Atomic parameter model for the solid solubilities in binary transition metal based alloys

Based on the same method by us which describes the solid solubilities of the binary nontransition metal based alloys, the solid solubilities at room temperature in 1380 binary alloys which are based on the 23 transition metals (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Mo, Ru, Rh, Pd, La, Hf, Ta, W, Re, Os, Ir and Pt) of the fourth, fifth and sixth long periods have been studied in this paper. It has been found that the soluble elements can be separated from the insoluble elements by an ellipse equation (x−m) ²/c ²+(y−n) ²/d ² = 1, by using a criterion of 0.5at% solubility at room temperature for every host element. The results show that the overall reliability for the ellipse equation is up to 90% for the 1380 alloys, which indicates the theoretical results are very good in agreement with the experimental data. The parameters m, n, c and d in the ellipse equation can be explained by the appropriate parameters for every host metal.     

Quadrupole moment of the doubly closed shell +1 nucleon nucleus41Sc(Iπ=7/2−)

The nuclear electric quadrupole moment of⁴¹Sc(I^π=7/2⁻) was experimentally determined by use of the NMR detection in which the asymmetric β-ray distribution from spin polarized nuclei was monitored. The magnetic interaction of the state with high external magnetic field and the nuclear quadrupole interaction with the electric field gradient obtained in TiO₂ crystal were studied. The field gradient seen to the implanted⁴¹Sc was measured independently by the high field NMR detection on the stable isotope⁴⁵Sc located in the equivalent⁴¹Sc site with. |Q(⁴¹Sc;I^π=7/2⁻)|=(0.120±0.006) b was determined.     

Indium solubility in iron studied with perturbed angular correlations

Segregation of In in Fe-based alloys containing 0.11–2.12 at.% In has been studied by measuring the perturbed angular correlations of γ-rays emitted in the nuclear decay of ¹¹¹In. The probe atoms were introduced into the alloys by either adding the carrier-free ¹¹¹In during melting or via ion implantation. Ageing of the samples at elevated temperatures followed by a slow cooling to room temperature allowed us to determine the upper limit of the solubility at room temperature, S(300 K)≤ 30 at. ppm. This value is far below the one reported in the published phase diagram. Quenching of the samples in water from 973–1373 K resulted in the determination of the indium solubility in iron at these elevated temperatures. This revised version was published online in August 2006 with corrections to the Cover Date.     

In-beam Mössbauer spectroscopy on isomer shift and diffusion of interstitial Fe

In-beam Mössbauer spectroscopy (IBMS) is used to study single isolated⁵⁷Fe impurities after implantation in metals and semiconductors with very restricted or even vanishing solubility for Fe. From the Mössbauer parameters it can be inferred that the Fe implants take up substitutional as well as interstitial sites. The strongly increased electron density at the interstitial position in metals is qualitatively explained by the pressure resulting from the small interstitial volume. In Si, Sc and Pb exponential line broadening due to interstitial diffusion has been observed. Additional information on the dynamic behavior and local magnetic structure in some of the systems presented comes from perturbed angular distribution experiments (PAD) performed on an isomeric state of⁵⁴Fe.     

A Possible Nuclear Spin Dewar. Hyperfine Interactions of Short-Lived β Emitter 8Li and 12B in TiO2

It was confirmed by detecting the β-NMR of ¹²B (I ^π=1⁺, T _1/2=20.2 ms) in a TiO₂ (rutile) crystal that the nuclear spin polarization of ¹²B was totally maintained in the crystal as produced through a nuclear reaction before implantation. Two locations, site 1 and site 2, were found with the relative populations 9 and 1, respectively, and the electric field gradients (EFGs) at those sites were obtained to be q(site 1)=+(37.1±0.5)10¹⁵ V/cm², η(site 1)<0.03, q(site 2)=+(185±5)10¹⁵ V/cm² and η(site 2)=0.62±0.02. We also found that about 30% of the initial polarization of ⁸Li (I ^π=2⁺, T _1/2=838 ms) was maintained in the crystal. Since the polarizations of other β emitting nuclei, ^12,16N, ^13,19O, and ⁴¹Sc were also totally maintained in the crystal, the crystal can be a “Spin Dewar” in which many short-lived nuclides can be implanted with their polarizations totally maintained during their lifetimes for the studies not only on the electronic structure of impurities in it but also on the nuclear properties. This revised version was published online in September 2006 with corrections to the Cover Date.     

Magic numbers and low energy nuclear transmutation by protons in host metals

The observed nuclear transmutations by protons or deuterons in host metals at low reaction energies are evaluated. Reaction probabilitiesN(Z) depending on the atomic numberZ show maxima close to the magic numbers with the exception ofZ=20. The exponential decay of the maxima onZ have an incrementZ′=10. Exactly this empirically derived relation fits a sequence of the magic numbers of 3 ⁿ , where the basis value 3 reminds of the threefold scheme of the quarks. Dedicated to Prof. Dr. D. Sc. Drs. h.c. Arthur Sharmann to his 70th birthday, 26 January 1998.     

Precise Quadrupole Moment of the Doubly Closed Shell Plus One Proton Nucleus 41Sc

In order to precisely determine the |eqQ(⁴¹Sc)/h| of ⁴¹Sc(I ^π=7/2⁻, T _1/2=0.596 s) implanted in a TiO₂ single crystal the electric field gradient tensor and anisotropic chemical shift were determined by detecting the Fourier Transformed Pulse-NMR of ⁴⁵Sc(I ^π=7/2⁻, stable) in the crystal at a high field of 7.0 T and 9.4 T. Combining the new |eqQ(⁴¹Sc)/h| value with the Q(⁴⁵Sc)=−(23.6±0.2) fm², also renewed by using the known atomic hyperfine interaction constants and Sternheimer polarization effect, the |Q(⁴¹Sc;I ^π=7/2⁻,T _1/2=0.596 s)|=(15.6±0.3) fm² has been precisely determined. The value is compared with the theoretical Q(⁴¹Sc) given by a shell model code. This revised version was published online in September 2006 with corrections to the Cover Date.     

Annealing behaviour of ion-implanted nickel-aluminium alloy

The time evolution of the aluminium concentration profiles in ion-implanted nickel-aluminium alloys during annealing has been studied in the temperature range 550–800°C using the (p, γ) resonance broadening method. The surface enrichment of aluminium has been found to be balanced by a corresponding uniform decrease in the bulk concentration and hence the bulk concentration profiles can be described by the modified solution of the second diffusion equation, when the implanted concentration does not exceed the solubility limit. When the solubility limit is exceeded the time evolution follows the solubility controlled flow of the solutes. The dependence of the degree of surface enrichment on the extra irradiation of⁵⁸Ni⁺ before and after the aluminium implantation is demonstrated and is found to be significant only in the post-irradiation cases. This is taken as evidence of the importance of interstitials in the development of the bulk concentration profiles. The linear Arrhenius plot extracted from the measurements indicates that the diffusion of A 1 in Ni can be described by the activation energyE=2.69 eV and the pre-exponential factorD ₀=0.6 cm²/s. Solid solubilities of aluminium in nickel from the implanted distribution are found to agree with those obtained using conventional metallographical methods.     

Cross relaxation studied by β NMR

The dipole-dipole interaction between polarized β active probes implanted into a metal and the surrounding host nuclei may lead to a transfer of polarization from the probe to the host. As energy must be conserved in this cross-relaxation (CR) process, resonance-like dips show up at certainB values, if the polarization of the probes is measured as a function of magnetic inductionB. The probe isotope¹²B has been studied in several metallic stoppers. For¹²B in the fec crystals Al, Cu the three possible cubic implantation sites could easily be discriminated by means of the CR technique. The temperature dependence of the dips yielded information on the diffusion of the probes. In the case of¹²B, in Cu above 400 K a further CR structure was found due to trapping of the probe at another site. In the bcc metal VCR spectra belonging to two different¹²B trapping sites could be separately registered using a special radiofrequency technique. Both, static and dynamical properties of the CR could be quantitatively explained by theory.     

Hydrogen incorporation behaviour and radiation damage in proton bombarded InP single crystals

Abstract

In proton bombarded InP single crystals the incorporation behaviour of different hydrogen isotopes is studied in relation to implantation induced radiation defects. Investigations of the fluence dependence (D = 10¹⁶-10¹⁸ cm^?2), of the depth profile and of the annealing behaviour (T _an = 300–1000 K) of hydrogen incorporation and of damage density indicate that only a small fraction of the implanted hydrogen is chemically bonded to host lattice atoms. These bonded hydrogen atoms saturate dangling bonds at defect sites.     

Theg-factor of the 9/2+ [624] ground state of183Os

The hyperfine interaction of¹⁸³OsFe has been studied with nuclear magnetic resonance on oriented nuclei after recoil implantation. Taking into account the resonance displacement due to quadrupole interaction |gμ _N H _HF/h|=149.9(2) MHz has been found. WithH _HF=?1,115(20) kG theg-factor of the 9/2⁺ [624] ground state of¹⁸³Os is deduced asg=(?)0.176(3).     

Locations of implanted 19F* atoms in Si,Ge and diamond studied through their nuclear quadrupole interactions

The Hartree-Fock cluster procedure was used to obtain the associated electronic distributions for ¹⁹F^* (I = 5/2, E ^x = 197 KeV excited nuclear state of the ¹⁹F atom) at possible sites in crystalline Si, Ge and diamond and to calculate nuclear quadrupole coupling constants v _Q and the asymmetry parameter η of the electric field gradient at the modelled sites. Lattice relaxation effects have been incorporated by employing a geometry optimization method to obtain minimum energy configurations for the clusters modelling each site. The intrabond (IB), antibonding (AB) and substitutional (S) sites in the bulk and the atop site on the surface were studied. From a comparison with v _Q and η values observed in time differential perturbed angular distribution (TDPAD) measurements we were able to identify the high frequency component in Si and Ge with ¹⁹F^* at the intrabond site. In diamond two high frequency components are observed. These are identified with ¹⁹F^* at intrabond and substitutional sites. For the low frequency site in Si and Ge the assignment is made to ¹⁹F^* implants at dangling bonds in the bulk resulting from implantation damage. In diamond none of the sites studied could provide lower frequency nuclear quadrupole parameters close to the observed ones. This revised version was published online in August 2006 with corrections to the Cover Date.     

Magnetic moment of 48Sc

Nuclear magnetic resonances were measured for ⁴⁸Sc and ^44mSc oriented at 8 mK in an Fe host metal. The magnetic hyperfine splitting frequencies at an external magnetic field of 0.2 T were determined to be 63.22(11) MHz and 64.81(1) MHz for ⁴⁸Sc and ^44mSc, respectively. With the known magnetic moment of $\mu \left( {^{44{\rm m}}\mbox{Sc}} \right)=+3.88\left( 1 \right) \mu _N $ , the magnetic moment of ⁴⁸Sc is deduced as $\left| {\mu \left( {^{48}\mbox{Sc}} \right)} \right|=3.785\left( {12} \right)\mu _N $ . The measured magnetic moment of ⁴⁸Sc is discussed in terms of the shell model using the effective interactions.     

Activation cross-sections of titanium isotopes at neutron energies of 13.5–14.8 MeV

The cross-sections for ~(46) Ti(n,2 n)~(45) Ti, ~(46) Ti(n,p)~(46 m+g) Sc+~(47) Ti(n,d*)~(46 m+g) Sc, ~(46)Ti(n,p)~(46 m+g) Sc, ~(47) Ti(n,p)~(47) Sc+~(48) Ti(n,d*)~(47) Sc, ~(47) Ti(n,p)~(47) Sc, ~(48) Ti(n,p)~(48) Sc+~(49) Ti(n,d*)~(48) Sc,~(48) Ti(n,p)~(48) Sc, and ~(50) Ti(n,α)~(47) Ca reactions were investigated around neutron energies of 13.5–14.8 Me V by means of the activation technique. Fast neutrons were produced by the~3 H(d,n)~4 He reaction. Neutron energies from different directions in the measurements were obtained in advance using the method of cross-section ratios for ~(90) Zr(n,2 n)~(89 m+g) Zr and ~(93) Nb(n,2 n)~(92 m) Nb reactions. The results obtained are analyzed and compared with the experimental data provided by the literature and verified nuclear data in the JEFF-3.3,CENDL-3.1, ENDF/B-VIII.0 libraries, as well as results calculated by Talys-1.9 code.     

15N excitation contribution to 48Ca(16O, 15N)49Sc reaction

The effect of ¹⁵N excitation process is studied in the reaction ⁴⁸Ca(¹⁶O, ¹⁵N)⁴⁹Sc. The excitation process is included into a generalized non-local optical potential for a scattersing ¹⁵N-⁴⁹Sc and is found to be responsible for a shift of a grazing peak in the exact finite-range DWBA calculation.     

Behavior of antimony above solid solubility in silicon produced by implantation and laser annealing

Abstract

Antimony implantation into <111> silicon was carried out at RT with a dose of 4.5 × 10¹⁵ cm^?2, energy 75 keV. For the annealing of the sample pulses of a Q-switched ruby laser were used with energy density of ～ 1.5 Joule/cm² and duration of 15–20 nsec. Hall effect measurement was applied to determine the electrical activity of the layers. Lattice location and the depth profile of Sb was studied by RBS and channeling technique. Measurements show that after laser annealing Sb occupies mostly substitutional sites in Si with 84% electrical activity. It has been shown that after laser annealing the concentration of Sb in lattice sites is almost an order of magnitude higher than the limit of solid solubility. Isochron and isothermal annealing of these samples up to 1150°C was carried out to study the kinetics of reverse annealing of antimony.     

H/D isotope effect for solubility of hydrogen in doped perovskites

A novel method for studying the H/D isotope separation effect in the “nonstoichiometric oxide-gas” system is suggested. The theoretical scheme of this method is represented for doped perovskites of the ABO₃ family, but this approach is also applicable to other compounds where the solubility of hydrogen is determined by the content of oxygen vacancies. The suggested approach is used to determine the H/D isotope effect in hydrogen solubility from the experimental data for proton-conducting oxides. The measurements have been taken using the nuclear microanalysis of fine-grain BaZr_0.9Y_0.1O_{3 − y} powders. The method is based on the study of the products of the ²H(d, p)³H nuclear reaction. The observed pronounced isotope effect is in quantitative agreement with our theoretical predictions.     

Effect of electron scavengers on the gamma radiolysis of H2S-Ch3Br systems

Abstract

The mechanism of mixed dimer negative ion formation in the gamma radiolysis of the gaseous system hydrogen sulphide-methyl bromide has been investigated using carbon tetrachloride and chloroform as the electron scavengers. The concentration of methane was measured gas-chromatographically. The measurements were performed at different total pressures.

ΔG(CH4)-1 is a linear function of [CH³Br][H2S]2/[Sc] (where Sc═CCl4 or CHCl3). On the basis of the above dependencies the mechanism of the formation of the (CH³Br-H³S)? ion was confirmed and the rate constant was calculated to be k=K-ka-kc/ka = 6.5 ×l0^?49 cm⁹ molecule ^?3s^?1     

In-beam Mössbauer study of atomic jump processes

Interstitial jump processes are studied using “in-beam Mössbauer technique” combining Coulomb excitation and recoil implantation. After implantation of Coulomb-excited⁵⁷Fe into metals (α-Zr, Al, Nb and Au) at low temperature, a relatively large part of the implanted atoms ends up on interstitial positions yielding large quadrupole splittings. Inα-Zr, the interstitial line shows a clear quadrupole relaxation accompanied by a sharp decrease of the resonance intensity between 40 K and 100 K. This effect is interpreted as localized fast jumps of⁵⁷Fe atoms in the octahedral cage of the hep Zr lattice. A preliminary result from a time-differential measurement onZr ⁵⁷Fe is presented.

     

Magnetic Hyperfine Fields of 151PmFe and 147NdNi

Low-temperature nuclear orientation (LTNO) experiments were performed on ¹⁵¹Pm implanted into iron and ¹⁴⁷Nd implanted into nickel. The γ-ray anisotropy measurements yielded values of the magnetic hyperfine field and the substitutional fractions of these ions in the host metals. An observed discrepancy between the substitutional fractions obtained from the 91 keV and 531 keV data on ¹⁴⁷NdNi is briefly discussed. This revised version was published online in September 2006 with corrections to the Cover Date.