• 자원환경지질
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• 제45권2호
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• pp.181-188
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• 2012

일라이트에서 적층방식을 달리하여 나타나는 폴리타입은 대부분 1M과 $2M_1$이며, 적층 Disordering에 따른 $1M_d$ 또한 흔히 관찰된다. 본 해설에서는 일라이트의 폴리타입을 구분하고 정량적으로 해석할 수 있는 광물학적 이론적 근거와 방법을 소개하고, 소규모 열수환경에 준하는 단층대 내 생성시기 및 조건을 달리하는 일라이트 폴리타입 혼합물에의 적용을 통한 단층 활동 및 재활동연대 결정에의 활용 가능성을 검토하였다. 단층연대해석의 정확도와 신빙도를 높이기 위해서는 단층암 대상시료 내 일라이트 폴리타입의 생성환경에 대한 정보, 동정 및 광물학적 특성에 대한 규명이 이루어져야 한다. 또한 WILDFIRE(C)시뮬레이션을 이용한 정량분석에서, $1M_d$ 폴리타입의 Disordering 정도 및 I/S 광물의 팽창도에 기인한 (hkl) 회절선들의 Broadening 효과 등 일라이트 폴리타입 정량분석법의 오차요인을 최소화시키는 하기 방법을 고려해야 할 것이다.

• 한국세라믹학회지
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• 제26권1호
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• pp.31-36
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• 1989

In order to synthesize AlN-polytypes from AlN-SiO2-Al2O3 system, composition A (AlN/SiO2/Al2O3=1/0.3/0.05, mole ratio) and composition B(AlN-SiO2-Al2O3=1/0.2/0.05, mole ratio) were used. AlN-polytypes were produced by nitriding the mixture at 175$0^{\circ}C$~190$0^{\circ}C$ under N2 atmosphere. For lower reaction temperature, 15R phase was produced and in the case of higher reaction temperature, AlN phase was only produced. As each composition was heated at 185$0^{\circ}C$ in N2 atmosphere, produced main phases were 15R phase for composition A and 21R phase for composition B respectively. The fracture surfaces of produced reactants showed porous skeleton structure.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.433-433
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• 2011

Since the concept of graphene was established, it has been intensively investigated by researchers. The unique characteristics of graphene have been reported, the graphene attracted a lot of attention for material overcomes the limitations of existing semiconductor materials. Because of these trends, economical fabrication technique is becoming more and more important topic. Especially, the epitaxial growth method by sublimating the silicon atoms on Silicon carbide (SiC) substrate have been reported on the mass production of high quality graphene sheets. Although SiC exists in a variety of polytypes, the 3C-SiC polytypes is the only polytype that grows directly on Si substrate. To practical use of graphene for electronic devices, the technique, forming the graphene on 3C-SiC(111)/Si structure, is much helpful technique. In this paper, we report on the growth of graphene on 3C-SiC(111) surface. To investigate the morphology of formed graphene on the 3C-SiC(111) surface, the radial distribution function (RDF) was calculated using molecular dynamics (MD) simulation. Through the comparison between the kinetic energies and the diffusion energy barrier of surface carbon atoms, we successfully determined that the graphitization strongly depends on temperature. This graphitization occurs above the annealing temperature of 1500K, and is also closely related to the behavior of carbon atoms on SiC surface. By analyzing the results, we found that the diffusion energy barrier is the key parameter of graphene growth on SiC surface.

• 한국광물학회지
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• 제14권2호
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• pp.119-127
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• 2001

주구성 양이온이 Si와 Al인 딕카이트와 엽납석에 대하여 적외선분광분석(FTIR)을 실시하였다. 원적외선(Far-IR)영역과 중간적외선(Mid-IR)영역을 이용하였으며, 특히 $200 cm^{-1}$ / 이하의 Far-IR영역에서 처음으로 딕카이트의 흡수선들을 제시하였다. 딕카이트의 경우 일부 시료에서 소량의 카올리나이트나 나크라이트 층이 소량으로 협재되어 있다. 카올리나이트의 결정도를 나타내는 Hinckley지수는 딕카이트의 결정도와는 관련성이 적게 나타났다. 엽납석의 경우, 수산기와 관련된 신축진동흡수띠($3673~3676 cm^{-1}$ )는 약간 이상적인 구조에서 벗어나 있는데, 아마도 미량의 철에 의한 영향이나, 삼사형과 단사형이 섞여 있기 때문인 것으로 보인다.

• 반도체디스플레이기술학회지
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• 제14권1호
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• pp.27-30
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• 2015

SiC based Schottky barrier diodes were prepared by using the facing targets sputtering method. In this research, 4H-SiC polytypes of SiC were adopted and Molybdenum, Titanium was employed as the Schottky metal of the metal-semiconductor contacts. Both structures showed the rectifying nature in their forward and reverse J-V characteristic curve and the ideality factors calculated from these plots that were close to unity were represented the nearly ideal behavior. Difference of Schottky barrier height between prepared devices was also corresponding with the electrical characteristics of themselves. Therefore the suitability of the facing targets sputtering method for fabrication of Schottky diodes could be suggested from these results.

• Journal of Photoscience
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• 제6권4호
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• pp.183-186
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• 1999

We have been prepared the porous silicon carbide (PSC) by electrochemical etching of silicon carbide single crystals. Samples of PSC have been studied by the methods of scanning electron microscope (SEM) and photoluminescence (PL). Two PL bands attributed to the blue and green light emission were observed in this study. According to the anodization conditions, the main source of emission in the oxidized layers of PSC lies in the different surface defect centers which consist of different geometrical structures due to the polytypes. It means that origin of these PL bands may be existed in different size pores simultaneously. The present results indicate that the high energy band comes from the top porous layers while the low energy band comes from the lower porous layers.

• 자원환경지질
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• 제29권4호
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• pp.471-481
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• 1996

Clay mineral geothermometry using sericites and chlorites in Bobae sericite mine reveals that these clay minerals formed at relatively high temperature. It appears that sericites formed at around $200{\sim}350^{\circ}C$ and chlorites formed at around $250^{\circ}C$. X-ray diffraction study of these minerals reveals that sericite $2M_1$ type and chlorite IIb type are dominant phases. Both polytypes indicate that the precipitation temperatures of these minerals shows fairly good agreement with the estimated temperature by clay mineral geothermometry. The Bobae sericite mine was formed at relatively higher temperature than several non-metal ore deposits occurred in the southern part of Korea.

• 자원환경지질
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• 제29권4호
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• pp.447-454
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• 1996

Clay mineral geothermometry using sericites and chlorites in Bobae sericite mine reveals that these clay minerals formed at relatively high temperature. It appears that sericites formed at around $200{\sim}350^{\circ}C$ and chlorites formed at around $250^{\circ}C$. X-ray diffraction study of these minerals reveals that sericite 2M, type and chlorite lib type are dominant phases. Both polytypes indicate that the precipitation temperatures of these minerals shows fairly good agreement with the estimated temperature by clay mineral geothermometry. The Bobae sericite mine was formed at relatively higher temperature than several non-metal ore deposits occurred in the southern part of Korea.

• 한국광물학회지
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• 제11권2호
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• pp.69-84
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• 1998

The Daehyun sericite deposit in socheon-myun, Bongwha-gun, Kyungsangbuk-do, Korea, has been formed by the hydrothermal alteration of the Hongjesa granite of Precambrian age, leaving the muscovite granite between ore body and the Hongjesa granite as the wall rock alteration zone. The process of sericitization of granitic rock as well as chemistry and structures of sericites were studied using polarizing microscope, X-ray diffractometer (XRD), electron probe microanalyzer (EPMA) and high resolution transmission electron microscope (HRTEM). There are two genetic types of sericites having different chemistry and structure. The early sericite is of 2M1 polytype and has octahedral composition close to muscovite. It has been formed from the primary muscovite, tourmaline and quartz under a relatively high temperature. The late sericite is of 1M, 2M1 and 3T polytypes and has phengitic composition. It has been formed form feldspar, biotite, muscovite and tourmaline under a relatively low temperature. Chemical analyses show t, the early sericite has less Mg+FeT content and lower Si/AlIV ratio in tetrahedral site than the late sericite.

• The Korean Journal of Ceramics
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• 제2권3호
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• pp.152-156
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• 1996

Fine (~0.09 $\mu$m) $\beta$-SiC Powders with 3.3wt% of large (~0.44$\mu$m) $\alpha$-SiC of $\beta$-SiC particles (seeds) added were hotpressed at 175$0^{\circ}C$ using $Y_2O_3$, $Al_2O_3$ and CaO as sintering aids and then annealed at 185$0^{\circ}C$ for 4 h to enhance grain growth. The resultant microstructure and polytypes were analyzed by high resolution electron microscopy (HREM).Growth of $\beta$-SiC with high density of microtwins and formation of ${\alpha}/{\beta}$ composite grains consisting of $\alpha$-SiC domain sandwiched between $\beta$-SiC domains were found in both specimens. When large $\alpha$-SiC (mostly 6H) seeds were added, the $\beta$-SiC transformend preferentially to the 6H polytype. In contrast, when large $\beta$-SiC (3C) seeds were added, the fine $\beta$-SiC transformed preferentially to the 4H polytype. Such results suggested that the polytype formation in SiC was influenced by crystalline form of seeds added as well as the chemistry of sintering aids. The ${\alpha}/{\beta}$ interface played and important role in the formation of elongated grains as evidenced by presence of ${\alpha}/{\beta}$ composite grains with high aspect ratio.