• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.7
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• pp.546-551
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• 1998

$Mn{1-X}Fe{2+X}O_4, Mg_{1-X}Fe_{2+X}O_4$ (x=0.0, 0.025, 0.1, 0.2) for negative temperature coefficient (NTC) thermistor was prepared by calcination at $800^{\circ}C$ and sintering at form 1100 to $1250^{\circ}C$ with $50^{\circ}C$ intervals. The best linear property was obtained in the Mn-based sample sintered at $1200^{\circ}C$ with x=0.0 composition. Temperature coefficient of resistance, $\alpha$, was $-5.6%/^{\circ}C$ in the Mn-based sample, $-5.2%/^{\circ}C$ in the MM-based sample, and $-1.6%/^{\circ}C$ in the Mg-based sample. thermistor parameter, B, was in the range of 2665~7780 K. The results show the possibility that Mn-Ni-Co based thermistor could be substituted by the composition used in this study.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.5
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• pp.218-227
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• 2021

A thick film NTC thermistor for low temperature co-firing was manufactured by printing and sintering a paste prepared using NTC powder of Mn_1.5Ni_0.4Co_0.9Cu_0.4O₄ composition, lead free frit, and RuO₂ on a 96 % alumina substrate. The effect of frit and RuO₂ on the electrical properties of thick film NTC thermistor was studied. The resistance of the thick film NTC thermistor was higher than that of the bulk phase sintered at the same temperature, but it was found that the negative resistance temperature characteristic appeared more clearly and linearly in the resistance - temperature characteristic. On the other hand, the area resistance decreased as the sintering temperature increased, and the area resistance increased as the amount of frit added increased. The B constant of the thick film NTC thermistor was 3000 K or higher. Among them, it was found that the B constant of the thick film NTC thermistor made of paste with 5 wt% of frit added and sintered at 900℃ showed the highest B constant. Also, it can be seen that the area resistance decreased with the addition of RuO₂, and the change in the area resistance decrease of the thick film NTC thermistor obtained by sintering the paste containing 5 wt% of RuO₂ at 900℃ is the most obvious.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.88-92
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• 2003

The correlationship between heat treatment condition and electrical properties of the Mn-Co-Ni oxide NTC thermistor for fuel level sensor was investigated by the X-ray diffractometry, density measurement, and electrical properties measurement such as resistivity, B constant, and thermal dissipation constant. It was shown that the heat treatment of NTC thermistor was responsible for sinterability of Mn-Co-Ni oxide. The highest density of 5.10 g/㎤ was obtained at $1250^{\circ}C$, 2 hours, at which the densification was almost completed. This is also manifested from the microstructural observation. It is found that the electrical resistivity and B constant are increased at the elevated sintering temperatures. The NTC specimens prepared in this study showed the conventional decrease of resistance with the measured temperature and the linear behavior of output voltage with fuel levels. Therefore, the electrical properties of thermistor were closely correlated with sintering condition. and the Mn-Co-Ni oxide thermistor prepared in this study has a great possibility enough to apply for an automobile fuel level sensor.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.1
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• pp.28-37
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• 2018

In order to study the NTC thermistor that can be fired at low temperature, the influence of the lead free glass frit and $RuO_2$ addition on the electrical properties of the NTC thermistor of $Mn_{1.85}Ni_{0.25}Co_{0.9}O_4$ basic composition was studied. The sintering characteristics of the specimen sintered at $1000^{\circ}C$ with 10 wt% frit added to the basic NTC composition were similar to those of the specimen sintered at $1200^{\circ}C$ without frit. However, as the amount of frit increased, the electrical resistivity and B constant were increased. In order to reduce the resistance, NTC thermistor was prepared by adding 0, 2, and 5 wt% of $RuO_2$ to the composition containing 10 wt% of frit and sintered at $1000{\sim}1200^{\circ}C$, and sintering and electrical properties were measured. The electrical resistivity and the B constant tended to decrease with increasing $RuO_2$ content. However, the resistivity was the lowest at sintering temperature of $1000^{\circ}C$ and the resistance increased with increasing sintering temperature after 5 wt% $RuO_2$ addition. The NTC thermistor sintered at $1000^{\circ}C$ with 10 wt% frit and 5 wt% $RuO_2$ in the composition of NTC showed similar electrical properties and sintering characteristics when sintered at $1200^{\circ}C$ without added frit.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.93-96
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• 1989

NTC thermistor was prepared by adding TiO$_2$and MnO$_2$on Fe$_2$O$_3$and the effects of additions were investigated. And the effects of compating pressure, sintering temperature, and sintering time were also experimented. Fe$_2$O$_3$is insulator in stoichiometric state and will be semiconductor by introducing Ti$^{+4}$, Sn$^{+4}$. These semiconducting material will show large negative temperature coeffecients and can be used as NTC thermistor.tor.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1674-1676
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• 1999

Oxide of the form $Mn_3O_4-CuO-Co_3O_4$-NiO-ZnO present properties that make them useful as power NTC thermistor for current limited. Power NTC thermistor electric properties of $Mn_3O_4-CuO-Co_3O_4$-NiO-ZnO system has been measured as a function of temperature and composition and current - voltage, time constant, activation energy, heat dissipation coefficient have also been determined.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.506-508
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• 2000

Oxide of the form $Mn_{3}O_{4}-NiO-Fe_{2}O_{3}$ present properties that make them useful as multilayer chip NTC thermistor for mobile phone NTC thermistor electric properties of $Mn_{3}O_{4}-NiO-Fe_{2}O_{3}$ system has been measured as a function of temperature and composition. In $Mn_{3}O_{4}-NiO-Fe_{2}O_{3}$ composition, it can be seen that resistivity and B-constant were increased as the ratio of $Mn_{3}O_{4}/F_{2}O_{3}$ and $Mn_{3}O_{4}$/NiO was increased. In particular, resistance change ratio (${\Delta}R$), the important factor for reliability varied within ${\pm}1%$, indicating the compositions of these products could be available for mobile phone.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.97-100
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• 1989

Thermistor is the semiconducting material whose electrical resistance is varied with its self heating. In this paper, the improvement of resistance-temperature characteristics of NTC thermistor devices based on NiO was experimented. The specimens were prepared by mixing NiO and Mn$_2$O$_3$(1:1 mole %) and by addition of CuO(1 wt %, 2 wt %, 4 wt %). The specimens were compacted at the pressure of 1000 kg/$\textrm{cm}^2$ and sintered for 1 hour in air ambient at 120$0^{\circ}C$. Reducing CuO additions not only resistance-temperature characteristics, but also increased room temperature resistance.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.181.2-181
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• 2003

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.459-462
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• 2001

Interface effects on properties of NTC thermistors having Mn-Co-O spinel crystal structure system are analyzed by a mixing rule in case of mixed types and layered types between CuO and Al$_2$O$_3$ added compounds. With adding CuO and Al$_2$O$_3$, The compounds form completely solid solution and their resistance and B constant are changed due to the variation of conduction electrons by their ionic substitutions. The properties of mixed NTC thermistors are depended on the logarithmic mixing rule by a dispersed phase and they show slightly lower values due to the lattice mixing affect in compared with calculated values. The resistance of layered NTC thermistors is depended upon the series mixing rule containing the value of an interface layer and effected by the variation of its thickness, and it is changed rapidly to the logarithmic mixing rule by the connection between two layers with increasing the interface layer