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Full-Text Articles in Physics

Giant Energy Product In Nanostructured Two-Phase Magnets , Ralph Skomski, J.M.D. Coey Dec 1993

Giant Energy Product In Nanostructured Two-Phase Magnets , Ralph Skomski, J.M.D. Coey

Ralph Skomski Publications

Exchange hardening of nanostructured two-phase systems composed of an aligned hard phase and a soft phase with high magnetization is investigated using an approach which yields analytic nucleation fields from the micromagnetic vector equation, and accounts for interactions between the soft regions. In suitable structures the nucleation field is proportional to the volume-averaged anisotropy constant. For example, a multilayer composed of alternating 2.4 nm hard-magnetic Sm2Fe17N3 layers and 9 nm Fe65Co35 layers can have an energy product as high as 1 MJ/m3 (120 MG Oe), with a rare-earth content ...


The Behlen Observatory Variable Star Survey: Finding Charts And Light Curves For The First Ninety-Three Stars, Edward G. Schmidt, Darwin E. Reiswig Dec 1993

The Behlen Observatory Variable Star Survey: Finding Charts And Light Curves For The First Ninety-Three Stars, Edward G. Schmidt, Darwin E. Reiswig

Edward Schmidt Publications

In a previous paper, photometry for the first ninety-three stars in a photometric survey of variable stars was discussed. Finding charts, accurate coordinates, and light curves for those stars are presented here. The reliability of the coordinates from the General Catalogue of Variable Stars is discussed. The magnitude scale of the present photometry is compared with that of the Hubble Space Telescope Guide Star Catalogue.


Far-Ultraviolet Stellar Photometry: A Field In Orion, Edward G. Schmidt, George R. Carruthers Dec 1993

Far-Ultraviolet Stellar Photometry: A Field In Orion, Edward G. Schmidt, George R. Carruthers

Edward Schmidt Publications

Far-ultraviolet photometry for 625 objects in Orion is presented. These data were extracted from electrographic camera images obtained during sounding rocket flights in 1975 and 1982. The 1975 images were centered close to the belt of Orion while the 1982 images were centered ~9° further north. One hundred and fifty stars fell in the overlapping region and were observed with both cameras. Sixty-eight percent of the objects were tentatively identified with known stars using the SIMBAD database while another 24% are blends of objects too close together to separate with our resolution. As in previous studies, the majority of the ...


The Structural Homogeneity Of Boron Carbide Thin Films Fabricated Using Plasma-Enhanced Chemical Vapor Deposition From B5H9+Ch4, Sunwoo Lee, J. Mazurowski, W.L. O'Brien, Q.Y. Dong, J.J. Jia, T.A. Callcott, K.E. Miyano, D.L. Ederer, D.R. Mueller, Peter A. Dowben Dec 1993

The Structural Homogeneity Of Boron Carbide Thin Films Fabricated Using Plasma-Enhanced Chemical Vapor Deposition From B5H9+Ch4, Sunwoo Lee, J. Mazurowski, W.L. O'Brien, Q.Y. Dong, J.J. Jia, T.A. Callcott, K.E. Miyano, D.L. Ederer, D.R. Mueller, Peter A. Dowben

Peter Dowben Publications

Boron carbide thin films of several B/C ratios have been deposited on Si(111) using plasma-enhanced chemical vapor deposition from nido-pentaborane(9) (B5H9) and methane (CH4). X-ray diffraction studies of boron carbide thin films on Si(111) exhibited characteristic microcrystalline diffraction lines. Soft x-ray emission spectroscopy was used to verify that the local electronic structure and composition of each sample corresponded to a homogeneous solid solution boron carbide phase.


Photodetachment Of The 2P2 (3PE) State Of H-, Ning-Yi Du, Anthony F. Starace, Min-Qi Bao Nov 1993

Photodetachment Of The 2P2 (3PE) State Of H-, Ning-Yi Du, Anthony F. Starace, Min-Qi Bao

Anthony F. Starace Publications

Results of semiempirical, adiabatic hyperspherical calculations are presented for the photodetachment cross section of the process H- 2p2 (3Pe)+γ→H(n=2)+ e- at photon energies in the range from threshold to 0.125 a.u. above. We find the detachment cross section to have a maximum value of 482 Mb at 25.7 meV above threshold, in good agreement with results of close-coupling calculations by Jacobs, Bhatia, and Temkin [Astrophys. J. 242, 1278 (1980)]. In contrast to the close-coupling results, however, we find that the detachment cross section rises by a factor of more ...


The Temperature Dependence Of Perpendicular Anisotropy In Co/Pt And Co/Au Multilayer Films, H.Y. Zhang, Y.J. Wang, G.G. Zheng, J.X. Shen, Z.S. Shan, David J. Sellmyer Nov 1993

The Temperature Dependence Of Perpendicular Anisotropy In Co/Pt And Co/Au Multilayer Films, H.Y. Zhang, Y.J. Wang, G.G. Zheng, J.X. Shen, Z.S. Shan, David J. Sellmyer

David Sellmyer Publications

We report the temperature dependence of the effective perpendicular anisotropy and interface anisotropy in the temperature region of 80K to 290K for Co/Pt and Co/Au multilayers. Different temperature dependence of the interface anisotropy have been observed for these two types of multilayers. We speculate that the strain due to the lattice misfit may not be the main reason responsible for the perpendicular anisotropy in Co/Pt and Co/Au multilayers.


Structural And Magnetic Properties Of Lafe13-XSiX Nitrides, Z.X. Tang, X.H. Deng, George C. Hadjipanayis, V. Papaefthymiou, David J. Sellmyer Nov 1993

Structural And Magnetic Properties Of Lafe13-XSiX Nitrides, Z.X. Tang, X.H. Deng, George C. Hadjipanayis, V. Papaefthymiou, David J. Sellmyer

David Sellmyer Publications

LaFe13-xSix compounds were found to have two types of crystal structure; the face-centered cubic Na13--type (x ≤2.4) and the body-centered tetragonal Ce2Ni17Si9-type (3.5≤x≤5.0). Nitrogenation has a strong effect on the cubic phase, including a large lattice expansion (6.2 to 10.8 %), an increase of Curie temperature (52 to 80 K) and spontaneous magnetization ( ~10 %). The tetragonal phase, however, was not significantly affected by the nitrogenation.


Nucleation Field And Energy Product Of Aligned Two-Phase Magnets - Progress Towards The '1 Mj/M3' Magnet, Ralph Skomski, J.M.D. Coey Nov 1993

Nucleation Field And Energy Product Of Aligned Two-Phase Magnets - Progress Towards The '1 Mj/M3' Magnet, Ralph Skomski, J.M.D. Coey

Ralph Skomski Publications

Exchange hardening of nanostructured two-phase systems composed of an aligned hard phase and a soft phase with high magnetization is investigated using a micromagnetic approach which accounts for interactions between the soft regions. For Sm2Fe17N3 (2.5 nm)/Fe65Co35 (9 nm) multilayers an energy product as high as 1 MJ/m3 (120 MCOe) is predicted, witb a rare-earth content of only 5 wt %. Giant energy products may also be achieved in suitable cellular and disordered structures.


Triply Differential (E,2e) Cross Sections For He From Threshold To 50 Ev Above, C. Pan, Anthony F. Starace Oct 1993

Triply Differential (E,2e) Cross Sections For He From Threshold To 50 Ev Above, C. Pan, Anthony F. Starace

Anthony F. Starace Publications

Distorted wave calculations of the triply differential cross sections for electron-impact ionization of He are presented for electrons sharing ≤ 50 eV excess energy (Ex) and having the coplanar, θ12 = π geometry. The results are in good agreement with absolute experimental measurements of T. Rösel et al. [Phys. Rev. A 46 (1992) 2539-2552] and of A. J. Murray, M. B. Woolf, and F. H. Read [J. Phys. B 25 (1992) 3021-3036]. For final state electrons sharing 2 eV excess energy equally, many-body perturbation theory corrections to the authors' first order (e,2e) triply differential cross sections [Phys. Rev. A ...


Linear Dichroism In Photoemission From Oriented Molecules, N. A. Cherepkov, G. Schönhense Oct 1993

Linear Dichroism In Photoemission From Oriented Molecules, N. A. Cherepkov, G. Schönhense

Faculty Publications, Department of Physics and Astronomy

It is shown that oriented molecules reveal both Linear Dichroism (LD) and Linear Dichroism in the Angular Distribution (LDAD) of photoelectrons, which means a difference between photoelectron currents ejected at a definite angle by linearly polarized light of two mutually perpendicular polarizations. Measurements of LD and LDAD enable one to investigate the orientation of molecules and to make an essential step towards the complete quantum-mechanical experiment. As an example, LDAD in a model case of oriented heteronuclear diatomic molecules is presented.


Electric-Field Effects On H- Photodetachment With Excitation Of H(N=2), Ning-Yi Du, Ilya I. Fabrikant, Anthony F. Starace Oct 1993

Electric-Field Effects On H- Photodetachment With Excitation Of H(N=2), Ning-Yi Du, Ilya I. Fabrikant, Anthony F. Starace

Anthony F. Starace Publications

A theory of the photodetachment of hydrogen negative ions in an external static electric field with the production of hydrogen in excited states is developed. We use a combination of the frame-transformation theory and the Green’s-function method. The cross section in nonzero fields is expressed in terms of the photodetachment matrix elements for zero field. The latter are calculated using the adiabatic hyperspherical representation. For energies close to the threshold we use a smooth extrapolation of the zero-field photodetachment matrix elements down to threshold taking care to enforce the proper threshold behavior of cross sections for nonzero fields. The ...


Resonant Two-Color Detachment Of H- With Excitation Of H(N=2), Ning-Yi Du, Anthony F. Starace, N.A. Cherepkov Sep 1993

Resonant Two-Color Detachment Of H- With Excitation Of H(N=2), Ning-Yi Du, Anthony F. Starace, N.A. Cherepkov

Anthony F. Starace Publications

The cross sections for resonant two-color, two-photon detachment of H- with excitation of the degenerate H(2s) and H(2p) levels are calculated within a semiempirical adiabatic hyperspherical representation. The first photon, with energy ω1=0.4017 a.u., is resonant with the well-known Feshback 1P0 resonance below the H(n=2) threshold. The second photon, with energy ω2≥0.126 05 a.u., scans the energy region above the H(n=2) threshold over which long-range dipole-field-induced cross-section oscillations are predicted to occur. Such Gailitis-Damburg oscillations have not yet been observed experimentally. Results ...


Numerical Study Of A High-Order Quasiconserved Quantity In The Henon-Heiles Problem, Paul Finkler, C. Edward Jones, Glenn A. Sowell Sep 1993

Numerical Study Of A High-Order Quasiconserved Quantity In The Henon-Heiles Problem, Paul Finkler, C. Edward Jones, Glenn A. Sowell

Paul Finkler Papers

Recent efforts to derive and study a quasiconserved quantity K in the Henon-Heiles problem in terms of a single set of variables are discussed. Numerical results are given, showing how the value of such a quantity varies with time and order in a power-series expansion for K in terms of monomials of the coordinates and velocities. The lowest order in the power series for K corresponds to n =4 and the highest order to n =27, so that 24 orders are included in the series. The results are compared with an earlier study by the authors [Phys. Rev. A 42 ...


Short-Pulse Detachment Of H- In The Presence Of A Static Electric Field, Qiaoling Wang, Anthony F. Starace Sep 1993

Short-Pulse Detachment Of H- In The Presence Of A Static Electric Field, Qiaoling Wang, Anthony F. Starace

Anthony F. Starace Publications

Quantum interference effects occurring in photodetachment of H- in the presence of a uniform, static electric field are shown theoretically to be controllable through use of short laser pulses having characteristic times comparable to photodetached electron reflection times. In particular, calculated cross sections for single-photon detachment by two laser pulses that are delayed and phase shifted relative to one another are shown to oscillate as a function of the relative phases of the laser pulses at fixed photodetached electron energy.


Altering The Gd(0001) Surface Electronic Structure With Hydrogen Adsorption, Dongqi Li, Jiandi Zhang, Peter A. Dowben, M. Onellion Aug 1993

Altering The Gd(0001) Surface Electronic Structure With Hydrogen Adsorption, Dongqi Li, Jiandi Zhang, Peter A. Dowben, M. Onellion

Peter Dowben Publications

Hydrogen adsorption on Gd(0001) has been studied with angle-resolved photoemission. Hydrogen adsorption attenuates the surface state near EF on the clean Gd(0001) surfaces and induces two two-dimensional bands which are at 3.8 eV and about 6 eV near Γ¯. The state with the smaller binding energy has dz2 character at Γ¯ and disperses away from EF about 1 eV. The state at the greater binding energy disperses toward EF about 0.5–1 eV. At low substrate temperatures (120–130 K), the hydrogen chemisorption on the Gd(0001) surface results in a work-function decrease ...


Cellular Track Model For Study Of Heavy Ion Beams, Judy L. Shinn, Robert Katz, Francis A. Cucinotta, John W. Wilson, Duc M. Ngo Aug 1993

Cellular Track Model For Study Of Heavy Ion Beams, Judy L. Shinn, Robert Katz, Francis A. Cucinotta, John W. Wilson, Duc M. Ngo

Robert Katz Publications

Track theory is combined with a realistic model of a heavy ion beam to study the effects of nuclear fragmentation on cell survival and biological effectiveness . The effects of secondary reaction products are studied as a function of depth in a water column. Good agreement is found with experimental results for the survival of human T-1 cells exposed to monoenergetic carbon, neon, and argon beams under aerobic and hypoxic conditions. The present calculation, which includes the effect of target fragmentation, is a significant improvement over an earlier calculation because of the use of a vastly improved beam model with no ...


Diminishing Sign Anomaly And Scaling Behavior Of The Mixed-State Hall Resistivity In Tl2Ba2Ca2Cu3O10 Films Containing Columnar Defects, R.C. Budhani, Sy_Hwang Liou, Z.X. Cai Jul 1993

Diminishing Sign Anomaly And Scaling Behavior Of The Mixed-State Hall Resistivity In Tl2Ba2Ca2Cu3O10 Films Containing Columnar Defects, R.C. Budhani, Sy_Hwang Liou, Z.X. Cai

Si-Hwang Liou Publications

The issues of sign reversal of the Hall voltage and scaling between longitudinal (ρχχ) and Hall (ρχy) resistivities are studied in Tl2Ba2Ca2Cu3O10 films in which the vortex dynamics is drastically changed by flux pinning at heavy-ion-irradiation–induced linear defects. While the sign anomaly diminishes with increasing defect concentration, the power law ρχy∼ρχχ β , β=1.85±0.1, holds even after irradiation. This result shows that the scaling is a universal feature of the mixed state in this system. The sign anomaly, on the other hand ...


Symmetry Selection Rules For Vibrational Excitation By Resonant Electron Impact And A Unified Treatment Of Vibronic Coupling Between Resonances And To The Continuum: A Complete Symmetry Analysis Of Vibrational Excitation In Benzene, Gordon A. Gallup Jul 1993

Symmetry Selection Rules For Vibrational Excitation By Resonant Electron Impact And A Unified Treatment Of Vibronic Coupling Between Resonances And To The Continuum: A Complete Symmetry Analysis Of Vibrational Excitation In Benzene, Gordon A. Gallup

Gordon Gallup Publications

A symmetry analysis of the contributions to the transition operator from vibronic coupling provides symmetry selection rules for vibrational excitation by resonant electron impact in polyatomic molecules. In the context of electron scattering vibronic coupling operates in two modes. These are named internal and external vibronic coupling. Internal vibronic coupling operates within and among the quasibound states giving rise to the resonances. External vibronic coupling operates between the quasibound states and the continuum. We discuss the differences, particularly with respect to the angular distribution of electron scattering. A complete symmetry analysis of vibrational excitation is given using benzene as an ...


Nitrogen Diffusion In Sm2Fe17 And Local Elastic And Magnetic Properties, Ralph Skomski, J.M.D. Coey Jun 1993

Nitrogen Diffusion In Sm2Fe17 And Local Elastic And Magnetic Properties, Ralph Skomski, J.M.D. Coey

Ralph Skomski Publications

The reaction between nitrogen gas and an intermetallic compound is studied, with particular reference to Sm2Fe17, treating the Sm2Fe17Ny, system as a gas-solid solution. A simple lattice gas model is used to describe the reaction of nitrogen atoms with the metal lattice in terms of the net reaction energy U0= - 57 ± 5 kJ/mol. The equilibrium nitrogen concentration is calculated as a function of nitrogenation temperature and gas pressure. Refined diffusion parameters D0= 1.02 mm2/s and Ea= 133 kJ/mol, determined by thermopiezic analysis of the ...


High-Voltage Variable Resistor For Ion Energy Spectroscopy, Timothy J. Gay, V. D. Irby, S. P. Yallaly Jun 1993

High-Voltage Variable Resistor For Ion Energy Spectroscopy, Timothy J. Gay, V. D. Irby, S. P. Yallaly

Timothy J. Gay Publications

A high-voltage variable resistor was designed, built, and implemented to modify an ion-energy spectrometer for the study of ion-atom collisions in which the projectiles change charge. The resistor is remotely switchable from 0 to 2050 MΩ and has a voltage rating of 200 kV. The design criteria and the electrical and mechanical details of the apparatus are discussed. The design and construction of an ancillary device, comprising two precision resistive-divider voltmeters, are also discussed.


Experimental And Theoretical Cross Sections For Escherichia Coli Mutants B, B/R, And BS-1 After Heavy-Ion Irradiation, Robert Katz, Rashidah Zachariah Jun 1993

Experimental And Theoretical Cross Sections For Escherichia Coli Mutants B, B/R, And BS-1 After Heavy-Ion Irradiation, Robert Katz, Rashidah Zachariah

Robert Katz Publications

Data for the inactivation of three Escherichia coli mutants by energetic heavy ions are fitted by the track theory of a one-hit detector in an extended target mode. The respective E0’s are 46, 36.5, and 12.6 Gy for E. coli B, B/r, and Bs-1, and a0, the assumed target radius, is 0.5 μm for all three. The parameter E0, the D37 with γ rays, is measured directly, while a0 is fitted to the data. It is significant that neither a point target model nor calculations with a0= 0 ...


Light Diffraction By Field-Induced Non-Periodic Magnetic Domain Structures In Fecl2, Christian Binek May 1993

Light Diffraction By Field-Induced Non-Periodic Magnetic Domain Structures In Fecl2, Christian Binek

Christian Binek Publications

The magnetic-field-induced mixed phase of the meta magnet FeCl2 gives rise to reduced transmittivity of circularly polarized light. Within the framework of the diffraction theory of thin random magnetic phase gratings and the assumption of field-dependent refractive indices of the antiferromagnetic domains the field dependence of the transmission is perfectly modeled.


Magnetic Properties Of Epitaxial Single Crystal Ultrathin Fe3Si Films On Gaas (001), Sy_Hwang Liou, S.S. Malhotra, J.X. Shen, M. Hong, J. Kwo, H.S. Chen, J.P. Mannaerts May 1993

Magnetic Properties Of Epitaxial Single Crystal Ultrathin Fe3Si Films On Gaas (001), Sy_Hwang Liou, S.S. Malhotra, J.X. Shen, M. Hong, J. Kwo, H.S. Chen, J.P. Mannaerts

Si-Hwang Liou Publications

Magnetic properties of Fe3Si films with thickness from 2 to 210 monolayers (ML) epitaxially grown on GaAs (001) were studied using a superconducting quantum interference device and alternating gradient force magnetometers. Growth of these single-crystal intermetallic compound films were carried out in a multichamber molecular beam epitaxy (MBE) system. The samples were covered in situ with Au 50 Å thick to prevent oxidation when the samples were removed from the MBE chamber. All the films are ferromagnetic even for samples as thin as 2 ML. The easy magnetization direction of the films is parallel to the film surface ...


Behavior Of Disordered Co-Pd, Co-Ag, And Co-Mo Alloys In Multilayer Interfaces, Z.S. Shan, Ping He, C. Moore, John A. Woollam, David J. Sellmyer May 1993

Behavior Of Disordered Co-Pd, Co-Ag, And Co-Mo Alloys In Multilayer Interfaces, Z.S. Shan, Ping He, C. Moore, John A. Woollam, David J. Sellmyer

David Sellmyer Publications

Local environment effects are important for understanding interfacial magnetism in artificially structured multilayers. For this reason, stable and/or metastable disordered alloys CoxM1-x (M=Pd, Ag, Mo) were fabricated in a dc cosputtering system. The magnetization as a function of composition and temperature were measured and analyzed in terms of a mean-field model. The local environment effect on the Co moment from its Ag (or Mo) neighbors and the Pd moment from its Co neighbors are studied. It is found that the polarized Pd moment increases linearly with an increasing number of nearest Co neighbors and the ...


Electronic Structure Of Sm2Fe17NX Compounds, J.P. Woods, A.S. Fernando, Sitaram Jaswal, B.M. Patterson, D. Welipitiya, David J. Sellmyer May 1993

Electronic Structure Of Sm2Fe17NX Compounds, J.P. Woods, A.S. Fernando, Sitaram Jaswal, B.M. Patterson, D. Welipitiya, David J. Sellmyer

David Sellmyer Publications

Sm2Fe17Nx is of considerable current interest as a permanent-magnet material because of its enhanced Curie temperature and uniaxial anisotropy. The electronic structures of Sm2Fe17Nx for x=0 and x~2.6 have been studied with photoemission and spin-polarized calculations. The materials are prepared by arc melting and nitrogen is introduced by ion implantation. The nitrogen concentration is quantified with Auger electron spectroscopy. The Sm 4f electrons with binding energies between 6 and 10 eV are investigated with resonant photoemission using photon energies near 140 eV. The major features of ...


Nanostructural Effects And Interface Magnetism In Co/Pd Multilayers, Ping He, Z.-S. Shan, John A. Woollam, David J. Sellmyer May 1993

Nanostructural Effects And Interface Magnetism In Co/Pd Multilayers, Ping He, Z.-S. Shan, John A. Woollam, David J. Sellmyer

David Sellmyer Publications

A series of Co/Pd multilayers were made by dc magnetron sputter deposition on Al foil substrates. For these multilayered samples, Co layer thicknesses were less than 4 Å and Pd layers were varied from 4 to 22 Å. Sputtering rates were controlled by either sputtering power (10–50 W) or Ar sputtering pressure (3–15 mTorr). In both cases, lower deposition rates yielded higher perpendicular coercivity up to 2.6 kOe. Structures of the samples were studied using conventional θ -2θ x-ray diffractometry (XRD). It has been found that magnetic properties such as coercivity and saturation magnetization are sensitive ...


Crystal Field In Nitrogenated Rare-Earth Intermetallics, Ralph Skomski, M.D. Kuz'min, J.M.D. Coey May 1993

Crystal Field In Nitrogenated Rare-Earth Intermetallics, Ralph Skomski, M.D. Kuz'min, J.M.D. Coey

Ralph Skomski Publications

The crystal-field in Sm2Fe17N3- δ and Sm(Fe11Ti)N1- δ due to interstitial nitrogen has been investigated. Intrinsic parametrization in the superposition model allows separation of the crystal field created by a neighboring nitrogen atom from a purely geometrical factor, which is different for Sm2Fe17N3- δ and Sm( Fe11Ti) N1- δ Using published magnetic data, values for the intrinsic parameter A2 per nitrogen atom of A2=200± 60 Ka0-2 and A2=270±60 Ka0-2 for Sm2 ...


Characterization, Transport, And Magnetic Properties Of Co/Pd Multilayers Produced By Pulsed Laser Deposition, M. Enrech, Ralph Skomski, J.M.D. Coey, J.G. Lunney May 1993

Characterization, Transport, And Magnetic Properties Of Co/Pd Multilayers Produced By Pulsed Laser Deposition, M. Enrech, Ralph Skomski, J.M.D. Coey, J.G. Lunney

Ralph Skomski Publications

Metallic Co/Pd multilayers with equal layer thickness and periods ranging from 5 to 150 A were deposited using pulsed laser deposition. They have an fcc (111) texture and the diffraction patterns give clear evidence of a modulated period structure. From the period dependence of the in-plane electrical resistivity a diffuse interface between cobalt and palladium of thickness b= 6 ± 2 Å has been deduced. Magnetic, magnetoresistance, and Kerr-effect measurements indicate in-plane magnetization. In low fields (B0 < 10 mT) the magnetoresistanceis highly anisotropic, varying by ~2% in the transverse configuration and + 1% in the longitudinal configuration due to orbital moment of cobalt in the interface region. The shape of the Kerr-effect major hysteresis loop can be explained by the in-plane component of the anisotropy of the cobalt layers.


On The Role Of Zn In Sm2Fe17NX Permanent Magnets, P.A.P. Wendhausen, D. Eckert, A. Handstein, K.-H. Müller, G. Leitner, Ralph Skomski May 1993

On The Role Of Zn In Sm2Fe17NX Permanent Magnets, P.A.P. Wendhausen, D. Eckert, A. Handstein, K.-H. Müller, G. Leitner, Ralph Skomski

Ralph Skomski Publications

Coercivities up to 1.9 T were achieved by bonding micron-size Sm2Fe17Nx particles with zinc. X-ray analysis of Zn-bonded samples indicates the presence of the ZnFe Γ phase and no unreacted Zn, after heat treatment at about 390 °C for 100 min for samples with Zn content varying from 5 to 35 wt. %. The increase of coercivity occurs only for a more intense heat treatment, e.g., at 390 °C! for 300 min or 425 °C for 100 min. Differential scanning calorimetry (DSC) shows two exothermic peaks at 388 and 426 °C, but no endothermic ...


Interstitial Modification Of Rare-Earth Intermetallics, Ralph Skomski, S. Murray, S. Brennan, J.M.D. Coey May 1993

Interstitial Modification Of Rare-Earth Intermetallics, Ralph Skomski, S. Murray, S. Brennan, J.M.D. Coey

Ralph Skomski Publications

Interstitial modification of R2Fe17Zx is studied with R=Y, Sm, and Z=N, C, B, Si, and S. Equilibrium interstitial concentrations are calculated using a lattice gas model. For gas-solid reaction a low solubility is obtained at high temperatures, whereas a solid-solid reaction is predicted to yield R2Fe17Z1.5 in the high-temperature limit. Theoretical results are compared with data on Sm2Fe17Cx produced by solid-solid reaction at 500 °C. Volume expansions up to 4.8% were obtained, which corresponds to x≈2. The concentrations of interstitial ...