• Title/Summary/Keyword: Ni/MgO.

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Dielectric and Piezoelectric Properties of Low Temperature Sintering PMW-PNN-PZT Substituted with CeMnO3 (CeMnO3가 치환된 저온소결 PMW-PNN-PZT 세라믹스의 유전 및 압전 특성)

  • Kim, Yong-Jin;Yoo, Ju-Hyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.3
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    • pp.160-164
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    • 2015
  • In this study, $(1-x)Pb(Mg_{1/2}W_{1/2})_{0.03}(Ni_{1/3}Nb_{2/3})_{0.09}(Zr_{0.5}Ti_{0.5})_{0.88}O_3+xCeMnO_3$ (x= 0~0.02) ceramics were prepared by Columbite precursor method. The phase structure, ferroelectric and piezoelectric properties were systematically investigated. It was found that PMW-PNN-PZT possessed superior electrical properties due to its composition close to the MPB (morphotropic phase boundary). Coercive electric field of 10.05 [kV/cm] and density of 7.88 [$g/cm^3$] were obtained when the substitution amount of $CeMnO_3$ is x=0.02. In contrast, specimens with x=0.01 showed the mechanical quality factor($Q_m$) of 1,091 and the electromechanical coupling factor($k_p$) of 0.613.

A Study on the Steam-Hydrocarbon Reforming Catalysts (탄화수소의 수증기개질 촉매에 관한 연구)

  • Lee Mook Kwon;Tae Soon Kim
    • Journal of the Korean Chemical Society
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    • v.15 no.2
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    • pp.55-63
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    • 1971
  • In this study, several nickel catalysts for the steam-hydrocarbon reforming process were prepared from various nickel salt, magnesium oxide, alumina and kaolinite. The activity and strength of the catalysts were investigated. 1. The proper composition of the calcined catalysts are: NiO (5-15%)-MgO(10-20%)-$Al_2O_3$(10-40%)-Kaolinite(50-80%). 2. The admixed or cosedimented ingredients of the catalysts was pelletized and calcinated at 1000 or $1150^{\circ}C$. Calcination at $1150^{\circ}C$ for an hour was optimum. 3. The water to oil ratio (W/O) for reforming of hexane should be above 7 mole/mole. As the W/O increases, more carbon dioxide and hydrogen, but less carbon monoxide was produced. Also carbon deposition become lessen at higher W/O. 4. Maximum conversion had attained at about $850^{\circ}C$. As the reaction temperature increases, more carbon monoxide and hydrogen, but less carbon dioxide and lower hydrocarbon was produced. 5. The percent conversion at $850^{\circ}C$ was about 80%, using a catalyst which the nickel oxide content are 5%.

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Occurrence and Chemical Composition of Dolomite and Chlorite from Xiquegou Pb-Zn Deposit, China (중국 Xiquegou 연-아연 광상의 돌로마이트와 녹니석 산상과 화학조성)

  • Yoo, Bong Chul
    • Korean Journal of Mineralogy and Petrology
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    • v.35 no.2
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    • pp.125-140
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    • 2022
  • The Xiquegou Pb-Zn deposit is located at the Qingchengzi orefield which is one of the largest Pb-Zn mineralized zone in the northeast of China. The geology of this deposit consists of Archean granulite, Paleoproterozoinc migmatitic granite, Paleo-Mesoproterozoic sodic granite, Paleoproterozoic Liaohe group, Mesozoic diorite and Mesozoic monzoritic granite. The Xiquegou deposit which is a Triassic magma-hydrothermal type deposit occurs as vein ore filled fractures along fault zone in unit 3 (dolomitic marble and schist) of Dashiqiao formation of the Paleoproterozoic Liaohe group. Xiquegou Pb-Zn deposit consists of quartz, apatite, calcite, pyrite, arsenopyrite, pyrrhotite, marcasite, sphalerite, chalcopyrite, stannite, galena, tetrahedrite, electrum, argentite, native silver and pyrargyrite. Wallrock alteration of this deposit contains silicification, pyritization, dolomitization, chloritization and sericitization. Based on mineral petrography and paragenesis, dolomites from this deposit are classified two type (1. dolomite (D0) as wallrock, 2. dolomite (D1) as wallrock alteration in Pb-Zn mineralization quartz vein ore). The structural formulars of dolomites are determined to be Ca1.03-1.01Mg0.95-0.83Fe0.12-0.02Mn0.02-0.00(CO3)2(D0) and Ca1.16-1.00Mg0.79-0.44Fe0.53-0.13Mn0.03-0.00As0.01-0.00(CO3)2(D1), respectively. It means that dolomites from the Xiquegou deposit have higher content of trace elements compared to the theoretical composition of dolomite. The dolomite (D1) from quartz vein ore has higher content of these trace elements (FeO, PbO, Sb2O5 and As2O5) than dolomite (D0) from wallrock. Dolomites correspond to Ferroan dolomite (D0), and ankerite and Ferroan dolomite (D1), respectively. The structural formular of chlorite from quartz vein ore is (Mg1.65-1.08Fe2.94-2.50Mn0.01-0.00Zn0.01-0.00Ni0.01-0.00Cr0.02-0.00V0.01-0.00Hf0.01-0.00Pb0.01-0.00Cu0.01-0.00As0.03-0.00Ca0.02-0.01Al1.68-1.61)5.77-5.73(Si2.84-2.76Al1.24-1.16)4.00O10(OH)8. It indicated that chlorite of quartz vein ore is similar with theoretical chlorite and corresponds to Fe-rich chlorite. Compositional variations in chlorite from quartz vein ore are caused by mainly octahedral Fe2+ <-> Mg2+ (Mn2+) substitution and partly phengitic or Tschermark substitution (Al3+,VI+Al3+,IV <-> (Fe2+ 또는 Mg2+)VI+(Si4+)IV).

Occurrence and Chemical Composition of White Mica and Chlorite from Laminated Quartz Vein of Unsan Au Deposit (운산 금 광상의 엽리상 석영맥에서 산출되는 백색운모와 녹니석의 산상 및 화학조성)

  • Yoo, Bong Chul
    • Korean Journal of Mineralogy and Petrology
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    • v.34 no.1
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    • pp.1-14
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    • 2021
  • The Unsang gold deposit has been one of the three largest deposits (Daeyudong, Kwangyang) in Korea. The geology of this deposit consists of series of host rocks including Precambrian metasedimentary rock and Jurassic Porphyritic granite. The deposit consists of Au-bearing quartz veins which filled fractures along fault zones in Precambrian metasedimentary rock and Jurassic Porphyritic granite, which suggests that it is an orogenic-type deposit. Quartz veins are classified as 1) galena-quartz vein type, 2) pyrrhotite-quartz vein type, 3) pyrite-quartz vein type, 4) pegmatic quartz vein type, 5) muscovite-quartz vein type and 6) simple quartz vein type based on mineral assembles. The studied quartz vein is pyrite-quartz vein type which occurs as sericitization, chloritization and silicification. The white mica from stylolitic seams of laminated quartz vein occurs as fine or medium aggregate associated with white quartz, pyrite, chlorite, rutile, monazite, apatite, K-feldspar, zircon and calcite. The structural formular of white mica from laminated quartz vein is (K0.98-0.86Na0.02-0.00Ca0.01-0.00Ba0.01-0.00 Sr0.00)1.00-0.88(Al1.70-1.57Mg0.22-0.09Fe0.23-0.10Mn0.00Ti0.04-0.02Cr0.01-0.00V0.00Ni0.00)2.06-1.95 (Si3.38-3.17Al0.83-0.62)4.00O10(OH2.00-1.91F0.09-0.00)2.00. It indicated that white mica of laminated quartz vein has less K, Na and Ca, and more Si than theoretical dioctahedral micas. Compositional variations in white mica from laminated quartz vein are caused by phengitic or Tschermark substitution [(Al3+)VI+(Al3+)IV <-> (Fe2+ or Mg2+)VI+(Si4+)IV] and direct (Fe3+)VI <-> (Al3+)VI substitution. The structural formular of chlorite from laminated quartz vein is((Mg1.11-0.80Fe3.69-3.14Mn0.01-0.00Zn0.01-0.00K0.07-0.01Na0.01-0.00Ca0.04-0.01Al1.66-1.09)5.75-5.69 (Si3.49-2.96Al1.04-0.51)4.00O10 (OH)8. It indicated that chlorite of laminated quartz vein has more Si than theoretical chlorite. Compositional variations in chlorite from laminated quartz vein are caused by phengitic or Tschermark substitution (Al3+,VI+Al3+,IV <-> (Fe2+ or Mg2+)VI+(Si4+)IV) and octahedral Fe2+ <-> Mg2+ (Mn2+) substitution. Therefore, laminated quartz vein and alteration minerals of the Unsan Au deposit was formed during ductile shear stage of orogeny.

Properties of Oxide Systems for NTC Thermistors (산화물계 NTC 서미스터의 특성)

  • Lee, Sung-Kwan;Lee, Hae-Yon;Lee, Sean-Hag;Her, Jeong-Seob;Kim, Hyun-Sik;Oh, Young-Woo
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1855-1857
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    • 1999
  • $Mn_{1-x}Fe_{2+x}O_4$, $Mg_{1-x}Fe_{2+x}O_4$ (x=0.0, 0.025, 0.1, 0.2) for negative temperature coefficient (NTC) thermistor were prepared by calcining at $800^{\circ}C$ and sintering from 1100 to $1250^{\circ}C$ with $50^{\circ}C$ intervals. The best linear property was obtained in the Mn-based sample sintered at $1200^{\circ}C$ with x=0.0 composition. Temperature coefficient of resistance, $\alpha$, was -3.0 %/$^{\circ}C$ in the Mg-based sample at $25^{\circ}C$. Thermistor parameter, B, was in the range of 2500 [K] $\sim$7400 [K]. The results show the possibility that Mn-Ni-Co based thermistor could be substituted by the composition used in this study.

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Bending Properties of the Flexible BMNO (Bi2Mg2/3Nb4/3O7) Capacitor Using Graphene Electrode (그래핀 전극을 이용한 유연한 BMNO (Bi2Mg2/3Nb4/3O7) 캐패시터의 굽힘 특성)

  • Song, Hyun-A;Park, Byeong-Ju;Yoon, Soon-Gil
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.5
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    • pp.387-391
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    • 2012
  • Graphene was fabricated onto Ni/Si substrate using a rapid-thermal pulse CVD and they were transferred onto the Ti/PES flexible substrate. For top electrode applications of the BMNO dielectric films, graphene was patterned using a argon plasma. Through an AFM image and a leakage current density of the BMNO films grown onto various bottom electrodes before and after bending test, BMNO films grown onto the graphene bottom electrode showed no change of the microstructure and the leakage current density after the bend.

Ion Exchange Recovery of Rhenium and Its Determination in Aqueous Solutions by Diffuse Reflection Spectroscopy

  • Kalyakina, O.P.;Kononova, O.N.;Kachin, S.V.;Kholmogorov, A.G.
    • Bulletin of the Korean Chemical Society
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    • v.25 no.1
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    • pp.79-84
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    • 2004
  • The existing technological schemes for processing rhenium-containing raw materials involve the recovery of Re from solutions, which can be effectively achieved by anion exchange method. The application of anion exchange also allows to study rhenium state in aqueous solutions and to develop analytical control methods. The present work is focused on investigation of ion exchange equilibrium in the analytical system Re(VII)-HCl-$SnCl_2$-KSCN-anion exchanger by means of sorption-desorption method as well as by electron, IR- and diffuse reflection spectroscopy. It was shown that rhenium can be quantitatively recovered from this system. It is proposed to use the sorption-spectroscopic method for Re(VII) determination in aqueous solutions. The calibration curve is linear in the concentration range of 0.5-20.0 mg/L (sample volume is 25.0 mL) and the detection limit is 0.05 mg/L. The presence of Mo(VI), Cu(II), Fe(II, III), Ni(II), Zn(II) as well as $K^+,\;Na^+$ do not hinder the solid-phase determination of rhenium. Rhenium (VII) determination by diffuse reflection spectroscopy was carried out in model solutions as well as in samples of river-derived water and in solutions obtained after the dissolution of spent catalysts.

Seasonal Variation and Statistical Analysis of Particulate Pollutants in Urban Air (도시대기립자상물질중 오염성분의 계절적 변동 및 통계적 해석)

  • 이승일
    • Journal of environmental and Sanitary engineering
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    • v.9 no.2
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    • pp.8-23
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    • 1994
  • During the period from Mar., 1991 to Feb., 1992 66 tSP samples were collected by Hi volume air sampler at 1 sampling site in Seoul and the amount of concentration of 21 components(SO$_{4}$$^{2-}$, NO$_{3}$$^{-}$, NH$_{4}$$^{+}$, Cl$^{-}$, Al, Ba, Ca, Cd, Cr, Cu, Fe, It Mg, Mn, Na, Ni, Pt Si, Ti, Zn, Zr ) were measured. And monthly and seasonal variation were surveyed and the principal component analysis( PCA ) were carried out with respect to these amount of pollutants, minimum of visibility and radiation on a horizontal surface. The total amount of soluble ion in water was high in order o(SO$_{4}$$^{2-}$> NO$_{3}$$^{-}$> N%'>Cl$^{-}$ and metal ion was high in order of Na> Ca>Si> Fe> Al> K> Mg> Zn> Pb> Cu>Ti> Mn > Ba> Cr> Zr> Ni> Cd. There was Seasonal variation in concentration for SO$_{4}$$^{2-}$, NH$_{4}$$^{+}$, Cl$^{-}$, Na, Al, Ca, Bt Mg, Fe and Si. It was assumed that the components of the highest concentration on April were depend on yellow sand and the frequency of wind velocity and direction. As the results of PCA, the amount of pollution components was able to characterized with two principal components(Z$_{1}$, Z$_{2}$ ). The first principal components Z$_{1}$ was considered to be a factor indicating the pollutants originated from natural generation and The second principal components Z$_{2}$ was considered to be a factor indicating the pollutants originated from human work. The monthly concentration of pollutants in ISP, minimum of visibility and radiation on a horizontal surface was possible to evaluate by the use of these two principal components Z$_{1}$ and Z$_{2}$ .

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Design and Acoustic Properties of Acoustic Device with Metal-Piezoceramic Circular Plate (금속-압전세라믹스로 구성된 음향소자의 설계 및 음향특성)

  • Go Young-Jun;Lee Sang-Wook;Nam Hyo-Duk;Chang Ho-Gyeong
    • Proceedings of the Acoustical Society of Korea Conference
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    • spring
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    • pp.275-278
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    • 2000
  • In this study, the acoustic transducer of a thin circular disc-type with PZT/Metal was designed. The dielectric and piezoelectric properties of $0.5wt\%$ $MnO_2$ and NiO doped 0.1Pb($Mg_{1/3}$$Nb_{2/3}$)$O_3$-$0.45PbTiO_3$-$0.45PbZrO_3$ ceramics were investigated aiming at acoustic transducer applications. The vibration characteristics for the laminated circular plate was analyzed for the various thickness and diameter of the piezoceramic layer and metal layer. The acoustic characteristics which is radiated from the acoustic transducer within the finite space was simulated using the finite element method. It has been observed that the characteristics of the sound pressure ard impedance response calculated for the various models of the size and geometry of acoustic transducer.

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Suppression of Charge Recombination Rate in Nanocrystalline SnO2 by Thin Coatings of Divalent Oxides in Dye-Sensitized Solar Cells

  • Lee, Chae-Hyeon;Lee, Gi-Won;Kang, Wee-Kyung;Lee, Doh-Kwon;Ko, Min-Jae;Kim, Kyoung-Kon;Park, Nam-Gyu
    • Bulletin of the Korean Chemical Society
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    • v.31 no.11
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    • pp.3093-3098
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    • 2010
  • The core-shell $SnO_2$@AO (A=Ni, Cu, Zn and Mg) films were prepared and the effects of coatings on photovoltaic properties were investigated. Studies on X-ray photoelectron spectroscopy, energy dispersive X-ray analysis and transmission electron microscopy showed the formation of divalent oxides on the surface of $SnO_2$ nanoparticles. It was commonly observed that all the dye-sensitized core-shell films exhibited higher photovoltage than the bare $SnO_2$ film. Transient photovoltage measurements confirmed that the improved photovoltages were related to the decreased time constants for electron recombination.