JPH05339052A - Dielectric ceramic composition for temperature compensation - Google Patents

Abstract

PURPOSE:To obtain a dielectric ceramic composition having excellent Q value, high dielectric constant and small thermal coefft. of dielectric const. by specifying the ranges of main components BaO, BiO3/2 and ReO3/2 in the ternary phase diagram, specifying the proportion of TiO2, and further constituting ReO3/2 of Nd, La and Pr with a specified proportion. CONSTITUTION:This dielectric ceramic compsn. is expressed by general formula (x.BaO-y.BiO3/2-z.ReO3/2)-c.TiO2, wherein Re represents rare earth elements and x y and z satisfy x+y+z=100. The proportion of these components by mol amt. is shown in the ternary phase diagram, and its range is in the area (including the boundary) defined by lines connecting the compsn. points A, B, C, D, E, and F. The mol amt. c of TiO2 is 110-140 to the value in parentheses of the general formula. ReO3/2 consists of d.Nd-e.La-f.Pr, wherein d+e+f=z. If z=100, z=d'+e'+f' and d'=20 to 90, e'=10 to 80 and f'=0 to 30. the source materials are compounded in this range, calcined, compacted, and sintered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition for temperature compensation, which has an excellent Q value, a small coefficient of change in dielectric constant with temperature, and a high dielectric constant.

[0002]

_2. Description of the Related Art Conventionally, BaO--TiO ₂ --Re ₂ O _{3 has been used.}
A composition composed of a system (Re represents a rare earth element) is known as a dielectric ceramic composition for temperature compensation, which has an excellent Q value, a small coefficient of change in dielectric constant with temperature, and a high dielectric constant.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The dielectric ceramic composition for temperature compensation of the iO ₂ —Re ₂ O ₃ system is
The dielectric constant is 90 or less, the temperature coefficient is -20 ppm / ° C, and the Q value is about 4000. The electrical characteristics of these are further miniaturization of single-layer capacitors such as disk capacitors and cylindrical capacitors. However, there is a problem that it is not a satisfactory value when used as capacity expansion.

An object of the present invention is to solve the above problems and to provide a temperature-compensating dielectric porcelain composition having Q-value and dielectric constant temperature characteristics satisfying as a temperature-compensating capacitor.

[0005]

The temperature-compensating dielectric ceramic composition of the present invention has the general formula (x.BaO-y.BiO3 / 2-z.ReO3 / 2) -c.
- consists TiO _2, Re represents a rare earth element, x + y + z = 10
A composition having a composition of 0, the proportions of these components being the following composition points A, B, C, D, E, Fx.BaOy.BiO3 / 2z.ReO3 / 2 in the ternary system diagram. A 35 30 35 B 30 30 40 C 25 35 40 D 20 35 45 E 20 30 50 F 35 35 50 is the molar amount on the line connecting and within the composition range surrounded by this line, and the value c of TiO ₂ is (X ・ BaO-y ・ B
iO 3 / 2-z · ReO 3/2) is in the range of 110 to 140, and ReO 3/2 is d · Nd−e · La−.
f · Pr, and d + e + f = z, and z
= 100, it has a composition of z = d '+ e' + f ', and further d' = 20 to 90, e '= 10 to 80, f' =
It is characterized in that it is in the range of 0 to 30.

[0006]

[Function] The main component of the dielectric ceramic composition for temperature compensation is x.
The composition of BaO · yBiO 3/2 · zReO 3/2 is x + y +
The reason why z = 100 and the proportion of these components is the molar amount on the line connecting the composition points A, B, C, D, E, and F in the ternary system diagram and within the composition range surrounded by this line is as follows.
In the region L shown in FIG. 1, there is no significant difference in the dielectric constant as compared with the conventional dielectric ceramic composition for temperature compensation, and in the region M
, The sinterability becomes extremely difficult and the feasibility decreases,
Further, in the region N, values satisfying the dielectric constant and the temperature coefficient cannot be obtained.

In addition, the value of c of TiO ₂ is (x.BaO-
y · BiO 3 / 2-z · ReO 3/2) 110-1
The reason for setting the range of 40 is that when the c value is less than 110, the sinterability is significantly deteriorated and the Q value is lowered, and when the c value exceeds 140, the dielectric constant is decreased and the temperature coefficient is increased. Is increased to the negative side.

Further, the composition of Re (rare earth element) is within the range of molar amount of the main component, and d + e + f = z, and z =
When it is 100, it has a composition of z = d '+ e' + f ',
Furthermore, d '= 20-90, e' = 10-80, f '= 0-
The reason for setting the range to 30 is that when the composition of the rare earth element is selected within the above composition range, the dielectric constant, temperature coefficient and Q value are improved.

That is, when d '= Nd is less than 20, a value satisfying the temperature coefficient cannot be obtained, and e' = La.
When is less than 10, the temperature coefficient is improved, but a value that satisfies the permittivity cannot be obtained, and when f ′ = Pr exceeds 30, values that satisfy both the permittivity and the temperature coefficient are not obtained. This is because the sinterability is poor and it is not practical. The reason for selecting the rare earth elements as La, Nd and Pr is as follows.
This is because it is cheap to be used industrially and can be manufactured into a product with low production cost.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the attached drawings will be described. FIG. 1 is a ternary system diagram showing the composition range of the main components of the temperature-compensating dielectric ceramic composition of the present invention. The composition points A, B, C, D, E, F
The region surrounded by (thick line) is the composition range of the main component of the composition of the present invention, and the numbers plotted in FIG. 1 are shown in Table 1 below.
The sample number of is shown.

Next, specific examples of the present invention will be described together with comparative examples. Experimental Example First, as a starting material, high-purity barium carbonate (BaC) was used.
o ₃ ), bismuth oxide (Bi ₂ O ₃ ), titanium oxide (Ti
O ₂ ), lanthanum oxide (La ₂ O ₃ ), praseodymium oxide (Pr ₂ O ₃ ) and neodymium oxide (Nd ₂ O ₃ ) powders were prepared. Next, each raw material is shown in Table 1 (sample numbers 1-27), Table 2 (sample numbers 28-55), and Table 3 (sample numbers 56-8).
3) and weighed so as to obtain the amounts shown in Table 4 (Sample Nos. 84 to 99).

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

Those marked with * in Tables 1, 2, 3, and 4 are compositions within the scope of the present invention, and other compositions are outside the scope of the present invention. In addition, the numbers (6, 9, 14, 23) given in the same positions as * in Tables 2, 3 and 4 are the same as the sample numbers in Table 1, and are shown for comparison with other samples. Described. Then, each raw material blended as shown in Table 1, Table 2, Table 3, and Table 4 was put into a ball mill whose inner wall was resin-coated with zirconia balls and pure water, and after wet mixing for several hours, dehydration was performed. It was dried and dry-milled to obtain a powder mixture. This powder mixture was put in a porcelain sheath and calcined in an oxidizing atmosphere at a temperature in the range of 1100 ° C. to 1200 ° C. for 2 hours according to the composition of the powder mixture to prepare a sintered body. The produced sintered body was again dry-ground in a mortar and then wet-ground in the ball mill to obtain a fine powder. Polyvinyl alcohol was added as an organic binder to this fine powder, and the mixture was granulated and then press-molded using a dry molding machine at a pressure of ² t / cm ² , to obtain a diameter of 10 mm,
A disk-shaped molded product having a thickness of 0.5 mm was prepared.

The formed product is placed in an alumina sheath, and the temperature is adjusted to 130 according to the composition of the product in an oxidizing atmosphere.
A disc-shaped temperature compensating dielectric porcelain composition was prepared by sintering at 0 ° C to 1350 ° C for 2 hours. Each of the disk-shaped temperature compensating dielectric ceramic compositions was baked with silver electrodes having a certain area on both sides, and each temperature compensating dielectric ceramic composition was measured by an impedance analyzer (model 4192A) manufactured by YHP. The capacitance, Q value, and temperature characteristics of capacitance were measured. Further, the relative permittivity (see the following formula) was determined from the shape of each temperature-compensating dielectric ceramic composition and the electrode area. The measurement conditions with the impedance analyzer were a measurement frequency of 1 MHz and a signal voltage of 1V. Further, the temperature coefficient (see the following formula) was determined from the capacitance value measured at temperatures of 20 ° C and 85 ° C.

Specific permittivity ε = (4 / ε ₀ / π) × C20 × t / D ² Temperature coefficient Tc = (C85−C20) / C20 / 65 × 1
0 ^{6 where} ε _{0 is} the dielectric constant in vacuum, π is the circular constant, t is the thickness (mm) of the sintered body, and D is the electrode area (m.
m ² ), C20: 20 ° C. capacitance (pF), and C85: 85 ° C capacitance (pF).

The obtained results are shown in Table 5, Table 6, Table 7, and Table 8 corresponding to the sample numbers in Table 1, Table 2, Table 3, and Table 4, respectively.

[0020]

[Table 5]

[0021]

[Table 6]

[0022]

[Table 7]

[0023]

[Table 8]

Those marked with * in Tables 5, 6, 7, and 8 are compositions within the scope of the present invention, and other compositions are outside the scope of the present invention. In addition, the numbers (6, 9, 14, 23) given in the same positions as * in Tables 6, 7, and 8 are the same as the sample numbers in Table 5, and for comparison with other samples. Described. Further, in the columns of temperature coefficient Tc in Tables 5 and 6, for which no data is described, the samples which could not be measured because the change in capacitance with temperature was not linear. As is clear from Tables 5, 6, 7, and 8, the temperature-compensating dielectric ceramic composition within the composition range of the present invention (indicated by * in Tables 1 to 8) is satisfactory as a temperature-compensating capacitor. It can be seen that it has temperature characteristics of Q value and permittivity. On the other hand, compositions outside the composition range of the present invention, for example, sample numbers 1, 2, 11, 16, 2 in the above table
Nos. 4, 26, etc. are not suitable for practical use because they have a small Q value, dielectric constant, or temperature coefficient, or have poor sinterability and poor reproducibility.

[0025]

As described above, according to the present invention, the Q value,
Since the temperature characteristic of the dielectric constant has a value satisfying as a temperature compensating capacitor, and the dielectric constant is larger than that of a conventional temperature compensating dielectric porcelain composition, product miniaturization,
It has the effect of providing a temperature-compensating dielectric porcelain composition capable of increasing the capacity.

[Brief description of drawings]

FIG. 1 is a ternary system diagram showing a composition range of main components of a temperature-compensating dielectric ceramic composition of the present invention, showing composition points A, B,
The region surrounded by C, D, E and F shows the composition range of the main component of the composition of the present invention.

Claims (1)

[Claims] 1. The general formula (x.BaO-y.BiO3 / 2-z.ReO3 / 2) -c.
- consists TiO _2, Re represents a rare earth element, x + y + z = 10
A composition having a composition of 0, the proportions of these components being the following composition points A, B, C, D, E, Fx.BaOy.BiO3 / 2z.ReO3 / 2 in the ternary system diagram. A 35 30 35 B 30 30 40 C 25 35 40 D 20 35 45 E 20 30 50 F 35 35 50 is the molar amount on the line connecting and within the composition range surrounded by this line, and the value c of TiO ₂ is (X ・ BaO-y ・ B
iO 3 / 2-z · ReO 3/2) is in the range of 110 to 140, and ReO 3/2 is d · Nd−e · La−.
f · Pr, and d + e + f = z, and z
= 100, it has a composition of z = d '+ e' + f ', and further d' = 20 to 90, e '= 10 to 80, f' =
A dielectric porcelain composition for temperature compensation, which is in the range of 0 to 30.