• 한국재료학회지
• /
• 제12권4호
• /
• pp.274-278
• /
• 2002

Discrete-variational(DV)-$X{\alpha}$ method was applied to investigate the electronic structures of spinel- type manganese oxide which is well known to the high performance adsorbent or cathode material for lithium ion. The results of DOS(density of states) and Mulliken population analysis showed that Li was nearly fully ionized and interactions between Mn and O were strong covalent bond. The effective charge of Li and Mn was +0.77 and +1.44 respectively and the overlap population between Mn and O was 0.252 in $LiMn_2O_4$. These results from DV-X$\alpha$ method were well coincided with the experimental result by XPS analysis and supported the feasibility of theoretical interpretation for the $LiMn_2O_4$ compound.

• Bulletin of the Korean Chemical Society
• /
• 제34권4호
• /
• pp.1199-1204
• /
• 2013

Nanocomposites consisting of Sn nanoparticles and graphene oxide (GO) were electrophoretically deposited onto Cu current collectors that was used for anodes in Li ion batteries (LIBs). In order to optimize the electrochemical performance of nanocomposites as an anode material by controlling the oxygen functionality, the GO was subjected to $O_3$ treatment prior to electrophoretic deposition (EPD). During thermal reduction of the GO in the nanocomposites, the Sn nanoparticles were reduced in size, along with the formation of SnO and/or $SnO_2$ at a small fraction, relying on the oxygen functionalities of the GO. The variation in the duration of time for the $O_3$ irradiation resulted in a small change in total oxygen content, but in a significantly different fraction of each functional group in the GO, which influenced the Sn nanoparticle size and the amount of SnO (and/or $SnO_2$). As a result, the EPD films prepared with the GO that possessed the least amount of carboxylic groups (made by treating GO in an $O_3$ environment for 3 h) showed the best performance, when compared with the nanocomposites composed of untreated GO or GO that was $O_3$-treated for a duration of less than 3 h.

• Bulletin of the Korean Chemical Society
• /
• 제30권8호
• /
• pp.1733-1737
• /
• 2009

A new cathode material based on Li$Ni_{0.8}Co_{0.15}Al_{0.05}O_2$ (LNCA)/polyaniline (Pani) composite was prepared by in situ self-stabilized dispersion polymerization in the presence of LNCA. The materials were characterized by fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrochemical properties including galvanostatic charge-discharge ability, cyclic voltammetry (CV), capacity, cycling performance, and AC impedance were measured. The synthesized LNCA/Pani had a similar particle size to LNCA and exhibited good electrochemical properties at a high C rate. Pani (the emeraldine salt form) interacts with metal-oxide particles to generate good connectivity. This material shows good reversibility for Li insertion in discharge cycles when used as the electrode of lithium ion batteries. Therefore, the Pani coating is beneficial for stabilizing the structure and reducing the resistance of the LNCA. In particular, the LNCA/Pani material has advantageous electrochemical properties.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
• /
• pp.189-189
• /
• 2000

고분자 재료에 이온을 주입함으로서 경도, 내마모, 내피로성의 기계적인 특성과 내부식성 등의 화학적 특성이 향상되며, 표면 전기전도도와 광학밀도(optical density)가 변한다. 본 연구에서는 MPPO(Modified-Polyphenlene Oxide) 표면에 N2, Ar, Xe 이온을 에너지 50keV, 선량(dose)을 1$\times$1015에서 1$\times$1017ions/cm2로 증가시키면서 조사하였다. 이온 조사량의 증가에 따라 표면 저항이 2$\times$1015에서 6$\times$106($\Omega$/$\square$)으로 감소하여 표면 전기전도도가 향상되었다. Ar 이온은 1016ion/cm2이하의 조사량(dose)에서 N2보다 표면 저항을 더 많이 감소하는데 반해 1016ion/cm2 이상의 조사량에서는 Ar과 N2의 표면 저항이 비슷한 값을 나타냈다. Xe은 Ar과 N2이온에 비하여 전체적으로 표면저항이 많이 감소하여 전도도의 향상은 Xe, Ar, N2 순서로 질량이 큰 이온이 조사 효과가 큰 것으로 나타났다. 소재 표면은 SIMS 분석을 통하여 깊이에 따른 주입이온의 분포를 관찰하였으며, 표면 색상은 황색에서 갈색을 거쳐 암갈색으로 변화함으로서 가시광선에 대한 반사율(reflectance)이 감소하고 광학밀도(optical density)가 증가하여 광학적 특성이 변하였다. 이온 주입 후 에너지 전이에 의한 효과는 optical gap를 감소시켜 광학밀도(optical density)와 표면 전기 전도도를 증가시킨다. 이에 따라 본 논문에서는 이온주입에 의한 광학적, 전기적 특성간의 상관관계를 밝히고자 한다.

• 자원리싸이클링
• /
• 제10권3호
• /
• pp.23-28
• /
• 2001

Magnetite가 주성분인 산화철 폐촉매를 이용하여 도금폐수중 아연이온을 pH 2.0이상에서 98.7% 이상 회수하였다. 폐촉매의 포화자화값은 59.4 smug으로 폐수처리후 자기적방법에 의해 고.액분리가 가능하다. 산화철 .폐촉매에 의한 폐수중 아연이온의 회수메카니즘은 pH 3.0-8.5 범위에서는 폐촉매 표면에서 $Zn^{2+}$ 이온의 정전기적 흡착이며 pH 8.5 이상에서는 $Zn(OH)_2$의 침전이라고 생각한다.

• Transactions on Electrical and Electronic Materials
• /
• 제14권4호
• /
• pp.216-220
• /
• 2013

The etching characteristics of indium zinc oxide (IZO) in $Cl_2/Ar$ plasma were investigated, including the etch rate and selectivity of IZO. The IZO etch rate showed non-monotonic behavior with increasing $Cl_2$ fraction in the $Cl_2/Ar$ plasma, and with increasing source power, bias power, and process pressure. In the $Cl_2/Ar$ (75:25%) gas mixture, a maximum IZO etch rate of 87.6 nm/min and etch selectivity of 1.09 for IZO to $SiO_2$ were obtained. Owing to the relatively low volatility of the by-products formation, ion bombardment was required, in addition to physical sputtering, to obtain high IZO etch rates. The chemical state of the etched surfaces was investigated with X-ray photoelectron spectroscopy. These data suggested that the IZO etch mechanism was ion-enhanced chemical etching.

• 한국전기전자재료학회논문지
• /
• 제15권7호
• /
• pp.576-582
• /
• 2002

Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectrics were fabricated, and nitrogen distribution and bonding species which contribute to memory characteristics were analyzed. Also, memory characteristics of devices depending on the anneal temperatures were investigated. The devices were fabricated by retrograde twin well CMOS processes with $0.35\mu m$ design rule. The processes could be simple by in-situ process in growing dielectric. The nitrogen distribution and bonding states of gate dielectrics were investigated by Dynamic Secondary Ion Mass Spectrometry(D-SIMS), Time-of-Flight Secondary Ion Mass Spectrometry(ToF-SIMS), and X-ray Photoelectron Spectroscopy(XPS). As the nitridation temperature increased, nitrogen concentration increased linearly, and more time was required to form the same reoxidized layer thickness. ToF-SIMS results showed that SiON species were detected at the initial oxide interface which had formed after NO annealing and $Si_2NO$ species within the reoxidized layer formed after reoxidation. As the anneal temperatures increased, the device showed worse retention and degradation properties. It could be said that nitrogen concentration near initial interface is limited to a certain quantity, so the excess nitrogen is redistributed within reoxidized layer and contribute to electron trap generation.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.339.1-339.1
• /
• 2014

In this paper we studied the application of inter-poly dielectric as silicon dioxide-like film was deposited by the higher energy assisting deposition (HEAD) process the modified CCP process, which enables low temperature (LT) process and improving film density. In these experiments the relative hydrogen concentration of $SiO_2$-like films deposited on silicon substrate were analyzed by the secondary ion mass spectroscopy (SIMS) and it was shown that our lower hydrogenated oxide (LHO) film prepared by HEAD process with the precursor contained the siloxane species had lower hydrogen concentration, $8{\times}10{\cdot}^{22}cm{\cdot}^3$ than that of the commercial undoped silicon glass (USG) film ($1{\times}10{\cdot}^{21}cm{\cdot}^3$) prepared by the high density plasma-chemical vapor deposition (HDP-CVD). We consider that the LHO film deposited by HEAD process used as high performance material into Flash memory devices.

• 한국표면공학회지
• /
• 제30권4호
• /
• pp.223-230
• /
• 1997

Tungsten oxide and nickel oxide thin films were deposited onto ITO(Indium Tin Oxide) transparent glass by the E-beam evaporation and were used as a cathode and an anode for the EC(Electrochromic) smart window, respectively. Stoichiometric structures of the deposited films were investigated by the implementation of XPS(X-ray Photoelectron Spectroscopy) analysis and the results were $WO_{2.42}$ and $NiO_{0.44}$. This oxygen deficincy might affect affect the transparency of the thin films. The electrolyte for the EC smart windows was PAN-$LiCIO_4$ conducting polymer. EC(Ethylene Carbonate)and PC(Propylene Carbonate) were added as plasticizer to enhance ion conductivity. When the weight ratio of the EC : PC was 3 : 1, transmission difference and cycle life performance were tested. Polymer EC windows showed 40% $\Delta$T at 1.5V operating volage for 3,200 cycles. Structural degradation was observed by the SIMS(Secondary Ion Mass Spectroscopy) analysis and it was confirmed that structural degradation of polymer caused by the solvent evaporation was the main cause to degrade EC smart windows.

• 전기화학회지
• /
• 제18권3호
• /
• pp.95-101
• /
• 2015

본 논문에서는 차세대 고용량 양극 물질로 각광받고 있는 리튬리치계 산화물의 나노입자의 제조방법에 대해 보고하고 있다. 리튬리치계 산화물은 기존에 사용되고 있는 $LiCoO_2$와 같은 양극물질의 50-80% 이상 높은 용량으로 인해 고용량 이차전지용 양극재료로 기대를 받고 있다. 그러나 이온 및 전자전도성이 좋지 못하여 고율특성이 취약한 단점이 있다. 본 연구에서는 리튬리치계 산화물을 나노입자화 하여 고율특성을 향상시키는데 연구의 초점을 맞추고 있다. 이를 위해 제조공정에서 2가지 계면활성제를 사용, 입자를 분산시켜 나노화 하였다. 나노 입자를 가진 리튬리치 산화물의 전기화학적 특성을 관찰한 결과 상대적으로 우수한 고율특성을 가지고 있음을 확인할 수 있었다.