• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.983-989
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• 2005

[ $PZT(Pb(Zr,Ti)O_3)$ ] thin films were deposited by multi-target reactive sputtering method on $RuO_2$ substrates. Pure perovskite phase PZT films could be obtained by introducing Ti-oxide seed layer on the $RuO_2$ substrates prior to PZT film deposition. The PZT films deposited on the $RuO_2$ substrates showed highly voltage-shifted hysteresis loop compared with the films deposited on the Pt substrates. The surface of $RuO_2$ substrate was found to be reduced to metallic Ru in vacuum at elevated temperature, which caused the formation of oxygen vacancies at the initial stage of PZT film deposition and gave rise to the voltage shift in the P-E hysteresis loop of the PZT capacitor. The fatigue characteristics of the PZT capacitors under unipolar wane electric field were different from those under bipolar wane. The fatigue test under unipolar wane showed the increase of polarization. It was thought that the ferroelectric domains which had been pinned by charged defects such as oxygen vacancies and the charged defects were reduced in number by combining with the electrons injected from the electrode under unipolar wave, resulting in the relaxation of the ferroelectric domains and the increase of polarization.

• Journal of Magnetics
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• v.6 no.2
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• pp.66-69
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• 2001

The actual magnetic induction waveform of cores in electrical machines is not sinusoidal i.e. higher harmonics are always included. Thus the core loss in actual electrical machines is different from the core loss which is measured by the standard method, because the waveform of magnetic induction should be sinusoidal in the standard testing method. Core loss analysis under higher harmonic induction is always important in electric machine design. In this works we measured the core loss when a hysteresis loop has only one period of an ac minor loop of higher harmonic frequency, depending on the position of the ac minor loop of relative to the fundamental harmonic frequency. From this experiment, the core loss P(B/sub 0/f/sub 0/, B/sub h/, nf/sub 0/)) under a higher harmonic magnetic induction B/sub h/ could be expressed by the linear combination the core loss at fundamental harmonic frequency P/sub c/(B/sub 0/, f/sub 0/), the core loss of ac minor loop at zero induction region of the major hysteresis loop P/sub cL/ (B/sub h/, nf/sub 0/), and the core loss of an ac minor loop in the high induction region of the major hysteresis loop P/sub cH/ (B/sub h/, nf/sub 0/) i.e., P/sub c/, (B/sub 0/, f/sub 0/, B/sub h/, nf/sub 0/)=P/sub c/ (B/sub 0/, f/sub 0/,)+(n-1)[k₁(B/sub 0/) P/sub cL/ (B/sub h/, nf/sub 0/)+(1-k₁(B/sub 0/)) P/sub cH/ (B/sub h/, nf/sub 0/)]. This will be useful formula for electrical machine designers and one of effective methods to predict core loss including higher harmonic induction.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.10
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• pp.399-406
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• 1985

In this paper transparent PLZT ceramics for the composition of 9/65/35 (La/Zr/Ti ) are fabricated using hotpress and the possibility of application to optical shutter is examined by obtaining the On-Off characteristics of specimens. The ferroelectric E-P hysteresis loop exhibits slim loop suitable for the quadratic electrooptic effect. Measurements of the electrooptic effect show that specimens have the quadratic electrooptic effect but the light intensities as functions of electric field exhibit butterfly type hysteresis curves because of its slightly large saturation remanent polarization and coercive field. On-Off characteristics are obtained by electric fields of-6 kv/cm and +2kv/cm. As a result of experiments, 9/65/35 PLZT ceramics can be applied to optical shutter but construction with other composition which has more slim hysteresis loop is desired for obtaining the Off state by zero electric field.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1705-1707
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• 1997

In this work, a possible new PD de technique, based on the electro-optic effect(P effect), has been proposed. The refractive index ellipsoid of EO crystal, as $LiNbO_3$, is changed by both the externally a electric field and its hysteresis loop of which effect on this hysteresis loop gives rise t discrepancy of index variation. Therefore, an eq regarding the phase variation of modulated beam through $LiNbO_3$ crystal under applied e field, is newly proposed considering the influen hysteresis characteristics. For this purpose generated from needle-plane electrode in oil has detected by use of $LiNbO_3$ cell and analyzed b equation. As a result, it is observed that PD measu phase intervals are limited by the cr characteristics such as asymmertrical P-E hyst and half-wave voltage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.12
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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]

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.401-405
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• 2004

Undoped SrB $i_2$T $a_2$O$_{9}$, donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ and acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99$ ceramics were prepared and their microstructure, ferroelectric P-E hysteresis and Curie temperature were investigated. Grain size did not influence P-E hysteresis curve in undoped SrB $i_2$T $a_2$O$_{9}$ ceramics. Donor-Doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics showed more saturated P-E hysteresis curve with larger remanent polarization (P$_{r}$) than undoped SrB $i_2$T $a_2$O$_{9}$ ceramics while acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99}$ ceramics led to a pinched P-E hysteresis loop. Larger polarization in donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics resulted from easier domain wall motion by Sr-vacancies.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.2
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• pp.138-145
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• 1998

The $(Pb_{0.9}Ca_{0.1})TiO_3$[PCT] thin films have been deposited by sol-gel processing on Si-wafer and ITO glass substrates. The creak-free films have been obtained by rapid thermal annealing at $700^{\circ}C$ for 10 minute and characterized by XRD, SEM and electrical measurements. Their tetragonality c/a was 1.041 and grain size was $0.15{\sim}0.2{\mu}m$. When the electrode system of sample was Au/PCT/ITO(MFM) and film thickness was $0.8{\mu}m$, dielectric constant, dielectric loss and Curie temperature were about 149, 0.085 and $449^{\circ}C$ at 10kHz, respectively. Spontaneous polarization $P_s$, remnant polarization $P_r$ and coercive field $E_c$ were about $5.29{\mu}C/cm^2$, $4.15{\mu}C/cm^2$ and 82kV/cm calculated by hysteresis loop.

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.11a
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• pp.22.2-22.2
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• 2006

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.136-139
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• 1999

The post-annealing treatments on RF (Radio Frequency) magnetron sputtered PZI(Pb$\_$1.05/(Zr$\_$0.52/, Ti$\_$0.48/)O$_3$thin films(4000${\AA}$) have been investigated. for a structure of PZT/Pt/Ti/SiO$_2$/Si Crystallization pproperties of PZT films were strongly dependent on RTA(Rapid Thermal Annealing) annealing temperature. We were able to obtain a perovskite structure of PZT at a low temperature of 600$^{\circ}C$. P-E curves of Pd/PZT/Pt capacitor annealed at 700$^{\circ}C$ demonstrate typical hysteresis loops. The measured values of P$\_$r/, E$\_$c/, by post annealed at 700$^{\circ}C$ were 12.1 ${\mu}$C/$\textrm{cm}^2$, 120KV/cm respectively.

• Transactions on Electrical and Electronic Materials
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• v.1 no.1
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• pp.17-21
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• 2000

In order to investigate the dependence of a content in lead lanthanum titanate (PLT) films and heat treatment, sol-gel process has been used. Four types of PLT thin films with the chemical formula, Pb$\_$1-x/ La$\_$x/Ti$\_$1-x/4/O$_3$(X=18, 21, 24 and 28 mole %) have been fabricated on Pt/Ti/SiO$_2$/Si multi-layers and ITO/glass substrates, The post-annealing temperature in the range of 400~700 $\^{C}$ is applied for the formation of perovskite structure in PLT films. The structureal, electrical and optical properties of PLT film with the addition of La content are estimated. The films orientation and surface structure of films are studied by XRD (X-ray diffraction) and SEM(scanning electron microscopy). The P-E hysteresis loop become narrower with increasing La content. The average transmittance of the films is about 80%.