• 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

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.374-377
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• 2009

The characteristics of the deposited thin films of the zinc oxide (ZnO) at different oxygen pressures will be elucidated in this work. The resistivity of ZnO thin films were dominated by the carrier concentration under high oxygen pressure conditions while controlled by the carrier mobility at low oxygen ambiences. In addition, we will show the characteristics of the transparent ZnO based thin film transistor (TFT) fabricated at a full room temperature process with gate dielectric of gadolinium oxide ($Gd_2O_3$) thin films.

• Journal of the Korean Ceramic Society
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• v.22 no.2
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• pp.3-10
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• 1985

In the study the characteristics change of crystallized $Li_2O$.$Al_2O_3$.$SiO_2$ glass-ceramics when varying RO ratio and increasing Al2O3 were investigated to produce a glass-ceramics with high mechanical strength and low thermal expansion. Parent glass was obtained by melting at 1,350~1,40$0^{\circ}C$ for 3 hours and annealing at 45$0^{\circ}C$ and the various physical characteristics were measured. Results were as follows; 1. When ZnO was replaced by MgO thermal expansion coefficient was lowered when increasing ZnO content. 2. Major crystal phase was $\beta$-spodumene the crystal growth mophology was the three dimensional sphere and the activation energy for crystallization was 54.6 Kcal/mol. 3. Parent glass heat-treated at 95$0^{\circ}C$ for 10 hours had ; a) thermal expansion coeff. of $23.2{\times}10^{-7}$/$^{\circ}C$ b)whiteness of 76 c) microhardness of 1,089kg/$mm^2$

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.971-972
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• 2006

Mechanochemical synthesis of zinc ferrite, $ZnFe_2O_4$, was attempted from a powder mixture of iron (III) oxide, alpha-$Fe_2O_3$ and zinc (II) oxide, ZnO. Nanocrystalline zinc ferrite, $ZnFe_2O_4$ powders were successfully synthesized only bymilling for 30 hours. Evidence of the $ZnFe_2O_4$ formation was absent for the powders milled for 10 and 20 hours; the milling lowered the crystallinity of the starting materials. Heating after milling enhanced the formation of $ZnFe_2O_4$, crystal growth of $ZnFe_2O_4$ and the unreacted starting materials. The unreacted starting materials decreased their amounts by heating at higher temperatures.

• Korean Journal of Materials Research
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• v.18 no.11
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• pp.617-622
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• 2008

In this study, the additivity factors of compositions to density and glass transition point ($T_g$) in a $xLi_2O-(1-x)[(1-y)TeO_2-yZnO]$ (0$T_g$ was discussed. As a method for predicting the relation between glass structure and ionic conductivity, density was measured by the Archimedes method. The glass transition point was analyzed to predict the relation between ionic conductivity and the bonding energy between alkali ions and non-bridge oxygen (NBO). The relation equations showing the additivity factor of each composition to the two properties are as follows: Density(g/$cm^3$) = $2.441x_1\;＋\;5.559x_2\;＋\;4.863x_3\;T_g(^{\circ}C)$ = $319x_1\;＋\;247x_2\;＋\;609x_3\;－\;1950x_1x_3$ ($x_1$ : fraction of $Li_2O$, $x_2$ : fraction of $TeO_2$, $x_3$ : fraction of ZnO) The density decreased as $Li_2O$ content increased. This was attributed to change of the $TeO_2$ structure. From this structural result, the electric conductivity of the glass samples was predicted following the ionic conduction mechanism. Finally, it is expected that electric conductivity will increase as the activation energy for ion movement decreases.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.2 no.2
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• pp.20-32
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• 1992

$Na_2O-CaO-MgO-Al_2O_3-SiO_2$ glass was taken as a basic glass and then $Li_2O$ O.5wt%, $K_2O$ 2.0wt% were substituted to $Na_2O$content, MgO 12.0wt %, ZnO 6.0wt % to CaO content. And also nucleation agent $ZrO_2 and $CaF_2$ were added to 1-2wt% respectively. The crystal according to the compositions appeared wollastonite, diopside and diopside.tremolite. The glasses substituted NazO by LizO was decreased thermal expansion coeffcient but substituted by ZnO was opposite direction and both of them increased bending strength. In the ratio of ZrOz to CaF, each 1: 1 and 1: 2 have shown considerable crystal growth at $1000^{circ}C~1050^{\circ}C$ and high bending strength, but the glass in the ratio 1: 2 have shown lowest thermal expansion coefficient. The activation energy was at the glass in the ratio of ZrO, to CaFz 1:2 evaluated 55.24kvsl/mol by Ozawa type and 53.05kal/mol by kissinger type.

• Journal of the Korean Ceramic Society
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• v.41 no.2
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• pp.165-169
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• 2004

Microwave dielectric properties and the behavior of low-temperature sintering of $Zn_{1-x}(Li_{1/2}La_{1/2})_xTiO_3$ ($0.01{\leq}x{\leq}0.05$) with 4 wt% $H_3BO_3$ were investigated as a function of $(Li_{1/2}La_{1/2})^{2+}$ content. The sintering temperature of the specimens can be reduced from $1150^{\circ}C$ to $875^{\circ}C$ with the addition of 4 wt% $H_3BO_3$ as a sintering agent. Dielectric constant (K) and Temperature Coefficient of resonant Frequency (TCF) with the substitution of ($(Li_{1/2}La_{1/2})^{2+}$ ion depended on dielectric mixing rule. Quality factor (Qf) depended on density and microstructure. Typically, K of 26.5, Qf of 19,030 GHz and TCF of 7.5 ppm$/^{\circ}C$ were obtained for the specimens with x=0.03 sintered at $875^{\circ}C$ for 3 h.

• Analytical Science and Technology
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• v.10 no.6
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• pp.439-444
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• 1997

Twelve kinds (1set) standard materials of chemical ingredients of lead zirconate titanate[$Pb(ZrTi)O_3$] have been developed in order to determine fast and accurate measurement of X-ray fluorescence spectrometry. Especially, we used diluted(ahout sixteen times) filling compound($Li_2B_4O_7/LiBO_2=4/1$) to consider removal effect of matrix, storage convenience, and homogenous characteristics. As a result from the four different laboratories, we obtained extremly good agreement about the standard curve on twelve standard materials which containing eleven elements, PbO, $ZrO_2$, $TiO_2$, SrO, $WO_3$, $La_2O_3$, $Cr_2O_3$, MgO, $Nb_2O_5$, and $MnO_2$. The correlation factor of standard curve was over 0.998. However, ZnO has relatively low correlation factor, 0.977, because the concentration was 10ppm lower than other original materials. This analysis reveals that ZnO has shown the poor linearity as well as low fluorescence intensity. In present work, XRF standard materials are useful for determining a rapid and accurate results for major and minor elements concentration among PZT.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.218-219
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• 2005

In this paper, in order to develop Pb-free piezoelectric ceramics, $[Li_{0.04}(Na_{0.44}K_{0.52})-(Nb_{0.86}Ta_{0.10}Sb_{0.04})]O_3$ ceramic was fabricated with the variation of ZnO addition. Piezoelectric properties of the ceramic were varied with the amount of ZnO addition and showed the maximum kp value at 0.2 wt% ZnO addition. Qm of ZnO added ceramics showed lower values than the non-added ceramics, however, the kp was increased by the addition of ZnO up to 0.2 wt%. At the sintering temperature of 1110$^{\circ}C$ and the calcination temperature of 850$^{\circ}C$, the optimal values of density=473g/$cm^3$, kp=0.473, $\varepsilon_r$=1403 were obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.707-711
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• 2006

ZnO was doped up to 0.3 wt% for improving the electrical properties of lead-free $[Li_{0.04}(Na_{0.44}Ko_{0.52})-(Nb_{0.86}\;Ta_{0.10}\;Sb_{0.04})]O_3$ piezoelectric ceramics. The ceramics were fabricated with the conventional sintering processes. Crystal structure of the samples was tetragonal phase regardless of ZnO amount. However, the piezoelectric properties were varied with the ZnO amount. The electro-mechanical coupling factor $(k_p)$ was with the ZnO amount up to 0.2 wt% but decreased with the further addition. the maximum value of $k_p$ was 0.475. Density, piezoelectric charge constant and relative dielectric constant was also showed maximum value at 0.2 wt%. The maximum values are $4.75g/cm^3$, 275 pC/N, 1403, respectively. In contrast, the mechanical quality factor $(Q_m)$ was not varied with increasing the ZnO addition up to 0.2 wt% but rapidly increased at 0.3 wt%.