Compositions – Electrically conductive or emissive compositions – Metal compound containing
Reexamination Certificate
2006-06-06
2006-06-06
Kopec, Mark (Department: 1751)
Compositions
Electrically conductive or emissive compositions
Metal compound containing
C252S521100, C252S521200, C252S519510, C252S520500, C338S0220SD, C338S0220SD, C501S127000
Reexamination Certificate
active
07056453
ABSTRACT:
The thermistor portion of a thermistor device consists of a mixed sintered body of aY(Cr0.5Mn0.5)O3.bAl2O3made of the perovskite-type compound Y(Cr0.5Mn0.5)O3and Al2O3, or a mixed sintered body of aY(Cr0.5Mn0.5)O3.b(Al2O3+Y2O3) made of Y(Cr0.5Mn0.5)O3, Al2O3and Y2O3. The mole fractions a and b have the relationships 0.05≦a<1.0, 0<b≦0.95 and a+b=1. This is required to obtain a thermistor device that has stable characteristics and exhibits a small change in its resistance value, even in a heat history from room temperature to 1000° C. or the like, and also has a resistance value of 50Ω to 100 kΩ in the temperature range from room temperature to 1000° C.The precursor compounds triethoxy yttrium, diethoxy manganese and tris (2,4-pentadiono) chromium are mixed in a mixed solvent of ethanol and isopropyl alcohol, and refluxing is performed to obtain a composite metal alkoxide solution. Then the metal salt precipitating agent of deionized water is added, the mixture is stirred and mixed and refluxing is performed to obtain a gelatinous precipitate of metallic salts containing Y, Mn and Cr. This precipitate is separated by filtration, dried and calcined to obtain powdered raw material with a composition of 38Y(Cr0.5Mn0.5)O3.62Y2O3, the same as that of a thermistor device. Thereafter, this powdered raw material is molded and sintered to obtain the thermistor device as a sintered body. Thereby, the dispersion of the resistance value of the thermistor can be reduced.An anti-reducing coating made of an anti-reducing material such as Y2O3, Al2O3, Y3Al5O12, 3Al2O3.SiO3, Y2SiO5or the like is formed on the surface of a thermistor portion consisting of a mixed sintered body of Y(CrMn)O3.Y2O3(or Y(CrMn)O3.Al2O3) or the like to form a thermistor device with a pair of lead wires attached. Thereby, the thermistor device exhibits resistance value stability even when subjected to a reducing atmosphere.
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Periodic Table f the Elements, no date.
Kuzuoka Kaoru
Ogata Itsuhei
Yasuda Eturo
Denso Corporation
Kopec Mark
Nippon Soken Inc.
Nixon & Vanderhye PC
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