• Journal of Sensor Science and Technology
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• v.17 no.6
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• pp.418-424
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• 2008

The PZT based piezoelectric thick films prepared by screen printing method have been mainly used as a functional material for MEMS applications due to their compatibility of MEMS process. However the screen printed thick films generally reveal poor electrical and mechanical properties because of their porous microstructure. To improve microstructure we mixed attrition milled powder with ball milled powder of 0.01Pb$(Mg_{1/2}W_{1/2})O_3$-0.41Pb$(Ni_{1/3}Nb_{2/3})O_3$-$0.35PbTiO_3$-$0.23PbZrO_3$+0.1 wt% ${Y_2}{O_3}$+1.5 wt% ZnO composition. By mixing 25 % of attrition milled powder and 75 % of ball milled powder, the broadest particle size distribution was obtained, leading to a dense thick film with crack-free microstructure and improved dielectric properties. The X-ray diffraction analysis revealed that the film was in wellcrystallized perovskite phase. The remanent polarization was increased from $13.7{\mu}C/cm^2$ to $23.3{\mu}C/cm^2$ at the addition of 25 % attrition milled powder.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.9
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• pp.611-615
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• 1999

Piezoelectric properties of PMN-PZT ceramics with $CeO_2$ impurity were investigated. Mechanical quality factor, $Q_m$ of 1792, 1285 and the electromechanical coupling coefficient, $k_p$ of 0.52, 0.54 were obtained from the specimen with 0.25 and 0.5 mole % $CeO_2$ respectively. Curie temperature was decreased with the addition of $CeO_2$ while the electric coercive field was proportional to the amount of impurity. Based on the system ceramics with 0.5 mole % cerium oxide, a Rosen type piezoelectric transformer was fabricated and tested. Voltage step-up ratios of 230 and 13 were obtained from the transformer at no load and $100 k\Omega$ resistance, respectively. Experimental results showed a potential of the transformer for the practical use coupled with the expected strength increase by the grain size refinement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.357-360
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• 2000

Ferroelectric 0.05PZN-xPZT(90/10)-(0.95-x)PZT(10/90) (x=0.65, 0.85) specimens were fabricated by the mixed-oxide method and cold-pressing method using sol-gel derived PZT(90/10) and PZT(10/90) powders. All specimens show a uniform ferroelectric grain without the presence of the pyrocholre phase. Average grain size increased with an increase in sintering temperature, the value for the x=0.65 specimen sintered at 125$0^{\circ}C$ was 14.4${\mu}{\textrm}{m}$. The dielectric constant and dielectric loss of the x=0.65 specimen sintered at 125$0^{\circ}C$ were 1247, 2.05%, respectively. All specimens showed fairly good temperature and frequency stability of dielectric constant with the range from -2$0^{\circ}C$ to 6$0^{\circ}C$ and 100Hz to 10MHz. The coercive electric field and the remanent polarization of x = 0.65 specimen sintered at 125$0^{\circ}C$ were 8.5 kV/cm and 13 $\mu$C/cm$^2$, respectively.

• The Journal of the Petrological Society of Korea
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• v.13 no.4
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• pp.201-213
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• 2004

The Precambrian amphibolites in the central Gyeonggi massif, Yangsuri, Gyeonggido and southeastern Okcheon metamophic belt, Mungyeonggun, Gyeongsangbukdo, Korea, were studied on the geochemical characteristics of major and trace elements, and discussed petrogenetically and geotectonically. The characteristics of major elements of the amphibolites in these study areas are igeous origin such as tholeiitic-, subalkaline and alkaline basalt. Geotectonic distinction diagrams of trace elements such as Ti-Zr-Y and Zr-Nb-Y show basaltic igneous activity of island arc and mid ocean ridge environment at central Gyunggi massif, and within plate environment at southeastern Okcheon metamorphic belt. This result shows that genetic environments of study areas are different. Especially, origin of amphibolites in central Gyeonggi massif is similar with that of western Gyeonggi massif but different with the amphibolites of Chuncheon area. Genetic environment estimated of fractional crystallization of plagioclase has no particular effect on the origin of magma because value of LREE is higher than that of HREE and Eu anomaly definitely don't be exposed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.353-354
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• 2009

Tensile deformation behavior with different strain rate was investigated. $Zr_{56.2}Ti_{13.8}Nb_{5.0}Cu_{6.9}Ni_{5.6}Be_{12.5}$ (bulk metallic glass alloy possessed crystal phase which was called $\beta$-phase of dendrite shape, mean size of $20{\sim}30{\mu}m$ and occupied 25% of the total volume) was used in this study. Maximum tensile strength was obtained as 1.74Gpa at strain rate of $10^2/s$ and minimum strength was found to be 1.6GPa at $10^{-1}/s$. And then, maximum plastic deformation occurred at the strain rate of $5{\times}10^{-2}/s$ and represented 1.75%, though minimum plastic deformation showed 0%. In the specific range of strain rate, relatively higher plastic deformation and lower ultimate tensile strength were found with lots of shear bands. The fractographical observation after tensile test indicated that vein like pattern on the fracture surface was well developed especially in the above range of strain rate.

• Journal of the Korean Society of Safety
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• v.24 no.4
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• pp.22-27
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• 2009

In this paper, the minuteness structure, piezoelectric, and dielectric characteristics of $0.95{Pb(Sb_{1/2}Nb_{1/2})_{0.02})_{0.02}(Ni_{1/3}Nb_{2/3})_{0.13}(Zr_{0.48}Ti_{0.52})_{0.85}}O_3+0.05Pb(CO_{1/2}W_{1/2})O_3+0.3%$ $MnO_2+0.3wt%$ CuO ceramics has been systematically investigated as a function of the sintering temperature after manufacturing the specimens with a general method. This study will be very helpful as basic data for developing ceramic materials, More study in a soon time for improving stability of temperature, effect of adds and stability and reality of frequency with improved production condition for specimens will give a powerful potentiality as a applied material of dielectric ceramics.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.6
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• pp.619-627
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• 2004

Statement of problem. Mechanisms of tissue-implant interaction and the effect of the implant surface on the behavior of cells has not yet been clarified. Purpose. This study was performed to investigate the tissue reaction to the titanium alloy submerged into rat peritoneum in vivo. Materials and methods. Titanium alloys (titanium-13Zirconium-6Niobium) were inserted inside the peritoneal cavity of Sprague Dawley rats. After 3 months, the tissue formed around the inserted titanium alloys were examined with a light-microscope. Tissue reaction around the material was analyzed by confocal microscopy to evaluate their biocompatibility in a living body. Results. In in vivo study, foreign body type multinucleated giant cells were found in the fibrous tissue formed as a reaction to the foreign material (4 in 20 cases), but the inflammatory reaction was very weak. After experiment, the contaminants of biomaterials was removed from living tissue. In confocal microscopy, we observed that the staining of vinculin and actin showed mixed appearance. In a few cases, we found that the staining of vinculin and beta-catenin showed the prominent appearance. Conclusion. We found that titanium-13Zirconium-6Niobium alloy was an excellent biomaterial.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.6
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• pp.538-544
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• 2000

The laser patterning of sputter-deposited CoNdZr/Cu/CoNbZr multi-layered films had been tried using Nd:YAG laser. However generally it is very difficult to remove metal films because of their high reflectance of the laser on the surfaces. As a counterproposal for this problem authors for the first time tried to deposit energy-absorbing layers on the metal films and then irradiated the laser on the surfaces of energy-absorbing layers. Here the energy-absorbing layers consisted of laser energy-absorbing fine powders and binding polymers. Three kinds of powders for the energy-absorbing layers had been used to see the difference in the pattern formation with the degree of laser energy absorption. They were electrically conductive silver powders insulating BaTiO$_3$powder and semiconducting carbon powder. Remarkable difference in width of the formed pattern and the roughness of pattern edge were observed with the characteristic of the powder for the energy-absorbing layer. The pattern width using carbon paste was about three times larger than that using BaTiO$_3$paste. It was observed that the energy-absorbing layer with carbon was the most effective on this micro-patterning.

• Transactions of Materials Processing
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• v.18 no.6
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• pp.500-507
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• 2009

Tensile deformation behavior with different strain rate was investigated. $Zr_{56.2}Ti_{13.8}Nb_{5.0}Cu_{6.9}Ni_{5.6}Be_{12.5}$(bulk metallic glass alloy possessed crystal phase which was called $\beta$-phase of dendrite shape, mean size of $20{\sim}30{\mu}m$ and occupied 25% of the total volume) was used in this study. Maximum tensile strength was obtained as 1.74GPa at strain rate $10^2s^{-1}$ and minimum strength was found to be 1.6GPa at $10^{-1}s^{-1}$. And then, maximum plastic deformation occurred at the strain rate of $5{\times}10^{-2}s^{-1}$ and represented 1.75%, though minimum plastic deformation showed 0%. In the specific range of strain rate, relatively higher plastic deformation and lower ultimate tensile strength were found with lots of shear bands. The fractographical observation after tensile test indicated that vein like pattern on the fracture surface was well developed especially in the above range of strain rate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.796-801
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• 2001

Ferroelectric 0.05PZN-xPZT(90/10)-(0.95-x)PZT(10/90) (x=0.65, 0.85) specimens were fabricated by the solid-state reaction method, and especially PZT(90/10) and PZT(10/90) powders were derived by the sol-gel method. All specimens showed a uniform ferroelectric grain without the presence of the pyrocholre phase. Average grain size increased with an increased in sintering temperature, the values for the x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 14.4$\mu$m and 9.8$\mu$m, respectively. The dielectric constant and dielectric loss of the x=0.65 specimen sintered at 125$0^{\circ}C$ were 1247. 2.06%, respectively. The coercive field and the remanent polarization of x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 8.5kV/cm, 13$\mu$C/$\textrm{cm}^2$ and 17.2kV/cm, 28 $\mu$C/$\textrm{cm}^2$, respectively. The pyroelectric coefficient of the x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 5.64$\times$10$^{-8}$ C/$\textrm{cm}^2$K and 2.76$\times$10$^{-8}$ C/$\textrm{cm}^2$K, respectively.