• Korean Journal of Materials Research
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• v.31 no.10
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• pp.546-551
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• 2021

To improve ferroelectric properties of PZT, many studies have attempted to fabricate dense PZT films. The AD process has an advantage for forming dense ceramic films at room temperature without any additional heat treatment in low vacuum. Thick films coated by AD have a higher dielectric breakdown strength due to their higher density than those coated using conventional methods. To improve the breakdown strength, glass (SiO₂-Al₂O₃-Y₂O₃, SAY) is mixed with PZT powder at various volume ratios (PZT-xSAY, x = 0, 5, 10 vol%) and coating films are produced on silicon wafers by AD method. Depending on the ratio of PZT to glass, dielectric breakdown strength and energy storage efficiency characteristics change. Mechanical impact in the AD process makes the SAY glass more viscous and fills the film densely. Compared to pure PZT film, PZT-SAY film shows an 87.5 % increase in breakdown strength and a 35.3 % increase in energy storage efficiency.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1692-1696
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• 2018

Ferroelectric $BaTiO_3$/poly(vinylidene fluoride) (PVDF) nanocomposite films were successfully prepared by mixing $BaTiO_3$ nano-particles into PVDF solution dissolved in dimethylformamide under ultrasonification. The mixture was casted onto glass petri dish and then annealed at $100^{\circ}C$ for 12 h in vacuum dry oven. Crystal structure and surface morphology of the samples were analyzed by using an X-ray diffraction analysis and a field emission-scanning electron microscope, respectively. The relative dielectric permittivity and loss tangent were determined in the frequency range of 50 Hz to 1 MHz. For the $BaTiO_3/PVDF$ nanocomposites, the entire diffraction peaks match those indicated by standard $BaTiO_3$ perovskite structure. The FE-SEM image reveals the homogeneity of the $BaTiO_3$ nanopowder distribution and also predominant 0-3 connectivity. All results show that the dielectric properties of the nanocomposite films are desirable and the fabrication technique for preparing the $BaTiO_3/PVDF$ nanocomposites has a potential in the electronic applications.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.399-402
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• 2005

We have studied the Pixel Isolated Phase Separated Composite Organic Film (PI-PSCOF). The PI-PSCOF can be made by the anisotropic phase separation between Ferroelectric Liquid Crystals and Pre-polymer materials by irradiating the UV with optimizing its intensity and time. In the technology, the FLC molecules are isolated in pixels where FLCs are surrounded by the inter-pixel vertical polymer walls and the horizontal polymer films on the upper substrate. The good merits of this technology are fast response time, and good mechanical and thermal stability against external high pressure and temperature. We will compare the results obtained from FLC, PSCOF, and PI-PSCOF modes by using the electro-optic measurement and x-ray scattering, and mechanical method. We believe that the PI-PSCOF technology can be a best candidate for future Flexible Display Applications.

• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1544-1553
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• 2005

In this article, a micro cantilever array actuated by PZT films is designed and fabricated for micro fluidic systems. The design features for maximizing tip deflections and minimizing fluid leakage are described. The governing equation of the composite PZT cantilever is derived and the actuating behavior predicted. The calculated value of the tip deflection was 15 ${\mu}m$ at 5 V. The fabrication process from SIMOX (Separation by oxygen ion implantation) wafer is presented in detail with the PZT film deposition process. The PZT films are characterized by investigating the ferroelectric properties, dielectric constant, and dielectric loss. Tip deflections of 12 ${\mu}m$ at 5 V are measured, which agreed well with the predicted value. The 18 ${\mu}l/s$ leakage rate of air was observed at a pressure difference of 1000 Pa. Micro cooler is introduced, and its possible application to micro compressor is discussed.

• Composites Research
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• v.28 no.5
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• pp.270-276
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• 2015

Polyvinylidene fluoride (PVDF)-based nanocomposites are fabricated by incorporation of boron nitride (BN) nanosheets with anisotropic orientation for a potential high thermal conducting ferroelectric materials. The PVDF is dissolved in dimethylformamide (DMF) and homogeneously mixed with exfoliated BN nanosheets, which is then cast into a polyimide film under application of high magnetic fields (0.45~10 T), where the direction of the filler alignment was controlled. The BN nanosheets are exfoliated by a mixed way of solvothermal method and ultrasonication prior to incorporation into the PVDF-based polymer suspension. X-ray diffraction, scanning electron microscope and thermal diffusivity are measured for the characterization of the polymer nanocomposites. Analysis shows that BN nanosheets are exfoliated into the fewer layers, whose basal planes are oriented either perpendicular or parallel to the composite surfaces without necessitating the surface modification induced by high magnetic fields. Moreover, the nanocomposites show a dramatic thermal diffusivity enhancement of 1056% by BN nanosheets with perpendicular orientation in comparison with the pristine PVDF at 10 vol % of BN, which relies on the degree of filler orientation. The mechanism for the magnetic field-induced orientation of BN and enhancement of thermal property of PVDF-based composites by the BN assembly are elucidated.