• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.972-975
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• 2001

The effect of Cr$_2$O$_3$(0 to 0.5 wt%) doping on the microstructure and electrical properties of ternary Pb(Zr,Ti)O$_3$-Pb(Ni,Nb)O$_3$piezoelectric ceramic has been investigated. Abnormal grain growth (grain size 3.3 to 11.2 $\mu$m) and densification are found. Minor additives of $\leq$0.1 wt% improve the mechanical coupling factor, but with more additives of $\geq$0.2 wt% electrical properties deteriorate. Thus, these phenomna can be ascribed mainly to anomalous developed microstructure. The large grains were composed of a core region that is free of Cr and a surrounding shell region rich in Cr. The interfaces between the core and the shell were composed of misfit dislocations. The mechanical properties of the specimens were strongly influenced by this microstructural change. The microstrutural and compositonal evolution of the specimens containing different amounts of Cr$_2$O$_3$were monitored. Electrical properties were measured and related to the variations in the microstructure.

• Journal of the Korean Ceramic Society
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• v.26 no.5
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• pp.670-676
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• 1989

The PbTiO3 is well known materials having remarkable ferroelectric, piezoelectric, and pyroelectric properties. PbTiO3 thin films with a perovskite structure were successfully fabricated on titanium substrate by chemical vapor deposition. These films were characterized according to composition, crystal structure, and electrical properties. Semi-quantitative compositional analysis of the deposited films was made by Auger Electron Spectroscopy(AES). The PbTiO3 film deposited on titanium substrate at the deposition temperature 75$0^{\circ}C$, the Ti(C2H5O)4 fraction 0.15, and O2 partial pressure 0.06atm, has a columnar structure and grows with(001) preferred orientation, and has stoichiometric composition. A clear dielectric transition and offset in the dc conductivity near the transition temperature(48$0^{\circ}C$) were observed in the deposited lead titanate film.

• Journal of radiological science and technology
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• v.23 no.2
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• pp.33-37
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• 2000

The authors fabricated ultrasonic transducer with PVDF[poly(vinylidene fluoride)] piezoelectric polymer film. When impulse waves were applied to the PVDF ultrasonic transducer, the dependence of the response properties on the backing material with copper was investigated through not only theoretical calculations using Mason's equivalent circuit but also experimental measurements. The experimental pulse response properties agree with those of the theoretical calculations and the pulses were shorter than those for a PZT transducer. If such short-pulse properties are used in an medical ultrasonic image diagnosis apparatus, the resolution of the apparatus will be improved. When the insertion loss was calculated theoretically to the PVDF ultrasonic transducer, the frequency characteristics of its showed wideband frequency.

• The Korean Journal of Ceramics
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• v.4 no.4
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• pp.352-355
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• 1998

Dense $ Pb(Zr, Ti)O_3(PZT)/Al_2O_3$ nanocomposites were prepared by the 28 GHz microwave heating method and conventional electric furnace sintering. Electrical and mechanical properties of the composites were investigated. The fracture strength of the PZT composites with 0.1vol% $Al_2O_3$ was significantly improved in both sintering methods. Smaller grain size and effective reinforcement of the PZT matrix by the second phase were considered to be responsible for the excellent fracture strength. Planar electromechanical coupling factor Kp of the composites sintered by 28GHz microwave heating was higher than that of the materical prepared by the conventional route. It seemed that the control of the reaction between PZT and $Al_2O_3$ by the microwave rapid sintering resulted in the high piezoelectric properties.

• Journal of the Korean Ceramic Society
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• v.45 no.11
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• pp.713-718
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• 2008

PSZT are selected and SHS are applied to each system. The sintering properties of PSZT powders showed $7.754g/cm^3$ of sintered density and $4{\mu}m$ of grain size at sintering temperature of $1250^{\circ}C$. Curie temperature lowered gradually from $363.6^{\circ}C\;to\;319.2^{\circ}C$ and relative dielectric constants increased rapidly by a quantity of Sr. This remarkable contrast in dielectric properties with powder preparation methods, in this study, was not due to grain size and sintered density but rather a crystallinity and sinterability of synthesized powders, extra-supplied Pb during reaction, mol fraction of rhombohedral phase and purity of starting materials.

• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.171-175
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• 2011

Lithium secondary batteries using lithium metal count electrode are easy to use and to analyze the specific characteristics of working electrode. Nevertheless, during the charge operation internal electrical short circuit could be caused by the dendritic growth of lithium. The cell failure by the short circuit depends on the condition of separator such as constitutive material and thickness. To prevent the cell failure caused by the dendritic growth of lithium, the electrochemical properties of the cell of lithium metal count electrode were evaluated for four different kinds of separator. Among the tested separators, GMF (glass micro-fiber filter, $300{\mu}m$) was the most promising one because it could effectively prevent the cell failure during the charge. The cell using GMF separator had relatively low impedance. Generally the cell using thicker separator than $50{\mu}m$ could effectively avoid the cell failure by internal short circuit and had the good cycleability. The highest rate capability by the signature method was acquired in the case of GMF separator.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.11a
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• pp.251-257
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• 1997

압전 바이몰프형 엑츄에이터에 진동판을 부착한 압전팬은 압전 바이몰프의 굴곡진동을 이용한 요동식 팬으로, 코일식 모타 팬에 비해 구조 및 풍량의 조절이 간단하고 미소량의 풍량 (1m/s)을 일으킬 수 있다. 또한 전자적인 잡음이 발생치 않는다. 수명이 재래 전자팬은5,000-10,000시간인데 비해 약 25,000시간으로 길며 압전체이기 때문에 대응한 전자석 로타리 팬 전력의 1/15mw이하의 저 소비전력을 갖는등의 잇점을 가지고 있다. (중략)

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.94.1-94.1
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• 2007

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.97.2-97.2
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• 2007

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.29.1-29.1
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• 2000