• Journal of the Korean Vacuum Society
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• v.11 no.3
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• pp.159-165
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• 2002

The physical properties of the TiN films deposited by ALD using $TiCl_4$and $NH_3$have been investigated. The TiN deposition rate is ~0.6 $\AA$ under an optimum deposition condition and the resistivity of the TiN films is 200~350 $\mu\Omega$cm . According to the XRD analysis results TiN films are crystallized in the ALD process window. AES analysis results show that the Cl impurity concentration in the TiN films is lower than 1 at% and that the atomic ratio of the TiN films is 1:1. Also it is found by SEM observation that the step coverage of the TiN films on which TiN films with trenches the aspect ratio of which is 10:1 is excellent.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.7
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• pp.73-81
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• 1992

We have investigated the thermal reaction property and the oxygen behavior of TiN/Ti/Si structure after different hear treatments using x-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy measurements. During the heat treatment in N$_2$ amibient, the considerable amount of oxygen atoms incorporates into TiN/Ti/Si Structures. It is found that oxygen atoms pile up at the top surface of TiN and TiN/Ti interface, forming a compound of TiO$_2$ above $600^{\circ}C$. Inside the TiN film, the oxygen content increases as the annealing temperature increases, mostly TiO and Ti$_2$O$_3$ rather than thermodynamically stable TiO$_2$. Above the annealing temperature of 55$0^{\circ}C$, the TiSi$_2$ formation has initiated. One thing to note is that a severe blistering is observed in the sample annealed at $600^{\circ}C$, due to (1) the difference of thermal expansion coefficient between TiN and Si` (2) the compressive stress induced by the volume reduction caused by the Ti-Silicide grain while elevating temperatures.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.90-96
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• 2000

The effects of the type and thickness of underlayers on the crystallographic texture and the sheet resistance of aluminum thin films were studied. Sputtered Ti and Ti/TiN were examined as the underlayer of the aluminum films. The texture and the sheet resistance of the metal thin film stacks were investigated at various thicknesses of Ti or TiN, and the sheet resistance was measured after annealing at $400^{\circ}C$ in an nitrogen ambient. For the Ti underlayer, the minimum thickness to obtain excellent texture of aluminum <111> was 10nm, and the sheet resistance of the metal stack was greatly increased after annealing due to the interdiffusion and reaction of Al and Ti. TiN between Ti and Al could suppress the Al-Ti reaction, while it deteriorated the texture of the aluminum film. For the Ti/TiN underlayer, the minimum Ti thickness to obtain excellent texture of aluminum <111> was 20nm, and the minimum thickness of TiN to function as a diffusion barrier between Ti and Al was 20nm.

• Journal of Powder Materials
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• v.9 no.6
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• pp.455-462
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• 2002

The microstructures and properties of TiC dispersed nickel-base alloy were studied in this work. The alloy prepared by powder metallurgical processing was solution treated, 1st-aged at $880^{\circ}C$ for 16 hours, and then 2nd-aged at $760^{\circ}C$ for 4 hours. Microstucture of sintered specimen showed that TiC particles are uniformly dispersed in Ni base alloy. In the specimen aged at $880^{\circ}C$ for 8 hours, the fine $\gammaNi_3$(Al,Ti) precipitates with round shape are observed and the very fine $\gammaNi_3$(Al,Ti) particles with round shape are precipitated in the specimen aged at $760^{\circ}C$ for 4 hours. The presence of ${\gamma}$precipitates in TiC/Ni base alloy increased the hardness and wear resistance of the specimen. The hardness and wear resistance of the Ni-base with TiC are higher than those of conventional Ni-base superalloy X-750 because of dispersion strengthening of TiC particles. The hardness, transverse rupture strength and resistance of the specimen 2nd-aged at $760^{\circ}C$ for 4 hours are higher than those of 1st-aged specimen due to ultrafine $\gammaNi_3$(Al,Ti) precipitates.

• Journal of Powder Materials
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• v.23 no.4
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• pp.282-286
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• 2016

A sintered body of $TiB_2$-reinforced iron matrix composite ($Fe-TiB_2$) is fabricated by pressureless-sintering of a mixture of titanium hydride ($TiH_2$) and iron boride (FeB) powders. The powder mixture is prepared in a planetary ball-mill at 700 rpm for 3 h and then pressurelessly sintered at 1300, 1350 and $1400^{\circ}C$ for 0-2 h. The optimal sintering temperature for high densities (above 95% relative density) is between 1350 and $1400^{\circ}C$, where the holding time can be varied from 0.25 to 2 h. A maximum relative density of 96.0% is obtained from the ($FeB+TiH_2$) powder compacts sintered at $1400^{\circ}C$ for 2 h. Sintered compacts have two main phases of Fe and $TiB_2$ along with traces of TiB, which seems to be formed through the reaction of TiB2 formed at lower temperatures during the heating stage with the excess Ti that is intentionally added to complete the reaction for $TiB_2$ formation. Nearly fully densified sintered compacts show a homogeneous microstructure composed of fine $TiB_2$ particulates with submicron sizes and an Fe-matrix. A maximum hardness of 71.2 HRC is obtained from the specimen sintered at $1400^{\circ}C$ for 0.5 h, which is nearly equivalent to the HRC of conventional WC-Co hardmetals containing 20 wt% Co.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.286-287
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• 2006

Barium titanate ($BaTiO_3$) glycolate particles were synthesized at temperature as low as $100^{\circ}C$ through glycothermal reaction by using $Ba(OH)_2{\cdot}8H_2O$ and amorphous titanium hydrous gel as precursors and ethylene glycol as solvent. The particle size and morphology of $BaTiO_3$ glycolate powders can be controlled by varying the reaction conditions such as the reaction temperature and Ba:Ti molar ratio of starting precursors. After glycothermal treatment at $220^{\circ}C$ for 24 h in 1.25:1(Ba:Ti), the average particle size of the $BaTiO_3$ glycolate powder was about 200-400 nm and low agglomeration. $BaTiO_3$ powders were formed by heat-treating the glycolate powder in air at $500-1000^{\circ}C$. As a result, the size of $BaTiO_3$ crystallites changed from around 50-300 nm. It is also demonstrated that the size and shape of $BaTiO_3$ particles investigated as a function of calcination temperature. The $BaTiO_3$ particles obtained from optimum synthesis condition were pressed, sintered and measured for the dielectric property. The $BaTiO_3$ ceramics sintered at $1250^{\circ}C$ for 2 h had 98 % of theoretical density. The ceramics have an average grain size of about $1\;{\mu}m$ and displays the high dielectric constant (~3100) and low dielectric loss (<0.1) at room temperature.

• Korean Journal of Materials Research
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• v.19 no.2
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• pp.55-60
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• 2009

In this study, Ti powder was fabricated from Ti scrap by a hydrogenation-dehydrogenation (HDH) method. The Ti powders were compacted by Spark plasma sintering (SPS) and the microstructure and mechanical properties of the powders were investigated. A hydrogenation reaction of Ti scrap occurred at temperatures near $450^{\circ}C$ with a sudden increase in the reaction temperature and a decrease in the pressure of the hydrogen gas as measured in a furnace during the hydrogenation process. In addition, a dehydrogenation process was carried out at $750^{\circ}C$ for 2hrs in a vacuum of $10^{-4}torr$. The Ti powder sizes obtained by hydrogenation-dehydrogenation and mechanical milling processes were in the range of $1{\sim}90{\mu}m$ and $1{\sim}100{\mu}m$, respectively. To fabricate Ti compacts, Ti powders were sintered under an applied uniaxial punch pressure of 40 MPa at in a range of $900{\sim}1200^{\circ}C$ for 5 min. The relative density of a SPSed compact was 99.6% at $1100^{\circ}C$, and the tensile strength decreased with an increase in the sintering temperature. However, the hardness increased as the sintering temperature increased.

• Korean Journal of Materials Research
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• v.24 no.4
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• pp.207-213
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• 2014

Flexible $BaTiO_3$ films as dielectric materials for high energy density capacitors were deposited on polyethylene terephthalate (PET) substrates by r.f. magnetron sputtering. The growth behavior, microstructure and electrical properties of the flexible $BaTiO_3$ films were dependent on the sputtering pressure during sputtering. The RMS roughness and crystallite size of the $BaTiO_3$ increased with increasing sputtering pressure. All $BaTiO_3$ films had an amorphous structure, regardless of the sputtering pressures, due to the low PET substrate temperature. The composition of films showed an atomic ratio (Ba:Ti:O) of 0.9:1.1:3. The electrical properties of the $BaTiO_3$ films were affected by the microstructure and roughness. The $BaTiO_3$ films prepared at 100 mTorr exhibited a dielectric constant of ~80 at 1 kHz and a leakage current of $10^{-8}A$ at 400 kV/cm. Also, films showed polarization of $8{\mu}C/cm^2$ at 100 kV/cm and remnant polarization ($P_r$) of $2{\mu}C/cm^2$. This suggests that sputter deposited flexible $BaTiO_3$ films are a promising dielectric that can be used in high energy density capacitors owing to their high dielectric constant, low leakage current and stable preparation by sputtering.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.131-132
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• 2015

$Ti_{0.26}Al_{0.16}Si_{0.01}N_{0.57}$ (at%) coatings were synthesized on stainless steel 304 by using arc ion plating systems (AIPS). Targets employed for the deposition were Ti, AlSi(67:33at%) and AlSi(82:18at%). The thickness of TiAlSiN coatings is $4{\mu}m$. The oxidation characteristics of the deposited coatings were studied by thermogravimetric analysis (TGA) in air between 800 and $900^{\circ}C$ for 75 hr. The oxide scale formed on the TiAlSiN coatings consisted of $rutile-TiO_2$ layer and ${\alpha}-Al_2O_3$. At $800^{\circ}C$, the coatings oxidized relatively slowly, and the scales were thin and adherent. When oxidized above $900^{\circ}C$, $TiO_2$ grew fast over the mixed oxide layer, and the oxide scale formed on TiAlSiN coatings was prone to spallation. Microstructural changes of the TiAlSiN coatings that occurred during high temperature oxidation were investigated by EPMA, XRD, SEM and TEM.

• Metals and materials international
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• v.24 no.6
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• pp.1386-1393
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• 2018

The solubility of $TiO_2$ in $NaF-CaF_2-BaF_2$ ternary eutectic melts was investigated at the temperature range of $1025-1150^{\circ}C$. The least-squares equation was obtained from the relationship between the reciprocal temperature and the natural logarithm of the titanium concentration in the melts saturated with $TiO_2$. The corresponding partial molar enthalpy of dissolution of $TiO_2$ was found to be 188 kJ/mol. The titanium saturation concentration was 3.73 wt% at $1100^{\circ}C$. From the titanium concentration change with the added amount of $TiO_2$ at different holding time after a final stirring, it was found that not only complete dissolution of $TiO_2$ but also enough sedimentation of excessive $TiO_2$ should be guaranteed to obtain more reliable solubility data. The holding time of 10 h was found to be enough for the excessive $TiO_2$ particles to settle down in our experimental conditions. It is noteworthy that in case of adding $TiO_2$ in excess of its solubility, the $Ba_{1.12}(Ti_8O_{16})$ phase was observed at the lower and bottom of the solidified salt ingots.