• Korean Journal of Crystallography
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• v.9 no.2
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• pp.138-142
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• 1998

Lithium triborate, LiB3O5(Mr=119.37), 단결정을 상단 종자정 융액법으로 성장시켰으며, 결정구조를 X-선 회절법으로 연구하였다. 결정계는 사방정계이며 공간군은 Pna21(No. 33)이다. 단위포의 상수는 a=8.432(1) , b=7.364(1) , c=5.110(1) , α=β=γ=90.00o, V=317.3(6) 3, V=4, Dx=2.50 gcm-3, MoKα1, λ=0.71069 , μ=2.3/cm, F(000)=232, T=293 K 이었다. 최종 구조의 오차인자는 520개 회절 점에서 각각 R=0.0222과 wR=0.0582이었다.

• Polymer(Korea)
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• v.33 no.6
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• pp.544-550
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• 2009

In this study, we have designed [Epoxy/PEG] polymer gel electrolyte systems by thermal curing the mixtures of epoxy, PEG, imidazole catalyst, and a plasticizer of 1:1 ethylene carbonate and propylene carbonate in the presence of $LiPF_6$ salt. In order to enhance the poor mechanical property of the Corresponding [Epoxy/PEG] gel electrolyte PVdF-HFP was incorporated into the system. The ionic conductivities of the polymer gel electrolytes were related to the amount of PVdF-HFP in blends as well as the amount of liquid electrolyte. The optimized gel system showed room-temperature conductivities of $2.56\times10^{-3}S/cm$.

• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.115-120
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• 2000

All solid-state thin film micro-batteries consisting of lithium metal anode, an amorphous LiPON electrolyte and cathode of vanadium oxide have been fabricated and characterized, which were fabricated with cell structure of $Li/LiPON/V_2O_5Pt$. The effect of various oxygen partial pressure on the electrochemical properties of vanadium oxide thin films formed by d.c. reactive sputtering deposition were investigated. The vanadium oxide thin film with deposition condition of $20\%\;O_2/Ar$ ratio showed good cycling behavior. In in-siか process, the LiPON electrolyte was deposited on the $V_2O_5$ films without breaking vacuum by r.f. magnetron sputtering at room temperature. After deposition of the amorphous LiPON, the Li metal films were grown by a thermal evaporator in a dry room. The charge-discharge cycle measurements as a function of current density and voltage variation revealed that the $Li/LiPON/V_2O_5$ thin film had excellent rechargeable properly when current density was $7{\mu}A/cm^2$. and cut-off voltage was between 3.6 and 2.7V In practical experiment, a stopwatch ran on this $Li/LiPON/V_2O_5$ thin film micro-battery. This result means that thin film micro-battery fabricated by in-siか process is a promising for power source for electronic devices.

• Polymer(Korea)
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• v.24 no.2
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• pp.259-267
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• 2000

Gel polymer electrolytes were prepared from poly(vinylidene fluoride-co-hexafluoro propylene)[P(VdF-co-HFP)] that had higher mechanical properties as well as higher dielectric constant ($\varepsilon$=8~13) than other polymeric matrix. Mechanical properties and ionic conductivities have been investigated as a function of blend ratio of electrolyte solution and polymer matrix. Ethylene carbonate (EC)/${\gamma}$-butyrolactone (${\gamma}$-BL) and lithium triflate (LiCF$_3$SO$_3$) were used as solvent and salt, respectively. The mechanical properties such as tensile strength, tensile modulus, compression modulus, and dynamic shear modulus were evaluated. The highest ionic conductivity was 1.09$\times$10$^{-3}$ S/cm for PVH40 containing 28.6 wt% of P(VdF-co-HFP) at $25^{\circ}C$. Tensile strength, tensile modulus and compression modulus were increased with P(VdF-co-HFP) content and abruptly changed between PVH70 and PVH80. Dynamic shear moduli showed a typical gel behavior and changed with shear strain.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.196-199
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• 2000

마이크로파용 세라믹 유전체로 사용되는 MgTiO$_3$-CaTiO$_3$계 유전체에 Li을 첨가하여 이때 얻어지는 마이크로파 유전특성과 소결특성에 대하여 알아보았다. 94MgTiO$_3$-6CaTiO$_3$으로 주조성을 고정시키고 여기에 Li$_2$CO$_3$를 Li원자 기준으로 0 ~ 10 mol% 범위 안에서 첨가하여 1200~140$0^{\circ}C$의 온도에서 4시간 소결하였다. Li의 첨가량이 적을 때에는 유전체의 품질계수와 유전상수가 모두 감소하였으나 약 lmol% 이상 되면 다시 증가하였으며, 이후 첨가량이 과도해지면 다시 서서히 감소하는 경향을 볼 수 있었다. 1.0 ~ 3.0 mol%의 첨가량 범위 안에서 Li은 MgTiO$_3$-CaTiO$_3$계 유전체의 품질계수를 증가시켜주는 역할을 하는 것으로 나타났다 1.5mol%의 Li을 첨가하고 1275$^{\circ}C$에서 4시간 소결한 시편에서 유전상수는($\varepsilon$$_{r}$) 20.0, Qf는 78,000 그리고 공진주파수 온도계수($\tau$$_{f}$)는 -1.6ppm/$^{\circ}C$의 결과를 얻을 수 있었다.다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.3
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• pp.190-196
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• 2001

The microwave dielectric properties and a sintering behavior of MgTiO$_3$-CaTiO$_3$ ceramics doped with Li were investigated. The main composition was fixed as 0.94MMgTiO$_3$-0.06CaTiO$_3$ and Li$_2$CO$_3$was added excessively in the range of 0~10 mol% (with reference to Li atoms) and the specimens were sintered at 1200~140$0^{\circ}C$ for 4 hours. When the amount of Li was small the quality factor and dielectric constant were reduced, while those tow properties increased if the Li amount was above 1 mol%. But if Li was overly added those dielectric properties decreased again. Li, if added in the composition range of 1.0~3.0 mol%, can increase the quality factor of MgTiO$_3$-CaTiO$_3$ ceramics. The optimum amount of Li was 1.5mol% and sinterign condition was 1275$^{\circ}C$/4hr, at which we cudl obtain following results ; dielectric constant ($\varepsilon$$_{r}$) of f20.0, quality factor(Qxf$_{0}$) of 78,000 GHz and temperature coefficient of resonant frequency($\tau$$_{f}$) of -1.6 ppm/$^{\circ}C$.>.>.>.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.545-549
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• 2001

We have produced electrolyte solution out of 1.15M LiPF$\sub$6/ EC/EMC/DEC/PC(30/55/10/5 by vol%) as a reference, and at the same time, performed basic physical property test using a single solvent of 1.15M LiPF$\sub$6/DEC, DMC, EMC and a 2 component electrolyte solution of 1.15M LiPF$\sub$6/ EC/DEC(1/2 by vo%%) and PC/DEC(1/2 by vol%). Cyclic Voltammetry Analysis showed that, compared to existing carbonate organic solvent, the addition of DEC, DMC and EMC brought the de-decomposition peak of salt anion of PF$\sub$6/$\^$-/ and the solvent at lower oxidization potential of 2.3V, 0.7V and 2.1V(vs. Li/Li$\^$+/\`). In addition, a kinetics current peak, in which intercalation of Li$\^$+/ is proceeded at 750mv, 450mv(vs. Li/Li$\^$+/), was confirmed. These findings suggest that the DEC solvent decomposition occurred at an electric potential lower than that of oxidization of existing carbonate organic solvent. Through the impedance analysis, we checked electric charge transfer resistance(R$\sub$ct/) according to the electric potential of Li$\^$+/ intercalation at 750mv(vs. Li/Li$\^$+/), which was the same as the resistance (R$\sub$f/) and cyclic voltammetry of SEI film that was formed at Reference. By doing so, we found that the significant decrease of polarization resistance(R$\sub$p/) when Reference was played a part in the formation of compact SEI layer at the initial decomposition reaction.

• Journal of the Korean Ceramic Society
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• v.39 no.1
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• pp.26-32
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• 2002

The effects of $Nd_2O_3$ addition to $Q{\cdot}f_{0}(GHz)$ ceramics with ${\varepsilon}_r$ of 126, $Q{\cdot}f_{0}(GHz)$ of 2240 and of $68\;ppm/^{\circ}C$ on their microwave properties were investigated. For the addition of 5 wt% $Nd_2O_3$, the dielectric constant (${\varepsilon}_r$) showed maximum value of 131, then decreased with the further addition of $Nd_2O_3$. $Q{\cdot}f_{0}(GHz)$ value was still increased to 3533 with 9 wt% $Nd_2O_3$ addition, it is influenced by densification of grain boundary. With more addition of $Nd_2O_3$ up to 18 wt%, the abnormal grain growth have influence on the decreasing of $Q{\cdot}f_{0}(GHz)$ value. But with the further addition of $Nd_2O_3$ over 25 wt%, the $Q{\cdot}f_{0}(GHz)$ value was again increased by the effect of the second phase ($Nd_2Ti_2O_7$) forming. The temperature coefficient of resonant frequency (${\tau}_f$) was decreased from $+\;68\;ppm/^{\circ}C$ with the addition of $Nd_2O_3$, reached $0\;ppm/^{\circ}C$ at 12 wt% addition, and became negative with the further addition of $Nd_2O_3$. The optimum microwave dielectric properties were obtained for $0.3CaTiO_3-0.7(Li_{1/2}Nd_{1/2})TiO_3$ with 9 wt% $Nd_2O_3$ sintered at $1425^{\circ}C$ for 3 hrs. The dielectric constant (${\varepsilon}_r$), the $Q{\cdot}f_{0}(GHz)$ value, and the temperature coefficient of resonant frequency (${\tau}_f$) were 108, 3533, and $+\;6\;ppm/^{\circ}C$, respectively.

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.181-185
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• 2005

Lithium cobalt oxide thin film cathode, having thickness of $2.9{\mu}m$ with area of $4cm^2$, was deposited on platinum patterned alumina substrate by radio frequency magnetron sputtering. Li/Co molar ratio, which is an important factor for battery performance, was measured as a function of argon working pressure and applied R.F. power. Constant current charge and discharge performances were characterized with high rate discharge and cycling behavior. Using AC impedance analysis, internal resistance of the thin film battery was measured and simulated by proposed equivalent circuit model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.331-334
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• 2000

The organic electroluminescent(EL) device has gathered much interest because of its large potential in materials and simple device fabrication. We fabricated EL devices which have a blended single emitting layer containg poly(Nvinylcarbazole)[PVK] and poly(3-dodecylthiophene)[P3DoDT]. The molar ratio between P3DoDT and PVK changed with 1:0, 2:1 and 1:1. To improve the external quantum efficiency of EL devices, we applied insulating layer, LiF layer between polymer emitting layer and AI electrode. All of the devices emit orange-red light and it's can be explained that the energy transfer occurs from PVK to P3DoDT. Within the molar ratio 1:0, 2:1 and 1:1, the energy transfer was not saturated, which results in the not appearance of PVK emission in the blue region. In the voltage-current and voltage-light power characteristics of devices applied LiF layer, current and light power drastically increased with increasing with applied voltage. In the consequence of the result, the light power of the device have a molar ratio 1:1 with LiF layer was about 10 times larger than that of the device without PVK at 6V.