• Macromolecular Research
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• v.15 no.3
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• pp.244-255
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• 2007

Nucleation is the most sensitive stage in the preparation of highly cross-linked, monodisperse microspheres by dispersion polymerization, since the addition of a small amount of cross-linker results in particle deformation and coagulation. To overcome these problems, $5\;{\mu}m$ poly(methyl methacrylate) seed particles prepared by dispersion polymerization were used in the preparation of mono disperse, cross-linked PMMA particles containing up to 7 wt% divinylbenzene by seeded batch dispersion polymerization. Spherical particles with a narrow size distribution containing up to 8 wt% of EGDMA were prepared by seeded multi-batch dispersion polymerization processes. These particles were identified by scanning electron microscopy and DSC.

• Korean Journal of Crystallography
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• v.8 no.2
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• pp.75-80
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• 1997

A perovskite relaxor ferroelectrics PMN is used as an important material to investigate the diffusive phase transition phenomena. In this study PMN single crystals were grown and the microstructure were observed. For the growth of PMN single crystals, the spontaneous nucleation technique and the TSSG technique were used. 2-5mm single crystals were grown from PbO self flux and it was observed that only PMN crystals were grown when excess MgO was added over 100% as flux. Single crystals with well developed (001) faces were obtained from PbO-B2O3 flux. single crystals larger than 1 cm were grown from PbO-B2O3 flux by TXXG technique. For higher quality crystals, optimization of the variables such as the rotation speed of seed crystal, the orientation of seed crystal, and cooling rate is needed. With grown crystals, it was confirmed by TEM diffraction pattern of thin plate crystal that the 1:1 ordering of Mg2+ and Nb5+ with small volume exists.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.5
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• pp.247-252
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• 2002

$(Pb_{1-x}La_x)TiO_3$ (x = 0.1) thin films were prepared on ITO-coated glass substrates by metal organic chemical vapor deposition using ultrasonic spraying. Effects of the post-annealing and the seeding layer on crystallization, microstructures and electrical properties of thin films were investigated. Dielectric constants of films increased due to the modification of crystallization and the changing of a surface morphology by applying the post-annealing. In addition, as the application of PT seed- ing layer offered nucleation sites to PLT thin films, electrical properties of films were enhanced by the increase of crys-tallinity and grain size. The dielectric constant of the films post-heated for 60 min and with a seeding layer was 213 at 1 kHz.

• Electrical & Electronic Materials
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• v.28 no.2
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• pp.25-33
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• 2015

Ruthenium (Ru) thin films were grown on thermally-grown $SiO_2$ substrates by atomic layer deposition (ALD) using a sequential supply of four kinds of novel zero-valent Ru precursors, isopropyl-methylbenzene-cyclohexadiene Ru(0) (IMBCHDRu, $C_{16}H_{22}Ru$), ethylbenzen-cyclohexadiene Ru(0) (EBCHDRu, $C_{14}H_{18}Ru$), ethylbenzen-ethyl-cyclohexadiene Ru(0) (EBECHDRu, $C_{16}H_{22}Ru$), and (ethylbenzene)(1,3-butadiene)Ru(0) (EBBDRu, $C_{12}H_{16}Ru$) and molecular oxygen (O2) as a reactant at substrate temperatures ranging from 140 to $350^{\circ}C$. It was shown that little incubation cycles were observed for ALD-Ru processes using these new novel zero-valent Ru precursors, indicating of the improved nucleation as compared to the use of typical higher-valent Ru precursors such as cyclopentadienyl-based Ru (II) or ${\beta}$-diketonate Ru (III) metallorganic precursors. It was also shown that Ru nuclei were formed after very short cycles (only 3 ALD cycles) and the maximum nuclei densities were almost 2 order of magnitude higher than that obtained using higher-valent Ru precursors. The step coverage of ALD-Ru was excellent, around 100% at on a hole-type contact with an ultra-high aspect ratio (~32) and ultra-small trench with an aspect ratio of ~ 4.5 (top-opening diameter: ~ 25 nm). The developed ALD-Ru film was successfully used as a seed layer for Cu electroplating.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.242-245
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• 2009

AlN crystals were grown by a sublimation process without seed crystals and the growth morphology of them was characterized. The grown AlN crystals were a polycrystalline phase, which had a diameter of $60\sim200\;{\mu}m$ and were grown with a growth rate of $0.2\sim0.5\;{\mu}n/hr$. It was observed that the as-grown crystals had a hexagonal crystal structure and revealed that these crystals were grown with a morphology of columnar morphology in the initial stage of the growth before they were enlarged in a way of a lateral growth behavior in the final stage. On the surface, a lot of pinholes were observed on the surface of crystals grown. The evolution of a growth morphology was characterized by optical and scanning electron microscopic observation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.8
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• pp.451-454
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• 2000

We have grown vertically aligned carbon nanotubes in a large area of Co-Ni codeposited Si substrates by the thermal CVD usign $C_2H_2$ gas. Since the discovery of carbon nanotubes, growth of carbon nanotubes has been achieved by several methods such as laser vaporization, arc discharge, and pyrolysis. In particular, growth of vertically aligned nanotubes is important to flat panel display applications. Recently, vertically aligned carbon nanotubes have been grown on glass by PECVD. Aligned carbon nanotubes can be also grown on mesoporous silica and Fe patterned porous silicon using CVD. In this paper, we demonstrate that carbon nanotubes can be vertically aligned on catalyzed Si substrate when the domain density of catalytic particles reaches a certain value. We suggest that steric hindrance between nanotubes at an initial stage of the growth forces nanotubes to align vertically and each nonotubes are grown in bundle.

• Journal of the Korean Ceramic Society
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• v.35 no.8
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• pp.827-835
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• 1998

Blanket Copper films were chemically vapor deposited on six kinds for substrates for scrutinizing the change of characteristics induced by the difference of substrates and seeding layers. Both TiN/Si and {{{{ { SiO}_{2 } }}/Si wafers were used as-recevied and with the Cu-seeding layers of 40${\AA}$ and 160${\AA}$ which were produced by sputtering The CVD processes were exectued at the deposition temperatures between 130$^{\circ}C$ and 260$^{\circ}C$ us-ing (hfc)Cu(VTMS) as a precursor. The deposition rate of 40$^{\circ}C$ Cu-seeded substrates was higher than that of other substrates and especially in seeded {{{{ { SiO}_{2 } }}/Si substrate because of the incubation period reducing in-duced by seeding layer at the same deposition time and temperature. The resistivity of 160${\AA}$ Cu seeded substrate was lower then that of 40 ${\AA}$ because the nucleation and growth behavior in Cu-island is different from the behavior in {{{{ { SiO}_{2 } }} substrate due to the dielectricity of {{{{ { SiO}_{2 } }}.

• Transactions on Electrical and Electronic Materials
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• v.12 no.5
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• pp.193-196
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• 2011

Lead zirconate titanate (PZT)/ bismuth ferrite (BFO) multilayer thin films have been fabricated by the spin-coating method on Pt(200 nm)/Ti(10 nm)/$SiO_2$(100 nm)/p-Si(100) substrates using $BiFeO_3$ and $Pb(Zr_{0.52}Ti_{0.48})O_3$ metal alkoxide solutions. The PZT/BFO multilayer thin films show a uniform and void-free grain structure, and the grain size is smaller than that of PZT single films. The reason for this is assumed to be that the lower BFO layers play an important role as a nucleation site or seed layer for the formation of homogeneous and uniform upper PZT layers. The dielectric constant and dielectric losses decreased with increasing number of coatings, and the six-layer PZT/BFO thin film has good properties of 162 (dielectric constant) and 0.017 (dielectric losses) at 1 kHz. The remnant polarization and coercive field of three-layer PZT/BFO thin films were 13.86 ${\mu}C/cm^2$ and 37 kV/cm respectively.

• Journal of the Korea Concrete Institute
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• v.27 no.3
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• pp.265-272
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• 2015

In this study, a method to reduce temperature rise due to hydration in mass concrete is investigated. It is to use retarder (glucose) for reducing heat of hydration and to use calcium silicate hydrate (C-S-H) for compensating the retardation effect due to its role as a nucleation seed. For this purpose, the temperature rise of cement paste due to hydration was measured and the effect of using both C-S-H and glucose on setting and 28-day compressive strength of mortar specimens was investigated. According to the experimental results, using C-S-H and glucose caused the reduction in the maximum temperature but accelerated the time to reach the maximum temperature compared to that of retarded cement paste using glucose. In addition, using C-S-H and glucose did not show significant effect on 28-day compressive strength of mortar specimens, indicating that the method shown in this study can be a successful alternative to control maximum temperature rise in mass concrete.

• Journal of Powder Materials
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• v.29 no.6
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• pp.511-516
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• 2022

Electroless plating is widely utilized in engineering for the metallization of insulator substrates, including polymers, glass, and ceramics, without the need for the application of external potential. Homogeneous nucleation of metals requires the presence of Sn-Pd catalysts, which significantly reduce the activation energy of deposition. Therefore, rinsing conducted during Sn sensitization and Pd activation is a key variable for the formation of a uniform seed layer without the lack or excess of catalysts. Herein, we report the optimized rinsing process for the functionalization of Sn-Pd catalysts, which enables the uniform FeCo metallization of the glass fibers. Rinsing enables good deposition of the FeCo alloy because of the removal of excess catalysts from the glass fiber. Concurrently, excessive rinsing results in a complete removal of the Sn-Pd nucleus. Collectively, the comprehensive study of the proposed nanomaterial preparation and surface science show that the metallization of insulators is a promising technology for electronics, solar cells, catalysts, and mechanical parts.