• Title/Summary/Keyword: Low-dimensional materials

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A Two-Dimensional Terrace-Like N-heterocyclic-Pb(II) Coordination Compound: Structure and Photoluminescence Property

  • Ma, Kui-Rong;Zhu, Yu-Lan;Zhang, Yu;Li, Rong-Qing;Cao, Li
    • Bulletin of the Korean Chemical Society
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    • v.32 no.3
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    • pp.894-898
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    • 2011
  • The first example of lead compound from $Pb(NO_3)_2$ and $H_3L$ N-heterocyclic ligand $(H_3L\;=\;(HO_2C)_2(C_3N_2)(C_3H_7)CH_2(C_6H_4)(C_6H_3)CO_2H)$, $[Pb_4(L')_4]{\cdot}5H_2O$ 1 (L' = OOC$(C_3H_7)(C_3N_2)CH_2(C_6H_4)(C_6H_3)COO)$, has been obtained under hydrothermal condition by decarboxylation, and characterized by elemental analysis, IR, TGDTA, and single-crystal X-ray diffraction. Compound 1 possesses a rare two-dimensional upper-lower offset terrace-like layer structure. In 1, crystallographic distinct Pb(II) ion adopts five-coordination geometry, and two lattice water molecules occupy the voids between 2-D layers. Results of solid state fluorescence measurement indicate that the emission band 458 nm may be assigned to $\pi^*-n$ and $\pi^*-\pi$ electronic transitions within the aromatic systems of the ligand L', however, the emission bands centred at 555 nm, 600 nm and 719 nm may be derived from phosphorescent emission ($\lambda_{excitation}$ = 390 nm).

DIMENSIONAL STABILITY OF ELASTOMERIC IMPRESSION MATERIALS USING HOLOGRAPHIC INTERFEROMETRY (Holographic Interferometry를 이용한 탄성 고무 인상재의 체적변화에 관한 연구)

  • Ha, Chee-Yang;Lee, Sung-Bok;Woo, Yi-Hyung
    • The Journal of Korean Academy of Prosthodontics
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    • v.34 no.3
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    • pp.574-592
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    • 1996
  • This study investigated the time-dependent dimensional changes of elastomeric impression materials using holographic interferometry. Six commercial impression materials, Permlastic(polysulfide), Xantopren VL (condensation silicone), low and medium viscosity of Exafine, Provil (addition silicone), and Impregum(polyether), were selected. Steel plate was used as custom tray, and each impression specimen was 20 mm in width, 15 mm in length and 3 mm in thickness. Each impression material was evaluated at 30 minutes, 1, 2, 4, 6, 8 and 12 hours after setting using real-time holography. The results were as follow : 1. Xantopren VL and Permlastic showed relatively severe and continuous dimensional changes after setting. Low viscosity of Exafine, Provil, Impregum showed relatively slight dimensional changes with function of time and medium viscosity of Exafine showed almost no dimensional change from 2 hours after setting to 6 hours. 2. On initial dimensional changes within 1 hour, the amount of change in low viscosity of Exafine was the least and Xantopren VL was the largest. 3. On dimensional changes at 4 hours after setting, the amount of change in medium viscosity of Exafine was the least and tile change of Xantopren VL was the largest. 4. In overall dimensional stability during 12 hours, medium viscosity of Exafine was the most stable and Xantopren VL and Permlastic were least stable.

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Review of Low-Dimensional Nanomaterials for Blue-Light Emission

  • Won Kook Choi
    • Journal of Sensor Science and Technology
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    • v.32 no.6
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    • pp.391-402
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    • 2023
  • Low-dimensional (zero-dimensional (0-dim), 2-dimensional (2-dim)) nanoparticles, such as chalcogenide compound semiconductors, III-V semiconductors, transition metal dichalcogenides (TMDs), II-VI semiconductors, nanocarbons, hybrid quantum dots (QDs), and perovskite QDs (PQDs), for which blue light emission has been observed, are reviewed. Current synthesis and device fabrication technologies as well as their prospective applications on next-generation quantum-dot-based light-emitting diodes are discussed.

Cu Electroplating and Low Alpha Solder Bumping on TSV for 3-D Packaging (3차원 실장을 위한 TSV의 Cu 전해도금 및 로우알파 솔더 범핑)

  • Jung, Do hyun;Kumar, Santosh;Jung, Jae pil
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.4
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    • pp.7-14
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    • 2015
  • Research and application of three dimensional packaging technology in electronics have been increasing according to the trend of high density, high capacity and light weight in electronics. In this paper, TSV fabrication and research trend in three dimensional packaging are reported. Low alpha solder bumping which can solve the soft error problem in electronics is also introduced. In detail, this paper includes fabrication of TSV, functional layers deposition, Cu filling in TSV by electroplating using PPR (periodic pulse reverse) and 3 step PPR processes, and low alpha solder bumping on TSV by solder ball. TSV and low alpha solder bumping technologies need more studies and improvements, and the drawbacks of three dimensional packaging can be solved gradually through continuous attentions and researches.

1차원 무기 반도체 신 물질 재료의 연구 개발 동향

  • Ryu, Hak-Gi
    • Ceramist
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    • v.21 no.2
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    • pp.29-37
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    • 2018
  • In order to overcome the problems of existing low-dimensional materials (carbon nanotubes, graphene, transition metal dichalcogenides, etc) researches on new 1D materials have been studied. In the case of $LiMo_3Se_3$ and $Mo_6S_{9-x}I_x$, continuous researches have been carried out for 3D bulk synthesis and atomic scale dispersion. Recently, quantum confinement effect of $LiMo_3Se_3$ and bio-stability of $Mo_6S_{9-x}I_x$ have been proven and various applications have started to be studied. In addition, device application results using new 1D materials such as $Sb_2Se_3$ (optoelectronic devices using the property of effectively reducing exciton decay due to no dangling bond) and $VS_4$ (electrochemical energy storage using the space between 1-D nanostructures) have been reported very importantly. Therefore, it can be claimed that it has reached a very important time to find and synthesize new 1D materials and to report various characteristics not existing.

Observation of saturation transfer characteristics in solution processed vertical organic field-effect transistors (VOFETs) with high leakage current

  • Sarjidan, M.A. Mohd;Shuhaimi, Ahmad;Majid, W.H. Abd.
    • Current Applied Physics
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    • v.18 no.11
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    • pp.1415-1421
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    • 2018
  • Unlike ordinary organic field-effect transistors (OFETs), saturation current is hardly to be found in vertical OFETs (VOFETs). Moreover, the fabrication process of patterned sourced for VOFETs is quite complex. In this current work, a simple solution processed VOFET with directly deposited intermediate silver source electrode has been demonstrated. The VOFET exhibits a high leakage current that induces an inversion polarity of its transistor behavior. Interestingly, a well-defined saturation current was observed in the linear scale of transfer characteristic. The VOFET operated with high-current density > $280mA/cm^2$ at $V_d=5V$. Overview potential of the fabricated device in display application is also presented. This preliminary work does open-up a new direction in VOFET fabrication and their application.