• 한국세라믹학회지
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• 제18권2호
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• pp.119-125
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• 1981

The thermostable resistor was made by using P.T.C.R-N.T.C.R. ceramics. In this study $BaTiO_3$ type P.T.C.R. ceramics and $SnO_2-Sb_2O_3$ type N.T.C.R. ceramics were cocrystallized in one body and electrical resistance was stable under the temperature variation between $25^{\circ}C$-40$0^{\circ}C$. The ceramics showed the most stable electrical resistance for the mal variation when the composition was 0.6P.T.C.R. $BaTiO_3$,$ 0.4SnO_2$ and 0.01 $Sb_2O_3$.

• 한국전기전자재료학회논문지
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• 제30권4호
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• pp.223-228
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• 2017

In this study, in order to develop composition ceramics for refrigeration device application at a temperature of less than $90^{\circ}C$, a $Ba(Ti_{1-x}Zr_x)O_3$ composition was fabricated using a conventional solid-state method. Electrocaloric properties of these ceramics were investigated using the characteristics of P-E hysteresis loops in a wide temperature range from room temperature to $150^{\circ}C$. The Curie temperature of $Ba(Ti_{1-x}Zr_x)O_3$ ceramics decreased with the increase of x. The maximum value of ${\Delta}T=0.07^{\circ}C$ in an ambient temperature of $85^{\circ}C$ under 30 kV/cm appeared when x = 0.125. It was concluded that the composition (x = 0.125) ceramics can be used for refrigeration device applications.

• 한국세라믹학회지
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• 제30권5호
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• pp.397-403
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• 1993

Widely used dielectrics, barium titanate was promising material for ceramic capacitor. It was produced by specific formulation with various dopants-La2O3, ZrO2, SnO2, CaZrO3, CaTiO3, CaSnO3, Bi2O3, and etc.-according to demanded properties of capacitor. In this study, we would examinate the study of dielectric properties and temperatuer characteristics (T.C.) with the amount of Bi2O3. The sample was prepared with [BaTiO3]10＋[BaZrO3, SnO2, La2O3, ZrO2]10 and Bi2O3 varied from 1.0, 1.5, 2.0, 2.5 to 3.0wt%. After milling and mixing for 15hrs, each sample was dried and then pressed at 700kg/$\textrm{cm}^2$ into pellets. Pellets were fired at 131$0^{\circ}C$, for 3hrs in air. As the result of measurements, dielectric constant, break down voltage, and insulation resistance were increased with the amount of Bi2O3, and the resonant frequency was shifted from high frequency to low frequency range. In the case of temperature characteristics, capacitance change rate was symmetrically changed at -$25^{\circ}C$ and ＋85$^{\circ}C$ respectively. Therefore, it is recognized that the temperature characteristics can be moderated with doping Bi2O3 in our study.

• 대한전기학회논문지
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• 제43권3호
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• pp.442-446
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• 1994

In this study, microwave dielectric properties of 0.182BaO-0.818TiOS12T ceramics were investigated with sintering temperature and annealing time, and the application for the microwave dielectric resonator was studied. In the specimen simtered at 1400[$^{\circ}C$], dielectric constant, unloaded Q and temperature coefficient of resonant frequency had good values of 35.36, 5692, -4.43[ppm/$^{\circ}C$], respectively. The specimen which temperature coefficient of resonant frequency($\tau$f) was vared positive to negative value was selected, thereafter microwave dielctric properties was investigated with annealing time(0~4[hr]) in the fixed annealing temperature of 1350[$^{\circ}C$]. Increasing the annealing time, dielectric constant and unloaded Q were increased and temperature coefficient of resonant frequency was decreased.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.336-336
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• 2008

A positive temperature coefficient of electrical resistivity (PTCR) was investigated in a ferroelectric lead-free perovskite-type compound $(Bi_{0.5}K_{0.5})TiO_3$ within $BaTiO_3$-based solid solution ceramics. The electrical properties and the microstructure of (1-x) $BaTiO_3$ - x $(Bi_{0.5}K_{0.5})TiO_3$ (BBKT) ceramics made using a conventional mixed and have been synthesized by an ordinary sintering technique. The Curie temperature was obviously increased with increasing of $(Bi_{0.5}K_{0.5})TiO_3$ content. The BKT ceramics (x=0.05) sintered at $1400^{\circ}C$ for 4h display low resistivity values of $10^1-10^2$ ohm cm at room temperature, PTCR effect(jump) of 1.05*$10^3$, and the Curie temperature of $T_c=141^{\circ}C$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.61-63
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• 2004

PTC Thermistors specimens were fabricated by added $MnO_2$ as donors, and $Nb_2O_5$ as acceptors and sintered $1250^{\circ}C$/2hrs. Average grain size decreased with increased in added $MnO_2$, and increased with added in $Nb_2O_5$. But, appeared liquid phase as $Bi_2O_3$ and $TiO_2$, affect to grain growth. XRD result, peak strength was lowed then crystallization not well, but, secondary phase were not showed all specimens. All specimens resistance were so high, about $40M{\Omega}$ over, couldn't measured to those resistance and doesn't appear PTCR effect.

• 한국재료학회지
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• 제9권10호
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• pp.956-961
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• 1999

초미립 $BaTiO_3$분말을 출발물질로 하고 $\textrm{La}_{3+}$을 0~2 mol% 첨가하여 $1200~1400^{\circ}C$에서 소결하였을 때 $\textrm{La}_{3+}$을 첨가하지 않고 $1350^{\circ}C$ 이상에서 소결한 경우를 제외하고는 모두 110~240 nm의 평균입경을 갖는 초미립의 $\textrm{La}_{3+}$-doped $BaTiO_3$소결체를 얻을 수 있었다. 이 때, 평균입경이 240 nm에서 110 nm로 감소함에 따라 정방정비 (c/a), $90^{\circ}$ 분역의 부피분율, 상온 비유전율, 상전이온도($\textrm{T}_{c}$)에서의 최대 비유전율, $\textrm{T}_{c}$ 에서의 상전이 완만화도 등은 모두 감소하였다. 이와 같은 유전특성의 입경 의존성은 평균입경 감소에 따른 $90^{\circ}$ 분역 생성의 억제 및 그에 따른 내부응력의 영향으로 해석하였다.

• 한국재료학회지
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• 제4권1호
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• pp.3-8
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• 1994

최근 중요하게 된 진동 흡수를 위해서 $BaTiO_{3}$ 세라믹의 흡진 특성을 측정하고 미세구조와의 연관을 조사했다.$BaTiO_{3}$ 세라믹은 비교적 물리적 화학적으로 안정하여 좋은 흡진재로 기대된다.BaTiO$_{3}$ 세라믹은 흡진 특성을 강화시키기 위해서 섬유상 분말을 소결하여 만들었다. KDC법으로 직경이 0.2$\mu\textrm{m}$, 1.2$\mu\textrm{m}$, 2.0$\mu\textrm{m}$인 각각 다른 섬유상 $K_2Ti_4O_9$을 만들고 이온교환해서 섬유상 $BaTiO_{3}$ 을 만들었다. 면상으로 배향시킨 소결체의 흡진 특성과 전기적 물성을 조사하여 미세구조와 의 관계를 밝혔다. 소결체의 입경과 등가회로, 전기기계합계수($K_{t}$), 발생 전압(V)을 조사한 결과, 사용한 섬유의 직경이 클수록 소결체의 입경은 작아졌다. 따라서 입계가 많아졌다. 흡진 특성은 입계가 많을수록 커진다. 즉 입계의 내무마찰이 클수록 흡진률은 커지며 이때의 내부마찰은 등가회로를 조사함으로써 확인되었다.

• 한국세라믹학회지
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• 제51권6호
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• pp.623-628
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• 2014

Orthorhombic $Ba(Ti_{0.94}Zr_{0.06})O_3$ single crystals are fabricated using the cost-effective solid-state single crystal growth (SSCG) method; their dielectric and piezoelectric properties are also characterized. Measurements show that (001) $Ba(Ti_{0.94}Zr_{0.06})O_3$ single crystals have an electromechanical coupling factor ($k_{33}$) higher than 0.83, piezoelectric charge constant ($d_{33}$) of about 400 [pC/N], and piezoelectric voltage constant ($g_{33}$) higher than 50 [${\times}10^{-3}Vm/N$]. The transition temperature ($T_{OT}$) of the (001) $Ba(Ti_{0.94}Zr_{0.06})O_3$ single crystals between orthorhombic and tetragonal phases is also observed to be about $61^{\circ}C$. Because their electromechanical coupling factor ($k_{33}$) and piezoelectric voltage constant ($g_{33}$) are higher than those of soft PZT ceramics, it is expected that (001) $Ba(Ti_{0.94}Zr_{0.06})O_3$ single crystals can be used as "lead-free" piezoelectric materials in many piezoelectric applications.

• 대한화학회지
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• 제39권10호
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• pp.806-811
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• 1995

정온도저항계수(PTCR) 특성을 지닌 $(Ba,Sr)_{1-x}Y_xTiO_3$(x = 0.001-0.009, BSYT)를 옥살산공침범으로 합성하여 이트륨 혼입량 변화에 따른 전기적 특성을 관찰하였다. 온도변화에 따른 저항을 측정한 결과 이트륨의 농도가 0.3mol%로 증가할때까지는 큰 PTCR 효과를 나타낸 반면 농도가 0.5mol% 이상에서는 적은 PTCR 효과를 나타내었다. 상전이 온도($T_c$) 이상에서 온도와 $1{\varepsilon}$m(T)의 관계를 나타낸 도시에 의하면 유전상수의 변화가 Curie-Wiess 법칙에 잘 따름을 알 수 있었다. 측정한 비저항과 유전상수로부터 계산한 전위장벽위 높이를 온도에 따라 도시한 결과 PTCR 효과와 마찬가지로 이트륨의 혼입량이 0.3mol%로 증가할때까지는 높은 전위장벽이 유지되나 0.5mol% 이상에서는 비교적 낮은 전위장벽을 나타내었다.