• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.20-22
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• 1999

The effect of dopant and stoichiometry on the physical and optical properties of $LiNbO_{3}$ were studied. We prepared three samples, undoped, MgO doped $LiNbO_{3}$ with congruent composition and near-stoichiometric $LiNbO_{3}$. Dielectric constant and transmittance in UV/VIS/IR light range were measured. The results showed that the features for high [Li]/[Nb] were similar to those for low [Li]/[Nb] but with high [Mg].

• Transactions on Electrical and Electronic Materials
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• v.8 no.5
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• pp.201-205
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• 2007

Low temperature sintering behavior and microwave dielectric properties of the $BiNbO_{4^-}$ and the $ZnNb_2O_{6^-}zinc$ borosilicate glass(ZBS) systems were investigated with a view to applying the composition to LTCC technology. The addition of $10{\sim}30$ wt% ZBS in both systems ensured successful sintering below $900^{\circ}C$. For the $BiNbO_{4^-}ZBS$ system, the sintering was completed when 15 wt% ZBS was added whereas 25 wt% ZBS was necessary for the $ZnNb_2O_{6^-}zinc$ system. Secondary phase was not observed in the $BiNbO_{4^-}ZBS$ system but a small amount of $ZnNb_2O_6$ with the willemite structure as the secondary phase was observed in the $ZnNb_2O_{6^-}ZBS$ system. In terms of dielectric properties, the application of the $BiNbO_{4^-}$ and the $ZnNb_2O_{6^-}ZBS$ systems sintered at $900^{\circ}C$ to LTCC were shown to be appropriate; $BiNbO_{4^-}15$ wt% ZBS($\varepsilon_r=25,\;Q{\times}f\;value=3,700GHz,\;\tau_f=-32ppm/^{\circ}C$) and $ZnNb_2O_{6^-}25$ wt% ZBS($\varepsilon_r=15.8,\;Q{\times}f\;value=5,400GHz,\;\tau_f=-98ppm/^{\circ}C$).

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.327-330
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• 2006

We investigated the usefulness of $NbO_{x}$ nanopillars as an etching mask of dry etching for the formation of Si nanodot arrays. The $NbO_{x}$ nanopillar arrays were prepared by the anodic aluminum oxidation process of Al and Nb thin films. The etch rate and etch profile of $NbO_{x}$ nanopillar arrays were examined by varying the experimental conditions such as the concentration of etch gas, coil rf power, and dc bias voltage in the reactive ion etch system using the inductively coupled plasma. As the concentration of $Cl_{2}$ gas increased, the etch rate of $NbO_{x}$nanopillars decreased. With increasing coil rf power and dc bias voltage, the etch rates were found to increase. The etch characteristics and etch mechanism of $NbO_{x}$ nanopillars were investigated by varying the etch time under the selected etch conditions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.3
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• pp.120-123
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• 2005

The 5 mol% ZnO doped $LiNbO_3$ film and the 2 mol% MgO doped $LiNbO_3$ film were grown on the $LiNbO_3$ (001) substrate by liquid phase epitaxy (LPE) method with $Li_2CO_3-V_2O_5$ flux system. The crytsallinity and the lattice mismatch between $Zn:LiNbO_3$, film and $Mg:LiNbO_3$, film were analyzed by x-ray rocking curve (XRC). In addition, the ZnO and MgO distribution in the cross-section of the multilayer thin films was observed using electron probe micro analyzer (EPMA).

• 기계와재료
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• v.21 no.4
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• pp.74-81
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• 2010

Nb 및 Nb합금은 과거 냉전시대에 우주 군사용 고온재료 중 하나로 각광을 받으며 활발한 연구개발이 이루어졌으나 고온 산화에 취약한 특성으로 인해 실제로는 크게 적용되지는 않았다. 이후 Nb은 주로 고강도 철강 및 내열합금의 합금원소로 사용되고 있다. 일부에서 Nb이 가지는 초전도 특성을 활용한 부품 개발이 진행되고 있다. 본고에서는 국내에서 많이 연구되지 않은 Nb소재의 일반적인 특징 및 공업적 응용사례에 대해 간략하게 소개를 하고자 한다. 또한, Nb이 가지는 초전도특성을 이용하여 고에너지입자 가속기의 핵심부품인 radio-frequency cavity의 개발에 대해서도 소개를 하고자 한다.

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.779-785
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• 1996

Thin $700^{\circ}C$films were formed through layer inversion of Co/Nb bilayer during rapid thermal annealing(RTA). The Nb interlayer seems to effectively prevent over-consumption of Si and to control the silicidation reaction by forming Co-Nb intermetallic compounds and removing the native oxide formed on Si substrate which interferes the uniform Co-Si interaction. The final layer structure of the Co/Nb bilayer after $700^{\circ}C$ RTA was found to be ${Nb}_{2}{O}_{3}$/${Co}_{2}$Si.CoSi/${NbCo}_{x}$/Nb(O, C)/${CoSi}_{2}$/ Si. The layer inversion and the formation of a stable CoSi, phase occurred above $700^{\circ}C$, and the Nb silicides were not found at any annealing temperature. These may be due to the formation of very stable Co-Nb intermetallic compounds and Nb oxides which limit the moving of Co and Si.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1190-1196
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• 2002

Microwave dielectric properties and multilayer characteristics $(1-x)BiNbO_4-xCaNb_2O_6$ (0${\le}$x${\le}$1.0) ceramics were investigated as a function of $CaNb_2O_6$ content. In the composition range of 0.25${\le}$x${\le}$0.75, the mixture phases of $BiNbO_4$ with stibotantalate structure and $CaNb_2O_6$ with columbite structure were detected and secondary phase or phase transition were not detected. Dielectric constant (K) of $(1-x)BiNbO_4-xCaNb_2O_6$ ceramics was largely dependent on the existing phase and could be estimated by the dielectric mixing rule calculated from maxwell equation. Typically, dielectric constant (K) of 26, quality factor (Qf) of 4300 GHz and Temperature Coefficient of resonant Frequency (TCF) of -18 ppm/${\circ}C$ were obtained for $0.5BiNbO_4-0.5CaNb_2O_6$ specimens with 0.8 wt% $CuV_2O_6$ sintered at 1000${\circ}C$ for 3h. The deviation of X-Y shrinkage and camber value of the multilayers obtained from $0.5BiNbO_4-0.5CaNb_2O_6$ green sheet sintered at 850∼950${\circ}C$ for 20 min. were smaller than those of $BiNbO_4$ multilayers.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.99-104
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• 1998

40$0^{\circ}C$ $H_2O$ steam 분위기에서 Zr-2,5wt%Nb 및 Zr-20wt%Nb 합금의 산화거동을 열처리조건에 따른 미세조직 관점에서 고찰하였으며, 형성된 oxide를 분석하여 산화기구를 규명하고자 하였다. Zr-Nb 합금의 산화거동은 열처리에 따라 협성된 조직상에 매우 민감하였는데, 주 조직인 a-Zr 상 보다는 $\beta$상들에 ($\beta$-Zr, $\beta$-Nb) 보다 큰 영향을 받는 것으로 보인다. $\beta$-Zr 상은 $\alpha$-Zr 상에 비해 부식저항성이 낮으며, 그 양에 관계없이 유사한 정도의 부식거동을 보인다. $\beta$-Nb 상의 경우, 미세한 크기로 적은양이 존재하는 경우 부식저항성에 별다른 영향이 없어 보이는 반면, 상당량의 $\beta$-Nb 상이 조대한 크기로 (약 0,2$\mu\textrm{m}$) 존재하는 경우 매우 불안정한 부식거동을 보였다. 이들 $\beta$상들의 낮은 산화저항성은 Nb$_2$O$_{5}$ 을 포함한 Nb 계 oxide의 형성에 주로 기인한 것으로 추정된다.

• Journal of the Korean Ceramic Society
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• v.38 no.1
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• pp.56-60
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• 2001

90.24 mol% ZrO$_2$-5.31 mol% $Y_2$O$_3$-4.45 mol% Nb$_2$O$_{5}$ 조성의 (Y,Nb)-TZP와 (Y,Nb)-TZP/Al$_2$O$_3$복합체를 155$0^{\circ}C$~1$600^{\circ}C$에서 1~2시간 소결하여 제조하였다. 시편의 결함에 대한 저항성을 조사하기 위하여 R-curve, Weibull modulus, slow crack growth 변수 등을 조사하였다. 실험결과, (Y,Nb)-TZP와 (Y,Nb)-TZP/Al$_2$O$_3$복합체 모두 상용 3Y-TZP 보다 우수한 결함 저항성이 관찰되었다. (Y,Nb)-TZP/Al$_2$O$_3$복합체의 결함 저항성은 $Al_2$O$_3$첨가에 의한 결정립 가교 인화, 분산강화, R-curve 효과에 의한 것으로 추정된다.

• Journal of the Korean institute of surface engineering
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• v.16 no.3
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• pp.108-123
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• 1983

순수 Mo와 Mo-Nb, Mo-Ta($\leq$10 at% Nb. Ta)합금을 1,500-2,06$0^{\circ}C$ 범위에서 탄소의 고용도를 연구하였다. 특수한 침탄방법으로 C2H2를 시편에 침탄한후 열처리하여 부분적으로 석출하거나 완전석출에 관계없는 화학적 분석방법으로 행하였다. 순수 Mo에서 최대탄소 고용도는 logCCmax = 7.02-9,490/T이다. Nb, Ta를 미량첨가하여 탄소의 최대 고용도는 Arrhenius 식을 적용할 수 없다. Nb-, Ta- 농도와 온도에 따라 Mo2C와 Nb-,Ta-를 함유한 여러 가지 탄화물상을 만들거나 $\alpha$고용체와 Mo가 포함된 NbC, TaC와 평형상태를 나타나기 때문이다. 실험온도 범위에서 Nb, Ta를 첨가량을 증가하면 탄화물 내부에 NbC, TaC로 석출된다. 고온에 용해된 a-고용체는 150-200 oK/Min으로 냉각하면 석출물은 결정입계나 결정내부에 나타난다. 순수 Mo에 Nb, Ta를 첨가하여도 경도, 파괴실험에서와 같이 인장강도는 크게 증가하지 않는다.