Interstitial Nitrogen Atoms Research Articles

Effects of nitrogen on dislocation behavior and mechanical strength in silicon crystals

The characteristics of dislocation behavior and mechanical strength in tensile tests are investigated on the silicon crystals that are doped with nitrogen at the time of crystal growth by the floating-zone technique. These are compared with those in the usual floating-zone-grown silicon crystals. Nitrogen atoms dispersed in a silicon crystal are shown to have no influence on the velocities of dislocations in motion in the temperature range above 600 °C. Dislocations in the nitrogen-doped crystal are, however, immobilized while the crystal is kept under a low or zero applied stress at elevated temperatures. Like Czochralski-grown silicon, nitrogen-doped silicon shows a much higher yield strength than usual floating-zone-grown silicon when crystals are dislocated. It is concluded that interstitial nitrogen atoms bring about the hardening of silicon crystals through locking of dislocations upon congregating on the latter.

ChemInform Abstract: RHODIUM CARBONYL CLUSTERS WITH INTERSTITIAL NITROGEN ATOMS. PART 1. CRYSTAL AND MOLECULAR STRUCTURE OF THE BIS(TRIPHENYLPHOSPHINE)IMINIUM SALT OF THE ANION ENNEA‐μ‐CARBONYLHEXACARBONYL‐μ6‐NITRIDO‐POLYHEDRO‐HEXARHODATE(1‐)

Chemischer InformationsdienstVolume 14, Issue 19 Physical Organic Chemistry ChemInform Abstract: RHODIUM CARBONYL CLUSTERS WITH INTERSTITIAL NITROGEN ATOMS. PART 1. CRYSTAL AND MOLECULAR STRUCTURE OF THE BIS(TRIPHENYLPHOSPHINE)IMINIUM SALT OF THE ANION ENNEA-μ-CARBONYLHEXACARBONYL-μ6-NITRIDO-POLYHEDRO-HEXARHODATE(1-) R. BONFICHI, R. BONFICHISearch for more papers by this authorG. CIANI, G. CIANISearch for more papers by this authorA. SIRONI, A. SIRONISearch for more papers by this authorS. MARTINENGO, S. MARTINENGOSearch for more papers by this author R. BONFICHI, R. BONFICHISearch for more papers by this authorG. CIANI, G. CIANISearch for more papers by this authorA. SIRONI, A. SIRONISearch for more papers by this authorS. MARTINENGO, S. MARTINENGOSearch for more papers by this author First published: May 10, 1983 https://doi.org/10.1002/chin.198319080AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue19May 10, 1983 RelatedInformation

Origin of negative temperature coefficient of resistivity in polycrystalline Ti-N films

A negative temperature coefficient of electrical resistivity (TCR) has been observed in Ti-N films prepared by reactive evaporation or sputtering. Some samples measured had a resistivity minimum and the minimum temperature changing with varying nitrogen contents. To study the origin of this anomalous temperature dependence of resistivity, the crystallographic structures of Ti-N films were measured by x-ray diffraction. The resistivity data could be analyzed in terms of the existing theory based on the structural Kondo effect. The results demonstrated that the negative TCR originated from higher concentration of interstitial nitrogen atoms in the Ti-Nx solid-solution phase, and nitrogen vacancies and/or intrinsic stacking faults in the fcc TiNx compounds.

Synthesis and x-ray characterization of the [M6N(.mu.-CO)9(CO)6]-(M = cobalt, rhodium) anions. A new class of metal carbonyl cluster compounds containing an interstitial nitrogen atom

Synthesis and x-ray characterization of the [M6N(.mu.-CO)9(CO)6]-(M = cobalt, rhodium) anions. A new class of metal carbonyl cluster compounds containing an interstitial nitrogen atom

Effect of electron-irradiation on precipitation in Fe-N alloy

Abstract Nitride precipitates were not observed in the electron-irradiated Fe-0.013 wt.% N alloy during heating at Fe16N2 precipitation temperatures, but nitride precipitates were done in the unirradiated specimen area. It is then considered that interstitial nitrogen atoms N are trapped by atom vacancies V. and they form V-N pairs, thus nitrides cannot precipitate in the matrix for the lack of interstitial nitrogen atoms.

高純度３０Ｃｒ‐２Ｍｏ鋼の溶接部のぜい化―高純度フェライト系ステンレス鋼の溶接や金現象に関する研究 Ｉ

The factors which influence the toughness in the weld metal of high purity 30Cr-2Mo steel were investigated. On the basis of the results, the mechanism of the deterioration in the toughness of the weld metal was discussed. The results obtained in this study are as follows:(1) The remarkable deterioration in the toughness is occurral in the TIG weld metal when the shielding for the welds is insufficient.(2) Grain size and 475°C embrittlement do not significantly influence the toughness of the weld metal in as-welded condition.(3) The main cause of the deterioration in the toughness of the weld metal is picking-up of nitrogen during welding.(4) When picking-up of nitrogen is slight and nitrogen in the weld metal is less than about 100 ppm, no nitride precipitates. In this case, interstitial nitrogen atoms cause the embrittlement due to forming Cottrell atomosphere or distorting the lattice. However, when picking-up of nitrogen is heavier and the content of nitrogen in the weld metal grows up more than about 100 ppm, disc-like Cr2N precipitates on (100) plane in the matrix. Consequently, in addition to the cause mentioned above, the precipitation hardening by Cr2N and the lowering the energy for the cleavage fracture due to the fact that disc-like Cr2N precipitates on (100) plane cause the embrittlement of the weld metal.

Diffusion of hydrogen in niobium in the presence of trapping impurities studied by neutron spectroscopy

The diffusion of hydrogen in niobium with interstitial impurities was investigated by highresolution neutron spectroscopy for the system $\mathrm{Nb}{\mathrm{N}}_{x}{\mathrm{H}}_{y}$ with $x=0.4 \mathrm{and} 0.7$ at.% and $y=0.4 \mathrm{and} 0.3$ at.%, respectively. The neutron spectrum at larger scattering vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{Q}}$ consists of two parts: a narrow line centered at energy transfer $\ensuremath{\hbar}\ensuremath{\omega}=0$ (width 0.1-3 \ensuremath{\mu}eV) which is caused which is caused by hydrogen trapped on nitrogen atoms, and a broad component in the spectrum from hydrogen atoms which diffuse in the more or less undisturbed regions of the lattice. At small $\stackrel{\ensuremath{\rightarrow}}{\mathrm{Q}}$, the spectral width is directly related to the self-diffusion constant. The experimental spectra, measured as a function of temperature and scattering vector, were interpreted by two theoretical models: (i) a two-state random-walk model (RWM) where the hydrogen alternates between a trapped state and a state of undisturbed diffusion. The RWM is characterized by the mean escape rate from the trap $\frac{1}{{\ensuremath{\tau}}_{0}}$, and the capture rate on the traps $\frac{1}{{\ensuremath{\tau}}_{1}}$; and (ii) an elastic-continuum model: the nitrogen-hydrogen interaction is treated in terms of the elastic strain field produced by the interstitial nitrogen and hydrogen atoms, and in terms of a short-range hard-core repulsion. This model uses the elastic parameters of the niobium and the interstitial nitrogen and hydrogen atoms. The hard-core radius ${r}_{0}$ is the only disposable parameter of the model. The RWM should hold as long as $\frac{2\ensuremath{\pi}}{\stackrel{\ensuremath{\rightarrow}}{\mathrm{Q}}}$ is larger than the linear dimensions of the trapping region. Model (i) yields a very good and consistent description of the measured spectra as a function of the concentration $x$, the temperature and the scattering vector. The resulting parameters ${\ensuremath{\tau}}_{0}$ and ${\ensuremath{\tau}}_{1}$ have the predicted behavior. In particular, ${\ensuremath{\tau}}_{0}$ is independent of $x$, and ${\ensuremath{\tau}}_{1}^{\ensuremath{-}1}$ is proportional to $\mathrm{xD}(T)$ where $D$ is the self-diffusion constant in pure niobium. The trapping times are about two orders of magnitude larger than the mean rest time in pure niobium. Using a hard-core radius of ${r}_{0}\ensuremath{\simeq}2.3$ \AA{}, model (ii) describes very well the experimental spectra at small and large $\stackrel{\ensuremath{\rightarrow}}{\mathrm{Q}}$ values.

Optical studies of the 1.945 eV vibronic band in diamond

The 1.945eV band is the dominant end product of annealing radiation damage in diamonds containing isolated substitutional nitrogen atoms. In this paper uniaxial stress experiments are described which show the band to be a transition between A 1 (ground) and E (excited) electronic states of a trigonal centre, the E state being coupled predominantly to A 1 modes of vibration. Annealing experiments suggest that the centre is either a substitutional nitrogen atom plus an interstitial nitrogen atom, or a substitutional nitrogen atom plus a vacancy. Small differences between the luminescence and absorption bands are shown to be consistent with the double minima vibrational potential of the nitrogenvacancy model.

Snoek Rearrangement and Long-Range Diffusion during Strain-Ageing in Iron

AbstractThe strain-ageing kinetics of annealed (870°C/1143 K) and quenched (700°C/973 K) single crystals and quenched (700°C/973 K) polycrystalline specimens of Ferrovac-E iron were studied over the temperature range −10°C (263 K) to 70°C (343 K) employing the yield-point return technique. Snoek rearrangement of interstitials about dislocations was deduced from the results as the first stage of the strain-ageing process. The completion time required for Snoek rearrangement corresponds to the time required for a single jump of an interstitial carbon or nitrogen atom. The ageing process obeys a t2/3 relationship. Only minute amounts of interstitials are required: no drastic difference could therefore be observed between quenched and annealed specimens. The activation energy is in the range 14·1±2·3 to 14·9±0·5 kcal/mol (59·0±9·6 to 62·4± 2·1 kJ/mol). The first value is based on Arrhenius' equation, the second on Hartley's analysis using 45 separate experimental determinations. The second state of strain-age...

Mössbauer Effect in Iron-Nitrogen Alloys and Compounds

Mossbauer effects of 57 Fe in iron-nitrogen martensite and its tempering stages were measured. The spectra were resolved into the components corresponding to the 1st, 2nd, 3rd, 4th and farther n n Fe for each interstitial nitrogen atom. The analysis showed the localized perturbations by the nitrogen atoms on a host iron lattice similar to the case of iron-carbon martensite. 2) The principal axis of electric field gradient at the 2nd n n Fe in the α''-Fe 16 N 2 were determined to be directed to the nitrogen atom, not being parallel to the c -axis. The number of s and d electrons for the 1st n n Fe in some iron-nitrogen compounds were determined. The reduction of internal field, larger for interstitial alloys and compounds relative to substitutional ones, was proportional to the coordination number, n , to the neighboring nonmetal atoms. While, the variation of isomer shift depended upon both n and nonmetal concentration c .

The symmetry properties of the ND1 absorption centre in electron- irradiated diamond

The ND1 centre is produced in natural and synthetic diamond by primary radiation damage, but only occurs in strength when substantial concentrations of nitrogen are present in the lattice. The optical absorption associated with this centre consists of a sharp no-phonon line at 3.149 ev (80 degrees K) and phonon-assisted structure at higher energies centred at about 3.4 ev. Uniaxial stress measurements on the no-phonon line have been interpreted in terms of an A to T transition at a centre of Td symmetry, and from this and other evidence of the ND1 centre has been tentatively identified with an interstitial nitrogen atom.

The Correlation of Radiation-Hardening with Interstitial Nitrogen Content in Mild Steels

The interstitial nitrogen contents of annealed En2, silicon-killed, and aluminium-grain-size-controlled high-manganese mild steels have been determined quantitatively by internal-friction and chemical methods and qualitatively by strain-ageing. Comparison of the results with previously published data on the effects of neutron irradiation on the room-temperature tensile lower yield stresses of the steels shows that the magnitude of the radiation-hardening increased with increasing interstitial nitrogen content. The interstitial nitrogen and the radiation-hardening in the annealed silicon-killed mild steel were decreased by ageing at 650° C (923 K) before irradiation, presumably as a result of the nitrogen in solution combining with the silicon, forming silicon nitride or silicon–manganese nitride. The strain-ageing in the annealed and annealed and aged silicon-killed mild steel was reduced after irradiation, indicating that the interstitial nitrogen was removed from solution. It is tentatively concluded that the interstitial nitrogen atoms were trapped by the point defects or defect clusters introduced during irradiation and that the radiation-hardening was enhanced as a consequence of the effects of the nitrogen trapping on the size, density, and/or intrinsic strength of the defect clusters.

Diffusion and solubility of nitrogen in silicon-iron

Internal friction methods have been applied to a ternary alloy of iron, silicon and nitrogen. Two relaxation peaks have been resolved; the existence of a third is somewhat doubtful. The peaks corresponding to jumps of the interstitial nitrogen atoms are connected with sites either 1. (a) identical with those in pure alpha-iron, or 2. (b) in octahedra containing one silicon atom along the tetrad axis. The activation energies for these mechanisms are 18±1 and 12±2 kcal/mole, respectively. Bulk diffusion must take place through the former type of site. The majority of the nitrogen atoms sit in the silicon sites, at least for the temperature range of the present investigation, 250–1000°C. The solubility of nitrogen in a 3 per cent silicon-alloy has been determined within this temperature range and has been shown to be about an order of magnitude less than for pure alpha-iron. This solubility has been measured for equilibrium with a precipitated nitride. The heat of solution of this nitride is about 8 kcal/g-atom of nitrogen.