• Title, Summary, Keyword: $Dy_2$$O_3$

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Study on the Sinterability and Pellet Properties of Dy2O3-TiO2 Oxides (Dy2O3-TiO2 산화물의 소결성 및 소결체 특성에 관한 연구)

  • Kim, Han-Soo;Joung, Chang-Yong;Kim, Si-Hyung;Lee, Byoung-Ho;Lee, Young-Woo;Sohn, Dong-Seong;Lee, Sang-Hyun
    • Journal of the Korean Ceramic Society
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    • v.39 no.11
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    • pp.1108-1112
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    • 2002
  • pellets were fabricated as a reactor control material by the powder process. Sinterability of $Dy_2O_3+TiO_2$ mixtures and phases of solid solutions were analyzed by using TMA and XRD, respectively. The thermal conductivity of pellet was determined from the measurement data of the specific heat and the thermal diffusivity of the pellet. The sinterability and the sintered density varied as a function of Dy content in $Dy_xTi_yO_z$. The pellet of $3\;g\;Dy/cm^3\;Dy_xTi_yO_z$ melted in the sintering temperature of $1580{\circ}C$. There were two phases of $Dy_2TiO_5+Dy_2Ti_2O_7$ and a single phase of $Dy_2TiO_5$ for the pellet that has the Dy content of and , respectively. The thermal conductivity of $Dy_xTi_yO_z$ was nearly constant in the temperature range of $25~600{\circ}$. It was 1.69~1.78 W/mK for the pellet sintered in and 1.49~1.55 W/mK for the pellet sintered in $1550{\circ}$.

Surge Current Characteristics of ZnO-$Pr_6O_{11}$-CoO-$Cr_2O_3-Dy_2O_3$-based Varistors (ZnO-$Pr_6O_{11}$-CoO-$Cr_2O_3-Dy_2O_3$계 바리스터의 써지전류 특성)

  • Kim, Myung-Jun;Yoo, Dea-Hoon;Park, Jong-Ah;Nahm, Choon-Woo
    • Proceedings of the KIEE Conference
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    • pp.1631-1633
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    • 2004
  • The surge current characteristics of ZnO-$Pr_6O_{11}$-CoO-$Cr_2O_3-Dy_2O_3$-based varistors were investigated with various $Dy_2O_3$ contents. The sintered density decreased in the range of $5.2{\sim}4.6g/cm^3$ with increasing $Dy_2O_3$ content. The incorporation of $Dy_2O_3$ markedly enhanced the nonlinear properties of varistors above 10 times in nonlinear exponent, compared with the varistor without $Dy_2O_3$. The varistor ceramics doped with 0.5 mol% $Dy_2O_3$ exhibited the highest electrical stability. However, the remainder varistors resulted in thermal runaway due to low density of varistor ceramics. The clamping voltage ratio exhibited a minimum value of 2.03 in 1.0 mol% $Dy_2O_3$ at surge current of 100 A(8/20 ${\mu}s$).

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Influence of Dy2O3 Addition on Microstructure and Electrical Properties of Pr6O11 Varistor Ceramics (Pr6O11계 ZnO 바리스터 세라믹스의 미세구조 및 전기적 특성에 미치는 Dy2O3첨가의 영향)

  • Nahm, Choon-Woo;Park, Jong-Ah
    • Korean Journal of Materials Research
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    • v.13 no.10
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    • pp.645-650
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    • 2003
  • The microstructure and electrical characteristics of $Pr_{6}$ $O_{11}$ -based ZnO varistor ceramics composed of $ZnO-Pr_{6}$ $O_{ 11}$/$-CoO-Cr_2$$O_3$-$Dy_2$$O_3$-based ceramics were investigated with $Dy_2$$O_3$content in the range of 0.0∼2.0 mol%. As $Dy_2$$O_3$content was increased, the average grain size was decreased in the range of 18.6∼4.7 $\mu\textrm{m}$ and the density of the ceramic was decreased in the range of 5.53∼4.34 g/㎤. While, the varistor voltage was increased in the range of 39.4∼436.6 V/mm and the nonlinear exponent was in the range of 4.5∼66.6 with increasing $Dy_2$$O_3$content. The addition of $Dy_2$$O_3$highly enhanced the nonlinear properties of varistors, compared with the varistor without $Dy_2$$O_3$. In particular, the varistor with $Dy_2$$O_3$ content of 0.5 mol% exhibited the highest nonlinearity, in which the nonlinear exponent is 66.6 and the leakage current is 1.2 $\mu\textrm{A}$. The donor concentration and the density of interface states were decreased in the range of $(4.19∼0.33) ${\times}$10^{18}$ //㎤ and $(5.38∼1.74) ${\times}$10^{12}$ $\textrm{cm}^2$, respectively, with increasing $Dy_2$$O_3$content. The minimum dissipation factor of 0.0302 was obtained from 0.5mol% $Dy_2$$O_3$.

Electrical and Dielectric Properties of Zn-Pr-Co-Cr-Dy Oxides-based Varistors (Zn-Pr-Co-Cr-Dy 산화물계 바리스터의 전기적, 유전적 특성)

  • 남춘우;박종아;김명준;류정선
    • Journal of the Korean Ceramic Society
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    • v.40 no.10
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    • pp.943-948
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    • 2003
  • The microstructure and electrical characteristics of Zn-Pr-Co-Cr-Dy oxides-based varistors were investigated with Dy$_2$ $O_3$ content in the range of 0.0∼2.0 ㏖%. As Dy$_2$ $O_3$ content is increased, the average grain size was decreased in the range of 18.2∼4.6 $\mu\textrm{m}$ and the ceramic density was decreased in the range of 5.49∼4.64 g/㎤. The incorporation of Dy$_2$ $O_3$ markedly enhanced the nonlinear properties of varistors more than 9 times in nonlinear exponent, compared with the varistor without Dy$_2$ $O_3$ The varistor with 0.5∼1.0 ㏖% Dy$_2$ $O_3$ exhibited the high nonlinearity, in which the nonlinear exponent is above 55 and the leakage current is below 1.0 ${\mu}\textrm{A}$. The donor concentration and the density of interface states were decreased in the range of (4.66∼0.25)${\times}$10$\^$18//㎤ and (5.70∼1.39)${\times}$10$\^$12//$\textrm{cm}^2$, respectively, with increasing Dy$_2$ $O_3$ content. The minimum dielectric dissipation factor of 0.0023 was obtained for 0.5 ㏖% Dy$_2$ $O_3$, but further addition of Dy$_2$ $O_3$ increased it.

Influence of Addition of Dysprosium on Electrical properties of Praseodymium-based ZnO Varistor Ceramics (프라세오뮴계 ZnO 바리스터 세라믹스의 전기적 특성에 디스프로시움 첨가의 영향)

  • Kim, Hyang-Suk;Nahm, Choon-Woo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.625-628
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    • 2002
  • The electrical properties of the praseodymium-based ZnO varistor ceramics, which are composed of Zn-Pr-Co-Cr-Dy oxides were investigated with $Dy_2O_3$ amount. The average grain size of varistor ceramics was greatly decreased from 18.2 to 4.6 pm with increasing $Dy_2O_3$ amount. The calculated nonlinear exponent$({\alpha})$ in varistor ceramics without $DY_2O_3$ was only 4.9, whereas the a value of the varistors with $DY_2O_3$ was abruptly increased in the range of 48.8 to 58.6. In particular, the maximum value of a was obtained by doping of 1.0 mol% $DY_2O_3$, reaching 58.6. The measured leakage current$(I_l)$ value in varistors without $DY_2O_3$ was $85.45{\mu}A$, whereas the $I_{\ell}$ value of the varistors with $DY_2O_3$ was very abruptly decreased in the range of 1.10 to $0.12{\mu}A$. In particular, the minimum value of $I_{\ell}$ was obtained by doping of 0.5 mol% $DY_2O_3$, reaching $0.12{\mu}A$. The tan $\delta$ varied in V-shape, with minimum 2.28% at 0.5 mol% $DY_2O_3$. The donor concentration and the density of interface states were decreased in the range of $(4.66{\sim}0.25){\times}10^{18}cm^3$ and $(5.70{\sim}1.39){\times}10^{12}/cm^2$, respectively, as $DY_2O_3$ amount is increased.

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The influence of doping $DY_2O_3$ on electrical properties of (Ba,Sr,Ca)$TiO_3$ thick films ((Ba,Sr,Ca)$TiO_3$ 후막의 전기적 특성에 미치는 $Dy_2O_3$첨가의 영향)

  • Noh, Hyun-Ji;Lee, Sung-Gap;Lee, Young-Hie;Nam, Sung-Pill
    • Proceedings of the KIEE Conference
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    • pp.173-174
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    • 2008
  • 페로브스카이트 구조의 (Ba,Sr,Ca)$TiO_3$ 분말에 $Dy_2O_3$ 불순물을 첨가하여 첨가량에 따른 영향을 연구하였다. 시편의 제작은 Screen-printing을 이용하여 후막으로 제작하였으며, 구조적인 특성과 전기적인 특성을 관찰하였다. XRD 회절 분석을 통하여 $Dy_2O_3$가 첨가된 모든 시편에서 이차상이 없는 전형적인 페로브스카이트 구조를 나타내었다. 시편의 미세구조를 관찰한 결과 grain size는 $Dy_2O_3$ 첨가량이 증가 할수록 감소하였으며, 기공은 증가하는 것을 알 수 있었다. 후막의 두께는 $Dy_2O_3$ 첨가량에 영향을 받지 않았으며 평균 두께는 $69{\mu}m$이었다. 큐리 온도는 $Dy_2O_3$ 첨가량에 따라 감소하였으며, 유전 손실은 상온 이상에서 1%이하로 크게 감소하였다.

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Effects of $Dy_2$$O_3$ composition for the photoluminescence and long-phosphorescent characteristics of stuffed tridymite $SrAl_2$$O_4$ : $Eu^{2+}$ phosphors (Stuffed tridymite계 $SrAl_2$$O_4$ : $Eu^{2+}$ 형광체의 발광 및 장잔광특성에 미치는 $Dy_2$$O_3$의 영향)

  • 이영기;김병규
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.11 no.2
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    • pp.71-77
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    • 2001
  • We investigated photoluminescence, long-phosphorescent and crystalline properties with various $Dy_2$$O_3$ compositions (0.0~9.5mol%) in $SrAl_2$$O_4$ : $Eu^{2+}$,$Dy^{3+}$ phosphor powders prepared by the solid state reaction. The highest emission wavelength (520nm) of photoluminescence spectra was not affected by the Dy doping concentrations. The$SrAl_2$$O_4$single phase which was determined by X-ray diffraction and photoluminescence was appeared for the concentrations of $Dy_2$$O_3$$\leq$1.0 mol%. After removal of the pulsed Xe-lamp excitation (360nm), also, excellent long phosphorescent properties of the phosphors were obtained with the concentrations of $Dy_2$$O_3$$\leq$1.0mol%, although the decay time for all phosphors decrease exponentially.

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Growth of long persistent $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ phosphor single crystals by the Verneuil method (베르누이법 의한 장잔광성 $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ 단결정 성장)

  • Nam, Kyung-Ju;Choi, Jong-Keon
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.15 no.6
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    • pp.225-228
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    • 2005
  • We have grown the long persistent $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ phosphor single crystal by Verneuil method. The obtained single crystals were long persistent phosphorescence peaking at ${\lambda}=520nm$ with a size of about 5 mm diameter, 55 mm length. The melting temperature of $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ measured $T_{mp}=1968^{\circ}C$. The optimum composition was $SrCO_3:Al(OH)_3:Eu_2O_3:Dy_2O_3$ = 1 : 2 : 0.015 : 0.02. Flow rate of $H_2:O_2$ is about 4 : 1. Growthing rate is about 5 mm/hr. The spectra of the phosphorescence from the crystals are quite similar to those obtained with sintered powders used for luminous pigments. The crystalline structure of long persistent $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ phosphor single crystal was determined by X-ray diffraction.

Influence of Dy Doping on Electrical Properties and dc Aging Behaviors of Zn-Pr-Co-Cr System

  • Nahm, Choon-Woo
    • Transactions on Electrical and Electronic Materials
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    • v.8 no.6
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    • pp.234-240
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    • 2007
  • The electrical properties and dc aging behavior for specified stress state of system, which is composed of quaternary Zn-Pr-Co-Cr, were investigated for different $Dy_2O_3$ addition doping level. As $Dy_2O_3$ doping level increased, the density decreased in the range of 5.51-4.90 $g/cm^3$, reaching maximum at 0.5 mol% and the average ZnO grain size decreased in the range of 17.7-6.0 ${\mu}m$. The incorporation of $Dy_2O_3$ significantly improved the non-ohmic properties, above 30 in non-ohmic coefficient, compared with that of undoped samples. The samples with the best performance of non-ohmic properties were obtained for $Dy_2O_3$ doping level of 1.0 mol%, with 49 in non-ohmic coefficient and 2.6 ${\mu}A/cm^2$ in leakage current. The samples with the highest stability were obtained for $Dy_2O_3$ doping level of 0.5 mol%.

Microstructure and Varistor Characteristics of ZnO-Pr6O11-CoO-Cr2O3-Dy2O3-Based Varistors (ZnO-Pr6O11-CoO-Cr2O3-Dy2O3계 세라믹스의 미세구조 및 바리스터 특성)

  • 남춘우;박종아;김명준
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.10
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    • pp.897-901
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    • 2003
  • The microstructure and varistor characteristics of ZnO-Pr$_{6}$O$_{11}$-CoO-Cr$_2$O$_3$-Dy$_2$O$_3$(ZPCCD)-based ceramics were investigated with Dy$_2$O$_3$ content in the range of 0.0∼2.0 mol%. As Dy$_2$O$_3$ content is increased, the average grain size was decreased in the range of 18.6∼4.7 $\mu$m and the density was decreased in the range of 5.53∼4.34 g/cm$^3$. While, the varistor voltage was increased in the range of 39.4∼436.6 V/mm and the nonlinear exponent was in the range of 4.5-66.6 with increasing Dy$_2$O$_3$ content. The addition of Dy$_2$O$_3$ highly enhanced the nonlinear properties of varistors, compared with the ceramics without Dy$_2$O$_3$ Particularly, the ceramics with Dy$_2$O$_3$ content of 0.5 mol% exhibited the highest nonlinearity, in which the nonlinear exponent is 66.6 and the leakage current is 1.2 $\mu$A.A.A.