http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
오늘 본 자료
Microwave Dielectric Properties of (Pb0.4Ca0.6)[(Fe1/2Nb1/1)1-X(Mg1/3Nb2/3)X]O3 Ceramics
EungSooKim,KiMoonHan,JongHeeKim,KiHyunYoon 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.4
Microwave dielectric properties of (Pb0.4Ca0.6)[(Fe1/2Nb1/2)1-x(Mg1/3Nb2/3)x]O3 (PCFMN) ceramics were investigated as a function of (Mg1/3Nb2/3)4+ content (0.1x0.8). A single perovskite phase with the cubic structure was obtained through the given composition range. The unit cell volume was increased with (Mg1/3Nb2/3)4+ content, due to the larger average ionic size of (Mg1/3Nb2/3)4+ than that of (Fe1/2Nb1/2)4+ for B-site ion. Dielectric constant (K) and temperature coefficient of resonant frequency (TCF) of PCFMN ceramics were dependent on (Mg1/3Nb2/3)4+ content due to the decrease of ionic polarizability and B-site bond valence, respectively. Qf value was decreased with (Mg1/3Nb2/3)4+ content due to the decrease of grain size. Typically, K of 73.56, Qf of 5,074 GHz and TCF of -6.45 ppm/ oC were obtained for the specimens with x=0.4 sintered at 1250 oC for 3 hr.Corresponding author e-mail: eskim@kyonggi.ac.kr
Role of AIN Piezoelectric Crystal Orientation in Solidly Mounted Film Bulk Acoustic Wave Resonators
Si-HyungLee,SungChulKan,SangChulHan,ByungKwonJu,KiHyunYoon,Jeon-KookLee 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.4
To investigate the effect of AlN c-axis orientation on the resonance performance of film bulk acoustic wave resonators, solidly mounted resonators with crystallographically different AlN piezoelectric films were prepared by changing only the bottom electrode surface conditions. As increasing the degree of c-axis texturing, the effective electromechanical coupling coefficient ( ) in resonators increased gradually. The least 4 degree of full width at half maximum in an AlN (002) rocking curve, which corresponds to of above 5%, was measured to be necessary for band pass filter applications in wireless communication system. The longitudinal acoustic wave velocity of AlN films varied with the degree of c-axis texturing. The velocity of highly c-axis textured AlN film was extracted to be about 10200 m/s by mathematical analysis using Matlab.
Sang-HeeKwak,Tae-HyunYang,Chang-SooKim,KiHyunYoon 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.2
The performance evaluation on Pt loading in the self-humidifying polymer electrolyte membrane for polymer electrolyte membrane fuel cell (PEMFC) was investigated by using single cell test and measurement of membrane resistance. The self-humidifying membrane comprised two membranes made of perfluorosulfonylfluroride copolymer resin and fine Pt particles lying between them, coated by sputtering. From the results of performance characteristics of self-humidifying membrane cell with different Pt loading, a single cell using self-humidifying membrane with 0.15 mg/cm2 Pt loading showed better performance than that with the others over entire current density. Also, a single cell with 0.15 mg/cm2 Pt loading had a lower resistance value than the other cells under externally nonhumidifying condition. It is indicated that the water produced in the membrane cell with 0.15 mg/cm2 Pt loading showed a higher provision to maintain ionic conductivity of the membrane than the other cells. The optimum amount of Pt particles embedded in the membrane for self-humidifying PEMFC was determined to be about 0.15 mg/cm2.
Min-ChulKim,Ji-WonChoi,Chong-YunKang,Seok-JinYoon,Hyun-JaiKim,KiHyunYoon 한국전기전자재료학회 2002 Transactions on Electrical and Electronic Material Vol.3 No.1
The effects of substrate temperatures and annealing temperatures on the microstructures and ferroelectric properties of PbZr0.52Ti0.48O3 (PZT) thin films prepared by pulsed laser deposition (PLD) were investigated. For this purpose, the PZT films were deposited at various substrate temperatures (400∼600℃) with post annealing process in oxygen atmosphere. The single perovskite phase was formed at the deposition temperature of 500 to 550℃ without post annealing and the PZT films deposited below 500℃ formed the single phase with post annealing at 650℃. The grain size of the films increased and the grain boundary of the films was clearly defined as the substrate temperature increased from 400 to 550℃. The remnant polarization (Pr) and the coercive field (Ec) of the films deposited at 550℃ and annealed at 650℃ were 34.3 μC/cm2 and 60.2 kV/cm, respectively.