• 환경위생공학
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• 제18권3호통권49호
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• pp.35-42
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• 2003

The electric resistance and constant current were investigated on the nickel-thallium-phosphorus alloy deposits by electroless-plating. The Ni-Tl-P alloy deposits were achieved with a bath using sodium hypophosphit as the reducing agent and sodium citrate as the comlexing agent. The basic plating solution is composed of 0.1M NiSO$_4$, 0.005${\sim}$0.0IM Tl$_2$S0$_4$, 0.1${\sim}$O.2M sodium hypophosphite and 0.02${\sim}$O.IM sodium citrate and the plating condition were pH 5${\sim}$6, temperrature 80$_4$90${\circ}$C. The results obtained are summarized as follows: 1) The crystal structure of deposit was amorphous structure as deposited state, became microcrystallized centering on Ni(111) plane by heat treatment at 200${\circ}$C, and grew as polycrystalline Ni, Ni$_3$P, Ni$_5$p$_2$,Tl, etc. by heat treatment higher than 350${\circ}$C. The grain size of plated deposits was grown up to 28.3~42.0nm by heat treatment for 1hour at 500${\circ}$C. 2) The electrical resistivity showed a comparatively high value of 192.5$_4$208.3 ${\mu}$${\Omega}$Cm and its thermal stability was great with resistivity value less than 0.22% in the thermal surroundings of 200${\circ}$C. 3) Ni-Tl-P alloy deposit showed such good constant current-making-effect in the variation of electric voltage, heat treatment temperature, and the composition of the deposit that it can be put to practical use as the matter of constant current device.

• 한국전기전자재료학회논문지
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• 제27권11호
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• pp.760-765
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• 2014

MgZnO has attracted a lot of attention for flexible device. In the flexible substrate, the crystal structure of the thin films as well as the surface morphology is not good. Therefore, in this study, we studied on the effects of the oxygen pressure on the structure and crystallinity of $Mg_{0.3}Zn_{0.7}O$ thin films deposited on PES substrate by using pulsed laser deposition. We used X-ray diffraction and atomic force microscopy in order to observe the structural characteristics of $Mg_{0.3}Zn_{0.7}O$ thin films. The crystallinity of $Mg_{0.3}Zn_{0.7}O$ thin films with increasing temperature was improved, Grain size and RMS of the films were increased. UV-visible spectrophotometer was used to get the band gap energy and transmittance. $Mg_{0.3}Zn_{0.7}O$ thin films showed high transmittance over 90% in the visible region. As increased working pressure from 30 mTorr to 200 mTorr, the bandgap energy of $Mg_{0.3}Zn_{0.7}O$ thin film were decreased from 3.59 eV to 3.50 eV.

• 한국재료학회지
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• 제20권9호
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• pp.494-499
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• 2010

Tin oxide thin films were prepared on borosilicate glass by rf reactive sputtering at different deposition powers, process pressures and substrate temperatures. The ratio of oxygen/argon gas flow was fixed as 10 sccm / 60 sccm in this study. The structural, electrical and optical properties were examined by the design of experiment to evaluate the optimized processing conditions. The Taguchi method was used in this study. The films were characterized by X-ray diffraction, UV-Vis spectrometer, Hall effect measurements and atomic force microscope. Tin oxide thin films exhibited three types of crystal structures, namely, amorphous, SnO and $SnO_2$. In the case of amorphous thin films the optical band gap was widely spread from 2.30 to 3.36 eV and showed n-type conductivity. While the SnO thin films had an optical band gap of 2.24-2.49 eV and revealed p-type conductivity, the $SnO_2$ thin films showed an optical band gap of 3.33-3.63 eV and n-type conductivity. Among the three process parameters, the plasma power had the most impact on changing the structural, electrical and optical properties of the tin oxide thin films. It was also found that the grain size of the tin oxide thin films was dependent on the substrate temperature. However, the substrate temperature has very little effect on electrical and optical properties.

• 한국광물학회지
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• 제30권3호
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• pp.127-136
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• 2017

자외선 차단기능과 제균 기능을 갖는 합성 $TiO_2$-복합체에 대해 압력의 영향을 체크하기 위해 고압실험을 시행하였다. 복합체 분말시료는 아나타제와 루틸 및 염화은으로 구성되어 있으며, 입자크기는 34 nm 정도로 결정되었다. 아나타제와 루틸 모두 약 14~16 GPa 구간에서 $ZrO_2$ (배델레이트)-형태의 결정구조로 상변이하며, 본 실험의 최고압력인 22.7 GPa까지 상변이는 계속된다. 압력을 모두 제거하여 상압 상태가 되면, 루틸은 ${\alpha}-PbO_2$ 구조로 상변이하며 아나타제는 고압의 $ZrO_2$-결정구조가 유지되는 것으로 판단된다. 염화은의 회절피크는 낮은 압력에서 사라지는 것이 관찰되었다.

• 한국세라믹학회지
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• 제53권2호
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• pp.145-149
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• 2016

$(Bi_{1/2}Na_{1/2})_{0.94}Ba_{0.06}(Ti_{1-x}Nb_x)O_3$ (BNBTxNb) ceramics were investigated in terms of the crystal structure as well as the ferroelectric, dielectric, and piezoelectric properties. While little change was observed in the microstructure except for a slight decrease in the average grain size, a significant change was noticed in the temperature dependence of dielectric and piezoelectric properties. It was shown that the property changes are closely related to the downward shift in the position of the ferroelectric-to-relaxor transition temperature with increasing amount of Nb doping. A special emphasis is put on the fact that Nb doping is so effective at decreasing the ferroelectric-to-relaxor transition temperature that even at no more than 2 at.% Nb addition, the transition temperature was already brought down slightly below room temperature, resulting in the birth of a large strain at 0.46 %, equivalent to $S_{max}/E_{max}=767pm/V$.

• 한국전기전자재료학회논문지
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• 제25권9호
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• pp.717-722
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• 2012

In this work, we study on the effects of the oxygen pressure on the structural and crystalline of MgZnO thin films. MgZnO thin films were deposited on p-Si (111) substrates by using pulsed laser deposition. The X-ray diffraction analysis and energy-dispersive X-ray results revealed that as the oxygen pressure increased and Mg content in the MgZnO films decreased. Also Crystal structure was changed from cubic rock salt to hexagonal wurtzite. Alpha step and atomic force microscopy results showed that the thickness of the films are about 100 nm, and it has been found that the MgZnO (002) preferred orientation were deposited with increasing the oxygen pressure. Therefore, the effect of the preferred orientation, the crystallization grew in the form of the columnar; Grain size and RMS of the films were increased with increasing oxygen pressure.

• 한국수소및신에너지학회논문집
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• 제28권3호
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• pp.238-245
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• 2017

Mg-Ni nanoparticles were synthesized by a physical vapor condensation method (DC arc-discharge) in a mixture of argon and hydrogen atmosphere, using compressed mixture of micro powders as the raw materials. The crystal phases, morphology, and microstructures of nanoparticles were analyzed by means of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). It was found that the intermetallic compounds of $Mg_2Ni$ and $Mg_2Ni$ formed with existence of phases of Mg, Ni, and MgO in Mg-Ni nanoparticles. After one cycle of hydrogen absorption/desorption process (activation treatment), Mg-Ni nanoparticles exhibited excellent hydrogen absorption properties. $Mg_2Ni$ phase became the main phase by aphase transformation during the hydrogen treatments. The phenomenon of refinement of grain size in the nanoparticle was also observed after the hydrogen absorption/desorption processes, which was attributed to the effect of volume expansion/shrinkage and subsequent break of nanoparticles. Maximum hydrogen absorption contents are 1.75, 2.21 and 2.77 wt.% at 523, 573 and 623 K, respectively.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.37-40
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• 2016

We have investigated the addition effect of NiO magnetic nanoparticles on crystal structure, microstructure as well as superconducting properties of $MgB_2$. NiO-added $MgB_2$ samples were prepared by the solid-state reaction method. The superconducting transition temperature ($T_c$) of 37.91 K was obtained for pure $MgB_2$, and $T_c$ was found to decrease systematically on increasing the addition level of NiO. X-ray diffraction (XRD) analysis revealed that no substitution of Ni for Mg in the lattice of $MgB_2$ was occurred. The microstructural analysis shows that the pure $MgB_2$ sample consists of plate shape $MgB_2$ grains, and the grains get refined to smaller size with the addition of NiO nanoparticles. At 5 K, high values of critical current density ($J_c$) were obtained for small amount NiO-added $MgB_2$ samples as compared to pure sample. The enhancement in $J_c$ could be attributed to the refinement of $MgB_2$ grains which leads to high density of grain boundaries in NiO-added $MgB_2$ samples.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1418-1420
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• 1996

In this paper, structural properties of CdTe thin films and photovoltaic properties of thin film CdS/CdTe solar ceIl prepared by thermal vacuum evaporation were studied. Structural variation with $CdCl_2/heat$ treatment are assessed using x-ray diffraction and scanning electron microscopy. The crystal structure of CdTe films was zincblend type with preferential orientation of the (111) plane parallel to the substrate. The $CdCl_2$ treatment appears to increase the grain size of polycrystalline CdTe thin film. It was found that CdS/CdTe solar cell characteristics were improved by the heat treatment with $CdCl_2$. The conversion efficiency, however, decreased when heat treatment temperature was too high.

• 한국표면공학회지
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• 제51권2호
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• pp.116-125
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• 2018

Aluminum-doped zinc oxide (AZO) is a commonly used material for the front contact layer of chalcopyrite $CuInGaSe_2$ (CIGS) based thin film solar cells since it satisfies the requisite optical and electrical properties with low cost and abundant elemental availability. Low-resistivity and high-transmission front contacts have been developed for high-performance CIGS solar cells, and nearly meet the required performance. However, the durability of the cell especially for the corrosion resistance of AZO films has not been studied intensively. In this work, AZO films were prepared on Corning glass 7059 substrates by radio frequency magnetron sputtering depending on the hydrogen content. The electrical and optical properties and electrochemical corrosion resistance of the AZO films were evaluated as a function of the hydrogen content. With increasing hydrogen content to 6 wt%, the crystallinity, crystal size, and surface roughness of the films increased, and the resistivity decreased with increased carrier concentration, Hall mobility, oxygen vacancies, and $Zn(OH)_2$ binding on the AZO surface. At a hydrogen content of 6 wt%, the corrosion resistance was also relatively high with less columnar morphology, shallow pore channels, and lower grain boundary angles.