# US 8,771,559 B2 · Conductive sintered oxide, thermistor element including the same, and temperature sensor including the same

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- Number: US 8,771,559 B2
- Document ID: US8771559B2
- Status: Granted
- Kind: B2
- Application number: 13/210,684
- Filed: 2011-08-16
- Published: 2012-02-23
- Granted: 2014-07-08
- Earliest claimed: 2010-08-17
- Assignees: Ngk Spark Plug Co., Ltd.
- Applicants: Hiroshi Watanabe; Yasuyuki Okimura; Shinji Ban; Takeshi Mitsuoka
- Inventors: Hiroshi Watanabe; Yasuyuki Okimura; Shinji Ban; Takeshi Mitsuoka
- Web page: https://patentgrep.com/patent/US8771559B2

## CPC

- H01C 7/008: {Thermistors (H01C7/02 - H01C7/06 take precedence)}
- C04B 35/016: {based on manganites}
- C04B 35/44: based on aluminates
- C04B 35/6262: {of calcined, sintered clinker or ceramics}
- C04B 35/62645: {Thermal treatment of powders or mixtures thereof other than sintering}
- C04B 35/62695: {Granulation or pelletising (devices for shaping artificial aggregates from ceramic mixtures B28B1/004)}
- G01K 7/223: {characterised by the shape of the resistive element}
- H01B 1/08: oxides
- C04B 2235/3213: Strontium oxides or oxide-forming salts thereof
- C04B 2235/3217: Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
- C04B 2235/3222: Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
- C04B 2235/3224: Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
- C04B 2235/3225: Yttrium oxide or oxide-forming salts thereof
- C04B 2235/3241: Chromium oxides, chromates, or oxide-forming salts thereof
- C04B 2235/3267: MnO2
- C04B 2235/5436: micrometer sized, i.e. from 1 to 100 micron
- C04B 2235/5445: submicron sized, i.e. from 0,1 to 1 micron
- C04B 2235/604: Pressing at temperatures other than sintering temperatures
- C04B 2235/6567: Treatment time
- C04B 2235/768: Perovskite structure ABO3
- C04B 2235/80: Phases present in the sintered or melt-cast ceramic products other than the main phase
- H01C: RESISTORS
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})

## Abstract

A conductive sintered oxide which includes: a conductive crystal phase having a perovskite structure represented by (RE1-cSrc)MdO3, in which RE is a group of elements consisting of Yb and/or Lu and at least one element selected from Group IIIA elements excluding Yb, Lu and La, and M is a group of elements consisting of Al and at least one element selected from Groups IVA, VA, VIA, VIIA and VIII, a first insulating crystal phase represented by RE2O3, and a second insulating crystal phase represented by SrAl2O4. The conductive crystal phase has a coefficient c satisfying 0.18<c<0.50 and has a coefficient d satisfying 0.67≦d≦0.93. A content of a third insulating crystal phase represented by RE4Al2O9, the content of which may be zero, is smaller than the content of each of the first and second insulating crystal phases.

## Claims

### Claim 1

A conductive sintered oxide which comprises:
a conductive crystal phase having a perovskite structure represented by (RE1-cSrc)MdO3, in which
RE is a group of elements consisting of Yb and/or Lu and at least one element selected from Group IIIA excluding Yb, Lu and La and
M is a group of elements consisting of Al and at least one element Selected from Groups IVA, VA, VIA, VITA and VIII,
a first insulating crystal phase represented by RE2O3, in which RE is as defined above, and
a second insulating crystal phase represented by SrAl2O4, wherein
the conductive crystal phase has a coefficient c which satisfies 0.18<c<0.50,
the conductive crystal phase has a coefficient d satisfying 0.67≦d≦0.93, the coefficient d indicating a ratio between an amount of the element group (RE1-cSrc) constituting A sites and the amount of the element group M constituting B sites of the conductive crystal phase, and
a content of a third insulating crystal phase represented by RE4Al2O9, the content of the third insulating crystal phase represented by RE4Al2O9 not including zero, is smaller than the content of the first insulating crystal phase and is smaller than the content of the second insulating crystal phase.

### Claim 2 (depends on 1)

The conductive sintered oxide as claimed in claim 1, wherein in a cross-section of the conductive sintered oxide, a ratio of an areal proportion of the third insulating crystal phase Si3 to an areal proportion of the conductive crystal phase Sc, Si3/Sc (%), satisfies Si3/Sc≦6.0 (%).

### Claim 3 (depends on 1)

The conductive sintered oxide as claimed in claim 1, wherein the coefficient d satisfies 0.67≦d<0.90.

### Claim 4 (depends on 1)

The conductive sintered oxide according to claim 1, wherein the element group M includes Al, Mn and Cr, and
the conductive crystal phase is represented by (RE1-cSrc)(AlxMnyCrz)O3, in which the coefficients x, y and z (x+y+z=d) satisfy the following
0.40≦x≦0.87
0.05≦y≦0.52
0<z≦0.05.

### Claim 5 (depends on 1)

A thermistor element which comprises the conductive sintered oxide as claimed in claim 1.

### Claim 6 (depends on 5)

A temperature sensor which comprises the thermistor element as claimed in claim 5.