• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.697-700
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• 2001

In this paper, the structural and electrical properties of the Sr$_{1-x}$ Ca$_{x}$TiO$_3$ (0$\leq$x$\leq$0.2) (0$\leq$r$\leq$0.2)-based grain boundary layer ceramics were investigated by X-ray, SEM and V-I system. Increasing the Ca content, the average grain size and the lattice constant were decreased. The relative density of all specimens was >96%. The 2nd phase formed by thermal diffusing from the surface lead to a very excellent electrical properties, that is, $\varepsilon$$_{r}$>50000, tan$\delta$<0.05, $\Delta$C< $\pm$ 10%.\pm$ 10%.%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.72-75
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• 2001

In this paper, the $Sr_{1-x}Ca_{x}TiO_{3}(0{\leq}x{\leq}0.2)$ 2)-based grain boundary layer ceramics were fabricated to measured dielectric properties and voltage-current properties. The sintering temperature and time were $1420\sim1520^{\circ}C$, 4hours, in $N_{2}$ gas, respectively. The structural and the dielectric properties were investigated by SEM, X-ray, HP4194A and K6517. The 2nd phase formed by thermal diffusion from the surface lead to a very high apparent dielectric constant, $\varepsilon_r$ > 50000. X-ray diffraction patterns exhibited cubic structure for all specimens. Increasing content of Ca, the peak intensity were decreased.ﱇﶖ⨀ਆᘍ܀㘱㔮㠹㬅K䍄乍

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.2
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• pp.111-120
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• 1998

In this paper, the $(SrPb)(CaMg)TiO_3$ ceramics with paraelectric properties were fabricated by the mixed oxide method. It was investigated that which the variation of contents of $Bi_2O_3{\cdot}3TiO_2$ effects on structural, dielectrical and electrical properties of specimens. As a result, the grain size were grown with increasing the contents of $Bi_2O_3{\cdot}3TiO_2$. The relative dielectric constants were increased up to 4[mol%] of $Bi_2O_3{\cdot}3TiO_2$, and decreased more or less at a low temperature in the specimens which had more than. But the temperature coefficient. of capacitance were showed ${\pm}25$[%]. The dielectric loss were less than 0.05 in all specimens which had more than 4[mol%] of $Bi_2O_3{\cdot}3TiO_2$. In order to investigate the behavior of charged particles, the characteristics of electrical conduction were measured. As a result, the conduction current was divided into the three steps as a function of DC electric field. The first step was Ohmic region due to ionic conduction, below 15[kV/cm]. The second step was showed a saturation which seems to be related to a depolarizing field occuring in field-enforced ferroelectric phase, between 15[kV/cm] and 40[kV/cm]. The third step was attributed to Child's law related to space charge which injected from electrode, above 40[kV/cm].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.34-37
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• 2001

In this study, the capacitance-voltage properties of (Sr$_{1-x}$ .Ca$_{x}$)TiO$_3$(0.05$\leq$x$\leq$0.20)-based grain boundary layer ceramics were investigated. The ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were 1480~150$0^{\circ}C$ and 4 hours, respectively. The 2nd phase formed by the thermal diffusion of CuO from the surface leads to very excellent dielectric properties, that is, $\varepsilon$$_{r}$>50000, tan$\delta$<0.05, $\Delta$C<$\pm$10%. The capacitance is almost unchanged below about 20[V] but it decreases slowly about 20[V]. The results of the capacitance-voltage properties indicated that the grain boundary was composed of the continuous insulating layers.ulating layers.s.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.188.2-188.2
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• 2015

The presence of the conduction interface in epitaxial $LaAlO_3/SrTiO_3$ thin films has opened up challenging applications which can be expanded to next-generation nano-electronics. The metallic conduction path is associated with two adjacent insulating materials. Such device structure is applicable to frequency-dependent impedance spectroscopy. Impedance spectroscopy allows for simultaneous measurement of resistivity and dielectric constants, systematic identification of the underlying electrical origins, and the estimation of the electrical homogeneity in the corresponding electrical origins. Such unique capability is combined with the intentional control on the interface composition composed of $SrTiO_3$ and $CaTiO_3$, which can be denoted by $SrxCa1-_xTiO_3$. The underlying $Sr_xCa1-_xTiO_3$ interface was deposited using pulsed-laser deposition, followed by the epitaxial $LaAlO_3$ thin films. The platinum electrodes were constructed using metal shadow masks, in order to accommodate 2-point electrode configuration. Impedance spectroscopy was performed as the function of the relative ratio of Sr to Ca. The respective impedance spectra were analyzed in terms of the equivalent circuit models. Furthermore, the impedance spectra were monitored as a function of temperature. The ac-based characterization in the 2-dimensional conduction path supplements the dc-based electrical analysis. The artificial manipulation of the interface composition will be discussed towards the electrical application of 2-dimensional materials to the semiconductor devices in replacement for the current Si-based devices.

• Proceedings of the Korea Crystallographic Association Conference
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• 2003.05a
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• pp.19-19
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• 2003

A cubic perovskite-type CaCu₃Ti₄O/sub 12/ compound has recently drawn a great attention because of an extraordinary high permittivity (～10⁴ at 1 kHz) at room temperature and its near temperature-independence over a wide temperature region, and thus numerous literature have been reported on CCTO polycrytalline ceramics and thin films. However, only a few literature have been reported on the CCTO single due to the lack of information about the CCTO primary phase field. On the basis of our recent experimental determination of the CCTO primary phase field, we could grow ACu₃Ti₄O/sub 12/(A=Ca, Sr) single crystals using both top-seeded solution growth and flux growth methods. This presentation will include three major parts. In part I, the thermal decomposition reaction of CCTO and its primary phase field in the CaO-CuO-TiO₂ ternary system will be presented. Detailed growth conditions of ACu₃Ti₄O/sub 12/(A=Ca, Sr) single crystals and characteristics of as-grown crystals will be followed in Part II. Part III will be comprised of dielectric properties of as-grown ACu₃Ti₄O/sub 12/(A=Ca, Sr) single crystals. Our experimental results will be compared with those of previous reports for discussion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.196-197
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• 2006

In this study, low temperature sintering multilayer piezoelectric transformer for DC-DC converter were manufactured using (PbCaSr)Ti(MnSb)$O_3$ ceramics and thin their electrical properties were investigated according to the vanation of frequency and load resistance. The voltage step-up ratio of multilayer piezoelectric transformer showed the maximum value m the vicinity of 1.3MHz and increased according to the increase of load resistance. When the output impedance coincided with the load resistance, the piezoelectric transformer showed the temperature rise of about $21^{\circ}C$ under the output power of 6W.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.879-884
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• 2001

In this paper, the structural and dielectric properties of (Sr$_{l-x}$Ca$_{x}$)TiO$_3$ (0$\leq$x$\leq$0.2) -based grain boundary layer ceramics were investigated by XRD, SEM and HP4194A. The ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were 1420~152$0^{\circ}C$ and 4 hours, respectively. The average grain size and the lattice constant were decreased with increasing content of Ca. The average grain size was increased with increase of sintering temperature. The relative density of all specimens was 96~98%. The 2nd Phase formed by the thermal diffusion of CuO from the surface leads to very excellent dielectric properties, that is, $\varepsilon$$_{r}$>50000, tan $\delta$<0.05, $\Delta$C<$\pm$10%. The appropriate Ca content was under 15 ㏖%.s under 15 ㏖%.%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.79-82
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• 2002

$(Ba_{0.6-x}Sr_{0.4}Ca_x)TiO_3$ + ywt% MgO (x=0.10, 0.15, 0.20, y=0.0~3.0) ceramics were fabricated by the conventional solid-state reaction, and their structural and dielectric properties were investigated with variation of composition ratio and MgO doping content. A second phase, representative of MgO, appears in 3wt% MgO-doped BSCT specimens. Average grain sizes decreased with increasing amounts of MgO, and the BSCT(40/40/20) specimens doped with 3wt% MgO showed a value of $9.3{\mu}m$. The Curie temperature and relative dielectric constant at room temperature were decreased with increasing MgO doping content and Ca composition ratio. The relative dielectric constant was non-linearly decreased as the field strength is increased. The tunability was increased with decreasing a Ca content and the BSCT(50/40/10) specimen doped with 1.0wt% MgO content showed the highest value of 6.4% at 5kV/cm.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1493-1495
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• 2001

$(Ba_{0.6-x}Sr_{0.4}Ca_x)TiO_3+yAl_2O_3$ wt% (x=0.10, 0.15, 0.20, y=0.5 $\sim$ 3.0) specimens were fabricated by the mixed-oxide method and then the structural properties as a function of the composition ratio and $Al_2O_3$ contents were studied. All BSCT specimens showed dense and homogeneous structure without the presence of the seconds phase. The sintered density was decreased with increase ad $Al_2O_3$ content. The Curie temperature and dielectric constant at room temperature decreased with increasing $Al_2O_3$ content. The dielectric constant and dielectric loss of the doped-0.5 wt% $Al_2O_3$ BSCT(50/40/10) specimen were about 3131 and 0.932% at 1KHz, respectively.