• Journal of Nuclear Fuel Cycle and Waste Technology
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• v.1 no.1
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• pp.57-63
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• 2013

Natural green rust (GR) can retard the migration of anions through geological media because it has a Layer Double Hydroxyl (LDH) structure with a positive charge. In this study, the sorption behaviors of anions such as selenite ($Se(IV)O{_3}^{2-}$), selenate ($Se(VI)O{_4}^{2-}$), and iodide ($I^-$) onto green rusts with different structures, i.e., GR($Cl^-$) and GR($CO{_3}^{2-}$), were investigated by conducting batch sorption experiments in an anoxic condition. Experimental results showed that selenite was mostly sorbed onto GR($CO{_3}^{2-}$) and then partly reduced to metal selenium, Se(0). However, little selenate and iodide was sorbed onto GR($CO{_3}^{2-}$) while some iodide was sorbed onto GR($Cl^-$). It is presumed from the experimental results that the major sorption mechanism of $SeO{_3}^{2-}$ and $I^-$ onto green rusts is the anion exchange reaction with the anions existing in the interlayer of the rusts. Green rust, therefore, can play an important role in the retardation of anions migrating through deep geological environments owing to its LDH structure with a high anion exchange capacity.

• Korean Journal of Materials Research
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• v.19 no.8
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• pp.452-456
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• 2009

In high-efficiency Cu(In,Ga)$Se_2$ solar cells, Na is doped into a Cu(In,Ga)$Se_2$ light-absorbing layer from sodalime-glass substrate through Mo back-contact layer, resulting in an increase of device performance. However, this supply of sodium is limited when the process temperature is too low or when a substrate does not supply Na. This limitation can be overcome by supplying Na through external doping. For Na doping, an NaF interlayer was deposited on Mo/glass substrate. A Cu(In,Ga)$Se_2$ absorber layer was deposited on the NaF interlayer by a three-stage co-evaporation process As the thickness of NaF interlayer increased, smaller grain sizes were obtained. The resistivity of the NaF-doped CIGS film was of the order of $10^3{\Omega}{\cdot}cm$ indicating that doping was not very effective. However, highest conversion efficiency of 14.2% was obtained when the NaF thickness was 25 nm, suggesting that Na doping using an NaF interlayer is one of the possible methods for external doping.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.19-23
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• 2019

The PMMA (polymethyl methacrylate)/clay nanocomposites were synthesized by in situ radical polymerizations with different clay contents (3 and 7 wt%) using microwave heating. The nanostructure, optical, and thermal properties of the synthesized PMMA/clay nanocomposites were measured by XRD, TEM, AFM, UV-vis, and TGA. It was found that the intercalated- or exfoliated structure of PMMA/clay nanocomposites was strongly dependent on the content of clay. Thus, the imposition of microwave-assisted polymerization facilitated a delamination process of layered silicates to achieve exfoliation state of interlayer distance. The PMMA/3 wt% C10A nanocomposite with well-dispersed and exfoliated clay nano-layers showed the good optical transparency similar to pure PMMA in this study. The thermal decomposition rates of the PMMA/clay nanocomposites become to be lower compared to that of the pure PMMA, indicating the intercalated- or exfoliated inorganic silicate has high thermal stability. A possible reason is that the thermally segmental motion of PMMA polymer into inorganic silicate interlayer spacing has increased the thermal stability of the PMMA/clay nanocomposites.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.702-709
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• 1995

In this paper we review recent work in our laboratory on nanocomposite CoSm-based films including CoSm with Cr underlayer (CoSm//Cr), exchange-coupled magnetic films consisting of CoSm and FeCo layers (CoSm/FeCo), and CoSm multilayers with nonmagnetic spacing layers of SmO (CoSm/SmO). The emphasis is on detailed investigations of microstructure and magnetic properties for CoSm//Cr films, exchange-spring effects for CoSm/FeCo films, and interlayer effects for (CoSm/ SmO) multilayers.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.336-345
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• 2020

Nickel-doped lanthanum cobalt oxide (LaCo_1-xNi_xO_3-δ, LCN) was investigated as an alternative anode material for solid oxide fuel cells. To improve its catalytic activity for steam methane reforming (SMR) reaction, Ni²⁺ was substituted into Co³⁺ lattice in LaCoO₃. LCN anode, synthesized using the Pechini method, reacts with yttria-stabilized zirconia (YSZ) electrolyte at high temperatures to form an electrochemically inactive phase such as La₂Zr₂O₇. To minimize the interlayer by-products, the LCN was coated via a double-tape casting method on the Ni/YSZ anode as a catalytic functional layer. By increasing the Ni doping amount, oxygen vacancies in the LCN increased and the cell performance improved. CH₄ fuel decomposed to H₂ and CO via SMR reaction in the LCN functional layer. Hence, the LCN-coated Ni/YSZ anode exhibited better cell performance than the Ni/YSZ anode under H₂ and CH₄ fuels. LCN with 12 mol% of Ni (LCN12)-modified Ni/YSZ anode showed excellent long-term stability under H₂ and CH₄ conditions.

• Macromolecular Research
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• v.11 no.6
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• pp.425-430
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• 2003

Two types of poly(n-butyl acrylate) copolymer/silicate nanocomposites have been produced: poly(n-butyl acrylate-co-methyl methacrylate) [P(BA-co-MMA)]/silicate nanocomposites and poly(n-butyl acrylate-co-styrene) [P(BA-co-ST)]/silicate nanocomposites. The P(BA-co-MMA)/silicate nanocomposites shows the exfoliated structures but a P(BA-co-ST)/silicate nanocomposites have intercalated structures, because the BA/MMA comonomer has a higher polarity (e-value in Q-e scheme) than the BA/ST comonomer. The BA/MMA comonomer expanded the interlayer space of the silicate wider than did the BA/ST comonomer. The thermal degradation onset point of the P(BA-co-MMA)/silicate nanocomposites was 43$^{\circ}C$ higher than that of pure P(BA-co-MMA). P(BA-co-MMA)T5%, P(BA-co-MMA)T10%, and P(BA-co-MMA)T20% exhibit 134,302, and 195% increases, respectively, in their storage moduli at -20$^{\circ}C$ relative to the pure copolymer.

• Journal of the Korean Ceramic Society
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• v.36 no.6
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• pp.604-610
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• 1999

Silicide layer structures and morphology degradation of the surface and interface of the silicide layers for he Co/refractory metal bilayer sputter-deposited on the P-doped polycrystalline Si substrate and subjected to rapid thermal annealing were investigated and compared with those on the single Si substrate. The CoSi-CoSi2 phase transition temperature is lower an morphology degradation of the silcide layer occurs more severely for the Co/refractorymetal bilayer on the P-doped polycrystalline Si substrate than on the single Si substrate. Also the final layer structure and the morphology of the films after silicidation annealing was found to depend strongly upon the interlayer metal. The layer structure after silicidation annealing of Co/Hf/doped-poly Si is Co-Hf alloy/polycrystalline CoSi2/poly Si substrate while that of Co/Nb is polycrystalline CoSi2/NbSi2/polycrystalline CoSi2/poly Si.

• Journal of the Korean Magnetics Society
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• v.14 no.6
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• pp.236-239
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• 2004

We studied the specular spin valve (SSV) having the spin filter layer (SFL) in contact with the ultrathin free layer composed of Ta3/NiFe2/IrMn7/CoFel/(NOLl)/CoFe2/Cu1.8/CoFe( $t_{F}$)/Cu( $t_{SF}$ )/(NOL2)/Ta3.5 (in nm) by the magnetron sputtering system. For this antiferromagnetic I $r_{22}$M $n_{78}$-pinned spin filter specular spin valve (SFSSV) films, an optimal magnetoresistance (MR) ratio of 11.9% was obtained when both the free layer thickness ( $t_{F}$) and the SFL thickness ( $t_{SF}$ ) were 1.5 nm, and the MR ratio higher than 11% was maintained even when the $t_{F}$ was reduced to 1.0 nm. It was due to increase of specular electron by the nano-oxide layer (NOL) and of current shunting through the SFL. Moreover, the interlayer coupling field ( $H_{int}$) between free layer and pinned layer could be explained by considering the RKKY and magnetostatic coupling. The coercivity of the free layer ( $H_{cf}$ ) was significantly reduced as compared to the traditional spin valve (TSV), and was remained as low as 4 Oe when the $t_{F}$ varied from 1 nm to 4 urn. It was found that the SFL made it possible to reduce the free layer thickness and enhance the MR ratio without degrading the soft magnetic property of the free layer.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.166-166
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• 2003

Si (100) 기판위에서 에피텍셜하게 자란 CoSi$_2$층은 우수한 열적안정성, 낮은 junction leakage, ultra-Shallow junction형성 등의 장점으로 인하여 많은 주목을 받아왔다. 그래서 에피텍셜 CoSi$_2$층을 형성하기 위한 많은 방법들이 보고되어 왔다. 그 방법으로는 Ti나 TiN층을 이용한 interlayer mediated epitaxy, Co의 제한적 공급을 통한 molecular beam epitaxy와 molecular beam allotaxy, 그리고 금속유기소스를 이용한 반응성화학기상증착법등이 있다. 하지만 이 방법들은 복잡한 증착공정과 열처리 후 잔류층 제거의 어려움등을 가지고 있다. 본 연구는 일반적으로 사용되는 Ti나 oxide의 중간층없이 에피층을 형성시키는 새로운 방법으로 CO-O-N 박막으로부터 열처리에 의해 확산된 Co로부터 CoSi$_2$에피층을 형성시켰다.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.72-72
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• 2004