• Title, Summary, Keyword: Microwave microscopy

Search Result 109, Processing Time 0.041 seconds

Dielectric Properties and Microstructure Observation of Complex Perovskite (1-x)$(Li_{1/2}Sm_{1/2})TiO_3-x (Na_{1/2}Sm_{1/2})TiO_3$(LNST) system [1] (복합 페로브스카이트 (1-x)$(Li_{1/2}Sm_{1/2})TiO_3-x (Na_{1/2}Sm_{1/2})TiO_3$(LNST) system의 유전특성 및 미세구조 관찰 [1])

  • Son, Jin-Ok;Lee, Hwack-Joo;Nahm, Sahn
    • Applied Microscopy
    • /
    • v.34 no.1
    • /
    • pp.61-69
    • /
    • 2004
  • The microwave dielectric properties and microstructures of the Complex Perovskite (1-x)$(Li_{1/2}Sm_{1/2})TiO_3-x (Na_{1/2}Sm_{1/2})TiO_3$(LNST) system were investigated using the X-ray diffraction (XRD) and scanning electron microscopy (SEM). LNST had not only the antiphase tilting of oxygen octahedron but also the inphase tilting of oxygen octahedron and the antiparallel shift of cations. Also, when $0.0{\leq}x{\leq}0.4$, LNST had the vacancy ordering of A-sites because of the evaporation of Li ions. From the observation of the microstructure, abnormal grain growth phenomena were observed over the whole range of x. The temperature coefficient of resonant frequency ($T_{cf}$) of the $({Li_{1/2}}^{+1}{Sm_{1/2}}^{+3})TiO_3$(LST) system has a large negative value ($-220ppm/^{\circ}C$) but the $({Na_{1/2}}^{+1}{Sm_{1/2}}^{+3})TiO_3$(NST) system which substituted $Na^{+1}$ has a large positive value ($+173ppm/^{\circ}C$). The dielectric properties of ${\varepsilon}_r=103,\;Q*f_{0}=3,700GHz$ and $T_{cf}=+50ppm/^{\circ}C$ at 4GHz were obtained when x =0.4.

Investigation of the interface between diamond film and silicon substrate using transmission electron microscopy (투과 전자 현미경을 이용한 다이아몬드 박막과 실리콘 기판의 계면 연구)

  • 김성훈
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.10 no.2
    • /
    • pp.100-104
    • /
    • 2000
  • Diamond film was deposited on Si substrate by using microwave plasma-enhanced chemical vapor deposition (MPECVD) system. After thinning the cross section between diamond film and Si substrate by ion milling method, we investigated its interface via transmission electron microscopy We could observe that the diamond film was grown either directly on Si substrate or via the interlayer between diamond film and Si substrate. Thickness of the interlayer was varied along the cross section. The interlayer might mainly composed of Sic andlor amorphous carbon. We could observe the well-developed electron diffraction pattern of both Si and diamond around the interface. Based on this result, we can conjecture the initial growth behavior of diamond film on Si substrate.

  • PDF

Effect of FTO coated on stainless steel bipolar plate for PEM fuel cells

  • Park, Ji-Hun;Jang, Won-Yeong;Byeon, Dong-Jin;Lee, Jung-Gi
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • /
    • pp.55.2-55.2
    • /
    • 2009
  • A polymer electrolyte membrane (PEM) fuel cell has been getting large interest as a typical issue in useful applications. The PEMFC is composed of a membrane, catalyst and the bipolar plate. SnOx:F films on SUS316 stainless steel were prepared as a function of substrate with using electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) in order to achieve the corrosion-resistant and low contact resistance bipolar plates for PEM fuel cells. The SnOx:F films coated on SUS316 substrate at surface plasma treatment for excellent stability, before/after heat treatment for good crystalline structure and microwave power for were characterized by X-ray diffraction (XRD), auger electron microscopy (AES) and field emission-scanning electron microscopy (FE-SEM). The SnOx:F film coated on SUS316 substrate with various process parameters were able to observe optimum interfacial contact resistance (ICR) and corrosion resistance. It can be concluded that fluorine-doping content plays an important function in electrical property and characteristic of corrosion-protective film.

  • PDF

Preparation of [C60]Fullerene-CoS2 Nanocomposites and Kinetics Study for Photocatalytic Degradation of Organic Dyes

  • Kim, Jae Jin;Ko, Weon Bae
    • Elastomers and Composites
    • /
    • v.51 no.1
    • /
    • pp.49-55
    • /
    • 2016
  • Nanosized cobalt disulfide ($CoS_2$) particles were synthesized with 0.08 M cobalt chloride hexahydrate ($CoCl_2{\cdot}6H_2O$) and 0.2 M sodium thiosulfate pentahydrate ($Na_2S_2O_3{\cdot}5H_2O$) dissolved in distilled water under microwave irradiation. $[C_{60}]Fullerene-CoS_2$ nanocomposites were prepared with nanosized $CoS_2$ particles and [$C_{60}$]fullerene as heated by $700^{\circ}C$ for 2 h in an electric furnace. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) identified the heated $[C_{60}]fullerene-CoS_2$ nanocomposites. Heated $[C_{60}]fullerene-CoS_2$ nanocomposites were investigated the activity of photocatalytic degradation as a catalyst in various organic dyes like acid yellow 23, methylene blue, methyl orange, and rhodamine B with ultraviolet light at 254 nm by UV-vis spectrophotometer.

Study on the synthesis and the frequency response of HTS microwave device fabricated by pulsed laser deposition (레이저 공정을 이용한 초전도 통신소자 제작과 고주파특성 연구)

  • Park, Joo-Hyung;Jeong, Young-Sik;Lee, Sang-Yeol
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.288-290
    • /
    • 1997
  • Pulsed laser ablation has been used to fabricate superconducting $YBa_2Cu_3O_{7-x}$(YBCO) thin films on MgO substrates. The epitaxial YBCO thin films were grown at $750^{\circ}C$ and oxygen partial pressure of 200 mTorr. The electrical property and the characteristics of the YBCO thin films have been studied by R-T measurement. scanning electron microscopy (SEM) and X-ray diffraction (XRD). A microstrip line resonator has been fabricated using YBCO superconducting thin films by photolithography and wet-etch process. The resonator has linear microstrip line separated by a gap of 0.278 mm. We observed a fundamental resonance peak at the frequency of 10.007 GHz.

  • PDF

A Study on the Development of Automatic Welding System using Solor Energy (태양에너지를 이용한 자동용접 시스템 개발에 관한 연구)

  • Kim I.S.;Kim O.S.;Son J.S.;Seo J.H.
    • Proceedings of the KIPE Conference
    • /
    • /
    • pp.532-533
    • /
    • 2006
  • In this research work attempts were made to study the bonding of thermoplastics with adhesives using solar energy. In order to study the curing behaviour necessary experiments were conducted under varying conditions of temperature, exposure time and power. The cured samples were then studied under the optical microscope before subjecting to tensile testing in order to study their mechanical properties. The fracture surfaces were further studied under the Scanning Electron Microscopy in order to study the microstructural changes that are taken place during curing. From the present study it is evident that curing under higher solar energy temperature, generally improves bond strength and quality of the adhesive joints when compared to other modes of curing process expect the microwave curing process.

  • PDF

Terahertz dielectric characteristics of (Ba,Sr)$TiO_3$ thin films (테라헤르츠 영역에서의 BST 박막의 유전 특성 평가)

  • Cho, Kwang-Hwan;Kang, Chong-Yun;Yoon, Seok-Jin;Lee, Young-Pak;Maeng, In-Hee;Son, Joo-Hiuk
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.28-28
    • /
    • 2007
  • Ferroelectric $(Ba_{0.5}Sr_{0.5})TiO_3$ (BST) thin films of thickness 500nm were deposited on $LaAlO_3$, (LAO) substrates by at $800^{\circ}C$. BST films were characterized for structure using X-ray diffraction (XRD). The surface morphology and thickness of BST the films were characterized by atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM). We measured the dielectric properties at microwave frequencies (1~3 GHz) using a symmetrical stripline resonator with shorted ends and terahertz frequencies (0.2~2.5 THz) using a time-domain terahertz spectroscopy. The real and imaginary parts of the complex dielectric constant of the BST thin films on LAO substrates were in agreement with those previously reported.

  • PDF

Nickel Nanoparticles: An Ecofriendly and Reusable Catalyst for the Synthesis of 3,4-Dihydropyrimidine-2(1H)-ones via Biginelli Reaction

  • Sapkal, Suryakant B.;Shelke, Kiran F.;Shingate, Bapurao B.;Shingare, Murlidhar S.
    • Bulletin of the Korean Chemical Society
    • /
    • v.31 no.2
    • /
    • pp.351-354
    • /
    • 2010
  • Nickel nanoparticles (Ni NPs) appeared to exhibit the catalytic activity in one-pot cyclocondensation reaction for the preparation of 3,4-dihydropyrimidine-2(1H)-ones via Biginelli reaction from aromatic/heteroaromatic/aliphatic aldehydes, urea/thiourea and ethyl acetoacetate under microwave irradiation has been described. The UV absorbance spectra showed metallic Ni characteristics and appreciate with the particle size determined by Transmission electron microscopy (TEM). After reaction course the Ni NPs can be re-covered and reused without any apparent loss of activity.

Synthesis, Characterization and Catalytic Application of MoO3/CeO2-ZrO2 Solid Heterogeneous Catalyst for the Synthesis of Benzimidazole Derivatives

  • Rathod, Sandip B.;Lande, Machhindra K.;Arbad, Balasaheb R.
    • Bulletin of the Korean Chemical Society
    • /
    • v.31 no.10
    • /
    • pp.2835-2840
    • /
    • 2010
  • A series of $MoO_3/CeO_2-ZrO_2$ catalysts with different Mo content (8 - 20 wt %) were prepared by simple co-precipitation followed by impregnation method and were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), energy dispersive spectroscopic (EDS) techniques. The prepared materials were tested for catalytic activity by the synthesis of benzimidazole derivatives using condensation of aromatic aldehydes and o-phenylenediamine by conventional and microwave method. Obtained results reveal that the catalytic activity increases with increase in Mo wt % loading. The best catalytic activity was obtained with 20 wt % $MoO_3/CeO_2-ZrO_2$. The particle size or crystallite size was estimated using Debye-Scherrer equation. After completion of reaction, the catalyst can be recovered efficiently and reused with consistent activity.

Thermal Properties of Diamond Films Deposited by Chemical Vapor Depositon

  • Chae, Hee-Baik;Baik, Young-Joon
    • The Korean Journal of Ceramics
    • /
    • v.3 no.1
    • /
    • pp.29-33
    • /
    • 1997
  • Four diamond films were deposited by the microwave plasma assisted chemical vapor deposition method varying CH4 concentration from 2.5 to 10% in the feeding gases. Thermal conductivity was measured on these free standing films by the steady state method from 80 K to 400K. They showed higher thermal conductivity as the film deposited with lower methane concentration. One exception, 7.79% methane concentration deposited film, was observed to be the highest thermal conductivity. Phonon scattering processes were considered to analyze the thermal conductivity with the full Callaway model. The grain size and the concentration of the extended and the point defects were used as the fitting parameters. Microstructure of diamond films was investigated with the scanning electron microscopy and Raman spectroscopy.

  • PDF