• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.930-935
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• 2004

$({Li}_{0.5}0{La}_{0.5}){TiO}_3$ (LLTO) solid electrolyte was grown on LiCo{O}_2 (LCO) cathode films deposited on $Pt/Ti{O}-2/Si{O}_2/Si$ substrate using pulsed laser deposition for all-solid-state lithium microbattery. LLTO solid electrolyte exhibits an amorphous phase at various deposition temperatures. LLTO films deposited at 10$0^{\circ}C$ showed a clear interrace without any chemical reaction with LCO, and showed an initial discharge capacity of 50 $\mu$Ah/cm$^2$-$\mu$m and capacity retention of 90 % after 100 cycles with Li anode in 1mol$ LiCl{O}_4$ in propylene carbonate (PC). The increase of capacity retention in LLTO/LCO structure than LCO itself was attributed to the structural stability of LCO cathode films by the stacked LLTO. The cells of LLTO/LCO with LLTO grown at $100^{\circ}C$ showed a good cyclic property of 63.6 % after 300 cycles. An amorphous LLTO solid electrolyte is possible for application to solid electrolyte for all-solid-state lithium microbattery.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.166.2-166
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• 2002

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.131-134
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• 2002

The effect of the addition on the densification, low temperature sintering, and microwave dielectric properties of the Ca[($Li_{1/3}Nb_{2/3}$)$_{1-x}$$Ti_{x}$]$O_{3-{\delta}}$/(CLNT) was investigated. $Bi_2O_3$ additives improved the dencification and reduced the sintering temperature from $1150^{\circ}C$ to $900^{\circ}C$ of CLNT microwave dielectric ceramics. As increasing $Bi_2O_3$ contents, the dielectric constants and bulk density were increased. The quality factor, however, was decreased slighty. The temperature coefficients of the resonant frequency shifted positive value as increasing $Bi_2O_3$ contents. The dielectric properties of Ca[($Li_{1/3}Nb_{2/3}$)$_{1-x}$$Ti_{x}$]$O_{3-{\delta}}$ and Ca[($Li_{1/3}Nb_{2/3}$)$_{0.8}Ti_{0.2}$]$O_{3-{\delta}}$ with 5wt% $Bi_2O_3$ sintered at $900^{\circ}C$ for 3h were $\varepsilon_{r}$=20, 35 Q.$f_{0}$=6500, 11,000 GHz, $\tau_{f}$=4, 13 ppm/$^{\circ}C$, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.275-285
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• 1996

The effect of heat-treatment on catalytic crystallization in $LI_2O-Al_2O_3-SiO_2$ glass system over its glass transition temperature was investigated. Glass composition $4Li_2O{cdot}22AL_2O_3{cdot}66SiO_2{cdot}2TiO_2{cdot}2.5ZrO_2{cdot}1.5P_2O_5{cdot}1.0Na_2O{cdot}1.0As_2O_3$ (wt%) was selected and heat-treated at different heating conditions to obtain transparent glass-ceramic. Nucleation and crystallization behaviour of this composition were estimated by differential thermal analysis (DTA) and X-ray diffractometer (XRD) and its thermal expansion coefficients were measured by Dilatometer. As a result, glass transition temperature was $730^{\circ}C$ and two maximum nucleation temperatures were estimated at $730^{\circ}C$ and 82$0^{\circ}C$ using JMA(Johson-Mehl-Avrami) equation by DTA. $ZrTiO_4$ $\beta$-Quartz solid solution and $\beta$-Spodumene crystals were identified by XRD. The optimum crystallization temperature was 92$0^{\circ}C$ and three step heating schedule was expected to be useful to obtain transparent glass-ceramic.

• Journal of the Korean Electrochemical Society
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• v.12 no.3
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• pp.239-244
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• 2009

This paper aims to report the effect of surface treatment on graphite and its effect on the improvement of $Al_2O_3$ and $nano-Li_4Ti_5O_{12}$. The structure and property of surface treatment on graphite were determined by scanning electron microscopy, transmission electron microscopy and electrochemical property and safety were determined by charge/discharge cycler, accelerating rate calorimeter. The composite with different metallic oxide exhibited the first efficiency of 82.5% and specific capacity of 350 mAh/g. Although the composite showed same efficiency and specific capacity at first cycle, surface treatment on graphite by $nano-Li_4Ti_5O_{12}$ exhibited a higher charge/discharge rate, cycle life and thermal stability.

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.205-210
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• 2011

Structural and electrochemical properties of spinel oxide $LiMn_2O_4$ thin films prepared by using a sol-gel method on Pt/Ti/$SiO_2$/Si substrates were investigated. When Li/Mn molar ratio of the film was smaller than 0.5, $Mn_2O_3$hase was found to coexist with $LiMn_2O_4$. Half-cell batteries fabricated using the $LiMn_2O_4$ films as the cathode were put into chargedischarge (C-D) cycles and the change in structural properties of the cathode after the cycles was examined by X-ray diffraction and Raman spectroscopy. As the C-D cycle number increases, the discharge capacity of pure $LiMn_2O_4$ battery gradually decreases, being reduced to 72% of the initial capacity at 300 cycles. Such capacity fading is attributable to the decrease in the number of $Li^+$ ions that return to the tetrahedral sites of the spinel structure during the discharge step and the resultant increase in $Mn^{4+}$ density in the film. Also, $Mn_2O_3$ phase gradually appeared in the film as the cycle number increases.

• Journal of the Korean institute of surface engineering
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• v.31 no.6
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• pp.359-370
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• 1998

TiAl-based intermetallic compounds were electro-bornizel in the mixture of $Na_2B_4O_7$, KCL and LiCl in the termetature rage between 850 and $1000^{\circ}C$for various times (1-5 hours)under the fixed current density of 0.5 A/$cm^2$. The optimized composition of electrolyte in this work was decided to be 76.9 wt% $Na_2B_4O_7$-19.2 wt.%(0.7KCl-0.3LiCl) -3.9 wt.% al. The samples with boronized layer were investigated by SEM, XRD and EDS. The surface micro-hardness of boronized TiAl was also evaluated using Micro Vickers Hardness Tester. The sample, boronized at $900^{\circ}C$ for 4 hours in the above composition of electrolyte under the current density of 0.5 A/$\textrm{cm}^2$, has about 36$\mu\textrm{m}$ think layer on the surface, and its surface micro-hardness was measured to be 1263 Hv. From the results of SEM, XRD and EDS, the layer consisted of $TiB_2$ sublayer and Al-oxide sub layer. Al-depleted layer below the Al-oxide sudlayer was also detected. The activation energy for formation of boronized layer in this study was calculated as 178 Kcal/moleK.

• Journal of Sensor Science and Technology
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• v.11 no.4
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• pp.247-253
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• 2002

For fabrication of the pyroelectric IR sensor $(Pb,La)TiO_3(PLT)$/$LiTaO_3$/(LTO)/PLT ferroelectric thin films was deposited by rf magnetron sputtering followed by rapid thermal annealing and the crystallinity as a function of annealing temperature and time was investigated. Permittivity and dielectric loss factor of ferroelectric thin films as a function of c-axis preffered orientation was measured. Also pyroelectric coefficient of ferroelectric thin films with largest c-axis preffered orientation was measured and obtain figure of merit of voltage response($F_V$) and detectivity($F_D$). In this case $F_V$, $F_D$ was $5.63{\times}10^{-10}\;C{\cdot}cm/J$, $1.98{\times}10^{-8}\;C{\cdot}cm/J$, respectively.

• Journal of the Korean Chemical Society
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• v.27 no.4
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• pp.273-278
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• 1983

With the synthetic standards, valuable metals $(Ta_2O_5, Nb_2O_5, TiO_2, SnO_2$, and $ZrO_2$) in the tin slags have been determined by the x-ray fluorescence spectrometry. The powder sample and the standards are homogeneously mixed with anhydrous $Li_2B_4O_7$ and La_2O_3$ in weight ratio of 15 : 42 : 3 respectively. The mixed material is fused at $1,150^{\circ}C$ for 30 minutes to be changed into the glass bead. The bead is ground to (-) 325 mesh size and pelletized. The analytical results obtained in this work are consistent with the data obtained by other common methods within allowable error range. The standard deviation for $Ta_2O_5$ in PTS-H sample is 0.12 % at level of 3.40 % content.

• Journal of the Korean Ceramic Society
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• v.13 no.1
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• pp.30-34
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• 1976

In general the chemical composition of glass ceramics in Li2O-Al2O3-SiO2 system is similar to the composition of $\beta$-spodumene (Li2O-Al2O3-4SiO2). With the object to manufacture the glass ceramics which can be produced in the domestic pot the composition of glass was so settled at 1.0 Li2O.0.9Al2O3.6.0SiO2 in order to reduce the contents of Li2O, to prevent the corrosion of the pot and to decrease the cost of raw materials. 0.2 mole and 0.1 mole of the mixture of TiO2 and ZrO2 as nucleants were added to the basic composition of 1.0 Li2O-0.9Al2O3-6.0SiO2. Each sample was divided into two kinds with a TiO2/ZrO2 ratio of 2 to 1 and the other with a TiO2/ZrO2 ratio fo 1 to 1. Thermal expansion coefficient, the most important property of glass ceramics, was tested. The softening point and the melting point of the samples were observed by the use of a heating microscope. The results obtained were as follows. The manufacturing of glass ceramics seems to be possible in the industrial plant using the domestic pot. 1) The composition of the glass which can be melted in the domestic pot process was near 1.0 Li2O.0.9Al2O3.6.0SiO2. 2) The temperature range of crystal creation and crystal growth was between 850-94$0^{\circ}C$, and 5 hours holding the samples at the temperature range was enough to crystallize them. The major crystal was $\beta$-spdumene and there existed petalite partialy. 3) The thermal expansion coefficient fo the crystallized glass was negative. 4) The deforming point of the crystallized glass was 1435$^{\circ}C$.