RF-스퍼터링법을 이용하여 Ni-W 금속기판에 연속공정으로 증착된 $Y_2O_3$ 완충층 특성 연구

Chung, K.C.,Jeong, T.J.,Choi, G.C.,Kim, Y.K.,Wang, X.L.,Dou, S.X. 한국초전도학회 2010 Progress in superconductivity Vol.11 No.2

Reel-to-reel deposition of $Y_2O_3$ has been performed on Ni-5%W metal substrates using the RF-sputtering method. The epitaxial orientation of $Y_2O_3$ buffer layers to the base bi-axially textured substrate was well identified using ${\theta}-2{\theta}$, out-of-plane ($\omega$), and in-plane ($\phi$) scans in X-ray diffraction analysis. The optimization of $Y_2O_3$ seed layers in reel-to-reel fashion were investigated varying the deposition temperature, sputtering power, and pressure for its significant roles for the following buffer stacks and superconducting layers. $Y_2O_3$ were all grown epitaxially on bi-axially textured metal substrates at 380 watts and 5 mTorr in the temperature range of $600-740^{\circ}C$ with higher $Y_2O_3$ (400) intensities at ${\sim}710^{\circ}C$. It was found that the $\Delta\omega$ values were $1-2^{\circ}$ lower but the $\Delta\phi$ values were above $1^{\circ}$ higher than that of Ni-W substrates. As the sputtering power increased from 340 to 380 watts, $\Delta\omega$ and $\Delta\phi$ values showed decreased tendency. Even in the small window of deposition pressure of 3-7 mTorr, the $Y_2O_3$ (400) intensities increased and $\Delta\omega$ and $\Delta\phi$ values were reduced as sputtering pressure increased.

Observation of <tex> $ B^{+}\rightarrow p\overline{p}\pi ^{+}$</tex> , <tex> $ B^{0}\rightarrow p\overline{p}K^{0}$</tex> , and <tex> $ B^{+}\rightarrow p\overline{p}K^{*+}$</tex>

Wang, M.-Z.,Abe, K.,Abe, K.,Abe, T.,Adachi, I.,Aihara, H.,Asano, Y.,Aso, T.,Aulchenko, V.,Aushev, T.,Bakich, A. M.,Bay, A.,Bizjak, I.,Bondar, A.,Bozek, A.,Bra&#x10d,ko, M.,Browder, T. E.,Chang, M.-C. American Physical Society 2004 Physical Review Letters Vol.92 No.13

<P>We report the first observation of a b-->u type charmless baryonic B decay, B+-->pppi(+), as well as b-->s type B0-->ppK0 and B+-->ppK(*+) decays. The analysis is based on a 78 fb(-1) data sample recorded on the Upsilon(4S) resonance with the Belle detector at KEKB. We find B(B+-->pppi(+))=(3.06(+0.73)(-0.62)+/-0.37)x10(-6), B(B0-->ppK0)=(1.88(+0.77)(-0.60)+/-0.23)x10(-6), and B(B+-->ppK(*+))=(10.3(+3.6+1.3)(-2.8-1.7))x10(-6). We also update B(B+-->ppK+)=(5.66(+0.67)(-0.57)+/-0.62)x10(-6) and present an upper limit on B(B0-->ppK(*0)) at the 90% confidence level. A common feature of the observed decay modes is threshold peaking in baryon pair invariant mass.</P>

Fabrications and dielectric performances of novel composites: Calcium copper titanate / Polyvinylidene fluoride

Wang J.J.,Deng Q.J.,He Y.Y.,Feng Y.N.,Kang M.P.,Duan X.L.,Yang Y.L. 한국물리학회 2022 Current Applied Physics Vol.39 No.-

CCTO (Calcium copper titanate) powder as inorganic filler was synthesized by the Sol-gel method firstly. CCTO/ PVDF (Polyvinylidene fluoride) composite was fabricated by solution mixing based on high temperature resistance of PVDF and insulated property of CCTO. The composite of CCTO/PVDF were characterized by X-ray diffraction, Fourier Transform infrared spectroscopy, Scanning Electron Microscope and impedance analysis. The results showed that the addition of CCTO and increasing in its content did not affect the phase- and microstructure of the composites,but the increase of CCTO content can induce the generation of C–F new bonds. PVDF/CCTO composites were enhanced in performance of thermal and frequency-depended stability with increasing in the fraction of CCTO. The dielectric constant of CCTO/PVDF composite materials with 50% CCTO achieved to a maximum value of 50 almost, which is 5 times higher the pure PVDF. The conductivity felled into 10-8 to 10-1 S m-1 during the frequency of 102–108 Hz. The composite material would be expected to be applied in the field of integrated circuit.

Effect of surface modification layer thickness on the gas sensitivity of SnO2 films

Y.H. Xiong,L. Wang,X.Y. Wei,G.R. Qin,C.H. Mao,J. Du 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

Nickel was used as a surface modification material to enhance the gas-sensing properties of SnO2 films. The thickness of the Ni modification layer was controlled by the sputtering time. The surface morphology and surface chemical composition of the surface modification layers of different thicknesses were analyzed by Field Emission Scanning Electron Microscopy (FESEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The gas sensitivity to clean air with a low hydrogen concentration of 1000 ppm of the modified tin dioxide thin films was investigated at temperatures from 20oC to 100oC. The results show that the thickness of the modification layer plays an important role in the enhancement of the gas-sensing properties and surface electric properties of SnO2 films. A Ni modification layer with a thickness of 50 nm on the surface of a SnO2 film can improve the hydrogen gas sensitivity of a SnO2 film up to 112%, and reduce the response time to 80s. Nickel was used as a surface modification material to enhance the gas-sensing properties of SnO2 films. The thickness of the Ni modification layer was controlled by the sputtering time. The surface morphology and surface chemical composition of the surface modification layers of different thicknesses were analyzed by Field Emission Scanning Electron Microscopy (FESEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The gas sensitivity to clean air with a low hydrogen concentration of 1000 ppm of the modified tin dioxide thin films was investigated at temperatures from 20oC to 100oC. The results show that the thickness of the modification layer plays an important role in the enhancement of the gas-sensing properties and surface electric properties of SnO2 films. A Ni modification layer with a thickness of 50 nm on the surface of a SnO2 film can improve the hydrogen gas sensitivity of a SnO2 film up to 112%, and reduce the response time to 80s.

Stimulated Release of Size‐Selected Cargos in Succession from Mesoporous Silica Nanoparticles

Wang, Cheng,Li, Zongxi,Cao, Dennis,Zhao, Yan&#x2010,Li,Gaines, Justin W.,Bozdemir, O. Altan,Ambrogio, Michael W.,Frasconi, Marco,Botros, Youssry Y.,Zink, Jeffrey I.,Stoddart, J. Fraser WILEY‐VCH Verlag 2012 Angewandte Chemie Vol.124 No.22

<P><B>Zwei Fliegen mit einer Klappe</B>: Die kovalente Bindung von β‐Cyclodextrin (gelb; siehe Bild) an mesoporöse Siliciumdioxid‐Nanopartikel (MSNs) ergibt ein duales Freisetzungssystem, das mit unterschiedlich großen Wirkstoffen (blaue und rote Kugeln) beladen werden kann, die sich auf verschiedene Stimuli hin nacheinander freisetzen lassen. Die kleineren Moleküle werden durch Absenken des pH‐Wertes freigesetzt, die größeren nach Abspaltung der Cyclodextrine von der MSN‐Oberfläche.</P>

MHD Instability Fluctuation Measurement on the HL-2A Tokamak by Using the HCN Laser Interferometer

Y. G. Li,Y. Zhou,Z. C. Deng,J. Yi,Y. Li,H. X. Wang,X. Q. Ji,W. Deng 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.8

The multichannel HCN laser interferometer has been routinely used to measure the electron density(ne) on the HL-2A tokamak for several years. In order to explore its capability for qualitativelyevaluating the Magnetohydrodynamic (MHD) fluctuation in plasmas from the probing signal, weimplemented two important modifications on the hardware of channel #3 (r = −10.5 cm): (1) applicationof the high-response Schottky diode waveguide detector, and (2) utilization of a preamplifierwith a broad pass-band of up to 500 kHz so as not to filter the fluctuation component mixed withthe intermediate frequency (IF). Many MHD fluctuation phenomena, such as tearing modes (TMs),fishbones, long lived modes (LLMs), have been successfully detected by using the modified channel#3 in the HL-2A experimental campaign, and the results were quite coincident with those derivedfrom the magnetic probe and the soft X-ray systems. We propose to apply this novel approach tomore channels of the HCN laser interferometer.

Microstructure and Mechanical Properties of CoCrFeMnNiSnx High‑Entropy Alloys

X. Y. Gu,Y. N. Dong,Y. X. Zhuang,J. Wang 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.3

The objective of this study is to investigate the effect of Sn content on the microstructure and mechanical properties of theCoCrFeMnNiSnxhigh entropy alloys. The microstructure and mechanical properties of the alloys have been studied by X-raydiffraction, scanning electron microscopy, room-temperature compressive tests and Vickers hardness tests. It has been foundthat Sn has a great effect on the microstructure and mechanical properties of the alloys. The CoCrFeMnNi alloy has a simpleFCC phase structure, while a few white precipitations (MnNi2Sn-like) are observed in the Sn0.03and Sn0.07alloys. With furtheradditions of Sn, the microstructure of Sn0.1,Sn0.3and Sn0.5changes to a typical dendrite structure, the dominated dendriteregion has a lattice of FCC structure which is enriched with Cr, Co and Fe, and the interdendritic region is enriched withMn, Ni and Sn. The volume of the MnNi2Sn-like phase increases with Sn content increasing. The addition of Sn enhancesthe formation of the MnNi2Sn-like phase in the CoCrFeMnNiSnxalloys, and improves the hardness and strength of as-castalloys, but reduces the ductility of the alloys. The strengthening mechanism of alloys was solid solution strengthening andformation of the MnNi2Sn-like phase. In the CoCrFeMnNiSn0.03and CoCrFeMnNiSn0.07alloys, the solid solution is thedominant mechanism. With the Sn content increasing, the second phase strengthening is the dominant mechanism.

Influences of the Irradiation of Intense Pulsed Ion Beam (IPIB) on the Surface of Ni₃Al Base Alloy IC6

X. Y. Le,S. Yan,W. J. Zhao,B. H. Han,Y. G. Wang,J. M. Xue,H. T. Zhang 한국진공학회(ASCT) 2002 Journal of Korean Vacuum Science & Technology Vol.6 No.2

In this paper, we treated the Ni₃Al based alloy samples with intense pulsed ion beams (IPIB) at the beam parameters of 250KV acceleration voltage, 100 - 200 A/㎤ current density and 60 ㎱ pulse duration. We simulated the thermal-mechanical process near the surface of Ni₃Al based alloy with our STEIPIB codes. The surface morphology and the cross-section microstructures of samples were observed with SEM, the composition of the sample surface layer was determined by X-ray Energy Dispersive Spectrometry (XEDS) and the microstructure on the surface was observed by Transmission Electron Microscope (TEM). The results show that heating rate increases with the current density of IPIB and cooling rate reached highest value less than 150 A/㎤. The irradiation of IPIB induced the segregation of Mo and adequate beam parameter can improve anti-oxidation property of IC6 alloy. Some craters come from extraneous debris and liquid droplets, and some maybe due to the melting of the intersection region of interphase. Increasing the pulse number enlarges average size of craters and decreases number density of craters.

Microstructure and Properties of the Cr–Si–N Coatings Deposited by Combining High-Power Impulse Magnetron Sputtering (HiPIMS) and Pulsed DC Magnetron Sputtering

Wang, T. G.,Dong, Y.,Gebrekidan, B. A.,Liu, Y. M.,Fan, Q. X.,Kim, K. H. Springer Science + Business Media 2017 Acta metallurgica sinica Vol.30 No.7

<P>The Cr-Si-N coatings were prepared by combining system of high-power impulse magnetron sputtering and pulsed DC magnetron sputtering. The Si content in the coating was adjusted by changing the sputtering power of the Si target. By virtue of electron-probe microanalysis, X-ray diffraction analysis and scanning electron microscopy, the influence of the Si content on the coating composition, phase constituents, deposition rate, surface morphology and microstructure was investigated systematically. In addition, the change rules of micro-hardness, internal stress, adhesion, friction coefficient and wear rate with increasing Si content were also obtained. In this work, the precipitation of silicon in the coating was found. With increasing Si content, the coating microstructure gradually evolved from continuous columnar to discontinuous columnar and quasi-equiaxed crystals; accordingly, the coating inner stress first declined sharply and then kept almost constant. Both the coating hardness and the friction coefficient have the same change tendency with the increase of the Si content, namely increasing at first and then decreasing. The Cr-Si-N coating presented the highest hardness and average friction coefficient for an Si content of about 9.7 at.%, but the wear resistance decreased slightly due to the high brittleness. The above phenomenon was attributed to a microstructural evolution of the Cr-Si-N coatings induced by the silicon addition.</P>

Thermoelectric properties of Gd, Y co-doped Ca3Co4O9+δ

H.Q. Liu,X.B. Zhao,T.J. Zhu,Y. Song,F.P. Wang 한국물리학회 2009 Current Applied Physics Vol.9 No.3

The Ca3-x-yGdxYyCo4O9+δ precursor powders were synthesized by the polyacrylamide gel method. The powders were sintered by the spark plasma sintering (SPS). The DTA analysis showed that the synthesis temperature of Ca3Co4O9+δ was about 933 K, which is lower than that of the conventional citric acid method. The resistivities, the Seebeck coefficients and the thermal conductivities of the samples were measured from room temperature to 973 K. The Seebeck coefficients and the resistivities of the doped samples were remarkably enhanced due to the decrease of the carrier concentration, whereas the thermal conductivities of them were decreased due to the impurity scattering effect. The maximal ZT value of 0.26 was obtained at 973 K for Ca2.7 Gd0.15 Y0.15Co4O9+δ. The Ca3-x-yGdxYyCo4O9+δ precursor powders were synthesized by the polyacrylamide gel method. The powders were sintered by the spark plasma sintering (SPS). The DTA analysis showed that the synthesis temperature of Ca3Co4O9+δ was about 933 K, which is lower than that of the conventional citric acid method. The resistivities, the Seebeck coefficients and the thermal conductivities of the samples were measured from room temperature to 973 K. The Seebeck coefficients and the resistivities of the doped samples were remarkably enhanced due to the decrease of the carrier concentration, whereas the thermal conductivities of them were decreased due to the impurity scattering effect. The maximal ZT value of 0.26 was obtained at 973 K for Ca2.7 Gd0.15 Y0.15Co4O9+δ.