JPH03215355A - Barium titanate-based semiconductor ceramic composition - Google Patents

Abstract

PURPOSE:To provide the title composition having high dielectric strength and small resistivity by simultaneously replacing a part of Ba with Ca, Sr and Pb and specifying the amount of semiconducting agent to be added. CONSTITUTION:The objective composition consisting essentially of 30-95mol% BaTiO3, 3-25mol% CaTi, 1-25mol% SrTiO3 and 1-30mol% PbTiO3 and containing >=0.05 and <0.2mol% one or more kinds of rare earth elements such as Y, La and Ce or oxide of Nb, Bi, Sb, W and Th as semiconducting agent and containing 0.03-0.1mol% Mn (expressed in terms of MnO2) and 0.5-5mol% silica (expressed in terms of SiO2). The composition has excellent characteristics of >=100V/mm dielectric strength and <=10OMEGA.cm resistivity.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to barium titanate-based semiconductor porcelain, which has positive resistance-temperature characteristics in which the electrical resistance value changes rapidly when a certain temperature is exceeded. It relates to a barium titanate-based semiconductor porcelain composition that can reduce specific resistance at room temperature while ensuring voltage, and is useful as a low-resistance circuit element. [Prior Art] In general, barium titanate-based semiconductor porcelain contains Y, La, and C are added to barium titanate as semiconducting agents.
Rare earth elements such as o. Or Nb, Bi, Sb. W,T
It is obtained by adding a trace amount of at least one of h, etc. and firing it at a high temperature. This semiconductor porcelain has a characteristic that it has a low specific resistance at room temperature and exhibits a significant positive temperature change in resistance when it exceeds the Curie point, and can be used, for example, as a constant temperature heating element. Current limiting element. It is used as a temperature control element, etc. Furthermore, the Chierie point of the barium titanate-based semiconductor porcelain is usually around 120°C due to the influence of its main component, barium titanate. A method is known in which part of Ba is replaced with Pb in order to shift this Chierly point to the high temperature side. On the contrary, in order to shift the Chierly point to the low temperature side, a part of Ba is replaced with Sr, a part of Ti is replaced with Zr. A method of substituting with Sn or the like is also known. In addition, a trace amount of manganese (0.03 to 0.1 in terms of Mn)
It is also known that the addition of Ni (5■oj%) significantly increases the rate of change in resistance temperature after exceeding the Chierie point. Furthermore, the amount of sin (0.5 to 5 so
It is also known that by adding Z%), the specific resistance at room temperature can be made low and stable. Here, the barium titanate-based semiconductor porcelain is required to have a high withstand voltage and a low specific resistance at room temperature, making it useful as a low-resistance circuit element. Conventionally,
In order to improve such resistivity characteristics, a part of Ba is replaced with Ca or Sr, and Mn, Si and Sr are added as additives.
A product containing Ot has been proposed. According to this, a characteristic with a specific resistance of 10Ω·1 or less at room temperature can be obtained.
In addition, Japanese Patent Publication No. 63-28324 discloses that a part of Ba is converted into pb, Sr. Simultaneously substituted with Ca, these Pb, Sr
, it is stated that a withstand voltage of IOOV/■ or more can be obtained by including Ca in the coexisting state in barium titanate, which is the main component. [Problems to be Solved by the Invention] However, in the above-mentioned conventional barium titanate-based semiconductor porcelain, in which a part of the above-mentioned 13a is replaced with Ca or Sr, although a satisfactory value of resistivity can be obtained, The highest voltage withstand voltage is only 48V/■, which is not a sufficient value for practical use. Further, as in the above publication, a part of Ba may be replaced with Pb. Those substituted with Sr and Ca at the same time are
Although high withstand voltage can be obtained, the specific resistance is 35Ω
・Can only be lowered to B. Therefore, the specific resistance 1
Less than 0Ω・Ro. There is a demand for the emergence of barium titanate-based semiconductor ceramics that can satisfy both of the requirements of a withstand voltage of 100 V/■ or more. An object of the present invention is to provide a barium titanate-based semiconductor ceramic composition that has high withstand voltage and low specific resistance. [Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention conducted intensive research and found that BaTiOs. CaTiOs. SrT
iOs. PbTiOs is the main component, and by selecting the subcomponents added to it and limiting the amount added, the specific resistance can be increased. We have discovered that both characteristics of withstand voltage can be satisfied, and have completed the present invention. Therefore, the present invention provides a main component consisting of barium titanate or a solid solution thereof, and a semiconducting agent. In a barium titanate-based semiconductor ceramic composition containing manganese and silica, the main component is B a T i O
@30~95mo J LAGS C a T
iOs3~2Smo1%, S
r T i O @ 1 ~ 25so4 %,
P b T t O s 1 to 30 mo J%, with Y, La, Co as a semiconducting agent in the main component.
Rare earth elements such as Nb. B t, Sb, W, Th
0.05 mol% or more and less than 0.2 s+oj% of at least one of the oxides of
, converted to 0.03~0. Imol%, silica is S
It is characterized by the addition content of 0.5 to 51107% in terms of iOt. Here, the reasons for limiting various conditions in the present invention will be explained. ■ Above BaTiO,,CaTiO,,SrTi0s
, PbTi 02 as the main component is that a part of this Ba is Ca. This is to improve the withstand voltage value by replacing with Sr and Pb at the same time. When used alone, Pb and Sr shift the Curie point toward high and low temperatures, respectively, but by including Ca, Sr, and Pb in coexistence as the main components, the withstand voltage can be increased to 100 V/m.
The above can be achieved. ■ The reason for limiting the range of each generated component above is as follows. The above BaTiO* was filled with 30 to 95 soJ%.
This is because if it is less than 0 sol %, it will be difficult to make it into a semiconductor and the specific resistance will increase, and if it exceeds 95 mol %, the electrical characteristics will be significantly degraded. In addition, the above C a T I O s is added to 3 to 25 mo
The reason why it is set as 1% is that if it is less than Smol%, the effect of its inclusion will not be obtained, and if it exceeds 25■oJ%, the withstand voltage characteristics will deteriorate. This is because it results in a decrease in inrush current characteristics. Furthermore, 1 to 25 mol of the above SrTiOs
% because if it is less than 1 mol %, the effect of improving the characteristics will be small, and if it exceeds 25 wbo It %, the electrical characteristics will deteriorate. Furthermore, the reason why the above PbTiOs is set to 1 to 30II01% is because if it is less than 1 mol %, the effect of improving characteristics is small and it is not practical, and if it exceeds 30 mol %, it becomes difficult to make it into a semiconductor. ■Additionally, by adding the manganese mentioned above, the rate of change of the positive resistance temperature characteristic beyond the Curie point can be significantly increased. The amount of manganese added is converted to MnOg and is 0.03
The reason for setting it to ~0.1 mol% is that the amount added is 0.03
s+on! This is because if it is less than 0.1 moffi%, the addition effect will not be apparent and the withstand voltage characteristics will deteriorate, and if it exceeds 0.1 moffi%, the specific resistance at room temperature will increase. ■ Furthermore, the above silica is converted to SiO wealth from 0.5 to
The reason for setting Smo to 7% is to suppress changes in resistivity caused by slight fluctuations in the addition of a small amount of semiconducting agent and to suppress abnormal grain growth in the sintered body.If the Smo content is outside of the above range, the above effect will not be obtained. This is because you will no longer be able to do so. ■ The amount of the above semiconducting agent added should be 0.05 mol% or more.
．． The above-mentioned manganese. This is because it has been found that when the amount of silica added is limited, the resistivity increases when the amount of silica added is outside the above range. Therefore, the amount of the semiconducting agent added is 0.05-o.
j! % or more and less than 0.2% o154, it is possible to achieve a specific resistance of lOΩ・(self) or less. [Function] According to the barium titanate-based semiconductor ceramic composition according to the present invention, as described above, BaTiO, CaTies. S
rTiO. ．． PbTiO. Since Ba is used as the main component, that is, part of this Ba is replaced with Ca, Sr, and PB at the same time, so the withstand voltage can be improved.Furthermore, the semiconducting agent added to the main component is 0.05 oz or more. Since it is less than 2 mol%, the specific resistance can be reduced while ensuring the necessary withstand voltage, resulting in a withstand voltage of 100 V/m or more and a specific resistance of 10 Ω.
It is possible to realize a circuit element with a low resistance of 1 or less, and meet the above requirements. [Examples] Examples of the present invention will be described below. This example describes each product in the present invention. We will explain the experiment in which we found the amount of each subcomponent added. First, we will explain the method for manufacturing the samples used in the experiment. B a T i O 1 (60 to 90 mo
1%). Ca TiOs (0~30moj
%)． S r Ti Os (0-12 mol
%), PbTiOs (0 to 13 mol
! %), Yt'Os (0.1-1
．． 5 soj%>+1-atOx (0.15110
7%), C e Ox (0.15
sol%), N's 03(0.15mo
j%), and Mn CO s (M n
0.03 to 0.12 soIl% (converted to Ot).
Prepare S i Os (0.5 to 8.0 mo1%). These raw materials are blended and wet-mixed so as to obtain a barium titanate-based semiconductor ceramic composition having the ratio shown in Table 1. Next, the slurry-like raw material was dehydrated and dried to a size of 115"
Temporarily bake for 2 hours. Next, this pre-sintered body is pulverized and mixed, a binder is added thereto and granulated, and a molding pressure of 10
Press-form into a disc shape at 00 kg/1. Next, this disc cane molded body was heated to 1360°C at a rate of 10°C/win, held for a predetermined time, and then fired using a firing profile in which it was cooled at a rate of 10°C/in. As a result, a disk-shaped semiconductor porcelain with a diameter of 17.5w and a thickness of 0.6w is obtained. Then, electrodes made of In-Ga alloy were provided on both main surfaces of this semiconductor ceramic, and this was used as a sample for this experiment. In this experiment, the resistivity, withstand voltage, and Chierly point of each of the above samples at room temperature (25°C) were measured.
The above withstand voltage was measured at the maximum applied voltage value just before the sample was destroyed. Tables 1 and 2 show the results, and Table 1 shows the above main components and semiconductor forming agent. Table 2 shows the respective measurement results. In the table, samples Na7-9, ll&hll-13, Na16.
and Na18-20 are within the scope of the present invention, and other middle marks are outside the scope of the present invention. As is clear from the table, when the amount of each main component added is out of the specified range (Nal ~ 6), the withstand voltage is 6.
Low, less than 3v/■. Also, semiconductor chemistry, Slot, Mn
Ot. When the amount of addition of CaTiOz and CaTiOz exceeds the specified range (mlo.ml4.l5, Il&Ll?), the resistivity increases significantly or is fused, and in any sample, the resistivity, Satisfactory characteristics have not been obtained for both withstand voltage and voltage. On the other hand, when each addition amount is within the range of the present invention (Na7~9, I1h11~
l3, Arashi l6,! klB~20》 have a Chierie point of 102~120℃, a low specific resistance of 4.2~4.9Ω・Ro, and a high withstand voltage of 118~153V/w, which are satisfactory values. You can see that you are getting it.
[Effects of the Invention] As described above, according to the barium titanate-based semiconductor ceramic composition of the present invention, BaTiOs30-951104
%, C a Ti Os 3 ~ 25
so1%, SrTiOs1 ~25mo 1%
．． The main component is PbT i Os 1 to 30 mol%, and the semiconducting component is 0.05 mol% or more to 0.
．． While adding less than 2■oj%, Mn
0.03 to 0.1 ■oj% converted to Ot, Si
Since 0.5 to 51 ol% of Ox is added, excellent characteristics such as a withstand voltage of 100 V/fin or more and a specific resistance of 10Ω/1 or less can be obtained, and a semiconductor porcelain useful as a low resistance circuit element can be obtained. effective.

Claims (1)

[Claims] (1) A barium titanate-based semiconductor ceramic composition in which a semiconducting agent, manganese, and silica are added to the main component consisting of barium titanate or a solid solution thereof,
The above main components include 30 to 95 mol% of BaTiO_3;
CaTiO_3 is 3-25 mol%, SrTiO_3 is 1-25 mol%, PbTiO_3 is 1-30 mol%
Y, as a semiconducting agent for the above main component.
Rare earth elements such as La, Ce or Nb, Bi, Sb,
At least one of the oxides of W and Th is 0.05 mo
1% or more and less than 0.2 mol% added, and manganese is 0.03 to 0.1 mol% in terms of MnO_2,
A barium titanate semiconductor ceramic composition characterized in that silica is added in an amount of 0.5 to 5 mol% in terms of SiO_2.