투광성 전기 광학용 소자의 제조에 관한 연구

김재육,이태근,임응극 한국세라믹학회 1985 한국세라믹학회지 Vol.22 No.6

In order to fabricate the translucent electrooptic ceramics which are comparable to PLZT, $PNZT^*$ has been prepared from aqueous solutions of their itrate and chlorides. In the quarternary $Pb^{1-x} Nd_x(Zr_{0.63} Ti_{0.37})^{1-\frac{x}{4}O_3$, (PNZT) $(0.02\le x\ge 0.12)$ system cold-pressed PNZT slugs were sintered in $O_2$ in pt-crucible for 45 min. at 118$0^{\circ}C$ and were then heat-treated in air for 60 hrs. at 120$0^{\circ}C$ in Al2O3 crucibles containing $PbZrO_3$ powder to control the atmosphere. Mean particle size of calcined PNZT powders was 0.1~0.15${\mu}{\textrm}{m}$. It was found that the maximum value of optical transmission has been revealed at 6~8 at. % $Nd_2O_3$ added body and that their dielectric constant has been decreased as the frequency increased. Curic temperature has been varied inversely with $Nd^{3+}$ ion content up to 8 at. % and become constant above this value. $^*Pb_{1-x}Nd_x(Zr_{0.63} Ti_{0.37})_{1-2/4}O_3$

고체산화물연료전지 개발 현황

김재육,황일두,이준,김진영 한국세라믹학회 2012 세라미스트 Vol.15 No.3

CaCrO₄ 첨가에 따른 LCCC(La_0.8Ca_0.2Cr_0.9Co_0.1O_3-_δ)의 전이액상소결거동

이호창,강보경,이준형,허영우,김재육,김정주,Lee, Ho-Chang,Kang, Bo-Kyung,Lee, Joon-Hyung,Heo, Young-Woo,Kim, Jae-Yuk,Kim, Jeong-Joo 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.2

In this study, in order to improve densification of $La_{0.8}Ca_{0.2}Cr_{0.9}Co_{0.1}O_{3-\delta}$ (LCCC), which is known for one of the most proper candidate interconnector materials in the solid oxide fuel cells, $CaCrO_4$ was prepared via solid oxide synthesis route and added to the LCCC with different amount and particle sizes. As the amount of the $CaCrO_4$ increased, porosity of the sintered samples increased, and the pore size was proportional to the particle size of the $CaCrO_4$. This supports the fact that the $CaCrO_4$ phase forms liquid during sintering and permeate into the matrix leaving behind large pores. Then the liquid reacts with the matrix through the solid solution. However, when the samples were sintered with a slow ramp up rates, the porosity decreased. This is thought to be caused by the progressive solid solution of $CaCrO_4$ before the temperature reach to the melting temperature and forms a fluent amount of liquids. The sintering behavior of the LCCC with the addition of $CaCrO_4$ was analyzed through the transient liquid phase sintering on the basis of the microstructure observation and phase identification by x-ray diffraction.

CaCrO4 첨가에 따른 LCCC(La0.8Ca0.2Cr0.9Co0.1O3-δ)의 전이액상소결거동

이호창,강보경,이준형,허영우,김재육,김정주 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.2

In this study, in order to improve densification of La0.8Ca0.2Cr0.9Co0.1O3-δ (LCCC), which is known for one of the most proper candidate interconnector materials in the solid oxide fuel cells, CaCrO4 was prepared via solid oxide synthesis route and added to the LCCC with different amount and particle sizes. As the amount of the CaCrO4 increased, porosity of the sintered samples increased, and the pore size was proportional to the particle size of the CaCrO4. This supports the fact that the CaCrO4 phase forms liquid during sintering and permeate into the matrix leaving behind large pores. Then the liquid reacts with the matrix through the solid solution. However, when the samples were sintered with a slow ramp up rates, the porosity decreased. This is thought to be caused by the progressive solid solution of CaCrO4 before the temperature reach to the melting temperature and forms a fluent amount of liquids. The sintering behavior of the LCCC with the addition of CaCrO4 was analyzed through the transient liquid phase sintering on the basis of the microstructure observation and phase identification by x-ray diffraction.

SOFC 연결재용 Al이 도핑된 (La_0.8Ca_0.2)(Cr_0.9Co_0.1)O₃(LCCC)계 세라믹스의 합성 및 치밀화 특성

이호영,강보경,이호창,허영우,김정주,김재육,이준형,Lee, Ho-Young,Kang, Bo-Kyung,Lee, Ho-Chang,Heo, Young-Woo,Kim, Jeong-Joo,Kim, Jae-Yuk,Lee, Joon-Hyung 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.5

In the $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1})O_3$ (LCCC), which has been using as interconnector materials in SOFC, Al ions were substituted for Co because ionic radius of Al is similar to that of Co. Because of the almost identical ionic radius of Al and Co, the substitution was not thought to be affect the tolerance factor of LCCC, and the densification behavior, high temperature electrical conductivity and thermal expansion coefficient were examined as a function of Al concentration. In the cases of the x= 0 and x= 0.02 in $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1-x}Al_x)O_3$ (x= 0~0.1), the samples showed the relative densities above ${\geq}95%$ when those were sintered at ${\geq}1,350^{\circ}C$. In the case of the $x{\geq}0.06$ the sintered density deteriorated greatly at lower sintering temperatures. High temperature electrical conductivity of the samples decreased as the content of Al increased. Since the valence state of Al ion is unchangeable, while Cr or Co ions contribute to the electrical conduction by changing those valence states, Al substitution resulted in the decreased electrical conductivity. Al doping of LCCC was an effective way of decreasing the thermal expansion coefficient (TEC).

SOFC 연결재용 Al이 도핑된 (La0.8Ca0.2)(Cr0.9Co0.1)O3(LCCC)계 세라믹스의 합성 및 치밀화 특성

이호영,이준형,강보경,이호창,허영우,김정주,김재육 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.5

In the (La0.8Ca0.2)(Cr0.9Co0.1)O3 (LCCC), which has been using as interconnector materials in SOFC, Al ions were substituted for Co because ionic radius of Al is similar to that of Co. Because of the almost identical ionic radius of Al and Co, the substitution was not thought to be affect the tolerance factor of LCCC, and the densification behavior, high temperature electrical conductivity and thermal expansion coefficient were examined as a function of Al concentration. In the cases of the x= 0 and x=0.02 in (La0.8Ca0.2)(Cr0.9Co0.1-xAlx)O3 (x= 0∼0.1), the samples showed the relative densities above ≥95%when those were sintered at ≥1,350℃. In the case of the x≥0.06 the sintered density deteriorated greatly at lower sintering temperatures. High temperature electrical conductivity of the samples decreased as the content of Al increased. Since the valence state of Al ion is unchangeable, while Cr or Co ions contribute to the electrical conduction by changing those valence states, Al substitution resulted in the decreased electrical conductivity. Al doping of LCCC was an effective way of decreasing the thermal expansion coefficient (TEC). 고체 연료전지의 연결재로 사용되어온 (La0.8Ca0.2)(Cr0.9Co0.1)O3 (LCCC)에서 Co 이온반경과 거의 같아 치환을 하여도 LCCC의 tolerance factor에는 거의 영향을 주지 않을 것으로 생각되는 Al 이온을 Co 이온과 치환한 후 치환량에 따른 치밀화 거동, 고온 전기전도도, 열팽창거동을 조사하였다. (La0.8Ca0.2)(Cr0.9Co0.1-xAlx)O3 (x= 0∼0.1)에서 x= 0 및 x= 0.02 소결체의 경우, 1,350℃ 이상의 온도에서 95% 이상의 상대 밀도를 나타내었다. x≥0.06인 경우 저온에서는 소결밀도가 급격히 저하되어 치밀화에 악영향을 끼쳤다. 고온 전기전도도는 x값이 증가할수록 감소하는 거동을 나타내었다. 이것은 B-자리에 치환되는 Al 이온이 Cr이나 Co 이온과 같이 전자가 변화를 일으켜 전기전도에 기여할 수 없기에 일어난 현상으로 생각된다. 열팽창 계수는 Al 치환량이 증가할수록 감소하는 것으로 나타났다.

CMP 공정에서 슬러리와 웨이퍼 형상이 SiC 웨이퍼 표면품질에 미치는 영향

박종휘,양우성,정정영,이상일,박미선,이원재,김재육,이상돈,김지혜,Park, Jong-Hwi,Yang, Woo-Sung,Jung, Jung-Young,Lee, Sang-Il,Park, Mi-Seon,Lee, Won-Jae,Kim, Jae-Yuk,Lee, Sang-Don,Kim, Ji-Hye 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.4

The effect of slurry composition and wafer flatness on a material removal rate (MRR) and resulting surface roughness which are evaluation parameters to determine the CMP characteristics of the on-axis 6H-SiC substrate were systematically investigated. 2-inch SiC wafers were fabricated from the ingot grown by a conventional physical vapor transport (PVT) method were used for this study. The SiC substrate after the CMP process using slurry added oxidizers into slurry consisted of KOH-based colloidal silica and nano-size diamond particle exhibited the significant MRR value and a fine surface without any surface damages. SiC wafers with high bow value after the CMP process exhibited large variation in surface roughness value compared to wafer with low bow value. The CMPprocessed SiC wafer having a low bow value of 1im was observed to result in the Root-mean-square height (RMS) value of 2.747 A and the mean height (Ra) value of 2.147 A.