.N.; Bibiloni, A.G.; Errico, L.A.; Renteria, M.

    2010-01-01

    The ionic exchange of Hf donor impurities in substitutional cationic sites of the cubic (bixbyite) phase of the wide-gap semiconductor Tm 2 O 3 was studied. The doping process was performed by ball-milling-assisted solid-state reaction of Tm 2 O 3 and neutron-activated m-HfO 2 . 181 Ta atoms, obtained by the β-decay of the 181 Hf-isotope, were used as probes in time-differential perturbed-angular-correlation (TDPAC) experiments carried out after each step of the doping process. The measured hyperfine interactions at 181 Ta sites enabled the electric-field gradient (EFG) characterization at representative Hf impurity sites of each step of the process. The efficiency and substitutional character of the exchange process is discussed and elucidated in the framework of an empirical EFG systematic established in isostructural rare-earth bixbyite sesquioxides.

  12. HF183/BFDrev and HumM2 qPCR data

    Data.gov (United States)

    U.S. Environmental Protection Agency — Concentration estimates for HF183/BFDrev and HumM2 qPCR genetic markers in raw sewage collected from 54 geographic locations across the United States. This dataset...

  13. Study of bulk Hafnium oxide (HfO2) under compression

    Science.gov (United States)

    Pathak, Santanu; Mandal, Guruprasad; Das, Parnika

    2018-04-01

    Hafnium oxide (HfO2) is a technologically important material. This material has K-value of 25 and band gap 5.8 eV. A k value of 25-30 is preferred for a gate dielectric [1]. As it shows good insulating and capacitive properties, HfO2 is being considered as a replacement to SiO2 in microelectronic devices as gate dielectrics. On the other hand because of toughening mechanism due to phase transformation induced by stress field observed in these oxides, HFO2 has been a material of investigations in various configurations for a very long time. However the controversies about phase transition of HfO2 under pressure still exists. High quality synchrotron radiation has been used to study the structural phase transition of HfO2 under pressure.

  14. Glass formation of the Fe-Hf system studied by thermodynamic calculation and ion beam mixing

    International Nuclear Information System (INIS)

    Wang, T.L.; Wang, W.C.; Li, J.H.; Liu, B.X.

    2010-01-01

    For the Fe-Hf system characterized by a negative heat of formation, the glass-forming range/ability (GFR/GFA) was studied by thermodynamic calculation based on Miedema's model and Alonso's method. It was found that amorphous phase could be formed in a composition range of 24-86 atom% Hf and that alloy with composition of Fe 58 Hf 42 has the best GFA in the system. Experimentally, ion beam mixing was carried out to synthesize amorphous alloys in the Fe-Hf system. It turned out that in the samples with overall compositions located in the calculated GFR, amorphous phases were indeed obtained, whereas no amorphous phase was obtained if the overall compositions were located outside of the predicted region favoring for amorphous alloy formation, showing a good agreement between the experimental results and the thermodynamic calculation.

  15. Conduction Mechanism and Improved Endurance in HfO2-Based RRAM with Nitridation Treatment

    Science.gov (United States)

    Yuan, Fang-Yuan; Deng, Ning; Shih, Chih-Cheng; Tseng, Yi-Ting; Chang, Ting-Chang; Chang, Kuan-Chang; Wang, Ming-Hui; Chen, Wen-Chung; Zheng, Hao-Xuan; Wu, Huaqiang; Qian, He; Sze, Simon M.

    2017-10-01

    A nitridation treatment technology with a urea/ammonia complex nitrogen source improved resistive switching property in HfO2-based resistive random access memory (RRAM). The nitridation treatment produced a high performance and reliable device which results in superior endurance (more than 109 cycles) and a self-compliance effect. Thus, the current conduction mechanism changed due to defect passivation by nitrogen atoms in the HfO2 thin film. At a high resistance state (HRS), it transferred to Schottky emission from Poole-Frenkel in HfO2-based RRAM. At low resistance state (LRS), the current conduction mechanism was space charge limited current (SCLC) after the nitridation treatment, which suggests that the nitrogen atoms form Hf-N-Ox vacancy clusters (Vo +) which limit electron movement through the switching layer.

  16. Luminescence and scintillation properties of Rb2HfCl6 crystals

    International Nuclear Information System (INIS)

    Saeki, Keiichiro; Wakai, Yuki; Fujimoto, Yutaka; Koshimizu, Masanori; Asai, Keisuke; Yanagida, Takayuki; Nakauchi, Daisuke

    2016-01-01

    We developed a scintillator based on a Rb 2 HfCl 6 crystal as a ternary halide crystal with intrinsic luminescence. In the photoluminescence spectra, two emission bands are observed at 383 and 434 nm. The 434 nm emission band for Rb 2 HfCl 6 may be attributed to [HfCl 6 ] 2- complex ion or [ZrCl 6 ] 2- impurity, since the Rb 2 HfCl 6 contained Zr as impurity at 0.62 mol %. The radioluminescence band is observed at 420 nm and can be attributed to the same origin as the photoluminescence band at 434 nm. The scintillation decay-time constants were 0.84 and 5.4 μs. The light yield was estimated to be 24,100 photons/MeV. (author)

  17. Finishing and Commissioning the New Arecibo HF Facility

    Science.gov (United States)

    Sulzer, M. P.; Gonzalez, S. A.

    2011-12-01

    The imminent completion of the major tasks in the construction of the New Arecibo HF facility means that we must verify that the components are working as intended. The antenna system and the transmitters must be separately commissioned before they can be connected together so that we an be sure it will provide 83 dbW at 8.175 MHz, and 80 dbW at 5.1 MHz. The antenna system will be ready for initial testing in September. It Illuminates the 305 meter dish using dipoles near the surface of the dish transmitting upward to a wire mesh sub-reflector. There are three crossed dipoles for each of the two frequencies. The dipoles are supported on towers mounted on concrete pads underneath the dish. Each dipole element is connected to a transmitter through a three inch coax line. The tower foundations are nearly complete, and the towers will be erected in early September, and we expect to have at least one crossed dipole in place for initial testing by the end of September. We will need to make some measurements on the antenna system to ensure that it meets our requirements. One requirement is to match the antenna impedance to the transmission line and the transmitter closely enough to meet the transmitter specifications, the closer, the better. We have additional requirements; for example, it is necessary for efficient use of the facility that the polarization be close to circular. In most experiments, we want O mode excitation. If we were to transmit linear only half the power would reach the reflection height. The symmetry of the system assures that most of the conditions for achieving accurate circular polarization are met, but one condition is not: that exciting the transmitters driving the orthogonal elements at 90 degrees assures 90 degree separation in the corresponding antenna currents. One of the dipoles of each pair points toward the center of the array. If we think of the three crossed dipoles as consisting of a reference and two that are excited relative to it

  18. Suppression of interfacial reaction for HfO2 on silicon by pre-CF4 plasma treatment

    International Nuclear Information System (INIS)

    Lai, C.S.; Wu, W.C.; Chao, T.S.; Chen, J.H.; Wang, J.C.; Tay, L.-L.; Rowell, Nelson

    2006-01-01

    In this letter, the effects of pre-CF 4 plasma treatment on Si for sputtered HfO 2 gate dielectrics are investigated. The significant fluorine was incorporated at the HfO 2 /Si substrate interface for a sample with the CF 4 plasma pretreatment. The Hf silicide was suppressed and Hf-F bonding was observed for the CF 4 plasma pretreated sample. Compared with the as-deposited sample, the effective oxide thickness was much reduced for the pre-CF 4 plasma treated sample due to the elimination of the interfacial layer between HfO 2 and Si substrate. These improved characteristics of the HfO 2 gate dielectrics can be explained in terms of the fluorine atoms blocking oxygen diffusion through the HfO 2 film into the Si substrate

  19. Effects of C and Hf concentration on phase relations and microstructure of a wrought powder-metallurgy superalloy

    Science.gov (United States)

    Miner, R. V., Jr.

    1977-01-01

    NASA IIB-11, a candidate alloy for advanced temperature turbine engine disks, and four modifications with varying C and Hf concentrations were produced from prealloyed powders. Several notable effects of C and Hf concentration in the alloys were observed. Both the amount of the gamma-prime phase and its solvus temperature increased with decreasing C, but only the gamma-prime solvus was affected by Hf, increasing with increasing Hf. Hf also promoted a cellular gamma-prime precipitation. Hf was, however, about equally distributed between gamma-prime and gamma. Hf and C both affected the carbides formed. Increasing both promoted formation of an MC relative to that of an M6C.

  20. The CaO-TiO2-ZrO2 system at 1,200 degree C and the solubilities of Hf and Gd in zirconolite

    International Nuclear Information System (INIS)

    Swenson, D.; Nieh, T.G.; Fournelle, J.H.

    1995-12-01

    In recent years, significant technological advancements have been made in the Synroc scheme for the immobilization high-level nuclear waste. However, many basic scientific issues related to Synroc fabrication have yet to be addressed. The CaO-TiO 2 -ZrO 2 system is an integral part of the Synroc formulation. Phase equilibria are established in the CaO-TiO 2 -ZrO 2 system at 1,200 C, using X-ray diffraction and electron probe microanalysis. The existence of two previously reported ternary phases, zirconolite (CaZrTi 2 O 7 ) and calzirtite (Ca 2 Zr 5 Ti 2 O 16 ), is confirmed. Each of these phases exhibits a significant range of homogeneity between TiO 2 and ZrO 2 while maintaining a nearly constant concentration of CaO. The ternary solubilities of the constituent binary phases are found to be negligible, with the exceptions of the perovskites, which display mutual solubility of at least 22 mol.% and may in fact form a series of continuous solid solutions. The solubilities of Hf and Gd in zirconolite are also investigated. While Hf-bearing samples did not reach thermodynamic equilibrium under the experimental conditions employed, the existence of a Hf analog to zirconolite, CaHfTi 2 O 7 , is conclusively demonstrated. The phase is stable at the stoichiometric composition, and its lattice parameters are very close to those reported in the literature for stoichiometric zirconolite. A Gd-bearing sample of the composition Ca 0.88 Zr 0.88 Gd 9.24 Ti 2 O 7 is found to be essentially single phase zirconolite, in agreement with previous investigations at higher temperatures

  1. High-Frequency Electron Paramagnetic Resonance Spectroscopy of Nitroxide-Functionalized Nanodiamonds in Aqueous Solution.

    Science.gov (United States)

    Akiel, R D; Stepanov, V; Takahashi, S

    2017-06-01

    Nanodiamond (ND) is an attractive class of nanomaterial for fluorescent labeling, magnetic sensing of biological molecules, and targeted drug delivery. Many of those applications require tethering of target biological molecules on the ND surface. Even though many approaches have been developed to attach macromolecules to the ND surface, it remains challenging to characterize dynamics of tethered molecule. Here, we show high-frequency electron paramagnetic resonance (HF EPR) spectroscopy of nitroxide-functionalized NDs. Nitroxide radical is a commonly used spin label to investigate dynamics of biological molecules. In the investigation, we developed a sample holder to overcome water absorption of HF microwave. Then, we demonstrated HF EPR spectroscopy of nitroxide-functionalized NDs in aqueous solution and showed clear spectral distinction of ND and nitroxide EPR signals. Moreover, through EPR spectral analysis, we investigate dynamics of nitroxide radicals on the ND surface. The demonstration sheds light on the use of HF EPR spectroscopy to investigate biological molecule-functionalized nanoparticles.

  2. Hydrogen fluoride (HF) substance flow analysis for safe and sustainable chemical industry.

    Science.gov (United States)

    Kim, Junbeum; Hwang, Yongwoo; Yoo, Mijin; Chen, Sha; Lee, Ik-Mo

    2017-11-01

    In this study, the chemical substance flow of hydrogen fluoride (hydrofluoric acid, HF) in domestic chemical industries in 2014 was analyzed in order to provide a basic material and information for the establishment of organized management system to ensure safety during HF applications. A total of 44,751 tons of HF was made by four domestic companies (in 2014); import amount was 95,984 tons in 2014 while 21,579 tons of HF was imported in 2005. The export amount of HF was 2180 tons, of which 2074 ton (China, 1422 tons, U.S. 524 tons, and Malaysia, 128 tons) was exported for the manufacturing of semiconductors. Based on the export and import amounts, it can be inferred that HF was used for manufacturing semiconductors. The industries applications of 161,123 tons of HF were as follows: manufacturing of basic inorganic chemical substance (27,937 tons), manufacturing of other chemical products such as detergents (28,208 tons), manufacturing of flat display (24,896 tons), and manufacturing of glass container package (22,002 tons). In this study, an analysis of the chemical substance flow showed that HF was mainly used in the semiconductor industry as well as glass container manufacturing. Combined with other risk management tools and approaches in the chemical industry, the chemical substance flow analysis (CSFA) can be a useful tool and method for assessment and management. The current CSFA results provide useful information for policy making in the chemical industry and national systems. Graphical abstract Hydrogen fluoride chemical substance flows in 2014 in South Korea.

  3. Mid-Latitude Mobile Wideband HF- NVIS Channel Analysis: Part 1

    Science.gov (United States)

    2017-09-14

    commercial satellite communications (SATCOM) for beyond line-of-sight (LOS) links. However, standard HF systems operating over a 3-kHz bandwidth do not...citation of trade names and names of names of manufacturers is not to be construed as official government endorsement or approval of commercial ...Division EXECUTIVE SUMMARY High frequency (HF) links (2 to 30 MHz) are an alternative to the cost and tactical fragility of commercial satellite

  4. Sr-Nd-Hf isotopic fingerprinting of transatlantic dust derived from North Africa

    Science.gov (United States)

    Zhao, Wancang; Balsam, William; Williams, Earle; Long, Xiaoyong; Ji, Junfeng

    2018-03-01

    Long-range transport of African dust plays an important role in understanding dust-climate relationships including dust source areas, dust pathways and associated atmospheric and/or oceanic processes. Clay-sized Sr-Nd-Hf isotopic compositions can be used as geochemical fingerprints to constrain dust provenance and the pathways of long-range transported mineral dust. We investigated the clay-sized Sr-Nd-Hf isotopic composition of surface samples along four transects bordering the Sahara Desert. The transects are from Mali, Niger/Benin/Togo, Egypt and Morocco. Our results show that the Mali transect on the West African Craton (WAC) produces lower εNd (εNd-mean = -16.38) and εHfHf-mean = -9.59) values than the other three transects. The Egyptian transect exhibits the lowest 87Sr/86Sr ratios (87Sr/86Srmean = 0.709842), the highest εHfHf-mean = -0.34) and εNd values of the four transects. Comparison of the clay-sized Sr-Nd-Hf isotopic values from our North African samples to transatlantic African dust collected in Barbados demonstrates that the dust's provenance is primarily the western Sahel and Sahara as well as the central Sahel. Summer emission dust is derived mainly from the western Sahel and Sahara regions. The source of transatlantic dust in spring and autumn is more varied than in the summer and includes dust not only from western areas, but also south central areas. Comparison of the Sr-Nd-Hf isotopic fingerprints between the source and sink of transatlantic dust also suggests that a northwestward shift in dust source occurs from the winter, through the spring and into the summer. The isotopic data we develop here provide another tool for discriminating changes in dust archives resulting from paleoenvironmental evolution of source regions.

  5. Results of gas exposure experiments for determination of HF concentrations injurious to plants

    Energy Technology Data Exchange (ETDEWEB)

    Guderian, R

    1971-01-01

    Gas exposure experiments were performed under greenhouse conditions to determine the effects of hydrogen fluoride on the growth capacity, yield and quality of plants. Damage to plants was assessed after HF concentrations of 0.85-25 ..mu..g/m/sup 3/. The effects of definite HF quantities on plants are described and relative sensitivities of 17 deciduous trees, 9 evergreens, 24 agricultural garden plants and 17 ornamental plants are presented. 2 references, 7 tables.

  6. Enhancement of organic light-emitting device performances with Hf-doped indium tin oxide anodes

    International Nuclear Information System (INIS)

    Chen, T.-H.; Liou, Y.; Wu, T.J.; Chen, J.Y.

    2004-01-01

    We have enhanced the luminance and the power efficiency of organic light-emitting devices with Hf-doped indium tin oxide (ITO) anodes instead of a CuPc layer. The Hf-doped ITO layer with a thickness of 15 nm was deposited on top of the ITO anode. Less than 10 mol. % of Hf was doped in ITO films by adjusting the sputtering rates of both sources. The highest work function of the Hf-doped ITO layers was 5.4 eV at the Hf concentrations about 10 mol. %. The driving voltages of the device have been reduced by 1 V. A luminance of 1000 cd/m 2 at 7 mA/cm 2 , a current efficiency of 14 cd/A, and a power efficiency of 6 lm/W at 6 mA/cm 2 have been achieved in the device with a 4 mol. % Hf-doped ITO layer (work function=5.2 eV). In general, the performance was about 50% better than the device with a CuPc buffer layer

  7. Comparison of HF radar measurements with Eulerian and Lagrangian surface currents

    Science.gov (United States)

    Röhrs, Johannes; Sperrevik, Ann Kristin; Christensen, Kai Håkon; Broström, Göran; Breivik, Øyvind

    2015-05-01

    High-frequency (HF) radar-derived ocean currents are compared with in situ measurements to conclude if the radar observations include effects of surface waves that are of second order in the wave amplitude. Eulerian current measurements from a high-resolution acoustic Doppler current profiler and Lagrangian measurements from surface drifters are used as references. Directional wave spectra are obtained from a combination of pressure sensor data and a wave model. Our analysis shows that the wave-induced Stokes drift is not included in the HF radar-derived currents, that is, HF radars measure the Eulerian current. A disputed nonlinear correction to the phase velocity of surface gravity waves, which may affect HF radar signals, has a magnitude of about half the Stokes drift at the surface. In our case, this contribution by nonlinear dispersion would be smaller than the accuracy of the HF radar currents, hence no conclusion can be made. Finally, the analysis confirms that the HF radar data represent an exponentially weighted vertical average where the decay scale is proportional to the wavelength of the transmitted signal.

  8. Ergonomics action research II: a framework for integrating HF into work system design.

    Science.gov (United States)

    Neumann, W P; Village, J

    2012-01-01

    This paper presents a conceptual framework that can support efforts to integrate human factors (HF) into the work system design process, where improved and cost-effective application of HF is possible. The framework advocates strategies of broad stakeholder participation, linking of performance and health goals, and process focussed change tools that can help practitioners engage in improvements to embed HF into a firm's work system design process. Recommended tools include business process mapping of the design process, implementing design criteria, using cognitive mapping to connect to managers' strategic goals, tactical use of training and adopting virtual HF (VHF) tools to support the integration effort. Consistent with organisational change research, the framework provides guidance but does not suggest a strict set of steps. This allows more adaptability for the practitioner who must navigate within a particular organisational context to secure support for embedding HF into the design process for improved operator wellbeing and system performance. There has been little scientific literature about how a practitioner might integrate HF into a company's work system design process. This paper proposes a framework for this effort by presenting a coherent conceptual framework, process tools, design tools and procedural advice that can be adapted for a target organisation.

  9. Probing the effect of neutron excess on the dynamics of Hf compound system

    Science.gov (United States)

    Sharma, Ishita; Kumar, Raj; Sharma, Manoj K.

    2018-05-01

    The reaction dynamics of 170Hf* and 174Hf* compound systems formed in 46,50Ti +124Sn reactions have been analyzed within the framework of Dynamical Cluster-decay Model (DCM) over an energy range of Ec.m.=115-156 MeV. The experimental data of fusion evaporation cross sections for 170,174Hf* systems is successfully addressed by optimizing the value of neck length ΔR. It is to be noted that calculations are performed by taking quadrupole deformations β2 with the optimum orientation of decaying fragments. Here, the effect of neutron excess has been examined on the structural properties of decaying fragments via fragmentation potential and preformation probability. The observation depicts that the isotopic effect prevails at fission region and as we move from lighter nucleus i.e. 170Hf* to heavier nucleus i.e. 174Hf*, the heavy mass fragments (HMF) start contributing along with fission fragments which are equally evident for 170Hf* as well. The ΔR values so obtained are compared at center of mass-energies which consequently provides information regarding the relative time scale of decaying fragments.

  10. Chemical reaction at the interface between pentacene and HfO2

    International Nuclear Information System (INIS)

    Kang, S.J.; Yi, Y.; Kim, K.H.; Yoo, C.Y.; Moewes, A.; Cho, M.H.; Denlinger, J.D.; Whang, C.N.; Chang, G.S.

    2005-01-01

    The electronic structure and the interface formation at the interface region between pentacene and HfO2 are investigated using x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and x-ray emission spectroscopy (XES). The measured C 1s XPS spectra of pentacene indicate that chemical bonding occurs at the interface between pentacene and HfO2. The carbon of pentacene reacts with oxygen belonging to HfO2 and band bending occurs at the interface due to a redistribution of charge. The determined interface dipole and band bending between pentacene and HfO2 are 0.04 and 0.1 eV, respectively. The highest occupied molecular orbital (HOMO) level is observed at 0.68 eV below the Fermi level. This chemical reaction allows us to grow a pentacene film with large grains onto HfO2. We conclude that high performance pentacene thin film transistors can be obtained by inserting an ultrathin HfO2 layer between pentacene and a gate insulator

  11. Oxidation Study of an Ultra High Temperature Ceramic Coatings Based on HfSiCN

    Science.gov (United States)

    Sacksteder, Dagny; Waters, Deborah L.; Zhu, Dongming

    2018-01-01

    High temperature fiber-reinforced ceramic matrix composites (CMCs) are important for aerospace applications because of their low density, high strength, and significantly higher-temperature capabilities compared to conventional metallic systems. The use of the SiCf/SiC and Cf/SiC CMCs allows the design of lighter-weight, more fuel efficient aircraft engines and also more advanced spacecraft airframe thermal protection systems. However, CMCs have to be protected with advanced environmental barrier coatings when they are incorporated into components for the harsh environments such as in aircraft engine or spacecraft applications. In this study, high temperature oxidation kinetics of an advanced HfSiCN coating on Cf/SiC CMC substrates were investigated at 1300 C, 1400 C, and 1500 C by using thermogravimetric analysis (TGA). The coating oxidation reaction parabolic rate constant and activation energy were estimated from the experimental results. The oxidation reaction studies showed that the coatings formed the most stable, predominant HfSiO4-HfO2 scales at 1400 C. A peroxidation test at 1400 C then followed by subsequent oxidation tests at various temperatures also showed more adherent scales and slower scale growth because of reduced the initial transient oxidation stage and increased HfSiO4-HfO2 content in the scales formed on the HfSiCN coatings.

  12. Regularities in electroconductivity and thermo-emf in systems of binary continuous solid solutions of metals

    International Nuclear Information System (INIS)

    Vedernikov, M.V.; Dvunitkin, V.G.; Zhumagulov, A.

    1978-01-01

    Given are new experimental data about specific electric resistance of 10 systems of binary continuous solid metal solutions at the temperatures of 293 and 4.2 K: Cr-V, Mo-Nb, Mo-V, Cr-Mo, Nb-V, Ti-Zr, Hf-Zr, Hf-Ti, Sc-Zr, Sc-Hf. For the first time a comparative analysis of all available data on the resistance dependence on the composition of systems of continuous solid solutions, which covers 21 systems, is carried out. The ''resistance-composition'' dependence for such alloy systems is found to be of two types. The dependence of the first type is characteristic of the systems, formed by two isoelectronic metals, the dependence of the second type - for the systems, formed by non-isoelectronic metals. Thermo-emf of each type of solid solutions differently depends on their compositions

  13. Separation of hafnium from zirconium in their tetrachloride solution in molten alkali metal chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Salyulev, A B; Kudyakov, V Ya; Smirnov, M V; Moskalenko, N I [AN SSSR, Sverdlovsk. Inst. Ehlektrokhimii

    1984-08-01

    The coefficient of HfCl/sub 4/ and ZrCl/sub 4/ separation in the process of vapour sublimation from their solutions in molten NaCl, KCl, CsCl, NaCl-KCl and NaCl-CsCl equimolar mixtures is found to vary in the series from approximately 1.10 to approximately 1.22 and practically not to depend on the temperature (in the 600-910 deg) range and concentration (2-25 mol.% ZrCl/sub 4/+HfCl/sub 4/). HfCl/sub 4/ and ZrCl/sub 4/ are shown to form almost perfect solutions with each other, which in their turn form imperfect solutions with molten alkali metal chlorides, with the strength of hafnium complex chloride anions increasing higher than that of zirconium in the series from NaCl to CsCl.

  14. Separation of hafnium from zirconium in their tetrachloride solution in molten alkali metal chlorides

    International Nuclear Information System (INIS)

    Salyulev, A.B.; Kudyakov, V.Ya.; Smirnov, M.V.; Moskalenko, N.I.

    1984-01-01

    The coefficient of HfCl 4 and ZrCl 4 separation in the process of vapour sublimation from their solutions in molten NaCl, KCl, CsCl, NaCl-KCl and NaCl-CsCl equimolar mixtures is found to vary in the series from approximately 1.10 to approximately 1.22 and practically not to depend on the temperature (in the 600-910 deg) range and concentration (2-25 mol.% ZrCl 4 +HfCl 4 ). HfCl 4 and ZrCl 4 are shown to form almost perfect solutions with each other, which in their turn form imperfect solutions with molten alkali metal chlorides, with the strength of hafnium complex chloride anions increasing higher than that of zirconium in the series from NaCl to CsCl

  15. Plugging solution

    Energy Technology Data Exchange (ETDEWEB)

    Sharipov, A U; Yangirov, I Z

    1982-01-01

    A clay-powder, cement, and water-base plugging solution is proposed having reduced solution viscosity characteristics while maintaining tensile strength in cement stone. This solution utilizes silver graphite and its ingredients, by mass weight, are as follows: cement 51.2-54.3%; claypowder 6.06-9.1%; silver graphite 0.24-0.33%; with water making up the remainder.

  16. Effect of pH on the optical and structural properties of HfO{sub 2}:Ln{sup 3+}, synthesized by hydrothermal route

    Energy Technology Data Exchange (ETDEWEB)

    Montes, E., E-mail: emontesr@live.com.mx [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada IPN, Legaría 694, 11500, D.F. (Mexico); Martínez-Merlín, I.; Guzmán-Olguín, J.C.; Guzmán-Mendoza, J. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada IPN, Legaría 694, 11500, D.F. (Mexico); Martín, I.R. [Depto. de Física Fundamental y Experimental, Electrónica y Sistemas, Univ. de La Laguna, Av. Astrofísico Francisco Sánchez s/n E-38206, La Laguna. Tenerife (Spain); García-Hipólito, M. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior, Cd. Universitaria, 04510, D.F. (Mexico); Falcony, C. [Departamento de Física, CINVESTAV IPN, Apartado Postal 14-740, 07000, D.F. (Mexico)

    2016-07-15

    In this work, the influence of the chlorine ions in the optical and structural properties of hafnium oxide (HfO{sub 2}) doped with europium (Eu{sup 3+}) and terbium (Tb{sup 3+}) are reported. The synthesis was conducted by hydrothermal route at a temperature of 200 °C, with a reaction time of 80 min and a concentration of 3 mol% of both dopants, in relation to hafnium in solution. In order to study the influence of acidity on the kinetics of reaction, the pH of the precursor solution was varied in the range of pH=4 to pH=12. X-ray powder diffraction patterns showed that the materials crystallized better under alkaline conditions with pH=11, noting a better crystallinity in the material doped with Eu{sup 3+}showed a better crystallinity that Tb{sup 3+} ions. The characteristic rhombohedral microstructure of HfO{sub 2} in the monoclinic phase was observed in alkaline media. Photoluminescent spectra showed the characteristic peaks of the emissions for both Eu an Tb dopants, where the intensity of the luminescent emission increases by decreasing the concentration of chlorine ions. On the other hand, it was found that radiative life kinetics of the dopant is related to the kinetics of crystallization, and therefore, to the acidity of the precursor solution.

  17. Dual HF radar study of the subauroral polarization stream

    Directory of Open Access Journals (Sweden)

    R. A. Makarevich

    2008-01-01

    Full Text Available The dual HF radars comprising the Tasman International Geophysical Environment Radar (TIGER system often observe localized high-velocity F-region plasma flows (≥1500 m/s in the midnight sector (20:00–02:00 MLT at magnetic latitudes as low as Λ=60° S. The flow channels exhibit large variability in the latitudinal extent and electric field strength, and are similar to the subauroral polarization stream or SAPS, a plasma convection feature thought to be related to the polarization electric field due to the charge separation during substorm and storm development. In this study, the 2-D plasma drift velocity within the channel is derived for each of the two TIGER radars from the maximum velocities measured in all 16 radar beams within the latitudinally narrow channel, and the time variation of the subauroral electric field is examined near substorm onset. It is demonstrated that the flow channel often does not have a clear onset, rather it manifests differently in different phases of its evolution and can persist for at least two substorm cycles. During the growth phase the electric fields within the flow channel are difficult to distinguish from those of the background auroral convection but they start to increase near substorm onset and peak during the recovery phase, in contrast to what has been reported previously for auroral convection which peaks just before the substorm onset and falls sharply at the substorm onset. The response times to substorm onset range from −5 to +40 min and show some dependence on the substorm location with longer delays observed for substorms eastward of the radars' viewing area. The propagation velocity of the high-velocity region is also investigated by comparing the observations from the two closely-spaced TIGER radars. The observations are consistent with the notion that the polarization electric field is established with the energetic ions drifting westward and equatorward from the initial substorm

  18. HfO2 as gate dielectric on Ge: Interfaces and deposition techniques

    International Nuclear Information System (INIS)

    Caymax, M.; Van Elshocht, S.; Houssa, M.; Delabie, A.; Conard, T.; Meuris, M.; Heyns, M.M.; Dimoulas, A.; Spiga, S.; Fanciulli, M.; Seo, J.W.; Goncharova, L.V.

    2006-01-01

    To fabricate MOS gate stacks on Ge, one can choose from a multitude of metal oxides as dielectric material which can be deposited by many chemical or physical vapor deposition techniques. As a few typical examples, we will discuss here the results from atomic layer deposition (ALD), metal organic CVD (MOCVD) and molecular beam deposition (MBD) using HfO 2 /Ge as materials model system. It appears that a completely interface layer free HfO 2 /Ge combination can be made in MBD, but this results in very bad capacitors. The same bad result we find if HfGe y (Hf germanides) are formed like in the case of MOCVD on HF-dipped Ge. A GeO x interfacial layer appears to be indispensable (if no other passivating materials are applied), but the composition of this interfacial layer (as determined by XPS, TOFSIMS and MEIS) is determining for the C/V quality. On the other hand, the presence of Ge in the HfO 2 layer is not the most important factor that can be responsible for poor C/V, although it can still induce bumps in C/V curves, especially in the form of germanates (Hf-O-Ge). We find that most of these interfacial GeO x layers are in fact sub-oxides, and that this could be (part of) the explanation for the high interfacial state densities. In conclusion, we find that the Ge surface preparation is determining for the gate stack quality, but it needs to be adapted to the specific deposition technique

  19. Lu{sub 2}O{sub 3}:Tb,Hf storage phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kulesza, Dagmara; Trojan-Piegza, Joanna [Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, 50-383 Wroclaw (Poland); Zych, Eugeniusz, E-mail: zych@wchuwr.p [Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, 50-383 Wroclaw (Poland)

    2010-03-15

    Lu{sub 2}O{sub 3}:Tb,Hf ceramics containing 0.1% of Tb and 0-1.5% of Hf were prepared in reducing atmosphere at 1700 {sup o}C and their thermoluminescence properties were systematically studied. For comparison Tb,Ca co-doped specimen was also fabricated and investigated. The Tb,Hf ceramics shows basically a single TL band located around 180 {sup o}C as found with heating rate of 15 {sup o}C/min. Ceramics singly doped with Tb show complex TL glow curves indicating the presence of traps of very different depths. On the other hand Tb,Ca co-doping is beneficial for the development of shallow traps with the main TL band around 70 {sup o}C. Hence, the aliovalent impurities, Ca{sup 2+} and Hf{sup 4+}, strongly influenced the traps structure in Lu{sub 2}O{sub 3}:Tb ceramics, each of them in its own specific way. Isothermal decay of Lu{sub 2}O{sub 3}:Tb,Hf at 185 {sup o}C was recorded and its shape suggest that multiple hole trapping occurs in the Lu{sub 2}O{sub 3}:Tb,Hf ceramics. Due to the different traps depths the Lu{sub 2}O{sub 3}:Tb,Hf ceramics possess properties typical for storage phosphors, while Lu{sub 2}O{sub 3}:Tb,Ca is a persistent luminescent material rather.

  20. Structural, morphological, optical and photoluminescence properties of HfO2 thin films

    International Nuclear Information System (INIS)

    Ma, C.Y.; Wang, W.J.; Wang, J.; Miao, C.Y.; Li, S.L.; Zhang, Q.Y.

    2013-01-01

    Nanocrystalline monoclinic HfO 2 films with an average crystal size of 4.2–14.8 nm were sputter deposited under controlled temperatures and their structural characteristics and optical and photoluminescence properties have been evaluated. Structural investigations indicate that monoclinic HfO 2 films grown at higher temperatures above 400 °C are highly oriented along the (− 111) direction. The lattice expansion increases with diminishing HfO 2 crystalline size below 6.8 nm while maximum lattice expansion occurs with highly oriented monoclinic HfO 2 of crystalline size about 14.8 nm. The analysis of atomic force microscopy shows that the film growth at 600 °C can be attributed to the surface-diffusion-dominated growth. The intensity of the shoulderlike band that initiates at ∼ 5.7 eV and saturates at 5.94 eV shows continued increase with increasing crystalline size, which is intrinsic to nanocrystalline monoclinic HfO 2 films. Optical band gap varies in the range 5.40 ± 0.03–5.60 ± 0.03 eV and is slightly decreased with the increase in crystalline size. The luminescence band at 4.0 eV of HfO 2 films grown at room temperature can be ascribed to the vibronic transition of excited OH · radical while the emission at 3.2–3.3 eV for the films grown at all temperatures was attributed to the radiative recombination at impurity and/or defect centers. - Highlights: • Nanocrystalline monoclinic HfO 2 films were sputter deposited. • Structural, optical and photoluminescence properties were studied. • To analyze the scaling behavior using the power spectral density • Optical and photoluminescence properties strongly depend on film growth temperature