• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.214-216
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• 2006

In this study, in order to develop the composition ceramics for low loss and low temperature sintering multilayer piezoelectric actuator, PMN-PZN-PZT ceramics were fabricated using two stage calcination method and $Li_2CO_3$, $Bi_2O_3$ and CuO as sintering aids and their piezoelectric characteristics were investigated according to the 2nd calcination and sintering temperature. At the calcination temperature of $750^{\circ}C$ and sintering temperature of $930^{\circ}C$, density, electromechanical coupling factor ($k_p$), mechanical quality factor ($Q_m$), Dielectric constant (${\varepsilon}_r$) and piezoelectric constant ($d_{33}$) of specimen showed the optimum value of $7.94g/cm^2$ 0.581, 1554, 1555 and 356pC/N, respectively for multilayer piezoelectric actuator application.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.4
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• pp.128-135
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• 2022

The inside of a quartz glass crucible for semiconductor processing, called a transparent layer, is manufactured using synthetic silica powder. Bubbles existing in the transparent layer of the crucible cause a problem of reducing the quality of the crucible as well as the yield of the silicon ingot. Therefore, the main goal of the synthetic silica powder, which is the raw material of the transparent layer, is to minimize the bubble generation factor. For this purpose, in the case of synthetic silica powder, it is necessary to minimize silanol groups, carbon and pores. In this study, synthetic silica gel was prepared using the sol-gel method, and changes in carbon content and specific surface area were investigated according to calcination temperature and dwelled time in a two-stage calcination process. The first-stage calcination process was performed between 500℃ and 600℃ and the second-stage calcination process was performed between 1000℃ and 1100℃. The dwelled time was carried out from 10 minutes to a maximum of 12 hours. The carbon content of the powder calcined at 1000℃ for 1 hour was 0.0031 wt.%, and the specific surface area of the powder calcined at 1100℃ for 12 hours was 16.6 m²/g.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.89.2-89
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• 2002

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.524-529
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• 2008

In this paper, in order to develop low loss multilayer actuator, piezoelectric properties of PZW-PMN-PZT multilayer actuator sintered at $900^{\circ}C$ low temperature were investigated according to the number of multilayer. The multilayer actuator was fabricated using tape casting method and used pure Ag internal electrode. The density above $8.0\;g/cm^3$ was obtained at all specimens. With increasing number of multilayer, effective electromechanical coupling factor($k_{eff}$) was increased. $k_{eff}$ of multilayer actuator shows the maximum value of 0.283 at 11 layers actuator. However, effective mechanical quality factor(Qm') was decreased according to the increase of number of multilayer. The Qm' of multilayer actuator showed the maximum value of 920 at 5 layers actuator.

• Electrical & Electronic Materials
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• v.6 no.5
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• pp.436-445
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• 1993

2단계하소법에 의해 낮은 하소온도에서 미세하고도 균일한 PZT분말을 합성하였다. 우선 Zr $O_{2}$와 Ti $O_{2}$ 혼합분말을 1차하소하여 (Z $r_{0.53}$ $Ti_{0.47}$) $O_{3}$(ZTO) 분말을 합성하고 이 ZTO 고용분말에 PbO와 N $b_{2}$ $O_{5}$을 혼합한 후 650-800.deg.C에서 2시간 하소하여 PZT 분말을 합성하였는데 얻어진 분말은 고상반응법에 비해 미세할 뿐만 아니라 XRD 분석결과 710.deg.C의 낮은 하소온도에서도 PZT 단일상을 나타내었다. 2단계하소법에 의해 하소온도를 낮출 수 있는 주된 이유로는 고상반응법에서는 중간생성물인 PbTi $O_{3}$상의 생성이 수반됨으로 850.deg.C 이상 되어야만 안전한 PZT가 생성될 수 있는 점을 들 수 있다. 또 2단계하소법에 의하면 950.deg.C이하의 낮은 소결온도에서도 치밀화가 미루어지는 소결이 가능함을 알 수 있었는데 이와같이 소결온도를 낮출 수 있는 것은 고상반응법에 비해 미세한 PZT 분말을 사용하였기 때문이라 풀이된다.이된다.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.928-935
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• 2010

A bag filter system was partially burnt down during a trial run of waste wood incineration boiler. This brought about unburned hydrocarbon which caused a rapid deactivation of low temperature SCR catalyst set up in two stage after the bag filter. The deactivated catalyst was investigated in order to trace the origin by several characterization methods such as XRD, EDX, BET, TGA, SEM. The deactivated catalyst was regenerated by different methods such as acid washing, water washing in ultrasonication, and calcination treatment under air condition. It is found the calcination treatment under air condition at $450^{\circ}C$ for 2 hours to be the best regeneration method. The catalytic activity was measured in the form of 2 cm ${\times}$ 2 cm ${\times}$ 10 cm (catalyst weight 10 g) honeycomb type. A deNOx efficiency of the regenerated catalyst showed 100% at $180^{\circ}C$ which is the same level of fresh one.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.798-803
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• 2003

In synthesis of nano powders, the hard agglomeration for the synthesized powders occurred during the drying processing. In order to avoid hard agglomeration in particles the freeze drying process was used in this experiment. e fabricated the Yttira-Doped Ceria(YDC) nano powder by co-precipitation. Starting materials used in experiments were the cerium(III) nitrate and yttrium(III) nitrate solution with 야-water, which two solutions were mixed and then the precipitated hydroxides were prepared for adding sodium hydroxide. The co-precipitated powders were dried by the thermal drying at 8$0^{\circ}C$ for 24 h and by freeze drying at -4$0^{\circ}C$, 30 mtorr for 72 h. The lattice parameter and crystallite size as a function of calcination temperature was characterized by XRD analysis. The lattice parameter of YDC was decreased with addition amount of yttrium and was estimated as 5.401683 $\AA$ at $700^{\circ}C$. Crystallite size were calculated by XRD-LB method, and morphologies were confirmed with the observation of TEM and SEM. The freeze dried YDC powders had medium diameter of 17 nm with more uniform size distribution than the thermal dried YDC posers, which were mainly ascribed to the difference of agglomerates formation during drying stage.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.436-438
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• 2009

In this study, in order to develop the composition of ceramics capable of being sintered at low temperature with high piezoelectric properties, PZW-PMN-PZT system ceramics for piezoelectric energy harvesting application were manufactured according to the amount of PZW addition. And also, their microstructural, dielectric and piezoelectric properties were investigated. At the sintering temperature of $930^{\circ}C$, a 5 mol% PZW substituted specimen showed a maximum value of density = $7.905g/cm^3$, kp = 0.585, $d_{33}$ = 351pC/N and Qm =1,254, respectively.