• Journal of the Korean Ceramic Society
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• v.51 no.1
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• pp.51-56
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• 2014

Mixed ionic and electronic conducting $K_2NiF_4$-type oxide, $Nd_{2-x}Sr_xNiO_{4+\delta}$ (x = 0, 0.4, 0.6) powders were synthesized by a solid-state reaction technique and solid oxide fuel cells consisting of a $Nd_{2-x}Sr_xNiO_{4+\delta}-GDC$ cathode, a Ni-YSZ anode and 8YSZ as an electrolyte were fabricated. The effect of strontium substitution for neodymium on the electrical and electrochemical properties was examined. The electrical conductivity increased with an increase in the Sr doping content, while it appears that the excess oxygen (${\delta}$) decreased. Sr doping into $Nd_2NiO_{4+\delta}$ resulted in an increase in the cathode polarization resistance and an decrease in the power density of the cell. These phenomena may be associated with the decreased amount of excess oxygen noted in the $Nd_{2-x}Sr_xNiO_{4+\delta}$ cathode.

• Proceedings of the Materials Research Society of Korea Conference
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• 1993.11a
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• pp.18-18
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• 1993

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.4-4
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• 2002

• Progress in Superconductivity and Cryogenics
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• v.16 no.2
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• pp.36-41
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• 2014

Temperature dependence of magnetic moment (m-T) and the magnetization (M-H) at 5 K and 20 K of the in situ processed $MgB_2$ bulk pellets with/without carbon (C) doping were examined. The superconducting critical temperature ($T_c$), the superconducting transition width (${\delta}T$) and the critical current density ($J_c$) were estimated for ten test samples taken from the $MgB_2$ bulk pellets. The reliable m-T characteristics associated with the uniform $MgB_2$ formation were obtained for both $MgB_2$ pellets. The $T_cs$ and ${\delta}Ts$ of all test samples of the undoped $MgB_2$ were the same each other as 37.5 K and 1.5 K, respectively. The $T_cs$ and ${\delta}Ts$ of the C-doped $MgB_2$ were 36.5 K and 2.5 K, respectively. Unlike the m-T characteristics, there existed the difference among the M-H curves of the test samples, which might be caused by the microstructure variation. In spite of the slight $T_c$ decrease, the C doping was effective in enhancing the $J_c$ at 5 K.

• Korean Journal of Materials Research
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• v.29 no.10
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• pp.586-591
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• 2019

This study describes the doping effect of $Yb_2O_3$ on microstructure, electrical and dielectric properties of $ZnO-V_2O_5-MnO_2-Nb_2O_5$ (ZVMN) ceramic semiconductors sintered at a temperature as low as $900^{\circ}C$. As the doping content of $Yb_2O_3$ increases, the ceramic density slightly increases from 5.50 to $5.54g/cm^3$; also, the average ZnO grain size is in the range of $5.3-5.6{\mu}m$. The switching voltage increases from 4,874 to 5,494 V/cm when the doping content of $Yb_2O_3$ is less than 0.1 mol%, whereas further doping decreases this value. The ZVMN ceramic semiconductors doped with 0.1 mol% $Yb_2O_3$ reveal an excellent nonohmic coefficient as high as 70. The donor density of ZnO gain increases in the range of $2.46-7.41{\times}10^{17}cm^{-3}$ with increasing doping content of $Yb_2O_3$ and the potential barrier height and surface state density at the grain boundaries exhibits a maximum value (1.25 eV) at 0.1 mol%. The dielectric constant (at 1 kHz) decreases from 592.7 to 501.4 until the doping content of $Yb_2O_3$ reaches 0.1 mol%, whereas further doping increases it. The value of $tan{\delta}$ increases from 0.209 to 0.268 with the doping content of $Yb_2O_3$.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.280-284
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• 2016

본 연구에서는 Density functional theory(DFT) 계산을 이용하여, $MoS_2$의 Mo와 S를 다른 원자로 치환 했을 때 $2H-MoS_2$ monolayer의 basal plane에서 HER활성을 향상시켰다. 특히 Ge와 Rh를 치환한 경우, ${\Delta}G_H$가 각각 0.03eV, 0,07eV로 최적에 가까운 HER활성이 나타났다. 다른 원자의 치환이 Fermi level 근처의 DOS(density of states)를 높여, ${\Delta}G_H$을 0에 가깝게 낮출 수 있음을 확인하였다. 또한 치환되는 원자의 농도, 그리고 strain을 변화시켜 농도와 strain의 증가에 따른 ${\Delta}G_H$ 감소를 발견했다. 이로써 각치환되는 원자마다, 치환 농도와 strain을 함께 변화시켜 ${\Delta}G_H$을 낮출 수 있었다. ${\Delta}G_H$가 0에 가까운(${\pm}{\pm}0.2eV$ 이내) 원자종류, 치환 농도, strain의 여러 조합을 찾았다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.2
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• pp.113-117
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• 2007

We have investigated the effects of doping concentration in polysilicon floating gate on the endurance characteristics of the EEPROM cell haying the structure of spacer select transistor. Several samples were prepared with different implantation conditions of phosphorus for the floating gate. Results show the dependence of doping concentration in polysilicon floating gate on performance of EEPROM cell from the floating gate engineering point of view. All of the samples were endured up to half million programming/erasing cycle. However, the best $program-{\Delta}V_{T}$ characteristic was obtained in the cell doped at the dose of $1{\times}10^{15}/cm^{2}$.

• Korean Journal of Materials Research
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• v.16 no.7
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• pp.412-415
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• 2006

Te-doped $CoSb_3$ was prepared by the encapsulated induction melting, and its doping effects on the thermoelectric properties were investigated. Single phase ${\delta}-CoSb_3$ was successfully obtained by the subsequent annealing at 773 K for 24 hrs. Tellurium atoms acted as electron donors by substituting antimony atoms. Thermoelectric properties were remarkably improved by the appropriate doping. Dimensionless figure of merit was obtained to be 0.83 at 700K for the $CoSb_{2.8}Te_{0.2}$ specimen.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1241-1242
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• 2006

Electromagnetic properties of $CeO_2$ doped and undoped YBaCuO superconductors were evaluated to investigate the effect of pinning center on the magnetization and magnetic shielding. The variation $\DeltaM$ with doping was maximum for 3% doping and decrease with further doping. The magnetic shielding was evaluated by measuring the induced voltage in secondary coil and the voltage initially set to 0.5V, decreased to 0.17V and 0.28V respectively for the undoped and 3% $CeO_2$ doped sample. The much less change in the induced voltage for the 3% doped sample is attributed to the increased flux shielding by shielding vortex current. The $CeO_2$ was converted to fine $BaCeO_3$ particles which were trapped in YBaCuO superconductor during the reaction sintering. The trapped fine particles, $BaCeO_3$ may be acted as a flux pinning center.

• Korean Journal of Materials Research
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• v.16 no.6
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• pp.382-385
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• 2006

Ni-doped $CoSb_3$ was prepared by the hot pressing, and its doping effects on the thermoelectric properties were investigated. Single phase ${\delta}-CoSb_3$ was successfully obtained by encapsulated induction melting and the subsequent heat treatment at 773 K for 24 hrs, followed by the hot pressing under 60 MPa at 773 K for 2 hrs. Nickel atoms acted as electron donors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by the Ni doping.