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Sol-Gel 반응을 통한 Surlyn/유기 실리케이트 나노복합재료 제조 및 물성에 관한 연구
차종현,정희정,서길수 한국공업화학회 2003 응용화학 Vol.7 No.2
Transparent organic-inorganic hybrid material was synthesized via the sol-gel method using polyethylene-co-methacrylic acid(PEMA) ionomer and a metal alkoxide, tetraethylorthosilicae(TEOS). The resulting material was characterized using ^(29)Si solid-state nuclear magnetic resonance spectroscopy results prove that silica is formed via the sol-gel reaction. Scanning electron microscopy analysis (SEM) , transmission electron microscopy (TEM) studies indicate that silica particle size is in nanoscopic level (70nm average size), and silica nanoparticles are uniformly dispersed in the polymer matrix after the sol-gel process. Theremogravimetric analysis (TGA) results show that the silica content of the hybrid. The thermal stability of the ionomer increases after hybridization. Material testing machine of the hybrid shows that the stress of ionomer increase after the sol-gel reaction.
Cha, Hyun Gil,Kim, Young Hwan,Kim, Chang Woo,Kang, Young Soo,Kwon, Hae Woong TaylorFrancis 2007 Molecular Crystals and Liquid Crystals Vol.464 No.1
<P> Thermal decomposition process was applied to synthesize Fe3O4 and Nd2Fe14B nanoparticles which were prepared by reduction diffusion process for preparing exchange-coupled nanoparticles. The magnetic Nd2Fe14B nanoparticles used in this study as the starting materials were synthesized via metal oleate complex method. Also mechanical ball mill technique was applied to the mixture of magnetic Nd2Fe14B and α-Fe nanoparticles to build an exchange-coupled nanoparticle. The mixture of Nd2Fe14B/α-Fe of nanoparticle was confirmed by transmission electron microscopy (TEM). The crystal structure of nanoparticle was characterized by X-ray diffraction pattern (XRD). The magnetic properties were characterized with saturation magnetization from hysteresis loop by vibrating sample magnetometer (VSM). Thermogravimetry using a microbalance with magnetic field gradient positioned below the sample was used for the measurement of a thermomagnetic analysis (TMA) curve showing the downward magnetic force versus temperature.</P>
Manual assembly of nanocrystals for enhanced photoelectrochemical efficiency of hematite film
Cha, Hyun Gil,Kang, Myung Jong,Hwang, In Chul,Kim, Hyunsung,Yoon, Kyung Byung,Kang, Young Soo The Royal Society of Chemistry 2015 Chemical communications Vol.51 No.29
<P>To improve the optoelectronic properties of hematite film as a photoanode, hematite film was orientated on the (012) plane by the secondary growth of organized microcrystals. The resultant film showed promising photoelectrochemical effects compared with a randomly oriented one, with a maximum photocurrent of 0.8 mA cm<SUP>−2</SUP> at 1.23 V <I>vs.</I> RHE under the illumination of 1 sun.</P> <P>Graphic Abstract</P><P>A (012) plane oriented hematite film with secondary growth of organized microcrystals showed promising photoelectrochemical efficiency compared with a randomly oriented film. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5cc00200a'> </P>
Magnetic property of Sm-Co nanoparticles prepared by solution phase metal salt reduction.
Cha, Hyun Gil,Kim, Chang Woo,Ji, Eun Sun,Kang, Dong In,Kang, Young Soo American Scientific Publishers 2009 Journal of nanoscience and nanotechnology Vol.9 No.12
<P>Sm-Co magnetic nanoparticles were successfully synthesized at high temperature above 680 degrees C in solution phase. The chemical composition was determined by EDX and it was found that the composition of as-synthesized Sm-Co magnetic nanoparticles showed less Sm content compared with the composition of starting materials. From TEM and FE-SEM measurements, the morphology of as-synthesized and heat-treated Sm-Co a magnetic nanoparticle was confirmed as hexagon and apatite crystal structure. Curie temperature was observed at around 680 degrees C correspond to SmCo5 phase. The magnetic property was measured by VSM and shows the ferromagnetic characteristics.</P>
Photocatalysis: progress using manganese-doped hematite nanocrystals
Cha, Hyun Gil,Noh, Hyun Seok,Kang, Myung Jong,Kang, Young Soo The Royal Society of Chemistry 2013 New journal of chemistry Vol.37 No.12
<P>Manganese-doped hematite nanocrystals were synthesized by hydrothermal method and study on the activity of photocatalytic properties by different Mn ratio. From the crystal structure and optical study, the oxidation state of the manganese-doped hematite crystals was modulated by doping. The activity of samples (M1–M3) was tested by photodegradation of methyl orange dye in the presence of manganese-doped hematite as photocatalyst.</P> <P>Graphic Abstract</P><P>Manganese doping in hematite crystals leads to higher photocatalytic activity compared to pure hematite crystals. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3nj00478c'> </P>
Preparation and Characterization of Soft Phase Magnetic α-Fe Nanoparticles by Different Methods
Cha, Hyun Gil,Kim, Young Hwan,Lee, Don Keun,Jeong, In Chul,Kwon, Hae Woong,Kang, Young Soo Scitec Publications Ltd. 2007 Solid State Phenomena Vol.119 No.-
<P>The magnetic α-Fe nanoparticles were carried out using two-preparation methods that include solution phase metal salt reduction and organometallic precursor decomposition. Under the different reaction conditions such as precursor and reaction time, the magnetic properties of α-Fe nanoparticles were studied. The size of nanoparticle was confirmed by transmission electron microscope (TEM) images. The magnetic properties were characterized with saturation magnetization(Ms) from hysteresis loop by vibrating sample magnetometer (VSM). The crystallinity and structure of α-Fe nanoparticles was investigated by X-ray diffraction (XRD).</P>
Cha Hyun-Ju,Cho, Yeong-Gil The Korean Society of Oceanography 2002 Journal of the Korean Society of Oceanography Vol.37 No.2
Temporal variation of nutrients and dissolved major and trace elements have been studied in the Yeongsan River, Korea. There were significant temporal fluctuations in the concentrations of these elements depending upon the flow condition. $NH_4$, $PO_4$, Na, Mg, Ca, K, Mn, Cu, Ni, Zn, Co, As and U concentrations were inversely related to the flow; that is, they are the highest at low flow and the lowest at high flow. It indicates that these elements are derived from point sources such as rock weathering and/or human activities and then diluted by increasing flow. Meanwhile, Fe and Si concentrations varied proportionally to the flow indicating that they are derived from diffuse sources including reactions within soil. The concentration-flow relationships showed that hydrology of the river is the most important factor controlling the chemical composition of the Yeongsan riverwater, which was compatible of the results of R-mode factor analysis.