• Korean Journal of Materials Research
• /
• v.6 no.8
• /
• pp.796-800
• /
• 1996

질소가스 분위기 중에서 Cu30V70 및 Fe30Cr70 혼합분말을 기계적 합금화 (MA)처리한 결과, 두 합금계에서 비정질화가 관찰되었다. 결정질에서 비정질상으로의 구조변화 과정을 Xtjs 회절 및 중성자 회절법에 의해 관찰되었다. 결정질에서 비정질상으로의 구조변화 과정을 X선 회절 및 중성자 회절법에 의해 관찰하였다. 그 결과, 이 합금계에서의 비정질화는 각 결정구조에서 전형적으로 존재하는 8면체 unit가 선택적으로 붕괴되어 4면체 unit로 변화되어 가는 과정임을 알 수 있었다. 또한, 중성자회절 결과로부터 질소원자는 금속원자로 이루어진 4면체의 중심에 위치하고 있음을 알 수 있었다.

• Korean Journal of Crystallography
• /
• v.13 no.3_4
• /
• pp.152-157
• /
• 2002

The molecular and crystal structure of Tricyclazole, C/sub9/H/sub7/N₃S, has been determined by single crystal x-ray diffraction study. Crystallographic data for title compound: Pca2₁, a=14.889(1) Å, b=7.444(1) Å, c=15.189(2) Å, V=1683.3(3) ų, Z= 8. The molecular structure model was solved by direct methods and refined by full-matrix least-squares. The final reliable factor, R, is 0.047 for 1533 independent reflections (F/sub o//sup 2/)). The asymmetry unit contains two molecules which are in plate conformation, parallel to each other and related by a pseudo four-fold screw on the b-direction.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.22 no.1
• /
• pp.51-56
• /
• 2012

In the present study, we investigated the effect of mechanical alloying (MA) on the formation of amorphous VCo system through solid state reaction during ball milling. Two types of powder samples, ${\sigma}$-VCo intermetallic compound and $V_{50}Co_{50}$ powder mixture, were applied as a starting materials. With increasing milling time, a structural characteristics into the amorphous state is distinctly observed from the structural factor and radial distribution by X-ray diffraction. Amorphization has been observed in all two types of samples after the milling for 120 hrs. DSC spectrum of $V_{50}Co_{50}$ powder sample milled for 60 hrs indicates a sharp exothermic peak from the crystallization at $600^{\circ}C$. The structure factor, S(Q) and radial distribution function, RDF(r), observed by X-ray diffraction gradually change into a structure characteristic of an amorphous state with increasing MA time.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.10 no.3
• /
• pp.264-270
• /
• 2000

Quantitative analysis of iron ore sinter consisting of hematite, magnetite, calcium ferrite and slag was investigated by X-ray internal standard method. After selecting NaF and $SiO_2$as internal standard materials, the calibration curves were determined and were applied to quantitative analysis of the internal standard method. Calcium ferrite was identified as a solid solution of CaO.$2Fe_2$$O_3$with 7 wt% and 3 wt% solubility of $AI_2$$O_3$and $SiO_2$, respectively. The maximum deviation of quantitative analysis of synthetic iron ore was about $\pm$5 wt%. The contents of each mineral calculated in industrial sinter were 27~40 wt% of hematite, 20~30 wt% of magnetite, 22~33 wt% of calcium ferrite and 10~20 wt% of slag.

• Proceedings of the KAIS Fall Conference
• /
• 2001.05a
• /
• pp.220-223
• /
• 2001

Pb가 10% 과잉되고 Zr : Ti = 52 : 48 조성을 갖는 PZT sol이 Pt(3500Å)/Ti(400Å)/SiO₂(3000Å)Si(525㎛)기판 위에 스핀 코팅법으로 반복 코팅된 후, 450℃에서 10분, 650℃에서 2분간 반복 열처리되었다. 이와 같이 다양한 두께로 적층된 박막은 각 시편에 대해 최종적으로 650℃ 30분 동안 어닐링 처리되었다. 제조된 PZT 박막의 두께는 4100Å에서 1.75㎛사이의 4종이었다. 이어서 스퍼터링법으로 Pt전극이 PZT 막 위에 증착되었다. 제조된 PZT 박막의 결정 구조 조사를 위해 XRD, 그리고 미세 구조 및 전기적 특성을 알아보기 위해 FESEM과 P-E 이력 곡선이 각각 관찰되었다. 4100Å에서 1.75㎛까지 두께 증가에 따른 장비상의 포화 이력 한계로 잔류 분극(Pr)값이 25μC/㎠에서 다소 감소되었다. 측정된 X선 회절 결과에서 최초 4회 코팅시 perovskite 결정 구조로 성장한 결정립은 (111)배향이 우세하었으나, 두께가 증가됨에 따라 (111)/(110)값이 감소되었으며, 이를 통해 두께 증가에 따른 (111)배향성이 다소 감소됨을 알 수 있었다. 이상의 결과로부터 제조된 PZT 박막은 큰 힘과 높은 내전압 특성을 갖는 마이크로 압전 액츄에이터에 적용될 수 있을 것으로 생각되었다.

• Electrical & Electronic Materials
• /
• v.7 no.4
• /
• pp.331-340
• /
• 1994

Polysilicon on insulator has been recrystallized by zone melting recrystallization method with graphite strip heaters. Experiments are performed with non-seed SOI structures. When the capping layer thickness of Si$\_$3/N$\_$4//SiO$\_$2/ is 2.0.mu.m, grain boundaries are about 120.mu.m spacing and protrusions reduced. After the seed SOI films are annealed at 1100.deg. C in NH$\_$3/ ambient for 3 hours, the recrystallized silicon surface has convex shape. After ZMR process, the tensile stress is 2.49*10$\^$9/dyn/cm$\^$2/ and 3.74*10$\^$9/dyn/cm$\^$2/ in the seed edge and seed center regions. The phenomenon of convex shape and tensile stress difference are completely eliminated by using the PSG/SiO$\_$2/ capping layer. The characterization of SOI films are showed that the SOI films are improved in wetting properties. N channel SOI MOSFET has been fabricated to investigate the electrical characteristics of the recrystallized SOI films. In the 0.7.mu.m thickness SOI MOSFET, kink effects due to the floating substrate occur and the electron mobility was calculated from the measured g$\_$m/ characteristics, which is about 589cm$\^$2//V.s. The recrystallized SOI films are shown to be a good single crystal silicon.

• Journal of the Korean Magnetics Society
• /
• v.17 no.2
• /
• pp.71-75
• /
• 2007

Ultrasonic irradiation in a solution during the chemical reaction may accelerate the rate of the reaction and the crystallization at low temperature. We have synthesized nanometer sized zinc ferrite particles using chemical co-precipitation technique through a sonochemical method with surfactant such as oleic acid. The thermal behaviour of the zinc ferrite was determined by the thermoanalytical techniques (TGA-DSC). Powder X-ray diffraction measurements show that the samples have the spinel structure. Magnetic properties measurement were performed using a superconducting quantum interference device (SQUID) magnetometer.

• Analytical Science and Technology
• /
• v.11 no.1
• /
• pp.42-46
• /
• 1998

The reaction of $({\eta}^5-C_5Me_5)_2K$ with $BiCl_3$ yielded $({\eta}^5-C_5Me_5)_2BiCl$[I], the first organobismuth compound with ${\pi}$-bonded cyclopentadienyl ring. The compound I which was the violet crystal (yield, 30%) was decomposed to $PCpBiCl_2$. The Structure of $({\eta}^5-C_5Me_5)_2BiCl$ was identified as single crystal by X-ray diffraction method. The eliminated product $C_{20}H_{30}$, triclinic crystal of space group p1(Z=2) which was attached with C-C ${\sigma}$-bond of two cyclopentadienyl was defined by the structural analysis.

• Journal of the Korean Society of Radiology
• /
• v.13 no.4
• /
• pp.645-652
• /
• 2019

Phosphor with phosphorus doped with rare earth ions was investigated by searching Sr and Eu phosphors suitable for substitution of Eu ions with similar ionic radius to polyphosphate host. The $NaSr(PO_3)_3$ phosphor was synthesized by the solid state method and the $NaSr(PO_3)_3:Eu^{2+}$ phosphor was prepared by the carbon thermal reduction method. Both of the phosphors were identified by X - ray diffraction. The excitation and emission spectra of $NaSr(PO_3)_3:Eu^{3+}$ increased fluorescence intensity and intensity quenching with increasing $Eu^{3+}$ concentration. The higher the $Eu^{3+}$ concentration in the emission spectrum, the higher the local symmetry of $Eu^{3+}$ environment. The mechanism of concentration quenching, in which fluorescence decreases due to the energy transfer between $Eu^{2+}$ ions with the closest critical distance between $Eu^{2+}$ ions with increasing $Eu^{2+}$ ion concentration, was confirmed in the emission spectrum of $NaSr(PO_3)_3:Eu^{2+}$ concentration. It is possible to change the fluorescent region through the post-processing of single rare earth ion added phosphors, and it is possible to change the fluorescence by applying the energy transfer and concentration quenching mechanism according to the local symmetry of $Eu^{3+}$ will be used for high phosphor development.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.26.2-26.2
• /
• 2011

최근 주목 받고 있는 산화아연(ZnO)은 레이저 다이오드, 가스 센서, 자외선 센서, 투명전극 등으로 다양하게 사용될 수 있어 연구개발이 폭 넓게 이루어지고 있는 상황이다. 특히, 3.3 eV의 direct bandgap 에너지를 가지고 있는 ZnO은 현재 자외선센서로 많이 적용되고 있는 물질인 GaN계열을 대체할 수 있는 유망한 물질로 주목 받고 있다. 공기중의 산소나 수분의 표면반응에 의한 자외선 측정을 하는 ZnO을 나노선으로 만들게 되면, 표면대비 부피비가 박막에 비해 급격히 증가하기 때문에 민감도가 커지고 반응시간이 짧아지게 된다. 본 연구에서는 자외선센서의 민감도와 반응성을 향상시키기 위해 전기화학적 합성법을 통해 ZnO의 박막과 나노선을 제조하였다. 사진공정을 통해 3 ${\mu}m$의 간격을 가진 금(Au) 전극을 만든 후, 전기화학적 합성법을 통해 아연이온이 포함된 용액에서 정전류를 흘려보내 아연 또는 ZnO을 증착시킬 수 있었다. 첫 번째로 ZnO을 양쪽 Au 전극에서 동시에 증착하여 두 박막이 접합하였고, 두 번째는 100nm의 지름을 가진 Ni 나노선를 전극 양쪽에서 자석을 통해 자기장을 형성해 정렬시키고 ZnO을 Au 전극과 Ni 나노선에 증착한 후, Ni 나노선를 산화시킴으로써, ZnO 나노구조를 형성하였다. 세 번째로는 Au 전극 양쪽에 아연을 전기화학적 합성을 하여 박막으로 증착하고 고온에서 산화과정을 통해 100 nm 이하의 지름을 가진 ZnO 나노선를 형성하였다. 이렇게 만들어진 세가지 구조의 ZnO의 나노구조와 결정성은 주사전자현미경과 X선 회절 분석기를 통해 측정하였으며, 자외선에 대한 민감도와 반응성은 365 nm의 파장을 가진 자외선발생기와 소스미터장치를 통해 측정하였다. 박막에서 100 nm 이하의 지름을 가진 ZnO 나노선로 갈 수록 자외선에 대한 민감도와 반응성이 향상되었다.