• 한국재료학회지
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• 제29권11호
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• pp.684-689
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• 2019

Single crystals, which have complexed composition, are fabricated by solid state grain growth. However, it is hard to achieve stable properties in a single crystal due to trapped pores. Aerosol deposition (AD) is suitable for fabrication of single crystals with stable properties because this process can make a high density coating layer. Because of their unique features (nano sized grains, stress inner site), it is hard to fabricate single crystals, and so studies of grain growth behavior of AD film are essential. In this study, a $BaTiO_3$ coating layer with ${\sim}9{\mu}m$ thickness is fabricated using an aerosol deposition method on (100) and (110) cut $SrTiO_3$ single crystal substrates, which are adopted as seeds for grain growth. Each specimen is heat-treated at various conditions (900, 1,100, and $1,300^{\circ}C$ for 5 h). $BaTiO_3$ layer shows different growth behavior and X-ray diffraction depending on cutting direction of $SrTiO_3$ seed. Rectangular pillars at $SrTiO_3$ (100) and laminating thin plates at $SrTiO_3$ (110), respectively, are observed.

• 한국전기전자재료학회논문지
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• 제25권8호
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• pp.584-592
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• 2012

Room temperature powder spray in vacuum process, so called Aerosol deposition (AD) is a room temperature (RT) process to fabricate thick and dense ceramic films, based on collision of solid ceramic particles. This technique can provide crack-free dense thin and thick films with thicknesses ranging from sub micrometer to several hundred micrometers with very fast deposition rates at RT. In addition, this technique is using solid particles to form the ceramic films at RT, thus there is few limitation of the substrate and easy to control the compositions of the films. In this article, we review the progress made in synthesis of piezoelectric thin/thick films, multi-layer structures, NTC thermistor thin/thick films, oxide electrode thin films for actuators or sensor applications by AD at Korea Institute of Materials Science (KIMS) during the last 4 years.

• 한국세라믹학회지
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• 제45권7호
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• pp.411-417
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• 2008

Aerosol Deposition Method (ADM) is a novel technique to grow ceramic thick films with high density and nano-crystal structure at room temperature. $^{1,2)}$ For these unique advantages of ADM, it would be applied to the fabrication process of 3-D integration ceramic modules effectively. However, it is critical to control the properties of starting powders, because a film formation through ADM is achieved by impaction and consolidation of starting powders on the substrates. We fabricated alumina thick films by ADM for the application to integral substrates for RF modules. When the as-received alumina powders were used as a starting material without any treatments, it was observed that the dielectric properties of as-deposited alumina films, such as relative permittivity and loss tangent, showed high dependency on the frequency. In this study, some techniques of powder pre-treatments to improve the dielectric properties of alumina thick films will be shown and the effects of starting powders on the properties of AD films will be discussed.

• 한국전기전자재료학회논문지
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• 제35권4호
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• pp.412-417
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• 2022

Capacitive-type humidity sensors with a high sensitivity and fast response/recovery times have attracted a great attention in non-contact respiration biological signal monitoring applications. However, complicated fabrication processes involving high-temperature heat treatment for the hygroscopic film is essential in the conventional ceramic-based humidity sensors. In this study, a non-toxic ceramic/metal halide (BaTiO₃(BT)/NaCl) humidity sensor was prepared at room temperature using a solvent-free aerosol deposition process (AD) without any additional process. Currently prepared BT/NaCl humidity sensor shows an excellent sensitivity (245 pF/RH%) and superior response/recovery times (3s/4s) due to the NaCl ionization effect resulting in an immense interfacial polarization. Furthermore, the non-contact respiration signal variation using the BT/NaCl sensor was determined to be over 700% by maintaining the distance of 20 cm between the individual and the sensor. Through the AD-fabricated sensor in this study, we expect to develop a non-contact biological signal monitoring system that can be applied to various fields such as respiratory disease detection and management, infant respiratory signal observation, and touchless skin moisture sensing button.

• 한국재료학회지
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• 제31권10호
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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.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.41.1-41.1
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• 2009

Aerosol Deposition (AD) is anovel way to fabricate bioactive ceramic coatings in biomedical implants and prostheses applications. In the present work, silicon-substituted hydroxyapatite (HA) coatings on commercially pure titanium were prepared by aerosol deposition using Si-HA powders. The incorporation of silicon in the HA lattice is known to improve the bioactivity of the HA, makingsilicon-substitute HA an attractive alternative to pure HA in biomedical applications. Si-HA powders with the chemical formula $Ca_{10}(PO_4)_6-x(SiO_4)x(OH)_2-x$, having silicon contents up to x=0.5 (1.4 wt%), were synthesized by solid-state reaction of $Ca_2P_2O_7$, $CaCO_3$, and $SiO_2$. The Si-HA powders were characterized by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), and Fourier transform infrared spectroscopy(FT-IR). The corresponding coatings were also analyzed by XRD, scanning electron microscopy (SEM), and electron probe microanalyzer (EPMA). The results revealed that a single-phase Si-HA was obtained without any secondary phases such as $\alpha$- or $\beta$-tricalcium phosphate (TCP) for both the powders and the coatings.The Si-HA coating was about $5\;{\mu}m$ thick, had a densemicrostructure with no cracks or pores. In addition, the proliferation and alkaline phosphatase (ALP) activity of MC3T3-E1 preosteoblast cells grown on the Si-HA coatings were significantly higher than those on the bare Ti and pure HA coating. These results revealed the stimulatory effects induced by siliconsubstitution on the cellular response to the HA coating.

• 한국대기환경학회지
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• 제21권1호
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• pp.119-129
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• 2005

The ambient TSP data measured at Seoul, Incheon. Taean, Daegu, Busan in Korea were used to explain the chemical composition and general features of Asian Dust (AD) observed in Korea. 9 episodes out of 19 were sampled from 2000 through May 2002, and measurements were conducted covering ionic and metal components with mass concentration. The results showed that daily averaged mass concentration (TSP) during the AD episodes was 458 $\mu\textrm{g}$/㎥, and ionic and metal concentrations were 27.93 $\mu\textrm{g}$/㎥ and 71.7 $\mu\textrm{g}$/㎥, respectively, accounting for 6.1 % and 15.5% of the total aerosol mass. TSP concentrations during episodes were varied from 120 to 1742 $\mu\textrm{g}$/㎥ according to the impact of Asian Dusts and had a tendency of showing higher values at sites in the west side of Korea, which can be explained by the effect of diffusion and deposition. In this study, ionic components like Ca (NO$_3$)$_2$, CaSO$_4$, NaNO$_3$, Na$_2$SO$_4$ were prominent types in secondary aerosol during AD periods and also indicated that V, Co as well as soil elements such as Ca, Fe, Mg, Mn, K correlated well with Al, while Cu, Cd, Pb, Zn didn't agree well with it. In addition, enrichment factors (EFs) for each metal component were obtained to provide simple information about source contribution of Asian Dust, and the results were compared with those from other AD studies. In this study, the results showed that aerosol properties in Korea during the Asian Dust were considerably different from those of general atmospheric condition and specially varied from case to case rather than site to site, which implies that there are certain variations in the soil of source region, pathways of air mass, and meteorological condition. For the enhanced study, those factors should be combined with the features of Asian Dust resolved from this study.

• 한국세라믹학회지
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• 제45권12호
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• pp.839-844
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• 2008

$TiO_2$ is an environment-friendly semiconducting material, and it has photocatalytic and hydrophilic effect. There are a lot of reports on the photocatalytic characteristics of $TiO_2$, such as organic pollutants resolving, anti-bacterial, and self-purification material. In this paper, $TiO_2$ micron-sized powders were deposited on the glass by room temperature powder spray in vacuum process, so called aerosol deposition (AD), and nano-grained $TiO_2$ photocatalytic thin films were fabricated. The thickness of the films were controlled by changing the number of deposition cycle. Morphologies and characteristics of the AD-$TiO_2$ thin films were examined by SEM, TEM, XRD, and UV-Visible Spectrophotometer. As the thickness of $TiO_2$ films increased, surface roughness increased. By this increment, the reaction area between film and pollutant was enlarged, resulting in better photocatalytic property.