# Patent

## Title
Semiconductor porcelain composition

## Abstract

The invention intends to provide, in BaTiO3 semiconductor porcelain composition, a semiconductor porcelain composition that, without using Pb, can shift the Curie temperature to a positive direction and can significantly reduce the resistivity at room temperature. According to the invention, when Ba is partially substituted by an A1 element (at least one kind of Na, K and Li) and an A2 element (Bi) and Ba is further substituted by a specific amount of a Q element, or when Ba is partially substituted by an A1 element (at least one kind of Na, K and Li) and an A2 element (Bi) and Ti is partially substituted by a specific amount of an M element, the optimal valence control can be applied and whereby the resistivity at room temperature can be significantly reduced. Accordingly, it is optimal for applications in a PTC thermistor, a PTC heater, a PTC switch, a temperature detector and the like, and particularly preferably in an automobile heater.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of PCT International Patent Application No. PCT/JP2005/014769, filed Aug. 11, 2005, and is related to Japanese Patent Application No. 2004-71444, filed Mar. 12, 2004, in the Japanese Patent Office, the disclosures of which are incorporated herein by reference.
TECHNICAL FIELD
The invention relates to a semiconductor porcelain composition for use in a PCT thermistor, a PCT heater, a PCT switch, a temperature detector or the like, which has a positive temperature coefficient of resistivity.
BACKGROUND ART
Conventionally, as materials showing a positive PTCR, there have been proposed compositions in which various semiconductive dopants are added to BaTiO3. Since these compositions have the Curie temperatures around 120° C., these composition need to be shifted in the Curie temperatures depending on the applications.
For example, although it has been proposed to shift Curie temperature by adding SrTiO3 to BaTiO3, in this case, the Curie temperature is shifted only in a negative direction and is not shifted in a positive direction. Only PbTiO3 is known as an additive element for shifting Curie temperature in a positive direction. However, PbTiO3 includes an element for bringing about environmental pollution, and therefore a material which does not use PbTiO3 has been desired in recent years.
In a BaTiO3 semiconductor porcelain, with an object of preventing a reduction in a temperature coefficient of resistivity by Pb substitution, as well as reducing a voltage dependency and promoting a productivity and a reliability, there has been proposed a method of producing a BaTiO3 semiconductor porcelain in which a composition obtained by adding one or more kinds of any of Nb, Ta and a rare earth element to a composition in which x in Ba1−2x (BiNa)xTiO3 where a portion of Ba of BaTiO3 is substituted by Bi—Na is controlled to a range of 0≦x≦0.15, is sintered in nitrogen, and thereafter subjected to a heat treatment in an oxidizing atmosphere.
Patent Reference 1: JP-A-56-169301
DISCLOSURE OF INVENTION
Problem that the Invention is to Solve
In patent reference 1, as an example thereof, a composition obtained by adding 0.1 mol % of Nd2O3 as a semiconductive dopant to Ba1−2x(BiNa)xTiO3 (0<x≦0.15) is disclosed. However, since addition amounts of other Nb and Ta are not at all described, whether a semiconductor is formed or not is unclear.
In this connection, the inventors have made studies on a composition system where Ba is partially substituted by Bi—Na, which is described in patent reference 1, and found that, in the case of conducting a valence control of the composition, when a trivalent positive ion is added as a semiconductive dopant, a semiconductive effect is deteriorated due to the presence of a monovalent Na ion to result in a problem that the resistivity at room temperature becomes higher, and that, even when 0.1 mol % of the Nd2O3 is added as a semiconductive dopant in order to overcome the problem, a semiconductor sufficient for use in PTC cannot be realized.
An object of the invention is to provide a semiconductor porcelain composition which can overcome the problems of the conventional BaTiO3 semiconductor porcelain composition, and is capable of shifting a Curie temperature in a positive direction and considerably reducing a resistivity at room temperature without using Pb.
Means for Solving the Problems
The inventors have paid attention to a valence control when Ba is partially substituted by Bi—Na or the like in a BaTiO3 semiconductor porcelain composition and, as a result of intensive studies on a content of an additive element for carrying out the optimum valence control, found that, when Ba is partially substituted by an A1 element (at least one kind of Na, K and Li) and an A2 element (Bi) and Ba is further substituted by a specific amount of a Q element, the optimum valence control can be carried out and whereby the resistivity at room temperature can be significantly reduced.
Furthermore, the inventors found that, when Ba is partially substituted by an A1 element (at least one kind of Na, K and Li) and an A2 element (Bi) and Ti is partially substituted by a specific amount of an M element, advantages same as the above can be obtained, and that, in this case, with a substitution amount less than a substitution amount with the Q element, the valence control can be advantageously carried out, whereby the invention has been completed.
That is, the invention provides a semiconductor porcelain composition having a composition formula represented by [(A10.5A20.5)x(Ba1−yQy)1−X]TiO3 (in which A1 is at least one kind of Na, K and Li, A2 is Bi, and Q is at least one kind of La, Dy, Eu and Gd), in which x and y each satisfy 0<x≦0.2 and 0.002≦y≦0.01, and more preferably, y satisfies 0.005≦y≦0.01.
Furthermore, the invention also relates to a semiconductor porcelain composition having a composition formula represented by [(A10.5A20.5)xBa1−x][Ti1−zMz]O3 (in which, A1 is at least one kind of Na, K and Li, A2 is Bi, and M is at least one kind of Nb, Ta and Sb), in which x and z each satisfy 0<x≦0.2 and 0<z≦0.01, and more preferably, z satisfies 0<z≦0.005.
Still furthermore, the invention also relates to a semiconductor porcelain composition in which 3.0 mol % or less of a Si oxide and 4.0 mol % or less of a Ca oxide are added in each of the semiconductor porcelain compositions having the above configurations.
Advantage of the Invention
According to the invention, there can be provided, in a BaTiO3 semiconductor porcelain composition, a semiconductor porcelain composition which is capable of shifting the Curie temperature and has a significantly reduced resistivity at room temperature without using Pb which brings about an environmental pollution.
Since the BaTiO3 semiconductor porcelain composition according to the invention has resistivity characteristics in which the resistivity at room temperature and in a range reaching to a predetermined temperature is sufficiently low and, in a target temperature region, the resistivity rapidly becomes higher, it is optimal for applications in a PTC thermistor, a PTC heater, a PTC switch, a temperature detector and the like, and particularly preferably in an automobile heater.


BEST MODE FOR CARRYING OUT THE INVENTION
One of the Characteristics of the invention is that Ba is partially substituted by an A1 element (at least one kind of Na, K and Li) and an A2 element (Bi) to shift the Curie temperature to a positive direction and, in order to optimally control a valence disturbed due to the substitution by A1 and A2 elements, Ba is partially substituted by a specific amount of a Q element (at least one kind of La, Dy, Eu and Gd) to obtain a [(A10.5A20.5)x(Ba1−yQy)1−x]TiO3 composition, or Ti is partially substituted by a specific amount of an M element to obtain a [(A10.5A20.5)xBa1−x][Ti1−zMz]O3 composition.
The reasons of limiting the respective compositions are as follows.
In the [(A10.5A20.5)x(Ba1−yQy)1−x]TiO3 composition, A1 is at least one kind of Na, K and Li, A2 is Bi, and Q is at least one kind of La, Dy, Eu and Gd. Preferably, A1 is Na and Q is La.
In the above-mentioned composition formula, x represents a component range of A1+A2 and is preferably in the range of 0<x≦0.2. When x is zero, the Curie temperature cannot be shifted to a high temperature side, and when x exceeds 0.2, the resistivity at room temperature unfavorably exceeds 103 Ωcm.
Furthermore, in the composition formula, y represents a component range of Q and is preferably in the range of 0.002≦y≦0.01. When y is less than 0.002, the valence control in the composition becomes insufficient and the resistivity at room temperature exceeds 103 Ωcm. Furthermore, when y exceeds 0.01, the composition becomes insulative and the resistivity at room temperature unfavorably exceeds 103 Ωcm. A preferable range thereof is 0.005≦y≦0.01 and, in this case, the resistivity at room temperature can be further reduced. The above range, 0.002≦y≦0.01 is expressed as 0.2 mol % to 1.0 mol % in terms of mol %.
In the [(A10.5A20.5)xBa1−x][Ti1−zMz]O3 composition, A1 is at least one kind of Na, K and Li, A2 is Bi, and M is at least one kind of Nb, Ta and Sb. Preferably, A1 is Na and M is Nb.
In the above-mentioned composition formula, x represents a component range of A1+A2 and is preferably in the range of 0<x≦0.2. When x is zero, the Curie temperature cannot be shifted to a high temperature side, and when it exceeds 0.2, the resistivity at room temperature unfavorably exceeds 103 Ωcm. Furthermore, z represents a component range of M and is preferably in the range of 0<z≦0.01. When z is zero, the valence control cannot be applied and the composition cannot form a semiconductor, and when it exceeds 0.01, the resistivity at room temperature unfavorably exceeds 103 Ωcm. More preferably, z is in the range of 0<z≦0.005. The above range, 0<z≦0.01, is expressed as 0 to 1 mol % (not including 0), in terms of mol %.
In the case of the above-mentioned [(A10.5A20.5)xBa1−x][Ti1−zMz]O3 composition, in order to control the valence, Ti is substituted by an M element. In this case, since an M element is added (preferable addition amount: 0<z≦0.005) in order to control a valence at Ti site that is a tetravalent element, the valence control can be carried out with a smaller amount than an addition amount (0.002≦y≦0.01) of the Q element in the above-mentioned [(A10.5A20.5)x(Ba1−yQy)1−x]TiO3 composition; accordingly, the internal strain of the composition according to the invention can be advantageously alleviated.
In the above-mentioned [(A10.5A20.5)x(Ba1−yQy)1−X]TiO3 composition and [(A10.5A20.5)xBa1−x][Ti1−zMz]O3 composition, the sinterability at low temperature can be improved by adding 3.0 mol % or less of a Si oxide and 4.0 mol % or less of a Ca oxide. When each of the oxides is added exceeding the upper limit, the composition unfavorably does not become a semiconductor.
An example of a process for producing a semiconductor porcelain composition of the invention will be described below.
(1) Oxide powders of the respective elements are prepared, weighed and then mixed.
(2) The mixture is further mixed in pure water or ethanol, and then dried to obtain a mixed powder.
(3) The mixed powder is calcined at a temperature in the range of 900 to 1100° C. for 2 to 6 hr.
(4) The calcined product is pulverized in pure water or ethanol, followed drying.
(5) The pulverized powder is granulated with PVA or the like, and then formed by means of a uniaxial press.
(6) The green compact is degreased at a temperature in the range of 300 to 700° C., and then sintered in air or a reducing atmosphere at a temperature in the range of 1200 to 1450° C. for 2 to 6 hr.
EXAMPLES
Example 1
The respective powders of BaCO3 and TiO2 as main raw materials; La2O3, Dy2O3, Eu2O3, Gd2O3, Nb2O5, Ta2O5 and Sb2O3 as semiconductive dopants; SiO2 and CaO as sintering aides; and (Na2CO3.Bi2O3.TiO2), (K2CO3.Bi2O3.TiO2) and (Li2CO3.Bi2O3.TiO2) as Curie temperature shifters were prepared. These respective powders were blended as shown in Tables 1 through 6, mixed in pure water and then dried to thereby obtain mixed powders having an average particle diameter in the range of 0.6 to 1.2 μm.
In the next place, the mixed powders each were calcined, depending on the compositions, at a temperature in the range of 900 to 1100° C. for 2 to 6 hr. The calcined powders thus obtained each were pulverized in pure water until an average particle diameter becomes in the range of 0.8 to 1.5 μm, and the pulverized powders each were dried. Then, after PVA was added and mixed, the dried powders each were granulated by means of a granulating device.
The granulated powders thus obtained each were formed to have a forming density in the range of 2 to 3 g/cm3 by use of a uniaxial press. The green compacts thus obtained each were degreased at a temperature in the range of 300 to 700° C. and subsequently sintered at a temperature in the range of 1300 to 1360° C. for 4 hr in an atmosphere having an oxygen concentration of 75% to thereby obtain sintered bodies.
The sintered bodies thus obtained each were processed into a plate of 10 mm×10 mm×0.1 mm to thereby obtain test pieces. In the measurement of the resistance of the test piece, a variation of resistance value in a range from room temperature to 200° C. was measured. Measurement results are shown in Tables 1 through 6.
Nos. 1 through 29 in Table 1 show a case of [(A10.5Bi0.5)xBa1−x][Ti1−zNbz]O3 composition; Nos. 30 through 56 in Table 2 show a case of [(A10.5Bi0.5)xBa1−x][Ti1−zSbz]O3 composition; Nos. 57 through 86 in Table 3 show a case of [(A10.5Bi0.5)x(Ba1−yLay)1−X]TiO3 composition; Nos. 87 through 102 in Table 4 show a case of [(A10.5Bi0.5)x(Ba1−yGdy)1−X]TiO3 composition; Nos. 103 through 118 in Table 5 show a case of [(A10.5Bi0.5)x(Ba1−yEuy)1−X]TiO3 composition; and Nos. 119 through 134 in Table 6 show a case of [(A10.5Bi0.5)x(Ba1−yDyy)1−X]TiO3 composition.
Comparative Example 1
In Tables 1 through 6, columns provided with an * mark indicate comparative examples. That is, Nos. 1 through 4 and 11 in Table 1, Nos. 30, 31 and 44 in Table 2, Nos. 57 and 58 in Table 3, Nos. 87 and 88 in Table 4, Nos. 103 and 104 in Table 5 and Nos. 119 and 120 in Table 6 are comparative examples.
Example 2
The respective powders of BaCO3 and TiO2 as main raw materials; La2O3 and Nb2O5 as semiconductive dopants; and (Na2CO3.Bi2O3.TiO2) as the Curie temperature shifter were prepared. The respective powder were blended as shown in Tables 7 and 8, mixed in pure water and then dried to thereby obtain mixed powders having an average particle diameter in the range of 0.6 to 1.2 μm.
In the next place, the mixed powders each were calcined, depending on the compositions, at a temperature in the range of 900 to 1100° C. for 2 to 6 hr. The calcined powders thus obtained each were pulverized in pure water until an average particle diameter becomes in the range of 0.8 to 1.5 μm, and the pulverized powders each were dried. Then, after PVA was added and mixed, the dried powders each were granulated by means of a granulating device.
The granulated powders thus obtained each were formed to have a forming density in the range of 2 to 3 g/cm3 by use of a uniaxial press. The green compacts thus obtained each were degreased at a temperature in the range of 300 to 700° C. and subsequently sintered at a temperature in the range of 1300 to 1360° C. for 4 hr in an atmosphere having an oxygen concentration of 75% to thereby obtain sintered bodies.
The sintered bodies thus obtained each were processed into a plate of 10 mm×10 mm×0.1 mm to thereby obtain test pieces. In the measurement of the resistance of the test piece, a variation of resistance value in a range from room temperature to 200° C. was measured. Measurement results are shown in Tables 7 through 8.
Nos. 135 through 144 in Table 7 show a case of [(A10.5Bi0.5)xBa1−x][Ti1−zNbz]O3 composition and Nos. 145 through 154 in Table 8 show a case of [(A10.5Bi0.5)x(Ba1−yLay)1−x]TiO3 composition.
Comparative Example 2
In Tables 7 through 8, columns provided with an * mark indicate comparative examples. That is, Nos. 135 and 136 in Table 7 and Nos. 145 and 146 in Table 8 are comparative examples.
As obvious from Tables 1 through 8, it is found that semiconductor porcelain compositions according to the invention can elevate the Curie temperature without using Pb and can significantly reduce the resistivity at room temperature.














TABLE 1









A1 =

SiO2
CaO





Na1−a−bKaLib

(mol
(mol
ρ30
Tc















No.
a
b
x
z
%)
%)
(Ωcm)
(° C.)


















 1*
0
0
0
0
0.9
1.9
Insulator
—


 2*
0
0
0
0.002
0.9
1.9
200
110


 3*
0
0
0
0.005
0.9
1.9
3.6
111


 4*
0
0
0
0.01
0.9
1.9
4.1
115


 5
0
0
0.02
0.002
0.9
1.9
150
130


 6
0
0
0.02
0.005
0.9
1.9
119
130


 7
0
0
0.02
0.01
0.9
1.9
131
135


 8
0
0
0.06
0.002
0.9
1.9
91
160


 9
0
0
0.06
0.005
0.9
1.9
73
160


10
0
0
0.06
0.01
0.9
1.9
86
163


11*
0
0
0.06
0.012
0.9
1.9
89
161


12
0
0
0.1
0.002
0.9
1.9
93
173


13
0
0
0.1
0.005
0.9
1.9
84
173


14
0
0
0.1
0.01
0.9
1.9
97
175


15
0
0
0.2
0.002
0.9
1.9
156
181


16
0
0
0.2
0.005
0.9
1.9
93
181


17
0
0
0.2
0.01
0.9
1.9
128
183


18
0.4
0
0.02
0.005
0.9
1.9
78
125


19
0.4
0
0.06
0.005
0.9
1.9
89
154


20
0.4
0
0.1
0.005
0.9
1.9
55
162


21
0.4
0
0.2
0.005
0.9
1.9
82
176


22
0.8
0
0.02
0.005
0.9
1.9
86
120


23
0.8
0
0.06
0.005
0.9
1.9
99
141


24
0.8
0
0.1
0.005
0.9
1.9
78
153


25
0.8
0
0.2
0.005
0.9
1.9
98
166


26
0.2
0.2
0.02
0.005
0.9
1.9
70
121


27
0.2
0.2
0.06
0.005
0.9
1.9
81
139


28
0.2
0.2
0.1
0.005
0.9
1.9
49
150


29
0.2
0.2
0.2
0.005
0.9
1.9
100
162























TABLE 2









A1 =

SiO2
CaO





Na1−a−bKaLib

(mol
(mol
ρ30
Tc















No.
a
b
x
z
%)
%)
(Ωcm)
(° C.)


















30*
0
0
0
0
0.9
1.9
Insulator
—


31*
0
0
0
0.005
0.9
1.9
3.6
110


32
0
0
0.02
0.002
0.9
1.9
54
129


33
0
0
0.02
0.005
0.9
1.9
31
130


34
0
0
0.02
0.01
0.9
1.9
85
133


35
0
0
0.06
0.002
0.9
1.9
92
158


36
0
0
0.06
0.005
0.9
1.9
80
160


37
0
0
0.06
0.01
0.9
1.9
96
163


38
0
0
0.1
0.002
0.9
1.9
90
173


39
0
0
0.1
0.005
0.9
1.9
98
172


40
0
0
0.1
0.01
0.9
1.9
102
172


41
0
0
0.2
0.002
0.9
1.9
210
181


42
0
0
0.2
0.005
0.9
1.9
111
180


43
0
0
0.2
0.01
0.9
1.9
318
181


44*
0
0
0.25
0.005
0.9
1.9
Insulator
—


45
0.4
0
0.02
0.005
0.9
1.9
47
121


46
0.4
0
0.06
0.005
0.9
1.9
34
149


47
0.4
0
0.1
0.005
0.9
1.9
22
162


48
0.4
0
0.2
0.005
0.9
1.9
84
177


49
0.8
0
0.02
0.005
0.9
1.9
76
122


50
0.8
0
0.06
0.005
0.9
1.9
74
141


51
0.8
0
0.1
0.005
0.9
1.9
79
152


52
0.8
0
0.2
0.005
0.9
1.9
168
164


53
0.2
0.2
0.02
0.005
0.9
1.9
101
118


54
0.2
0.2
0.06
0.005
0.9
1.9
105
137


55
0.2
0.2
0.1
0.005
0.9
1.9
92
148


56
0.1
0.2
0.2
0.005
0.9
1.9
168
160























TABLE 3









A1 =

SiO2
CaO





Na1−a−bKaLib

(mol
(mol
ρ30
Tc















No.
a
b
x
y
%)
%)
(Ωcm)
(° C.)


















57*
0
0
0
0
0.9
1.9
Insulator
—


58*
0
0
0
0.005
0.9
1.9
233
110


59
0
0
0.02
0.002
0.9
1.9
61
132


60
0
0
0.02
0.005
0.9
1.9
49
132


61
0
0
0.02
0.008
0.9
1.9
29
132


62
0
0
0.02
0.001
0.9
1.9
63
134


63
0
0
0.06
0.002
0.9
1.9
83
161


64
0
0
0.06
0.005
0.9
1.9
59
162


65
0
0
0.06
0.008
0.9
1.9
41
161


66
0
0
0.06
0.01
0.9
1.9
50
162


67
0
0
0.1
0.002
0.9
1.9
56
170


68
0
0
0.1
0.005
0.9
1.9
78
170


69
0
0
0.1
0.008
0.9
1.9
79
171


70
0
0
0.1
0.01
0.9
1.9
80
173


71
0
0
0.2
0.002
0.9
1.9
36
179


72
0
0
0.2
0.005
0.9
1.9
58
179


73
0
0
0.2
0.008
0.9
1.9
54
181


74
0
0
0.2
0.01
0.9
1.9
76
182


75
0.4
0
0.02
0.005
0.9
1.9
53
122


76
0.4
0
0.06
0.005
0.9
1.9
97
151


77
0.4
0
0.1
0.005
0.9
1.9
99
159


78
0.4
0
0.2
0.005
0.9
1.9
125
172


79
0.8
0
0.02
0.005
0.9
1.9
56
119


80
0.8
0
0.06
0.005
0.9
1.9
91
139


81
0.8
0
0.1
0.005
0.9
1.9
140
150


82
0.8
0
0.2
0.005
0.9
1.9
126
164


83
0.2
0.2
0.02
0.005
0.9
1.9
59
123


84
0.2
0.2
0.06
0.005
0.9
1.9
68
137


85
0.2
0.2
0.1
0.005
0.9
1.9
151
153


86
0.2
0.2
0.2
0.005
0.9
1.9
160
163























TABLE 4









A1 =

SiO2
CaO





Na1−a−bKaLib

(mol
(mol
ρ30
Tc















No.
a
b
x
y
%)
%)
(Ωcm)
(° C.)


















 87*
0
0
0
0
0.9
1.9
Insulator
—


 88*
0
0
0
0.005
0.9
1.9
23
112


 89
0
0
0.02
0.005
0.9
1.9
28
133


 90
0
0
0.02
0.01
0.9
1.9
91
131


 91
0
0
0.06
0.005
0.9
1.9
44
160


 92
0
0
0.06
0.01
0.9
1.9
87
162


 93
0
0
0.1
0.005
0.9
1.9
56
171


 94
0
0
0.1
0.01
0.9
1.9
99
171


 95
0
0
0.2
0.005
0.9
1.9
89
177


 96
0
0
0.2
0.01
0.9
1.9
119
181


 97
0.4
0
0.06
0.005
0.9
1.9
67
150


 98
0.4
0
0.2
0.005
0.9
1.9
72
170


 99
0.8
0
0.06
0.005
0.9
1.9
66
141


100
0.8
0
0.2
0.005
0.9
1.9
96
165


101
0.2
0.2
0.06
0.005
0.9
1.9
97
139


102
0.2
0.2
0.2
0.005
0.9
1.9
72
164























TABLE 5









A1 =

SiO2
CaO





Na1−a−bKaLib

(mol
(mol
ρ30
Tc















No.
a
b
x
y
%)
%)
(Ωcm)
(° C.)


















103*
0
0
0
0
0.9
1.9
Insulator
—


104*
0
0
0
0.005
0.9
1.9
48
110


105
0
0
0.02
0.005
0.9
1.9
66
129


106
0
0
0.02
0.01
0.9
1.9
100
129


107
0
0
0.06
0.005
0.9
1.9
79
159


108
0
0
0.06
0.01
0.9
1.9
136
160


109
0
0
0.1
0.005
0.9
1.9
71
169


110
0
0
0.1
0.01
0.9
1.9
118
171


111
0
0
0.2
0.005
0.9
1.9
78
175


112
0
0
0.2
0.01
0.9
1.9
155
179


113
0.4
0
0.06
0.005
0.9
1.9
99
151


114
0.4
0
0.2
0.005
0.9
1.9
225
169


115
0.8
0
0.06
0.005
0.9
1.9
98
140


116
0.8
0
0.2
0.005
0.9
1.9
264
165


117
0.2
0.2
0.06
0.005
0.9
1.9
117
140


118
0.2
0.2
0.2
0.005
0.9
1.9
310
166























TABLE 6









A1 =

SiO2
CaO





Na1−a−bKaLib

(mol
(mol
ρ30
Tc















No.
a
b
x
y
%)
%)
(Ωcm)
(° C.)


















119*
0
0
0
0
0.9
1.9
Insulator
—


120*
0
0
0
0.005
0.9
1.9
122
111


121
0
0
0.02
0.005
0.9
1.9
127
130


122
0
0
0.02
0.01
0.9
1.9
399
129


123
0
0
0.06
0.005
0.9
1.9
94
163


124
0
0
0.06
0.01
0.9
1.9
392
164


125
0
0
0.1
0.005
0.9
1.9
100
170


126
0
0
0.1
0.01
0.9
1.9
490
169


127
0
0
0.2
0.005
0.9
1.9
101
174


128
0
0
0.2
0.01
0.9
1.9
323
182


129
0.4
0
0.06
0.005
0.9
1.9
112
152


130
0.4
0
0.2
0.005
0.9
1.9
438
171


131
0.8
0
0.06
0.005
0.9
1.9
125
140


132
0.8
0
0.2
0.005
0.9
1.9
482
164


133
0.2
0.2
0.06
0.005
0.9
1.9
149
141


134
0.2
0.2
0.2
0.005
0.9
1.9
587
163























TABLE 7









A1 =

SiO2
CaO





Na1−a−bKaLib

(mol
(mol
ρ30
Tc















No.
a
b
x
z
%)
%)
(Ωcm)
(° C.)


















135*
0
0
0
0
0
0
Insulator
—


136*
0
0
0
0.005
0
0
88
110


137
0
0
0.02
0.005
0
0
94
132


138
0
0
0.02
0.01
0
0
108
131


139
0
0
0.06
0.005
0
0
81
161


140
0
0
0.06
0.01
0
0
184
165


141
0
0
0.1
0.005
0
0
116
169


142
0
0
0.1
0.01
0
0
141
170


143
0
0
0.2
0.005
0
0
109
176


144
0
0
0.2
0.01
0
0
186
183























TABLE 8









A1 =

SiO2
CaO





Na1−a−bKaLib

(mol
(mol
ρ30
Tc















No.
a
b
x
y
%)
%)
(Ωcm)
(° C.)


















145*
0
0
0
0
0
0
Insulator
—


146*
0
0
0
0.005
0
0
333
111


147
0
0
0.02
0.002
0
0
82
131


148
0
0
0.02
0.005
0
0
72
131


149
0
0
0.02
0.008
0
0
69
132


150
0
0
0.02
0.001
0
0
91
133


151
0
0
0.06
0.002
0
0
103
161


152
0
0
0.06
0.005
0
0
88
160


153
0
0
0.06
0.008
0
0
70
161


154
0
0
0.06
0.01
0
0
86
160









INDUSTRIAL APPLICABILITY
According to the semiconductor porcelain composition of the invention, since the Curie temperature can be elevated and the resistivity at room temperature can be significantly reduced without using Pb that causes an environmental pollution, it can be utilized in a PTC thermistor, a PTC heater, a PTC switch, a temperature detector and the like. In particular, it is optimal for applications in automobile heaters and the like, in which an adverse affect on human bodies is feared.

## Claims

1. A semiconductor porcelain composition having a composition formula represented by [(A10.5A20.5)x(Ba1−yQy)1−x]TiO3, wherein A1 is at least one of Na, K and Li, A2 is Bi, and Q is at least one of La, Dy, Eu and Gd, and
wherein x and y each satisfy 0<x≦0.2 and 0.002≦y≦0.01.

2. The semiconductor porcelain composition according to claim 1, wherein y satisfies 0.005≦y≦0.01.

3. The semiconductor porcelain composition according to claim 1, wherein 3.0 mol % or less of a Si oxide and 4.0 mol % or less of a Ca oxide are added.