Materials Literature
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본 연구에서는 초경량성 마그네슘 재료를 엔진 블록, 실린더 헤드커버 등과 같은 박용기관에 적용하기 위한 환경 친화적 표면처리의 개발에 대하여 고찰하였다. 또한 이온플레이팅법에 의해 마그네슘 박막을 제작하고, 그 제작조건에 따라 변화하는 막의 결정배향성과 몰포로지가 경도특성에 미치는 영향을 해명하고자 하였다. 마그네슘 박막의 경도측정 결과, 아르곤 가스압의 증가에 따라 그 경도값이 상승하였는데, 그 원인은 결정립계에 의한 강화와 성분 외 가스입자의 흡장효과에 의한 것으로 사료된다.
Abstract In this study thin film samples of Ga1‐xMnxN were grown by pulsed laser deposition on Al2O3 (0001) substrates. X‐ray diffraction measurements have confirmed these thin films exhibit hexagonal wurtzite structure. SQUID measurements show room temperature ferromagnetism of these dilute magnetic semiconductors (D…
Abstract In this work we study the optical properties of two high quality fifty‐periods of In‐polarity InN/In0.73Ga0.27N MQWs samples, grown by radio‐frequency plasma‐assisted molecular beam epitaxy, with different well (0.5‐1 nm) and barrier thicknesses (3‐4 nm). We employ spectroscopic ellipsometry at room temperatu…
We present the synthesis and detailed characterization of RbxMn[Fe(CN)]6 and Mn3[Cr(CN)6]2 compounds. The composition of the materials significantly depends on the preparation conditions. Analysis of Raman spectroscopic results and X-ray powder diffraction data yielded a further assessment of the changes in structural…
[ $CeO_2$ ]has been widely used for single buffer layer of coated conductor because of superior chemical and structural compatibility with $ReBa_2Cu_3O_{7-{\delta}}$ (Re=Y, Nd, Sm, Gd, Dy, Ho, etc.). But, the surface of $CeO_2$ layer showed cracks because of the large difference in thermal expansion coefficient betwee…
Studies on the use of polydimethylsiloxane to align liquid crystals have been carried out. The thin films prepared using the silicon-based elastomer, with a pretty low surface free energy, are found to be capable of vertically aligning liquid crystals. The pretilt angle of calamitic liquid crystals sandwiched between…
Abstract The title compound is prepared by addition of stoichiometric amounts of (NH4)2CO3 to an aqueous solution of H4P2O6.
열적 안정성과 기계적 강도에서 우수한 장점을 지니고 있는 파라계 aramid 세그먼트와 제막 특성이 우수하고 내가수분해성이 우수한 sulfone 세그먼트로 이루어진 공중합체를 이용하여 연료 전지용 막으로써의 응용가능성을 연구하였다. 아라미드 고분자의 용해도를 향상시키기 위해 아민기를 갖는 sulfonated ether sulfone 단량체와 p-phenylene diamine 그리고 terephthaloyl chloride를 일정한 순서로 반응시켜 아민으로 말단화된 공중합체를 합성하고, 이것을 epoxy group을 함유하고 있는 trimethylolpropane…
We report on the synthesis and characterizations of TiO 2 nanoparticles embedded in polyamide-6 composite nanofibers by using electrospinning technique. The influence of substrate on the electrical characteristics of polyamide-6/TiO 2 composite nanofibers was investigated. The resultant nanofibers exhibit good incorpo…
One-dimensional CdS@TiO 2 core-shell heterostructures were fabricated via the hydrolysis of tetrabutyl titanate (TBT) on preformed CdS nanowires. The as-prepared products were characterized by X-ray diffraction, transmission electron microscopy, selected area electron diffraction and diffuse reflectance spectroscopy t…
Due to the limitations of polysilicon, in particular, its lack of flexibility in biomedical applications and its expensive processing cost, numerous studies have been undertaken to investigate alternate materials for microelectromechanical processing and applications. Therefore, polymeric materials like polymethylsilox…
One-dimensional (1-D) nanomaterials with superior specific capacity, higher rate capability, better cycling peroperties have demonstrated significant advantages for high-performance Li-ion batteries and supercapacitors. This review describes some recent developments on the rechargeable electrodes by using 1-D nanomate…
방향족 액정 폴리에스테르는 열방성 액정 중합체의 대표적인 예로 지금까지 구조-물성 관계가 많이 연구되었다. 본 연구에서는 유기 용매에 녹일 수 있는 가용성 방향족 액정 폴리에스테르를 합성하고 아세틸렌 말단기를 갖는 열경화성 수지와 복합화하여 제반 물성을 비교하였다. 가용성 방향족 액정 폴리에스테르는 6-hydroxy-2-naphthoic acid, terephthalic acid, isophthalic acid 및 4-aminophenol을 단량체로 하여 에스테르 및 아미드 교환 반응에 기초로 한 축합 중합법을 이용하여 합성하였다. 아세틸렌 말단기를 갖는 열경화성…
Silicotungstic acid (H4O40SiW12) was supported on SBA-15 with the content of 20% by impregnation. The structure and proper-ties of the catalyst were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption-desorption, and transmis-sion electron microscopy. H4O40SiW12 was highly disper…
An in situ carbothermal process has been utilized to successfully convert sputtered (0001) oriented ZnO nanofilm into large scale [011̅0] directed nanowires at 800−900 °C in a tubular reaction chamber. To understand the conversion process and unravel the driving force behind this growth phenomenon, a comparative study…
본 연구에서는 페닐아세테이트를 core 물질로 하고 poly(urea-formaldehyde)를 캡슐막 구성물질로 하는 미세캡슐의 제조에 있어서, 교반속도, core/shell 질량비, 계면활성제 농도, 반응시간 등의 공정변수가 캡슐의 크기, 막두께, 표면형태 등의 특성에 미치는 영향을 조사하였다. FTIR 및 TGA에 의하여 원하는 미세캡슐이 제조되었음을 확인하였다. 캡슐의 특성은 광학현미경과 FE-SEM을 사용하여 분석하였다. 교반속도의 증가에 따라 캡슐의 크기와 막두께가 감소하는 것으로 나타났다. 캡슐막 구성물질 질량의 증가는 캡슐막의 두께와 막표면에 부착되는…
A silica aerogel sheet with a very low thermal conductivity is used to suppress the temperature increase of the Cu coil in an induction cooker by reducing the heat flow from the heat source (cooking pot). It is found that the temperature of the Cu coil is reduced significantly by the insertion of an insulation sheet b…
The current investigation was fulfilled for insight into the dielectric properties of Tl4S3layered single crystals. The real part of dielectric constant e׳, imaginary part of dielectric constant e×´, the dissipation factor tan δ and the alternating current conductivity σac were measured in an applied ac electric fiel…
Thiacalix[4]arenes bearing one, three, or four P˭O containing groups at the upper or at the lower rim have been synthesized. Stereochemistry of the compounds was investigated by X-ray method.
In this study, the magnetic properties of CoFeSiB glass covered amorphous wires (GCAWs) concerning their anisotropy, susceptibility, and coercivity have been investigated. The microscopic hysteresis loops of GCAWs of different lengths ranging from 1 to 40 mm and different metallic diameters ranging from 7 to 30 μm, fa…