• Journal of the Korean institute of surface engineering
• /
• v.29 no.5
• /
• pp.330-337
• /
• 1996

A rf reactive sputter deposition technique was adopted to deposit ferroelectric lead zirconate titanate (PZT) thin films with high rate from a ZrTi alloy target combined with PbO pellets. Deposition characterisitics including the effects of PbO are ratio were discussed. A new deposition mode called the quasi-metallic mode was observed. Perovskite PZT films were prepared at a growth temperature as low as$ 450^{\circ}C$. However, because the target structure is unstable, weproposed a mixture target consisted of Zr, Ti and PbO. Fundamental experiments were investigated using the powder target. Perovskite PZT film could be obtained at $450^{\circ}C$ with better electrical properties also.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2012.05a
• /
• pp.257-257
• /
• 2012

Cerium doped anatase titania powders were prepared by sol-gel process, with ammonium (IV) nitrate and Titanium (IV) butoxide as the raw materials. The characteristics of anatase $TiO_2$ and cerium doped $TiO_2$ were investigated by XRD, DTA, FE-SEM and UV/Vis spectroscopy. Research results indicated that XRD data characteristic diffraction peaks of anatase phase and also showed that cerium phase was not observed. Moreover XRD and DTA results imply that the addition of cerium to titania modifies the mechanism of formation of the titania phases.

• The Korean Journal of Ceramics
• /
• v.6 no.2
• /
• pp.91-95
• /
• 2000

Powder mixtures of $\beta$-SiC-TiC in a weight ratio of 2:1 containing 5-20 wt% additives ($Al_2O_3$-$Y_2O_3$) were liquid-phase sintered at $1830^{\circ}C$ for 1h by hot-pressing and subsequently annealed at $1950^{\circ}C$ for 6h to enhance grain growth. The annealed specimens revealed a microstructure of \"in situ-toughened composite\" as a result of the $\beta$longrightarrow$\alpha$ phase transformation of SiC during annealing. The increase of the content of additives accelerated the growth of elongated $\alpha$-SiC grains with higher aspect ratio and improved fracture toughness. The fracture toughness of SiC-TiC composite containing 20 wt% additive was 6.2 MPa.$m^{1/2}$.2}$.

• Journal of Applied Biological Chemistry
• /
• v.49 no.4
• /
• pp.157-161
• /
• 2006

The performance of abiotic degradation of oxadiazon was investigated by applying zerovalent iron(ZVI), potassium permanganate($KMnO_4$) and titanium dioxide($TiO_2$) in the contaminated water. Experimental conditions allowed the disappearance of oxadiazon in the abiotic system. The degradation of this herbicide was monitored in buffer solutions having pH 3, 5 and 7 in the presence of iron powder in which the maximum degradation rate was achieved at acidic condition(pH 3) by 2% of ZVI treatment. The oxidative degradation of oxadiazon was observed in aqueous solution by $KMnO_4$ at pH 3, 7 and 10 in which the highest disappearance rate was found at neutral pH when treated with 2% of $KMnO_4$. The catalytic degradation of oxadiazon in $TiO_2$ suspension was obtained under dark and UV irradiation conditions. UV irradiation enhanced the degradation of oxadiazon in aquatic system in the presence of $TiO_2$. Conclusively, the remediation strategy using these abiotic reagents could be applied to remove oxadiazon from the contaminated water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.1148-1151
• /
• 2002

Dielectric ceramics with nominal composition of $(Ba_{0.93}Sr_{0.07}O)-0.5Sm_2O_3-4.5TiO_2$ was prepared using the conventional mixed oxide process-derived powder. Effect of $SiO_2$, $MnO_2$ and $Al_2O_3$ impurity addition on the microwave properties was examined in some detail. Measured relative permittivity $(\varepsilon_r)$ values were in the range of 53 to 59 and showed little dependence on impurity addition. In contrast, quality factor $(Q{\cdot}f)$ and temperature coefficient of resonant frequency $(\tau_f)$ values were greatly influenced by the type and the amount of impurities. It was found that 0.1~0.2wt% addition of $Al_2O_3$ was most effective for improving the properties, where ${\varepsilon}_r$, $Q{\cdot}f$ and $\tau_f$ values were 57.7, 10000, and +7ppm/$^{\circ}C$, respectively.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.7
• /
• pp.1104-1108
• /
• 2007

Conducting Polypyrrole-lead titanate (PPy/PbTiO3) composites have been prepared by in situ deposition technique by placing different wt.% of fine grade powder of PbTiO3 (10, 20, 30, 40, and 50%) during polymerization of pyrrole. The composites formed were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), and these data indicate that PbTiO3 particles are dominating with an increase in crystallinity as well as thermal stability of the composites. The results on the low frequency dielectric studies which are obtained in the form of pressed pellet state are interpreted in terms of Maxwell Wagner polarization, which are responsible for the dielectric relaxation mechanism and frequency dependence of conductivity.

• Journal of the Korean Ceramic Society
• /
• v.23 no.3
• /
• pp.15-20
• /
• 1986

Formation of powders and electromechanical coupling factor of $Pb(Mn_{1/3} Sb_{2/3})_{0.08} Ti_{0.495}Zr_{0.425}O_3$ by hydro-thermal synthesis are described. The hydrothermal reactions each were accomplished at 12$0^{\circ}C$~25$0^{\circ}C$ for 5hours and sintering was accomplished at 1, .20$0^{\circ}C$ for 1hours. The PZT powders by hydrothermal synthesis were formed above 16$0^{\circ}C$ and the forms were cubic types. The ratio of grain size of sintered sample to powder was slowly decreased with the rising of hydrothermal reactino temperature but decreased rapidly above 22$0^{\circ}C$ Sintering density was decreased with the rising of hydrothermal reaction temperature above 16$0^{\circ}C$ but dielectric constant was increased. Electromechanical coupling factor $K_P$ was almost constant at 16$0^{\circ}C$~24$0^{\circ}C$ range and the value of $K_P$ was about 0.43-0.45.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.11a
• /
• pp.202-203
• /
• 2005

To recognize whether admixture affects some $(Ba_{0.6}Sr_{0.4})TiO_3$, powder in this research $Li_2CO_3$, MgO, $MnO_2$ adding each 3 wt % by Tape casting method thick film make. Sitering temperature lowered 1300$^{\circ}C$ adding $Li_2CO_3$, and density is 5.942g/$cm^3$, and specific inductive capacity increases about decuple and displayed 4000. Climbed sitering temperature 1400$^{\circ}C$ adding MgO, specific inductive capacity reduced 1/2 times. Lowered sintering temperature 1325$^{\circ}C$ low adding $MnO_2$.

• Journal of the Korean institute of surface engineering
• /
• v.29 no.6
• /
• pp.695-702
• /
• 1996

Plasma spraying process was employed to produce HA coating on Ti6A14V alloy for the development of a dental implant. The goal of this research was to find optimum spraying conditions for HA coating on Ti6Al4V. This study was thus designed carefully to evaluate how spraying parameters affect various physical properties of a HA coating layer, such as phase composition and bond strength. In plasma spraying, spraying parameters such as hydrogen flow rates and spraying distances were varied systematically to change the degree of the melting of starting HA powder in plasma jet. It was revealed that the deposition efficiency increased with increasing a hydrogen flow rate, and the bond strength between the HA-coated layer and Ti-alloy substrate increased with hydrogen flow rate, but decreased with spraying distance. Therefore, the hydrogen flow rate and the spraying distance should be carefully controlled to obtain the reasonable bond strength simultaneously.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.2
• /
• pp.110-113
• /
• 2008

Embedded capacitor technology is one of the effective packing technologies for further miniaturization and higher performance of electric packaging system. In this paper, the embedded capacitors were simulated and fabricated in 8-layered printed circuit board employing standard PCB processes. The composites of barium titanante($BaTiO_3$) powder and epoxy resin were employed for the dielectric materials in embedded capacitors. Theoretical considerations regarding the embedded capacitors have been paid to understand the frequency dependent impedance behavior. Frequency dependent impedance of simulated and fabricated embedded capacitors was investigated. Fabricated embedded capacitors have lower self resonance frequency values than that of the simulated embedded capacitors due to the increased parasitic inductance values. Frequency dependent capacitances of fabricated embedded capacitors were well matched with those of simulated embedded capacitors from the 100MHz to 10GHz range. Quality factor of 20 was observed and simulated at 2GHz range in the 10 pF embedded capacitors. Temperature dependent capacitance of fabricated embedded capacitors was presented.