• Title/Summary/Keyword: Yttrium addition

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Effects of Excess Yttrium Addition on YBCO Thin Films Prepared by TFA-MOD Process (MOD-TFA 공정에 의한 YBCO박막제조시 과잉 yttrium첨가 효과에 관한 연구)

  • Lee Seung-Yi;Song Seul-A;Kim Byeong-Joo;Park Jin-A;Kim Ho-Jin;Lee Hee-Gyoun;Hong Gye-Won;Jang Seog Heon;Joo Jinho;Yoo Jai-Moo;Pradeep Halder
    • Progress in Superconductivity
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    • v.7 no.1
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    • pp.87-91
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    • 2005
  • [ $YBa_{2}Cu_{3}O_{7-x}$ ] thin films were fabricated on $LaAlO_3$(100) substrate by TFA-MOD process. Yttrium-excess (0, 2.5, 5, 10, 15, 20 $at\%$) coating solution was prepared by adding extra amount of yttrium into a stoichiometric(Y:Ba:Cu=1:2:3) TFA precursor solution. Results are presented concerning the influence of excess yttrium additions on the microstructure development and superconducting properties of $YBa_{2}Cu_{3}O_{7-x}$ film. Large sized CuO particles was observed by SEM EDS investigation. The addition of excess yttrium affected little on $T_c$ of $YBa_{2}Cu_{3}O_{7-x}$ film. $J_c$ of YBCO film was enhanced with excess yttrium addition. Jc maximum of $2.21\;MA/cm^2$ (77 K, self field) appeared with the $15\;at\%$ addition of excess yttrium. With further yttrium addition up to $20\;at\%$, Jc decreased down to $0.9\;MA/cm^2$.

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Variations of ferroelectric properties with the addition of Yttrium acetate in the $Pb(Zr_{0.65}Ti_{0.35})O_3$ thin films prepared by Sol-Gel processing (Sol-Ge법에 의한 $Pb(Zr_{0.65}Ti_{0.35})O_3$박막의 Yttrium acetate 첨가에 따른 강유전 특성의 변화)

  • 김준한;이규선;이두희;박창엽
    • Electrical & Electronic Materials
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    • v.8 no.3
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    • pp.261-266
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    • 1995
  • In this study, PZT solutions added impurities of Yttrium acetate were prepared by sol-gel processing and were deposited on Pt/ $SiO_{2}$/Si substrates at 5000 rpm for 20 sec. using spin-coating method. Coated films were annealed at 700-750.deg. C for 30 min. using conventional furnace method. Variations of the crystallographic structure and microstructure of PZT thin films with adding impurities were observed using XRD and SEM, and the electrical properties, such as relative permittivity, tan .delta., hysteresis curves and leakage currents, were measured. As the yttrium contents were increased, the remanent polarization and coercive field were decreased. Variations of remanent polarizations and coercive fields of pure and yttrium doped specimens according to polarization reversal cycles were observed using hysteresis measurement. PZT thin films added $Y^{3+}$ ions were completely crystallized at 750.deg. C. $Y^{3+}$ ions, as donor impurity, substituted Pb.sup 2+/ ions located at A-site of perovskite structure. By substitution of $Y^{3+}$ ions, leakage currents became less by decreasing the space charges. Degradation of remanent polarizations of Yttrium added specimens after fatigue was not observed and coercive fields increased more than those of pure PZT thin films.

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Hydrogen Trapping Using Yttrium to Manage Hydrogen in HSLA Steel Welds (고장력강의 용접부에서 Yttrium을 이용한 수소의 트랩에 관한 연구)

  • Park, Yeong-Do
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.141-143
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    • 2005
  • Yttrium has been investigated as hydrogen trapping site in pure iron and HSLA steel welds. Assessment of hydrogen trapping parameters for yttrium oxide has also shown the high potential of yttrium addition to improve hydrogen management in high strength steel welding. The purpose of this study was to reduce and control the diffusible hydrogen content in the weld deposit.

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Recovery of Yttrium from the Sludge Generated in Recycling Process of the Obsolete CRT (폐CRT의 재활용 공정에서 발생한 슬러지로부터 Y의 회수)

  • 전준미;이재천;정진기;김남철
    • Resources Recycling
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    • v.10 no.6
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    • pp.22-28
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    • 2001
  • A study on the recovery of yttrium was conducted using the phosphor sludges generated in the recycling process of obsolete CRTs. Yttrium was leached by HCl and $HNO _3$. The leaching efficiency of yttrium was extensively investigated in terms of acid concentration, leaching temperature and time, and pulp density. Yttrium and lead was recovered from leaching solutions also by precipitation method. The leaching behavior of yttrium was similar in both acids. The leaching efficiency of yttrium for both acids increased with time at the conditions of 3.0M, $90^{\circ}C$, and 280 g/L of pulp density. After 40 minutes, it was saturated to 93% and 90% for HCl and HNO$_3$respectively. Yttrium was recovered from leaching acid solution by the addition of $H_2$$C_2$$O_4$while lead was removed as $PbSO_4$by $Na_2$ $SO_4$.

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Characterization of Spray-Dried Yttrium Aluminum Garnet Powder

  • Sim, S.M.
    • The Korean Journal of Ceramics
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    • v.1 no.1
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    • pp.35-39
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    • 1995
  • Yttrium aluminum garnet(YAG) powders were synthesized by spray-drying of the hydroxides coprecipitated from a mixture of aqueous solutions of $Al(NO_3)_3.9H_2O \;and\; Y(NO_3)_3.6H_2O$ Phase formation in the powders during heat treatments and their sintering charactristics were investigated. In the powder obtained by washing the hydroxides before spray-drying, a metastable yttrium aluminum hexagonal (YAH) phase was first crystallized and then transformed into YAG as temperature was increased. The formation of YAH was attributed to a deviation in compositions of the particles from the starting composition of YAG. However, the powder prepared without washing step contained a stable yttrium aluminum monoclinic(YAM) phase in addition to YAG due to a large deviation from the starting composition. A powder compact of a single phase YAG was pressureless-sintered for 4 hrs at $1700^{\circ}C$ and the density was 93% of the theoretical density.

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Effect of $Y^{3+}$ Impurity Addition on the Structural and Electrical Properties of PZT (65/35) Thin Film ($Y^{3+}$ 불순물 첨가가 PZT (65/35) 박막의 구조적, 전기적 특성에 미치는 영향)

  • 이규선;김준한;윤현상;이두희;박창엽
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1994.11a
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    • pp.24-27
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    • 1994
  • Variations with structural and electrical properties of Yttrium added PZT thin films were observed and measured respectively. Area of rosette was increased by Yttrium added and shapes of hysteresis curves were changed to slim type. $Y^{3+}$ ion substituted $Pb^{2+}$ ion and played the role of doner. Because the creation of space charges was restricted by Yttrium, degradation of remanent polarizations by cumutation of polarization reversals of PZT was protected. But coercive field was increased because of vacancies generated Yttrium added.

Microstructural evolution in liquid-phase sintered $\alpha$-silicon carbide (액상소결 $\alpha$형 탄화규소의 미세구조 변화)

  • 이종국;강현희;박종곤;이은구
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.2
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    • pp.324-331
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    • 1998
  • After the addition of yttrium aluminum garnet of 2, 5, 10 mol% as a sintering aid, $\alpha$-silicon carbides were prepared by a liquid-phase sintering at $1850^{\circ}C$, and the microstructural evolution was investigated during sintering as functions of liquid-phase amount and sintering time. The highest apparent density in each compositions was obtained in specimens sintered for 2 h, and the percentage of weight loss increased with sintering time. By increasing the amount of sintering aid (yttrium aluminum garnet), the rate of grain growth during sintering decreased, but the apparent density of sintered body increased. The phase transformation from 6H-SiC to 4H-SiC was partially observed in specimens sintered for a long time, and so, a few rod-like grains were observed.

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The Effect of Y Addition on the Microstructure and Mechanical Property of Rapidly Solidified AZ91 Alloy (급속응고한 AZ91합금의 미세조직 및 기계적 특성에 미치는 Y첨가의 영향)

  • Choi, Jae-Young;Park, Hoon-Mo;Nam, Tae-Woon
    • Journal of Korea Foundry Society
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    • v.20 no.6
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    • pp.386-394
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    • 2000
  • In the present study, the effect of yttrium addition on the microstructure and mechanical property of rapidly solidified AZ91 alloy by melt spinning process is estimated. As yttrium was added, the microstructure of RS ribbons and extrudates became finer than those of AZ91, and RE related phases $(Al_2RE)$ were formed. In the case of the addition of 3wt%Y, the microstructure of extrude showed the finest grain size. At room temperature, the AZ91 + 3wt%Y alloy showed the highest tensile strength, 352 MPA due to precipitation of ${\beta}(Mg_{17}Al_{12})$ phase and $Al_2RE$ phase. At the elevated temperature, the mechanical property of AZ91 + 3wt%Y alloy was higher than those of other Mg alloys. The reasons were that $Al_2Y$ compound was thermally stable and suppressed the grain growth. In contrast with $Al_2Y$ compounds, ${\beta}$ phase was thermally unstable and could not suppress the grain growth at the elevated temperature. Therefore, $Al_2Y$ phase contributed to improve the thermal stability of RS AZ91 alloy.

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Influence of Liquid-Phase Amount on the Microstructure and Phase Transformation of Liquid-phase Sintered Silicon Carbide (액상량이 탄화규소 소결체의 미세구조 및 상변태에 미치는 영향)

  • 이종국;강현희;박종곤;이은구
    • Journal of the Korean Ceramic Society
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    • v.35 no.4
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    • pp.413-419
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    • 1998
  • ${\beta}$-silicon carbides with yttrium aluminum garnet of 2,5,10 mol% were prepared by a liquid--phase sint-ering and the microstructural evolution and phase transformation were investigated during sintering as functions of liquid-phase amount and sintering time. The rate of grain growth decreases with the addition of the amount of yttrium aluminum garnet (YAG) in the SiC starting powder however the apparent density and the aspect ratio of grains in sintered body increase. The phase transformation from ${\beta}$-SiC to ${\alpha}$-SiC were dependent on the liquid-phase amount and sintering time.

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Modification of Yttrium-Stabilized Zirconia Ceramics Using Calcium Phosphate

  • Chang, Myung Chul
    • Journal of the Korean Ceramic Society
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    • v.50 no.4
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    • pp.257-262
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    • 2013
  • A biomimetic approach was applied for the chemical deposition of calcium phosphate (CaP) coatings on 3 mole% yttrium-stabilized zirconia [3YSZ] powders. The solid-state reaction of 3YSZ powders with the addition of CaP was investigated for the development of biodegradable zirconia ceramics. The solid-state interaction between the 3YSZ matrix powders and the CaP additives differed from the behavior of commercial zirconia matrix powders. The 3YSZ powders were chemically reacted with precursors for the CaP formation. 3YSZ powders were mixed in an aqueous solution of Ca-P precursors and the CaP was precipitated on the surface of the 3YSZ matrix powders. The CaP-doped YSZ powders were calcined at $1100^{\circ}C$ and shaped powder blocks were then fired at $1600^{\circ}C$ for 2 h. The CaP phase formation was investigated using FE-SEM and XRD analysis.