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Im I.-H.,Korea University | Chung K.-H.,Kyungwon Industry Co. | Kim D.-H.,Korea Advanced Institute of Science and Technology
Transactions on Electrical and Electronic Materials | Year: 2014

Pb(Zr0.52Ti0.48)O3 thin films of 1.5 μm thickness were grown on Pt/Ti/Gd3Ga5O12 substrate by RF magnetron sputtering at annealing temperatures ranging from 550℃ to 700℃. We evaluated the residual stress, by using a William-Hall plot, as a function of the annealing temperatures of PZT thin film with a constant thickness. As a result, the residual stresses of PZT thin film of 1.5 μm thickness were changed by varying the annealing temperature. Also, we measured the hysteresis characteristic of PZT thin films of 1.5 μm thickness to evaluate for application of an optoelectronic device. ©2014 KIEEME. All rights reserved. Source


Bae S.-G.,Incheon National University | Shin H.-G.,Incheon National University | Chung K.-H.,Kyungwon Industry Co. | Yoo J.-H.,Semyung University | Im I.-H.,Korea University
Transactions on Electrical and Electronic Materials | Year: 2015

The particle sizes of 0.95(K0.5 Na0.5)NbO3 -0.05BaTiO3 powder were controlled by secondary milling time after calcination. The average particle sizes, Dmean, of 0.95(K0.5 Na0.5)NbO3 -0.05BaTiO3 powders were critically changed from 14.31 µm to 0.91 µm by secondary milling time. The dielectric and piezoelectric properties of 0.95(K0.5Na0.5)NbO30.05BaTiO3 ceramics depended on the particle sizes of powders after calcination and the secondary milling process. As secondary milling times after calcination were increased to more than 48 hr, the dielectric and piezoelectric properties of 0.95(K0.5Na0.5)NbO3-0.05BaTiO3 ceramics were deteriorated. ©2015, KIEEME. All rights reserved. Source


Im I.-H.,Korea University | Chung K.-H.,Kyungwon Industry Co.
Journal of Nanoscience and Nanotechnology | Year: 2014

We have investigated the dielectric and piezoelectric properties of lead-free 0.5Ba(Zr0.2Ti0.8)O3- 0.5(Ba0.7Ca0.3)TiO3 ceramics with BaO-CaO-SiO2 glass additive as a function of sintering temperatures. With adding BaO-CaO-SiO2 glass additive, diffusivity of lead-free 0.5Ba(Zr0.2Ti0.8)O3- 0.5(Ba0.7Ca0.3)TiO3 ceramics was increased. The dispersion constant of BZT-BCT ceramics with BaO-CaO-SiO2 glass was changed from 1.9683 to 1.7673 by decreasing sintering temperature ranging from 1450 °C to 1350 °C, while 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics at sintered 1450 °C showed = 1.5055. The piezoelectric properties such as electromechanical coupling factor (kp) and piezoelectric constant (d33) of lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics with BaO-CaO-SiO2 glass additive sintered at 1400 °C showed similar values compared with 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics without BaO-CaO-SiO2 glass additive sintered at 1450 °C. The addition of BaO-CaO-SiO2 glass additive can be of help to decrease sintering temperature of lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramics. Copyright © 2014 American Scientific Publishers All rights reserved. Source


Han J.S.,Korea University | Chung K.H.,Kyungwon Industry Co. | Bollina R.,Mahindra Ecole Centrale | Kim K.,Agency for Defense Development | And 3 more authors.
Ceramics International | Year: 2015

Abstract The sintering behavior of Pb(Al0.5Nb0.5)O3-Pb(Zr0.52Ti0.48)O3 (PAN-PZT) ceramics was investigated. The sintering process of PAN-PZT was divided into four stages based on the amount of in-situ linear shrinkage: (Stage 1) initial stage at sintering temperature RT≤Ts≤ to 770°C, (Stage 2) perovskite formation stage at 770≤Ts≤990°C, (Stage 3) densification stage at 990≤Ts≤1265°C and (Stage 4) Pb-loss stage at Ts>1265°C. During stage 1, heating of PAN-PZT compact did not cause structural changes except the thermal expansion. During stage 2, the PZT-perovskite structure was formed by rearrangement of crystals. During stage 3, the specimen was rapidly densified with two peaks of strain rate. During stage 4, Pb was volatilized and this loss resulted in sudden increase of shrinkage. On analyzing the sintering stages, the optimized sintering conditions were considered as 1250°C just before of Pb-loss stage. The effects of Ts on the crystal structure, microstructure and the piezoelectric performance were analyzed and documented. © 2015 Elsevier Ltd and Techna Group S.r.l. Source

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