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Volume 48, Issue 2
Displaying 1-20 of 20 articles from this issue
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[in Japanese]2001 Volume 48 Issue 2 Pages 106
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (110K) -
Kazuharu Iwasaki, Tsutomu Yamamura2001 Volume 48 Issue 2 Pages 107-116
Published: February 15, 2001
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSα-FeOOH particles have been produced by the aging of amorphous ferric oxyhydroxide colloidal solution. The effects of addition of ions: OH-, Cl-, CO32-, PO43- and Co2+, on the process of formation and morphology of α-FeOOH particles have been clarified.
(1) The mechanism of formation of α-FeOOH crystal particles is considered as the dissolution-recrystallization process. The formation reaction of a-FeOOH crystal particles from the amorphous ferric oxyhydroxide can be expressed by a rate equation of the first order reaction.
(2) Since OH- and Cl- ions are selectively adsorptive to the side face parallel to c axis of α-FeOOH particles, the crystal growth of the side face is depressed.
(3) Since CO32- ion is not selectively adsorptive to the specific crystal plane, but is adsorbed on each plane of the a, b and c crystal planes homogeneously, the crystal growth of those planes is depressed. The recrystallization process of Fe(OH)4- ion is shifted from the surface reaction control to the diffusion control with increasing CO32- and Cl- ion concentrations.
(4) The asterisk type particles were produced in the limited narrow region of PO43- ion concentration. An asterisk type particle is heterogeneously junctioned particle of an α-Fe2O3 and several α-FeOOH crystals.View full abstractDownload PDF (7699K) -
Takeshi Mochizuki2001 Volume 48 Issue 2 Pages 117-125
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMost carrier cores for electrophotography are made from Cu-Zn or Ni-Zn ferrites. But in recent years, environmental experts are now warning that carriers, when placed in waste disposal sites after use, may be contaminating underground water. The experts explain that the nickel, copper, zinc and other hazardous heavy-metal ions disperse from the thrown-away soft ferrite carriers into the soil at waste disposal sites when exposed to acid rain; even if a waste disposal site has a concrete casing that seals itself off from the surrounding soil, heavy-metal ions can infiltrate into underground drinking water through cracks in the concrete. As a result, the use of these materials has been restricted by environmental regulations in many countries. In answer, we have succeeded in developing clean carrier cores that meet the environmental regulations of all countries. These clean carriers can be divided into magnetite and clean ferrites, both of which are produced by FDK's original production techniques. In particular, clean ferrites are new composite magnetic materials that can be designed to suit our customers' specific needs. We are hopeful that clean ferrites will become the main material of electrophotographic carrier cores in the near future.View full abstractDownload PDF (3382K) -
Isao Nakahata, Taku Murase, Atsuyuki Nakano2001 Volume 48 Issue 2 Pages 126-130
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn 1980, multilayer chip inductors were developed by thick film and co-firing technologies using low temperature sintered NiCuZn ferrites and Ag. The NiCuZn ferrites have been known as the only ones that can be sintered below the melting point of Ag, and have been used as the material of multilayer ferrite chip components. Since NiCuZn ferrites have a large magnetostriction, these ferrites are comparatively sensitive against stress, and therefore magnetic properties are easily deteriorated or changed by the stress. In this study, therefore, MgCuZn ferrites are chosen as a useful material for the multilayer ferrite chip components, because the magnetostriction (λ ?? ) of these ferrites is normally less than that of NiCuZn ferrites. MgCuZn ferrites, however, is generally sintered over 1000°C, so the investigations to sinter MgCuZn ferrites at the low temperature were performed.View full abstractDownload PDF (1434K) -
Atsuyuki Nakano, Isao Nakahata, Taku Murase2001 Volume 48 Issue 2 Pages 131-135
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIt was reported that electromagnetic properties of the multilayer chip ferrite components are influenced by the internal stresses and the diffusion of Ag buried in ferrite. As the magnetostriction of MgCuZn ferrites is lower than that of NiCuZn ferrites, it was expected that the multilayer chip inductor using MgCuZn ferrite would obtain higher magnetic properties than that using NiCuZn ferrite. Therefore MgCuZn ferrites with the low sintering temperature have been developed as the materials for the multilayer chip ferrite components. Under a compressive stress, the change in permeability of low temperature sintering MgCuZn ferrite was lower than that of low temperature sintering NiCuZn ferrite. Moreover, one might expected that the multilayer chip inductor using low temperature sintering MgCuZn ferrite would show a higher inductance than the chip using low temperature sintering NiCuZn ferrite. It is thought that low temperature sintering MgCuZn ferrite has the high potentialities of useful materials in the multilayer chip ferrite components, not only the multilayer chip inductors but also the multilayer LC and EMI chip filter components.View full abstractDownload PDF (353K) -
Isao Kanada, Taku Murase, Takeshi Nomura2001 Volume 48 Issue 2 Pages 136-139
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAs is known, the magnetic properties of ferrites are liable to be influenced by external stress. In this paper we describe our study of the effects of chemical composition and microstructure on the stress sensitivity of initial permeability of NiMgCuZn ferrites. When the external stress is applied to the ferrites, the reducing of the initial permeability due to the deficiency of Fe2O3 is observed. Furthermore, a finely dispersed grain size in microcrystalline structure is highly effective in stabilizing of initial permeability. As the compressive stress is applied parallel to the magnetic field, the maximum initial permeability of NiCuZn ferrite can be observed at 4 MPa. On the other hand, that of MgCuZn ferrite is observed at around 0 MPa. It seems possible to stabilize the initial permeability against the external stress by a further increase in composition ratio of NiO/(NiO + MgO).View full abstractDownload PDF (319K) -
Takuya Aoki, Taku Murase, Takeshi Nomura2001 Volume 48 Issue 2 Pages 140-144
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe bending strength of sintered ferrites has been studied for MgCuZn-, NiCuZn-, and MnZn-ferrites. It has been found that residual carbon content affects bending strength of these sintered ferrites. The sintered ferrites containing much residual carbon lower the bending strength. It is considered that PVA, which is added when the ferrite powder is granulated, remains as residual carbon in sintered ferrite after sintering. Control of the residual carbon content of sintered ferrite is one of the most important factors for obtaining high performance ferrite.View full abstractDownload PDF (1647K) -
Akihiro Nakamura, Takashi Kodama, Takehiro Konoike, Kunisaburo Tomono2001 Volume 48 Issue 2 Pages 145-149
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMn content dependence on the resistivity and on the reliability of NiCuZn ferrites were investigated to obtain highly reliable NiCuZn ferrites for multilayer chip components. The resistivity drastically increased by Mn addition and the obtained high resistivity was maintained even at high temperature. From the result of complex impedance analysis, it was found that the increase of resistivity might be controlled by the intra-grain resistivity. The result of high temperature life test indicated that Mn addition can be improved on the reliability of NiCuZn ferrites.View full abstractDownload PDF (1783K) -
Setsuo Yamamoto, Kazunori Nishimura, Yusuke Ojima, Hiroki Kurisu, Mits ...2001 Volume 48 Issue 2 Pages 150-154
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe small height inductor with a thin-film coils was designed for DC-DC converter circuit and fabricated. The thin-film coil was micro-formed on the smoothed ferrite substrate sintered at normal pressure. The size, inductance and allowable DC current of the fabricated inductor were 7.5mm×7.5mm×1.6mm (t), 23μH and 400 mA, respectively.View full abstractDownload PDF (5148K) -
Tabata Masahiro, Chohji Tetsuji2001 Volume 48 Issue 2 Pages 155-159
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSSingle phase of magnetite and nickelous ions substituted magnetite were respectively synthesized by bubbling oxygen into the ferrous and nickelous hydroxide suspension below 60°C. Single phase of magnetite was obtained at 20°C by setting the oxygen bubbling rate to 50 cm3min-1. The single phase of nickelous ions substituted magnetite (molar ratio of Ni-to-Fe =1: 9) was obtained by oxidation of the reaction solution under oxygen flow rate = 10cm3min-1 at 20°C. Because of the high solubility of oxygen, a low oxygen bubbling rate was necessary for the synthesis of spinel ferrite. The effect of addition of nickelous ions in the reaction solution on the formation of spinel phase was investigated. The formation of nickelous ions substituted magnetite was enhanced with a decrease in the oxygen bubbling rate. Nickelous ions inhibited the dissolution of hydroxide precipitate and forced the formation of δ-FeO(OH)-like phase.View full abstractDownload PDF (316K) -
Taku Murase, Takeshi Nomura2001 Volume 48 Issue 2 Pages 160-165
Published: February 15, 2001
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSA microstructure of YIG sintered ferrites are examined for the starting contents of Fe2O3 for its fabrications. For the higher Fe2O3 content in YIG single-phase range, the densification starts at the lower temperatures, then the grain growth is accelerated at high temperatures. In air atmosphere, it can occur at the lower temperatures, as compared with in oxygen atmosphere. As a result, many pores can be observed in YIG ferrites with high Fe2O3 contents sintered in air atmosphere. Further a small amount of Fe2+ ions is detected in sintered YIG ferrites, that is slightly large for the higher Fe2O3 content, or/and the lower oxygen partial pressure or/and the longer sintering time. Eventually the grain growth behavior of YIG ferrites can be considered to be closely related to the formation of ferrous ions in them.View full abstractDownload PDF (3401K) -
Tatsuya Nakamura, Yoji Okano, Mitsuharu Tabuchi, Tomonari Takeuchi2001 Volume 48 Issue 2 Pages 166-169
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSSr-ferrite sintered magnets were prepared by the spark plasma sintering method. This method brought the densification of Sr-ferrite at relatively low processing temperature and a remarkable short processing time. From the comparison of the magnetic properties of Sr-ferrite magnets produced by spark plasma sintering method with those by the usual ceramics method, a larger magnetization and a larger coercivity were easily and simultaneously obtained in the spark plasma sintering process. It was likely that such improvement in magnetic properties might be attributed to the densification with effective suppression of the ferrite grain growth by the spark plasma sintering method.View full abstractDownload PDF (2526K) -
Gaku Obara, Hiroshi Yamamoto2001 Volume 48 Issue 2 Pages 170-173
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSBa-La-Co M-type ferrite fine particles were prepared by mechanical compounding (M.C.) method using the planetary ball-mill and subsequent heat treatment. Experiments were carried out to investigate the effects of La2O3 and Co3O4 addition on the magnetic properties of Ba system M-type ferrite fine particles prepared by M.C. method. The optimum conditions for making M-type ferrite fine particles and some properties are as follows. Chemical composition: BaO·6.2Fe2O3 with addition of 2wt%La2O3 and 0.3wt%Co3O4, planetary ball-mill condition: 300rpm x 1h and heat treatment condition: 1150 °C x 1h in air. Typical magnetic and physical properties of the obtained powders are os=85.7×10-6Wb·m/kg, HcJ=414kA/m, Tc=450.5°C, and average particle size of 0.25μm.View full abstractDownload PDF (1446K) -
Ken Hirota, Masaru Yoshinaka, Osamu Yamaguchi2001 Volume 48 Issue 2 Pages 174-176
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDense composite materials (98.6% of theoretical) consisting of Super-Sendust (86.5Fe-6Si-4A1-3.5Niwt%) and MgFe2O4(75/25vol%), which have been fabricated by spark plasma sintering for 5 min at 850°C and 130 MPa, exhibit a high saturation magnetization density Β ?? of 1.2 T and a high electrical resistivity ρ of 1×10-2Ω·m. Permeabilities μ> 1000 at 1 kHz are obtained. Fine ferrite grains (-0.6μm) are located at the boundaries of the large spherical grains of Super-Sendust (-30μm).View full abstractDownload PDF (1580K) -
Naoaki Hayashi, Takahito Terashima, Mikio Takano2001 Volume 48 Issue 2 Pages 177-179
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWe have prepared high-quality epitaxial films of SrFeO3 by the pulsed laser deposition and a subsequent ozone oxidation. Mossbauer spectroscopy and resistance measurements revealed the good oxygen stoichiometry of the films. The resistivity of 500 Å-thick SrFeO3(001) film grown on the LSAT(001) substrate was by a factor of 4 lower than that of polycrystalline sample treated under high oxygen pressure of 500 atm. A positive sign of the Hall coefficient in the paramagnetic temperature range strongly supports the picture that the conduction carriers are oxygen holes. The temperature dependence of the resistivity showed a change of the curvature at around 110K, corresponding to the phase transition from the paramagnetic state to the screw-spin type antiferromagnetic one.View full abstractDownload PDF (1932K) -
Preparation and Properties of the Micro-Sized Wires and Dots of the Perovskite-Type Manganese OxidesAtsunobu Masuno, Takahito Terashima, Mikio Takano2001 Volume 48 Issue 2 Pages 180-183
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWires and dots of the perovskite-type manganese oxides with the dimension of micrometer were experimentally fabricated by the electron-beam lithography method and Ar-ion dry etching of those oxide thin films. The La0.7Sr0.3MnO3 thin films were prepared by the pulsed laser deposition (PLD) method with a KrF excimer laser. The wire of 1μm width showed a larger magnetoresistance than that of the thin film. Definite magnetic force microscope (MFM) images revealing movement of the domain structure were observed for the 2×2 μm square dots under an applied in-plane magnetic field.View full abstractDownload PDF (3101K) -
Hiroshi Yamamoto, Shigenori Matsumoto, Akira Fukuno2001 Volume 48 Issue 2 Pages 184-190
Published: February 15, 2001
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSExperiments were carried out to investigate the magnetic properties of Sm-Fe-Co-Nb-Zr system nitriding compounds with TbCu7-type structure. Sm8(Fe0.95Co0.05)88.0Nb4.0-xZrx (X=0-4) alloy ribbons were prepared by the single roller rapid-quenching method, and the effects of alloy composition, and conditions of heat-treatment and nitrogenation, were examined with regards to their magnetic properties. The optimum preparation conditions of the compounds are as follows. Composition: {Sm8(Fe0.95Co0.05)88.0Nb3.0Zr1.0}86.7N13.3, roller velocity: 50m/s, heat treatment: 725°C×60 min in high-purity Ar atmosphere, and nitriding condition: 400°C×15h in high-purity N2 gas. Typical magnetic properties of the obtained compound are HcJ=678.0 kA/m (8.52 kOe), σr= 120.0×10-6 Wb·m/kg (91.64 emu/g), σ1.6M =162.1×10-6 Wb·m/kg (129.0 emu/g), (BH)max=123.4 kJ/m3 (15.5 MGOe), and Tc= 508°C. The value of (BH)max for the compression-molded isotropic bonded magnet prepared from the {Sm8(Fe0.95Co0.05)88.0Nb3.0Zr1.0}86.7N13.3 powder is 81.1 kJ/m3(10.2 MGOe), when the density of the bonded magnet is 5.9 Mg/m3.View full abstractDownload PDF (1685K) -
Katsushi Kusaka, Akihisa Shibata, Tetsuya Kondo2001 Volume 48 Issue 2 Pages 191-195
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe objective of this study is mainly to elucidate the effect of sulfuric acid corrosion on DC/AC magnetic properties of 434L-type PM stainless steels with Si of 1 and 2 wt%. DC/AC magnetic measurements were experimentally carried out before and after the boiling test in 5% of sulfuric acid, together with the radial crushing strength test. Finally, these data were numerated in terms of degradation ratio (ΔX/X).
The result obtained were summarized as follows:
(1) As for sintered and HIPed materials, corrosive weight loss (ΔW) wholly decreased with the rise of sintered density (ρ) except for the passivative region of p=7-7.5 Mg/m3, though there is a little difference of ΔW in the addition of Si 1 to 2wt%.
(2) DC magnetic properties, especially magnetic induction (B) was linearly degraded with the rise of ΔW, where ΔB/B was extrapolated to nearly zero when satisfying ΔW=0.
(3) As an example experiment of maximum permeability (μm), Δμm/μm was extensively scattered in the region of 0.1-0.3 though μm almost bears no correlation to ΔW.
(4) The fraction of specific permeability (μa), typical of AC magnetic properties, Δμa/μa also had more extensively scattered at higher frequency -100 kHz.
(5) Radially crushed strength (σ) shows the degradation ratio of as much as 0.6 regardless of weight loss, probably because of being sensitive to surface conditions.View full abstractDownload PDF (1836K) -
Shinichiro Ishibashi, Toshihiko Sato, Toshimitu Akiba, Masaru Yokoyama ...2001 Volume 48 Issue 2 Pages 196-200
Published: February 15, 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSObservation was made in this study with the change of the magnetization using earthworms as specimen animals for the test. Therefore an earthworm which was dehydrated to be cut down into 3 portions, i.e. the head, body, and tail was measured by VSM. It is revealed from this observation that very little magnetization was found in the head, and the values of the magnetization are made greater in the order of the body and tail. The magnetite (Fe3O4) however taken up hereby was 1g/m2-50g/m2 in amount, respectively. Furthermore by keeping the magnetite in the individual containers, the behavior of the earthworms dependent on whether the magnetite is in existence or not was observed.
Meanwhile with the earthworms fed by the earth baits having the magnetization of 0.020 T and 0.033 T, the values of the magnetization of such earthworms are greater than those of the earthworms fed by the normal baits with respect to either portion of the head, body, and tails. Furthermore with the earthworms dropping at that time, the value of the magnetization is considerably great. This might stem from the reason that the earthworms themselves magnetization values are closely related with the magnetization of the soil. Meanwhile measurement of the pH values made it clear that the earth baits and droppings were alkaline, and it is made plain from this that as the magnetization value was made greater, an increasing tendency was noted with the alkalinity.View full abstractDownload PDF (441K) -
2001 Volume 48 Issue 2 Pages 205
Published: 2001
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (935K)
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