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We prepared L10 ordered Fe50Pt50 thick-films on Cu substrates using the electroplating method and evaluated their high-temperature properties in the temperature range of 25-200°C. The Hc and the (BH)max at 150°C for the Fe50Pt50 films annealed by ordinary annealing method (700°C, 60 min) were 500 kA/m and 50 kJ/m3, respectively, and the thermal coefficient of Hc was -0.3%/°C. To improve the high-temperature properties, we employed a flash annealing method using an infrared furnace (8 kW). The flash annealing method improved the high-temperature properties (Hc = 700 kA/m, (BH)max = 70 kJ/m3 at 150°C) and the thermal coefficient (-0.21%/°C). The thermal stability of the films is comparable to those for Sm-Co-system magnets and better than for Nd-Fe-B-system ones. We, therefore, found the L10 ordered Fe50Pt50 films prepared by the electroplating and the flash annealing are one of the hopeful small magnets in the wide temperature range. [ABSTRACT FROM AUTHOR]

Recently, we investigated the effect of Na ion concentration in plating baths on the coercivity of L10 ordered Fe-Pt thick-film magnets prepared by an electroplating method and pointed out that a possibility of enhancement in the coercivity by the Na ion. In the present study, we electroplated Fe-Pt films on Cu substrates from plating baths with various concentrations of the NaCl for obtaining further evidence of the coercivity enhancement, focusing on the L10 ordering process of the film. From an x-ray diffraction analysis, we found that the Δ2θ, which has a diffraction peak split between (002) and (200) of the L10 ordered phase (fct structure), increased with increasing NaCl concentration under the same annealing conditions, and confirmed that the annealed films with large Δ2θ tend to show high coercivity. When varying the amount of NaCl in the plating bath, not only the Na ion concentration but also the Cl ion one varies, suggesting that the Cl ion also has a possibility of coercivity enhancement. In order not to vary the Cl ion concentration, we changed the reagent, which supplies the Na ions into the plating bath, from NaCl to Na2SO4. Consequently, the coercivity of the films for the baths with Na2SO4 (the Na ion) showed higher value compared with those for the baths without Na2SO4. From these results, we concluded that Na ion effectively works to enhance the L10 ordering and the coercivity for the electroplated Fe-Pt thick film-magnets. [ABSTRACT FROM AUTHOR]

The flexibility of magnetization of isotropic thick-film magnets enabled us to enhance the torque of a millimeter-size motor comprising a multipolar magnetized rotor compared to the torque of a miniaturized motor using an anisotropic Nd-Fe-B sintered magnet. In order to upgrade the torque of the small motor further, an increase in the remanence value of the isotropic films is indispensable. In this study, therefore, we prepared nano-composite Nd-Fe-B thick films by a high-speed PLD (pulsed laser deposition) method with a deposition rate of approximately 40 μm/h. Resultantly, the use of additive (Zr or Nb) was effective to enhance the coercivity value of Nd-Fe-B thick-film magnets with Nd-poor composition, however it was difficult to increase the remanence values. In order to apply the thick films to a micro-rotor, investigation on several experiments related to mechanical property was also carried out. [ABSTRACT FROM AUTHOR]

\Smx\Co5/ \alpha\-{\Fe} multilayered structures were synthesized by the pulsed laser deposition (PLD) method from rotating composite targets composed of \Smx\Co5 (x = 1-5) and \alpha\-\Fe segments. The deposited films were approximately 10~\mu\m in thickness. Transmission electron microscopy observations revealed that as-deposited films were composed of Sm-Co and \alpha\-\Fe layers, 780 layers in total, with the well-controlled thickness of approximately 10 nm, and they are crystallized into structures composed of Sm-Co and \alpha\-\Fe nanograins. The (BH)\max versus \Sm/(\Sm+\Co) curve at room temperature showed clear peaks and the (BH)\max value of 100~\kJ/m^3 was obtained. Although the obtained (BH)\max value of \Sm\-\Co/\alpha\-\Fe nanocomposite thick film-magnets was comparable to that of \Nd\-\Fe\-\B/\alpha\-\Fe at room temperature, it exceeded those of \Nd\-\Fe\-\B/\alpha\-\Fe nanolayered magnets and rapidly quenched (Nd, Dy)-Fe-B flakes at 150 ^\circ\C. The large (BH)\max value of the \Sm\-\Co/\alpha\-\Fe nanocomposite thick film-magnet at 150 ^\circ\C can be attributed to its small temperature coefficient of coercivity, -0.34\%/ ^\circ\C. [ABSTRACT FROM PUBLISHER]

Nd-Fe-B/\alpha-Fe multi-layered thick film-magnets were synthesized by pulse laser deposition (PLD) method from a Nd2.4Fe14B/\alpha-Fe composite target. In order to improve magnetic properties and their reproducibility, effects of the stacking period of Nd-Fe-B/\alpha-Fe layers, tp, the target-substrate distance, DTS, and the laser beam energy on a target, EL, on them were studied. The reproducibility of magnetic properties was improved significantly by decreasing EL. In particular, the standard deviation of the Nd content was suppressed within 3%, when EL was reduced from a value higher than 200 mJ/mm^2 to 25 mJ/mm^2. An increase in DTS and selection of a suitable tp value improved the maximum energy product (BH)\max. The largest (BH)max value obtained in this investigation was 112 kJ/m^3, which is higher than the values reported previously for isotropic film-magnets thicker than 10 \mum. Origins of superior magnetic properties were discussed from the viewpoints of suitable interlayer exchange interaction between Nd-Fe-B and \alpha-Fe layers and morphology of prepared film-magnets. [ABSTRACT FROM PUBLISHER]

In the preparation of a miniaturized rotor, a composite bonded magnet was fabricated by taking advantage of self-recoverability. A preformed magnet was synthesized by using incomplete three-dimensional network molecular structure which was formed under the optimum conditions at a temperature of 433 K, an alignment field of 1.4 MA/m, and a low compacting pressure of 50 MPa, respectively. The preformed ones were extruded and compressed into a ring-shaped magnet by using the self-recoverability at a pressure of 200 MPa and a temperature of 423 K under non-alignment-field. Through the process, a composite bonded magnet rotor in the shape of a ring could be prepared without a bonding layer. It was clarified that a 4 pole/6 slot DC brush less motor can be obtained by using the ring-shaped rotor comprising a parallel oriented anisotropic magnet with 7 mm in outer diameter, 158 kJ/M³ in (BH)max, and 6.2 Mg/m³ in density, respectively. Resultantly, the developed rotor enabled us to increase the S-T gradient by 1.75 times compared with that for a conventional isotropic Nd-Fe-B bonded magnet rotor with the same dimensions. [ABSTRACT FROM AUTHOR]

Co-Pt alloy him magnets were prepared by electrodeposition. After annealing as-deposited turns with face-centered-cubic (fcc) crystal structure, the structure of turns with 24 to 50 at.% Co content transformed 1mm disordered fcc phase to ordered face-centered-tetragonal (fct) L10 phase. It was clarified that Co-Pt film magnets with a Co content of 43 at.% have high coercivity of approximately 880 kA/m. [ABSTRACT FROM AUTHOR]

Isotropic Nd-Fe-B thick-film magnets were prepared by a vacuum arc deposition method followed by a pulse-annealing process. This paper reports the effect of discharge energy of the arc deposition on the magnetic properties of nanocomposite Nd-Fe-B/ \(\alpha \) -Fe thick-film magnets with Nb additive. Although the deposition rate decreased from approximately 20 to 5 \(\mu \) m/h due to the decrease in the energy from 44 to 11 J, the value of (BH) \(_{\max }\) could be improved by approximately 15 kJ/m \(^{3}\) . The result is considered to be attributed to the reduction in the the numbers and/or size of droplets. Resultantly, we could obtain a 29 \(\mu \) m thick Nd-Fe-B thick-films with the remanence, coercivity, and (BH) \(_{\max }\) values of 0.92 T, 390 kA/m, and 79 kJ/m \(^{3}\) , respectively. [ABSTRACT FROM AUTHOR]

Abstract: Anisotropic 270--thick composite-bonded magnets using the spherical fine powder together with HDDR- can be obtained, and the value of reached , which is extremely higher than that of conventional isotropic -bonded magnets. It was also confirmed that the thermal stability for the thin composite magnets was good. [Copyright &y& Elsevier]

For MEMS actuators that use permanent magnets, such as micro linear motors, micromachining and micro-magnetization of the magnets are needed in order to enhance and concentrate the magnetic field. This paper examines these processing technologies for magnets fabricated by pulsed laser deposition (PLD magnets). Magnets of this type can be more than a hundred microns thick, which makes them suitable for high power MEMS actuators. For the micromachining, we utilized molds with micro-grooves. These were filled with magnetic material deposited using Pr 2.0 Fe 14 B target, and then polished to decrease the surface roughness of the magnets to a few tens of μm. As a result, a linear array of magnets, each 100 μm wide and 50 μm high, was realized. For the micro-magnetization, partial magnetization reversal due to weakening of the coercivity as a result of laser heating while applying an external magnetic field was examined. To limit the magnetization reversal to the irradiated parts, heat conduction to the non-irradiated parts was restricted by using a thermally insulating glass mold, which was fabricated by micromachining. As a result, micro-magnetized magnets with a pole pitch of 200 μm were realized. The average measured magnetic flux density at a distance of 100 μm from the surface of the magnets was 43 mT (p-p), which corresponds to 88% of the value obtained by simulation. [ABSTRACT FROM AUTHOR]