• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 제2회 학술대회 논문집 일렉트렛트 및 응용기술전문연구회
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• pp.15-20
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• 2000

In this paper. Thermally Stimulated Current spectra have been measured in the Polypy - romellitimide (polyimide). As a result of the investigation. three peaks have been observed: $A(50^{\circ}C)$, $B(120^{\circ}C)$, $C(200^{\circ}C)$. Among three peaks, C peak has been observed in detail. The C peak is shown to be created due to the polarization of ionic space charge from the experimental results which were measured as a function of forming time, forming temperature. forming voltage and collecting voltage. As a result, we have measured the TSC in ion ($Na^+$) implanted - Polyimide, also found the peak at $215^{\circ}C$. Therefore, TSC characteristics in the C peak is probably caused by residual impurity. And The activation energy caculated by means of initial rising method 1.8eV, hopping distance. $90{\AA}$. and the mobility. $2.88{\times}10^{-11}cm^2/v.s$

• 대한전기학회논문지
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• 제34권4호
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• pp.144-152
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• 1985

This paper temperature gradient thermally stimulated surface potentian (TG-TSSP) in measurements are applied to the study of the polarity of trapped and ionic carriers in cross-linked polyethylene (XLPE) filsm. In the thermally stimulated current in uniform temperature (TSC) of XLPE five peaks appear as indicated of the A B C D and E. In this paper A (at about -120$^{\circ}C$) D (at about 70$^{\circ}C$) and E (at about 110$^{\circ}C$) peaks are investigated. A peak is due to the biassing voltage and biassing temperature. Appear in to the glass transition temperature territory and caused in to the polarization of dipole. D peak is due to the depolarization of ionic space charge and E peak due to the detrapping of carriers injected from the electrodes. TG-TSSP and TSSP are measured to study the polarity of ionic carrier (D peak). In the unsatureated region of ionic space charge polarization, TG-TSSP is lower than TSSP during the initial stage of heating. Result of the experiment for E peak, TG-TSSP is higher than TSSP during the initial stage of heating and these results do not depend on the polarity of biassing voltage, and E peak is concerned with positive carriers (Holes).

• 한국세라믹학회지
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• 제20권4호
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• pp.315-323
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• 1983

Effect of NiO and $MnO_2$ addtivies on the dielectric piezoelectrics and polarization-reversal properties of $(Pb_{0.936} La_{0.064})$$(Zr_{0.60}Ti_{0.40})O_3$ ceramics have been investigated. The specimens were prepared by the mixed oxide techni-que and atmosphere sintering method. The room temperature X-ray diffraction studies show that perfect perovskite solution with tetragonal structure was obtained from PLZT and its additives. The dielectric constant and dissipation factor decreased with the addition of both NiO and $MnO_2$ The Curie of Curie temperature was not observed but they displayed broadened maxima. The planar coupling factor was improved by addition of NiO and also increased with increasing sintering time carried out at 105$0^{\circ}C$ Addition of $MnO_2$ yielded a markedly high mechanical quality factor. The space-charge field decreased with the addition of NiO but increased with the addition of $MnO_2$ The planar coupling factor and space-charge field showed same dependence on the additivies. The tetragonality Curie temperature and planar coupling factor of $(Pb_{0.936} La_{0.064})$$(Zr_{0.60}Ti_{0.40})O_3$ were higher than those of $(Pb_{0.936} La_{0.064})$$(Zr_{0.568}NU_{0.032}Ti_{0.40})_{0.984}O_3$ but the grain size lattic parameter dielectric constant dissipation factor mechanical quality factor and space-charge field of the former were lower than those of the latter.

• 한국재료학회지
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• 제11권3호
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• pp.207-214
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• 2001

실리카 유리는 매우 우수한 광도파 소재이지만 비선형 광특성이 거의 없다. 그러나 이런 실리카 유리에 금속 전극과 같은 차단전극을 이용하여 강한 전기장을 장시간 가하게 되면 공간 전하 분극이 발생하게 되고 이에 의해 비선형 광특성이 나타나게 된다는 것은 실험적으로 알려져 왔다. 본 연구에서는 전기분극 시 실리카 유리에서 나타나는 비선형 광특성의 경시적인 변화를 공간적인 위치와 시간에 따라 정확히 예측할 수 있는 수치해석적인 모델을 제시하고자 하였다. 이를 위해서 지금가지 실험들에서 실리카 유리의 비선형 광특성 발생의 원인으로 밝혀진 공간전하분극을 전기분극 기구의 전산모사를 통하여 규명하였다. 비정질 실리카를 전해질 용액과 같은 특성을 지니는 매질로 가정하고 전하운반체가 단지 $Na^{+}$ 밖에 없다는 가정 하에 유한 차분법 (finite difference method)을 이용하였다. 원래의 복잡한 함수들을 표준화 변수들을 이용하여 간단한 식으로 변환하여 $Na^{+}$의 농도와 전기장의 분포를 표준화된 시편의 길이와 인가된 전압의 세기만으로 구할 수 있도록 하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.229-230
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• 2008

The investigations included the measurements of volume currents and also internal space charges on epoxy samples of mm thicknesses. The current versus time relations were shown to correspond well with classical forms of dielectric response such as the Curie-von Schweidler model. After the time transient, near steady currents were extremely small and exhibited a significant temperature dependence, similar in relation to the Poole-Frenkel hoping transport model. Equivalent resistances were on the order of $10^{19}$ ohms and represent very weak charge transport. Electrically stimulated acoustic waves were used to quantify the small internal charges that would accumulate within the epoxy. There was a notable homocharge near both anode and cathode. The dielectric response and the internal charge were related to show a consistent model for charge transport within unfilled epoxy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.2311-2312
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• 2008

The investigations included the measurements of volume currents and also internal space charges on epoxy samples of mm thicknesses. The current versus time relations were shown to correspond well with classical forms of dielectric response such as the Curie-von Schweidler model. After the time transient, near steady currents were extremely small and exhibited a significant temperature dependence, similar in relation to the Poole-Frenkel hoping transport model. Equivalent resistances were on the order of 1019 ohms and represent very weak charge transport. Electrically stimulated acoustic waves were used to quantify the small internal charges that would accumulate within the epoxy. There was a notable homocharge near both anode and cathode. The dielectric response and the internal charge were related to show a consistent model for charge transport within unfilled epoxy.

• 한국세라믹학회지
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• 제29권1호
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• pp.65-73
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• 1992

The effect of grain size on the time-dependent piezoelectrice degradation of a poled PZT of MPB composition Pb0.988Sr0.012 (Zr0.52Ti0.48)O3 with 2.4 mol% of Nb2O5 was studied, and the degradation mechanism was discussed. Changes in the internal bias field and the internal stress both responsible for the time-dependent degradation of poled PZT were examined by the polarization reveral technique, XRD and Vickers indentation, respectively. The piezoelectric degradation increased with increasing time and grain size, and the internal bias field due to space charge diffusion decreased with increasing grain size of poled PZT. The internal bias field, however, was almost insensitive to the degradation time regardless of the grain size. On the other hand, both the x-ray diffraction peak intensity ratio of (002) to (200) and the fracture behavior including the crack propagation support that the ferroelectric domain rearrangement of larger grain size showed rapid relaxation of the internal stress compared with smaller one, which is thought the origin of the larger piezoelectric degradation in the former. In conclusion, the contribution of space charge diffusion on the piezoelectric degradation of PZT is strongly dependent on both the grain size and the composition. Thus, the relaxation of internal stress due to the ferroelectric domain rearrangement as well as the amount and time-dependence of the internal bias field due to space charge diffusion should be considered simultaneously in the degradation mechanism of PZT.

• The Korean Journal of Ceramics
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• 제6권3호
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• pp.267-271
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• 2000

The influence of photoexcited nonequilibrium carriers on domain switching and photovoltaic current was investigated in two kinds of poled La-modified PbTiO$_3$ferroelectric ceramics, (Pb$_{0.85}$La$_{0.15}$)TiO$_3$and (Pb$_{0.76}$La$_{0.24}$)TiO$_3$, under illumination in the absence of external electric field. Both photovoltaic current and cumulative AE event counts increased with illumination time. The observed nonsteady-state photovoltaic current could be explained on the basis of the cycles of a series of physical events consisting the establishment of space charge field by photoexcited carriers trapped at the grain boundaries, the photoinduced domain switching, and the increase in the remanent polarization. An analysis of energy distribution of the observed AE signals also revealed that the space charge field in (Pb$_{0.85}$La$_{0.15}$)TiO$_3$allowed both 18$0^{\circ}C$ and 90$^{\circ}$domains to be switched during illumination.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.413-416
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• 1996

The ceramic dielectrics were fabricated by mixing of Mn $O_2$ and ZnO at (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_3$ and studied for dielectric relaxation characteristics. The dielectric relaxation time was increased by space charge polarization of palaelectric layer at the low temperature and frequency but it was decreased by Interface polarization at the high temperature and frequency. The remnant polarization and coercive field of ceramic dielectrics was decreased by rising temperature.ure.

• 한국전기전자재료학회논문지
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• 제11권12호
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• pp.1108-1114
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• 1998

$BaTiO_3$ thin films preferred c-axis orientation for the potential application of ferroelectric memory devices were deposited on silicon substrates(100) by RF sputtering and annealed at 800 and 900[$^{\circ}C$] in air. The BT(100)/BT(110) peak ratio of the sputtered sample was decreased with post-annealing in air. According to increasing with annealing temperature and time, the peak ratio of BT(100)/BT(110) was decreased and the surface density of thin film was high. Dielectric characteristics of $BaTiO_3$ thin film was measured as a function of annealing temperature and frequency. The dielectric constants were increased with annealing and decreased with frequency by space charge polarization and dipole polarization below 600[kHz]. The remanent polarization and coercive field in P-E hysteresis loop of $BaTiO_3$thin film were increased with the annealing temperature in air. The remanent polarization and coercive filed annealed at 800[$^{\circ}C$] for 1hr were 1.2[$\mu$C/$cm^2$] and 200[kV/cm]