Sintered electroconductive oxide, thermister element using sintered electroconductive oxide, and temperature sensor using thermister element

• US 20090016409A1
• Filed: 04/11/2006
• Published: 01/15/2009
• Est. Priority Date: 04/11/2005
• Status: Active Grant

• Current Assignee: NGK Spark PLUG Company Limited (Niterra Co., Ltd.)
• Original Assignee: NGK Spark PLUG Company Limited (Niterra Co., Ltd.)
• Inventors: Ohbayashi, Kazushige, Mitsuoka, Takeshi, Okimura, Yasuyuki, Mizoguchi, Yoshihito
• Granted Patent: US 7,656,269 B2
• Time in Patent Office: Days
• US Class Current: 374/185
• CPC Class Codes: C01G 45/125 of the type[MnO3]n-, e.g. Li2MnO3, Li2[MxMn1-xO3], (La,Sr)MnO3
• CPC Class Codes: C01G 45/1264 containing rare earth, e.g. La1-xCaxMnO3, LaMnO3
• CPC Class Codes: C01G 49/009 Compounds containing, besides iron, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01P 2002/34 perovskite-type (ABO3)
• CPC Class Codes: C01P 2002/50 Solid solutions
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3222 Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3239 Vanadium oxides, vanadates or oxide forming salts thereof, e.g. magnesium vanadate
• CPC Class Codes: C04B 2235/3243 Chromates or chromites, e.g. aluminum chromate, lanthanum strontium chromite
• CPC Class Codes: C04B 2235/3262 Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/3272 Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/785 : Submicron sized grains, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/786 : Micrometer sized grains, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/79 : Non-stoichiometric products, e.g. perovskites (ABO3) with an A/B-ratio other than 1
• CPC Class Codes: C04B 2235/80 : Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 2235/94 : Products characterised by their shape
• CPC Class Codes: C04B 2235/95 : Products characterised by their size, e.g. microceramics
• CPC Class Codes: C04B 35/016 : based on manganites
• CPC Class Codes: C04B 35/2641 : Compositions containing one or more ferrites of the group comprising rare earth metals and one or more ferrites of the group comprising alkali metals, alkaline earth metals or lead
• CPC Class Codes: C04B 35/44 : based on aluminates
• CPC Class Codes: C04B 35/6262 : of calcined, sintered clinker or ceramics
• CPC Class Codes: G01K 1/08 : Protective devices, e.g. casings
• CPC Class Codes: G01K 2205/04 : for measuring exhaust gas temperature
• CPC Class Codes: G01K 7/22 : the element being a non-linear resistance, e.g. thermistor G01K7/26 takes precedence
• CPC Class Codes: H01B 1/08 : oxides
• CPC Class Codes: H01C 17/06533 : composed of oxides
• CPC Class Codes: H01C 7/025 : Perovskites, e.g. titanates
• CPC Class Codes: H01C 7/045 : Perovskites, e.g. titanates

Abstract

According to an aspect of the present invention, there is provided a sintered electroconductive oxide containing a perovskite phase of perovskite-type crystal structure represented by the composition formula: M1_aM2_bM3_cAl_dCr_eO_f where M1 is at least one of elements of group 3A other than La; M2 is at least one of elements of group 2A; M3 is at least one of elements of groups 4A, 5A, 6A, 7A and 8 other than Cr; and a, b, c, d, e and f satisfy the following conditional expressions:

0.600≦a≦1.000;

0≦b≦0.400;

0.150≦c<0.600;

0.400≦d≦0.800;

0<e≦0.050;

0<e/(c+e)≧0.18; and

2.80≦f≦3.30.

With the use of this conductive oxide sintered body, it becomes possible to carry out proper temperature measurements over the temperature range from a low temperature of −40° C. to a high temperature of 900° C. or higher.

Claims

1. A sintered electroconductive oxide containing a perovskite phase of perovskite-type crystal structure represented by the composition formula:

M1_aM2_bM3_cAl_dCr_eO_f where M1 is at least one of elements of group 3A other than La;

M2 is at least one of elements of group 2A;

M3 is at least one of elements of groups 4A, 5A, 6A, 7A and 8 other than Cr; and

a, b, c, d, e and f satisfy the following conditional expressions;

0.600≦

a≦

1.000;

0≦

b≦

0.400;

0.150≦

c<

0.600;

0.400≦

d≦

0.800;

0≦

e≦

0.050;

0<

e/(c+e)≦

0.18; and

2.80≦

f≦

3.30.

2. The sintered electroconductive oxide according to claim 1, wherein a and b satisfy the following conditional expressions:

0.600≦

a<

1.000; and

0≦

b≦

0.400.

3. The sintered electroconductive oxide according to claim 2, wherein a, b, c, d, e and f satisfy the following conditional expressions:

0.820≦

a≦

0.950;

0.050≦

b≦

0.180;

0.181≦

c≦

0.585;

0.410≦

d≦

0.790;

0.005≦

e≦

0.050;

0<

e/(c+e)≦

0.18; and

2.91≦

f≦

3.27.

4. The sintered electroconductive oxide according to claim 2, wherein M1 is one or more elements selected from Y, Nd, Yb;

M2 is one or more elements selected from Mg, Ca and Sr; and

M3 is one or more elements selected from Mn and Fe.

5. The sintered electroconductive oxide according to claim 4, wherein M1 is Y;

M2 is Sr; and

M3 is Mn.

6. The sintered electroconductive oxide according to claim 1, further having at least one metal oxide phase being lower in electrical conductivity than the perovskite phase and having a crystal structure represented by the composition formula:

MeO_x where Me is at least one selected from the metal elements of the perovskite phase.

7. The sintered electroconductive oxide according to claim 6, satisfying the following expression:

0.20≦

SP/S≦

0.80 where S is the area of a cross section of the sintered electroconductive oxide; and

SP is the total cross section area of the perovskite phase appearing on the cross section of the sintered electroconductive oxide.

8. The sintered electroconductive oxide according to claim 6, wherein the metal oxide phase contains a complex oxide.

9. The sintered electroconductive oxide according to claim 8, wherein a and b satisfy the following conditional expressions;

and the metal oxide phase contains a complex oxide of the elements M1 and M2;

0.600≦

a<

1.000; and

0≦

b≦

0.400.

10. The sintered electroconductive oxide according to claim 9, wherein the element M1 contains Y;

the element M2 contains Sr; and

the metal oxide phase contains a complex oxide represented by the composition formula;

SrY₂O₄.

11. The sintered electroconductive oxide according to claim 8, wherein a and b satisfy the following conditional expressions;

and the metal oxide phase contains a complex oxide of at least either one of the elements M1 and M2 and at least one of either one of the element M3, Al and Cr;

0.600≦

a<

1.000; and

0<

b≦

0.400.

12. The sintered electroconductive oxide according to claim 11, wherein the element M2 contains Sr;

and the metal oxide phase contains a complex oxide represented by the composition formula;

SrAl₂O₄.

13. A thermistor element using the sintered electroconductive oxide according to claim 1.

14. The thermistor element according to claim 13, having a reduction-resistant coating covering the sintered electroconductive oxide.

15. A temperature sensor using the thermistor element according to claim 13.

16. A sintered electroconductive oxide containing a perovskite phase of perovskite-type crystal structure represented by the composition formula:

M1_aM2_bM3_cAl_dCr_eO_f where M1 is at least one of elements of group 3A other than La;

M2 is at least one of elements of group 2A;

M3 is at least one of elements of groups 4A, 5A, 6A, 7A and 8 other than Cr; and

a, b, c, d, e and f satisfy the following conditional expressions;

0.600≦

a≦

1.000;

0≦

b≦

0.400;

0.150≦

c<

0.600;

0.400≦

d≦

0.800;

0<

e≦

0.050;

0<

e/(c+e)≦

0.18; and

2.80≦

f≦

3.30,

the sintered electroconductive oxide having a temperature gradient constant of 2000 to 3000 K in a temperature range of −

40°

C. to 900°

C.