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Volume 43, Issue 8
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[in Japanese]1996 Volume 43 Issue 8 Pages 950
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (53K) -
Nobuyuki Hiratsuka, Satoshi Suzuki, Koichi Kakizaki, Mitsuo Sugimoto1996 Volume 43 Issue 8 Pages 951-954
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTwo kinds of acicular cobalt ferrite fine particles which differed in size (long axis : about 1.2μm and 0.4μm) were prepared by conventional sintering method. Then two kinds of acicular cobalt ferrite tapes were fabricated with these fine particles and binder regins. The recording characteristics of these tapes were measured by using commercially available open reel tape deck. The output of the magnetic tape made of acicular particles, of the order of 1.2μm decreased linearly in the high density recording region because of a spacing loss. The output of the magnetic tape made of the acicular particles, of the order of 0.4μm increased in the high density recording region.
This was because the fine particles were densely packed in the medium and the roughness of the surface of the tape was smoothed by improving the dispersive quality.View full abstractDownload PDF (1723K) -
Tadachika Nakayama, Toshiyuki Matsui, Kenji Morii1996 Volume 43 Issue 8 Pages 955-960
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThin films of Mn2Sb were prepared by solid state mutual reactions in multilayered films consisting of Mn and Sb which were made by ion beam sputtering. Microstructure of the films was investigated by means of small and large angle X-ray diffraction (XRD), and cross-sectional transmission electron microscopy (TEM). Modulation wavelength of the multilayered films and discharging power for an ion source during sputtering determined the microstructural feature in the interdiffused region between the Mn and Sb layers, which was a dominant factor governing the texture development of the Mn2Sb phase on annealing. It can be concluded that the oriented nucleation process during deposition plays a significant role for the development of preferred orientation of the reacted compounds.View full abstractDownload PDF (2812K) -
Kouichi Masaki, Toshihiko Miura1996 Volume 43 Issue 8 Pages 961-965
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMetal particles, which are developing as advanced thin layer metal particulate media, have a coercive force of 167 to 191kA/m and a particle length of 60 to 80 nm. The particle form and its inner structure were examined with high resolution transmission electron microscopy and magnetic properties of these magnetic media. The particle length distribution which was defined as the standard deviation divided by the average length, was improved about 0.6 times of conventional metal particles.
The coercive force decreased with increasing particle length as well as aspect ratio(length/width). The value of rotational hysteresis integral was close to 1.1 with increasing the content of metal particles consisted of a single metal crystallite.
Larger content of single crystal metal particles or smaller number of metal crystallites in a metal particle seems to cause magnetization reversal similar to the coherent mode and large coercive force of 167kA/m or above. The enhanced characteristics of metal particle for extremely thin layer metal particulate media were achieved by the improvement of particle size and the particle size distribution of starting materials, and also the higher densification in the metal manufacturing processes.
There is still great room for improvement in the properties of metal particles which may be contributed to the extremely high density magnetic recording.View full abstractDownload PDF (1713K) -
Hiroshi Takechi, Tomoe Ohsaki, Noboru Shikatani, Masatsugu Morita1996 Volume 43 Issue 8 Pages 966-971
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of a small amount addition of many different oxides on the various properties of Mn-Zn soft ferrite was investigated. 21 kinds of oxides were widely chosen in terms of melting temperature and cation radii ratio (α value) of iron to additives. After 100ppm of additive was respectively added to the starting materials of Mn-Zn soft ferrite, they were fired under a condition. Initial permeability (μi) and core loss were measured in the alternative magnetic field of 100KHZ.
It was found that ti and core loss are improves by the addition of oxides with melting temperature of approximately 1, 000°C and a value of nearly 0.
The solution mechanism was discussed based on the data showing relation between density and grain size. The oxides with α value of nearly 0 was responsible for interfering with the grain boundary migration, resulting the formation of a fine and uniform microstructure. Small pores were also put off by the grain boundary diffusion of mätrix materials during final sintering while the grain boundary migration was inhibited by the additives having a high melting temperature and suitable α value.View full abstractDownload PDF (294K) -
Katsuhiko Igarashi, Takeshi Nomura1996 Volume 43 Issue 8 Pages 972-977
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTemperature dependence of inductance of MgZn ferrites has been investigated with reference to chemical compositions, amount of Fe2+ and microstructures. The dependence is strongly affected by ferrite composition, and maximum of inductance change is observed in stoichiometric composition. It was thought that the origin of composition dependence attributed to crystalline magnetic anisotropy (K1). In general, the ferrous ion..gives a positive contribution to K1. Relationship between Fe2+ and inductance change, however, can not be correlated in MgZn ferrites. Furthermore, grain size has less effect on the inductance change.
Inductance change is well correlated with between the number of etch pit and temperature dependence of inductance change. This result suggests that dislocations exist in the grain.View full abstractDownload PDF (1607K) -
Akihiko Saguchi, Wataru Takahashi, Yuji Kaneko, Naoyuki Ishigaki1996 Volume 43 Issue 8 Pages 978-983
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSNd-Fe-B type permanent magnets are produced by the powder metallurgical process. Therefore, the rough milling methods of making a coarse powder of the Nd-Fe-B alloy are of importance. In these methods, the characteristics of powders, i.e. shapes of powder, particle size distributions, oxygen content and chemical compositions, play a very important role on magnetic properties and manufacturing process of Nd-Fe-B sintered magnets. In order to clear these unknown problems, the Hydrogen Decrepitation (HD) method, which is one of the rough milling techniques, was especially employed. In this paper, the influences of both the hydrogen absorbing conditions and the alloy making conditions on the hydrogen absorbing behaviors in Nd-Fe-B alloy have been investigated using P -C-Tequipment. And the fundamental mechanism of hydrogen absorption into different phases of N d-Fe-B alloy was revealed.View full abstractDownload PDF (1931K) -
The Third ReportHiroshi Yamamoto, Rei Takeuchi1996 Volume 43 Issue 8 Pages 984-989
Published: August 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe purpose of this experiment is to investigate the effect of the catalytic reaction of NaGl and SrCO3 in the course of formation of the single phase of SrO⋅6Fe2O3 from the chemical coprecipitated powders( the Fe3+/Sr2+ ratio is 10.5). The preparation process is as follows ; coprecipitation→boiling→washing→drying→NaCl or SrCO3 addition(0-20 wt%)→heat treatment. The conditions determined as optimum for preparing the fine powders with the best values of σs=89.7×10-6 Wb⋅m/kg, HcJ= 401.8 kA/m and Tc=463°C are as follows : solution composition ; Fe3+/Sr2+=10.5 ; pH=13.0 ; NaCl=5wt% addition ; heat treatment ; 1000°C for 2hs in air ; particle size ; 0.2-0.3μm.View full abstractDownload PDF (1784K) -
Ryo Murakami, Hirofumi Kakuta, Hitoshi Takamura, Terumi Tanaka, Masuo ...1996 Volume 43 Issue 8 Pages 990-994
Published: August 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe appeared phases and magnetic properties of Sr1-x(La, AM)x ferrites (AM=Na, K) were studied. The prepared samples having the nominal composition of (Sr1-x⋅(La, AM)x)O⋅6Fe2O3, contain α-Fe2O3 phase and M-type ferrite phase. However the single phase of M-type ferrites with nominal compositions of (Sr1-x(La0.5Na0.5)x)O⋅(6-2x)Fe2O3 and (Sr1-x(La0.7K0.3)x)O⋅6-x)Fe2O3, where x=0.2 -0.8, was obtained by the selection of a tie-line composition. The c-axis of M-type ferrites became shoter with increasing x. Their magnetizations, Curie temperatures and anisotropy fields decreased with increasing the amount of substitution of La-AM for Sr.View full abstractDownload PDF (287K) -
Kenichiro Suwa, Hitoshi Taguchi, Taku Takeishi1996 Volume 43 Issue 8 Pages 995-1000
Published: August 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSCrystal stability and possibility as an anisotropic permanent magnet of W-type hexagonal ferrite with composition of Sr1-xBax [ZnLi0.5Fe0.5]Fe16O27 was investigated. In this study, we found that the amount of Fe2+ in the calcined compound gradually increases with increasing Sr. In the ball-milled compound followed by annealing at 900-1100°C, W phase of Sr[ZnLi0.5Fe0.5]⋅Fe16O27 partially decomposed into M phase and spinel phase. On the other hand, Ba [ZnLi0.5Fe0.5]Fe16O27 remained a single phase. It can be assumed that Fe2+ substituted for (Li+0.5+Fe3+0.5) or Zn2+, and oxidation such as Fe2+→Fe3+ givies rise to decomposition.
The grain size of Sr [ZnLi0.5Fe0.5]Fe16O27 and Ba [ZnLi0.5Fe0.5]Fe16O27 sintered at 1175-1225°C, respectively, was 0.3-5.0μm, their coercivity was less than 1000 Oe, and anisotropy energy (KA) and anisotropy field (HA) were estimated with about 60% of those of M-type ferrite. In conclusion, a preparation method of ferrite magnet hgaving more finer grains is necessitated for the practical use.View full abstractDownload PDF (1430K) -
Shuji Kawasaki, Mikio Takano, Yasuo Takeda1996 Volume 43 Issue 8 Pages 1001-1006
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAFe1-xCoxO3-δ (A=Sr, Ca) with minimized oxygen deficiency was prepared using high pressure technique. An oxider KCIO4 was encapsulated with the sample powder. The Co-substitution makes Fe3d electrons of AFeO3 more delocalized and induces metallic conduction and ferromagnetism. Cubic SrFe1-xCoxO3 shows ferromagnetism above 300 K for 0.4≤x≤0.9. From the composition dependence of unit cell volume, a possibility of negative magnetovolume effect has been raised. In orthorhombic CaFe1-xCoxO3 (0≤x≤0.5) Fe3d electrons seem to be more localized as judged from the magnetic hyperfine field measured by Mossbauer spectroscopy, and Tc is lower and the magnetization is smaller in comparison with the Sr-analogue. These seem to indicate that the σ* band is narrow in the Ca-phase because the Fe-O-Fe band is bent to -150.View full abstractDownload PDF (347K) -
Tetsuo Kato, Takeshi Kubono, Kenji Takamori, Eiichi Ohtake, Katsushi K ...1996 Volume 43 Issue 8 Pages 1007-1012
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSOn the sintered 18 percentt chromium 2 percent molybdenum iron magnetic alloys containing four sorts of silicon composition, the change in the value of coercive force which arises with the measuring speed to make a round of the hysteresis loop was measured and discussed. Similar changes have been observed in the apparent coercive force with the thickness of specimen for sintered alloy too. And the phenomenon was influenced by the change of resistivity owing to the silicon composition and the sintering temperature. These apparent coercive forces were constricted to the sole value when the inverse of measuring speed become to zero. This value may he the essential coercive force. But precise relationship of the change in apparent coercive force and resistivity could not make clear. The phenomenon is originated in the delay of magnetization and clearly depended on the ratio of μ∝/ρ at the nearest point of apparent coercive force.View full abstractDownload PDF (398K) -
Tetsuo Kato, Noriyoshi Kurata, Kazuhito Yamane, Takashi Huruya, Katsus ...1996 Volume 43 Issue 8 Pages 1013-1018
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSInfluence of the addition Fe-P powder on the AC magnetic property was studied on the sintered 12.5 percent chromium iron magnetic alloy. The DC magnetic property was highest at 0.6 percent addition. On the contrary, the highest AC magnetic property was attained at 0.8 percent addition. The DC magnetic property increased with the sintered density, but the AC magnetic property indicated the change as a decrease after an increase. An increase of the resistivity owing to the solid solution and the little remains on the addition up to 0.8 percent Fe-P causes an improvement of the AC magnetic property. However, an over addition above 0.8 percent causes an increase of the property and a decrease of the AC magnetic property in spite of an increase of the resistivity. These changes in the properties may be explained as the phenomena with the solid solution to the matrix caused by the liquid sintering under the 0.6 percent and the remaining of Fe-P to the grain boundary caused above the 0.8 percent.View full abstractDownload PDF (1821K) -
Hiroshi Yamamoto, Kashu Takahashi, Kazuya Tomii1996 Volume 43 Issue 8 Pages 1019-1024
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAn experiment was carried out to investigate the magnetic and physical properties of Sm3(Fe0.81Co0.10V0.09)29Nr and Sms(Fe0.75Co0.10Cr0.15)29Ny compounds. These compounds were prepared by nitrogenation of Sn (Fe0.81Co0.10V0.09)29 and Sm3(Fe0.75Co0.10Cr0.15)29 alloy powders (about 30μm) in high-purity nitrogen gas at pressure of 4.9MPa, and temperatures of 475-600°C for 0.5-5h. Sm3(Fe0.75Co0.10Cr0.15)29Ny alloy powders get a high coerrivily after nitrogenation. It was found when Sm3(Fe0.75Co0.10Cr0.15)29Nr powders were subsequently heated at 500-600°C for 3-25h under 98kPa of argon atmosphere, the value of coercivity of this compounds increased. The conditions determined as optimum for preparing the powders with best values of σs=139.5×10-6Wb-rndkg, HcJ=332kA/m, HA= 4.62MA/m, and Tc = 563.9t, are as follows: nitrogenation ; 600°C×1h, heat treatment ; 5501×10h. These powders were found to absorb approximately 7-8atoms of nitrogen per unit formula.View full abstractDownload PDF (1532K) -
Takafumi Satoh, Akio Hasebe, Etsuo Otsuki, Hiroshi Yamamoto, Kasyu Tak ...1996 Volume 43 Issue 8 Pages 1025-1029
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe microstructures of R3(Fe, M)29 compounds in the compositional range between 2-17 and 1-12 phases have been studied by using High-Resolution Transmission Electron Microscopy(HRTEM).
The purpose of this paper is to investigate the crystal structures and the lattice constant of Sm3(Fe, Co, M)29(M=Cr, V) compounds and their nitrided ones.
As a result, it was revealed by the electron diffraction and lattice image analysis that the crystal of the main phase in the nitrided samples has a hexagonal structure and its crystal form is not influenced by the nitrifying.
The lattice constant of Sm3(Fe0.75Co0.10Cr0.15)29 are a=2.432nm and c=2.088nm and the unit cell is composed by the stacking five cells of CaCu5 along a and c axes.View full abstractDownload PDF (4170K) -
Naohito Tsujii, Junhui He, Kazuyoshi Yoshimura, Koji Kosuge, Herwig Mi ...1996 Volume 43 Issue 8 Pages 1030-1035
Published: August 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSYbCu4Ag crystallizes in the cubic AuBe5-type structure where Yb is trivalent and shows dense Kondo behavior, while YbCu5 is known to have the hexagonal CaCu5-type structure where Yb is in a nonmagnetic divalent state. In this study, a pseudo-binary system YbCu5-xAgx was investigated. The powder Xray diffraction revealed that YbCu5-xAgx has the cubic AuBe5-type structure in the range of 0.125≤x≤1.0, while both the cubic and the hexagonal phase exist for 0≤x≤0.1, which suggests YbCu5 has also cubic AuBe5-type where Yb seems to be trivalent. Magnetic and transport properties show that YbCu5-xAgx is a dense Kondo system in which Kondo-temperature TK decreases continuously with the decrease of Ag-concentration x, causing the enhancement of the zerotemperature susceptibility x(O), the T2-coefficient A of electrical resistivity and the Sommerfeld coefficient γ of specific heat. The γ value was found to be enhanced to as large as 460mJ/mo1K2 in YbCu4.875Ag0.125. These results imply the cubic AuBe5-type YbCu5 is a dense-Kondo or a heavy-fermion system, in which γ reaches to about 500mJ/molK2.View full abstractDownload PDF (385K) -
Hiroaki Nishio, Takeshi Takahashi, Hitoshi Taguchi, Shinji Kamiya, Tad ...1996 Volume 43 Issue 8 Pages 1036-1041
Published: August 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe experimental results on Mössbauer measurement, chemical analysis (a ratio of Fe2+ to total Fe content), analyses of the rotational hysteresis loss (Wr) and the measurement of magnetic viscosity coefficient (Sv) for bacterial magnetic particles (BMP, particle diameter D=25-65 nm) were compared with those of Fe3O4 particles (D=18-45 nm) prepared by the chemical coprecipitated method. The value of saturation magnetization (Js) calculated from Mössbauer spectrum and the results of chemical analysis for BMP was 1.06×10-4 Wb m/kg. The curves of Wr/Ms versus H for BMP showed more sharp peaks than those of Fe3O4 particles. The rotational hysteresis integral (Rh) of BMP and Fe3O4 particles were 1.12 and 0.62, respectively. It was considered that they have different magnetization reversal mechanism. Sv value of BMP was 127 A/m, which was 50% smaller than that of Fe3O4 particles. The diameter (Dact) of activation volume (minimum unit volume of magnetization reversal) calculated from Sv and the critical diameter (Dc) obtained by considering the superparamagnetic behavior of BMP, were 39 and 22 nm, respectively. On the other hand, Fe3O4particles had smaller Dact (31nm) and Dc (18nm). It maybe concluded that the magnetic stability of BMP is better than that of Fe3O4 particles.View full abstractDownload PDF (432K) -
Study of Slurry Preparation ConditionsMasaki Maeda, Saburo Sano, Kiichi Oda, Yasuo Shibasaki1996 Volume 43 Issue 8 Pages 1045-1048
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSlip casting of high-purity mullite powder produced by coprecipitation method was studied to fabricate mullite engineering ceramic parts with complicated shapes. The characteristics of the slurries were examined by zeta-potential and viscosity measurements. The preparation conditions of well-dispersed slurries were determined using an organic polymer deflocculant. The most suitable deflocculant content was 0.2wt% of the solid. High-density green bodies (relative density=59.2%) were prepared by vacuum filtration with a polymer resin mold. High-density mullite ceramics (3.12-3.13 g/cm3) were obtained by sintering at 1650°C for 3hr in air.View full abstractDownload PDF (1746K) -
Atsushi Hitomi, Shigeki Sato, Chihiro Takahashi, Takeshi Nomura1996 Volume 43 Issue 8 Pages 1049-1054
Published: August 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe effects of calcination conditions on the electrical properties of BaTiO3-based PTC thermistorshave been studied. Samples quenched from 1350°C showed significantly lower resistivity than those quenched from 1300°C. Over the same temperature range, a large amount of oxygen was evolved and a divergence between grain and grain boundary resistance was observed. The grain boundary phase is mainly composed of Ba, Ti and Si, and is Ti-poor and Si-rich compared with the grain composition. It was shown that the occurence of Ba-Si-Ti phases at the grain boundaries depends on calcining conditions. It is thought that the grain boundary phase plays an important role in causing semiconductivity in the samples, and therefore in controlling their electrical properties.View full abstractDownload PDF (1940K) -
Hisashi Kaga, Kazunao Furumata, Tamotsu Akashi, Yoshihiro Taya, Syuich ...1996 Volume 43 Issue 8 Pages 1055-1060
Published: August 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe had reported the vacuum mechanofusion prpoedure, applied to Mo-A12O3 composite in air or under low pressure. This paper describes the result of trying the Mo particle coating on A12O3 core particles with different Mo content. It was found that the more Mo particles remained not consumed for the composite particles, as the Mo particle composition in the mixed particles increased. Furthermore, the Mo-A12O3 composite powders obtained was sintered to compact by spark plasma technique. As the results, it was found that the compact prepared from the composite powder was more improved in density than the compact prepared from the mixed powders, and this effect was remarkable in early stage of sintering. It was dear that the density of sintered compacts became higher as Mo content of composite particles increased.View full abstractDownload PDF (4774K)
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