Thermistor sintered body and thermistor element

• US 10,643,768 B2
• Filed: 04/27/2018
• Issued: 05/05/2020
• Est. Priority Date: 06/20/2017
• Status: Active Grant

• Current Assignee: Shibaura Electronics Company Limited
• Original Assignee: Shibaura Electronics Company Limited
• Inventors: Takeuchi, Akitaka, Niizeki, Naohiro
• Primary Examiner(s): Lee, Kyung S
• Application Number:
  US16/475,944
• Publication Number:
  US 20190348201A1
• Time in Patent Office: 739 Days
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3241 Chromium oxides, chromates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3263 Mn3O4
• CPC Class Codes: C04B 2235/442 Carbonates
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/6567 Treatment time
• CPC Class Codes: C04B 2235/661 Multi-step sintering
• CPC Class Codes: C04B 35/505 based on yttrium oxide
• CPC Class Codes: C04B 35/64 Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: H01C 17/06533 composed of oxides
• CPC Class Codes: H01C 7/008 Thermistors H01C7/02 - H01C7/06 take precedence
• CPC Class Codes: H01C 7/043 Oxides or oxidic compounds
• CPC Class Codes: H01C 7/06 including means to minimise changes in resistance with changes in temperature

Abstract

A thermistor sintered body that can control a B constant at 1000° C. to the same level as that of a conventional wide range type. The thermistor sintered body according to the present invention has a composite structure that includes a Y₂O₃ phase and a Y(Cr, Mn)O₃ phase or a YMnO₃ phase. In the thermistor sintered body according to one aspect of the present invention, a chemical composition of Cr, Mn, Ca and Y excluding oxygen is Cr: 3 to 9 mol %, Mn: 5 to 15 mol %, Ca: 1 to 8 mol % (where Cr/Mn<1.0), and the balance being unavoidable impurities and Y. In the thermistor sintered body, the B constant (B(0/1000)) determined by the following Expression (1) is 2400 K or lower; B=(lnRm−lnRn)/(1/Tm−1/Tn) . . . (1). Rm: resistance value at 0° C., Rn: resistance value at 1000° C., Tm: 0° C., and Tn: 1000° C.

Claims

1. A thermistor sintered body comprising a sintered body that comprises a Y₂O₃ phase and a Y(Cr, Mn)O₃ phase or a YMnO₃ phase, and is rich in Mn relative to Cr, wherein

a B constant (B(0/1000)) determined by the following expression is 2400 K or lower;

B=(lnRm−

lnRn)/(1/Tm−

1/Tn), wherein

Rm;

resistance value at 0°

C.,

Rn;

resistance value at 1000°

C.,

Tm;

0°

C., and

Tn;

1000°

C.

2. The thermistor sintered body according to claim 1, wherein

the sintered body comprises the Y₂O₃ phase and the Y(Cr, Mn)O₃ phase;

and

a chemical composition of Cr, Mn, Ca and Y excluding oxygen is Cr;

3 to 9 mol %, Mn;

5 to 15 mol %, Ca;

1 to 8 mol % (wherein Cr/Mn<

1.0), and the balance being unavoidable impurities and Y, wherein

Cr/Mn is 0.4 to 0.9.

3. A thermistor element comprising:

a heat sensitive body;

a pair of lead wires electrically connected to the heat sensitive body; and

a covering layer covering the heat sensitive body, wherein

the heat sensitive body comprises the thermistor sintered body according to claim 2.

4. The thermistor sintered body according to claim 1, wherein

Ca dissolves in the Y(Cr, Mn)O₃ phase or in the YMnO₃ phase.

5. A thermistor element comprising:

a heat sensitive body;

a pair of lead wires electrically connected to the heat sensitive body; and

a covering layer covering the heat sensitive body, wherein

the heat sensitive body comprises the thermistor sintered body according to claim 4.

6. The thermistor sintered body according to claim 1, comprising a crystal structure of an orthorhombic crystal system.

7. A thermistor element comprising:

a heat sensitive body;

a pair of lead wires electrically connected to the heat sensitive body; and

a covering layer covering the heat sensitive body, wherein

the heat sensitive body comprises the thermistor sintered body according to claim 6.

8. The thermistor sintered body according to claim 1, wherein

a B constant (B(−

40/25)) determined by the following expression is 2200 K or lower;

B=(lnRm−

lnRn)/(1/Tm−

1/Tn), wherein

Rm;

resistance value at −

40°

C.,

Rn;

resistance value at 25°

C.,

Tm;

−

40°

C., and

Tn;

25°

C.

9. A thermistor element comprising:

a heat sensitive body;

a pair of lead wires electrically connected to the heat sensitive body; and

a covering layer covering the heat sensitive body, wherein

the heat sensitive body comprises the thermistor sintered body according to claim 8.

10. The thermistor sintered body according to claim 1, wherein

a B constant (B(25/600)) determined by the following expression is 2300 K or lower;

B=(lnRm−

lnRn)/(1/Tm−

1/Tn), wherein

Rm;

resistance value at 25°

C.,

Rn;

resistance value at 600°

C.,

Tm;

25°

C., and

Tn;

600°

C.

11. The thermistor sintered body according to claim 1, wherein

a B constant (B(600/1000)) determined by the following expression is 2800 K or lower;

B=(lnRm−

lnRn)/(1/Tm−

1/Tn), wherein

Rm;

resistance value at 600°

C.,

Rn;

resistance value at 1000°

C.,

Tm;

600°

C., and

Tn;

1000°

C.

12. The thermistor sintered body according to claim 1, wherein

a resistance value at 1050°

C. is 0.05 kΩ

or larger.

13. A thermistor element comprising:

a heat sensitive body;

a pair of lead wires electrically connected to the heat sensitive body; and

a covering layer covering the heat sensitive body, wherein

the heat sensitive body comprises the thermistor sintered body according to claim 12.

14. The thermistor sintered body according to claim 1, wherein

a resistance value of 100 kΩ

is exhibited at room temperature or lower.

15. A thermistor element comprising:

a heat sensitive body;

a pair of lead wires electrically connected to the heat sensitive body; and

a covering layer covering the heat sensitive body, wherein

the heat sensitive body comprises the thermistor sintered body according to claim 14.

16. A thermistor element comprising:

a heat sensitive body;

a pair of lead wires electrically connected to the heat sensitive body; and

a covering layer covering the heat sensitive body, wherein

the heat sensitive body comprises the thermistor sintered body according to claim 1.

17. A thermistor sintered body comprising a sintered body that comprises a Y₂O₃ phase and a Y(Cr, Mn)O₃ phase, and is rich in Mn relative to Cr, wherein

a B constant (B(0/1000)) determined by the following expression is 2400 K or lower;

B=(lnRm−

lnRn)/(1/Tm−

1/Tn), wherein

Rm;

resistance value at 0°

C.,

Rn;

resistance value at 1000°

C.,

Tm;

0°

C., and

Tn;

1000°

C., wherein

a chemical composition of Cr, Mn, Ca and Y excluding oxygen is Cr;

≤

mol % (excluding

     0), Mn;

12 to 23 mol %, Ca;

6 to 18 mol %, and the balance being unavoidable impurities and Y, and wherein

Cr/Mn is 0.5 or smaller (excluding

     0).

18. A thermistor element comprising:

a heat sensitive body;

a pair of lead wires electrically connected to the heat sensitive body; and

a covering layer covering the heat sensitive body, wherein

the heat sensitive body comprises the thermistor sintered body according to claim 17.

19. A thermistor sintered body comprising a sintered body that comprises a Y₂O₃ phase and a YMnO₃ phase, and is rich in Mn relative to Cr, wherein

a B constant (B(0/1000)) determined by the following expression is 2400 K or lower;

B=(lnRm−

lnRn)/(1/Tm−

1/Tn), wherein

Rm;

resistance value at 0°

C.,

Rn;

resistance value at 1000°

C.,

Tm;

0°

C., and

Tn;

1000°

C., and wherein

a chemical composition of Mn, Ca and Y excluding oxygen is Mn;

12 to 18 mol %, Ca;

6 to 18 mol %, and the balance being unavoidable impurities and Y.

20. A thermistor element comprising:

a heat sensitive body;

a pair of lead wires electrically connected to the heat sensitive body; and

a covering layer covering the heat sensitive body, wherein

the heat sensitive body comprises the thermistor sintered body according to claim 19.