• 전자공학회논문지D
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• 제35D권7호
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• pp.109-116
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• 1998

In this work was produced and analyzed a z-cut Ti:LiNbO$_{3}$ optical waveguide which applies for various optical devices.A waveguide channel with a thickness 8 .mu.m and a length 66,000.mu.m and a mach-zehnder interferometer type waveguide were fabricated at a diffusion temperature 1050.deg. C for 6-8hours in a wet $O_{2}$ environment. The resulting Ti:LiNbO$_{3}$ optical waveguide was measured to have a Ti-strip thickness of 950.angs. and low loss. Surfaces and cross-sections of a fabricated waveguide were analysed. The mode pattern anaysis revealed that the waveguide showed a single mode at a 1550nm wavelength. The effective dimension of the waveguide was calculated by measuring a gaussian profile; Wx=10.95.mu. and Wy=9.14.mu.m. a propagation loss, of 0.50dB/cm for a TM mode and 0.45dB/cm for a TE mode, was low enough to be accepatable for optical devices.

• E2M - 전기 전자와 첨단 소재
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• 제7권5호
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• pp.417-424
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• 1994

PbNb$_{2}$O$_{6}$ piezoelectric ceramics have good properties, but the applications of them have been limited due to the problems of microstructures. In the present study, effects of additives on the phase stability, microstructure, and electrical proper-ties of ferroetectric phase were investigated. La$_{2}$O$_{3}$, Nd$_{2}$O$_{3}$ and Sm$_{2}$O$_{3}$ were added with the amounts of 1, 3, 5 mol% respectively. The results showed that single orthorhombic(ferroelectric phase) phase compared with the mixed phase of pure PbNb2O6 was obtained. In the case of 5 mol% Nd$_{2}$O$_{3}$ addition, relative density of >95% and dense microstructure with -2.mu.m grain size were obtained.d.

• 한국화재소방학회논문지
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• 제16권4호
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• pp.15-19
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• 2002

BaTiO$_3$계 PTC 서미스터의 조성개발을 위해 (Ba$_{0.95-x}$S $r_{0.05}$C $a_{x}$)$TiO_3$-$0.01TiO_2$-$0.01SiO_2$-$\alpha$MnCO_3$-$\beta$Nb_2$o_{5}$와 같은 실험조성식을 설정한 후 최적 조건하에서 적층형 PTC시편을 제작하여 실험하였다. 실험 결과, 시편제조시의 최적 소결온도와 냉각속도는 각각 $1350^{\circ}C$-2 hour및 $100^{\circ}C$/h였다. 또한 상온저항을 낮추는 효과가 있는 Dopant로서의 Ca와 Mn 그리고 피크(peak)저항값을 높일 수 있는 Nb를 Ca:5 mol%, Mn:0.08 mol%, Nb:0.18 mol%로 함으로써 비교적 낮은 상온저항과 높은 피크(peak)저항 및 양호한 온도계수 특성이 나타났으며, 화재감지센서로서의 활용 가능성을 확인하였다.다.다.

• 한국표면공학회지
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• 제44권3호
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• pp.95-104
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• 2011

Ti based nanocomposite films including V, Si and Nb (Ti-Me-N, Me=V, Si and Nb) were fabricated by hybrid physical vapor deposition (PVD) method consisting of unbalanced magnetron (UBM) sputtering and arc ion plating (AIP). The pure Ti target was used for arc ion plating and other metal targets (V, Si and Nb) were used for sputtering process at a gas mixture of Ar/$N_2$ atmosphere. Mostly all of the films were grown with textured TiN (111) plane except the Si doped Ti-Si-N film which has strong (200) peak. The microhardness of each film was measured using the nanoindentation method. The minimum value of removal rate ($0.5{\times}10^{-15}\;m^2/N$) was found at Nb doped Ti-Nb-N film which was composed of Ti-N and Nb-N nanoparticles with small amount of amorphous phases.

• 한국전기전자재료학회논문지
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• 제21권10호
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• pp.901-905
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• 2008

In this study, $0.95(K_{0.5}Na_{0.5})NbO_{3}-0.05Li(Sb_{0.8}Nb_{0.2})O_{3}+0.2\;wt%Ag_{2}O$ were investigated as a variations of sintering times in order to improve dielectric and piezoelectric properties of lead-free piezoelectric ceramics. $Ag_{2}O$ were used as sintering aids and the specimens were sintered during 3, 5, 7, 9 and 11 hours, respectively. At the specimen sintered during 7 hour, Electromechanical coupling factor ($k_p$), density, dielectric constant (${\epsilon}_{\gamma}$), piezoelectric constant ($d_{33}$) and curie temperature ($T_c$) of composition ceramics showed the optimal value of 0.450, 4.274 $[g/cm^3]$, 1007, 257 [pC/N] and $396^{\circ}C$, respectively.

• 한국전기전자재료학회논문지
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• 제21권11호
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• pp.1000-1004
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• 2008

In this paper, the influences of poling electric field on piezoelectric properties of $0.95(K_{0.5}Na_{0.5})NbO_3$-$0.05Li(Sb_{0.8}Nb_{0.2})O_3$ (abbreviated as KNN-LSN) ceramics were investigated. The specimens was sintered at sintering temperature of $1050^{\circ}C$. They showed orthorhombic phase structure without secondary phase. Electromechanical coupling factor (kp), dielectric and piezoelectric constant($d_{33}$) increased with poling electric field. However, mechanical quality factor (Qm) decreased. Take into account of poling conditions and piezoelectric properties of KNN-LSN ceramics, the optimum poling condition for KNN-LSN ceramics was poling electric field of 4.5 kV/mm. At the time, kp of 0.458, Qm of 43.97, $d_{33}$ of 278 pC/N, and dielectric constant of 1079 were shown, respectively.

• 한국통신학회논문지
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• 제22권1호
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• pp.89-95
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• 1997

X-cut y-propagation $LiNbO_{3}$ 광변조기를 해석하고, 광대역 변조특성을 얻기 위한 설계조건을 구한다. 먼저, 구성된 전극에 대하여 최대 변조효율을 얻기 위한 광도파로의 최적위치를 찾고, 다양한 설계조건에 따른 구동전압, 특성 임피던스, M/W 변조파 유효굴절율을 계산하였으며, 이와 같은 수치적 해석을 위해 유한요소법(FEM: Finite Element Method)을 사용하였다. 그리고 사용된 설계 틀의 유용성을 확인하기 위하여 Becker의 결과와 비교평가 하였다. 본 논문에서는 ridge형 도파로구조의 x-cut $LiNbO_{3}$ 광변조기에 대한 다양한 계산을 통하여, 결과적으로 $1.3{\mu}{\textrm{m}}$의 광신호에 대하여 1.8 V.cm의 구동전압과 특성임피던스 $48.13{\Omega}$ M/W(microwave) 변조파 유효굴절율 2.168을 가치는 x-cut $LiNbO_{3}$ 광변조기를 설계하였다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2009년도 학술논문요약집
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• pp.409-410
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• 2009

• 한국전기전자재료학회논문지
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• 제26권2호
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• pp.104-108
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• 2013

In this paper, the $0.95(Na_{0.5}K_{0.5})_{0.04}[(Nb_{0.8}Ta_{0.20})_{0.994}Co_{0.015}]O_3$(abbreviated as NKNT) + $0.05KNbO_3$ lead-free piezoelectric ceramics were synthesized by the conventional mixed oxide method route with normal sintering. And also, the effects of calcination temperature on the microstructure, dielectric properties, and piezoelectric properties were investigated. A polymorphic phase transition(PPT) between orthorhombic and tetragonal phases was observed in specimens calcined at $810^{\circ}C{\sim}850^{\circ}C$. The ceramics calcined at $830^{\circ}C$ showed excellent piezoelectric properties: $d_{33}$= 179 pC/N, $k_p$= 0.384, $Q_m$= 79.73). These results indicate that the ceramic is a promising candidate material for lead-free piezoelectric ceramics.

• 한국재료학회지
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• 제29권3호
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• pp.150-154
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• 2019

This study investigates the effect of MnO2 and CuO as acceptor additives on the microstructure and piezoelectric properties of $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$, which has a rhombohedral-tetragonal phase boundary composition. $MnO_2$ and CuO-added $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$ ceramics sintered at a relatively low temperature of $1020^{\circ}C$ show a pure perovskite phase with no secondary phase. As the addition of $MnO_2$ and CuO increases, the sintered density and grain size of the resulting ceramics increases. Due to the difference in the amount of oxygen vacancies produced by B-site substitution, Cu ion doping is more effective for uniform grain growth than Mn ion doping. The formation of oxygen vacancies due to B-site substitution of Cu or Mn ions results in a hardening effect via ferroelectric domain pinning, leading to a reduction in the piezoelectric charge coefficient and improvement of the mechanical quality factor. For the same amount of additive, the addition of CuO is more advantageous for obtaining a high mechanical quality factor than the addition of $MnO_2$.