• 자연과학논문집
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• 제14권2호
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• pp.41-54
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• 2004

$LaMnO_3$(a=$5.51\AA$, c=$13.33\AA$) 페로브스카이트형 복합산화물에서 A site인 La자리에 Sr을 치환시킨 $La_{0.9}Sr_{0.1}MnO_3$(a=$5.33\AA$, c=$13.27\AA$)와 B site인 Mn을 Cu로 치환시킨 $LaMn_{0.9}Cu_{0.1}O_3$(a=$5.52\AA$, c=$13.31\AA$) 복합산화물을 Citrate sol-gel법을 이용하여 합성하였으며 분말 X-ray회절 분석기(XRD)을 이용하여 Rhombohedral의 페로브스카이트 구조임을 확인하였다. 수소 환원분위기에서의 TRR결과에 의하면 이들 산화물의 산소 화학양론은 $LaMnO_{3.16}$, $La_{0.9}Sr_{0.1}MnO_{3.10}$, $LaMn_{0.9}Cu_{0.1}O_{3.14}$의 조성을 갖는다. $LaMnO_3$는 2단계 환원반응을 일으키지만 각 자리를 치환시킨 $LaMnO_3$ 복합산화물은 3단계 환원반응을 일으켰다.

• 한국세라믹학회지
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• 제37권6호
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• pp.612-616
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• 2000

The effect of Co dopant on the (La, Sr)MnO3 cathode was investigated. La2Zr2O7 and SrZrO3 were formed as the reaction products between YSZ and LSMC. The reactivity of LSMC with YSZ increased with increasing Co content. However, the cathodic polarization resistance decreased with increasing Co doping. Therefore, doping Co at Mn site in the (La, Sr)MnO3 cathode was effective on controlling the polarization resistance of the cathode. The polarization property of LSMC-YSZ composite(60 wt%: 40 wt%) cathode was better than that of LSMC single cathode.

• 한국세라믹학회지
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• 제29권11호
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• pp.900-904
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• 1992

High temperature electrical conductivity was measured for perovskite La0.98Sr0.02MnO3 at 200~130$0^{\circ}C$ as a function of Po2 and 1/T. Perovskite La1-xSrxMnO3 system is the typical oxygen electrode in solid oxide fuel cell (SOFC). Acetate precursors were used for the preparation of mixed water solution and the calcined powders were reacted with Na2CO3 flux in order to obtain highly reactive powders of perovskite La0.98Sr0.02MnO3. The relative density was greatly increased above 90% because of the homogeneous sintering. From the conductivity ($\sigma$)-temperature and conductivity-Po2 at constant temperature, the defect structure of La0.98Sr0.02MnO3 was discussed. From the slope of 1n($\sigma$) vs 1/T, the activation energy of 0.069 and 0.108eV were evaluated for above 40$0^{\circ}C$, respectively. From the relationship between $\sigma$ and Po2, it was found that the decomposition of La0.98Sr0.02MnO3 was occurred at 10-15.5 atm(97$0^{\circ}C$) and 10-11 atm(125$0^{\circ}C$). It is supposed that the improvement of p-type conductivity may be leaded by the increase of Mn4+ concentration through the substitution of divalent/monovalent cations for La site in LaMnO3.

• 한국분말재료학회지
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• 제8권3호
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• pp.201-206
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• 2001

$>LaMnO_3$$(La, Sr)MO_3$, and $(La, Sr)MO_3/YSZ$ gel films were deposited by spin-coating technique on scandium-doped zirconia (YSZ) substrate using the precursor solution prepared from $La(O-i-C_3H_7)_3$, $Co(CH_3COO)_2$or $Mn(O-i-C_3H_7)_2$,2-methoxyethanol, and polyethylene glycol. By heat-treating the gel films, the electrochemical cells, $(La, Sr)MnO_3{\mid}ScSZ{\mid}Pt$ were fabricated. The effect of polyethylene glycol on the microstructure evolution of $$LaCoO_3and $LaMnO_3$thin films was investigated, and NOx decomposition characteristics of the electrochemical cells were investigated at $500^{\circ}C$ to $600^{\circ}C$. By applying a direct current to the $(La, Sr)MnO_3{\mid}ScSZ{\mid}Pt$ electrochemical cell, good NOx conversion rate could be obtained relatively at low current value even if excess oxygen is included in the reaction gas mixture.

• 한국세라믹학회지
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• 제44권1호
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• pp.52-57
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• 2007

We synthesized $(La_{1-x}Sr_x)MnO_3$ as a cathode for SOFC by glycine nitrate process (GNP) and knew the different properties of $(La_{1-x}Sr_x)MnO_3$ by using nitrate solution and oxide solution as a starting material. In case of using nitrate solution as a starting material, main crystal phase peak of $LaMnO_3$ increased as Sr content added up and a peak of $Sr_2MnO_4\;and\;La_2O_3$ was showed as a secondary phase. We added Mn excess to control a crystal phase. In this case, the electrical conductivity had a high value 210.3 S/cm at $700^{\circ}C$. On the other side, when we used oxide solution as a starting material, we found main crystal phase of $LaMnO_3$ to increase as Sr content added up and a peak of $La_2O_3$ as a secondary phase. Similary, we added Mn excess to control a crystal phase in this case. We knew $(La,Sr)MnO_3$ powder to sinter well and the electrical conductivity of the sintered body at $1200^{\circ}C$ for 4 h was 152.7 S/cm at $700^{\circ}C$. The sintered $(La,Sr)MnO_3$ powder at $1000^{\circ}C$ for 4 h got the deoxidization peak, depending on the temperature and in case of using nitrate solution as a starting material, the deoxidization peak was showed at $450^{\circ}C$ which is lower than used a oxide solution as a starting material. As a result, when $(La,Sr)MnO_3$ powder was synthesized to add Mn excess and to use nitrate solution as a starting material, we found it to have the higher deoxidization property and considered it as a cathode for SOFC properly. And we found it to have different electrical conductivity the synthesized $(La,Sr)MnO_3$ powder by using different starting materials like nitrate solution and oxide solution which influence a sintering density and crystal phase.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.360-363
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• 2006

We synthesized $(La,\;Sr)MnO_{3+{\delta}$ as a cathode for SOFC by glycine nitrate process(GNP) and knew the different properties of $(La_{1-x}Sr_x)MnO_3$ by using nitrate solution and oxide solution as starting material. In case of using nitrate solution as a starting material, main crystal phase peak of $LaMnO_3$ increased as Sr content added up and a peak of $Sr_2MnO_4\;and\;La_2O_3$ was showed as a secondary phase. We added Mn excess to control a crystal phase. In this case, the electrical conductivity had a high value 210.3S/cm at $700^{\circ}C$ On the other side, when we used oxide solution as a starting material, we found main crystal phase of $LnMnO_3$ to increase as Sr content added up and a peak of $La_2O_3$ as a secondary phase. Similary, we added Mn excess to control a crystal phase in this case. We knew $(La,\;Sr)MnO_3$ powder to sinter well and the electrical conductivity of the sintered body at $1200^{\circ}C$ for 4hrs was 152.7s/cm at $700^{\circ}C$. The sintered $(La,\;Sr)MnO_3$ powder at $1000^{\circ}C$ for 4hrs got the deoxidization peak, depending on the temperature md in case of using nitrate solution as a start ing material the deoxidization peak was showed at $450^{\circ}C$ which is lower than used a oxide solution as a starting material. As a result, when $(La,\;Sr)MnO_3$ powder was synthesized to add Mn excess and to use nitrate solution as a starting material, we found it to have the higher deoxidization property and considered it as a cathode for m properly. And we found it to have different electrical conduct ivity the synthesized $(La,\;Sr)MnO_3$ powder by using different start ing materials like nitrate solution and oxide solution which influence a sintering density and crystal phase.

• 한국세라믹학회지
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• 제35권9호
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• pp.981-987
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• 1998

$La_{0.5}Sr_{0.5}MnO_{3-\delta}$ as air electrode for soild oxide fuel cell was synthesized by a citrate process and its cathodic polarization was determinated by the current interruption method on the Gd-doped ceria as electrolyte. The addition of citric acid increased the exothermic heat for the formation of $La_{0.5}Sr_{0.5}MnO_{3-\delta}$ perovskite oxide. The degree of the initial particle agglomeration was affected by the exothermic heat. Also the increase of cal-cination temperature enlarged the particle size and the higher sintering temperature accelerated the den-sification of $La_{0.5}Sr_{0.5}MnO_{3-\delta}$ layer after its being painted on $Ce_{0.8}Gd_{0.2}O_{1.9}$ electrolyte. In this study $La_{0.5}Sr_{0.5}MnO_{3-\delta}$ synthesized by citrate process of which the molar ratio of citric acid to metal nitrate was 2 calcined at $650^{\circ}C$ for 2hr and sintered at 1100 at $1200^{\circ}C$ for 4 hrs after slurry coating on Ce0.8Gd0.2O1.9 electrlyte showed the lowest cathodic polarization.

• 한국전기전자재료학회논문지
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• 제23권4호
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• pp.303-310
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• 2010

We fabricated $La_{0.6}Sr_{0.4}MnO_3$ thin films using radio frequency (RF) magnetron sputtering. They were grown on sapphire substrates with various deposition conditions. After the growth of the $La_{0.6}Sr_{0.4}MnO_3$ thin films, they were annealed at various temperatures to be crystallized. We successfully fabricated single phase $La_{0.6}Sr_{0.4}MnO_3$ thin films with high electrical conductivity. The room temperature resistivity was $1.5{\times}10^{-2}{\Omega}{\cdot}cm$. It can be considered that $La_{0.6}Sr_{0.4}MnO_3$ thin films are one of the feasible candidates for electrodes for integrated device applications.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.271-274
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• 1998

Metallic ferromagnet LA$_{1-x}$ Sr$_{x}$MnO$_3$ has received considerable attentions because of its metallic conductivity and giant magnetic resistivity. It is generally believed that layered perovskite SrO(LA$_{1-x}$ Sr$_{x}$MnO$_3$)$_{n}$ phase is insulating and shows no metallic transition. But recent report revealed that some single crystal SrO(LA$_{1-x}$ Sr$_{x}$MnO$_3$)$_{n}$ phase showed MR effect. In this study, layered perovskite SrO(LA$_{1-x}$ Sr$_{x}$MnO$_3$)$_2$ Phases were synthesized by solid state reaction at 140$0^{\circ}C$ in air atmosphere, for wide range of x and their phases were confirmed by X-ray diffraction. Electrical and magnetic properties were measured down to 10K and the possibility of MR effects was investigated.as investigated.

• 한국재료학회지
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• 제10권6호
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• pp.437-444
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• 2000

기판온도, 박막조성 및 증착후 열처리 등의 조건에 따른 ${La_{1-x}}{Sr_x}{MnO_{3-{\delta}}}$(0.19$\leq$x$\leq$0.31) 박막의 결절구조와 전기전도 특성을 조사하였다. 스퍼터법을 이용하여 $500^{\circ}C$에서 증착된 박막은 강한 <001> 우선배향성과 유사정방정(pseudo-tetrag-onal, a/c-=0.97) 결정체를 나타냈다. 이러한 박막의 단위포는 산소분위기 내에서 증착후 열처리에 의하여 입장정 결정계로 변하였다. $La_{0.67}Sr_{0.33}MnO_3$ 조성의 주타겟과 $La_{0.3}Sr_{0.7}MnO_3$조성의 보조타겟을 동시에 이용하여 박막의 조성을 조절하였다. 보조타겟의 개수에 따라 박막내의 Sr 함량(x)은 0.19-0.31 범위의 값을 나타내었으며, x값이 0.19로부터 0.31로 증가시 금소-반도체의 전이 온도가 상승하였고, 전지비저항이 대체로 감소하였다. 0.18 T의 자기장 하에서, $La_{0.69}Sr_{0.31}MnO_3$조성의 박막의 자기저항변화 MR((%) = (${\rho}_o-{\rho}_H/{\rho}_H$)는 약 390% 이었다.