• 문화기술의 융합
• /
• 제9권6호
• /
• pp.855-859
• /
• 2023

질산구리삼수화물염(copper(II) nitrate trihydrate) 수용액을 공업용 전분(starch)에 함침 시킨 전구체를 이용하여 산화구리(CuO) 나노 입자를 합성하였다. 주사전자현미경(SEM)을 통하여 질산구리삼수화물염 수용액이 함침된 전구체에 대한 구조를 분석하였고, 전구체에 대한 열처리 온도를 증가 시킴에 따라 생성되는 산화구리 입자의 입자 크기와 결정 구조를 X선회절분석법(XRD)과 주사전자현미경(SEM)으로 분석하였다. 분석 결과에 따르면, 전구체에서 유기물질이 완전히 열분해 되어지는 온도는 450-490℃이며, 열처리하는 온도가 증가함에 따라 생성되는 산화구리 입자의 크기와 결정성이 증가하는 것을 확인할 수 있었고, 또한 500-800℃에서 1시간씩 열처리하여 얻은 산화구리 입자의 크기는 100nm-2㎛인 것으로 나타났다. 하소 온도 400℃에서 산화구리 결정상이 형성되고, 800℃까지는 산화구리 단일상만 존재하며, 하소 온도의 증가에 따라 생성되는 입자의 크기가 커지는 것을 확인하였다.

• 한국세라믹학회지
• /
• 제39권8호
• /
• pp.783-788
• /
• 2002

본 연구에서는 TMS[Tetramethylsilane:Si($CH_3)_4$], $NH_3$와 $H_2$를 이용하여 나노크기의 Si-C-N precursor 분말을 합성하기 위하여 CVC법을 이용하였으며 반응온도, TMS/$NH_3$ 비 그리고 TMS/$H_2$ 비를 변화시켰다. XRD와 FESEM 분석을 통해서 결정상과 입자의 크기 그리고 입자의 형태를 관찰하고자 하였으며, 그 결과 제조된 분말은 모든 실험 조건하에서 87∼130 nm 크기를 지닌 균일한 구형의 비정질 분말이 얻어졌다. 입자 크기는 반응온도의 감소에 따라 감소하였으며, 또한 TMS/$NH_3$, TMS/$H_2$ 비가 작아질수록 감소하였다. EA 분석 결과 제조된 분말은 Si, N, C, H로 이루어졌음을 알 수 있었으며 FT-IR를 통하여 Si-N, C-N, Si-C 결합을 가진 Si-C-N precursor 분말이 제조되었다

• Carbon letters
• /
• 제15권1호
• /
• pp.25-31
• /
• 2014

A microstructure analysis is carried out to optimize the process parameters of a randomly oriented discrete length hybrid carbon fiber reinforced carbon matrix composite. The composite is fabricated by moulding of a slurry into a preform, followed by hot-pressing and carbonization. Heating rates of 0.1, 0.2, 0.3, 0.5, 1, and $3.3^{\circ}C/min$ and pressures of 5, 10, 15, and 20 MPa are applied during hot-pressing. Matrix precursor to reinforcement weight ratios of 70:30, 50:50, and 30:70 are also considered. A microstructure analysis of the carbon/carbon compacts is performed for each variant. Higher heating rates give bloated compacts whereas low heating rates give bloating-free, fine microstructure compacts. The compacts fabricated at higher pressure have displayed side oozing of molten pitch and discrete length carbon fibers. The microstructure of the compacts fabricated at low pressure shows a lack of densification. The compacts with low matrix precursor to reinforcement weight ratios have insufficient bonding agent to bind the reinforcement whereas the higher matrix precursor to reinforcement weight ratio results in a plaster-like structure. Based on the microstructure analysis, a heating rate of $0.2^{\circ}C/min$, pressure of 15 MPa, and a matrix precursor to reinforcement ratio of 50:50 are found to be optimum w.r.t attaining bloating-free densification and processing time.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.85.2-85.2
• /
• 2010

$Cu_2ZnSnSe_4$ (CZTSe) is one of candidate to alternate $Cu(In,Ga)Se_2$ as solar absorber material for solar cell. The expensive elements of In and Ga are replaced by Zn and Sn, respectively to lower the material cost. In this study we fabricated CZTSe thin film by selenization of single precursor layer consisted metallic constituent. Precursor compositions ratio were selected to have Cu-poor and Zn-rich content and prepared by RF magnetron sputtering. Thermal processing was applied to introduce selenium into as-deposited films at temperatures ranging from 350 to 500 for time up to 120 minutes. Single precursor films showed amorphous structure and consist of individual elements of Cu, Zn, and Sn. It was confirmed by XRD analysis that synthesis of CZTSe compound is occurred from lower temperature process, although concurrently additional phases such as binary cooper selenides are also existed. The quality of CZTSe crystal was improved as temperature increased. We also investigated the optical and electrical properties of as-selenized CZTSe as well.

• Bulletin of the Korean Chemical Society
• /
• 제25권4호
• /
• pp.480-484
• /
• 2004

$LiGaO_2$ films have been grown on Si (100) substrates using a new single precursor $[Li(OCH_2CH_2OCH_3)_2-Ga(CH_3)_2]_2$ under high vacuum conditions $(5{\times}10^{-6}Torr)$. The $[Li(OCH_2CH_2OCH_3)_2Ga(CH_3)_2]_2$ was synthe-sized and characterized by using spectroscopic methods and single-crystal X-ray diffraction analysis. The chemical composition, crystalline structure, and morphology of the deposited films were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. The results show that polycrystalline $LiGaO_2$ films preferentially oriented in the [010] direction can be deposited on Si (100) at 500-550$^{\circ}C$ by metal organic chemical vapor deposition (MOCVD). The single precursor $[LiOCH_2CH_2OCH_3)_2-Ga(CH_3)_2]_2$ has been found suitable for chemical vapor deposition of $LiGaO_2$ thin films on Si substrates.

• Bulletin of the Korean Chemical Society
• /
• 제33권10호
• /
• pp.3383-3386
• /
• 2012

SnS thin films were deposited on glasses through metal organic chemical vapor deposition (MOCVD) method at relatively mild conditions, using bis(3-mercapto-1-propanethiolato) tin(II) precursor without toxic $H_2S$ gas. The MOCVD process was carried out in the temperature range of $300-400^{\circ}C$ and the average grain size in fabricated SnS films was about 500 nm. The optical band gap of the SnS film was about 1.3 eV which is in optimal range for harvesting solar radiation energy. The precursor and SnS films were characterized through infrared spectroscopy, nuclear magnetic resonance spectroscopy, DIP-EI mass spectroscopy, elemental analyses, thermal analysis, X-ray diffraction, and field emission scanning electron microscopic analyses.

• 한국재료학회지
• /
• 제4권4호
• /
• pp.472-476
• /
• 1994

질산납으로부터 침전법으로 제조된 PbO-전구체의 상변태를 열분석, X-선 회절, 적외선 흡수 및 Raman분광 분석 등을 통하여 조사하였다. 질산납 수용액으로부터 $45^{\circ}C$, pH 9.0의 반응조건에서 PhO-전구체를 제조하였다. 침전물은 hydrous lead oxynitrate와 lead hydroxynitrate의 혼합체이었다. $560^{\circ}C$까지 열처리온도가 증가함에 따라 전구체는 $3Pb(NO_{3})_{2}$ㆍ7PbO를 거쳐 $Pb(NO_{3})_{2}$ㆍ5PbO로 된 후에 PbO(litharge)로 변화되었으며, $560^{\circ}C$이상에서 최종적으로 massicot형의 PbO로 변태되었다.

• 한국세라믹학회지
• /
• 제33권12호
• /
• pp.1387-1393
• /
• 1996

A study on mesophase pitch as a matrix precursor of carbon fiber reinforced carbon (C/C) composite has been recently presented. This study is concerned with the production of mesophase pitch as matrix precursors for C/C composite from coal tar pitch. A commercial coal tar pitch was heat-treated at 25$0^{\circ}C$ for 2 hours to remove low molecular weight fraction from the pitch then increasing the temperature of the pitch to between 350~45$0^{\circ}C$ to produce mesophase pitch. The pitch was continuously stirred during this time and nitrogen gas was continuously bubbled through the pitch. Spherical and bulk mesophases were formed in the pitch after heat-treatment,. Parent and mesophae pitches were characterized by elemental analysis coke yield solubi-lity in tetrahydrofuran and hexane and an optical microscopy to measure the mesiophase content. It was neces-sary to produce C/C composite that a mesophase pitch with about 30-40 vol% mesophase spherulites can be infiltrated into a fiber preform without a filter effect as a matrix precursor conditions. This condition was satisfied with mesophase pitch heat treated at 40$0^{\circ}C$ for 2 hours. The other heat treatment conditions showed the nuclei of mesophase or bulk mesophae which were not satisfied with the matix precursor condition.

• The Korean Journal of Ceramics
• /
• 제6권1호
• /
• pp.32-36
• /
• 2000

Pyrolytic preparations of Ti-Al-N ceramics from three blended precursors were investigated. The precursors were prepared stirring ($HA1N^{i}Pr_m$ and an aminolysis product of $Ti(NMe_2)_4$ with $MeHNCH_2CH_2$NHMe in $C_6/H_6$ . IR and $^1H\;NMR $analyses suggested that essentially no Ti-N-Al bonds were present in the precursors. Pyrolysis of the precursors under $NH_3-N_2$led to the formation of brown solids with ceramic yields of about 30%, and the Ti-Al ratios in the pyrolyzed products were close to those of the precursors. XRD analysis of the pyrolyzed product from the precursor with Ti:Al=5:1 indicated the formation of a NaCl-type compound as the only crystalline phase. Pyrolysis of the precursor with Ti:Al=2:1 led to the formation of AlN besides the major NaCl-type compound. A ceramic composite containing AlN and the NaCl-type compound was formed by pyrolysis of the precursor with Ti:Al=1:2.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.381.2-381.2
• /
• 2014

In this study the amorphous carbon films were deposited by PECVD at the substrate temperature range of 250 to $600^{\circ}C$, and the process conditions of higher and lower precursor flow rate, respectively. The temperature was a main parameter to control the density and mirco-structures of carbon films, and their's properties depended with the process temperatrue are changed by controlling precursor flow rate. The precursor feeding rate affect on the plasma ion density and a deposition reactivity. This change of film properties was obtained the instrinsic stress, FT-IR & Raman analysis, refractive index (RI) and ext. coef. (k) measured by ellipsometer. In the process conditions of lower and higher flow rate of precursor it had a different intrinsic stress as a function of the substrate temperature.