• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.124-128
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• 2000

Electrical properties of $ZrO_2-TiO_2Yb_2O_3$mixed conductor (Ti-YbSZ) were investigated. This mixed conductor can be applied as a membrane for gas separation at high temperatures. The total conductivity decreased with increasing the $TiO_2$concentration. At high temperatures, the rate of the conductivity degradation became smaller than that at low temperatures. From the oxygen partial pressure dependence of the total conductivity of Ti-YbSZ, the electronic conductivity increased with increasing $TiO_2$concentration at low oxygen partial pressures and at high temperatures. Both 15 and 20 mol% $TiO_2$doped YbSZ showed high oxygen permeability. Mixed conductors, which has high $TiO_2$concentration in YbSZ, are promising materials for using as a membrane for gas separation at high temperatures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.12
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• pp.1082-1086
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• 2007

Optical characteristics of $YCOB(YCa_4B_3O_{10})$, known as a crystal of self frequency doubling, was investigated when Yb and Er ions were co-doped 20 % and 2 %, respectively. The absorption cross section of Er,Yb:YCOB crystal at $1.0\;{\mu}m$ was larger than that of Yb:YCOB, which means that the former was profitable for more energy absorption than the latter. The fluorescent lifetime at $1.5\;{\mu}m$ was measured to be 1.27 ms at room temperature, and lengthened to 1.54 ms and 1.62 ms at low temperatures of 77 K and 6 K, respectively. The line widths of fluorescent spectrum at $1.5\;{\mu}m$ were getting narrower as lowering temperature. However, we didn't observe a temperature dependent peak wavelength shift.

• Korean Journal of Materials Research
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• v.25 no.9
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• pp.480-486
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• 2015

$Pb_{1-x}MoO_4:Er^{3+}/Yb^{3+}$ phosphors with various doping concentrations of $Er^{3+}$ and $Yb^{3+}$ ($x=Er^{3+}+Yb^{3+}$, $Er^{3+}=0.05$, 0.1, 0.2, and $Yb^{3+}=0.2$, 0.45) are successfully synthesized using a microwave sol-gel method, and the up-conversion photoluminescence properties are investigated. Well-crystallized particles, which are formed after heat treatment at $900^{\circ}C$ for 16 h, exhibit a fine and homogeneous morphology with particle sizes of $2-5{\mu}m$. Under excitation at 980 nm, the $Pb_{0.7}MoO_4:Er_{0.1}Yb_{0.2}$ and $Pb_{0.5}MoO_4:Er_{0.05}Yb_{0.45}$ particles exhibit a strong 525 nm emission band, a weak 550 nm emission band in the green region, and a very weak 655 nm emission band in the red region. The Raman spectra of the doped particles indicate the presence of strong peaks at higher and lower frequencies induced by the disordered structures of $Pb_{1-x}MoO_4$ through the incorporation of the $Er^{3+}$ and $Yb^{3+}$ ions into the crystal lattice, which results in the unit cell shrinkage accompanying the new phase formation of the $MoO_{4-x}$ group.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.514-520
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• 2015

$KY_{1-x}(WO_4)_2:Ho^{3+}/Yb^{3+}$ yellow phosphors with doping concentrations of $Ho^{3+}$ and $Yb^{3+}$ ($x=Ho^{3+}+Yb^{3+}$, $Ho^{3+}=0.05$, 0.1, 0.2 and $Yb^{3+}=0.2$, 0.45) were successfully prepared using the microwave-modified sol-gel method; their upconversion (UC) photoluminescence properties were investigated in detail. Well-crystallized particles, formed after heat-treatment at $900^{\circ}C$ for 16 h, showed a fine and homogeneous morphology with particle sizes of $2-5{\mu}m$. Under excitation at 980 nm, the UC $KY_{0.7}(WO_4)_2:Ho_{0.1}Yb_{0.2}$ and $KY_{0.5}(WO_4)_2Ho_{0.05}Yb_{0.45}$ particles exhibited excellent yellow emissions based on a strong 545-nm emission band in the green region and a very strong 655-nm emission band in the red region. Pump power dependence and Commission Internationale de L'Eclairage chromaticity of the UC emission intensity were evaluated. The spectroscopic properties were examined comparatively using Raman spectroscopy.

• 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 $Yb_2O_3$.

• Journal of the Korean Ceramic Society
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• v.35 no.1
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• pp.79-87
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• 1998

Melt spun YbBa2Cu3Agx(x=0, 5, 12, 16 and 53) precursor alloy ribbons were oxidized at 263-330$^{\circ}C$ and treated at 820$^{\circ}C$, 855$^{\circ}C$ and 885$^{\circ}C$ under 1.0 atm oxygen pressure. In the ribbons treated at 820$^{\circ}C$, 855$^{\circ}C$and 885$^{\circ}C$ 1-2-4 phase (YbBa2Cu4O8) and 1-2-3 phase (YbBa2Cu3O{{{{ OMICRON _7-$\delta$ }})were formed respectively. The shape of 1-2-4 phase was distorted or ellipsoid. The 2-4-7 and 1-2-3 phases tooked the shape of bar. All the ribbons showed zero critical current density Jc at 77K in zero magnetic field. By considering the shape and the highest critical temperature (among the three phases) of the 1-2-3 phase we tried to increase the critical current density of the ribbons treated at 885$^{\circ}C$ by press deformation. About tenribbons were stacked and coupled by press deformation and then treated at 885$^{\circ}C$ These 1-2-3 phase did not show any texture in any of the ribbons. However they exhibited weak texture in the multilayered specimens. Among the multilayered specimens YbBa2Cu3Ag16 exhibited a Jc of 180 A/cm2 Among the above ribbons YbBa2Cu3Ag16 ribbon has the optimum composition to produce textured superconducting oxide with improved Jc by press deformation. Onset critical temperatures Ton of the multilayered YbBa2Cu3Agx(x=5, 12, 16 and 53) were measured as 88-90 K.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.68-72
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• 1997

In this paper, to obtain the YbB $a_2$C $u_3$ $O_{x}$ superconductor, the mixed Powders of Y $b_2$ $O_3$, BaC $O_3$, CuO and Y $b_2$BaCu $O_{5}$, BaCu $O_2$ were used and the various calcining conditions were applied for the 123 phase of YbB $a_2$C $u_3$ $O_{x}$. Samples were prepared by the mixed oxide method and calcined with various temperatures of 88$0^{\circ}C$ ~91$0^{\circ}C$ . It was observed that the distribution of YbB $a_2$C $u_3$ $O_{x}$ phase which was calcined at 90$0^{\circ}C$ for 12 hours and 99 hours. But the result of long time calcination(99 hrs), the 123 phase of YbB $a_2$C $u_3$ $O_{x}$ was existed between 89$0^{\circ}C$ and 91$0^{\circ}C$ . And the best case could be obtained at the calcination temp. of 90$0^{\circ}C$ from the mixed Powder of YbB $a_2$C $u_3$ $O_{5}$ and Bacu $O_2$ which were prepared individually.idually.

• Current Optics and Photonics
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• v.5 no.4
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• pp.450-457
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• 2021

Upconversion (UC) properties of Y₂O₃:Ho³⁺/Yb³⁺ spherical particles synthesized by spray pyrolysis were investigated by changing the dopant concentration and calcination temperature. Citric acid (CA), ethylene glycol (EG) and N, N-dimethylformamide (DMF) were used to control the microstructure of Y₂O₃:Ho³⁺/Yb³⁺ particles. In terms of achieving the highest UC green emission intensity, the optimal concentrations of Ho³⁺ and Yb³⁺ were found to be 0.3% and 3.0%, respectively. In addition, the UC intensity of Y₂O₃:Ho³⁺/Yb³⁺ showed a linear relationship with the crystallite size. The use of organic additives allows Y₂O₃:Ho³⁺/Yb³⁺ particles to have a spherical and dense structure, resulting in significantly reducing the surface area while maintaining high crystallinity. As a result, the UC emission intensity of Y₂O₃:Ho³⁺/Yb³⁺ particles having a dense structure showed the UC emission intensity about 3.8 times higher than that of hollow particles prepared without organic additives. From those results, when Y₂O₃:Ho³⁺/Yb³⁺ particles are prepared by the spray pyrolysis process, the use of the CA/EG/DMF mixtures as organic additives has been suggested as an effective way to substantially increase the UC emission intensity.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.174-174
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• 2009

다양한 ITO타겟(doped Yb: 0, 0.57, 3.2 and 7.75at%)을 사용하여, DC 마그네트론 스퍼터링에 의해 폴리이미드 기판위에 증착한 ITO:Yb박막의 구조적, 전기적, 기계적 특성을 연구하였다. 증착된 박막내의 Yb 함량이 증가됨에 따라, 박막의 결정성이 감소되고, 표면조도와 기계적 성질이 향상됨을 확인 할 수 있었다. 비정질구조를 가지는 박막 중, Yb-doped 3.2at% ITO타겟으로 증착하고, $170^{\circ}C$에서 어닐링처리 하였을 때, 가장 낮은 비저항 $4.672{\times}10^{-4}{\Omega}cm$을 나타내었다. ITO:Yb 박막의 전기적 특성은 Hall 효과 측정장비, 박막의 결정구조는 X-선 회절 (XRD), 표면조도는 AFM 장비를 사용하여 측정하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.4
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• pp.159-163
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• 2016

Up-conversion (UC) luminescence properties of polycrystalline $Er^{3+}/Yb^{3+}$ doped $NaGd(MoO_4)_2$ phosphors synthesized by a simple solid-state reaction method were investigated in detail. Used to 980 nm excitation (InfraRed area), $Er^{3+}/Yb^{3+}$ co-doped $NaGd(MoO_4)_2$ exhibited very weak red emissions near 650 and 670 nm, and very strong green UC emissions at 540 and 550 nm corresponding to the infra 4f transitions of $Er^{3+}(^4F_{9/2},\;^2H_{11/2},\;^4S_{3/2}){\rightarrow}Er^{3+}(^4I_{15/2})$. The optimum doping concentration of $Er^{3+}$, $Yb^{3+}$ for highest emission intensity was determined by XRD and PL analysis. The $Er^{3+}/Yb^{3+}$ (10.0/10.0 mol%) co-doped $NaGd(MoO_4)_2$ phosphor sample exhibited very strong shiny green emission. A possible UC mechanism for $Er^{3+}/Yb^{3+}$ co-doped $NaGd(MoO_4)_2$ depending on the pump power dependence was discussed.