• Applied Chemistry for Engineering
• /
• v.2 no.4
• /
• pp.311-329
• /
• 1991

Electrochemical behavior of surface active Osmium bipyridine complex adsorbed in a monomolecular layer on tin oxide electrodes by the Langmuir-Blodgett method was studied. Theoretical equation of cyclic voltammetry of electrode reactions for redox species adsorbed as monolayer form was discussed by reversible and quasi-reversible waves. The film was transferred onto the $SnO_2$ electrode surface and then amounts of charge on the electrode were measured in the technique of cyclic voltammetry. The electron transfer mediation of these monolayer with $Fe^{2+}$, TEMPOL and others were studied. And the cyclic voltammetry were simulated by taking into account the interaction parameters. From these values, we found it possible to fit almost all measured cyclic voltammograms with these parameters. The recent works and directions using LB method were introduced with various applicable field.

• Journal of the Korean Vacuum Society
• /
• v.4 no.1
• /
• pp.85-90
• /
• 1995

본 연구에서는 투명 전극으로의 응용을 목적으로 PECVD법에 의해 증착된 B이 첨가된 ZnO 박막의 전기 및 광학적 특성을 살펴보았다. B을 첨가하지 않은 ZnO 박막은 비저항이 수 $\Omega$-cm 정도의 값을 가지고 있었으며 시간에 따른 비저항의 변화가 컸으나, 2% B2H6을 5-16sccm의 유량범위에서 첨가한 경우에는 5-9X10-2 $\Omega$-cm의 비저항을 가지고 시간 경과에 따른 비저항의 변화가 아주 작은 ZnO 박막을 얻을 수 있었다. Van der Pauw법에 의한 Hall 계수의 측정 결과에 의하면, B을 첨가하지 않은 ZnO 박막의 전자 농도는 1017/㎤정도였으나 B을 첨가함으로써 최고 1020/㎤까지 증가하였다. 그러나 B이 첨가되기 전에는 박막의 전하 나르게 이동도가 $4extrm{cm}^2$/V.sec 이었으나, B참가에 의해 $0.7\textrm{cm}^2$/V.sec 이하로 감소하였다. B을 첨가한 경우와 첨가하지 않은 경우의 ZnO 박막은 모두 가시광성영역에서 90%이상의 광투과율을 가지고 있었으며, B을 첨가한 경우는 전자농도가 증가함에 따라 광학적 밴드 갭이 3.3eV로부터 3.55eV로 증가하는 거동을 보였다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.496-496
• /
• 2013

스마트윈도우는 디스플레이, 산업용 외장재 등 다양한 분야에 응용이 가능하며, 특히 전기변색을 이용한 디바이스는 나노코팅 기술을 통한 나노입자 및 나노가공제어 등 나노융합기술을 접목할 수 있다. 전기변색 디바이스는유리 또는 필름 기판소재를 통해 제작이 가능하며, 본 연구에서는 전기변색의 산화, 환원반응에 의해 재료의 광특성이 가역적으로 변화할 수 있는 물질을 증착하여 기존 라미네이터 및 Sol-Gel방식의 전해질보다 열화현상에의한 성능저하를 막아주는 박막전해질 코팅 연구이다. 전기변색 소자는 외부 인가 전압(external voltage)에 의해 유도된 전하의 주입(injection) 과 추출(extraction)을 통하여 그 광학적 특성(optical property)을 가역적으로(reversibly) 변 화시킬 수 있는 특징을 가지고 있다. 전기변색소재의 원리를 간략하게 설명하면 대표적인 환원착색 물질인 전기변색층(WO, MoO, Nb2O5 등)으로 Li+ 또는 H+과 전자가 주입되면 전기변색되고 방출 시는 투명하게 되며, 반대로산화착색 물질인(V2O5, NiO, IrO, MnO 등)으로 Li+ 또는 H+과 전자가 방출되면 변색되고 주입되면 투명하게 되는 것이다. 본 연구에서는 전자가 주입되는 환원착색물질인 WO와 함께 Ta2O5박막을 증착하여 광학적특성을 연구하고 박막의 두께 및 전압인가에따른 변색 및 응답속도를 연구하고자 한다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.252-252
• /
• 2011

최근 주목받고 있는 amorphous gallium-indium-zinc-oxide (a-GIZO) thin film transistors (TFTs)는 수소가 첨가된 비정질 실리콘 TFT에 비해 높은 이동도와 뛰어난 전기적, 광학적 특성에 의해 큰 주목을 받고 있다. 또한 넓은 밴드갭을 가지므로 가시광 영역에서 투명한 특성을 보이고, 플라스틱 기판 위에서 구부러지는 성질에 의해 플랫 패널 디스플레이나 능동 유기 발광소자 (AM-OLED), 투명 디스플레이에 응용되고 있다. 뿐만 아니라, 일반적인 Poly-Si TFT는 자체적으로 가지는 결정성에 의해 대면적화 시 균일성이 좋지 못하지만 GIZO는 비정질상 이기 때문에 백플레인의 대면적화에 유리하다는 장점이 있다. 이러한 TFT를 제작하기 전, 전기적 특성에 대한 정보를 얻거나 예측하는 것이 중요한데, 이에 따라 고안된 구조가 바로 metal point contact FET (pseudo FET)이다. pseudo FET은 소스/드레인 전극을 따로 증착할 필요 없이 채널을 증착한 후, 프로브 탐침을 채널의 표면에 적당한 압력으로 접촉시켜 전하를 공급하는 소스와 드레인처럼 동작시킬 수 있다. 따라서 소스/드레인을 증착하거나 lithography와 같은 추가적인 공정을 요구하지 않아 소자의 특성을 보다 간단하고 수월하게 분석할 수 있다는 장점이 있다. 본 연구에서는 p-type 기판위에 100nm의 oxidation SiO2를 게이트 절연막으로 사용하는 a-GIZO pseudo FET를 제작하였다. 소자 제작 후, 열처리 온도에 따른 전기적 특성을 분석하였고, 열처리 조건은 30분간 N2 분위기에서 실시하였다. 열처리 후 전기적 특성 분성 결과, 450oC에서 가장 낮은 subthreshold swing 값과 게이트 전압의 더블 스윕 후 문턱 전압의 변화가 거의 없음을 확인하였다.

• Journal of the Korean Chemical Society
• /
• v.36 no.1
• /
• pp.51-56
• /
• 1992

X-ray diffraction analysis and infrared spectrophotometry were used to investigate the crystal structures and the bonding characteristics in $Pb(Zr_{1-y}Ti_y)O_3$ (PNZT), which has a perovskite structure. As $Pb^{2+}$ of PZT was substituted by 8${\sim}$12 atom% $Nd^{3+}$ ion, the structures were changed to cubic from tetragonal and its transmission had maximum value. Transmission increased as the stretching force constant $(k_s)$ of unit cell increased. It is supposed that the electro-optic characteristics might occur due to electron-transition from HOMO to LUMO of titanium ion.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.4
• /
• pp.1197-1205
• /
• 2018

UV protection cosmetics belong to functional cosmetics and contain organic or inorganic UV blocking pigments. The inorganic UV blocking pigments are mainly zinc oxide and titanium dioxide. It is known that inorganic UV blocking pigment has a diameter of 60 to 100 nm and has good blocking ability of UVA and UVB. Also, it has high inactivity against sunlight including UV and is excellent in safety. In addition, it is not absorbed or accumulated on the skin like organic pigments and does not cause skin irritation or allergy. In this study, mica, a plate-shaped inorganic pigment, nanosized titanium dioxide, an UV blocking material, and hydrophobic silica were surface-treated with surfactants. And then, titanium dioxide nanoparticles and silica were physically adsorbed on the mica by non-chemical mutual attraction due to differences in charge. Thereafter, the mica complex was surface-treated with silane to prepare a hydrophobic UV blocking pigment complex. The plate-shaped UV blocking composite improves the cohesiveness of a general nanoparticle material titanium dioxide, enhances UV blocking effect due to uniform dispersion, and can greatly improve dispersion stability in cosmetic formulations by surface treatment with hydrophobic property. The surface charge of the pigment was evaluated by zeta potential. The properties of the UV blocking pigment complex were evaluated by FE-SEM, XRD, FT-IR and UV-VIS.

• Journal of the Korean Vacuum Society
• /
• v.15 no.5
• /
• pp.527-533
• /
• 2006

Spinel $LiNi_xMn_{2-x}O_4$ thin films were synthesized up to x = 0.9 by a sol-gel method employing spin-coating. The Ni-substituted films were found to maintain cubic structure at low x but to exhibit tetragonal structure for $x{\geq}0.6$. Such cubic-tetragonal phase transition indicates that $Ni^{3+}(d7)$ ions with low-spin $(t_{2g}^6,e_g^1)$ state occupy the octahedral sites of the compound, thus being subject to the Jahn-Teller distortion. By x-ray photoelectron spectroscopy both $Ni^{2+}$ and $Ni^{3+}$ ions were detected. Optical properties of the $LiNi_xMn_{2-x}O_4$ films were investigated by spectroscopic ellipsometry (SE) in the visible?ultraviolet range. The measured dielectric function spectra by SE mainly consist of broad absorption structures attributed to charge-transfer (CT) transitions, $O^{2-}(2p){\rightarrow}Mn^{4+}(3d)$ for 1.9 $(t_{2g})$ and $2.8{\sim}3.0$ eV $(e_g)$ structures and $O^{2-}(2p){\rightarrow}Mn^{3+}(3d)$ for 2.3 $(t_{2g})$ and $3.4{\sim}3.6$ eV $(e_g)$ structures. Also, sharp absorption structures were observed at about 1.6, 1.7, and 1.9 eV, interpreted as due to d-d crystal-field transitions within the octahedral $Mn^{3+}$ ion. The strengths of these absorption structures are reduced by the Ni substitution. Rapid reduction of the CT transition strength involving the eg states for x = 0.6 is attributed to the reduced wavefunction overlap between the $e_g$ and the $O^{2-}(2p)$ states due to the tetragonal extension of the lattice constant by the Jahn-Teller effect.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.2
• /
• pp.180-184
• /
• 1999

The single crystals of $Mg_{0.15}Zn_{0.85}Te$ and $Mg_{0.15}Zn_{0.85}Te:Co^{2+}$(0.001%) were grown by vertical Bridgman method. Optical absorption properties of this compound were studied. As a result of the optical absorption spectra of $Mg_{0.15}Zn_{0.85}Te$, absorption peaks were related to exciton and the exciton level redshifts with increasing temperature, and temperature coefficient given to the value of $-5.8{\times}10^{-4}\;eV/K$ for the temperature range above 100 K. in the $Mg_{0.15}Zn_{0.85}Te:Co^{2+}$(0.001%) single crystal, the intracenter transitions due to $Co^{2+}$ ions were detected for $A-band:^4A_2(^4F) {\to}^4T_1(^4F),\; B-band:\; ^4A_2(^4F){\to}^4T_1(^4P)$, and the charge transfer transition near the absorption edge was observed in the wavelength range of 500 to 800 nm. According to the crystal field theory and Lucovsky formula, the crystal field parameter, Racah parameter and charge transfer energy were determined.

• Journal of the Korean Chemical Society
• /
• v.25 no.6
• /
• pp.351-360
• /
• 1981

Ultraviolet spectrophotometric investigations have been carried out on the system of durene with iodine, bromine, iodine monochloride and iodine monobromide in carbon tetrachloride. The results reveal the formation of the charge transfer complexes of the type, $C_6H_2(CH_3)_4{\cdot}X_2$ or $C_6H_2(CH_3)_4{\cdot}IX$(X denotes halogen atoms). The equilibrium constant were obtained in consideration of that absorption maxima due to the formation of the charge transfer complexes shift to blue with the increasing temperatures. The thermodynamic parameters, ${\Delta}H,\;{\Delta}G\;and\;{\Delta}S$ for the formation of the charge transfer complexes were calculated from these values. These results indicate that the relative stabilities of the durene complexes at each temperature decrease in the order, $ICl>IBr>I_2>Br_2$. This order may be a measure of their relative acidities toward durene, which is explained in terms of the relative polarizabilities of halogen molecules and the relative electronegativities of halogen atoms. These results combined with previous study of this series indicated that the relative stabilities of the polymethylbenzene complexes with iodine increase in the order; Benzene

• Journal of the Korean Chemical Society
• /
• v.25 no.2
• /
• pp.75-84
• /
• 1981

Ultraviolet spectrophotometric investigations have been carried out on the systems of mesitylene with iodine, bromine, iodine monochloride and iodine monobromide in carbon tetrachloride. The results reveal the formation of the charge transfer complexes of the type, $C_6H_3(CH_3)_3{\cdot}X_2$ or $C_6H_3(CH_3)_3{\cdot}IX$ (X denotes halogen atoms). The equilibrium constants were obtained in consideration of that absorption maxima due to the formation of the charge transfer complexes shift to blue with the increasing temperatures. Thermodynamic parameters, ${\Delta}H$, ${\Delta}G$ and ${\Delta}S$ for the formation of the charge transfer complexes were calculated from these values. These results indicate that the relative stabilities of the mesitylene complexes at each temperature decrease in the order, ICl > IBr > $I_2$ > $Br_2$. This order may be a measure of their relative acidities toward mesitylene, which is explaned in terms of the relative polarizabilities of halogen molecules and the relative electronegativities of halogen atoms. These results combined with previous study of this series indicated that the relative stabilities of the polymethylbenzene complexes with iodine increase in the order Benzene < Toluene < Xylene < Mesitylene Thus, analysis of these findings is discussed.