JP3391190B2 - Thermistor composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to a method for producing rare earth elements
Composite oxide of various elements and perovskite type
Including a substance that has a structure, temperature over a wide temperature range (absolute temperature
The relationship between the reciprocal of degree) and the logarithm of resistance was excellent in linearity.
Service that can be used effectively for temperature sensors, etc.
The present invention relates to a mister composition. [0002] 2. Description of the Related Art Within a range of several hundred degrees to about 1000 degrees.
Temperature measuring instruments for measuring temperature include thermocouples and
Thermistors are widely used. Thermocouple and thermistor
Thermocouples have a higher measured temperature than thermistors.
Although it has the advantage of a wide range, it has the following disadvantages
ing.   Low noise immunity.   Low high temperature durability.   Since a complicated circuit such as an amplifier circuit is required,
I can't make it. Therefore, it is necessary to measure a wide range of temperature like a thermocouple.
A thermistor that is
Temperature measurement can be performed inexpensively over a long period of time.
You. Conventionally, various thermistor compositions
Has been proposed. For example, JP-A-7-201528
In the gazette, A is excluded from Group 2a and La of the periodic table of elements.
At least one element selected from elements belonging to Group 3a
Elementary, M¹Is selected from Cr, Mn, Co and Ni.
At least one element, M^TwoWith Fe or part of Fe with Al
Y and Z are defined as 0.05 ≦ Y / (1-Y
-Z) ≦ 0.4 and 0.025 ≦ Z ≦ 0.35
Formula A (M '_1-YZM^Two _YT
i_Z) O_ThreeHigh for detecting high temperature
Shows characteristics that are stable at temperature and can be used in both oxidation and reduction atmospheres.
A porcelain composition for a thermistor is disclosed. [0004] SUMMARY OF THE INVENTION
Patent application title: Porcelain for thermistor disclosed in Japanese Patent Application Publication No. 7-201528
Temperature (absolute temperature) over a wide temperature range, even for compositions
The linearity of the relationship between the reciprocal and the logarithm of the resistance is not sufficient. So
Therefore, more reliable temperature measurement over a wide temperature range
Thermistor compositions that can perform
Was. That is, specifically, the thermistor constant (B value) is
3000-8000 [K], over a wide temperature range
Good linearity of thermistor characteristics and excellent heat resistance
There has been a strong demand for improved thermistor compositions. [0005] The present invention solves the problems of the prior art.
For a wide temperature range
Reciprocal of temperature (absolute temperature) and logarithm of resistivity over area
Is highly linear, and therefore can be used as a thermistor.
Accurate temperature measurement over a wide temperature range when used
A thermistor composition as described above which can
Is to provide. [0006] SUMMARY OF THE INVENTION The thermistor composition of the present invention
The material is a small amount of yttrium (Y) and rare earth elements.
At least one element (referred to as A) and magnesium (M
g), calcium (Ca), strontium (Sr),
At least one element of barium (Ba) (Q and
) And vanadium (V) and iron (Fe)
At least one element (M) and chromium (Cr)
Composite oxide of various elements and perovskite type
Thermistor composition consisting of a substance containing a crystal structure
And the atomic ratio of Cr to the sum of Cr and the element M;
(I): Cr / (Cr + M) (I) Is the following formula (I) ′: 0.35 ≦ Cr / (Cr + M) ≦ 0.65 (I) ′ And the sum of element A and element Q
Atomic ratio of element Q to Q / (A + Q) (II) Is the following formula (II) ′: 0 <Q / (A + Q) <0.04 (II) ' And the element A, the element Q and the element M
Atom of the sum of element A and element Q with respect to the sum of
Ratio; the following formula (III): (A + Q) / (A + Q + M + Cr) (III) Is the following formula (III) ′:     0.4 ≦ (A + Q) / (A + Q + M + Cr) ≦ 0.6 (III) ′ Is within the numerical range represented by [0007] Temperature measurement is possible over a wide temperature range.
To obtain a high thermistor, a thermistor composition
Ideally within the measurement temperature range
, The thermistor constant (B value) is constant and the measurement range
The ratio of the resistivity at the highest temperature to the resistivity at the lowest temperature is 10
It is desirable to be in the range of 0 to 500. For example, measurement
Medium to high temperature range (300 to 900 ° C, desired range)
Or a wide temperature range of 200 to 1000 ° C.)
The value is 3000 to 8000 [K], preferably 4000 to 8000 [K].
It is desirable to be 6000 [K]. Such a sir
The atomic ratio of the element M to Cr [C
r / (Cr + M); Formula (I)] is represented by Formula (I) ′.
To the sum of the elements A and Q
The atomic ratio of the element Q [Q / (A + Q);
I) limited to the numerical range represented by '), element A and element Q
Of element A and element Q with respect to the sum of
Total atomic ratio [(A + Q) / (A + Q + M + Cr);
(III)] to the numerical range represented by formula (III) '
did. The value of equation (I) is a number represented by equation (I) '
In the thermistor composition outside the value range, the amount of change in the B value is
Or B value compared to the above composition
Substantially deviates from the desired value, so that substantially
Thermistor with high measurement accuracy and capable of measuring temperature over a wide temperature range
You can't get a star. The value of equation (II) (> 0) is too large
And, the resistivity of the composition is too small, thermistor characteristics,
In some cases, the thermistor composition is inappropriate. Concrete
More specifically, when the formula (II) ≧ 0.04, the B value becomes small, and
Therefore, due to the thermistor characteristics, it is not suitable as a thermistor composition.
May be appropriate. For this reason, the thermistor composition
And the value of equation (II) is greater than 0 and less than 0.04 [equation
(II). The value of formula (III) is less than 0.4 or
If it exceeds 0.6, it is unsuitable as a thermistor composition.
Cases arise. Specifically, for example, if M is V,
Cerite-type crystal structures other than the lobskite-type crystal structures
Perovskite when M is Fe
Crystal grains having a crystal structure other than the type crystal structure are secondary
May be formed in the composition and its amount may increase,
In such cases, thermistor characteristics may be adversely affected
There is. Therefore, in the present thermistor composition, the formula
The value of (III) is 0.4 or more and 0.6 or less [formula (III) ′
Numerical range represented by. The existence of each element constituting the thermistor composition
As a simple analysis method for measuring the presence ratio, for example, E
PMA (Electron Probe Micro Analysis)
You. Also, a method for identifying the crystal structure of the composite oxide [Perovska
Method for identifying a site-type structure]
Usually, the powder X-ray diffraction method is used. [0012] BEST MODE FOR CARRYING OUT THE INVENTION In the present thermistor composition,
The expression (II) is expressed as follows: 0.001 ≦ Q / (A + Q) ≦ 0.03
It is desirable to be within the numerical range represented by Within this range
Then, the amount of change in the B value becomes even smaller. In addition, this service
For adjusting the thermistor characteristics
Aluminum that can increase the B value appropriately
(Al) may be added. In this case, Al and Cr
Atomic ratio of Al to the sum of element M and the following formula (IV): Al / (Al + Cr + M) (IV) Is the following equation (IV) ′: 0 <Al / (Al + Cr + M) ≦ 0.10 (IV) ′ It is desirable to be within the numerical range represented by Less than this amount
When Al is added on top, the B value of the thermistor composition increases.
May become too much. As described above, the perovskite-type crystal structure
The use of a substance containing crystalline particles
A constant thermistor composition is obtained. In addition, this service
Mister compositions have a crystal structure other than the perovskite type.
May be included. For example, perovskite crystal structure
Crystal grains mainly having a partially celite type crystal structure
It may be a substance containing crystalline particles having a structure. Perovska
It is desirable that the proportion of the crystal structure of the site type is 50% by volume or more.
No. Perovskite type crystal structure is present in 50 volumes
%, The thermistor characteristics may be unstable.
You. The present composition comprises an oxide of each component element (for example,
Y_TwoO_Three, CaCO_Three, V_TwoO_Five, Cr_TwoO_ThreeEtc.)
It can be easily manufactured. The oxide material is a commercial product
May be used as is. If desired, further additives
May be added. Specifically, the thermistor of the present invention will be described below.
An example of a method for producing the composition will be described. Predetermined commercial raw materials
Weigh them to obtain the ratio, mix them with a ball mill,
After grinding and drying, the required amount of powder obtained is then reduced to the desired shape.
And then calcined. Powder this again with a ball mill
Crush and dry. The required amount of the obtained powder is converted into a suitable shape
(For example, into a disc) and then fired in air
(For example, firing in air at 1600 ° C. for 2 hours)
) To obtain a sintered body. The thermistor using the present composition is flame, high
Widely used for measuring the temperature of gases and members reaching the temperature.
Can be The size and shape of the thermistor
Is appropriately selected according to the conditions. A thermistor using the thermistor composition of the present invention
The production of the star is performed, for example, as follows. Get the final product
Filling into a cylindrical mold of desired dimensions during the above pressure molding
In the raw material powder thus obtained, two platinum wires of the desired size were placed on each wire.
With one end facing the line section and leaving the desired gap,
With the other end of each wire out of the mold
After placing, press molding. Next, the molded body is fired.
In this way, a support with two platinum wires as lead wires
-Mistor composition is formed. Also, the above two platinum wires
Is not placed at the time of the above-mentioned press molding, and pressurizes the above-mentioned raw material powder.
After firing the molded body, the fired body is whitened with an ion coater or the like.
A gold electrode is provided, and two platinum wires are wound around the platinum electrode.
Is also good. Temperature measurement of the thermistor thus obtained
Exposure to the environment to be measured and measure the resistance between the two leads.
From this resistance value, the conversion formula or conversion
Determining the temperature of the environment by using a circuit
Can be. [0017] EXAMPLES The following examples (including comparative examples) show the present invention.
The light will be described in more detail.Examples 1 to 6 and Comparative Examples 1 to 7 [
Examination of the effects of Commercial raw material Y_TwoO_Three, CaO, Cr_TwoO_Three, V_TwoO_Three,
Fe_TwoO_ThreeTable 1
[The ratio of the elements in the table (atomic%) is the total amount of the elements in the table.
Is 100 atomic%. Table 2 below
It is the same even if it is. Weighed so that each composition shown in
Then, this is mixed and pulverized by a ball mill, and then dried.
It was calcined at 200 ° C. This is crushed again with a ball mill,
Dried. The required amount of the obtained powder is 40 mmφ × 8 m
m at a temperature of 1600 ° C. in air.
After firing for a time, a sintered body was obtained. After that, the sintered body was
Cut into a 2mm x 20mm rectangular parallelepiped
Is provided with a platinum electrode, and a platinum wire is wound around the platinum electrode.
And a thermistor was formed. In addition,
When the powder X-ray diffraction was performed on the sintered body,
In the body, complex oxides of the elements shown in Table 1 are formed, and
Confirm that it has a lobskite-type crystal structure.
It has been certified. The sintered bodies of Examples 2 and 5 in Table 1
FIG. 1 (Example 2) and FIG.
2 (Example 5). JCPDS numbers in FIGS. 1 and 2
Is JCPDS-ICDD (Joint Committee on Powder)
 Diffraction Standard International Central for Di
ffraction Date) (also for FIGS. 3 and 4)
The same is true). The peaks marked with a triangle in FIG.
Complex oxides with a lobskite-type crystal structure (YCrO_Three)But
Exists and also has a peak marked with a circle,
Type oxide (YVO)_Four) May exist
I understand. In addition, in FIG.
Complex oxides with skyte type crystal structure (YCrO_Three)exist
You can see. Table 1 below shows the thermistors.
As shown in the table, the B value and the resistivity were determined. In Table 1, the formula
The value of (I) was varied in the range of 0.3 to 0.7. What
The value of equation (II) is 0.02, and the value of equation (III) is
Each was fixed at 0.5. [0019] [Table 1] The symbols in Table 1 represent the following meanings.¹⁾ : Cr / (Cr + M) = Cr / [Cr + (V, F
e))²⁾ : Q / (A + Q) = Ca / Y + Ca³⁾ : (A + Q) / (A + Q + M + Cr) = Y + Ca / Y
+ Ca + Cr + (V, Fe)^a) : Rate of change [%] = ｛B value in medium temperature range [K] −B in high temperature range
Value [K]｝ / B value in middle temperature range [K] × 100^b) : Thermi disclosed in JP-A-7-201528
Example of ceramic composition for star [Y: Sr: Cr: Fe: Ti
= 49.5: 0.5: 38.0: 9.5: 2.5 [atomic ratio%]] In Table 1, Examples 1 to 3 and Comparative Examples 1 and 2
It is a Y-Ca-Cr-VO-based sintered body, and Examples 4 to 6
And Comparative Examples 3 and 4 are Y-Ca-Cr-Fe-O-based sintered bodies
It is. As is clear from Table 1, Y-Ca-Cr-V-
For both O-based sintered bodies and Y-Ca-Cr-Fe-O-based sintered bodies,
The value of the formula (I) is out of the numerical range represented by the formula (I) '.
Then (Comparative Examples 1 to 4), the change rate of the B value increases.
I understand. In Comparative Examples 5 and 7, the change rate of the B value is large.
In Comparative Example 6, the rate of change of the B value was small.
Is too large (over 8000K)
Temperature can be measured over a wide temperature range.
Unsuitable as a high thermistor composition. [0021]Examples 7 and 8 and Comparative Examples 8 to 11 [Formula (I
Examination of the effects of fluctuations in the value of I)]: Commercial raw material Y_TwoO_Three, CaO, Cr_TwoO_Three, V_TwoO_Three,
Fe_TwoO_ThreeTable 2 below
Was weighed so as to have the composition shown in Examples 1 to 6 and Comparative Examples
In the same manner as described in Examples 1 to 7,
-Mista). For the obtained sintered body, powder X-ray
As a result of folding, all the sintered bodies had the elements shown in Table 2
A complex oxide is formed and a perovskite crystal structure
It was confirmed that it had a structure. Comparison in Table 2
X-ray powder diffraction of the sintered bodies of Example 8 and Comparative Example 10
3 (Comparative Example 8) and FIG. 4 (Comparative Example 10)
You. The presence of the peak marked with “▽” in FIG.
Complex oxide with a crystal structure (YCrO)_Three) Exists,
In addition, the presence of a peak marked with a circle indicates that
Composite oxide (YVO_Four) Is found to exist.
In addition, the presence of a peak marked with a circle in FIG.
Complex oxide with a crystal structure (YCrO)_Three) Exists
I understand. Thus, comparing FIG. 1 with FIG.
By comparing FIG. 2 with FIG.
In Examples and Comparative Examples, the composite contained in the thermistor composition
Although there is no difference in the crystal structure of the oxide, a certain amount of C
a thermistor over a wide temperature range
It can be seen that the change in the constant becomes very small. Each of the above services
As shown in Table 2 below, B value and resistivity
I asked. In Table 2, the value of equation (II) is set in the range of 0 to 0.04.
And fluctuated. Note that the value of the formula (I) is 0.5,
The value of equation (III) was fixed at 0.5. [0023] [Table 2] Code in Table 2¹⁾,²⁾,³⁾as well as^a)Is defined in Table 1.
Represents the same meaning as given. In Table 2, Example 7 and Comparative Examples 8 and 9 show Y-
It is a Ca—Cr—V—O based sintered body, and was compared with Example 8
Examples 10 and 11 are Y-Ca-Cr-Fe-O-based sintered bodies.
You. As is clear from Table 2, Y-Ca-Cr-VO system
Both the sintered body and the Y-Ca-Cr-Fe-O-based sintered body have the formula
The value of (II) is out of the numerical range represented by the formula (II) '
And whether the change rate of the B value is large (Comparative Examples 8, 9, 1)
0) or the change rate of the B value is small as in Comparative Example 11.
However, B value is too small (less than 3000K)
With this, temperature measurement is possible in a wide temperature range, and temperature measurement
It is not suitable as a highly accurate thermistor composition. [0025] As described above, the thermistor composition of the present invention
Due to its structure, it is wider than conventional thermistor compositions.
Thermistor constant is constant over a wide temperature range.
The following characteristics are obtained when the thermistor is manufactured using: Thermistor constant is 3000-8000 [K] The linearity of the thermistor characteristic is 200 to 1000 [K].
Good in the temperature range Stable at high temperatures Can easily be obtained. It
Therefore, when this composition is used as a thermistor,
Temperature range, and more accurate at high temperatures
Temperature measurement became possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 Powder X of the thermistor composition of Example 2 of the present invention
FIG. 3 is a diagram showing a line diffraction result. FIG. 2 shows a powder X of the thermistor composition of Example 5 of the present invention.
FIG. 3 is a diagram showing a line diffraction result. FIG. 3 is a diagram showing a powder X-ray diffraction result of the thermistor composition of Comparative Example 8. FIG. 4 is a diagram showing a powder X-ray diffraction result of the thermistor composition of Comparative Example 10.

Claims (1)

(57) [Claims 1] At least one of yttrium (Y) and a rare earth element (referred to as A), magnesium (Mg), calcium (Ca), strontium (S)
r), at least one element of barium (Ba) (referred to as Q), at least one element of vanadium (V) and iron (Fe) (referred to as M), and chromium (C
r) a thermistor composition composed of a substance having a perovskite-type crystal structure, which is a composite oxide of four elements, and an atomic ratio of Cr to the total of Cr and the element M; the following formula (I): Cr / (Cr + M) (I) is in a numerical range represented by the following formula (I) ′: 0.35 ≦ Cr / (Cr + M) ≦ 0.65 (I) ′, and the element Q with respect to the sum of the element A and the element Q The following formula (II): Q / (A + Q) (II) is within the numerical range represented by the following formula (II) ′: 0 <Q / (A + Q) <0.04 (II) ′ Element A with respect to the sum of A, Q, M and Cr
The following formula (III): (A + Q) / (A + Q + M + Cr) (III) is the following formula (III) ': 0.4 ≦ (A + Q) / (A + Q + M + Cr) ≦ 0.6 ( III) Thermistor composition characterized by being within the numerical range represented by '.