• 한국자기학회지
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• 제14권4호
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• pp.127-130
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• 2004

본 연구는 (pd/Co)$_{N}$FeMn 구조의 다층박막을 dc 마그네트론 스퍼터링 시스템으로 증착하여 교환결합된 수직이방성에 대한 자기적 특성과 열적안정성을 조사하였다. 반강자성 FeMn 두께를 0-2lnm에서 변화시키면서 측정한 결과 Ta(1.9 nm)/(Pd(0.8nm)/Co(0.8nm)$_{5}$Mn(15nm)/Ta(1.9nm)에서 127 Oe교환바이어스세기(exchange biasing field: H$_{ex}$)를 얻었다. 그리고 이 구조에서 열적 안정성을 조사하기 위하여 온도 변화에 따른 H$_{ex}$변화를 확인한 결과, 24$0^{\circ}C$까지는 H$_{ex}$가 115 Oe에서 195 Oe까지 증가하였고, 그 이후 33$0^{\circ}C$에서 교환 결합된 수직자기이방성 곡선이 사라지는 것을 관찰하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.267-270
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• 2003

We have studied the interfacial diffusion phenomena and the role of ${\alpha}-Al_2O_3$ buffer layer as a diffusion barrier in the $Ba-ferrite/SiO_2$ magnetic thin films for high-density recording media. In the interface of amorphous Ba-ferrite ($1900-{\AA}-thick)/SiO_2$ thin film during annealing, the interfacial diffusion started to occur at ${\sim}700^{\circ}C$. As the annealing temperature increased up to $800^{\circ}C$, the interfacial diffusion abruptly proceeded resulting in the high interface roughness and the deterioration of the magnetic properties. In order to control the interfacial diffusion at the high temperature, we introduced ${\alpha}-Al_2O_3$ buffer layer ($110-{\AA}-thick$) in the interface of $Ba-ferrite/SiO_2$ thin film. During the annealing of $Ba-ferrite/{\alpha}-Al_2O_3/SiO_2$ thin film even at ${\sim}800^{\circ}C$, the interface was very smooth. The smooth interface of the film was also clearly shown by the cross-sectional FESEM. The magnetic properties, such as saturation magnetization 3nd intrinsic coercivity, were also enhanced, due to the inhibition of interfacial diffusion by the ${\alpha}-Al_2O_3$ buffer layer. Our study suggests that the ${\alpha}-Al_2O_3$ buffer layer act as a useful interfacial diffusion barrier in the $Ba-ferrite/SiO_2$ thin films.

• Journal of Magnetics
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• 제9권4호
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• pp.109-112
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• 2004

The HDDR (Hydrogenation-Disproportionation-Desorption-Recombination) process is a special method to produce anisotropic NdFeB powders for bonded magnet. The effect of the modified HDDR process on magnetic properties of $Nd_2Fe_{14}B$-based magnet with several composition $Nd_{11.2}Fe_{66.5-x}Co_{15.4}B_{6,8}Zr{0.1}Ga_x(x=0{\sim}1.0)$ and that of microelement Ga, disproportional temperature and annealing temperature on $_jH_c$, grain size were investigated in order to produce anisotropic powder with high magnetic properties. It was found that modified HDDR process is very effective to enhance magnetic properties and to fine grain size. The addition of Ga could change disproportionation character remarkably of the alloy and could improve magnetic properties of magnet powder. Increasing annealing temperature induces significant grain growth. And grain size produced by modified HDDR process is significantly smaller than those produced by conventional HDDR process.

• 한국자기학회지
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• 제21권3호
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• pp.93-98
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• 2011

Laser Molecular-Beam Epitaxy 방법을 사용하여 $La_{0.35}Pr_{0.35}Ca_{0.3}MnO_3$(LPCMO)/$LaAlO_3$(LAO) 초격자를 성공적으로 증착하였으며 이의 열처리 전후 결정학적, 자기적 특성을 LPCMO 단층박막, 그리고 LPCMO/$SrTiO_3$(STO) 초격자와 비교 분석하였다. LPCMO 단층박막, 그리고 LPCMO/STO 초격자 단층박막의 경우, 표면이 열처리 전후 모두 거친 양상을 보인 것과는 달리 LPCMO/LAO 초격자 박막은 열처리 전후 모두 상대적으로 매우 매끈하였다. 열처리 후 단층박막, 초격자 박막 시료 모두 강자성 특성이 향상되었으며 특히 초격자의 경우에는 이러한 현상이 두드러졌다. 열처리 후에 보자력과 포화자기장이 감소하는 LPCMO 단층박막과는 달리 LPCMO/LAO 초격자의 경우, 열처리 후에도 보자력은 열처리 전과 같은 값을 보였으며 단층박막과는 반대로 포화자기장은 오히려 증가하였다. 이러한 자기적 특성은 절연체 사이에 강자성체가 끼여 있는 초격자라는 결정구조에서 기인하는 것으로 이해된다.

• 한국정밀공학회지
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• 제6권4호
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• pp.103-107
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• 1989

The effects of annealing temperature on the magnetic properties (maximum permeability, coercive force and remanence) and mechanical properties (hardness, tensile strength and elongation at rupture) were analyzed using the nondestructive impulsive magnetic analyzer in a medium carbon cold rolled steel sheet. This nondestructive method was very useful for the analysis of magnetic and mechanical properties of materials. As it was known in the literature, the three distinct processes that indicate the recovery, recrystallization, and grain growth of a metal were measured with the non-destructive analyzer.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2005년도 하계학술연구발표회 논문개요집
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• pp.148-149
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• 2005

• 한국재료학회지
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• 제33권10호
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• pp.400-405
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• 2023

Tb³⁺-doped CaNb₂O₆ (CaNb₂O₆:Tb³⁺) thin films were deposited on quartz substrates at a growth temperature of 300 ℃ using radio-frequency magnetron sputtering. The deposited thin films were annealed at several annealing temperatures for 20 min and characterized for their structural, morphological, and luminescent properties. The experimental results showed that the annealing temperature had a significant effect on the properties of the CaNb₂O₆:Tb³⁺ thin films. The crystalline structure of the as-grown CaNb₂O₆:Tb³⁺ thin films transformed from amorphous to crystalline after annealing at temperatures greater than or equal to 700 ℃. The emission spectra of the thin films under excitation at 251 nm exhibited a dominant emission band at 546 nm arising from the ⁵D₄→⁷F₅ magnetic dipole transition of Tb³⁺ and three weak emission bands at 489, 586, and 620 nm, respectively. The intensity of the ⁵D₄→⁷F₅ (546 nm) magnetic dipole transition was greater than that of the ⁵D₄→⁷F₆ (489 nm) electrical dipole transition, indicating that the Tb³⁺ ions in the host crystal were located at sites with inversion symmetry. The average transmittance at wavelengths of 370~1,100 nm decreased from 86.8 % at 700 ℃ to 80.5 % at an annealing temperature of 1,000 ℃, and a red shift was observed in the bandgap energy with increasing annealing temperature. These results suggest that the annealing temperature plays a crucial role in developing green light-emitting CaNb₂O₆:Tb³⁺ thin films for application in electroluminescent displays.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.230.2-230.2
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• 2015

Nanoparticles of magnesium ferrite are used as a heterogeneous catalyst, humidity sensor, oxygen sensor and cure of local hyperthermia. These applications usually utilize the magnetic behavior of these nanoparticles. Moreover, magnetic properties of nanoferrites exhibit rather complex behavior compared to bulk ferrite. The magnetic properties of ferrites are complicated by spins at vortices, surface spins. Reports till date indicate strong dependency on the structural parameters, oxidation state of metal ions and their presence in octahedral and tetrahedral environment. Thus we have carried out investigation on magnesium ferrite nanoparticles in order to study coordination, oxidation state and structural distortion. For present work, magnesium ferrite nanoparticles were synthesized using nitrates of metal ions and citric acid. Fe L-edge spectra measured for these nanoparticles shows attributes of $Fe^{3+}$ in high spin state. Moreover O K-edge spectra for these nanoparticles exhibit spectral features that arises due to unoccupied states of O 2p character hybridized with metal ions. Mg K-edge spectra shows spectral features at 1304, 1307, 1311 and 1324 eV for nanoparticles obtained after annealing at 400, 500, 600, 800, 1000, and $1200^{\circ}C$. Apart from this, spectra for precursor and nanoparticles obtained at $300^{\circ}C$ exhibit a broad peak centered around 1305 eV. A shoulde rlike structure is present at 1301 eV in spectra for precursor. This feature does not appear after annealing. After annealing a small kink appear at ~1297 eV in Mg K-edge spectra for all nanoparticles. This indicates changes in local electronic structure during annealing of precursor. Observed behavior of change in local electronic structure will be discussed on the basis of existing theories.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.313-313
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• 2013

For high-performance TFT (Thin film transistor), poly-crystalline semiconductor thin film with low resistivity and high hall carrier mobility is necessary. But, conventional SPC (Solid phase crystallization) process has disadvantages in fabrication such as long annealing time in high temperature or using very expensive Excimer laser. On the contrary, MIC (Metal-induced crystallization) process enables semiconductor thin film crystallization at lower temperature in short annealing time. But, it has been known that the poly-crystalline semiconductor thin film fabricated by MIC methods, has low hall mobility due to the residual metals after crystallization process. In this study, Ni metal was shallow implanted using PIII&D (Plasma Immersion Ion Implantation & Deposition) technique instead of depositing Ni layer to reduce the Ni contamination after annealing. In addition, the effect of external magnetic field during annealing was studied to enhance the amorphous silicon thin film crystallization process. Various thin film analytical techniques such as XRD (X-Ray Diffraction), Raman spectroscopy, and XPS (X-ray Photoelectron Spectroscopy), Hall mobility measurement system were used to investigate the structure and composition of silicon thin film samples.

• 한국자기학회지
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• 제10권2호
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• pp.54-61
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• 2000

마그네트론 스퍼터를 사용하여 증착한 CoNbZr 합금박막의 제조 조건 및 열처리에 따르는 구조 및 자기적 성질의 변화를 연구하였다. Ar분압 2mTorr, RF 인가전력 130 W에서 증착되어진 $Co_{87.0}$N $b_{8.5}$Z $r_{4.5}$막은 최대 비저항 3000 $\mu$Ω.cm을 나타냄으로써 가장 안정한 비정질상을 형성하였으며 100 MHz에서 1095의 최대투자율, 1.75 Oe의 최소 보자력을 나타내었다. Ar 분압이 2 mTorr 이상으로 증가할 경우 그리고 RF 인가전력이 130 W 이상으로 증가할 경우 주상정 구조의 발달과 불안정한 비정질상의 형성으로 투자율은 감소하고 보자력은 증가하는 것을 확인하였다 1 mTorr에서 증착되어진 막과 190 W에서 증착되어진 막은 결정질 상을 형성하여 100 이하의 낮은 투자율과 60 Oe의 높은 보자력을 나타내었다. 회전자장중 열처리에 의해 이방성을 제어할 수 있음을 확인하였으며, 증착상태에서 보였던 1095의 투자율은 1345로 증가하였다.증가하였다.