• Journal of the Korean Ceramic Society
• /
• v.42 no.7 s.278
• /
• pp.509-515
• /
• 2005

Interfacial reactions at LSGM electrolyte and NiO-GDC anode interfaces were thoroughly investigated with Environmental Scanning Electron Microscopy (ESEM-PHlLIPS XL-30) and Energy Dispersive X-ray (EDX-Link XL30). According to the analysis, serious reaction zone was observed at LSGM/NiO-GDC interface. It was found that the reaction layer was originated from the chemical reaction between NiO and LSGM. The reaction products were identified as La deficient form of LSGM based perovskite and Ni-La-O compounds such as LaSrGa$_{3}$O$_{7}$ and LaNiO$_{3}$ from the X-Ray Diffraction (XRD, Philips) analysis. According to the electrical characterization, interfacial layer was very electrically resistive which would be the cause of high internal resistance and low power generating characteristic of the unit cell.

• Advances in nano research
• /
• v.3 no.2
• /
• pp.81-96
• /
• 2015

Octahedral shaped single crystalline undoped and Ga-doped indium oxide nano-and microcrystals were fabricated using vapor-solid growth process. Effects of Ga doping on the crystallinity, defect structure, and optical properties of the nano-/microstructures have been studied using scanning electron microscopy, microRaman spectroscopy, transmission electron microscopy and cathodoluminescence spectroscopy. It has been observed that incorporation of Ga does not affect the morphology of $In_2O_3$ structures due to its smaller ionic radius, and similar oxidation state as that of In. However, incorporation of Ga in high concentration (~3.31 atom %) causes lattice compression, reduces optical band gap and defect induced CL emissions of $In_2O_3$ nano-/microcrystals. The single crystalline Ga-doped, $In_2O_3$ nano-/microcrystals with low defect contents are promising for optoelectronic applications.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.6
• /
• pp.547-552
• /
• 1999

Langasite$(La_{3}Ga_{5}SiO_{14})$ single crystal was successfully grown by Floating Zone (FZ) method and characterized. The growth rate was 1.5 mm/h and the rotation speed was 15 rpm for an upper rotation and 13 rpm for a lower rotation. The grown crystal was 12 mm in length and 6 mm in diameter. The grown crystal was dark orange color and it was grown along [001] direction. The composition of grown crystal and the structure were analyzed using XRD and WDS. The electrical properties of grown crystal at various frequencies and temperatures were discussed.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.02a
• /
• pp.56-56
• /
• 1999

• ETRI Journal
• /
• v.18 no.4
• /
• pp.339-346
• /
• 1997

Good quality a-axis oriented thin films of $YBa_2Cu_3O_{7-x}$ may be grown by the use of a $PrBa_2Cu_3O_{7-x}$ (PBCO) layer as a template. Here we present a detailed study of the nucleation of the PBCO layer, explaining the orientations observed. It is determined that the wavy surface of a $LaSrGaO_4$ (LSGO) (100) substrate consists of the {101} planes by observing cross-sectional transmission electron microscopy images of the interface between the PBCO film and the substrate. The images and selected area diffraction patterns show that a mixed c-and b-axis oriented PBCO layer was initially grown on the substrate, followed by pure b-axis oriented PBCO growth. We explain that the c-axis oriented growth is the result of the growth of the PBCO (019) planes on the LSGO (101) planes. We conclude that the nucleation and growth of the PBCO films at the initial stages depends on the crystallographic plane of the substrate surfaces, however, as the film grows further, the kinetics of the deposition process favors b-axis oriented growth.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.12 no.2
• /
• pp.63-67
• /
• 2002

Langasite single crystal was grown by Xenon-arc floating zone method in mixutre of Af and $O_2$ gas atmosphere. Growing and rotation speed were 1.5 much and 15 rPm respectively. The grown crystal had a c-axis and color of orange. Composition of the grown crystal was $La_{3.10}Ga_{4.73}Si_{1.17}O_{14}$. Activation energy of the crystal was 0.23 eV and was PTC characteristics.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.5
• /
• pp.475-479
• /
• 1999

Langasite ($La_{3}Ga_{5}SiO_{14}$) was found to have wide application as a promising piezoelectric material. It has high thermal stability of the frequency and large electromechanical coupling factor. For the further development of new compounds with langasite type structure, powders in the La-Al-Si-O system were synthesized by a modified Pechini process. The evolution of the crystalline phase during calcination was studied using TG-DTA, XRD and TEM for the precursor powders. Decomposition proceeded via dehydration and removal of excess solvents at low temperatures ($T<500^{\circ}C$), followed by the crystallization of lanthanum aluminum silicate ($T>800^{\circ}C$) and phase transformation to $LaAlO_{3}$ phase ($T>1200^{\circ}C$). Transmission electron microscopy (TEM) of the calcined powders showed diffuse hollow rings corresponding to an amorphous phase at $800^{\circ}C$ and clear diffraction patterns corresponding to a crystalline phase from the P321 space group ($T<1200^{\circ}C$) and the R3m ($T<1200^{\circ}C$).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.191-194
• /
• 2004

Ferroelectric $Pb(Zr_{0.52}Ti_{0.48})O_3$ (PZT) 박막을 $Pt(111)/Ti/SiO_2/Si$ 기판위에 증착되었고, 수소 후열처리 후의 특성변화를 연구하였다. 동시에 10 nm의 $(Pb_{0.72}La_{0.28})Ti_{0.94}O_3$ (PLT) buffer를 사용한 PZT 박막의 수소 후열처리 효과를 관찰하였다. PZT 박막의 경우, 수소 후열처리 전과 후에 강유전 특성이 현저하게 감소한 반면, PLT buffer가 사용된 PZT 박막의 경우, 강유전 특성에 거의 변화가 없었다. 이는 PLT buffer를 사용함으로써 PZT 박막의 배향성이 향상되고, 이에 따라 forming gas에 의한 수소원자가 박막 내로의 침투가 어렵게 된다. 따라서 수소원자에 대한 PZT 박막의 열화되는 현상이 buffer를 사용하는 경우, 거의 나타나지 않게 된다.

• Journal of the Korean Ceramic Society
• /
• v.44 no.12
• /
• pp.715-719
• /
• 2007

STS444 with or without $La_{0.9}Sr_{0.1}MnO_3$ (LSM)-coating was contacted to $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3$ (LSCF) cathode on various electrolyte materials and the polarization resistance $(R_p)$ was measured by impedance spectroscopy. By making a symmetric half-cell and contacting only one side of the cathode with the interconnect, the effect of chromium (Cr) poisoning was separated from the aging effects. When the LSCF cathode was contacted with LSM-coated STS (stainless steel), $R_p$ of LSCF was lower than that contacted with the uncoated STS. Impedance patterns measured for the working electrode (W.E.), the counter electrode (C.E.) at $600^{\circ}C$ in air were analyzed. Normalized data of net Cr effect showed that $Ce_{0.9}Gd_{0.1}O_2$ (GDC) electrolyte is more tolerant to the chromium poisoning than $La_{0.9}Sr_{0.1}Ga_{0.8}Mg_{0.2}$ (LSGM) or 8 mol% $Y_2O_3-doped$ $ZrO_2$ (YSZ) electrolytes.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1998.06a
• /
• pp.105-109
• /
• 1998

Langasite({{{{ { La}_{ 3} {Ga }_{5 } {SiO }_{14 } , LGS}}}}) powder was prepared by a polymerized complex method based on the Pechini-type reaction. A mixed solution of ethylene glycol(EG), cotric acid(CA), lanthanum, gallium and silicon ions, with a molar ratio of EG:CA:La:Ga:Si=100:25:3:5:1, was polymerzed to from a transparent resin, which was used as a precursor for the synthesis of LGS. X-ray diffraction(XRD) patterns indicated that the LGS phase could be formed by the heat-treatment in air at 1000$^{\circ}C$ for 3hrs