• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.2
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• pp.77-81
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• 2002

In this study, PZT thin films were fabricated using sol-gel processing onto Si/$SiO_2$/Ti/Pt substrates. PZT sol with different Zr/Ti ratio(20/80, 30/70, 40/60, 52/48) were prepared, respectively. The films were fabricated by using the spin-coating method on substrates. The films were heat treated at $450^{\circ}C$, $650^{\circ}C$ by rapid thermal annealing(RTA). The preferred orientation of the PZT thin films were observed by X-ray diffraction(XRD), and Scanning electron microscopy(SEM). All of the resulting PZT thin films were crystallized with perovskite phase. The fine crystallinity of the films were fabricated. Also, we found that the ferroelectric properties from the dielectric constant of the PZT thin films were over 600 degrees, P-E hysteresis constant. And the leakage current densities of films were lower than $10^{-8}A/cm^2$. It is concluded that the PZT thin films by sol-gel process to be convinced of application for ferroelectric memory device.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1061-1067
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• 2004

In this study, ferroelectric (Ba,Sr)TiO$_3$ and high temperature superconductor YBCO thin films were fabricated by PLD (Pulsed Laser Deposition) method and tuneable bandstop filters were implemented with two different IDC(Interdigital Capacitance) gap patterns, 20${\mu}{\textrm}{m}$ and 30${\mu}{\textrm}{m}$ using these two thin film layers. The resonant frequency was changed by DC bias voltage. By comparing measured results with simulation, the dielectric properties of ferroelectric thin film have been extracted. The permittivity was 820 ～ 900 at 30 K and had an acceptable error range but the loss tangent had a great difference, 0.018 in 30${\mu}{\textrm}{m}$ IDC gap pattern and 0.037 in 20 ${\mu}{\textrm}{m}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1118-1122
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• 2006

In this study, in order to develop the low temperature sintering multilayer piezoelectric actuator, PMN-PNN-PZT system ceramics were manufactured and their microstructure, ferroelectric and piezoelectric properties were investigated. By increasing sintering temperature, remanent polarization$(P_r)$ was increased due to the increase of sinterability and grain size. However, coercive $field(E_c)$ showed an opposite tendency to remanent polarization owing to the feasibility of domain wall motion. At the sintering temperature of $900^{\circ}C$, dielectric $constant({\varepsilon}_r)$, electromechanical coupling $factor(k_p)$, piezoelectric $constant(d_{33})$ and mechanical quality $factor(Q_m)$ showed the optimal value of 1095, 0.60, 363 and 1055, respectively, for multilayer piezoelectric actuator application.

• Transactions on Electrical and Electronic Materials
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• v.11 no.4
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• pp.182-185
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• 2010

$Pb_{0.99}[(Zr_{0.6}Sn_{0.4})_{0.9}Ti_{0.1}]_{0.98}Nb_{0.02}O_3$ (PNZST) thin films were deposited by radio frequency magnetron sputtering on a $(La_{0.5}Sr_{0.5})CoO_3$ (LSCO)/Pt/Ti/$SiO_2$/Si substrate using a PNZST target with an excess PbO of 10 mole%. The thin films deposited at the substrate temperature of $500^{\circ}C$ crystallized to a perovskite phase after rapid thermal annealing (RTA). The thin films, which annealed at $650^{\circ}C$ for 10 seconds in air, exhibited good crystal structures and ferroelectric properties. The remanent polarization and coercive field of the fabricated PNZST capacitor were approximately $20uC/cm^2$ and 50 kV/cm, respectively. The reduction of the polarization after $2.2\;{\times}\;10^9$ switching cycles was less than 10%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.48-51
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• 1997

(Pb. La)TiO$_3$ thin films were fabricated by sol-gel Processing and spin-coated on the Pt substrate. The spin-coated PLT films were sintered at 75$0^{\circ}C$ for 5min by rapid thermal ann La content dependence of the electrical properties of the PLT thin films are discussed. Wit La mole% from 20 to 36mo1e%. the dielectric constant of the PLT thin films decreased f 570. P-E hysteresis loops changed from ferroelectric to paraelectric. and the charge storage charging time decreased. The Curie Point decreased with increasing La content. The leak density also decreased and La 36mo1% species shows mood characteristics less than 10- electric field 500 (KV/cm) Because of the broad range of composition-controlled ferroelectric PLT thin films are suitable for memory application.

• Transactions on Electrical and Electronic Materials
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• v.6 no.5
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• pp.210-213
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• 2005

The $BaTiO_3/SrTiO_3$ heterolayered thick films were fabricated by the screen printing method on alumina substrates. The effect of the sintering temperature on the microstructure and dielectric properties of the $BaTiO_3/SrTiO_3$ thick films has been investigated. The relative dielectric constant and dielectric loss at 1 MHz of the $BaTiO_3/SrTiO_3$ heterolayered thick films with sintering temperature of $1350^{\circ}C$ were about 751 and 1.74, respectively. The remanent polarization $(P_r)$ of the pure $(Ba_{0.5}Sr_{0.5})TiO_3$ and $BaTiO_3/SrTiO_3$ heterolayered films are approximately $5.1\;{\mu}C/cm^2$ and $10\;{\mu}C/cm^2$. This study suggests that the design of the $BaTiO_3/SrTiO_3$ heterolayered thick films capacitor with different phase should be an effective method to enhance the dielectric and ferroelectric performance in devices.

• Elastomers and Composites
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• v.56 no.2
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• pp.57-64
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• 2021

This paper reviews recent developments and applications of dielectric elastomers (DEs) and suggests various techniques to improve DE properties. DEs as smart materials are a variety of electro-active polymers (EAPs) that convert electrical energy into mechanical energy and cause a large deformation when a voltage is applied. The dielectric constant, modulus, and dielectric loss of DEs determine the efficiency of deformation. Among these, the dielectric constant significantly affects their performance. Therefore, various recent approaches to improve the dielectric constant are reviewed, including the enhancement of polarization, introduction of microporous structures in the matrix, and introduction of ferroelectric fillers. Furthermore, the basic principles of DEs are examined, as well as their various applications such as actuators, generators, sensors, and artificial muscles.

• Korean Journal of Crystallography
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• v.12 no.2
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• pp.65-91
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• 2001

Errors and its compensation in the measurement of dielectric hysteresis in ferroelectric by using Sawyer-Tower circuit were discussed. When ferroelectrics are lossy, remanent polarization and coercive field are likely to be over-estimated. As the DC conductivity and measuring time increases, measurement errors in ferroelectric properties increase. Current hysteresis measurement was suggested for compensation such errors.

• Electrical & Electronic Materials
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• v.7 no.5
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• pp.369-375
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• 1994

In this study, ferroelectric thin films of PZT with different Zr/Ti ratio were prepared by sol-get processing and annealed by rapid thermal annealing at >$500^{\circ}C$>$-700^{\circ}C$ for 10 sec. -1 min. Structures of the annealed films were examined by X-ray diffraction and SEM. Thin films of PZT with perovskite structure have been obtained by annealing at >$600^{\circ}C$ or above and for 20 seconds or longer. Maximum remnant polarization of 10.24.mu.C/cm$^{2}$ and minimum coercive field of 20.06 kV/cm were obtained from the 56/44 and 65/35 Zr/Ti composition films, respectively. Dielectric constant, .epsilon.$_{r}$ of 500-1300 and dielectric loss, tan .delta., of 0.01-0.035 were obtained from the films.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.723-727
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• 2003

[ $Sr_xBa_{1-x}Nb_2O_6$ ] (SBN, $0.25{\leq}x{\leq}0.75$) ceramic is a ferroelectric material with tetragonal tungsten bronze (TTB) type structure, which has a high pyroelectric coefficient and a nonlinear electro-optic coefficient value. In spite of its advantages, SBN has not been investigated well compared to other ferroelectric materials with perovskite structure. In this study, SBN thin film was manufactured by ion beam sputtering technique using the prepared SBN target in $Ar/O_2$ atmosphere. SBN30 thin film of $1000{\AA}$ was pre-deposited as a seed layer on $Pt(100)/TiO_2/SiO_2/Si$ substrate followed by SBN60 deposition up to $3000{\AA}$ in thickness. As-deposited SBN60/SBN30 layer was heat-treated at different temperatures of 650, 700, 750, and $800^{\circ}C$ in air, respectively The crystallinity and orientation behavior as well as electric properties of SBN60/SBN30 multi-layer were examined. The deposited layer was uniform and the orientation was shown primarily along (001) plane from XRD pattern. There was no difference in the crystal structure with heat-treatment temperature, but the electric properties depended on the heating temperature and was the best at $750^{\circ}C$. In electric properties of Pt/SBN60/SBN30/Pt thin film capacitor prepared, the remnant polarization (2Pr) value was $15{\mu}C/cm^2$, the coercive field (Ec) 75 kV/cm, and the dielectric constant 1075, respectively.