• 항공우주시스템공학회지
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• 제13권2호
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• pp.43-50
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• 2019

위성 및 항공기 부속품 등은 온도 영향에 따라 미션의 가능성 및 안전에 큰 영향을 받게 된다. 또한 무인기를 위해 연구가 활발히 진행되고 있는 연료전지 분야에서도 효율성 및 안정성을 위해 온도는 필수적으로 확인되어야 한다. 본 논문은 큐리 온도 이상에서 저항이 급격히 변화하는 PTC 서미스터의 특성을 이용하기 위해 $BaTiO_3$와 세라믹 성분을 변화시킨 $SrTiO_3$를 이용하여 스마트 페인트를 제작하였으며, 박리를 방지하기 위하여 코팅제를 제작해 코팅 후 저항 변화를 확인하였다. 또한 코팅 전후 $BaTiO_3$ 와 $SrTiO_3$의 온도 변화에 따른 저항 변화를 측정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.15-15
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• 2010

$Na_2Ti_6O_{13}$ (NT)가 도핑된 $BaTiO_3-(Bi_{0.5}Na_{0.5})TiO_3$ BBNT) PTCR 세라믹스를 변형된 세라믹공정을 이용하여 제조하였다. 제조된 BBNT 세라믹의 미세구조와 PTCR 특성에 미치는 NT의 효과를 조사하였다. $1300^{\circ}C$에서 합성된 BBNT 세라믹은 NT의 도핑량이 증가함에 따라 비정상적으로 성장된 입자의 수가 증가하였다. 뿐만 아니라, NT의 도핑량 증가는 상온비저항을 약간 증가시켰지만 큐리온도 (Tc) 부근의 최대비저항/최소비저항으로 정의되는 PTC 점프 특성을 크게 향상시켰다. 특히, 0.01mol%의 NT 도핑 시 상온비저항은 $425\;\Omega{\cdot}cm$, PTC 점프는 ($2.02{\times}^10^5$) 저항온도계수는 69.8% 및 Tc는 $155^{\circ}C$의 우수한 결과를 나타내었다.

• 한국세라믹학회지
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• 제32권1호
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• pp.140-144
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• 1995

The role of Mn on the PTCR characteristics of La-doped BaTiO3 ceramics was studied. The calculated Ns value was increased with Mn concentration and consequently pmax and pmin were increased. The behavior of pmin was explained by the Jonker's theory, and Ns value of 6.35×1017m-2 was well agreed with the theoretical estimate of Jonker's. The value state of Mn was measured by ESR, and changed around Tc from ＋3 in tetragonal phase to ＋2 in cubic phase. Therefore, the amount of electron trap increased at Tc led to the great improvement of PTC R characteristics.

• 한국세라믹학회지
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• 제26권1호
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• pp.7-12
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• 1989

The effects of composition ratios and sintering conditions in Co1-xMgxO ceramics on the sintering characteristics, electrical properties and oxygen sensing characteristics were investigated. In the same sintering conditions, porosity decreased with increase of MgO contents. The relationshiop of temperature and resistance in Co1-xMgxO ceramics showed NTC(negative temperature coefficient) characteristics at the temperature range from $700^{\circ}C$ to 1,10$0^{\circ}C$. In the case of pure CoO, however, the PTC(positive temperature coefficient) characteristics were shown over about 90$0^{\circ}C$. The electrical conductivity of Co1-xMgxO ceramics decreased proportionally with decrease of oxygen partial pressure at the range from 1 to 10-4(atm). Particularly, Co0.5Mg0.5O ceramics showed the highest sensitivity to oxygen gas.

• 한국세라믹학회지
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• 제25권1호
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• pp.42-48
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• 1988

Commercially available PTCR (Postive Temperature Coefficient of Resistivity) ceramics which have low room temperature resistance, high PTC effect and temperature coefficient were prepared by La3+ doped semiconducting barium calcium titanate soild solutions. PTCR characteristics were remarkably improved by addition of AST (1/3 Al2O3$.$3/4SiO2$.$1/4TiO2) and MnCl2. That can be explained by formation of liquid phase during sintering and acceptor level on the intergranular layer. Resistivity anormaly increased with decreasing cooling rate. Optimum manufacturing conditions were cooling rate below 100$.$C/hr, Ca and Mn content of 4 mol% &, 0.09-0.12mol% respectively.

• E2M - 전기 전자와 첨단 소재
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• 제8권1호
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• pp.77-82
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• 1995

PTCR(Positive Temperature Coefficient of Resistivity) thermistor in thin film BaTiO$_{3}$ system was prepared by using radio frequency(13.56 MHz) and DC magnetron sputter equipment. Polycrystalline, surface structure, and R-T(Resistivity-Temperature) characteristics of the specimens were measured by X-ray diffraction(D-Max3, Rigaku, Japan), SEM(Scanning Electron Microscopy: M.JSM84 01, Japan), and insulation resistance measuring system (Keithley 719), respectively. Thin films characteristics of the thermistor showed different properties depending on the substrate even with the same sputtering condition. The thin film formed on the A1$_{2}$O$_{3}$ substrate showed a good crystalline and a low resistivity at below curie point. However, the thin films prepared on slide glass and Si wafer were amorphous. The thicknesses of the three samples prepared under the same process conditions were 700[.angs.], 637.75[.angs.], and 715[.angs.], respectively.

• 한국세라믹학회지
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• 제37권10호
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• pp.968-974
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• 2000

Nb$_2$O$_{5}$와 MnO 첨가에 따른 Pb$_{0.6}$Sr$_{0.4}$TiO$_3$반도체 세라믹의 미세구조와 전기적 특성은 유전특성, I(current)-V(voltage) 측정, 그리고 복소 임피던스 측정 등을 이용하여 고찰하였다. Nb 도핑량이 0.4 mol% 이하인 경우 Nb 도핑량에 따라 전도성과 입성장은 증가되었으나 그 이상의 도핑량에서는 Sr이나 Pb 공공의 생성으로 인하여 전도성이 감소되고 입성장도 억제되는 것을 관찰할 수 있었다. 0.4 mol% Nb-doped Pb$_{0.6}$Sr$_{0.4}$TiO$_3$에 0.01 mol% MnO를 첨가한 경우 비저항비($ ho$$_{max}$/$\rho$/min/)가 $10^2$에서 $10^4$으로 크게 향상되었다. 그리고 전이 온도 주변에서 여러 개의 변곡점을 지니는 비옴성 거동이 발견되었다. 이와 같은 현상은 입계에 존재하는 Mn 이온이 부분적으로 편석되어 표면 전하의 보상 효과에 영향을 미치는 것이라고 사료된다.

• The Korean Journal of Ceramics
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• 제2권4호
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• pp.238-241
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• 1996

New porous BaTiO$_3$ thermistors were fabricated using graphite powders (0 to 10 wt. %) and their porosities were in the range of 9.1% to 16.2%. As results of impedance analysis, it was confirmed that the pores affected the grain-boundary resistance and the bulk (grain interior) resistance was constant as about 25 $\Omega$ at room temperature. The magnitude of PTCR effect $(p_{max}/p)$ markedly increased from 3 orders to 7 orders without addition of any acceptor dopant such as Mn or Cr.

• 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 $T_c=141^{\circ}C$.

• 한국전기전자재료학회논문지
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• 제21권7호
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• pp.638-644
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• 2008

The effects of $Nb_2O_5$ and $MnO_2$ on the positive temperature coefficient of resistivity (PTCR) behavior of lead-free $Ba_{0.99}(Bi_{1/2}Na_{1/2})_{0.01}TiO_3$ (BaBiNT) ceramics were investigated in order to fabricate a PTC thermistor available at high temperature of > $120^{\circ}C$. In particular, 0.05 mol% $Nb_2O_5$ added BaBiNT ceramic, which has significantly increased Curie temperature (Tc) of $160^{\circ}C$, showed good PTCR behavior; low resistivity at room temperature $(\rho_r)$ of $80.1{\Omega}{\cdot}cm$, a high $\rho_{max}/\rho_{min}$ ratio of $5.65{\times}10^3$ and a large resistivity temperature factor (a) of 18.5%/$^{\circ}C$. Furthermore, the improved $\rho_{max}/\rho_{min}$ of $6.48{\times}10^4$ and a of 25.4%/$^{\circ}C$ along with higher $T_c$ of $167^{\circ}C$ despite slightly increased $\rho_r$ of $569{\Omega}{\cdot}cm$, could be obtained for the BaBiNT + 0.05 mol% $Nb_2O_5$ + 0.02 wt% $MnO_2$ ceramic cooled down at a rate of $200^{\circ}C/h$.