• Transactions on Electrical and Electronic Materials
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• v.16 no.1
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• pp.1-4
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• 2015

(111)-oriented and random oriented $Pb_{0.8}Ba_{0.2}ZrO_3$ (PBZ) perovskite relaxor ferroelectric thin films were fabricated on Pt(111)/$TiO_x$/$SiO_2$/Si substrate by sol-gel method. Nano-scaled antiferroelectric and ferroelectric two-phase coexisted in both (111)-oriented and random oriented PBZ thin film. High dielectric tunability (${\eta}=75%$, E = 560 kV/cm) and figure-of-merit (FOM ~ 236) at room temperature was obtained in (111)-oriented thin film. Meanwhile, giant electrocaloric effect (ECE) (${\Delta}T=45.3K$ and ${\Delta}S=46.9JK^{-1}kg^{-1}$ at $598kVcm^{-1}$) at room temperature (290 K), rather than at its Curie temperature (408 K), was observed in random oriented $Pb_{0.8}Ba_{0.2}ZrO_3$ (PBZ) thin film, which makes it a promising material for the application to cooling systems near room temperature. The giant ECE as well as high dielectric tunability are attributed to the coexistence of AFE and FE phases and field-induced nano-scaled AFE to FE phase transition.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.538-544
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• 1998

The spallation of a thermal barrier coating layer depends on the formation of brittle spinels. thermal expansion mismatch between ceramic and metal. the phase transformation of a ceramic layer and residual stress of coating layer. In this work. the formation mechanism of oxide scale formed by oxidation treatment at 90$0^{\circ}C$ was investigated in order to verify oxidation behavior at the interface between E-beam coated $Zr0_2$-7wt.% $Y_20_3$ and plasma sprayed CoNiCrAIY. Some elements distributed in the bond coating layer were selectively oxidized after oxidation. At the initial time of oxidation. AI-depletion zone and $\alpha$-$Al_O_3$,O, were formed at the bond coating layer by the AI-outward diffusion. After layer grew until critical thickness. spinels. $Cr_20$, and $C0_2CrO_4$ by outward diffusion of Co. Cr, Ni were formed. It was found that the formation of spinels may be related to the spallation of $Zr0_2$-7wt.% $Y_20_3$ during isothermal oxidation.

• Journal of Radiation Protection and Research
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• v.8 no.2
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• pp.15-35
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• 1983

High voltage paper-electrophoresis of fission products from 24 hour neutron-irradiated and 150 days-decayed 90% highly enriched uranyl nitrate solution has been carried out by using the specially designed migration apparatus. The separation of Zr-95 and Nb-95 from the other fission products is possible under the migration condition of 0.1 $M-HClO_4$ (pH=0.85), 0.05 M-HCl+0.09M-KCl (pH=0.9), 0.1M-HCl (pH=1.1) and 0.01 M-HCl (pH=2.0). Zr-95 and Nb-95 are separated out at+1cm from the fiducial point. The separation of Zr-95 and Nb-95 from each other is possible under the migration condition of 0.1 $M-HClO_4$, 0.05 M-HCl+0.09 M-KCl, 0.1 M-HCl and 0.1 M-HAc+0.1 M-NaAc (pH=4.68) together with 2% ammonium oxalate. Nb-95 is separated out at $-6{\sim}-7cm$ from the fiducial point and Zr-95 at $+1{\sim}-lcm$. The separation of Ru-103 from the other fission products is possible under the migration condition of 0.025 $M-Na_2CO_3+0.025\;M-NaHCO_3$ (pH=10.0), 0.01M-$Na_3PO_4$ (pH=11.7) and 0.1 M-NaOH (pH=13.2). Ru-103 migrates towards the anode -6cm, -4cm and -3cm, respectively.

• Macromolecular Research
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• v.8 no.5
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• pp.238-242
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• 2000

The new trisiloxane-bridged heterometallic dinuclear metallocenes, hexamethyltrisiloxanediyl(cyclopentadienyltitanium trichloride) (cyclopentadienylindenyl zirconium dichloride) , $C_3ITi-Cp(CH_3)_2Si-O-Si(CH_3)_2-O-Si(CH_3)_2-Cp-ZrIndCI_2$ (1) and hexamethyltrisiloxanediyl (cyclopentadienylindenylhafnium dichloride) (cyclopentadienylindenyl zirconium dichloride), $C_2IndHf-Cp(CH_3)_2Si-O-Si(CH_3)_2-Cp-ZrIndCl_2$ 2) connecting two dissimilar metallocenes were synthesized and used for ethylene polymerization in the presence of modified methylaluminoxane (MMAO) cocatalyst. The catalytic activity of heterometallic dinuclear metallocenes, 1 and 2 was lower than that of corresponding mononuclear metal-locene as well as two physically mixed catalysts, $CpTiCl_2/Cp_2ZrCl_2 and Cp_2HfCl_2/Cp_2ZrCl_2$. On the tither hand, MWD of PE obtained with 1 and 2 was remarkably broader ($M_w/M_n$) became up to 9.4) than those of PEs prepared with the corresponding mononuclear metallocenes and mixed catalysts. With analysis by GPC and CFC, it was found that PE produced by the heterometallic dinuclear metallocenes exhibited the definite bimodal GPC curves that should cause the broadening of MWD.

• Journal of the Korean Ceramic Society
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• v.56 no.1
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• pp.91-97
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• 2019

The effect of different Ni-containing additives on the sintering behavior and electric conductivity of the proton conducting electrolyte $BaCe_{0.35}Zr_{0.5}Y_{0.15}O_{3-{\delta}}$ (BCZY5) was investigated. Ni-doped, NiO-added, and $BaY_2NiO_5$(BYN)-added (all 4 mol%) BCZY5 samples were prepared by the solid state synthesis method and sintered at $1400^{\circ}C$ for 6 h. Among the three samples, the onset of densification was observed at the lowest temperature for NiO-added BCZY5, which is attributed to the formation of an intermediate phase at a low melting temperature. The BYN-added sample, where no consumption of the constitutional elements of the electrolyte was expected during sintering, exhibited the highest electrical conductivity whereas the doped sample had the lowest conductivity. The electrical conductivities at $500^{\circ}C$ under humid argon atmosphere were measured to be 2.0, 4.8, and $6.2mS{\cdot}cm^{-1}$ for Ni-doped and NiO- and BYN-added samples, respectively.

• Electrical & Electronic Materials
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• v.6 no.6
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• pp.573-581
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• 1993

0.10Pb(Sb$_{1}$2/Sn$_{1}$2/)O$_{3}$-0.25PbTiO$_{3}$-0.65PbZrO$_{3}$ 세라믹을 소결온도 및 시간을 각각 1200-1250[.deg.C]에서 2, 4, 6시간으로 변화시켜 제작하였으며 시편의 소결조건 및 MnO$_{2}$(0~0.30mol%)첨가량에 따른 잡음특성을 관찰하였다. 초전계수 및 전압감도는 1250[.deg.C]에서 2시간 소결시킨 시편에서 각각 3.49x$10^{-8}$[C/$cm^{2}$K], 147[V/W]의 최대값을 나타내었다. 초전형 적외선 검출기의 잡음특성에 있어 증폭기의 전류잡음 .DELTA.V$_{i}$가 총 잡음전압에 대해 지배적인 경향을 나타내었으며 MnO$_{2}$가 0.24[mol%] 첨가된 1250[.deg.C]에서 2시간 소결시킨 시편에서 가장 양호한 pop-corn잡음특성을 나타내었다.다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.836-839
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• 2001

Ba(Zr$_{x}$Ti$_{l-x}$)O$_3$(BZT) thin films of x=0.2 and 150nm thickness were prepared on Pt/SiO$_2$/Si substrate by RF Magnetron Sputtering deposition at several temperature (40$0^{\circ}C$, 50$0^{\circ}C$, $600^{\circ}C$). As the substrates temperature increase, crystallization of the films and high dielectric constants can be obtained. Capacitance of the film deposited at high temperature is more sensitive to the applied voltage than that of the film deposited at low temperature, and the film's breakdown voltage is higher in low temperature.ure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.106-111
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• 2005

Failure mechanisms were investigated for the two layer thermal barrier coatings consisting of NiCrAlY bond coat and $ZrO_2-8wt.\% Y_{2}O_3$ ceramic coating during cyclic oxidation. $Al_{2}O_3$ developed at the ceramic coating/bond coat interface first, followed by the Cr/Ni rich oxides such as $NiCr_{2}O_4 and Ni(Al,Cr)_{2}O_4$ during cyclic oxidation It was observed that the spalling of ceramic coatings took place primarily within the NiCrAlY bond coat oxidation products or at the interface between the bond coat oxidation products and zirconia based ceramic coating or the bond coat. It was also observed that the fracture within these oxidation products occurred with the formation of $Ni(Cr,Al)_{2}O_4$ spinel or Cr/Ni rich oxides. It was therefore concluded that the formation of these oxides was a life-limiting event for the thermal barrier coatings.

• Journal of Sensor Science and Technology
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• v.4 no.4
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• pp.75-80
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• 1995

In order to fabricate the piezoelectric thin film of the PZT-PNN ternary compound, the metal alkoxides were used as starting materials. The electrical and crystalline properties of the thin film were evaluated. The X- RD study shows that the crystallization of the film is optimized at $550^{\circ}C$ of sintering temperature. According to the D-E hysterisis curve, the coercive field is 28.8 kV /cm, and the remanent polariztion is $18.3\;{\mu}C/cm^{2}$. The break down voltages of the thin films are $76.0\;{\sim}\;27.0\;MV/m$. When the sintering temperature is raised, the break down voltage is lowered. As a result of measuring the C-V characteristic curve of the ternary compound piezoelectric thin film, the relative dielectric constants are 406 for the composition (50:40:10), 1084 for the composition (50:30:20), 723 for the composition (45:35:20) and 316 for the composition (40:40:20).

• The Korean Journal of Ceramics
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• v.4 no.4
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• pp.340-344
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• 1998

Failure mechanisms were investigated for the two layer thermal barrier coatings consisting of NiCrAlY bond coat and $ZrO_2$-8wt.% $Y_2O_3$ ceramic coating during cyclic oxidation. $Al_2O_3$ developed at the ceramic coating/bond coat interface first, followed by the Cr/Ni rich oxides such as $NiCr_2O_4$ and $Ni(Al, Cr)_2O_4$ during cyclic oxidation. It was observed that the spalling of ceramic coatings took place primarily within the NiCrAlY bond coat oxidation products or at the interface between the bond coat oxidation products and zirconia based ceramic coating or the bond coat. It was also observed that the fracture within these oxidation products occurred with the formation of $Ni(Cr, Al)_2O_4$ spinel or Cr/Ni rich oxides. It was therefore concluded that the formation of these oxides was a life-limiting event for the thermal barrier coatings.