• Title/Summary/Keyword: nano-grain

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Characterization of Nano-Grained ZnO Piezoelectric Thin Films Deposited under Various Sputtering Conditions

  • Zhang, Ruirui;Lee, Eunju;Yoon, Giwan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2009.10a
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    • pp.428-430
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    • 2009
  • C-axis-oriented ZnO thin films were successfully deposited on p-Si (100) in an RF magnetron sputtering system. Deposition conditions such as deposition power, working pressure, and oxygen gas ratio were varied. Crystalline structures of the deposited ZnO films were investigated by a scanning electron microscope (SEM) technique. Results show that the deposition parameters can have a strong impact on the preferred orientations and grain sizes of the deposited ZnO films.

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Bandgap Alteration of Transparent Zinc Oxide Thin Film with Mg Dopant

  • Salina, M.;Ahmad, R.;Suriani, A.B.;Rusop, M.
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.2
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    • pp.64-68
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    • 2012
  • We have successfully demonstrated a bandgap alteration of transparent zinc oxide (ZnO) thin film with Mg dopant by using sol-gel spin coating technique. By increasing the dopant from 0 to 30 atomic percent (at.%), a decrement value in the cutoff is observed, where the absorption edge shifts continuously to the shorter wavelength side, towards 300 nm. This resulted in a significant bandgap increment from 3.28 to 3.57 eV. However, the transmittance of the thin film at 350-800 nm gradually downgraded, from 93 to 80 % which is most probably due to the grain size that becomes bigger, and it also affected the electrical properties. The decrement from 45 to 0.05 mA at +10 V was observed in the I-V characteristics, concluding the significant relationship; where higher optical bandgap materials will exhibit lower conductivity. These findings may be useful in optoelectronics devices.

Effect of Sintering Temperature on the Grain Size and Mechanical Properties of Al2O3-SiC Nanocomposites

  • Moradkhani, Alireza;Baharvandi, Hamidreza;Naserifar, Ali
    • Journal of the Korean Ceramic Society
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    • v.56 no.3
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    • pp.256-268
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    • 2019
  • In this research, some mechanical properties of Al2O3-based composites containing nanoSiC and nanoMgO additives, including elasticity modulus, hardness, and fracture toughness, have been evaluated. Micron-sized Al2O3 powders containing 0.08 wt.% nanoMgO particles have been mixed with different volume fractions of nanoSiC particles (2.5 to 15 vol.%). Untreated samples have been sintered by using hot-press technique at temperatures of 1600 to 1750℃. The results show significant increases in the mechanical characteristics with increases in the sintering temperature and amount of nanoSiC particles, with the result that the elasticity modulus, hardness, and fracture toughness were obtained as 426 GPa, 21 GPa, and 4.5 MPa.m1/2, respectively.

Electrical Properties of MIM and MIS Structure using Carbon Nitride Films

  • Lee, Hyo-Ung;Lee, Sung-Pil
    • Transactions on Electrical and Electronic Materials
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    • v.7 no.5
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    • pp.257-261
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    • 2006
  • Nano-structured carbon nitride $(CN_x)$ films were prepared by reactive RF magnetron sputtering with a DC bias at various deposition conditions, and the physical and electrical properties were investigated. FTIR spectrum indicated an ${alpha}C_3N_4$ peak in the films. The carbon nitride film deposited on Si substrate had a nano-structured surface morphology. The grain size was about 20 nm and the deposition rate was $1.7{\mu}m/hr$. When the $N_2/Ar$ ratio was 3/7, the level of nitrogen incorporation was 34.3 at%. The film had a low dielectric constant. The metal-insulator-semiconductor (MIS) capacitors that the carbon nitride was deposited as insulators, exhibited a typical C-V characteristics.

Thickness Dependence of the Electrical Properties in NiCr Thin Film Resistors Annealed in a Vacuum Ambient for π - type Attenuator Applications

  • Phuong Nguyen Mai;Lee Won-Jae;Yoon Soon-Gil
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.8
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    • pp.712-716
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    • 2006
  • NiCr thin films prepared on $SiO_2/Si$ substrates at room temperature by magnetron co-sputtering technique and then annealed in a vacuum ambient $(3{\times}10^{-6}\;Torr)\;at\;400^{\circ}C$. The grain size and crystallinity of the films increased with film thickness. The resistivity of the films slightly decreases as the film thickness increases, Temperature coefficient resistance (TCR) exhibits positive values irrespective of film thickness and TCR in the range of 50 to 400 nm thickness shows suitable values for the application of 10 dB in ${\pi}-type$ attenuators.

Fabrication of Micro Spur Gear in Nano Grained Al Alloy

  • Lee, Won-Sik;Jang, Jin-Man;Ko, Se-Hyun
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.778-779
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    • 2006
  • Manufacturing technologies of micro parts were studied in nano grained Al-1.5mass%Mg alloy. During compressive test at $300^{\circ}C$, the Al alloy showed stain softening phenomenon by grain boundary sliding regardless of strain rate. Micro spur gear with ten teeth (height of $200{\mu}m$ and pitch of $250{\mu}m$) was fabricated with sound shape by micro forging. During micro forging, increase of applied stress induced by friction between material and die surface was effectively compensated by decrease of stress by strain softening behavior and as a result, flow stress increased only about 50 MPa more than that in compressive test

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Fabrication and Properties of Nano-structured Ceramics

  • Ueno, Tomoyuki;Yoshimura, Masashi
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.321-322
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    • 2006
  • Nano-structured ceramics, which consist of structural elements with nanometer-size crystallites, are expected to show various unusual properties. We developed the novel nano-structured ceramics which consists of $Si_3N_4$ and TiN and a self-lubricant material. The ceramics was fabricated by powder metallurgy process using mechano-chemical grinding process and short-time sintering process. Each grain size of matrix and the self-lubricant particle was under about 50 nm and a few namometer. It showed high wear resistance and low friction coefficient by controlling of microstructure.

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Synthesis and Densification of Nanostructured $Al_2O_3-(Zro_2+3%Mol\;Y_2O_3)$ Bioceramics by High-Frequency Induction Heat Sintering

  • Kim, Sug-Won;Khalil, Khalil Abdel-razek
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.527-528
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    • 2006
  • Nanostructured Alumina - 20 vol% 3YSZ composites powder were synthesized by wet-milling technique. The starting materials were a mixture of Alumina micro-powder and 3YSZ nano-powders. Nano-crystalline grains were obtained after 24 h milling time. The nano-structured powder compacts were then processed to full density at different temperatures by high-frequency induction heat sintering (HFIHS). Effects of temperature on the mechanical and microstructure properties have been studied. $Al_2O_3-3YSZ$ composites with higher mechanical properties and small grain size were successfully developed at relatively low temperatures through this technique.

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