• Journal of the Korean Magnetics Society
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• v.9 no.5
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• pp.251-255
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• 1999

NiFe(60 $\AA$)/Co(0$\AA$$\leq$x$\AA$$\leq$15$\AA$)/Cu(60$\AA$)/Co(30$\AA$) spin valve thin films were prepared on 4$^{\circ}$ tilt-cut Si(111) substrates with a 50 $\AA$ thick Cu underlayer without applying any external magnetic field during the deposition, and the effects of inserted ultrathin Co layer on magnetic anisotropy and GMR properties of the NiFe(60 $\AA$)/Cu(60$\AA$)/Co(30$\AA$) spin valves were investigated. As the ultrathin Co layer was inserted into the NiFe/Cu interface of the spin valves, GMR ratio was increased from about 1.5% to 3.5%, and the easy axis of NiFe(60 $\AA$) layer was rotated by 90$^{\circ}$. Accordingly, it was aligned along the same direction with the easy axis of Co(30 $\AA$)layer. Therefore, squared R-H curves was obtained in the spin valves, which is favorable properties for the digital GMR devices such as MRAM. In order to investigate the change of magnetic anisotropy of NiFe layer of the spin valves in more details,XRD measurement was performed using NiFe(500 $\AA$) and NiFe(500 $\AA$)/Co(10 $\AA$) thin films on the same templates. Strong (220) NiFe peak was observed in both films regardless of the inserted Co layer, so it was thought that the variation of magnetic anisotropy of NiFe layer is from the interface effect, the change of interface from NiFe/Cu to NiFe/Co, rather than the volume effect such as the change of magnetocrystalline effect.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1140-1142
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• 1993

It has been prepared by a coprecipitation method for Ferroxplana $Ni_2Y\;(Ba_2Ni_2Fe_{12}O_{22}$ magnetic particles, which is one of the Hexagonal ferrite. The coprecipitates were synthesized by adding aqueous solution of $BaCl_2{\cdot}2H_2O,\;NiCl_2{\cdot}6H_2O\;and\;FeCl_2{\cdot}4H_2O$ (of which the mole ratio is $Ba^{2+}:Ni^{2+}:Fe^{2+}$=1:1:6) to a mixture of NaOH and $Na_2CO_3$ solution. The shape of Ferroxplana $Ni_2Y$ magnetic particles obtained at the calcined temperature 1,100($^{\circ}C$) was hexagonal plate-like, average particle size was 2(${\mu}m$), and aspect ratio was more than 7.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.80-80
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• 2004

• Journal of the Korean Magnetics Society
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• v.7 no.5
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• pp.265-273
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• 1997

The MR ratios and the exchange biasing field and interlayer coupling field were investigated in $Ni_{91}Fe_{19}/Co_{90}Fe_{10}/Cu/Co_{90}Fe_{10}/NiO$ spin-valve sandwiches grown on antiferromagnetic NiO films as a function of the NiO thickness, the thickness of Cu and pinning layer $Co_{90}Fe_{10}$. The spin-valve sandwiches were deposited on the Corning glass 7059 by means of the 3-gun dc and 1-gun rf magnetron sputtering at a 5 mtorrpartial Ar pressure and room temperature. The deposition field was 50 Oe. The MR curve was measured by the four-terminal method with applied magnetic soft bilayer [NiFe/CoFe] (90$\AA$) decreased dramatically to less than 10 Oe when the NiFe/CoFe bilayer used an NiFe bilayer thicker that 20$\AA$. So NiFe layer improved the softmagnetic properties in the NiFe/CoFe bilayer. The GMR ratio and the magnetic field sensitivity of the spin-valve film $Ni_{91}Fe_{19}(40{\AA})/Co_{90}Fe_{10}(50{\AA}) /Cu(30{\AA})/Co_{90}Fe_{10}(35{\AA})/NiO(800{\AA})$ was 6.3% and about 0.5 (%/Oe), respectively. The MR ratio had 5.3% below an annealing temperature of 20$0^{\circ}C$ which slowly decreased to 3% above 30$0^{\circ}C$. The large blocking temperature of the spin-valve film was taken (as being) due to the good stability of the NiO films. Thus, the spin-valve films with a free NiFe/CoFe layer clearly had a high large GMR output and showed a effective magnetic field sensitivity for a suitable spin-valve head material.

• Journal of Magnetics
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• v.6 no.4
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• pp.145-147
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• 2001

The effect of interface roughness between [Ni/Mn] superlattice and pinned NiFe layer on magnetoresistance (MR) of [Ni/Mn] superlattice-based spin valve films was investigated. Antiferromagnetic phase structure and interface roughness of [Ni/Mn] superlattice spin valve films were compared in the as-deposited and the annealed samples at 240$\^{C}$, respectively. Surface morphology of spin valves was substantially flattened due to the formation of the antiferromatic NiMn phase. In case of Co insertion between Cu and NiFe, the interlace roughness and MR ratio in the annealed [NiMn] superlattice and pinned NiFe/Co layer increased more than those in the annealed [Ni/Mn] superlattice and pinned NiFe layers respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.144-148
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• 1993

This paper is a study on electromagnetic wave absorption properties for the composition ratio of Ni-Zn-Fe$_2$O$_4$. Li-Zn-Fe$_2$O$_4$was composed of Fe$_2$O$_3$ 48∼51mo1%, LiO 18 ∼22mo1%, ZnO 34∼27mo1%. and sintering was carried out at 1200$^{\circ}C$. Through the experiments, the resonance phenomenon occured at low frequence range for high permeability, and vice versa. Specialy, In the case of Fe$_2$O$_3$49mol%, NiO 20mo1%, ZnO 3lmol% ,and the matching thickness was 10mm , the absorbing bandwith was 0.35 ∼0.95GHz. Also, In the case of Fe$_2$O$_3$51mo1%. NiO 22mo1%, ZnO 27mol%, we could get the absorbing bandwith of 0.45∼1.2GHz when the matching thickness was 6mm. Therefore. it is proved that electromagnetic wave absorbers with the above bandwidth range can be fabricated successful1y.

• Journal of the Korean Ceramic Society
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• v.28 no.4
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• pp.305-314
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• 1991

This study was conducted to research the formation and the color development of NiO-ZnO-Fe2O3-TiO2-SnO2 system for the purpose of synthesizing the spinel pigments which are stable at high temperature. After preparing ZnO-Fe2O3 as a basic composition, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.Fe2O3 system, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.TiO2 system, and {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.SnO2 system were prepared with {{{{ chi }}=0, 0.2, 0.5, 0.7, 1 mole ratio respectively. The manufacturing was carried out at 128$0^{\circ}C$ for 30 minutes. The reflectance measurement and the X-ray analysis of these specimens were carried out and the results were summarized as follows. 1. In the specimens which included NiO, it was difficult for the spinel structure to be formed. 2. As increasing the contents of NiO and Fe2O3, all the groups which were yellow or green colored changed to brown. 3. NiO-ZnO-Fe2O3 system and NiO-ZnO-TiO2 system formed the spinel structure and the illmenite structure appeared in NiO-TiO2 system.

• Resources Recycling
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• v.16 no.6
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• pp.3-9
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• 2007

Although the ferrous material was separated by the magnetic separation before the incineration process, the municipal solid waste incineration bottom ash generated during incinerator in metropolitan area consists of many iron products which account for about $3{\sim}11%$ as well as ceramics and glasses. The formation of $NiFe_2O_4$ and $FeCr_2O_4$ with a $Fe_3O_4-Fe_2O_3$ (similar to pure Fe) on the surface of iron product was found during air-annealing in the incinerator at $1000^{\circ}C$, because Ni and Cr has a chemical attraction about iron is using to coat with Ni and Cr metals for poish or to prevent corrosion. Therefore, Fe-Ni Cr oxide can be formed on durface of the iron product and it can be separated from bottom ash through the magnetic separation. So, in this study, the separation ratio of heavy metals as magnetic separation and mineralogical formation of Fe-ion(heavy metal) in ferrous metals corroded were investigated. As the result, the separation ratio of Ni and Cr based on particle sizes accounted for about $45{\sim}50%$, and Cu and Pb accounted for below 20%. Also, the leaching concentration of Ni and Cr in bottom ash separated by magnetic separation was lower than that in fresh bottom ash.

• Journal of the Korean Magnetics Society
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• v.3 no.4
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• pp.277-283
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• 1993

The temperature dependence of DC magnetic susceptibilities of three austenitic Fe-Cr-Ni stainless alloys were measured in the temperature range of 4.2 and 300 K. Two alloys support a general magnetic description of austen-itic stsinless steels in terms of a two-magnetic-phase (spin glass + superparamagnetic cluster) model and one alloy shows magnetic double transition phenomena. Also this study shows that incressing the Ni/Cr ratio in Fe-Cr-Ni alloys causes a increase of the DC susceptibility peak value and a decrease of the magnetic transition temperature.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.5
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• pp.225-232
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• 2013

The influence of aging treatment, addition elements and rolling reduction ratio on the microstructure, mechanical, electrical and bendability properties of Cu-Ni-Si-P-x (x = Fe, Sn, Zn) alloys for connector material application was investigated. SEM/EDS analysis exhibited that Ni2-Si precipitates with a size of 20~100 nm were distributed in grains. Fe, Sn, Zn elemnets in Cu-Ni-Si-P alloy imporved the mechanical strength but it was not favor in increasing of electrical conductivity. As higher final rolling reduction ratio, the strength and electrical conductivity is increased after aging treatment, but it indicated excellent bendability. Especially, Cu-2Ni-0.4Si-0.5Sn-0.1Fe-0.03P alloy show the tensile strength value of 700MPa and the electrical conductivity was observed to reach a maximum of 40%IACS. It is optimal for lead frame and connector.