The three most common instruments for high-sensitivity magnetization measurements (the vibrating-sample magnetometer, the alternating gradient magnetometer, and the SQUID magnetometer) are described and their limiting sensitivities are discussed. The advantages and disadvantages of each are described. Magnetometers using micro-machined force detectors are briefly mentioned.

Phase evolution and magnetic properties of (Nd0.95La0.05)(9.5 similar to 11)Febal.M2B10.5, where M=Cr, Ti, Mb, V, Mo, Zr, Hf, Ta, Mn or W, melt spun ribbons have been investigated. Almost all the alloy ribbons, except for (Nd0.95La0.05)(9.5)Fe78M2B10.5 (M=Mo and Mn), consist merely two magnetic phases, namely alpha-Fe and R2Fe14B, which display a better combination of H-i(c) and magnetic energy product. Remanence (B-r) and coercivity (H-i(c)) values in the range of 8.0 to 9.1 kG and 9.5 to 18.9 kOe, respectively, can be achieved. Among compositions studied, the Ti and W-substitutions were found to be most effective in increasing the Br and H-i(c), respectively. For a fixed refractory metal substitution, namely, M=Cr, Ti or Mb, an increase in the total rare earth concentration resulted in nanocomposites of small grain sizes and a high volume fraction of the R2Fe14B phase, leading to an increase in the magnetic properties.

The demagnetization curves for the nanocrystalline Nd-Fe-B magnets of the stoichiometric composition were calculated by using the finite element technique of micromagnetism. The curve, especially H-i(c) become smaller with increase of N. The most small H-i(c) from a series of the curves along different field directions is closer to that for N=infinity. H-i(c) increases with increase of L, and are close or some what smaller than that the experimental values should be.

The influence of quenching technology, annealing temperature and time on the structures and magnetic properties of Nd8Fe83Co3B6 nanocomposite magnets was investigated. The results show that the alpha-Fe/Nd2Fe14B nanocomposite magnet containing a small amount of B is difficult to form amorphous state. The magnetic properties of 26 m/s quenched Nd8Fe83Co3B6 powders annealed at 640 degrees Cx480 s reach H-i(c)=513 kA/lm, B-r=1.05 T and (BH)(max)=92.0 kJ/m(3). The grain size is Dalpha-Fe=21.5 nm and D-Nd2Fe14B=30.2 nm.

The magnetic properties and microstructure of diffusion annealed [Ta/Nd/NdFeB/Nd/Ta] thin films have been investigated. The films were deposited on Si substrate with various thickness ratio of Nd/NdFeB layer (R=0 similar to 3.3), then diffused and crystallized by annealing at 650 degrees C for 10 min. The film without Nd layer showed soft magnetic behavior and high content of alpha-Fe phase. The films with R greater than or equal to 1 showed good hard magnetic properties with the high coercivity of about 20 kOe.

In Sm2Fe17-xMx(M=Al, Ga), there was observed a kind of spin-reorientation with temperature, and in (Sm1-xTmx)(2)Fe14Al3, the anisotrophy field H-A increases as high as 20% from 5.4 up to 6.5 kOe with T-m.

The effect of a partial substitution of Zr, Ga, Co and Ga, Co, Ga and Zr, respectively for Fe on the structure and magnetic properties of Nd8.4Fe87.1B4.5 alloy prepared by mechanical alloying has been studied in detail. It has been shown that, intrinsic coercivity mu(o)H(c), and maximum magnetic energy product (BH)(max) increase for only Zr or Ga-containing samples, which is mainly due to the refinement of soft grains. The combined addition of Co and Ga is less effective for improving mu(o)H(c) and (BH)(max) than the respective addition of Co or Ga, which may be due to the formation of CsCl-type CoGa. mu(o)H(c) and (BH)(max) for combined Co, Ga, Zr-added alloy are higher than those for the combined Co, Ga-added alloy but lower than those for only Zr-containing alloy.

In this article, the quenched Nd4.5Fe75Co1Si1B18.5 ribbons were prepared, and the structures and properties were investigated. The results show that the change of structures of Nd4.5Fe75Co1Si1B18.5 quenched amorphous ribbons is Am-->Am' +Fe3B+ Nd2Fe23B3+ Nd2Fe14B-->Fe-3 B+Nd2Fe14B when it is heated. The effect of crystallizing treatment temperature and time on the magnetic properties of the quenched alloy was studied. The magnetic properties of 16 m/s quenched ribbons for 710 degrees Cx1200 s crystallizing treatment reach H-i(c)=238.6 kA/m, B-r=0.8987 T and (BH)(max)=51.39 kJ/m(3). The grain size is about D-Fe3B=32 nm and D-Nd2Fe14B=22 nm.

The alloy with nominal composition Sm-2(Fe0.94Ti0.06)(l7) is prepared by are-melting, hydrogenation and nitrogenation processes. The Sm-2(Fe0.94Ti0.06)(17) alloy has a single phase of Sm-3(Fe, Ti)(29) with the Nd-3(Fe, Ti)(29)-type structure. The corresponding hydride phase with the same phase structure of the parent alloy was formed after a hydrogen decrepitation (HD) process at 300 degrees C. The hydrogenation at 800 degrees C mainly shows a HDDR process. The HD and nitrogenation at 500 degrees C result in increasing the Curie temperature of the alloy by 72 degrees C and by 158 degrees C due to lattice expansions, respectively. The anisotropic and isotropic Sm-3(Fe, Ti)(29)Ny magnets are obtained after HD, HDDR and the consequent nitrogenation, respectively. The optimum magnetic properties of Sm-3(Fe, Ti)(29)Ny powders achieved in the above two processes are: (i) B-r=0.82 T, H-i(c)=4.48 kA/cm, (BH)(max)=54.3 kJ/m(3), (ii) B-r=0.68 T, H-i(c)=8.14 kA/cm, (BH)(max)=66.4 kJ/m(3).

The structure and magnetic properties of SmyFe(100-1.5)yC(0.5y)(y=8 similar to 20) alloys prepared by mechanical alloying (MA) from Sm, Fe and graphite have been investigated systematically. In order to improve hard magnetic properties of the alloys prepared by mechanical alloying, a new method consisting of re-milling and re-annealing was developed. After being re-milled and re-annealed, the Curie temperature T-C of the Sm-Fe-C alloys changes. The T-C of 2:17 phase increases, whereas the T-C of 2:14:1 phase decreases. After being re-annealed at low temperatures, the grain sizes of hard phases are smaller than those in the alloys annealed at high temperatures. The effects of Co or Ti substitution for Fe are studied.

Using ball milling and single direction pressing, we can produce high performance NdFeB sintered' magnets. The oxygen content of sintered magnets can be controlled under 1500x10(-6) and the magnetic performance can be improved by using low oxygen processing. The high performance NdFeB sintered magnets with B-r=(1.4+/-0.2)T, (j)H(c)greater than or equal to 796kA/m and (BH)(max)=(390+/-16) kJ/m(3), have been batch produced.

The general hot deformation process consists of two steps. hot pressing and die-upsetting in order to obtain the anisotropic NdFeB magnet. This is the first report that the high anisotropy NdFeB magnets can be fabricated by single stroke hot deforming the isotropic magnet. The magnetic properties of those materials are: coercivity H-i(c) similar to 11 kOe, remanence B-r similar to 12 kG, and the maximum energy product (BH)(max) similar to 28 MG . Oe.

The discovery of the first Fe-based ferromagnetic amorphous alloy in 1966 had made an impact on conventional magnetic materials because of its unique properties. Since then, a number of amorphous magnetic materials have been successfully developed and used in a wide variety of applications. A brief review of R & D activities on amorphous soft magnetic materials in China is given from the beginning to the present in a somewhat chronological order, followed by a brief introduction to their applications on electric and electronic industries. An analysis and a prospect of Chinese market of such amorphous materials are also presented.

A siliconizing process to manufacture 6.5% Si steel sheet has been developed. Electric components. such as transformers and reactors are made easily from 6.5% Si steel sheet. However, improved workability is desirable to increase the applications. Therefore the improvement of workability of 6.5% Si steel sheet was investigated, and the results were obtained as follows: (a) workability of 6.5% Si steel sheet is deteriorated by grain boundary oxidization, (b) grain boundary oxidization can be restrained by the addition of C. Workability and magnetic properties of 6.5% Si steel sheet with C addition are discussed. Furthermore, it was found that the workability of high Si steel sheet was improved remarkably by varying the Si content gradient along the thickness without deterioration of high frequency magnetic properties. This newly developed magnetic gradient high Si steel sheet is also discussed.

We investigated the variation of permeability spectra and relaxation frequency in Go-based amorphous ribbon annealed by pulsed Nd:YAG laser at various annealing energy E-a. The complex permeability spectra varies sensitively with the annealing energy, where the spectra could be decomposed into two contributions from domain wall motion. mu(dw)(f) and rotational magnetization mu(rot)(f) by analyzing the measured spectra as a function of driving ac field amplitude. The magnitude of mu(dw)(f) and mu(rot)(f) in dc limit shows maximum at E-a = 176 mJ. The maximum relaxation frequency for rotational magnetization, determined by mu"(f) curve, is about 700 kHz at E-a=62 mJ but that for wall motion is about 26 kHz at 230 mJ. These variations reflect the increase of magnetic softness and microstructural change by the annealing.

We investigated the effect of treatment temperature on the magnetic property of iron nitride foils irradiated with nitrogen plasma. The iron nitride foils irradiated with nitrogen plasma were composed of epsilon-Fe(2)similar to(3)N, gamma'-Fe4N and gamma nitrogen austenite in alpha-Fe of the matrix. The saturation magnetization of the iron nitride foils decreased with increasing the surface temperature. The coercive force of the iron nitride foils increased with increasing the surface temperature.

The mu(i)-T curves of the alloy Fe73.5CU1Nb3Si13.5B9 in the amorphous state and in the nanocrystalline state have been investigated. For comparison, u(i)-T curves of the other two kinds of typical soft magnetic alloys also have been measured. it was found that a sharp Hopkinson peak appeared at the Curie point for each amorphous and crystalline alloy but there was no Hopkinson peak for the nanocrystalline alloy at the Curie point of the residual amorphous phase. This phenomenon has been explained in terms of the characteristic temperature dependence of the effective magnetic anisotropy.

The total ribbon voltage of as-quenched and annealed Fe96-xZrxB4 (x=7 or 10) ribbons has been measured as a function of applied de field and drive current frequency. The experimental results show that both samples exist the optimum annealing temperature and optimum frequency at which the relative change in ribbon voltage is strongest, and the sensitivity of the magnetic response of the annealed Fe89Zr7B4 ribbon is two order of magnitude larger than that of the annealed Fe86Zr10B4 ribbon. The effect of magnetic properties and structural characteristics on giant magneto-impedance was discussed.

M-s-T curves and hysteresis loops were investigated for amorphous Fe78Si9B13, (FeNi)(78)(CrSiB)(22), their lap-wound-cores, and their composite ribbons made by two-chamber-crucible technique. The properties of the lap-wound cores of the two kinds of ribbons are similar. For the composite ribbons. the intrinsic properties are the average of the two alloys. Their technological properties, i.e., hysteresis loops, however, are no longer the average of the two alloys. Instead, they show some dramatic changes compared to the lap-wound-cores. Especially, the shape of the hysteresis loop of the composite ribbon cores is largely different from that of lap-wound-cores. The reason for the difference is supposed to be internal stress induced from cooling after annealing.

The microstructure and the stability of Fe73.5Cu1Nb3Si13.5B9 alloy at different stages of phase transformation were investigated through the observation of X-ray diffraction and transmission electron microscopy and the measurement of magnetic aftereffect (MAE). It was found that the dependence of the volume fraction of amorphous phase and the MAE in the samples annealed from 450 to 700 degrees C on the annealing temperature is similar.

Commercial grain oriented silicon steel was cold rolled to thickness from 0.06 to 0.10 mm by cross shear rolling, then annealed in vacuum or a hydrogen atmosphere furnace. Deformation textures of the sheets were researched by ODF method and reverse pole figure quantitative analyses. The results indicate that: in the condition of the cross shear rolling, the deformation texture of roiled sheet is generally similar to that of conventional rolled sheet, however, the texture distribution through the thickness is asymmetrical. With mismatch speed ratio increasing, the amount of Goss texture increases, With reduction ratio increasing, the intensity of gamma-fiber becomes strong.

The influence of alloy elements on de and ac magnetic properties of Fe79M2Si6B11C2(M is V, Mo or Cr) amorphous alloys was investigated. The variation law of the magnetic properties and the loss with the different elements was studied. The results show that the addition of V, Cr or Mo elements reduces the saturation magnetic induction in varying degrees. The addition of V element increases the permeability, decreases the coercivity and drops the loss. The addition of Cr and Mo reduces the permeability, and increases the coercivity.

The magnetic property of soft magnetic metals and alloys depends strongly on the crystallographic orientation. In automated equipment for orientation research. the intensity for drawing up the pole figure is measured in detail. The present research shows that the accurate pole figure can be drawn up without measuring concretely the intensity. For directional Si steel sheet the measuring step may be 4 similar to 5 degrees. In this paper the experimental equation for defocusing correction was derived from the experimental data in different specimens with random orientation.

Perovskite-like bulk La1/3Nd1/3Ca1/3MnO3 is prepared by solid phase reaction method. The temperature dependence of the magnetization and the relationship between CMR effect and sintering have been studied. The CMR is up to 673.9% under 1 T applied magnetic field and 100 K temperature, and that also reaches 93.5% in 0.2 T and 100 K.

For reducing the core loss of grain oriented silicon steel and improving its aging property, a new method, the LLSA by using Sb as the laser surface alloying element, was investigated, and at proper technique conditions rather good result was obtained.

The magnetoresistance effect and magnetic properties in amorphous and nanocrystalline Fe(Cu, Nb)-Si-B ribbons have been investigated. It was observed that the anisotropic magnetoresistance (AMR) of nanocrystalline alloy is much smaller than that of amorphous alloy, indicating that the anisotropy of nanocrystalline alloy becomes smaller after crystallizing. and the smallest AMR is coincident with the excellent soft magnetic characteristics. It is believed that the smaller magnetic crystalline anisotropy is the origin of the excellent soft magnetic characteristics of nanocrystalline alloy.

A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature T-C for ferromagnetic La(FexSi1-x)(13) compounds has been confirmed by applying magnetic field. The Volume change just above T-C for x=0.88 is huge of about 1.5%, which is caused by a large magnetic moment induced by the IEM transition. These compounds have a possibility for practical applications as giant magnetostrictive materials. Pronounced Invar effects bring about a negative thermal expansion below T-C, closely correlated with the negative mode-mode coupling among spin fluctuations.

Structure and magnetostriction of Dy1-xPrxFe2 (0 less than or equal to x less than or equal to 0.5), Dy0.6Pr0.4(Fe1-yTy)(2) (0 less than or equal to y less than or equal to 0.6), and Tb1-zPrz(Fe0.4Co0.6)(2) (0 less than or equal to z less than or equal to 1.0) alloys (T=Co, Ni) have been investigated. It is found that the matrix of the alloys Dy1-xPrxFe2 is a single phase (Dy, Pr)Fe-2 with MgCu2-type structure and the second phase is (Dy, Pr)Fe-3 when x less than or equal to 0.2. The amount of (Dy, Pr)Fe-3 phase increases with increasing Pr content and becomes the main phase when x=0.4. The matrix of Dy1-xPrxFe2 is found to be the (Dy, Pr)(2)Fe-17 phase with Th2Zn17-type structure when x=0.5. It is found that the amount of the cubic Laves phase (Dy, Pr)(Fe, Co)(2) in the Dy0.6Pr0.4(Fe1-yCoy)(2) increases with increasing Co concentration when 0 less than or equal to y less than or equal to 0.6. The substitution of Ni for Fe is nearly not favorable for the formation of the cubic Laves phase (Dy, Pr)(Fe, Ni)(2) in (Dy1-xPrx)Fe-2. The matrix of (Tb1-zPrz)(Fe0.4Co0.6)(2) is a (Tb, Pr)(Fe, Co)(2) phase with the MgCu2-type cubic Laves structure and a second phase of small amount is (Tb, Pr)(Fe, Co)(3) phase when z less than or equal to 0.2, z=0.5 and 1.0. When 0.2

Preparing method and processing of Tb-Dy-Fe alloy samples with [(1) over bar 10] axial orientation as well as their magnetostrictive properties have been studied. It has been found that the magnetostrictive strains of polycrystal samples with [(1) over bar 10] axial orientation can reach (1550 similar to 1900) x 10(-6) in a low magnetic field less than 80 kA/m, which are equal to or somewhat better than that of the polycrystal samples with [11 (2) over bar] axial orientation.

The structure and magnetostriction of R0.5Pr0.5Fex, (R = Dy0.7Tb0.3, 1.10 less than or equal to x less than or equal to 1.85) alloys were investigated. It was found that the matrix of are-melting R0.5Pr0.5Fex, alloys is the (Dy, Tb, Pr) Fe-2 phase with the MgCu2-type cubic structure and the second phase is rare earth-rich phase when x<1.25. In the range of 1.40 less than or equal to x<1.55, the second phase is (Dy, Tb, Pr)Fe-3 and it becomes the main phase when x >1.55. The crystalline structure of mechanically grinding R0.5Pr0.5Fex, alloys is similar to that of the are-melted alloys. The magnetostriction of the alloys increases with increasing Fe content when x less than or equal to 1.25 and decreases when x>1.25.

The structural and magnetostrictive properties of (CexTb1-x)(0.5)Pr0.5Fe2 were investigated. Ce-concentration must exceed x=0.6 in order to obtain the pure Laves phase. The magnetostriction and anisotropy constant increase with the Tb-content in this system. The anisotropy value of PrFe2 is lower than that of isostructural DyFe2. From the X-ray step-scanned data we found that lambda(111) Of PrFe2 is 1310x10(-6). A large increase of magnetostriction can be observed under a small prestress of 6 MPa for Ce0.5Pr0.5Fe2.

The free energy change for the reduction-diffusion reaction which was used to prepare the DyFe2 Dy2O3(s) + 3Ca(g) + 4Fe(s) = 3CaO(s) + 2DyFe(2)(s) intermetallic compound powder was calculated. The reduction-diffusion experiments were carried out at 1073, 1123, 1273 and 1373 K respectively using powders of Dy2O3, iron, and calcium grains as raw materials. XRD and EDX analysis confirmed that DyFe2 was formed by the diffusion of Dy into Fe.

Results on the magneto-optical investigation of near-surface micromagnetic structure (MMS) of Co69Fe4Si12B15 amorphous wires 10 similar to 50 mu m in diameter are presented. The wires were prepared by the rapid solidification technique. The magnetic field H was applied along or perpendicular to the wire length. By scanning the light spot of 1 mu m-diameter along the wire length, distributions of magnetization components (both parallel and perpendicular to the applied magnetic field) and also local hysteresis characteristics of the wires were measured. It was experimentally established that owing to the compressive stresses from quenching coupled with negative magnetostriction of Go-rich amorphous materials, the examined microwires have a circumferential magnetic anisotropy. In consequence, there are the near-surface alternate left- and right-handled circular domains in these samples. The dependencies of the circular domain width on the wire diameter and length were found. It was discovered that in the axial magnetic field local hysteresis loops are unhysteretic. It was proved that in this case the dominant mechanism of the wire magnetization reversal is rotation of local magnetization vectors in circular domains.

GMR effect of multilayers of bcc-Fe(M)(M=Co, Ni) alloy and Cu layers has been investigated. The maximum MR ratio is found at 1.1 nm Fe(Co) and 1.3 similar to 1.4 nm Cu layer thickness in [Fe(Co)/Cu], and at 1.6 nm Fe(Ni) and 1.4 nm Cu layer thickness in [Fe(Ni)/Cu]. Under the optimum annealing condition, the MR ratio increases up to 50% and 38% for Fe(Co) and Fe(Ni) systems, respectively. The origin of the increase of GMR is discussed, taking the progress of preferred orientation of Fe(Co)[100] or Fe(Ni)[100] by annealing into account.

The Fe3O4/Fe/Fe3O4 (MIM) tri-layer films (200 nm/12 similar to 93 nm/200 nm) were prepared on Si(100) by DC-magnetron reactive-sputtering followed by air- or vacuum-annealing at 280 similar to 400 degrees C for 1.5 h, respectively. Magnetic properties and phases under different sandwich and annealing conditions were studied. In MIM structure, the incorporation of the interlayer iron does increase the magnetization measured under 8 kOe (M-8K), but reduce coercivity (H-c). The H-c of as-deposited films decreases from 354 Oe to 74 Oe, while M-8K increases from 254 to 392 emu/cc. By annealing in air, the whole MIM tri-layer film becomes gamma-Fe2O3 H-c is about 550 Oe and M-8K is around 250 emu/cc. The coercivity mechanism of as-deposited and annealed MIM trilayer films belongs to domain-wall pinning type. delta M plots show that when the interlayer Fe thickness is 12 nm, the Fe and Fe3O4 layers are decoupled in the as-deposited and annealed states, while it is coupled in the as deposited state when the Fe thickness increases to 23 nm. Vacuum annealing of the MIM films leads to increase in both coercivity and magnetization, and to enhance the exchange coupling between layers.

The magnetic and structural properties in Co/Cu/Co sandwiches with Ni and Cr buffer layers were investigated. It was found that the coercivity in Ni layer buffered samples decreases with increasing Ni layer thickness, while that in Cr layer buffered ones increases with increasing Cr layer thickness, leading to a large difference in field sensitivity of their giant magnetoresistance (GMR) properties. X-ray diffraction and high resolution transmission electron microscope images exhibited that there is a strong fee (111) texture in the samples with Ni buffer layer. But there are only randomly oriented polycrystalline grains in Cr buffered sandwiches. According to atomic force microscope topography, the surface roughness of Cr buffered sandwiches is smaller than that of Ni buffered ones. It is demonstrated that buffer layer influences both magnetic and structural properties in Co/Cu/Co sandwiches as well as their GMR characteristics.

The transverse permeability ratio (TPR) and longitudinal permeability ratio (LPR) as a function of an external field of mumetal films have been investigated in conjunction with the magnetic properties. The mumetal films were prepared by the R.F.magnetron sputtering method in Ar atmosphere. The LPR curve shows the single peak pattern, and the TPR curve shows the double peak pattern indicating the existence of the magnetic anisotropy effect. The magnitude of the incremental permeability are strongly depended on the magnetic softness. The large changes of LPR and TPR in low external fields can be useful for the evaluation of the magnetic softness.

Sm22Co78/Fe65Co35/Sm22Co78/Fe65Co35 multilayer films were prepared by magnetron sputtering. The temperature dependence of coercivity (H-c), remanence (M-r) and reduced remanence (M-r/M-s) has been measured. The coercivity decreases with increasing of temperature. The remanence decreases with increasing the temperature from 26 to 100 degrees C, and then increases with continuously increasing the temperature from 100 to 150 degrees C. The reduced remanence increases with increasing the temperature.

Three kinds of oxide underlayers, namely SiO2, ZnO and Al2O3, were deposited prior to the sputtering of Sr-ferrite films, respectively, in order to induce the optimum grain morphology and the texture of the films. A Sr-ferrite film with an easy axis in-plane orientation was induced by SiO2 underlayer. In contrast, it prefers to be perpendicular to film plane for the cases of ZnO and Al2O3 underlayers. The optimum magnetic properties of the former film along film plane are: 4 pi M-r=1.7 kG, H-i(c)=5.35 kOe, and S-q=0.59, which are mainly dominated by the exchange coupling effect. determined by Wohlfarth's remanence analysis. among grains. White those for the films with an easy axis perpendicular to film plane can be as high as 4 pi M-r=3.72 kG, H-i(c)=6.42 kOe, and S-q=0.82, which are mainly dominated by the magnetostatic interaction among grains.

Sensitive materials mainly composed of ZnO and their multi-functional properties were investigated. The temperature extent of linear resistance, non-linear deviation and endurance ability of surge energy were further discussed. The effect of Mg2+, Al3+ and Si4+: which could be solid solutioned in ZnO grain and the function of Y3+ ion segregated out in grain boundary were studied as well. The function of Ti was analyzed emphatically.

The principle and performance of a fiber-optic Faraday-effect magnetic-field sensor based on an yttrium iron garnet (YIG) and two flux concentrations are described. A single polarization-maintaining optical fiber links the sensor head to the source and detection system, in which the technique of phase shift cancellation is used to cancel the phase shift that accumulate in the optical fiber. Flux concentrators were exploited to enhance the YIG crystal magneto-optic sensitivity. The sensor system exhibited a noise-equivalent field of 8 pT/root Hz and a 3 dB bandwidth of similar to 10 MHz.

By measuring frequency dependence of photoinduced double peaks of disaccommodation, DA as a function of temperature was observed at very low frequency: 0.07 similar to 0.30 kHz, in a single crystal of yttrium iron garnet. YIG with small amounts of Ca: 0.001, while only single peak existed at the higher frequency 0.5 kHz. The behavior is explained based on theoretical approach on a domain wall dynamics.

Thermal sensitive MnZn ferrite is a kind of soft magnetic ferrite material with lower Curie temperature (T-C) and can be used to make many kinds of magnetic thermal sensitive sensors with high sensitivity. In this paper, the relation between the composition of thermal sensitive ferrite and T-C was studied. It was found that T-C changes linearly with ZnO extent when the content of Fe2O3 is fixed. Based on lots of experiments, an experimential formula to determine T-C was given out.

This paper shows that it is easier to form intelligent ceramics than other materials. Self-adaptive factors and relevant function mechanisms, which determine the formation of intelligent ceramics, are studied and data from the design of the PLZT with complex functions are presented.

Due to continued growth in key markets, a broadening of application base and performance improvements, the market demands of NdFeB magnet increased steadily in 1998, and the global output of sintered NdFeB magnet exceeded 10,000 t, in spite of the economic recession in Asia. In 1998 China produced 3,850 t sintered NdFeB block magnet, with an annual growth rate of +22% over the output in 1997.

Hard disk drives became the major information storage devices, supported by rapidly advancing magnetic recording technology. In this paper, several technical challenges to overcome the superparamagnetic limit are explained. The longitudinal magnetic recording shall be extended more than 100 Gb/in(2), by adopting new media structure to stabilize the magnetization decay.

The dependence of transformer performance on the material properties was investigated using two laboratory-processed 0.23 mm thick grain-oriented electrical steers domain-refined with electrolytically etched grooves having different magnetic properties. The iron loss at 1.7 T, 50 Hz and the flux density at 800 A/m of material A were 0.73 W/kg and 1.89 T, respectively, and those of material B, 0.83 W/kg and 1.88 T. Model stacked and wound transformer core experiments using the tested materials exhibited performance well reflecting the material characteristics. In a three-phase stacked core with step-lap joints excited to 1.7 T, 50 Hz, the core loss, the exciting current and the noise level were 0.86 W/kg, 0.74 A and 52 dB, respectively, with material A, and 0.97 W/kg, 1.0 A and 54 dB with material B. The building factors for the core losses of the two materials were almost the same in both core configurations. The effect of higher harmonics on transformer performance was also investigated.

Magnetic stripe is one of the major applications of magnetic materials. As a key component of the present card technologies magnetic stripes play reliable components for electronic data interchange in worldwide electronic payment systems such as financial cards, transit tickets and phone cards, etc. Magnetic stripes are available in various coercivity materials, widths, lengths, structures and colors with each types of transferable, lamination and pressure sensitive magnetic tapes of Deuton-M. Manufacturing process, structure and characteristics of Deuton-M magnetic tape and sheet are described.

This paper describes field modeling and thermal modeling for magnetizing fixture. As the detailed characteristics of magnetizing fixture can be obtained, the efficient design of magnetizer which produce desired magnet will be possible using our modeling. For field modeling finite-element analysis is used as part of the design and analysis process for magnetizing fixture. The thermal modeling method of magnetizing fixture resistor uses multi-lumped model with equivalent thermal resistance and thermal capacitance.

The extraordinary progress in magnetic peripheral storage systems has been fueled by the advancements in heads (MR, GMR, spin valves) and in very high coercivity, low remanence-thickness product (M(r)t) media. These advancements are imposing new performance requirements on the magnetometers (VSMs) used to characterize these materials. At the same time, they have introduced a new paradigm for in-process (nondestructive, robotic) magnetic metrology toots to assure the stringent product uniformity requirements. In this paper, we discuss the recent advancements in magnetometry for characterizing state-of-the-art media and heads, as well as other magnetic materials.

To obtain microstructure of magnetic devices, the thin film inductors were fabricated by the process such as thin film manufacturing, photolithography and wet etching. The frequency characteristics of these devices are measured at high frequency range. When the inductor sizes of the spiral and the meander type are same, the inductance and the quality factor of the spiral type inductor are larger than those of the meander type inductor, but the driving frequency of the spiral type inductor is fewer than that of the meander type inductor.

The performance of a 3-phase 6-pole 400 W inverter-drive induction motor was investigated using a variety of non-oriented electrical steels for stator core at PWM inverter fundamental wave frequencies of 30 to 300 Hz. There existed an optimum Si content of the material depending on the tooth flux density. Both reduction of material thickness and stress-relief annealing of the stator core improved the motor efficiency. The influence of Si content on the efficiency was small at lower PWM frequencies, while at higher frequencies the motor efficiency increased with increasing Si content. The Cu loss W-c increased and the Fe loss W-i counteractively decreased with increasing Si content at lower frequencies, while at higher frequencies W-i had dominant effect on the efficiency. Newly developed materials RMA, having lower Fe tosses after stress-relief annealing and higher flux densities with lower Si contents, showed motor efficiencies superior to conventional JIS grade materials with comparable Fe losses.

We present a theoretic model to calculate skin depths and eddy-current power losses for a magnetic position sensor. Eddy-current, arised from the operation of an alternating-current excitation, induces secondary currents and fields between magnetic material and magnetic position sensor. In this paper, a magnetic position sensor system is simplified to be an outer-winding toil along the axial direction of a low carbon steel bar. The analytical model is derived from basic field and circuit theory considering a linear approximation for a nonlinear permeability. Thus the skin depths and eddy-current power losses from the model in eddy-current modeling techniques at various frequencies of an excited current source can be calculated. The proposed configuration is capable of predicting the skin depths and eddy-current power losses for a magnetic position sensor and has a consistence with experiments.

The axial magnetic force, induced by the complicated flux linkage distribution from rotor magnet and stator slotted, is constructed by different relative heights and calculated by 3D finite element method (FEM) to analyze the dynamic characteristics for a DVD spindle motor. The axial magnetic force is designed to provide an axial stiffness and govern the natural frequency of the dynamic performance. According to the simulation results and experimental measurements, the dynamic behaviors are significantly improved with a variation of relative height of rotor magnet and stator slotted on a DVD spindle motor.

A portable microcomputer-controlled inspection system has been developed for detection of magnetic properties of soft magnetic materials. It incorporates custom designed software for control of the magnetic field during operation such as demagnetization, field sweeping, and for data logging and analysis. Results are recorded using a 12-bit analog to digital converter and are then stored on disk. The magnetic hysteresis loop and Barkhausen noise data can be converted into important magnetic parameters:, coecivity, remanence, and hysteresis loss, Barkhausen amplitude, and Barkhausen noise energy. This system incorporated with the magnetostriction, and magnetoacoustic emission, is then related with the nondestructive detection of material degradation.

A single phase brushless spindle motor with innovative design has been developed for application in a DVD drive. The methods used to reduce the cogging torque and to improve the dynamic performance of this new design motor are proposed in this paper. The single phase brushless spindle motor is usually applied for cooling fan, pump and blower before the performance is improved by the reengineering process. The stator configuration and the drive circuit have been remodeled in order to meet the requirements of the spindle motor used in the DVD applications.