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Zinc Oxide (ZnO)
Published in Zbigniew Galazka, Transparent Semiconducting Oxides, 2020
The undoped and as-grown ZnO single crystals obtained by the Bridgman method contained the following residual impurities as indicated by SIMS [244] (in at. cm−3): Na ≈ 1017–1018; K, Mg, Ca ≈ 1016–1018; Cu ≈ 1018; Al and F ≈ 1017–1019; Si ≈ 1018–1019; Cl ≈ 1019– 1020 at. cm−3. EPR analysis also revealed traces of such impurities as Co, Mn, Li, and Na. ICP-OES results showed the following solid residual impurities [242] (in at. cm−3): Cr, Co, Ni, Ga, Zr, Ag, Te, and Pb ≈ 1015–1016 at. cm−3, and Al ≈ 1017 at. cm−3 (in some of the measured samples). When using nuclear reaction analysis (NRA), also bound hydrogen at the concentration of about mid 1016 at. cm−3 was found [242]. Moreover, the same elements, such as Cu and Al, were indicated at different concentrations when using SIMS and ICP-OES methods. This is due to the different accuracies of both methods and different samples used for both analyses, as there are many sources of the residual impurities, namely, a powdered ZnO starting material (purity between 4N and 6N), Ir crucible (purity typically 3N), alumina and zirconia thermal insulation and growth atmosphere (usually 5N). As the materials used in crystal growth experiments vary between runs or between groups of runs, different crystals may have different levels of residual impurities.
The Nature of S Phase Coatings and their Wear and Corrosion-Wear Behaviour when Applied to 316L
Published in Tom Bell, Katsuya Akamatsu, Stainless Steel 2000, 2020
P.A. Dearnley, K.L. Dahm, G. Aldrich-Smith
Coatings in the Fe–18Cr–12Ni–N system were obtained by reactive unbalanced magnetron sputtering from an AISI 316L target using a direct current Ar–N2 glow discharge plasma. Several coatings with nitrogen concentrations, [N], ranging from 0.3 to 80 N/100Me were obtained by varying the partial pressure of nitrogen (pN2) during reactive sputtering (Table 1). Most coatings were prepared using a laboratory facility6 but one S phase coating containing 32 N/100Me (24 at.% N) was produced by a UK-based coating vendor. For interstitial alloying, the number of nitrogen atoms per 100 metal atoms (N/100 Me) is a more meaningful parameter than the more usual atomic or weight per cent. Nuclear reaction analysis (NRA) was used to determine the concentration-depth profiles using the 14 N(d.αl) reaction as fully described elsewhere.7 A 1400 keV deuterium beam was used and quantification was obtained by collecting calibration spectra from TiN powder and thin film Si3N4 standards.
Characterization Methods
Published in Mark A. Prelas, Galina Popovici, Louis K. Bigelow, Handbook of Industrial Diamonds and Diamond Films, 2018
Karen McNamara Rutledge, Karen K. Gleason
Since ERS detects atoms lighter than the incident helium ions, it has been primarily used to study 1H or 2H in diamond films [Ingram 1992 and 1993]. Hydrogen concentrations of over 1.0 at. % have been measured by this technique, in disagreement with techniques such as NMR (see section 3.2.3) and IR spectroscopy (see section 2.2.2) which give lower hydrogen concentrations by about an order of magnitude. This may be due, in part, to the uncertainty of absolute concentrations or background hydrogen levels in the ERS method. Another factor is a thin (~10 nm) layer of hydrocarbon contamination on the surfaces of CVD diamond films. This contamination has been imaged with TEM, and the ERS measured hydrogen content was 10 at.% [Engel 1994]. Cleaning, for instance with an isopropanol rinse, can remove the contaminate layer, and is required for accurate results. Cleaning is also important for other techniques to measure hydrogen, such as nuclear reaction analysis (see section 8.4). Depth profiling was used to study the effects of annealing on both oxygen (RBS) and hydrogen (ERS) concentrations within the films, and showed that although surface impurities could be removed by annealing, concentrations in the bulk remained unaffected by the process [Ingram 1992]. ERS has also been used to study the mechanisms of proton and deuterium incorporation into CVD diamond [Ingram 1993].
Implication of nuclear analytical techniques for the assessment of coal quality in terms of ash content
Published in International Journal of Coal Preparation and Utilization, 2023
S. K. Samanta, V. Sharma, A. Sengupta, R. Acharya
Nuclear analytical techniques (NATs) attract many analytical chemists for being nondestructive, isotope specific, without spectral interference, without reagent blank correction and negligible matrix effect (Samanta et al. 2021). NAA (Sharma et al. 2019), PGNAA (Raja, Acharya, and Pujari 2020), Charge Particle Activation Analysis (CPAA) (Ishii, Valladon, and Debrun 1978; Strijckmans and Vandecasteele 1987), Particle Induced Gamma-ray Emission (PIGE) (Samanta et al. 2020) and Nuclear Reaction Analysis (NRA) (Earwaker 1994; Gavrilov, Krivchitch, and Lebedev 2003) are the common nuclear analytical techniques. Previously, NAA has been used for chemical characterization of coal and coal ash (Ogugbuaja and James 1995). Particle Induced X-ray Emission (PIXE) and Energy Dispersive X-ray Fluorescence (EDXRF) spectroscopy are the common X-ray-based radio-analytical techniques. A combination of PIGE and PIXE has also been utilized for the chemical characterization of Indian coals (Singh et al. 2020).
Thermogravimetric Oxidation Analyses of Carbon Tokamak Codeposits and Flakes
Published in Fusion Science and Technology, 2021
U. Shahid, B. W. N. Fitzpatrick, C. P. Chrobak, J. W. Davis, M. H. A. Piro
A study by Davis et al.5 conducted two thermo-oxidation experiments in the DIII-D tokamak operated by General Atomics in San Diego, California. Internal specimens of the tokamak, including specimens inserted into the torus, were exposed to a gaseous mixture of 20% O2/80% He at a pressure of 9.5 Torr and at a temperature in the range of 350°C to 360°C for a period of 2 h. The experiments utilized Fourier transform infrared spectroscopy and residual gas analysis (RGA) diagnostics to monitor the evolution of gases throughout the experiments. The experiments returned promising results. Deuterium, one of the hydrogen isotopes that attaches to the redeposited carbon, showed a 50% reduction from tile surfaces, as detected by nuclear reaction analysis6 (NRA). The gas evolution trends showed a decaying rate of O2 consumption along with an increase in partial pressures of expected thermo-oxidation products, including CO, CO2, and D2O (Ref. 5). The study also confirmed that the thermo-oxidation process had no adverse effects on tokamak components. The experiments further confirmed that the recovery of plasma performance was acceptable following the normal procedures for an open vent of the vacuum vessel. Similar experiments have been performed in the TEXTOR (Ref. 7) and HT-7 (Ref. 8) tokamaks; however, quantitative measurements of carbon removal or hydrogen isotope release could not be made as the oxygen partial pressure was too low.7,8
Experimental Study of Thick Target Yield from the 13C(α,n0)16O Reaction
Published in Nuclear Science and Engineering, 2023
P. S. Prusachenko, T. L. Bobrovskiy, M. V. Bokhovko, A. F. Gurbich
where the ρ13C = concentration of 13C atoms; ρO, ρH, ρSi, ρFe = concentrations of the atoms of oxygen, hydrogen, silicon, and iron determined from the analysis of the backscattered alpha-particle spectrum; 0.965 = coefficient taking into account the enrichment of the graphite target in 13C determined from the analysis of the products of the deuteron-induced reactions. Thus, the concentration of the carbon atoms in the target was determined taking into account the concentrations of all impurities, and the concentration of the 13C atoms was found using the carbon enrichment obtained from the nuclear reaction analysis described above.