• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.480-483
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• 2001

Epitaxial rutile-$TiO_2$ and anatase-$TiO_2$ films were grown at $800^{\circ}C$ on $Al_2O_3$ (1102) and $LaAlO_3$ (001), respectively, using pulsed laser deposition. The formation of different phases on different substrates could be qualitatively explained by the atomic arrangements at the interfaces. We also successfully deposited epitaxial rutile-$TiO_2$ and anatase-$TiO_2$ films on conductive $RuO_2$ and $La_{0.5}Sr_{0.5}CoO_{3}$ electrodes, respectively. Using a Kelvin probe, we measured the photovoltaic properties of these multilayer structures. A rutile-$TiO_2$ film grown on $RuO_2$ showed a very broad peak in the visible light region. An epitaxial anatase-$TiO_2$ film grown on $La_{0.5}Sr_{0.5}CoO_{3}$ showed a strong peak with a threshold energy of 3.05 eV.

• 자원환경지질
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• 제30권1호
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• pp.35-49
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• 1997

The coal formation of the Deokpyeong area are interbedded along metapelites of the Ogcheon Supergroup, which are composed mainly of graphite, quartz, muscovite and associated with small amounts of biotite, chlorite, pyrite and barite. The ratios of $SiO_2/Al_2O_3$, $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ of the coaly metapelite are variable and wide range from 1.80 to 10.21, from 27.8 to 388.8 and from 7.6 to 61.8, respectively. These coal formation were deposited in basin of marine environments, and the REE of these rocks are not influenced with metamorphism and hydrothermal alterations on the basis of $Al_2O_3$ versus La, La against Ce, the ratios of La/Ce (0.19 to 0.99) and Th/U (0.02 to 4.75). These rocks also show much variation in $La_N/Yb_N$ (1.19 to 22.89), Th/Yb (0.14 to 21.43) and La/Th (0.44 to 13.67), and their origin is explained by derivation from a mixture of sedimentary and igneous rocks. The wide range in trace and REE element characteristics as Co/Th (0.12 to 2.78), La/Sc (0.33 to 10.18), Sc/Th (0.57 to 5.73), V/Ni (8 to 2347), Cr/V (0.02 to 0.67) and Ni/Co (1.56 to 32.95) of these coaly metapelites argues for inefficient mixing of the various source lithologies during sedimentation. Deep to pale green barium-vanadium muscovites (vanadium-oellacherite) have been found in this coal formations. Modes of occurrence and grain size of muscovite are heterogeneous, but most of the barium and vanadium-bearing muscovites occur along the boundaries between graphite and quartz grains, ranging from 200 to $350{\mu}m$ in length and from 40 to $60{\mu}m$ in width. Results of X-ray diffraction data of the minerals characterized to be monoclinic system with $a=5.249{\AA}$, $b=8.939{\AA}$, $c=20.924{\AA}$ and ${\beta}=95.894^{\circ}$. Representative chemical formula of the muscovite was $(Na_{0.09}K_{1.44}Ba_{0.46})(Al_{2.75}Ti_{0.07}V_{0.56}Fe_{0.08}Mg_{0.50})(Si_{6.12}Al_{1.88})O_{22}$. The V possibly substitute octahedral Al, and the Ba is coupled substitution of $K^+Si^{4+}=Ba^{2+}Na^+Ca^{2+}$, which compositional ranges of V and Ba are from 0.42 to 0.69 and from 0.34 to 0.56 based on $O_{22}$, respectively. Formation mechanism of the barium-vanadium muscovites in the coaly metapelite is shown that the formed by high pressure and temperature from regional metamorphism origanated during diagenesis at the interface between a basinal brine and organic matter.

• 한국결정성장학회지
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• 제29권5호
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• pp.187-191
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• 2019

고체전지, 산화물연료전지, 센서, 산화물 분리막 등 에너지 재료로 활용이 무궁한 산소 이온 전도체 중 acceptor가 첨가된 $LaAlO_3$의 전기적 특성과 고온에서의 혼합전도체로 사용 가능성을 연구하였다. Sr과 Mg을 $LaAlO_3$에 동시에 첨가하여 만든 LSAM의 전기적 특성을 교류(a.c.)와 직류(d.c.) 방법을 이용하여 다양한 산소 분압에서 측정하였다. 교류 임피던스 방법을 이용하여 LSAM의 전체 저항에서 입자(grain) 저항과 입계(grain boundary) 저항을 분리한 결과, $550^{\circ}C$ 이하의 온도에서는 입계 저항이 지배적이나 $800^{\circ}C$ 이상의 온도에서는 입자 저항이 대부분임을 알 수 있었다. 또 산소분압에 따른 전도도 측정을 물질의 결함모델(defect model)을 이용하여 분석해 전체 전도도를 이온 전도도와 전자 전도도로 분리하였다. 그 결과, $800^{\circ}C$ 이상의 고온에서 LSAM은 낮은 산소분압($Po_2$ < $10^{-10}atm$)에서는 산소이온 전도체이고 높은 산소분압($Po_2$ > $10^{-5}atm$)에서는 혼합전도체의 거동을 보였다. 또 온도가 증가하여도 산소이온 전도가 주도적인 산소분압의 영역은 줄어들지 않았고 낮은 산소분압에서도 안정적인 전기적 특성을 보이는 등으로 보아, LSAM은 고온의 낮은 산소분압(T > $1500^{\circ}C$, $Po_2$ < $10^{-10}atm$) 조건에서 용강에서의 산소이온센서와 같은 산소이온체로의 사용 가능성이 높다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.511-512
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• 2008

For the $CO_2$ reforming of $CH_4$, Ni catalyst was supported on La-hexaaluminate or on $\gamma$-$Al_2O_3$. The catalytic activities of Ni/La-hexaaluminate catalysts were measured at $700^{\circ}C$ using gas chromatography (GC) for 72 h, and the reaction was maintained up to 72 hfor the investigation of catalyst deactivation. The surface of each catalyst after 72 h reaction was investigated using SEM and TEM, and the composition of the carbon deposits was investigated by using EA, TPO and TGA. Ni/La-hexaaluminate shows higher resistance to coke deposition than conventional Ni/$Al_2O_3$ which seems to be due to strong interaction between Ni and the support material. As a result of the reforming reaction, various types of carbon deposits were created on catalyst surface and the amounts of them were much smaller in the case of La-hexaaluminate than on $Al_2O_3$.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.185-188
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• 1999

Biepitaxial Y$_1Ba_2Cu_3O_{7-x}$ (YBCO) and La$_{0.2}Sr_{0.8}MnO_3$ (LSMO) thin films have been prepared on SrTiO$_3$ buffer layer and MgO seed layer grown on Al$_2O_3$(11${\bar{2}}$0)substrates by dc-sputtering with hollow cylindrical targets, respectively. We charaterized Josephson properties and significantly large magnetoresistance in YBCO and LSMO films with 45$^{\circ}$ grain boundary junction, respectively. The observed working voltage (I$_cR_n$) at 77 K in grain boundary junction was below 10${\mu}$V, which is typical I$_cR_n$ value of single biepitaxial Josephson junction. The field magnetoresistance ratio (MR) of LSMO grain boundary juncoon at 77K was enhanced to 13%, which it was significant MR value with high magnetic field sensitivity at a low field of 250 Oe. These results indicate that inserting the insulating layer instead of the grain boundary layer with metallic phase can be possible to apply a new SIS Josephson junction and a novel magnetic device using spin-polarized tunneling junction.

• 한국재료학회지
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• 제21권8호
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• pp.468-475
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• 2011

[ $LaMeO_3$ ](Me = Cr, Co) powders were prepared using the polymeric precursor method. The effects of the chelating agent and the polymeric additive on the synthesis of the $LaMeO_3$ perovskite were studied. The samples were synthesized using ethylene glycol (EG) as the solvent, acetyl acetone (AcAc) as the chelating agent, and polyvinylpyrrolidone (PVP) as the polymer additive. The thermal decomposition behavior of the precursor powder was characterized using a thermal analysis (TG-DTA). The crystallization and particle sizes of the $LaMeO_3$ powders were investigated via powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and particle size analyzer, respectively. The as-prepared precursor primarily has $LaMeO_3$ at the optimum condition, i.e. for a molar ratio of both metal-source (a : a) : EG (80a : 80a) : AcAc (8a) inclusive of 1 wt% PVP. When the as-prepared precursor was calcined at $700^{\circ}C$, only a single phase was observed to correspond with the orthorhombic structure of $LaCrO_3$ and the rhombohedral structure of $LaCoO_3$. A solid-electrolyte impedance-metric sensor device composed of $Li_{1.5}Al_{0.5}Ti_{1.5}(PO_4)_3$ as a transducer and $LaMeO_3$ as a receptor has been systematically investigated for the detection of NOx in the range of 20 to 250 ppm at $400^{\circ}C$. The sensor responses were able to divide the component between resistance and capacitance. The impedance-metric sensor for the NO showed higher sensitivity compared with $NO_2$. The responses of the impedance-metric sensor device showed dependence on each value of the NOx concentration.

• 한국세라믹학회지
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• 제45권3호
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• pp.157-160
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• 2008

A series of $La_2O_3$-added zincborosilicate glasses was fabricated by systematically varying $La_2O_3$ addition up to 15mol% under the constraint of a ZnO:$B_2O_3$ ratio of 1:2. The degree of water leaching after ball milling of the prepared glasses in water medium was relatively quantified by the change in zinc peak intensity in energy dispersive spectroscopy. 8mol% of $La_2O_3$ was the most efficient addition in inhibiting the glass leaching by water. The role of $La_2O_3$ in inhibiting the leaching was explained in terms of change of structural units in the glass network. When the optimum 8mol% $La_2O_3$-added ZnO-$B_2O_3$ glass was used as sintering aid for $Al_2O_3$, the fabricated alumina-glass composite at $875^{\circ}C$ demonstrated dielectric constant of 6.11 and quality factor of 15470 GHz, indicating the potential of leaching-minimized $La_2O_3-ZnO-B_2O_3$ glass for application to low temperature co-firing ceramic technology.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2007년도 추계학술발표대회 및
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• pp.22.2-22.2
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• 2007

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.47.1-47.1
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• 2008

• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.657-660
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• 2009

The surface of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ cathode particle was modified by lanthanum based oxide to improve electrochemical property and thermal stability. The XRD pattern of surface layer was indexed with that of $La_4NiLiO_8$. The discharge capacity of modified electrode was higher than that of pristine sample, specially at fast charge-discharge rate and high cut-off voltage. In the DSC profile of the charged sample, the generation of heat by exothermic reaction was decreased by surface modification. Such enhancement may by attributed to the presence of stable lanthanum based oxide, which effectively suppressd the reaction between electrode and electrolyte on the surface of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ electrode.