• Proceedings of the KIEE Conference
• /
• 2006.10a
• /
• pp.123-124
• /
• 2006

The sandwiched PZT/$BaTiO_3$/PZT thick films were fabricated by two different methods thick films of the PZT by screen printing method on alumina substrateselectrodes with Pt, thin films of $BaTiO_3$ by the spin-coating method on the PZT thick films and once more thick films of the PZT by the screen printing method on the $BaTiO_3$ layer. The structural and the dielectric properties were investigated for effect of various stacking sequence of sol-gel prepared $BaTiO_3$ coating solution at interface of the PZT thick films, The insertion of BaTi03 interlayer yielded the PZT thick films with homogeneous and dense grain structure with the number of $BaTiO_3$ layers. The leakage current density of the $PZT/BaTiO_3-1$ film is less that $4.41{\times}10^{-9}A/cm^2$ at 5 V.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.5C no.3
• /
• pp.119-123
• /
• 2005

Lithium titanium oxide as anode material for energy storage prepared by novel synthesis method. Li$_{4}$Ti$_{5}$O$_{12}$ based spinel-framework structures are of great interest material for lithium-ion batteries. We describe here Li$_{4}$Ti$_{5}$O$_{12}$ a zero-strain insertion material was prepared by novel sol-gel method and by high energy ball milling (HEBM) of precursor to from nanocrystalline phases. According to the X-ray diffraction and scanning electron microscopy analysis, uniformly distributed Li$_{4}$ Ti$_{5}$O$_{12}$ particles with grain sizes of 100nm were synthesized. Lithium cells, consisting of Li$_{4}$ Ti$_{5}$O$_{12}$ anode and lithium cathode showed the 173 mAh/g in the range of 1.0 $\~$ 3.0 V. Furthermore, the crystalline structure of Li$_{4}$ Ti$_{5}$O$_{12}$ didn't transform during the lithium intercalation and deintercalation process.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.6
• /
• pp.652-660
• /
• 1992

0.10Pb(SbS11/2TSnS11/2T)OS13T-0.25PbTiOS13T-0.65PbZrOS13T ceramics modified by LaS12TOS13T(1[mol%]) and MnOS12T(0-0.30[mol%]) were fabricated. The structural and pyroelectric properties with contents of MnOS12T were studied. Crystal structure of a specimen was rhombohedral type and average grain sizes were decreased with increasing the contents of MnOS12T. Relative dielectric constant and dielectric loss factor were minimum in the specimens doped 0.24[mol%]MnOS12T. (PbS10.99TLaS10.01T)[(SbS11/2TSnS11/2T) TiS10.25TZrS10.65T]OS13T specimen modified 0.24[mol%]MnOS12T showed the good pyroelectric properties and pyroelectric coefficient and voltage responsivity were 6.73x10S0-8T[C/cmS02TK], 125[V/W], respectively. Voltage responsivity was increased with decreasing the chopper frequency.

• Electrical & Electronic Materials
• /
• v.8 no.6
• /
• pp.737-743
• /
• 1995

Two step RTD(Rapid Thermal Diffussion) of P into silicon wafer using tungsten halogen lamp was used to fabricated very shallow n$^{+}$p junction. 1st RTD was performed in the temperature range of 800.deg. C for 60 see and the heating rate was in the 50.deg. C/sec. Phosphrous solid source was transfered on the silicon surface. 2nd RTD process was performed in the temperature range 1050.deg. C, 10sec. Using 2 step RTD we can obtain a shallow junction 0.13.mu.m in depth. After RTD, the Ti-silicide process was performed by the two step RTA(Rapid Thermal Annealing) to reduced the electric resistance and to improve the n$^{+}$p junction diode. The titanium thickness was 300.angs.. The condition of lst RTA process was 600.deg. C of 30sec and that of 2nd RTA process was varied in the range 700.deg. C, 750.deg. C, 800.deg. C for 10sec-60sec. After 2 step RTA, sheet resistance was 46.ohm../[]. Ti-silicide n+p junction diode was fabricated and I-V characteristics were measured.red.

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.1989-1991
• /
• 2005

Lithium titanium oxide as anode material for energy storage prepared by novel synthesis method. $Li_4Ti_5O_{12}$ based spinel-framework structures are of great interest material for lithium-ion batteries. We describe here $Li_4Ti_5O_{12}$ a zero-strain insertion material was prepared by novel sol-gel method and by high energy ball milling (HEBM) of precursor to from nanocrystalline phases. According to the X-ray diffraction and scanning electron microscopy analysis, uniformly distributed $Li_4Ti_5O_{12}$ particles with grain sizes of 100nm were synthesized. Lithium cells, consisting of $Li_4Ti_5O_{12}$ anode and lithium cathode showed the 173 mAh/g in the range of $1.0{\sim}3.0V$. Furthermore, the crystalline structure of $Li_4Ti_5O_{12}$ didn't transfer during the lithium intercalation and deintercalation process.

• Journal of Powder Materials
• /
• v.17 no.6
• /
• pp.464-469
• /
• 2010

The Cu nanofluid in ethylene glycol was prepared by electrical explosion of wire, a novel one-step method. The X-ray diffraction, field emission scanning electron microscope and transmission electron microscope were used to study the properties of Cu nanoparticles. The results showed that the nanoparticles were consisted of pure face-centered cubic structure and near spherical shape with average grain size of 65 nm. Ultraviolet-visible spectroscopy (UV-Vis) confirmed Cu nanoparticles with a single absorbance peak of Cu surface plasmon resonance band at 600 nm. The nanofluid was found to be stable due to high positive zeta potential value, +51 mV. The backscattering level of nanofluid in static stationary was decreased about 2% for 5 days. The thermal conductivity measurement showed that Cu-ethylene glycol nanofluid with low concentration of nanoparticles had higher thermal conductivity than based fluid. The enhancement of thermal conductivity of nanofluid at a volume fraction of 0.1% was approximately 5.2%.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.3
• /
• pp.1009-1015
• /
• 2014

Chalcopyrite $CuInSe_2$ (CIS) thin films were prepared without Se- / S-containing gas by co-sputtering using $CuSe_2$ and $InSe_2$ selenide-targets and rapid thermal annealing. The grain size increased to a maximum of 54.68 nm with a predominant (112) plane. The tetragonal distortion parameter ${\eta}$ decreased and the inter-planar spacing $d_{(112)}$ increased in the RTA-treated CIS thin films annealed at a $400^{\circ}C$, which indicates better crystal quality. The increased carrier concentration of RTA-treated p-type CIS thin films led to a decrease in resistivity due to an increase in Cu composition at annealing temperatures ${\geq}350^{\circ}C$. The optical band gap energy ($E_g$) of CIS thin films decreased to 1.127 eV in RTA-treated CIS thin films annealed at $400^{\circ}C$ due to the improved crystallinity, elevated carrier concentration and decreased In composition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.382-383
• /
• 2006

The tungsten bronze type of strontium barium niobate(SBN) thin film was synthesized by metal organic decomposion method for SBN stock solution and the SBN thin film process were deposited by spin-coating process on Pt-deposited si-wafer(100) by magnetron sputtering system. The thickness of SBN thin film was 150~200 nm and were optimized for rpm of spin-coater system. The structural variation of SBN thin film was studied by TG-DTA and XRD. The deposited SBN stock solution on annealing at $400{\sim}800^{\circ}C$ a pure tungsten bronze SBN phase and the corresponding. average grain size about 500~1000 nm influenced by annealing temperature. The piezoelectric properties of prepared SBN thin film, the remanent polarization value(2Pr) and coercive field was $1.2{\mu}C/cm^2$ and 2.15V/cm, respectively.

• Journal of the Korean Physical Society
• /
• v.73 no.10
• /
• pp.1535-1540
• /
• 2018

In this study, we prepared and characterized Nb-doped $Li_7La_3Zr_{2-x}O_{12}$ (LLZNO) powder and pellets with a cubic garnet structure by using a modified sol-gel synthesis and hot pressing. LLZNO powder with a very small grain size and cubic structure without secondary phases could be obtained by using a synthesis method in which Li and La sources in a propanol solvent were mixed together with Zr and Nb sources in 2-methoxy ethanol. A pure cubic phase LLZNO pellet could be fabricated from the prepared LLZNO and an additional 6-wt% of $Li_2CO_3$ powder by hot pressing at $1050^{\circ}C$ and 15.8 MPa. The hot-pressed LLZNO pellet with a relative density of 99% exhibited a very dense surface morphology. The total Li ionic conductivity of the hot-pressed LLZNO was $7.4{\times}10^{-4}S/cm$ at room temperature, which is very high level compared to other reported values. The activation energy for ionic conduction was estimated to be 0.40 eV.

• Nuclear Engineering and Technology
• /
• v.54 no.3
• /
• pp.991-996
• /
• 2022

Microstructures of monolithic high purity SiC and SiC with sintering additives after neutron irradiation to a fluence of 2.0-2.5 × 10²⁴ n/m² (E > 0.1 MeV) at 333-363 K and after post-irradiation annealing up to 1673 K were observed using a transmission electron microscopy. Results showed that no black spot defects or dislocation loops in SiC grains were found after the neutron irradiation for all of the specimens owing to the moderate fluence at low irradiation temperature. Thus, it is confirmed that these specimens were swelled mostly by the formation of point defects. Black spots and small dislocation loops were discovered only after the annealing process in PureBeta-SiC and CVD-SiC, where the swelling almost diminished. Anomalous-shaped YAG grains were found in SiC ceramics containing sintering additives. These grains contained dense black spots defects and might lose crystallinity after the neutron irradiation, while these defects may annihilate by recrystallization during annealing up to 1673 K. Amorphous grain boundary phase was also presented in this ceramic, and a large part of it was crystallized through post-irradiation annealing and could affect their recovery behavior.