bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleation and Abnormal Grain Growth of Alpha-A12O3 in Gamma-Alumina Matrix
Authors: Chou T. C. , Nieh T. G. 
Published: March 2011

AbstractThe microstructures of reactive sputter-deposited alumina films have been studied by transmission electron microscopy. The as-deposited films contained γ-A12O3 phase in an amorphous alumina matrix. Annealing of the films at 1200° C for 2 h resulted in nucleation and concurrent anomalous grain growth of α-A12O3 in a polycrystaUine γ-Al2O3 matrix which exhibited a layered microstructure and was strongly textured along [001]. The grain sizes of α-A12O3 varied from 3 to 20 μm, while the average grain size of γ-A12O3 was only about 50 nm. It appears that the nucleation kinetics of a-A12O3 was slow. As a result, the abnormal grain growth of α-A12O3 proceeded by consuming surrounding γ-Al2O3 grains. An atomic model is presented to explain the origin of layered structure in γ-A12O3. The nucleation mechanism of a-A12O3 in γ-alumina matrix is suggested. Orientation relationships between γ- and α-A12O3 are reported. The anomalous grain growth of α- A12O3 is discussed in terms of γ/α interface boundary migration.
Interaction Between Dislocations and NiFe2O4 Precipitates In A NiO Matrix
Authors: Summerfelt Scott R. , Carter C. Barry 
Published: March 2011

AbstractThree different types of dislocation interactions with NiFe2O4 (spinel crystal structure) precipitates in a NiO matrix have been studied. In the first, the movement of dislocations introduced by room temperature deformation is impeded by the spinel precipitates. Glide dislocations in the NiO with ½<011> Burgers vectors and {011} glide planes cannot pass through the spinel precipitates without forming stacking faults because the perfect NiO dislocations are partial dislocations in NiFe2O4. Many dislocation loops but no stacking faults were observed in the deformed samples indicating that the gliding dislocations formed the loops when they moved past the precipitates. In the second type of interactions, cusps were formed in the spinel-NiO interface at close to the dislocation loops when the sample was heat treated; the cusps indicate preferential dissolution of the spinel. In the final interaction, the dislocations were shown to act as preferential nucleation sites when spinel was precipitated from the NiO matrix. At slow nucleation rates, NiFe2O4 precipitated only on the dislocations; when the nucleation rate was increased, precipitation occurred both on and away from the dislocations. Precipitates which form at a dislocation may contain a stacking fault extending from the partial dislocation to a cusp in the spinel-NiO interface. When this occurred, the stacking faults were observed to be faceted parallel to either {111} or {011} planes.
Spin Polarized Low Energy Electron Microscopy of Surface Magnetic Structure
Authors: Altman M. S. , Pinkvos H. , Hurst J. , Poppa H. , Marx G. , Bauer E. 
Published: March 2011

ABSTRACTSpin polarized low energy electron microscopy (SPLEEM) has been developed for the high resolution imaging of surface magnetic structure. The existing LEEM ha.s been modified by the incorporation of a. GaAs-type spin polarized electron gun. Large image contrast arises due to the spin-dependent exchange scattering, whifle the st.in-orbit contribution vanishes uniquely for the normal incidence/exit geometry used here. Pixel by pixel image subtraction for incident electron beams of opposite polarization yields precisely the spatially resolved Bragg reflection asymmetry observed in spin polarized low energy electron diffraction. The shallow electron penetration depth arising from the strong coulombic interaction is advantageous for separating surface behavior from the normally overwhelning bulk. Therefore, the use of transversally polarizedI electron beams allows the determination of in-plane surface magnetization directions. Fnrthermore, the parallel illumination and detection of SPLEEM makes it possible to image quickly with a. resolution better than 500 Å in the present configuration. A useful and direct. comparison between surface magnetic, structural, and topological features is made possible by the augmentation of the unique imaging capabilities of conventional LEEM with the magnetic sensitivity of SPLEEM. In this manner, the magnetic domain structure of a Co (0001) surface and in-situ grown Co filmns on Mo(110) have been determined.
Magnetic Properties and Micromagnetic Character of RF Sputtered Co Thin Films on Thin Cr Underlayers
Authors: Yeh T. , Sivertsen J. M. , Judy J. H. 
Published: March 2011

ABSTRACTThe effect of thin Cr underlayers on the coercivity, the initial susceptibility, and micromagnetic structure of RF sputtered Co/Cr thin films have been studied. A reciprocal relationship between the initial susceptibility and the coercivity of the RF sputtered Co/Cr films were observed. Micromagnetic images of these Co/Cr films obtained by Fresnel mode Lorentz TEM revealed a refinement of the micromagnetic images correlated with a simultaneous increase in coercivity and decrease in initial susceptibility. Such behavior is expected in cases where the initial magnetization and magnetization reversal are hindered by the variation of local energy with the magnetic moment distribution. The interaction of the Cr underlayers with the Co magnetic overlayer very likely induces fluctuations in local magnetic energy of the Co films. Accordingly, the initial magnetization and magnetization reversal are likely to be impeded by fluctuations of the magnetic energy resulting in the observed increase in coercivity and decrease in initial susceptibility.
Interdiffusion Kinetics and Magnetic Properties of TA-Permalloy Multilayers
Authors: Hashim I. , Atwater H. A. , Kung K. T. Y. , Valletta R. M. 
Published: March 2011

ABSTRACTThe interdiffusion kinetics of ultrahigh vacuum deposited Ta/Ni81Fe19 short-period multilayers films have been investigated, and changes in microstructure were related to magnetic properties. Small angle X-ray diffraction and transmission electron microscopy were used to study layer morphology evolution and interdiffusion during post-growth isothermal annealing in the temperature range 300 – 600°C. The kinetic analysis suggests that interface roughening due to grain growth, and grain-boundary mediated diffusion of Ta occurs concurrently at early anneal times in the Ni81Fe19 films. Subsequent grainboundary and lattice diffusion of Ta lead to a reduction of magnetization and increase in coercivity of Ni81Fe19.
Dynamic Magnetic Permeability of Composite Iron Films
Authors: Antonov A. S. , Dyachkov A. L. , Lagar A. N. , Kov  , Panina L. V. 
Published: March 2011

ABSTRACTBoth frequency and field dependencies of the ac magnetic permeability in composite iron films were measured for different thickness of a conducting cell. Attention has been focused on additional dispersion caused by the skin effect. The data obtained are analyzed on the basis of the effective medium approximation.
Crystal Structure and Magnetic Properties of Co-Based Alloy Thin Film Prepared on Cr Underlayer With Good Crystallite Orientation
Authors: Kawanabe T. , Park J. G. , Naoe M. 
Published: March 2011

ABSTRACTCo85Cr15-xTax(x:0, 2at%)/Cr films with microscopically flat surface were investigated for high density recording media. These films were deposited on silicon wafer and glass substrates at the substrate temperature Ts of 350 °C at argon pressure as low as sub-mTorr by using Facing Targets Sputtering (FTS) apparatus. The elevating of Ts promoted the Cr(200) orientation in film plane, leading to the in-plane c-axis orientation of Co crystallites. Addition of some elements such as Si, Ge and Ta in Cr thin film was found to stabilize Cr(110) crystal orientation even at Ts of 300 °C.
The Effect of Annealing on NiFe/FeMn Thin Film Couples
Authors: Hwang Cherngye , Parker Michael A. , Howard J. Kent 
Published: March 2011

ABSTRACTThe antiferromagnctic FeMn thin film has been used to stabilize the domains in NiFe films by exchange-coupling, thus eliminating the Barkhauscn noise in magnetoresistive sensor designs. T'he strength of this exchange-coupling is highly dependent on the interfacial structure, as well as the interfacial composition of this NiFe/FeMn thin film couple. We have conducted isothermal, as well as isochronal anneals of NiFe/FeMn thin film couples, and monitored their magnetic properties, in particular the strength of their exchange-coupling. The strength of exchange-coupling, measured by the shift of the B-H loop obtained from a hysteresis loop tracer, increased monotonically with annealing time for isothermal anneals between 200 and 300 °C. At higher temperatures (up to 500°C), the interdiffusion between the two layers is so extensive that the NiFe layer loses its sort-magnetic properties and the coupling strength is degraded. Composition depth-profiling by scanning Auger analysis was conducted to study the interdiffusion profiles of the annealed samples. Cross-section transmission electron microscopy (XTEM) was used to study the microstructure, crystallography, and composition of these thin films after annealing. Micro-beam composition analysis was also carried out and the compositional profile obtained was compared to the Auger depth-profile results. Transmitted electron diffraction using selected area electron diffraction (SAED) and elongated probe micro-diffraction (EPMD) of XTEM samples was used to study the crystallography of these films.
Mössbauer Analyses of FeSiAl Films Sputtered in Ar or 4%N2 Mixture Atmosphere
Authors: Inoue K. , Tatsumi M. , Sakata T. , Tanabe S. , Ozeki T. , Shibata H. 
Published: March 2011

ABSTRACTMicrostructural differences between sendust(FeSiAl) films sputtered in pure Ar atmosphere and FeSiA1N films sputtered in Ar+4%N2 mixture atmosphere were measured using Mössbauer effect. These films were prepared by a conventional RF sputtering method. As a source for the Mössbauer measurement, 57Co was used.Before annealing, there are no differences between both films in Mössbauer spectra. The both patterns are observed as simple six-line spectra from Fe atoms in a disordered structure. After annealing, both patterns are not simple six-line spectra, which indicate there are more than two types Fe site in the crystal. A tremendous difference between both films appears in the spectra. 95% Fe atoms of FeSiAl film are at the two different sites of D03 structure. However, in FeSiAlN film, only 54& Fe atoms are at the D03 sites and about 30% Fe atoms are at different sites whose hyperfine field is about-250kOe. This value of hyperfine field is expected at a D03-like site with 5 Fe nearest neighbors. This D03-like site is explained as a site that one Fe atom is substituted for one D-site Si or Al atom in a D03 unit cell.No Fe-nitrides were observed in FeSiAlN films.
Thickness Effects on the Magnetic Hysteresis of Equiatomic CoPt Films
Authors: Tsoukatos A. , Hadjipanayis G. C. , Zhang Y. J. , Waite M. , Swann C. P. , Shah I. 
Published: March 2011

ABSTRACTThe magnetic hysteresis behavior of crystalline Co50Pt50films has been studied in samples with thickness in the range of 100-2000 Å. The room temperature coercivities of the as-grown films are of the order of 100 Oe. After annealing at 650°C the coercivities vary between 400 and 4300 Oe with the higher values obtained in thicker specimens. The high coercivities obtained are attributed to the hard magnetic phase CoPt with an ordered fct structure that is formed after annealing. The variaton of coercivity with thickness is examined and related to the crystal structure evolution and to grain size effects.
A New Class of Permanent Magnets - High Temperature Superconductors
Authors: Chen In-Gann , Liu Jay , Weinstein Roy 
Published: March 2011

ABSTRACTFor type II superconductors (SC), magnetic field can be trapped, or pinned due to persistent internal current. Upon magnetization, SC samples behave in some ways similar to a metallic permanent magnet. The trapped field is high and quasi-persistent, and we refer to it as a “magnet replica”. So far, nearly 1T @ 65 K, and over 0.4 T @ 77 K have been measured within small (about 1 × 1 × 0.6 cm3) melt-textured Yba2Cu3Ox (MT-Y123) samples. Based on our theoretical studies, extrapolation to larger scale magnets indicates that 2–4 Tesla in liquid Nitrogen (and even larger field at lower temperatures) is achievable with our high temperature superconductor (HTS) material. Using this effect, magnets with dipole, quadrupole, or more complicated configurations can be made of existing MT-Y123 material, thus bypassing the need for HTS wires. Two types of motors have been successfully constructed, using the trapped field in MT-Y123 samples.The spatial distribution of the trapped magnetic field on MT-Y123 materials has been studied. A phenomenological model has been developed to account for the trapped field intensity and profile in HTS samples. General features of magnet replicas by HTS will also be discussed.
Microstructure and Recording Noise of Thin Film Longitudinal Media
Authors: Yogi Tadashi , Nguyena Thao A. , Lambert Steven E. , Gorman Grace L. , Castillo Gil 
Published: March 2011

ABSTRACTThe magnetic and recording characteristics of Co-based thin film media are strongly influenced by microstructure. The media microstructural characteristics, in turn, depend on sputtering conditions of underlayers and magnetic layers. The role of Cr underlayer thickness and sputtering pressure have been reported previously. The present work examines the growth morphology and recording properties of a CoPtCr alloy on Cr underlayers where the deposition conditions such as sputtering pressure and rf bias were independently varied for the Cr underlayer and the magnetic layer. We find that the growth morphology of the magnetic layer is governed primarily by the deposition condition of the Cr underlayer. In particular, increased sputtering pressure for the Cr underlayer produces columnar morphology which induces isolation of the grains in the magnetic layer. This results in a significant reduction in the recording noise due to reduced intergrain exchange coupling. On the other hand, the application of ff bias during the deposition of the magnetic layer promotes more continuous magnetic grains, thereby increasing the recording noise. The observed trends in microstructure and recording noise can be understood qualitatively in terms of Thornton's microstructure diagram and the competition between micromorphological roughness and adatom mobility during the film growth.
Influence of Interfaces on Magnetooptical Effects in Multilayers
Authors: Višňovský Štefan 
Published: March 2011

ABSTRACTThe paper deals with the electromangetic theory of the optical interactions in planar multilayer (ML) structures displaying magnetic order. The main attention is focussed on the practically important configuration of normal incidence and polar magnetization in an originally isotropic medium. The procedure providing the information on the ML optical response is treated in detail. It assumes that the thickness and optical parameters in each layer entering the ML structure allong with the azimuth and ellipticity of the incident wave are given as the input data. The optical response is given in terms of the complex amplitudes of the reflected and transmitted waves from which the ML optical parameters, i.e. “Kerr” and “Faraday” effects, transmission, reflectivity, quality factor, etc., can be derived. The experience has shown that the procedure gives plausible results even for ML structures consisting of the layers the thicknesses of which are in the nanometer range, i. e. in the range where the interface effects play an important role.
Atomic Level Characterization of the Morphology of Phases in Chromindur Magnetic Alloys
Authors: Miller M. K , Camus P. P. , Hetherington M. G. 
Published: March 2011

ABSTRACTThe atom probe field ion microscope has been used to characterize the morphology and determine the compositions of the iron-rich a and chromium-enriched α′ phases produced during isothermal and step cooled heat treatments in a Chromindur II ductile permanent magnet alloy. The good magnetic properties of this material are due to a combination of the composition of the two phases and the isolated nature and size of the ferromagnetic a phase. The morphology of the a phase is produced as a result of the shape of the miscibility gap and the step-cooled heat treatment and is distinctly different from that formed during isothermal heat treatments.
Substrate-Deposition-Teiimperatijre Dependence of Perpendicular Magnetic Anisotropy in (Fe/Pt) Compositionally-Modulated Films
Authors: Iwata S. , Parkin S. S. P. , Nuri H. , Suzuki T. 
Published: March 2011

ABSTRACTA systematic study on magnetic properties of (Fc/Pt) compositionally-modulated films as a function of substrate-deposition-temperature has been carried out. For films with (2.5ÅFe/18ÅPt)×40, the intrinsic perpendicular magnetic anisotropy Kuis found to increase with decreasing temperature for all the sarmples deposited at temperatures from -114 °C to 220°C during deposition. The higher the substrate-deposition-temperature, the larger the Kuvalues become. This result implies a possible contribution from the magne to-elastic effect to the total anisotropy. However, a major part responsible for the perpendicular anisotropy may be found in other mechanisms. The saturation magnetization is found to exceed the value for pure Fe at temperatures lower than 180K.
A High Resolution TEM Specimen Thinning System
Authors: Clampitt R. , Ross G. G. , Phelan M. , Davies S. A. 
Published: March 2011

AbstractImprovements in specimen preparation for TEM analysis are being constantly sought, particularly in the study of microelectronics' materials and in failure analysis of devices. We describe here a compact commercial system capable of thinning (milling) selected regions of a specimen by means of a scanned focused ion beam of sub-micron spatial resolution.
Preparation of Large Area Cross-Sectional Tem Specimen of Semiconducting Heteroepitaxial Materials
Authors: Tamura M. , Aoki S. 
Published: March 2011

AbstractThe sample preparation procedures which enable us to observe large areas over a few tens of microns in one-dimension of semiconducting heteroepitaxial materials are described. The main principle involves the careful grinding and polishing of samples. In these procedures, another side thinning of the specimen after finishing initial side polishing is carried out using a sample platform by hand throughout all of the following steps. It is shown that for some typical examples of heteroepitaxial films general information concerning the film growth modes and structures, as well as the defect morphologies and natures introduced during growth can be effectively obtained by using the present technique.
The Syntheses of Nanoscale Metal Particles Produced by the Beam Induced Decomposition of Metal Hydrides and Azides in A Transmission Electron Microscope
Authors: Herley P. J. , Fitzsimons N. P. , Jones W. 
Published: March 2011

AbstractA novel and efficient technique for the generation of nanoscale metal particles by the electron beam decomposition of metal hydrides and azides is presented. Nanoscale metal particles down to ∼ 25 Å in diameter can be generated from metal hydrides e.g. copper from CuH and from metal azides e.g. silver from AgN3. The technique has been successfully applied to Be, Mg, Al, Cu, Pd, Ti, ‘Mn, Ni, Ag, Sn, Fe, Bi, Cd, Sb, Ln and Tl.
Fibxtem— Focussed Ion Beam Milling for TEM Sample Preparation
Authors: Basile David P. , Boylan Ron , Baker Brian , Hayes Kathy , Soza David 
Published: March 2011

AbstractIn the semiconductor industry, shrinking geometries and increasing process complexity have greatly increased the demand for TEM analysis of specific submicron regions. Until recently, samples of this nature have been difficult if not impossible to prepare. We have combined cross-sectional TEM sample preparation (XTEM) and the precise material sputtering of focussed ion beam milling (FIB) to thin samples to electron transparency. We call this sample preparation technique FIBXTEM.Three advantages of this technique are:1) The area of interest can be analyzed in the scanning electron microscope before final thinning;2) Any specific defect area becomes a candidate for TEM analysis, including failed sub-micron structures; and3) Samples are generally artifact-free and of uniform thickness.Key elements of the FIBXTEM technique include precision planar polishing, unique holders for mounting and transferring samples between systems, and the FIB-induced deposition of a sacrificial protective layer over the area of interest during ion thinning.This technique extends the use of TEM analysis into new areas of semiconductor process development and failure analysis. Recent applications for materials problem solving and failure analysis are discussed.
Rapid Plan View Fabrication of Semiconductor Tem Samples for Interface Strain and Grain Size Analysis
Authors: Cole M. W. , Flemish J. R. 
Published: March 2011

AbstractThis study presents novel methods for chemically preparing back-side and double-side etched, plan-view TEM samples without use of jet thinning instrumentation in order to examine both surfaces and interfaces. Examples are drawn from the semiconductor industry, but this technique can be generalized for use in most materials systems. The methodology for single-sided etching consists of flat lapping and mechanical dimpling followed by material selective chemical etching to electron transparency. Interface defect analysis of heterostructures is achieved via double-sided etching to electron transparency using the proper selective chemical etchants. These techniques are presented not as replacements for conventional cross-sectional preparatory techniques, but instead, as a means for rapid sample preparation for situations where a large number of samples must be analyzed quickly, or in cases where the necessary equipment is lacking for crosssection preparation.
Thickness Variations and Surface Layers in Ultramicrotomed Sections and Their Effects on Elemental Mapping
Authors: Malls T. , Steele D. 
Published: March 2011

AbstractWhile the thickness of ultramicrotomed sections is much more uniform than that of wedge-shaped foils, its variation is seen to be dependent on such factors as the type of material, use of embedding media, water bath interaction (anodic dissolution) and quality of the diamond knife edge. The latter also affects the thickness of surface oxides formed during sectioning. More deleterious surface layers are produced by partial breakdown and redeposition of embedding media under the electron beam. These artefacts indicate that ultramicrotomy is not the panacea for elemental X-ray mapping that might, at first thought, appear to be the case. For the example of a metal matrix composite, useable maps are obtainable, but even the best microtomed sections are limited in terms of mapping by factors such as the lengthy times for map acquisition caused by the low X-ray count rates resulting from thin specimens, particularly where low mass fractions are involved.
Application of Ultramicrotomy to Tem Specimen Preparation of Particulate Inclusion and Composite Materials.
Authors: Popoola O. O. , Cooper J. J. , Jakstys B. P. , Kriven W. M. 
Published: March 2011

AbstractUltramicrotomy has been used to prepare TEM specimens from nickel sulfide inclusions in plate glass and from calcium aluminate / polyvinyl alcohol composite materials. Microstructural studies showed that the inclusion probably contained at least two different phases, namely Ni7S6 and Ni3S2. Although microtomy-induced cracking and chatter were observed, important microstructural features such as twins and Moire patterns were preserved. The microchemistry of the polymer phase in the ceramic / polymer composite was precisely determined.