• 한국세라믹학회지
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• 제28권11호
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• pp.926-934
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• 1991

The effect of aggregates on the forming and sintering behaviors of BaTiO3 was studied. Aggregates and deaggregates of fine crystallite were obtained by thermal decomposition of oxalate coprecipitates and subsequently crushing them with a press, respectively. Large voids formed by packing of aggregates were not easily eliminated despite the successive destruction of aggregates with increasing forming pressure. As a result, compacts of aggregates showed inhomogeneity with larger mid-pore size and broader pore size distribution with respect to those of deaggregates. This inhomogeneity caused differential shrinkage and consequental internal stress, which retarded densification. The differential sintering increased the size of mid-pores in the initial stage, and formed duplex structure composed of dense region with abnormally grown grains and porous region with fine grains. The driving force of this abnormal grain growth shown in the specimens of aggregates was attributed to the minimization of the elastic strain energy due to internal stress.

• 한국세라믹학회지
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• 제46권6호
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• pp.545-547
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• 2009

An immiscible Si/Sn (=7/3 by volume) powder mixture was subjected to simple grinding and subsequent leaching process to give Sn nanopowder reinforced or dispersed in Si powder. Crystallite and their agglomerates of Si were ca. 15 nm and 100 nm, respectively. Sn remained at 4.5 vol% in Si powder after aqueous HCl leaching, dispersively occluded in Si matrix as confirmed by ICP analysis and cross sectional TEM observation.

• 한국세라믹학회지
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• 제47권4호
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• pp.338-342
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• 2010

Co, $Fe_3O_4$ and Co/$Fe_3O_4$ nanoparticles were synthesized by a polyol process in order to develop their new applications and improve chemical, magnetic properties. The synthesis involved a polyol process using Fe, Co acetylacetonate as precursors and 1-2 hexadecanediol as the polyol. The synthesized $Fe_3O_4$ and Co/$Fe_3O_4$ nanocomposite particles were monodispersed and self arrayed ranging in size of 8~10 and 10~25 nm, respectively. The Co nanoparticle has a crystallite size of 10~40 nm. The synthesized nanoparticles were characterized by their structural, morphological, compositional and magnetic properties using TEM-EDS, XRD, and PPMS techniques.

• JSTS:Journal of Semiconductor Technology and Science
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• 제9권2호
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• pp.117-123
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• 2009

$Pb_{x}Cd_{1-x}S$ films are prepared in the composition range of 0.05${\leq}x{\leq}$0.25, using a chemical bath deposition growth technique under optimum conditions amide at realizing good photo response. The x-ray diffraction results show that the films are of PbS-CdS composite with individual CdS and PbS planes. The films exhibit two direct band gaps, 2.4 eV attributed to CdS, while the other varies continuously from 2.4 eV to 1.3 eV. The films surface morphology is smooth with crystallite, whose grain size increases with increasing mole fraction (x). The decrease in band gap with increase in lead concentration suggests inter-metallic compound of PbS (Eg=0.41 eV) with CdS (Eg=2.4 eV)

• Transactions on Electrical and Electronic Materials
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• 제18권6호
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• pp.316-319
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• 2017

A new approach to improving the electrical characteristics and optical response of a polysilicon-based metal-semiconductor-metal (MSM) photodetector is proposed. To understand the cause of current restriction in the MSM photodetector, modified trap mechanisms are suggested, which include interfacial electron traps at the metal/polysilicon interface and silicon dangling bonds between silicon crystallite grains. Those traps were passivated using hydrogen ion implantation with subsequent post-annealing. Photodetectors that were ion-implanted under optima conditions exhibited improved photoconductivity and reduced dark current instability, implying that the hydrogen bonds in the polysilicon influence the simultaneous decreases in the density of dangling bonds at grain boundaries and the trapped positive charges at the contact interface.

• 에너지공학
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• 제24권2호
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• pp.55-58
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• 2015

The mesoporous metal organic framework structure Fe-BTC was successfully synthesized by hydrothermal process with noticeable yield. The synthesis operation was conducted at intermediate temperature and for shortened operation time as compared to conventional procedures. This process approach with reduced operating temperature and shortened operation time may open an opportunity window towards process economy with reduction in energy consumption. A simple mathematical approach of diffraction indexing using X-ray diffraction patterns of synthesized powder was employed to confirm its crystalline nature and to investigate its high temperature stability. The crystallite size was calculated by using Debye-Scherrer equation.

• 한국분말재료학회지
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• 제7권1호
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• pp.19-26
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• 2000

Al-Cr-Zr metal powders were prepared by cryo-milling(-75$^{\circ}C$),ambi-milling(25$^{\circ}C$) and warm-milling(200$^{\circ}C$) to investige the effect of milling temperature. The morphogical changes and microstructural evolution of Al-6wt.%Cr-3wt.%Zr metal powder ball milling were investigated by SEM, OM and XRD. The cryo-milling at -75$^{\circ}C$ caused the more refinement of powder particle size than ambi-milling and warm-milling. The partic morpholgy of Al-Cr-Zr metal powders changed changes into spheroidal particles at 25$^{\circ}C$and spherical particles at 200$^{\circ}C$The spherical particles were formed by agglomertion and contiuous wrapping of the spheroidal particles. The calculated Al crystallite size in Al-Cr-Zr metal powders by the Scherer equation were refined rapidly for short milling time -75$^{\circ}C$compared with milling at 25$^{\circ}C$ and 200$^{\circ}C$.

• Journal of Magnetics
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• 제18권2호
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• pp.155-158
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• 2013

FeCoB films were being prepared on a Ru underlayer by using the oblique incidence of sputtered and back-scattered particles which have a high in-plane magnetic anisotropy field $H_k$ above 400 Oe. It is suitable to attain such deposition condition when facing targets sputtering system. The in-plane X-ray diffraction analysis clarified that there is anisotropic residual stress which is the origin of the high in-plane magnetic anisotropy. The directional crystalline alignment and inclination of crystallite growth were also observed. Such anisotropic crystalline structures may affect the anisotropic residual stress in the films. The B content of 5.6 at.% was appropriate to induce such anisotropic residual stress and $H_k$ of 410 Oe in this experiment. The film with B content of 6 at.% possessed large saturation magnetization of 22 kG and high $H_k$ of 500 Oe. The film exhibited high ferromagnetic resonance frequency of 9.2 GHz.

• 한국표면공학회지
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• 제35권4호
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• pp.211-217
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• 2002

Ti-Si-N films were deposited onto WC-Co substrate by a RF-PECVD technique. The deposition behaviors of Ti-Si-N films were investigated by varying the deposition temperature, RF power, and reaction gas ratio (Mx). Ti-Si-N films deposited at 500, 180W, and Mx 60% had a maximum hardness value of 38GPa. The microstructure of films with a maximum hardness was revealed to be a nanocomposite of TiN crystallites penetrated by amorphous silicon nitride phase by HRTEM analyses. The microstructure of maximum hardness with Si content (10 at.%) was revealed to be a nanocomposite of TiN crystallites penetrated by amorphous silicon nitride phase, but to have partly aligned structure of TiN and some inhomogeniety in distribution. and At above 10 at.% Si content, TiN crystallite became finer and more isotropic also thickness of amorphous silicon nitride phase increased at microstructure.

• 한국전기전자재료학회논문지
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• 제15권2호
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• pp.184-189
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• 2002

Carbon nitride films were grown on Si (100) substrate by a laser-electric discharge method with/without a magnetic field assistance. The magnetic field leads to vapor plume plasma expending upon the ambient arc discharge plasma area. Influence of the magnetic field has resulted in increased of a crystallite size int he films due to bombardment (heating) of Si substrates by energetic carbon and nitrogen species generated during cyclotron motion of electrons in the discharge zone. The surface morphology of the films with a deposition time of 2 hours was studied using a scanning electron microscopy (SEM). In order to determine the structural crystalline parameters, X-ray diffraction (XRD) was used to analysis the grown films.