• Journal of the Korean Ceramic Society
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• v.28 no.2
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• pp.101-108
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• 1991

0.2 mo1% La doped BaTiO3 samples were prepared by a wet chemical process (Pechini process) and electrical conductivity were measured from annealing temperatures(800-110$0^{\circ}C$) to room temperature continuously. 2 probe I-V characteristics showed that Pt electrodes were non-ohmic below about 80$0^{\circ}C$ for Ladoped sample. I-V curves showed varistor behavior and breakdown voltages showed PTC-like behavior. AC complex impedance of 0.2 La and 0.05 Mn mo1% doped BaTiO3 samples with three different electrodes (electroless Ni, Pt, Ag electrodes) were measured with temperature variation. Complex impedance plots showed that the samples with electroless Ni electrodes have negligible electrode resistance. Samples with Ag or Pt paste electrodes showed large electrode resistance. PTC effect, which is defined as the ratio of maximum resistance to minimum resistance, was found to be less than 10 for 0.2 mo1% La doped dense sample however greater than 105 with codoping of 0.05 mo1% Mn and 0.2 mol% La.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.77-82
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• 2011

The surface of $Li[Ni_{0.35}Co_{0.3}Mn_{0.35}]O_2$ cathode was modified by $[Li,La]TiO_3$ coating using pH controlled coating solution. At low pH values (acidic solution), cathode powders, which is oxides, have a positive surface charge, whereas, they have a negative surface charge at high pH values. As a result, their charge could affect the formation of the coating layer on the surface of cathode powder. To determine the optimal pH value, the surface coating of the pristine powder was carried out at various pH values of the coating solution. The surface morphology of coated samples was characterization by SEM and TEM analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the pH of coating solution.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.434-440
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• 2003

The powders of L $a_{0.8}$C $a_{0.2}$Mn $O_3$ Colossal Magnetoresistance (CMR) materials were synthesized by sol-gel process. Lanthanum(H), Calcium(II) and Manganese(III) 2,4-Pentanedionate were dissolved in a mixed binary solution consisted of propionic acid and methanol with PEG (15 wt%) aqueous solution. The progress of reactions was monitored by FT-IR spectroscopy. The Lao scao.2Mn03 gel powders were annealed at various temperatures. The structural changes were investigated by FT-IR, CP/MAS $^{ 13}$C solid state NMR spectroscopy and XRD. The thermochemical property, particle characterization, microstructure of sintered sample, and cation composition of gel powder were studied by TG/DTA, FE-SEM and ICP-AES. The magnetic characterizations were identified through measurement of magnetic moment by VSM.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.2
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• pp.78-83
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• 2012

The structural change and the electrical conductivity with Sr content in $La_{1-x}Sr_xMn_{0.8}Cu_{0.2}O_3$ (LSMCu) were studied. $La_{0.8}Sr_{0.2}MnO_3$ (LSM) and $La_{1-x}Sr_xMn_{0.8}Cu_{0.2}O_3$ ($0.1{\leq}x{\leq}0.4$) were synthesized by EDTA citric complexing process (ECCP). A decrease in the lattice parameters and lattice volumes was observed with increase of Sr content, and these results were attributed to the increasing $Mn^{4+}$ ions and $Cu^{3+}$ ions in B-site. The electrical conductivity measured from $500^{\circ}C$ to $1000^{\circ}C$ was increased with increase of Sr content in the $0.1{\leq}x{\leq}0.3$ composition range, and it was 172.6 S/cm (at $750^{\circ}C$) and 177.7 S/cm (at $950^{\circ}C$, the maximum value) in x = 0.3. The electrical conductivity was decreased in x = 0.4 because of the presence of the second phase in the grain boundaries. The lattice volume was contracted by increase of $Mn^{4+}$ ions and $Cu^{3+}$ ions in B-site according to increase of Sr content and the electrical conductivity was increased with increase of charge carriers which were involved in the hopping mechanism.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.5
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• pp.499-503
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• 2022

La_0.7Sr_0.3MnO₃ precursor solution were prepared by a sol-gel method. La_0.7Sr_0.3MnO₃ thin films were fabricated by a spin-coating method on a Pt/Ti/SiO₂/Si substrate. Structural and electrical properties with the variation of sintering temperature were measured. All specimens exhibited a polycrystalline orthorhombic crystal structure, and the average thickness of the specimens coated 6 times decreased from about 427 nm to 383 nm as the sintering temperature increased from 740℃ to 830℃. Electrical resistance decreased as the sintering temperature increased. In the La_0.7Sr_0.3MnO₃ thin films sintered at 830℃, electrical resistivity, TCR, B-value, and activation energy were 0.0374 mΩ·cm, 0.316%/℃, 296 K and 0.023 eV, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.249-254
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• 2023

La_0.7-xCe_xSr_0.3MnO₃ specimens were fabricated by a solid state reaction method and structural and electrical properties with variation of Ce⁴⁺ contents were measured. All specimens exhibited a polycrystalline rhombohedral crystal structure, and the (110) peaks were shifted to low angle side with increasing the amount of Ce⁴⁺ contents. As Ce⁴⁺ ions with different ion radii and charges are substituted with La³⁺ ions, electrical properties are thought to be affected by changes in the double exchange interaction between Mn³⁺-Mn⁴⁺ ions due to distortion of the unit lattice, a decrease in oxygen vacancy concentration, and an increase in lattice defects. Resistivity gradually decrease as the amount of Ce⁴⁺ added increased, and negative temperature coefficient of resistance (NTCR) properties were shown in all specimens. In the La_0.5Ce_0.2Sr_0.3MnO₃ specimens, electrical resistivity, TCR and B-value were 31.8 Ω-cm, 0.55%/℃ and 605 K, respectively.

• Journal of the Korean Ceramic Society
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• v.35 no.9
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• pp.917-922
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• 1998

The polarization characteristics of the cathodes were discussed which were composed YSZ and ${(La_{0.75 }Sr_{0.25 })}_{0.95}Mn_{0.8 }Co_{0.2}O_3$ The three-phase-boundary length increased with the addition of YSN resulting in the minimum po-larization resistance at 60(LSMC) : 40(YSZ) wt% When LSMC-YSZ compoiste cathodes was sintered at $1200^{\circ}C$ minimum polarization resistance was observed and the capacitace increased with increasing sintering tem-perature.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.200-205
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• 1999

In the ferromagnetic phase with electrons for La$_{1-x}$(Ca or Sr)$_x$MnO$_3$, films, a remnant resistivity of the order of 10$^{-8}$ ${\omega}$m is observed up to 100 K and increases exponentially with temperature up to T$_c$ and above one Tesla as a function of magnetic field strength (a positive magnetoresistivity). The phase below T$_c$ is regarded as a polaronic state with a polaronic tunneling conduction. Possible p-wave condensation (or superconductor) with a parabolic density of states and the phase separation are discussed on the basis of the two-fold degeneracy of ${\varrho}_{\delta}$ orbitals.

• Korean Journal of Materials Research
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• v.18 no.4
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• pp.175-180
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• 2008

In this study, the thermoelectric power and resistivity of the perovskite manganite $La_{0.75}Ba_{0.25}MnO_3$ were investigated in the temperature range 300K-1200K. The electrical resistivity and thermoelectric power indicate a transport mechanism dominated by adiabatic small-polaron hopping. The power factor increases from $2{\times}10^{-6}W/mK^2$ to $1{\times}10^{-5}W/mK^2$ as to the temperature increases from 400K to 1200K, which indicates that the compound is highly feasible as a thermoelectric material at high temperatures.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.429-430
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• 2000