• Title/Summary/Keyword: Fe-N/C

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Exchange Bias Perpendicular Magnetic Anisotropy and Thermal Stability of (Pd/Co)N/FeMn Multilayer ((Pd/Co)N/FeMn 다층막에서의 교환바이어스 수직자기이방성과 열적안정성)

  • Joo, Ho-Wan;An, Jin-Hee;Kim, Bo-Keun;Kim, Sun-Wook;Lee, Kee-Am;Lee, Sang-Suk;Hwang, Do-Geun
    • Journal of the Korean Magnetics Society
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    • v.14 no.4
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    • pp.127-130
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    • 2004
  • Magnetic properties and thermal stability by exchange biased perpendicular magnetic anisotropy in (Pd/Co)$_{N}$FeMn multilayer deposited by do magnetron sputtering system are investigated. We measured the perpendicular magnetization curves of (Pd(0.8nm)/Co(0.8nm)$_{5}$FeMn multilayer as function of FeMn thickness and annealing temperature. As FeMn thickness increases from 0 to 21nm, the perpendicular exchange bias(Hex) obtained 127 Oe at FeMn thickness 15nm. As the annealing temperature increases to 24$0^{\circ}C$, the E$_{ex}$ increased from 115 Oe to 190 Oe and disappeared exchange biased perpendicular magnetic anisotropy effect at 33$0^{\circ}C$.

Magnetic Properties of FeZrN/$SiO_2$ Soft Magnetic Multilayer Thin Films (FeZrN/$SiO_2$ 연자성 다층 박막의 자기적 성질)

  • Kim, Taek-Su;Kim, Jong-O
    • Korean Journal of Materials Research
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    • v.6 no.11
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    • pp.1061-1066
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    • 1996
  • RF magnetron reactive sputtering법으로 Fe75.5Zr8.3N16.2/SiO2(250$\AA$) 다층 박막을 FeZrN의 두께를 변화시키면서 제조하고, 제조된 박막을 진공 열처리하여 열처리 온도에 따른 포화자화, 보자력, 고주파에서의 투자율 그리고 열적 안정성을 조사하였다. Fe75.5Zr8.3N16.2/SiO2(250$\AA$) 다층박막은 FeZrN의 두께가 800$\AA$이상일 때 좋은 연자성을 나타내었다. Fe75.5Zr8.3N16.2/SiO2(250$\AA$)다층 박막을 45$0^{\circ}C$로 열처리 했을 때 포화자속밀도(1.08 T), 보자력 0.41 Oe, 1 MHz에서의 실효 투자율은 3000이상의 연자성을 나타내었다. 그 이유는 X-선 회절 분석 결과 열처리에 의해서 ZrN 미결정이 석출하여 $\alpha$-Fe 결정 성장이 억제되어 우수한 연자기적 성질이 나타난다고 판단된다. 이때 $\alpha$-Fe 입자 크기는 40-50$\AA$, ZrN의 입자 크기는 10-15$\AA$이다. 그리고 실효 투자율의 주파수 의존성에서 단층막에서는 5 MHz 이상에서 실효 투자율이 급격히 감소하는 경향을 보였으나, 다층막에서는 40MHz까지 실효 투자율이 1600이 되어 고주파에서의 연자성이 개선되었다.

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Formation Reaction of Mn-Zn Ferrite by Wet Process (습식합성에 의한 Mn-Zn Ferrite의 생성반응에 관한 연구)

  • 이경희;이병하;허원도;황우연
    • Journal of the Korean Ceramic Society
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    • v.30 no.1
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    • pp.25-33
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    • 1993
  • Formation reaction of Mn-Zn ferrite depending on various synthetic conditions of wet process was investigated using FeCl2.nH2O(n≒4), MnCl2.4H2O, ZnCl2 as starting materials. A stable intermediate precipitate was formed by the addition of H2O2. And the precipitate was hard to transform to spinel phase of Mn-Zn Fe2O4. Single phase of Mn-Zn Fe2O4 spinel was obtained above 8$0^{\circ}C$ reaction temperature. The powder had spherical particle shape and 0.02~0.05${\mu}{\textrm}{m}$ particle size. Fe(OH)2 solid solution, -FeO(OH) solid solution, -FeOOH, Mn-Zn Fe2O4 spinel were formed with air flow rate 180$\ell$/hr. However, single phase of Mn-Zn Fe2O4 spinel with cubic particle shape and 0.1~0.2${\mu}{\textrm}{m}$ particle size was formed with synthetic conditions of 8$0^{\circ}C$ and 90 munutes. The particle shape of the -FeOOH was needle-like.

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Synthesis and magnetic properties of $Fe_3C$ fine particles ($Fe_3C$ 미립자의 제조와 자기적 특성)

  • Seo, Il-Gwon;Lee, Seung-Won;Gwon, Hyeok-Mu
    • Korean Journal of Materials Research
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    • v.3 no.6
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    • pp.652-660
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    • 1993
  • It was investigated to obtain the relationship between magnetic properties and conditions of forming $Fe_{3}C$ single phase from acicular goethite by heat treatment under the atmosphere of CO and $N_{2}$ mixed gas. X-ray analyses, TEM and VSM measurements were imployed for the characteristics of the carbide. Acicular goethite was sinthesized under proper process parameters. $Fe_{3}C$ single phase was obtained above $550^{\circ}C$, 60min. and $Fe_{5}C_2$ was formed with $Fe_{3}C$ below that temperature. The soturation magnetization of $Fe_{3}C$ single phase was about 100emu/g regardless of the reaction temperature. The coersive force and the ratio of Mr/Ms decreased respectively from 780 to 400 Oe. and from 0.35 to 0.13 with increasing reaction temperature.

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Chiral [Iminophosphoranyl]ferrocenes: Synthesis, Coordination Chemistry, and Catalytic Application

  • Co, Thanh Thien;Shim, Sang-Chul;Cho, Chan-Sik;Kim, Dong-Uk;Kim, Tae-Jeong
    • Bulletin of the Korean Chemical Society
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    • v.26 no.9
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    • pp.1359-1365
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    • 2005
  • A series of new chiral [iminophosphoranyl]ferrocenes, {${\eta}^5-C_5H_4-(PPh_2=N-2,6-R_2-C_6H_3)$}Fe{${\eta}^5-C_5H_3-1-PPh^2-2-CH(Me)NMe_2$} (1: R = Me, $^iPr$), {${\eta}^5{-C_5H_4-(PPh_2=N-2,6-R_2}^1-C_6H_3)$}Fe{${\eta}^5-C_5H_3-1-(PPh_2=N-2,6-R_2-C_6H_3)-2-CH(Me)R_2$} (2: $R^1\;=\;Me,\;^iPr;\;R^2\;=\;NMe_2$, OMe), and $({\eta}^5-C_5H_5)Fe${${\eta}^5-C_5H_4-1-PR_2-2-CH(Me)N=PPh_3$} (3:R = Ph, $C_6H_{11}$) have been prepared from the reaction of [1,1'-diphenylphosphino-2-(N,N-dimethylamino) ethyl]ferrocene with arylazides (1 & 2) and the reaction of phosphine dichlorides ($R_3PCl_{2}$) with [1,1'-diphenylphosphino-2-aminoethyl]ferrocene (3), respectively. They form palladium complexes of the type $[Pd(C_3H_5)(L)]BF_4$ (4-6: L = 1-3), where the ligand (L) adopts an ${\eta}^2-N,N\;(2)\;or\;{\eta}^2$-P,N (3) as expected. In the case of 1, a potential terdentate, an ${\eta}^2$-P,N mode is realized with the exclusion of the –=NAr group from the coordination sphere. Complexes 4-6 were employed as catalysts for allylic alkylation of 1,3-diphenylallyl acetate leading to an almost stoichiometric product yield with modest enantiomeric excess (up to 74% ee). Rh(I)-complexes incorporating 1-3 were also prepared in situ for allylic alkylation of cinnamyl acetate as a probe for both regio- and enantioselectivities of the reaction. The reaction exhibited high regiocontrol in favor of a linear achiral isomer regardless of the ligand employed.

Oxidation of CrAlMgSiN thin films between 600 and 900℃ in air (CrAlMgSiN 박막의 600-900℃에서의 대기중 산화)

  • Won, Seong-Bin;Xu, Chunyu;Hwang, Yeon-Sang;Lee, Dong-Bok
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2013.05a
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    • pp.112-113
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    • 2013
  • Thin CrAlMgSiN films, whose composition were 30.6Cr-11.1Al-7.3Mg-1.2Si-49.8N (at.%), were deposited on steel substrates in a cathodic arc plasma deposition system. They consisted of alternating crystalline Cr-N and AlMgSiN nanolayers. After oxidation at $800^{\circ}C$ for 200 h in air, a thin oxide layer formed by outward diffusion of Cr, Mg, Al, Fe, and N, and inward diffusion of O ions. Silicon ions were relatively immobile at $800^{\circ}C$. After oxidation at $900^{\circ}C$ for 10 h in air, a thin $Cr_2O_3$ layer containing dissolved ions of Al, Mg, Si, and Fe formed. Silicon ions became mobile at $900^{\circ}C$. After oxidation at $900^{\circ}C$ for 50 h in air, a thin $SiO_2-rich$ layer formed underneath the thin $Cr_2O_3$ layer. The film displayed good oxidation resistance. The main factor that decreased the oxidation resistance of the film was the outward diffusion and subsequent oxidation of Fe at the sample surface, particularly along the coated sample edge.

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Mössbauer Studied of Multiferroic Bi2/3La1/3FeO3 Nanoparticles (Multiferroic Bi2/3La1/3FeO3 나노입자의 Mössbauer 연구)

  • Lee, Seung-Wha
    • Journal of the Korean Magnetics Society
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    • v.16 no.1
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    • pp.28-33
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    • 2006
  • La substituted perovskite $BiFeO_3$ have been prepared by a sol-gel method. Magnetic and structural properties of the powders were characterized with Mossbauer spectroscopy, XRD, SEM, and TG-DTA. The crystal structure is found to be a rhombohedrally distorted perovskite structure with the lattice constant $\alpha=3.985{\AA}\;and\;\alpha=89.5^{\circ}.\;Bi_{2/3}La_{1/3}FeO_3$ powders that were annealed at and above $600^{\circ}C$ have a single-phase perovskite structure. However, powders annealed at $900^{\circ}C$ have a typical perovskite structure with small amount of $Bi_2O_3$ phase. The Neel temperature of $Bi_{2/3}La_{1/3}FeO_3$ is found to be $680\pm3K$. The isomer shift value at room temperature is found to be 0.27 mm/s relative to the Fe metal, which is consistent with high-spin $Fe^{3+}$ charge states. Debye temperature far$Bi_{2/3}La_{1/3}FeO_3$ is found to be $305\pm5K$. The average hyperfine field $H_{hf}(T)$ of the $Bi_{2/3}La_{1/3}FeO_3$, shows a temperature dependence of $[H_{hf}(T)-H_{hf}(0)]/H_{hf}(0)=-0.42(T/T_N)^{3/2}-0.13(T/T_N)^{5/2}$ for $T/T_N<0.7$ indicative of spin-wave excitation.

Preparation of Hard Magnetic $Sm_2Fe_{17}N_x$ Compound by Mechanical Alloying (기계적 합금화법에 의한 영구자석용 $Sm_2Fe_{17}N_x$ 화합물의 제조)

  • 이충효;김명근;석명진;김지순;윤석길;권영순
    • Journal of Powder Materials
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    • v.8 no.1
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    • pp.55-60
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    • 2001
  • Mechanical alloying technique was applied to prepare hard magnetic $Sm_2Fe_{17}N_x$ compound powders. Staring from pure Fe and Sm powders, the formation process of hard magnetic $Sm_2Fe_{17}N_x$ phase by mechanical alloying and subsequent solid state reaction was studied. As milled powders were found to consist of Sm-Fe amorphous and $\alpha$-Fe phases in all compositions of $Sm_xFe_{100-x}$(x = 11, 13, 15, 17). The effects of starting composition on the formation of $Sm_2Fe_{17}$ intermetallic compound was investigated by heat treatment of mechanically-alloyed powders. When Sm content was 15 at.%, heat-treated powders consisted of nearly $Sm_2Fe_{17}$ single phase. For preparation of hard magnetic $Sm_2Fe_{17}N_x$ powders, additional nitriding treatment was performed under $N_2$ gas flow at 45$0^{\circ}C$. The increase in the coercivity and remanence was proportional to the nitrogen content which increased drastically at first and then increased gradually as the nitriding time was extended to 3 hours.

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Study on the Origins of Surface Cracks at Room Temperature in Fe-Cr-Al Alloy Billets (Fe-Cr-Al계 합금 빌렛의 상온 표면균열 원인에 관한 연구)

  • Kim S. W;Park J. H;Kim I. B.
    • Korean Journal of Materials Research
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    • v.14 no.1
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    • pp.19-27
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    • 2004
  • Metallurgical and mechanical experiments were performed to explain unexpected surface cracks encountered in fabricating ground rolled-billet of Fe-Cr-Al alloys at room temperature. The toughness of these alloys containing between 220 and 236 ppm (C+N) has been assessed using notched-bar impact tests. According to our results, with a larger grain size, a higher interstitial content of (C+N) or a smaller size of precipitates, ductile to brittle temperature(DBTT) increased and absorbed energy decreased at room temperature. These results suggest that the surface cracks at room temperature stem from a poor resistance to brittle fracture, due to dislocation movement by the finely dispersed carbides within grains under the condition of higher (C+N) content.

Characteristics of polycrystalline AlN thin films deposited on 3C-SiC buffer layers for M/NEMS applications (3C-SiC 버퍼층위에 증착된 M/NEMS용 다결정 AlN 박막의 특성)

  • Chung, Gwiy-Sang;Lee, Tae-Won
    • Journal of Sensor Science and Technology
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    • v.16 no.6
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    • pp.462-466
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    • 2007
  • Aluminum nitride (AlN) thin films were deposited on Si substrates by using polycrystalline (poly) 3C-SiC buffer layers, in which the AlN film was grown by pulsed reactive magnetron sputtering. Characteristics of grown AlN films were investigated experimentally by means of FE-SEM, X-ray diffraction, and FT-IR, respectively. The columnar structure of AlN thin films was observed by FE-SEM. X-ray diffraction pattern proved that the grown AlN film on 3C-SiC layers had highly (002) orientation with low value of FWHM (${\Theta}=1.3^{\circ}$) in the rocking curve around (002) reflections. These results were shown that almost free residual stress existed in the grown AlN film on 3C-SiC buffer layers from the infrared absorbance spectrum. Therefore, the presented results showed that AlN thin films grown on 3C-SiC buffer layers can be used for various piezoelectric fields and M/NEMS applications.