• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.161-164
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• 2004

In this study, to develop the composition ceramics for the Ultrasonic vibrator, $Pb(Mn_{1/3}Nb_{2/3})O_3Pb(Zr.Ti)O_3$ system ceramics were manufactured as a function of PCN substitution. Its dielectric and piezoelectric characteristics were investigated. With increasing the amount of PCN substitution, electromechanical coupling factor(kp) were increased until 3mol% PCN and that after decreased. mechanical quality factor(Qm) showed the maxinum value at 2mol% PCN. Eletromechanical coupling factor, mechanical quality factor and dielectric constant were showed optimum value at PCN 2mol% as 0.58, 1630 and 1407, respectively for ultrasonic vibrator applications.

• 대한기계학회논문집
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• 제19권9호
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• pp.2154-2164
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• 1995

In this study, a dielectric cure monitoring system which consists of an electric circuit, a sensor and a personal computer was developed to on-line monitor the dielectric properties of carbon fiber epoxy composite materials. Also, the kinetic model of carbon fiber epoxy composite materials was developed by curve fitting of differential scanning calorimetry data. The start and end points of cure and the relationship between the dissipation factor and the degree of cure were obtained by comparing the dissipation factor from the dielectric properties with the degree of cure from the DSC data. The relationship between the dissipation factor and the degree of cure was tested under various temperature profiles.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.127-130
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• 2002

In this study, development of a new LTCC material using a non-glassy system was attempted with respect to reducing the fabrication process steps and cost down. Lowering the sintering temperature can be achieved by liquid phase sintering. For LTCC application, the starting material must have quality factor as high as possible in microwave frequency range. And also, the material should have a low dielectric constant for enhancing the signal propagation speed. Regarding these factors, dielectric constants of various materials were estimated by the Clausius-Mosotti equation. Among them, CaWO$_4$ was tamed out the suitable LTCC material. CaWO$_4$ can be sintered up to 98% of full density at 1200$^{\circ}C$ for 3 hours. It's measured dielectric constant, quality factor, and temperature coefficient of resonant frequency were 10.15, 62880GHz, and -27.8ppm/$^{\circ}C$, respectively. In order to modify the dielectric properties and densification temperature, 0.5∼1.5 wt% LiF were added to CaWO$_4$. LiF addition reduced the sintering temperature/time down to 800$^{\circ}C$/10∼30min due to the reactive liquid phase sintering. Dielectric constant lowered from 10.15 to 9.38 and Q x fo increased up to 92000GHz with increasing LiF content.

• 대한전기학회논문지
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• 제43권4호
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• pp.613-619
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• 1994

Dielectric properties of Ba(ZnS11/3TTaS12/3T)OS13T+x ZnO(x=0, 0.4, 0.8, 1.0 wt%) ceramics have been investigated at microwave frequencies. With excess ZnO, the sinterability was improved and the dielectric constant($\varepsilon$S1rT) and the unloaded quality factor(QS1UT) were increased. The structure changed into hexagonal from pseudocubic as being annealed at 140$0^{\circ}C$ in excess ZnO composition. Also, the temperature coefficient of the resonant frequency ($\tau$S1fT) turned into (-)ppm/$^{\circ}C$ when sintered at 155$0^{\circ}C$ for 2 hours. But the specimen sintered in ZnO muffling showed increased density and $\varepsilon$S1rT but lowerde QS1uT. Among the specimen investigated, expecially the composition added with 0.4wt% excess ZnO showed the most optimum dielectric values ($\varepsilon$S1rT=28, QS1uT x f=120000GHz) better than those of original Ba(ZnS11/2T TaS12/3T)OS13T ceramics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.175-176
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• 2008

In this study, in order to develop the composition ceramics for lead-free ultrasonic motor, $[(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}(Nb_{0.96}Sb_{0.04})]O_3$ ceramics were fabricated using $Ag_2O$ as sintering aid and a conventional mixed oxide process and their piezoelectric and dielectric characteristics were investigated according to the $SrTiO_3$ substitution. $SrTiO_3$ substitution enhanced density, dielectric constant$(\varepsilon_r)$ and electromechanical coupling factor$(k_p)$. However, mechanical quality factor was deteriorated. At the 0.5mol% $SrTiO_3$ substitution, density, electromechanical coupling factor$(k_p)$, dielectric constant$(\varepsilon_r)$ and piezoelectric constant$(d_{33})$ of specimen showed the optimum value of 4.437g/$cm^3$, 0.457, 1294, 265pC/N, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.255-258
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• 2000

In this study, the structural, dielectric and piezoelectric properties of Pb[(Sb$\sub$1/2/Nb$\sub$1/2/)$\sub$x/- (Ni$\sub$1/3/Nb$\sub$2/3/)$\sub$0.15-x/- (Zr,Ti)$\sub$0.85/]O$_3$(x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) ceramics is investigated as a function of Pb(Sb$\sub$1/2/Nb$\sub$1/2/)O$_3$ (abbreviated PSN) substitution. With the increase of PSN substitution, the crystal structure is transO$_3$formed from the tetragonal phase to the rhombohedral phase and the grain size is decreased abruptly. The curie temperature is decreased with the PSN substitution. The dielectric constant is increased with the PSN substitution and maximum value of 2290 is obtained at 4mol% PSN. With the PSN substitution, the coercive field is increased and the remnant polarization is decreased. The Electromechanical coupling factor(k$\sub$p/) Is showed the highest value of 0.622 at lmol% PSN and the mechanical quality factor(Q$\sub$m/) is decreased abruptly with the PSN substitution.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.272-273
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• 2007

In this study, in order to develop the composition ceramics of lead-free ultrasonic motor, (Na,Li)$NbO_3-BaTiO_3$ ceramics were fabricated using a conventional mixed oxide process and their piezoelectric and dielectric characteristics were investigated according to the $BaTiO_3$, substitution. $BaTiO_3$ substitution enhanced density, dielectric constants$({\varepsilon}_r)$ and electromechanical coupling factor$(k_p)$. However, mechanical quality factor was deteriorated. At the $BaTiO_3$ substitution of 4mol%, density, electromechanical coupling factor$(k_p)$, dielectric constants$({\varepsilon}_r)$ and piezoelectric constant$(d_{33})$ of specimen showed the optimum value of $4.493g/cm^3$, 0.236, 175, 70pC/N, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.59-61
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• 2005

In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, $Pb[(Mn_{1/3},Nb_{2/3})_{0.07}(Zn_{1/3}Nb_{2/3})_a(Zr_{0.48}Ti_{0.52})_{1-0.07-a}O_3]$ ceramics were manufactured with the variations of PZN from 2 to 14mol% and their dielectric and piezoelectric properties were investigated. Sintering temperature was varied from 910 to $1000^{\circ}C$. At 8mol% PZN substituted specimen sintered at $970^{\circ}C$, electromechanical coupling factor(kp), mechanical quality factor(Qm), dielectric constant and peizoelectric constant($d_{33}$) showed the optimal values of 0.536, 1803, 1551 and 328[pC/N), respectively, for multilayer piezoelectric transformer application.

• E2M - 전기 전자와 첨단 소재
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• 제10권9호
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• pp.901-908
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• 1997

The microwave dielectric properties of (Na.$_{1}$2//Sm$_{1}$2/)TiO$_3$and (Li$_{1}$2//Nd$_{1}$2/)TiO$_3$ceramics were investigated. Dielectric constant quality factor and temperature coefficient of resonant frequency of (Li$_{1}$2//Nd$_{1}$2/)TiO$_3$ceramics sintered at 145$0^{\circ}C$ for 2 hours were 86.2, 2780(at 3.8GHz) and 215ppm/$^{\circ}C$respectively. The solid solution of X(Na.$_{1}$2//Sm$_{1}$2/)TiO$_3$-(1-X)(Li$_{1}$2//Nd$_{1}$2/)TiO$_3$increased delectric constant and quality factor were decreased. Whereas temperature coefficient of resonant frequency was optimized to zero at the composition of 0.6(Li$_{1}$2//Sm$_{1}$2/)TiO$_3$-0.4(Li$_{1}$2//Nd$_{1}$2/)TiO$_3$where dielectric constant and quality factor were 86.2, 95-(at 3.8GHz) respectively. Also band-pass filters made of this material were examined.

• 마이크로전자및패키징학회지
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• 제18권3호
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• pp.39-43
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• 2011

마이크로파 유전체의 Q 값 측정에 널리 사용되고 있는 유전체 공진기 방법에서 캐비티의 재질변화가 유전체의 Q 값 측정에 미치는 오차요인에 대해 HFSS 시뮬레이션과 실측평가를 병행하여 조사하였다. HFSS의 전자계 벡터 형상으로부터 $TE_{01\delta}$ 모드의 공진주파수를 결정하고 $S_{21}$ 파라메터의 3dB 대역폭으로부터 Q 값을 계산하였다. 캐비티 금속이 Cu, SUS, Au 등으로 변화할 경우 유전체 공진기의 Q 값 측정에 큰 오차는 발생하지 않았으나, 금속이 산화하여 전도도가 수 천 정도로 떨어질 경우 Q 값이 매우 낮게 측정되는 오차가 발생함을 확인하였다. 이러한 시뮬레이션 결과는 실제로 다양한 재질의 금속 캐비티를 가지고 유전체 공진기의 Q 값을 측정해 본 결과 서로 일치되는 관련성을 나타내었다.