• Title/Summary/Keyword: $Nb_2O_5$

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Optical properties of Nb2O5 thin films prepared by ion beam assisted deposition (이온빔 보조 증착 Nb2O5 박막의 광학적 특성)

  • 우석훈;남성림;정부영;황보창권;문일춘
    • Korean Journal of Optics and Photonics
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    • v.13 no.2
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    • pp.105-112
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    • 2002
  • We studied the optical and structural properties of conventional and ion-beam-assisted-deposition (IBAD) Nb$_2$O$_{5}$ films which were evaporated by an electron beam gun. The vacuum-to-air spectral shift and the cross sectional SEM images of the Nb$_2$O$_{5}$ films were investigated. The results show that the IBAD Nb$_2$O$_{5}$ films have a higher packing density than the conventional Nb$_2$O$_{5}$ films. The average refractive index of IBAD Nb$_2$O$_{5}$ films was increased, while the extinction coefficient was decreased compared with the conventional films. As the oxygen flow was increased, the average refractive index and extinction coefficient of the conventional and IBAD films decreased. Both the conventional and IBAD Nb$_2$O$_{5}$ films showed inhomogeneity in refractive index, and the degree of inhomogeneity of the IBAD Nb$_2$O$_{5}$ films became larger as the ion current density was increased. All Nb$_2$O$_{5}$ films were found to be amorphous by x-ray diffraction (XRD) analysis, and hence the crystal structure of Nb$_2$O$_{5}$ films was not changed by IBAD.

Variation of Band Gap Energy upon Structural Distortion for Nb-containing Oxyfluorides (Nb를 포함하는 불소산화물에서 구조적 뒤틀림에 따른 에너지 띠 간격의 변화)

  • Kim, Hyun-Jun;Kim, Seung-Joo
    • Journal of the Korean Chemical Society
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    • v.51 no.3
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    • pp.265-269
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    • 2007
  • A comparative study on crystal structures and UV-visible diffuse reflectance spectra for Nb-containing oxyfluorides was performed to probe the relationship between energy band gap and local structure. The oxyfluorides, RbSrNb2O6F, RbCaNb2O6F and RbNb2O5F are commonly composed of the corner-sharing NbO5F octahedra as structural building units. The average Nb-O(F)-Nb bond angles, which can be a measure of the structural distortion, are 158.6° for RbSrNb2O6F, 149.6° for RbCaNb2O6F and 139.5° for RbNb2O5F. As the bond angle decreases, the band gap increases: 3.48eV for RbSrNb2O6F, 3.75eV for RbCaNb2O6F and 4.03 eV for RbNb2O5F. This experimental result implies that the band gap can be controlled with a range of 0.6 eV through a variation of local structure for the Nb-containing oxyfluorides.

The Structural properties of $BaTiO_3+Nb_2O_5$ ceramics with sintering temperature (소결온도에 따른 $BaTiO_3+Nb_2O_5$ 세라믹스 구조적 특성)

  • Lee, Sang-Chul;Kim, Ji-Heon;Kim, Kang;Ryu, Ki-Won;Lee, Young-Hie
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.05c
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    • pp.127-130
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    • 2001
  • The $BaTiO_3+xNb_2O_5$(x=6, 8, 10wt%) ceramics were prepared by conventional mixed oxide method. The structural properties of the $BaTiO_3+Nb_2O_5$ ceramics with the sintering temperature and addition of $Nb_2O_5$ were investigated by XRD and SEM. Increasing the sintering temperature, the $2{\theta}$ value of BT(110) peak was shifted to the lower degree and intensity of the $Ba_6Ti_2Nb_8O_{30}$ (133) peak was increased. Increasing the addition of $Nb_2O_5$, the intensity of $BaTiNb_4O_{13}$ (201) peak was decreased and $Ba_6Ti_2Nb_8O_{30}$ (133) peak was increased. The grain size of the $BaTiO_3+Nb_2O_5$ ceramics sintered at $1500^{\circ}C$ were almost uniform.

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Microstructure and Mechanical Properties of $Al_2O_3$-$ZrO_2$-Nb Composites Prepared by Reaction Sintering (반응소결로 얻어진 $Al_2O_3$-$ZrO_2$-Nb 복합체의 미세구조와 기계적 성질)

  • ;;;R.J. Brook
    • Journal of the Korean Ceramic Society
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    • v.28 no.5
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    • pp.422-428
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    • 1991
  • The reaction sintering of Al2O3-ZrO2-Nb composite has been investigated using Al2O3, and ZrAl2 powders. Two kinds of specimens, 78.3Al2O3-14.0Nb2O5-7.7ZrAl2 in wt.% (AZN-5) and 72.3Al2O3-13.8Nb2O5-7.5ZrAl2-6.4ZrO2(AZN-10), were prepared. Powder compacts were sintered at various temperatures between 1$600^{\circ}C$ and 1$700^{\circ}C$ for 30 min in Ar. DTA and X-ray analysis have showen that a reaction between Nb2O5 and ZrAl2 started at 149$0^{\circ}C$ to form Al2O3, ZrO2, and Nb. The sintered density increased with the sintering temperature. AZN-10 specimen showed higher density than AZN-5 specimen for almost all the experimental conditions. Al2O3-ZrO2-Nb composite hot pressed after reaction sintering showed higher toughness and lower hardness than hot pressed Al2O3-ZrO2. The crack propagated through many metallic Nb particles which showed plastic deformation, and this is the cause of the increase in toughness of Al2O3-ZrO2-Nb composite over Al2O3-ZrO2.

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Effects of Nb$_2$O$_{5}$ Addition on the Electromagnetic Properties of Mn-Zn Ferrites (Nb$_2$O$_{5}$ 첨가가 Mn-Zn Ferrites의 전자기적 특성에 미치는 효과)

  • Suh, Jung-Ju;Shin, Myung-Seung;Han, Young-Ho
    • Korean Journal of Materials Research
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    • v.5 no.8
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    • pp.1026-1034
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    • 1995
  • It is well known that the addition of CaO-SiO$_2$to Mn-Zn ferrites forms an insulating grain bounary layer with high electrical resistivity. This study investigated the effect of Nb$_2$O$_{5}$ on the electromagnetic properties of high frequency low loss Mn-Zn ferrites. The addition of 300ppm Nb$_2$O$_{5}$ developed an exaggerated grain growth while the addition of CaO-SiO$_2$addition with 200ppm Nb$_2$O$_{5}$ more effectively increased the density than that without Nb$_2$O$_{5}$. The addition of Nb$_2$O$_{5}$ showed the lower power loss below 100 ppm SiO$_2$and the Nb$_2$O$_{5}$-CaO addition lowered the power loss at higher sintering temperature.

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Piezoelectric Properties of Ag2O Doped 0.95(Na,K)NbO3-0.05LiNbO3 Ceramics (Ag2O 첨가량에 따른 0.95(Na,K)NbO3-0.05LiNbO3 세라믹스의 압전 특성)

  • Chae, Moon-Soon;Shin, Dong-Jin;Koh, Jung-Hyuk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.6
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    • pp.435-438
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    • 2012
  • As lead-free piezoelectric materials, $Ag_2O$ doped $0.95(K_{0.5}Na_{0.5})NbO_3-0.05LiNbO_3+x$ mol% (where x = 0, 0.5, 1, 1.5, 2, 2.5 and 3, respectively) ceramics were fabricated by a conventional sintering process. The doping effects on the microstructure and electrical properties of the $0.95(K_{0.5}Na_{0.5})NbO_3-0.05LiNbO_3$ ceramics were systematically investigated. When the 3 mol % $Ag_2O$ doped $0.95(K_{0.5}Na_{0.5})NbO_3-0.05LiNbO_3$ samples were sintered at $1,080^{\circ}C$ for 5 hrs in air, these ceramics showed excellent values of density=4.20 $g/cm^3$, piezoelectric constant ($d_{33}$)=174 pC/N and phase transition temperature$(T_c)=421.6^{\circ}C$, respectively.

The stuctural and dielectric properties of the $BaTiO_{3}+xNb_{2}O_{5}$ ceramics ($BaTiO_{3}+xNb_{2}O_{5}$ 세라믹스의 구조 및 유전특성)

  • Lee, Sang-Chul;Ryu, Ki-Won;Lee, Sung-Gap;Lee, Young-Hie
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.426-429
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    • 2001
  • The $BaTiO_{3}+xNb_{2}O_{5}$[x=6, 8, 10wt%] ceramics were prepared by conventional mixed oxide method. The structural properties of the $BaTiO_{3}+xNb_{2}O_{5}$ ceramics with the sintering temperature and addition of $Nb_{2}O_{5}$ were investigated by XRD and SEM. Increasing the sintering temperature, the $2{\Theta}$ value of BT (110) peak was shifted to the lower degree and intensity of the BN (310) peak was increased. Increasing the addition of $Nb_{2}O_{5}$, the intensity of BN (100) peak was decreased and BN (310), (110) peaks were increased. The grain size of the $BaTiO_{3}+xNb_{2}O_{5}$ ceramics sintered at $1350^{\circ}C$ were almost uniform. In the $BaTiO_{3}+xNb_{2}O_{5}$ ceramics sintered at $1350^{\circ}C$, the dielectric constant and dielectric loss were 5424, 0.02 respectively.

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The structural and dielectric properties of the $BaTiO_{3}+xNb_{2}O_{5}$ ceramics ($BaTiO_{3}+xNb_{2}O_{5}$ 세라믹스의 구조 및 유전특성)

  • 이상철;류기원;이성갑;이영희
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11a
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    • pp.426-429
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    • 2001
  • The BaTiO$_3$+xNb$_2$O$_{5}$[x=6,8 , 10wt%] ceramics were prepared by conventional mixed oxide method. The structural properties of the BaTiO$_3$+xNb$_2$O$_{5}$ ceramics with the sintering temperature and addition of Nb$_2$O$_{5}$ were investigated by XRD and SEM. Increasing the sintering temperature, the 2$\theta$ value of BT (110) peak was shifted to the lower degree and intensity of the BN (310) peak was increased. Increasing the addition of Nb$_2$O$_{5}$, the intensity of BN (100) Peak was decreased and BN (310), (110) peaks were increased. The grain size of the BaTiO$_3$+Nb$_2$O$_{5}$ ceramics sintered at 135$0^{\circ}C$ were almost uniform. In the BaTiO$_3$+Nb$_2$O$_{5}$ ceramics sintered at 135$0^{\circ}C$, the dielectric constant and dielectric loss were 5424, 0.02 respectively.espectively.

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Investigation of low temperature sintering property and fabrication in $Bi_2(Zn_{1/3}Nb_{2/3})_2O_7\;and\;(Bi_{1.5}Zn_{0.5})(Zn_{0.5}Nb_{1.5})O_7$ pyrochlore ($Bi_2(Zn_{1/3}Nb_{2/3})_2O_7\;and\;(Bi_{1.5}Zn_{0.5})(Zn_{0.5}Nb_{1.5})O_7$ pyrochlore의 제조 및 저온 소결 특성 고찰)

  • Kim, Kwan-Soo;Yoon, Sang-Ok;Kim, Shin;Kim, Yun-Han;Kwan, Oh-Young;Park, Jong-Guk;Shim, Sang-Heung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.245-245
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    • 2007
  • 본 연구는 $Bi_2O_3$, ZnO 및 $Nb_2O_5$로 이루어진 두 가지의 $Bi_2(Zn_{1/3}Nb_{2/3})_2O_7$$(Bi_{1.5}Zn_{0.5})(Zn_{0.5}Nb_{1.5})O_7$ pyrochlore를 제조한 후, ZBS 및 BZBS 유리를 각각 첨가하여 저온 소결 및 마이크로파 유전 특성을 고찰하였다. 두 가지의 pyrochlore에 대하여 하소 온도에 따른 상 합성 유무를 고찰한 결과 $900^{\circ}C$에서 단일 상을 갖는 pyrochlore를 제조할 수 있었다. 두 가지의 pyrochlore에 ZnO-rich ZBS 유리와 $Bi_2O_3$-rich BZBS 유리를 3, 5 wt%로 첨가한 후 $800{\sim}950^{\circ}C$에서 소결한 결과 ZBS 및 BZBS 유리를 5wt%를 첨가하였을 때 $900^{\circ}C$에서 소결이 가능하였다. 또한 마이크로파 유전 특성을 고찰한 결과, $(Bi_{1.5}Zn_{0.5})(Zn_{0.5}Nb_{1.5})O_7$의 pyrochlore는 고주파에서 유전 특성 측정이 되지 않았다. $Bi_2(Zn_{1/3}Nb_{2/3})_2O_7$의 pyrochlore의 경우 5 wt% ZBS 및 BZBS 유리를 첨가하여 $900^{\circ}C$에서 소결한 시편의 마이크로파 유전 특성은 ${\varepsilon}_r$= 62.8~68.3, $Q{\times}f$ value= 3,500~2,700 GHz을 나타내었다.

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Growth of potassium lithium niobate (KLN) single crystal with high $Nb_2O_5$content ($Nb_2O_5$함량이 높은 potassium lithium niobate(KLN) 단결정의 성장)

  • 강길영;윤종규
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.3
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    • pp.396-400
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    • 1998
  • The physical properties of KLN single crystals very significantly according to the $Nb_2O_5$ content in grown crystal, therefore, it is very important to control the composition of KLN single crystals. In this study, KLN single crystals of high content $Nb_2O_5$ were grown by temperature fluctuation and TSSG (Top-seeded solution growth) methods with increasing the $Nb_2O_5$ content of starting solution. To investigate the existence of defect due to the increase of $Nb_2O_5$ content, dielectric and optical properties were measured. Due to the increase of defects in grown KLN single crystal, the shift of cutoff-frequency to lower energy and a broad Curie range, which shows the DPT (diffuse phase transition) characteristics, were observed.

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