• 한국세라믹학회지
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• 제51권6호
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• pp.591-597
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• 2014

A poled lead zirconate titanate (PZT) rectangular parallelepiped specimen was subjected to through-thickness electric fields at five loading rates and four temperatures. The rates of the electric field were 0.01, 0.10, 0.25, 0.50, and $1.00MVm^{-1}s^{-1}$; the temperatures were 20, 50, 80, and $110^{\circ}C$. From the measured polarization hysteresis responses, the so-called reference remnant polarization and strains were calculated. Using the calculated reference remnant polarization hysteresis loops, the effects of loading rates and temperature were discussed; using the calculated reference remnant strains, strain butterfly loops were calculated and compared with observations.

• 한국재료학회지
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• 제12권1호
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• pp.75-81
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• 2002

The ferroelectric properties of Pb(Zr,Ti)O$_3$[PZT] films degrade when the films with Pt top electrodes are annealed in hydrogen containing environment. This is due to the reduction activity of atomic hydrogen that is generated by the catalytic activity of the Pt top electrode. At the initial stage of hydrogen annealing, oxygen vacancies are formed by the reduction activity of hydrogen mainly at the vicinity of top Pt/PZT interface, resulting in a shift of P-E (polarization-electric field) hysteresis curve toward the negative electric field direction. As the hydrogen annealing time increases, oxygen vacancies are formed inside the PZT film by the inward diffusion of hydrogen ions, as a result, the polarization degrades significantly and the degree of P-E curve shift decreases gradually. The direction and the magnitude of the remnant polarization in the PZT film affect the motion of hydrogen ions which determines the degradation of polarization characteristics and the shift in the P-E hysteresis curve of the PZT capacitor during hydrogen annealing. When the remnant polarization is formed in the PZT film by applying a pre-poling voltage prior to hydrogen annealing, the direction of the P-E curve shift induced by hydrogen annealing is opposite to the polarity of the pre-poling voltage. The hydrogen-induced degradation behavior of the PZT capacitor is also affected by the internal field that has been generated in the PZT film by the charges located at the top interface prior to hydrogen annealing.

• 한국세라믹학회지
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• 제50권1호
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• pp.82-86
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• 2013

A poled lead zirconate titanate (PZT) cube specimen is subjected to impulse-type compressive stress with increasing magnitude in parallel to the poling direction at four room and high temperatures. During the ferroelastic domain switching induced by the compressive stress, electric displacement in the poling direction and longitudinal and transverse strains are measured. Using the measured responses, linear material properties, namely, the piezoelectric and elastic compliance coefficients, are evaluated by a graphical method, and the effects of stress and temperature are analyzed. Finally, the dependency of the evaluated linear material properties on relative remnant polarization is analyzed and discussed.

• 전기전자학회논문지
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• 제26권2호
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• pp.329-332
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• 2022

본 논문에서는 ferroelectric(HfO₂)구조가 적용된 3D NAND flash memory의 parameter에 따른 lateral charge migration의 retention과 V_th를 분석하였다. P_s가 클수록 Program 시 ferroelectric에서 가능한 최대 polarization이 크기 때문에 초기 V_th는 P_s 25µC/cm² 보다 P_s 70µC/cm²에서 약 1.04V차이로 커진다. 또한 Program 이후 trap된 전자는 시간이 지남에 따라서 lateral charge migration이 발생한다. Program 이후 gate에 전압을 가하지 않고 ferroelectric은 polarization을 유지하기 때문에 P_s와 크게 관계없이 P_r이 클수록 polarization이 커지고 lateral charge migration에 의한 ∆V_th는 P_r 5µC/cm² 보다 P_r 50µC/cm²에서 약 1.54V차이로 작아진다.

• E2M - 전기 전자와 첨단 소재
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• 제10권3호
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• pp.239-246
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• 1997

The ZnO is stabilize dielectric constant over a broad temperature range because its addition makes the relaxation time short. In this study, the composite oxide material (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_{3}$ was mixed by ZnO additive material and the dielectric polarization characteristics was studied. The relative density was over 90[%] at all specimen in the structural characteristics. Among of the specimen, the relative density of (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_{3}$ with ZnO (0.4mol) has a 95[%]. The grain size of composite oxide material with an increasing ZnO increased and it was 1.0[.mu.m]-1.22[.mu.m]. In the electrical characteristics, the charge and discharge current was increased by ZnO addition. The dielectric relaxation time was increased by space charge polarization at above 110[.deg. C] and the dielectric relaxation time was fixed by space charge polarization of para-dielectric layer at below 110[.deg. C]. The dielectric relaxation time was maximum when the grain size was small. The dielectric relaxation time is decreased with an additive material ZnO and interface polarization, existing void at the grain and grain boundary. The remnant polarization is increased and the coercive electric field is decreased by ZnO.

• 대한전기학회논문지
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• 제45권4호
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• pp.553-557
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• 1996

Heat cycle aging of insulating materials in large generator stator winding has been investigated using both on-line and off-line test methods. On this study, principally, off-line test against actual generator in service was carried out to acquire information about polarization index(PI) and dissipation factor, dissipation factor tip-up, maximum partial discharge for the purpose of remnant breakdown voltage and life assessment. It was found from the tests that both dissipation factor and maximum partial discharge decreased with the increase of operating hours and starting numbers. It was found from off-line tests that the remnant breakdown voltage had a strong relationship with both dissipation factor and maximum partial discharge the remnant breakdown voltage as a results of both operating hours and starting number and the nondestructive tests were proposed as parameters which can predict the remnant lifetime of insulating materials in large generator stator windings. (author). 8 refs., 8 figs., 2 tabs.

• 천문학회지
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• 제21권2호
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• pp.133-153
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• 1988

Linear polarization has been measured for fifteen extragalactic radio sources in the field of supernova remnant S 147. These observations were made at 4885, 4835, 1665, 1515, 1465, and 1385 MHz using the Very Large Array, primarily to determine unambiguous Rotation Measures (RM) of the sources. This yields a total of 11 new RM sources. Comparisons of a sample of sources which are seen through S 147 were made with sources located farther away. The result tentatively indicates that the distribution of the rotation measure of the former population is broadened, with more than a 85% level of confidence. This constitutes evidence that there is a SNR contribution to rotation measure in sources seen through the SNR. Limits on this RM contribution are statistically at 30 < | RM | < 70 rad $m^{-2}$ with a 85% statistical level of confidence. These result imply the magnetic field in the rim of S 147 has strength 10 microguass if the electron density is $1\;cm^{-3}$.

• 한국세라믹학회지
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• 제54권3호
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• pp.235-242
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• 2017

Changes in polarization and thermal expansion coefficients during temperature increase of a poled lead zirconate titanate (PZT) cube specimen switched by an electric field at room temperature are measured. The measured data are analyzed to construct governing differential equations for polarization and strain changes. By solving the differential equations, an experimental formula for the high temperature behavior of ferroelectric materials is obtained. It is found that the predictions by the formula are in good agreement with measures. From the viewpoint of macroscopic remnant state variables, it appears that the processes of electric field-induced switching at different temperatures are identical and independent of temperature between $20^{\circ}C$ and $110^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.50-53
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• 2002

YMnO$_3$ thin films were spun-coated on the Pt/Ti/SiO$_2$/Si substrates by sol-gel process using alkoxides, and then dried on hot plates from 300 to 450 $^{\circ}C$. The prepared YMnO$_3$ thin films were annealed at 850 $^{\circ}C$ in O$_2$ atmosphere for 1 h. The crystallization of YMnO$_3$ thin films were improved to preferred c-axis orientation and the dielectric characteristics were progressed by increasing the drying temperature. The range of dielectric constant of thin film dried at 450 $^{\circ}C$ is 12.9-22.3 and close to that of YMnO$_3$ single crystal. The ferroelecrtic property of YMnO$_3$ thin film was observed on the YMnO$_3$ films. The maximum remnant polarization (2Pr) of YMnO$_3$ thin films dried at 450 $^{\circ}C$ was about 2.91 ${\mu}$ C/cm2. It was suggested that the drying temperature affect to the initial stage of thin film growth of preferred c-axis orientation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.641-643
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• 2003

The ferroelectric properties of PZT(53/47) thin film was investigated by methoxy enthanol solution based on sol-gel method. The thickness of each layer by spincoating 0.25M sol at one time was $0.1{\mu}m$ and crack-free film was formed. $LaNiO_3/Si(100)$ electrode and $Pt/Ti/SiO_2/Si(100)$ electrode was coated by PZT sol at several times. PZT orientation was confirmed as a method of XRD and coercive field(Ec) as well as remnant polarization(Pr) was investigated from hysterisis curve. As a result of XRD analysis, we can know that the orientation of on PZT/LNO/Si(100) is better than on $Pt/Ti/SiO_2/Si(100)$. The remnant polarization(Pr) in LNO electrode was $87.5{\mu}C/cm^2$ and $39.8{\mu}C/cm^2$ in Pt. From this figures, it is investigated that the Pr in LNO electrode was better than in Pt.