• Title/Summary/Keyword: NiGe

Search Result 69, Processing Time 0.029 seconds

Phase Evolution in LiMO2(M=Co,Ni) Cathode Materials for Secondary Lithium Ion Batteries : Effect of Temperature and Oxygen Partial Pressure (리튬 2차 전지용 양극활물질 LiMO2(M=Co,Ni)의 온도와 산소 분압에 따른 상전이 거동)

  • Huang, Cheng-Zhu;Kim, Ho-Jin;Jeong, Yeon-Uk;Lee, Joon-Hyung;Kim, Jeong-Joo
    • Journal of the Korean Ceramic Society
    • /
    • v.42 no.4
    • /
    • pp.292-297
    • /
    • 2005
  • $LiMO_{2}(M=Co,Ni)$ samples were synthesized with $Li_{2}CO_{3},\;Co_{3}O_{4}$, and NiO by the solid-state reaction method. In the case of $LiCoO_{2}$, at low temperature$(T=400^{\circ}C)$ spinel structure was synthesized and the obtained spinel phase was transformed to layered phase at high temperature$(T\ge600^{\circ}C)$. The phase transition behaviors of $LiCoO_{2}$ were investigated with various heating temperature and time. The rate of transition was directly proportional to the concentrations of reactant, and activation energy of reaction was around 6.76 kcal/mol. When CoO(rock salt structure) was used as a starting material instead of $Co_{3}O_{4}$(spinel structure), layered structure of $LiCoO_{2}$ was obtained at low temperature. In the case of $LiNiO_{2}$ the transition from layered structure to rock salt structure occurred easily by disordering/ordering reaction, but did not occur in $LiCoO_{2}$. The difference in metal ion radii in $LiCoO_{2}$ and $LiNiO_{2}$ results in different behaviors of phase transitions.

Stepwise Ni-silicide Process for Parasitic Resistance Reduction for Silicon/metal Contact Junction

  • Choi, Hoon;Cho, Il-Whan;Hong, Sang-Jeen
    • Transactions on Electrical and Electronic Materials
    • /
    • v.9 no.4
    • /
    • pp.137-142
    • /
    • 2008
  • The parasitic resistance is studied to silicon/metal contact junction for improving device performance and to lower contact/serial resistance silicide in natural sequence. In this paper constructs the stepwise Ni silicide process for parasitic resistance reduction for silicon/metal contact junction. We have investigated multi-step Ni silicide on SiGe substrate with stepwise annealing method as an alternative to compose more thermally reliable Ni silicide layer. Stepwise annealing for silicide formation is exposed to heating environment with $5^{\circ}C/sec$ for 10 seconds and a dwelling for both 10 and 30 seconds, and ramping-up and the dwelling was repeated until the final annealing temperature of $700\;^{\circ}C$ is achieved. Finally a direct comparison for single step and stepwise annealing process is obtained for 20 nm nickel silicide through stepwise annealing is $5.64\;{\Omega}/square$ at $600\;^{\circ}C$, and it is 42 % lower than that of as nickel sputtered. The proposed stepwise annealing for Ni silicidation can provide the least amount of NiSi at the interface of nickel silicide and silicon, and it provides lower resistance, higher thermal-stability, and superior morphology than other thermal treatment.

Neutron Diffraction Study of Powders Prepared by Self-propagating High Temperature Synthesis

  • Park, Yong;Kim, Y S.;Y. D. Hahn;S. H. Shim;Lee, J. S.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
    • /
    • 2000.11a
    • /
    • pp.11-12
    • /
    • 2000
  • Non-stoichiometric ceramics of $Ni_{x}ZnO_{1-x}Fe_{2}O_{4}$ were prepared by self-propagating high temperature synthesis reaction with various processing conditions and their stoichometric numbers were determined by neutron diffraction. The neutron diffraction patterns were measured at room temperature using monochromatic neutrons with a wave length of 0.18339 nm from a Ge(331) mocochromator at a 90 degree take off angle. The Rietveld refinement of each pattern converged to good agreement (x2=1.88-2.24). The neutron diffraction analysis revealed the final stoichiometries of the ferrites were $Ni_{0.38}Zn_{0.62}Fe_{2}O_{4}$ and $Ni_{0.33}Zn_{0.67}Fe_{2}O_{4]$, respectively. This supports that final stoichiometric number of the self-propagating high temperature synthesis product can be controlled by the processing parameters during the combustion reaction.

  • PDF

Evaluations of Si based ternary anode materials by using RF/DC magnetron sputtering for lithium ion batteries

  • Hwang, Chang-Muk;Park, Jong-Wan
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2010.08a
    • /
    • pp.302-303
    • /
    • 2010
  • Generally, the high energy lithium ion batteries depend intimately on the high capacity of electrode materials. For anode materials, the capacity of commercial graphite is unlike to increase much further due to its lower theoretical capacity of 372 mAhg-1. To improve upon graphite-based negative electrode materials for Li-ion rechargeable batteries, alternative anode materials with higher capacity are needed. Therefore, some metal anodes with high theoretic capacity, such as Si, Sn, Ge, Al, and Sb have been studied extensively. This work focuses on ternary Si-M1-M2 composite system, where M1 is Ge that alloys with Li, which has good cyclability and high specific capacity and M2 is Mo that does not alloy with Li. The Si shows the highest gravimetric capacity (up to 4000mAhg-1 for Li21Si5). Although Si is the most promising of the next generation anodes, it undergoes a large volume change during lithium insertion and extraction. It results in pulverization of the Si and loss of electrical contact between the Si and the current collector during the lithiation and delithiation. Thus, its capacity fades rapidly during cycling. Si thin film is more resistant to fracture than bulk Si because the film is firmly attached to the substrate. Thus, Si film could achieve good cycleability as well as high capacity. To improve the cycle performance of Si, Suzuki et al. prepared two components active (Si)-active(Sn, like Ge) elements film by vacuum deposition, where Sn particles dispersed homogeneously in the Si matrix. This film showed excellent rate capability than pure Si thin film. In this work, second element, Ge shows also high capacity (about 2500mAhg-1 for Li21Ge5) and has good cyclability although it undergoes a large volume change likewise Si. But only Ge does not use the anode due to its costs. Therefore, the electrode should be consisted of moderately Ge contents. Third element, Mo is an element that does not alloys with Li such as Co, Cr, Fe, Mn, Ni, V, Zr. In our previous research work, we have fabricated Si-Mo (active-inactive elements) composite negative electrodes by using RF/DC magnetron sputtering method. The electrodes showed excellent cycle characteristics. The Mo-silicide (inert matrix) dispersed homogeneously in the Si matrix and prevents the active material from aggregating. However, the thicker film than $3\;{\mu}m$ with high Mo contents showed poor cycling performance, which was attributed to the internal stress related to thickness. In order to deal with the large volume expansion of Si anode, great efforts were paid on material design. One of the effective ways is to find suitably three-elements (Si-Ge-Mo) contents. In this study, the Si based composites of 45~65 Si at.% and 23~43 Ge at.%, and 12~32 Mo at.% are evaluated the electrochemical characteristics and cycle performances as an anode. Results from six different compositions of Si-Ge-Mo are presented compared to only the Si and Ge negative electrodes.

  • PDF

The Effect of Electrode Pattern on the Humidity-sensing Properties of the Resistive Humidity Sensor Based on All-printing Process (인쇄공정으로 제조된 저항형 습도센서의 감습특성에 대한 전극패턴의 영향 연구)

  • Ahn, Hee-Yong;Gong, Myoung-Seon
    • Polymer(Korea)
    • /
    • v.36 no.2
    • /
    • pp.169-176
    • /
    • 2012
  • Based on our experience in developing resistive humidity sensor, interdigital gold electrodes with different fingers and gaps have been fabricated on a glass epoxy (GE) substrate using screen printing techniques. The basic structure of the electrode consisted of a 3-, 4- and 5-fingers with gaps of 310 and 460 ${\mu}m$. Gold electrode/GE was prepared by first printing silver nanopaste, followed by consecutive electroless plating of Cu, Ni and then Au. Copolymer of [2-(methacryloyloxy)ethyl] dimethyl benzyl ammonium chloride (MDBAC) and methyl methacrylate (MMA) was used as a humidity-sensing polyelectrolyte, which was fabricated by a screen printing method on the Au electrode/GE substrate. The flexible humidity sensor showed acceptable linearity between logarithmic impedance and relative humidity in the range of 20-95%RH, low hysteresis of 1.5%RH, good response and recovery time of 75 sec at 1 V, 1 kHz, and $25^{\circ}C$. Electrode construction had a significant influence on the humidity-sensing characteristics of polymeric humidity sensors. The activation energy between electrode and ion conducting polyelectrolyte plays an important role in explaining the differences of humidity sensing characteristics such as temperature dependence, sensitivity, linearity and hysteresis.

Thermal Stability Improvement of Nickel-Silicide using PAI in the N-type Substrate (N-type 기판에서 PAI에 의한 Nickel-Silicide의 열안정성 개선)

  • 윤장근;지희환;오순영;배미숙;황빈봉;박영호;왕진석;이희덕
    • Proceedings of the IEEK Conference
    • /
    • 2003.07b
    • /
    • pp.675-678
    • /
    • 2003
  • 본 논문에서는 N-type 기판에서 Nickel-Silicide를 적용하였을 경우에 나타나는 문제점과 PAI (Pre-amorphization Implant)의 효과에 대하여 알아보았다. N-type 기판에 RTP (Rapid Thermal Process)를 통하여 Nickel-Silicide 를 형성하게 되는데, 여기까지는 안정한 Nickel mono-Silicide (NiSi)가 형성됨을 확인하였다. 하지만 후속 열처리 공정 후 심한 응집 현상 (Agglomeration)과 이상 산화 현상 (Abnormal Oxidation Phenomenon), Silicide Island 등 열안정성 (Thermal Stability) 측면에서 여러 가지 많은 문제점들이 나타났다. 이 후속 열처리의 열안정성 취약점들을 극복하는 방안으로 Ge 및 N₂ PAI를 적용하였다. PAI를 적용하였을 경우에는 그렇지 않은 경우에 비하여 고온 열처리 후에도 면저항이 비교적 잘 유지되었으며, 두께가 얇고 안정한 Nickel-Silicide 특성을 확보할 수 있었다. 특히 Ge PAI 에 비하여 N₂ PAI 의 경우가 보다 특성 개선 효과가 크게 나타났다.

  • PDF

Co-interlayer와 $SiO_2$ 상부막의 유무에 따른 Nickel Germanosilicide의 열안정성 연구

  • 조유정;한길진;오순영;김용진;이원재;이희덕;김영철
    • Proceedings of the Korean Society Of Semiconductor Equipment Technology
    • /
    • 2005.05a
    • /
    • pp.215-218
    • /
    • 2005
  • Co-interlayer와 $SiO_2$ 상부막이 nickel germanosilicide 박막의 열안정성에 미치는 영향을 연구하였다. Nickel germanosilicide는 SiGe 기판 위에 Ni(8nm)/TiN(25nm), Ni(6m)/Co(2nm)/TiN(25nm)을 증착하여 각각 one step RIP($500^{\circ}C$)와 two step RTP(500. $700^{\circ}C$)로 형성되었다. 50과 10nm 두께의 $SiO_2$ 박막을 실리사이드 위에 증착하고, 550, 600, $650^{\circ}C$에서 30분간 열처리한 후 면저항 값을 측정하여 열안정성을 평가하였다.

  • PDF

Microstructure and Bonding Strength of Tungsten Coating Deposited on Copper by Plasma Spraying

  • Song, Shu-Xiang;Zhou, Zhang-Jian;Du, Juan;Zhong, Zhi-Hong;Ge, Chang-Chun
    • Proceedings of the Korean Powder Metallurgy Institute Conference
    • /
    • 2006.09a
    • /
    • pp.511-512
    • /
    • 2006
  • Tungsten coatings with different interlayers onto the oxygen-free copper substrates were fabricated by atmosphere plasma spraying. The effects of different interlayers of NiCrAl, NiAl and W/Cu on bonding strength were studied. SEM, EDS and XRD were used to investigate the photographs and compositions of these coatings. The tungsten coatings with different initial particle sizes resulted in different microstructures. Oxidation was not detected in the tungsten coating, but in the interlayer, it was found by both XRD and EDS. The tungsten coating deposited directly onto the copper substrate presented higher bonding strength than those with different interlayers.

  • PDF