• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.7
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• pp.473-478
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• 2001

Ferroelectric P $b_{0.99}$［(Z $r_{0}$ 6S $n_{0.4}$)/0.9/ $Ti_{0.1}$］0.98/N $b_{0.02}$ $O_3$(PNZST) thin films were deposited by a RF magnetron sputtering on L $a_{0.5}$S $r_{0.5}$Co $O_3$(LSCO)/Pt/Ti/ $SiO_2$/Si substrate using a PNZST target with excess PbO of 10 mole%. The crystallinity and electrical properties of the thin films annealed at various temperature and time were investigated. The thin films deposited at the substrate temperature of 500 $^{\circ}C$ and the power of 80 W were crystallized to a perovskite phase after rapid thermal annealing(RTA). The thin films annealed at 650 $^{\circ}C$ for 10 seconds in air exhibited the good crystal structures. The remanent polarization and coercive field of the PNZST capacitor were about 20 $\mu$C/$\textrm{cm}^2$ and 50 kV/cm, respectively. The reduction of the polarization after 2.2$\times$10$^{9}$ switching cycles was less than 10 %..10 %......

• Electrical & Electronic Materials
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• v.5 no.2
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• pp.207-215
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• 1992

본 연구에서 xPb(A $l_{0.5}$N $b_{0.5}$) $O_{3}$-(1-x)Pb(Z $r_{0.52}$ $Ti_{o.48}$) $O_{3}$계의 조성변화에 따른 유전 및 압전특성에 관해 실험한 결과 다음과 같은 결론을 얻었다. PAN의 첨가량이 증가함에 따라 c축은 수축되고 a축은 팽창하여 tetragonality는 감소하였고 grain의 크기와 Curie온도 또한 PAN의 첨가량에 따라 감소하였으나 밀도와 유전상수는 PAN의 양이 5mol%까지 증가하다가 그 이상에서는 감소하는 경향을 보였다. PAN의 첨가량이 증가함에 따라 시편의 비저항은 증가하였고 Kp는 PAN의 양이 5mol%첨가시 60%로 최대치를 보였으나 Qm은 최소치를 나타내었다.다.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.1
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• pp.29-35
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• 2013

A dense mixed ionic and electronic conducting ceramic membrane is one of the most promising materials because it can be used for separation of oxygen from the mixture gas. The $ABO_3$ perovskite structure shows high chemical stability at high temperatures under reduction and oxidation atmospheres. $BaCo_{1-x-y}Fe_xZr_yO_{3-{\delta}}$ (BCFZ) was well-known material as high mechanical strength, low thermal conductivity and stability in the high valence state. Glycine Nitrate Process (GNP) is rapid and effective method for powder synthesis using glycine as a fuel and show higher product crystallinity compared to solid state reaction and citrate-EDTA method. BCFZ was fabricated by modified glycine nitrate process. In order to control the burn-up reaction, $NH_4NO_3$ was used as extra nitrate. According to X-Ray Diffraction (XRD) results, BCFZ was single phase regardless of Zr dopants from y=0.1 to 0.3 on B sites. The green compacts were sintered at $1200^{\circ}C$ for 2 hours. Oxygen permeability, methane partial oxidation rate and hydrogen production ability of the membranes were characterized by using Micro Gas Chromatography (Micro GC) under various condition. The high oxygen permeation flux of BCFZ 1-451 was about $1ml{\cdot}cm^{-2}s^{-1}$. Using the humidified Argon gas, BCFZ 1-433 produced hydrogen about $1ml{\cdot}cm^{-2}s^{-1}$.

• Korean Journal of Materials Research
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• v.33 no.11
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• pp.465-474
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• 2023

The effects of La³⁺ substitution for Sr²⁺-site on the crystal structure and the dielectric properties of (Ba_0.7Sr_0.3-3x/2La_x) (Ti_0.9Zr_0.1)O₃ (BSLTZ) (0.005 ≤ x ≤ 0.02) ceramics were investigated. The structural characteristics of the BSLTZ ceramics were quantitatively evaluated using the Rietveld refinement method from X-ray diffraction (XRD) data. For the specimens sintered at 1,550 ℃ for 6 h, a single phase with a perovskite structure and homogeneous microstructure were observed for the entire range of compositions. With increasing La³⁺ substitution (x), the unit cell volume decreased because the ionic size of La³⁺ (1.36 Å) ions is smaller than that of Sr²⁺ (1.44 Å) ions. With increasing La³⁺ substitution (x), the tetragonal phase fraction increased due to the A-site cation size mismatch effect. Dielectric constant (ε_r) increased with the La³⁺ substitution (x) due to the increase in tetragonality (c/a) and the average B-site bond valence of the ABO₃ perovskite. The BSLTZ ceramics showed a higher dielectric loss due to the smaller grain size than that of (Ba_0.7Sr_0.3)(Ti_0.9Zr_0.1)O₃ ceramics. BSLTZ (x = 0.02) ceramics met the X7R specification proposed by the Electronic Industries Association (EIA).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.995-999
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• 2007

The lead zirconate titanate (PZT) powders were synthesized to make the piezoelectric ceramics in low temperature as low as $900^{\circ}C$. To investigate the influence of additives on sintering of PZT, two kinds of sintering aids were made as follows; $wB_2O_3-xBi_2O_3-zCuO$and LiBiO2-CuO. The sintering aid, $1{\sim}3$ wt.% $LiBiO_2-CuO$, was added into these PZT powders and the specimens were fired at temperature in the range of $800{\sim}1200^{\circ}C$. The highest density was shown in the specimen with 1 wt.% $LiBiO_2-CuO$ as additive at temperature of $900^{\circ}C$. The sintered specimen were analyzed by X-ray diffraction(XRD) and scanning electron microscopy (SEM) was utilized to observe the microstructure, especially the densified morphology of specimens. In the XRD pattern, the well-crystallized PZT phase could be obtained in consequence of firing at $900^{\circ}C$. The scanning electron microscopy(SEM) was utilized to observe the structure of specimens after firing at $900^{\circ}C$. The densified perovskite structure of $PbZrTiO_3$ could be obtained by sintering at temperature as low as $900^{\circ}C$. The high sinterability of PZT ceramics was attributed to the low formation temperature of the liquid phase of additives.

• Transactions of the Korean hydrogen and new energy society
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• v.8 no.1
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• pp.11-21
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• 1997

$ZrV_{0.7}Mn_{0.5}Ni_{1.2}$ alloy is attractive for anode material in Ni/MH secondary battery because of its large hydrogen storage capacity in gas-solid reaction and long cycling durability in KOH electrolyte. In this work, in order to further improve the discharge performance of this alloy electrode, the alloy was annealed by optimal condition which is for 12 hours at $1000^{\circ}C$. The alloy annealed under optimal condition had higher rate capability and discharge capacity than as-cast one. The microstructure of the as-cast and annealed alloy was investigated by scanning electron microscopy and energy dispersive spectroscopy. Ni content in the matrix was increased, being this homogenized after annealing. Additionally, The measurement of the surface area by B.E.T. analysis showed that there was little difference as-cast and annealed alloy. Therefore, improvement in the rate capability of the annealed alloy is due to increase of Ni content in the matrix.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.1
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• pp.37-41
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• 1991

In this study, the effect of solution treatment temperature on the tensile property in intermediate thermo-mechanical treated Al-Li alloys are investigated. After the intermediate thermo-mechanical treated Al-Li, Al-Li-Mg and Al-Li-Mg-Zr alloys were solution treated at various temperatures (500, 520 and $540^{\circ}C$), these were aged at $190^{\circ}C$, $240^{\circ}C$ and tested tensile properties. The results obtained from the experiment are as follows ; 1) The optimum solution heat-treatment temperature is $540^{\circ}C$ for a Al-Li alloy, and the recrystallized grain size is about $70{\mu}m$. 2) The optimum solution heat-treatment temperature is $500^{\circ}C$ for a Al-Li-Mg alloy, and the recrystallized grain size is the most coarse in all alloys. 3) The tensile property is independent of the solution treatment temperature in a Al-Li-Mg-Zr alloy, and the recrystallized grain size is the finest owing to addition of Zr.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.2
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• pp.38-46
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• 1991

Effects of aging treatment on the microstructures and microhardness of a rapidly solidified Al-Li-Cu-Mg-Zr alloy were investigated by differential scanning calorimetry(DSC) and transmission electron microscopy(TEM). The as-melt-spun ribbon was consisted of fine ${\delta}^{\prime}$ and icosahedral intermetallic compound which were precipitated in the matrix. Two exothermic peaks with the range of $120^{\circ}C-190^{\circ}C$ and $280^{\circ}C-344^{\circ}C$ corresponded to ${\delta}^{\prime}$ and ${\theta}^{\prime}$, S', $T_1$ precipitating reaction respectively, and two endothermic peaks with the range of $190^{\circ}C-280^{\circ}C$ and $344^{\circ}C-550^{\circ}C$ corresponded to dissolution of ${\delta}^{\prime}$ and ${\theta}^{\prime}$, S', $T_1$ respectively in DSC curves. Peak hardness value was obtained at $210^{\circ}C$ for 1 hr aging treatment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.5
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• pp.193-198
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• 2004

Using the $PbO-B_2O_3-Bi_2O_3$ flux system, $(TbBi)_3(FeAIGa)_5O_{12}(TbIG)$, $(EuBi)_3(FeAIGa)_5O_{12}(EuIG)$ and $(EuTbBi)_3(FeAIGa)_5O_{12}(EuTbIG)$ films were grown on $(GdCa)_3(GaMgZr)_5O_{12}(SGGG)$ substrates by the liquid phase epitaxy (LPE). The saturation magnetization of the grown TbIG, EuIG and EuTbIG films was about 150, 950 and 125 Oe, respectively. The TbIG films resulted in the single magnetic domain while the EuIG and EuTbIG films were observed to be the multi magnetic domains by magnetic force microscope (MFM).

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1127-1132
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• 2010

Borosilicate glass was prepared in the composition of 81% $SiO_2$, 4% $Na_2O$, 2% $Al_2O_3$, 13% $B_2O_3$. The albite phase($NaAlSi_3O_8$) increased with the $ZrO_2$(0~10wt.%) addition. For measurement of glass transition temperature($T_g$), crystallization temperature($T_{c,max}$) measured by differential thermal analysis. The $T_g$ and $T_{c,max}$ were $510{\sim}530^{\circ}C$ $650{\sim}670^{\circ}C$, respectively. The crystallized glass was heated at various conditions(temperature, time). After nucleation at $550^{\circ}C$ for 2hours prior to crystal growth at $650^{\circ}C$ for 4hours, the resulting Vickers hardness, fracture toughness and bending strength were about $736H_v$, $1.0779MPa{\cdot}m^{1/2}$, and 493MPa, which were 17%, 45% and 149% higher than parent borosilicate glass, respectively. Crystal size and transmittance of crystallized borosilicate glass were analyzed by FE-SEM, EDX and UV-VIS-NIR spectrophotometer. Transmittance of crystallized borosilicate glass was decreased with increasing $ZrO_2$(wt%) at visible-range. The results prove that light-weight bulletproof can be fabricated by the crystallization of borosilicate glass.