• Journal of the Korean Ceramic Society
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• v.24 no.5
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• pp.491-499
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• 1987

Silicon nitride powder synthesized from Kimcheon quartzite and commercial reagents, AlN and Y2O3 powders were used to prepare the partially and fully stabilized Y-${\alpha}$-Sialon ceramics by the pressureless sintering at 1800$^{\circ}C$ for 2 hours in N2 atmosphere. Good mechanical properties of the prepared Y-${\alpha}$-Sialon ceramics were found over 0.4∼0.6 of the Yttrium solubility range, X, in the equation Yx(Si12-4.5x, Al4.5x)(O1.5x, N16-1.5x). The properties of these prepared Y-${\alpha}$-Sialon ceramics were compared with those prepared in the same way from a commercial Toshiba Si3N4 powder.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.31.1-31.1
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• 2011

$Li_4Ti_5O_{12}$ is emerging as a promising material with its good structure stability and little volume change during the electrochemical reaction. However, its electrochemical performance is significantly limited by low electronic or ionic conductivity. In addition, high tap density is needed forim proving its volumetric energy density and commercialization. To enhance these properties, the spherical-like $Li_4Ti_5O_{12}$ particles were synthesized and carried out doping with yttrium. Prepared Y-doped $Li_4Ti_5O_{12}$ as a anode material showed great capacity retention rate of 92% (5C/0.2C), compared with no dope done. Consequently, it was found that Y doping into $Li_4Ti_5O_{12}$ matrix reduces the polarization and resistance on SEI layer during the electrochemical reaction.

• Journal of the Korean Ceramic Society
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• v.35 no.3
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• pp.245-250
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• 1998

Field emission display (FED) is currently being explored as a potential flat panel display technology. The need of new materials for low voltage blue phosphors for FED focused our attention on the $Y_2O_3-Nb_2O_5$ sys-tem. Yttrium niobate doped with $Bi^{3+}$ was prepared by solid state reaction technique and the optimization of the luminescent properties with a control of $Bi^{3+}$ amounts and Y/Nb ratio was studied. Under 254 nm and low voltage electron excitations $Bi^{3+}-activated$ YNbO4 phosphors showed a strong and relatively narrow blue em-ission band with a range of 420 to 450 nm, Especially 0.4wt% $Bi^{3+}\;doped\;YNbO_4$ phosphors with Y/Nb ratio of 1/1 showed the maximum emission intensity. Under low voltage electron excitation maximum emission in-tensity appeared at the Y/Nb ratio of 0.495/0.505.

• Journal of Chest Surgery
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• v.44 no.4
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• pp.311-313
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• 2011

Hemangiomas that arise in cervical esophagus are extremely rare, representing 3.3% of all benign esophageal tumors. Although endoscopic mucosal resection (EMR) and potassium titanyl phosphate/yttrium aluminum garnet (KTP/YAG) laser therapy have been used with success for small tumors, the safety and efficacy in the case of large tumors remains uncertain. We report the successful resection of cervical esophageal hemangioma through a cervical esophagotomy in a patient with thyroid cancer who needed a cervical collar incision.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.11-16
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• 2007

The existence of grooves on the surface of bond coat has significant effect on the instability of thermal barrier system. In this work, the thermal-mechanical fatigue experiments were performed under various thermal and mechanical loads for FeCralloy specimens with and without yttrium dopant to observe the deformation of surface grooves. The effect of temperature, fatigue load and the ratio of curvature on the deformation of grooves were investigated. As the results, it has been found that the higher load level and the higher curvature ratio induces the larger deformation near the grooves. However, the addition of yittrium dopant induces the adverse results.

• Journal of Powder Materials
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• v.6 no.3
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• pp.246-250
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• 1999

The effects of the ${\beta}-Si_3N_4$ starting particle size and $\alpha$/$\beta$ phase transformation during sintering process on the microstructure evolution of Yttrium $\alpha$-Sialon ceramics were investigated. As-received ${\beta}-Si_3N_4$ powder (mean particle size: 0.54$\mu$m) and classified ${\beta}-Si_3N_4$ powder(mean particle size: $0.26\mu{m}$) were used as starting powders. With decreasing the starting particle size, the growth of elongated grains was enhanced, which resulted in the whisker -like microstructure with elongated grains. These results were discussed in relation to the two-dimensional nucleation and growth theory. In the specimen heat treated at $1600^{\circ}C$ for 10h before sintering at $1950^{\circ}C$for 1h under 40atm(2-step sintering), the grain size was smaller than of the 1-step sintering at 195$0^{\circ}C$ for 1h. However, bimodal microstructure evolution were not not remarkable in both sample, which is ascribed to the $\alpha$-phase contents existing in ${\beta}-Si_3N_4$ starting powder.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1561-1564
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• 2007

$Tb^{3+}-activated$ green-emitting $(Y,Gd)Ga_3(BO_3)_4$ phosphor has been investigated. The main absorption was in the $120{\sim}238$ nm and exhibited a green emission with the 545 nm and several peaks due to inner shell transition of $Tb^{3+}$ ion. With the optimized $Tb^{3+}$ concentrations, the maximum emission brightness was 90% of the $Zn_2SiO_4$:Mn phosphor.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.784-787
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• 2008

Nanoscale $YVO_4:Eu^{3+}$ phosphor has been synthesized by a mild hydrothermal reaction at various experimental conditions. The particle and luminescent properties of nanophosphors were characterized with X-ray diffraction, electron microscopy and photoluminescence. It has been found that pH value play a key factor both controlling particle size and luminous efficiency.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.299-301
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• 1989

This study presents a method of preparing $YBa_2Cu_3O_{7-x}$ ceramic and chlorine doping in it for the purpose of Jc enhancement us ins sol-gel process.Tetramethylammonium-hydroxide and pottasium carbonate solution were added to the aqueous solution of Yttrium nitrate, Barium chloride and Copper nitrate for pH control as well as forming hydroxy-carbonate precipitation. Instead of Barium nitrate, Barium chloride was used for doping chloride impurities in the specimen. The resulted materal showed good high Tc-superconductivity after calcination. Tc and Jc value are 92 K and 120.8 $A/cm^2$ respectively.

• Journal of Magnetics
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• v.14 no.4
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• pp.165-167
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• 2009

Nano-sized Yttrium iron garnet (YIG;$Y_3Fe_5O_{12}$) particles have been synthesized by using coprecipitation and a heat treatment process. The YIG particles were made using a nitrate or a chloride salt solution. The pH concentration of the solution was fixed at 12. Spherical shaped YIG particles were made with a size of about 20 nm. The magnetization value of the particles was smaller than the bulk value but their coercive field showed a high value.