Sputter synthesis of RE-TM 2-17 type magnetic films with strong alignment of easy axes of grains.
Item
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Title
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Sputter synthesis of RE-TM 2-17 type magnetic films with strong alignment of easy axes of grains.
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Identifier
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AAI9029940
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identifier
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9029940
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Creator
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Hedge, Hari S.
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Contributor
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Adviser: Fred J. Cadieu
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Date
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1990
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Condensed Matter | Physics, General
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Abstract
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A systematic investigation of one-step sputter synthesis of RE-TM, 2-17 type permanent magnet films, from commercially available TDK Sm{dollar}\sb2{dollar}(CoFeCuZr){dollar}\sb{17}{dollar} type target material, has been carried out. The one-step film synthesis method involved the deposition of the magnet material on a preheated substrate through thermalized sputtering, in the presence of a magnetic field along the width of the substrate. In the synthesis of permanent magnets, whether in bulk or film form, to be able to approach the theoretically allowed values for energy products, it is important that the material be a highly dense aggregate of defect free, single domain-single crystals with strong alignment of easy magnetic axes in the desired direction. Our one step film synthesis method has largely succeeded in achieving this.;It was possible to vary the film properties, such as Sm content, 4{dollar}\pi{dollar}M{dollar}\rm \sb{lcub}s{rcub}{dollar}, B{dollar}\rm \sb{lcub}r{rcub}{dollar}, {dollar}\rm \sb{lcub}i{rcub}H\sb{lcub}c{rcub}{dollar}, easy axes orientation, crystal structure, etc. through sputter process control. The process control parameters were substrate temperature, sputter gas pressure, sputter gas species, etc..;To avoid formation of defects, due to energetic particle bombardment of the growing film surface, that could act as domain nucleation sites and thus lower the coercivity, and to achieve alignment of the easy axes of the grains in the direction of the applied magnetic field, it was necessary that the sputtered atoms be fully thermalized to energies of the order of an eV. This was achieved by the use of high sputtering gas pressures. It was found that lower the effective mass of the sputtering gas species, higher the required pressure. A thermalization model, that constructs the energy distribution of the sputtered atoms taking into account the energy dependent scattering cross-sections, at various distances for various gas species, has been presented. Through our thermalized sputtering technique, at optimum substrate temperatures, loop squareness (B{dollar}\rm \sb{lcub}r{rcub}{dollar}/4{dollar}\pi{dollar}M{dollar}\rm \sb{lcub}s{rcub}{dollar}) of 0.75 and energy products near 20MGOe were easily achieved.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
