JPH03215356A - 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 MnO2, silica and 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 >=0.003 and <0.03mol% Mn (expressed in terms of MnO2) and >=0.01 and <0.5mol% 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 Field of Industrial Application] The present invention relates to barium titanate-based semiconductor porcelain, which has a positive resistance-temperature characteristic in which the electrical resistance value changes rapidly when the temperature exceeds a certain temperature. This invention relates to a barium titanate-based semiconductor ceramic composition that can reduce specific resistance at room temperature while ensuring voltage, and is useful as a low tumor anti-circuit element. [Prior art] Generally, barium titanate-based semiconductor porcelain contains barium titanate as a main component and Y, La, C as a semiconducting agent.
rare earth elements such as e, 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. It is used as a current limiting element, temperature control element, etc. Also, what is the Curie point of the barium titanate-based semiconductor porcelain mentioned above for its main component, barium titanate? The temperature is usually around 120℃ due to the sound. In order to shift this Curie point to the high temperature side, a method is known in which a part of Ba is replaced with Pb. Conversely, methods are also known in which a portion of Ba is replaced with Sr or a portion of Tl is replaced with Zr, Sn, etc. in order to shift the Curie point to the lower temperature side. It also contains a trace amount of manganese (0.03 to 0.00 in terms of Mn).
15s+oj! %) is known to significantly increase the rate of resistance temperature change after exceeding the Curie point. Furthermore, a trace amount (0.5~
It is also known that by adding 5mof%), 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.
Ox-added products have 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 by simultaneously replacing a part of Ba with Pb and Sr t Ca and incorporating these Pb, Sr, and Ca in a coexisting state in the main component barium titanate, It is stated that a withstand voltage of IOOV/■ or more can be obtained. [Problems to be Solved by the Invention] However, in the above-mentioned conventional barium titanate-based semiconductor porcelain, in which a part of the Ba mentioned above is replaced with Ca or Sr, although a satisfactory value of resistivity can be obtained, The highest voltage withstand voltage is only 48V/m, which is not a sufficient value for practical use. Further, as in the above publication, a part of Ba may be replaced with Pb. When Sr and Ca are substituted at the same time, a high withstand voltage can be obtained, but the specific resistance can only be lowered to 35Ω·1. Therefore, specific resistance 10Ω・1
There is a demand for the emergence of barium titanate-based semiconductor porcelain that can satisfy both the dielectric strength requirements of 100 V and above. 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. c.Means for Solving Problems] The inventors of the present invention have conducted extensive research to achieve the above object, and have found that BaTIOs. CaTiOs, SrT
iOs. The present invention was made based on the discovery that by using PbTl03 as the main component, selecting the subcomponents to be added to the main component, and limiting the amount added, it is possible to satisfy both the specific resistance and withstand voltage characteristics. Therefore, the present invention provides a main component consisting of barium titanate or a solid solution thereof, and a semiconducting agent. manganese. and a barium titanate-based semiconductor ceramic composition containing silica, wherein the main component is B a T i 0
．． 30-95 soj%, c a Ti
O s 3 ~ 25 mol %, S r
TiOs 1”-25mol%,
P b T I O s 1 to 30 oJ%, and the main component contains a rare earth element such as Y, La, Co, etc. or Nb. Bi. Sb. W. At least one type of oxide of Th is 0.05 mol% or more Q,j
moj% and manganese is added less than MnO. Converting to 0.003 sol% or more and less than 0.03 aoj%,
Silica converted to 3101 Li'0.01 moj% or more 0
．． It is characterized in that it contains less than 5 mail% of each. Here, the reasons for limiting various conditions in the present invention will be explained. ■ Above BaTiOs, CaTiOs, SrTi
Os. The main component was P bT i Os.
This is to improve the withstand voltage value by replacing a part of this Ba with Ca, Sr, and Pb at the same time. The above Pb
, Sr alone have their Curie points on the high temperature side. These Ca, Sr. By containing Pb in the coexisting state as a main component, the withstand voltage of 10
Achieves 0V/wa or more. ■ The reason for limiting the range of each principal component above is as follows. The reason why the above B a Ti O s is set to 30 to 95 moj% is that if it is less than 30 moj%, it becomes difficult to convert it into a semiconductor and the specific resistance increases, but if it exceeds 95-o 1%, the electrical characteristics will deteriorate significantly. Because it does. In addition, the above C a Ti O s is added to 3 to 25 mo J
% because if it is less than amol%, the effect of its inclusion will not be obtained, and if it exceeds 25moJ%, the withstand voltage properties will be poor. This is because it results in a decrease in inrush current characteristics. Furthermore, the above SrTiO is set at 1 to 25 mo II% because if it is less than 1 mol %, the effect of improving the properties is small, and if it exceeds 25*o II%, the electrical properties deteriorate. Furthermore, 1 to 30 mo 14% of the above PbTi03
This is because if it is less than lmoj%, the effect of improving characteristics is small and it is not suitable for practical use, and if it exceeds 30moj%, it becomes difficult to make it into a semiconductor. ■ Furthermore, it is known that the above-mentioned semiconducting agent is added to obtain barium titanate-based semiconductor ceramics, and the amount added is in the range of 0.05 mol% or more and less than 0.21101% to lower the specific resistance. The above is optimal. ■Furthermore, by adding the above-mentioned manganese, it is possible to significantly increase the rate of change of the positive resistance temperature characteristic beyond the Curie point. The amount of manganese added is MnO. The reason for setting the amount to be 0.003 moj% or more and less than 0.03 moj% in terms of 0.003 moj% or more is because when the amount added is 0.03 mol% or more, the resistivity at room temperature becomes high, and 0.003 moj% or more
This is because if the amount is less than %, the effect of addition cannot be obtained, and the withstand voltage characteristics will deteriorate on the contrary. ■ Furthermore, the above silica is SiO! Convert to 0.01mo 1% or more 0.5s
The reason why it is set to less than 0.0j% 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 it is outside the above range, the above effect will be lost. This is because you will not be able to obtain it. Here, the above-mentioned semiconducting agent. The amount of manganese and silica added was limited to facilitate lowering the specific resistance while ensuring the necessary withstand voltage.If even one of the above is out of range, firing, etc. to lower the resistance may be required. Condition setting may be difficult. [Function] According to the barium titanate-based semiconductor ceramic composition according to the present invention, as described above, BaTiO. , CaTies *
SrTiOs. Since PbTiOs is the main component,
In other words, since a part of this Ba is replaced with Ca, Sr, and PB at the same time, the withstand voltage can be improved.Furthermore, the semiconducting agent added to the above main component is 0.05■oj% or more and less than 0.2soJ%, and manganese Convert to Mn08 and get 0.003
moj% or more but less than 0.03moj%, silica Slo
Since it is 0.01 mol% or more and less than 0.51104% in terms of g, it is possible to reduce the specific resistance while ensuring the necessary withstand voltage, resulting in a withstand voltage of 100 V/■ or more and a specific resistance of 10
It is possible to realize a low-resistance circuit element of Ω・1 or less, meeting the above-mentioned requirements. [Examples] Examples of the present invention will be described below. This example describes an experiment in which the amounts of each main component and each subcomponent added in the present invention were determined. First, we will explain the method for manufacturing the samples used in the experiment. B a Ti O s (60 to 90 mo
j%). Ca TiOs (0~30moj
%), SrTiOs (0-12 mol%), P
b T i Os (0-13 moj%), Yt Os (0.1-1.5 mol%) as a semiconducting agent.
La wealth Os (0.15so j%),
C e Ox (0.15 go 1%) .Ndg
Os (0.15mo J%), and M as an additive
n CO s (converted to M n O *0.
01-0.15moj%). SiO! (0.1
~1. Prepare O vlol%). 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 at 1150°C.
× Temporary firing for 2 hours. Next, this pre-sintered body is pulverized and mixed, a binder is added thereto, granulated, and a molding pressure of 100
Press into a disc shape at 0 kg/cd. Next, this disc-shaped compact was heated to 1360°C at 10°C/in, held for a predetermined time, and then fired using a firing profile in which it was cooled at 10°C/s+in. This makes the diameter 17.5X
Obtain a disc-shaped semiconductor porcelain with a thickness of 0.6. 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, we investigated the specific resistance and withstand voltage of each sample at room temperature (25°C). The Curie points of each 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. The compounding ratios of the semiconducting agent and additives are shown, and Table 2 shows the results of each measurement. In the table, samples Asahi 7-9, Pkl 1-13, P&L16. and 18 to 20 are within the scope of the present invention, and other *
Marks are outside the scope of this invention. As is clear from the table, when the amount of each main component added is outside the specified range (-1 to 6), the withstand voltage is 45%.
Low, below V/fi. Also, semiconducting agents, SiO1, Mn
Ot. When the addition amount of CaTiOs and CaTiOs exceeds the specified range (llhlO.Nal 4.15, Nal 7
), the resistivity increased significantly or fused during firing, and the resistivity of all samples increased. 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 (1117 to 9, l1h
ll-13, Chen 16, -18 to 20) have a Curie point of 103 to 122°C and a specific resistance of 3.2 to 4.9Ω.
-1, and the withstand voltage is high at 104 to 152 V/W, indicating that a satisfactory value has been obtained. [Effects of the Invention] As described above, according to the barium titanate-based semiconductor ceramic composition of the present invention, B a T i Os 3G to 95
soil%. CaTiOs 3-25 mo/%. SrT
iOs1-25soJ%, P b T i Os
1 to 301101% as the main component, to which 0.05 mo j% or more of a semiconductor forming agent and 0.2 whole % ungrooved are added, and 0 in terms of Mn jcM n O *
．． 003 soj! % or more and less than 0.03 mol%, Si
Ox O. 01moj% or more and less than 0.5moj%, respectively, so the withstand voltage is 100V/M or more,
It has the effect of providing excellent characteristics with a resistivity of 10Ω·1 or less, and of producing semiconductor porcelain useful as a low-resistance circuit element.

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%, and manganese is 0.003 mol% or more in terms of MnO_2.
Less than 0.03 mol%, silica is 0.03% in terms of SiO_2.
A barium titanate-based semiconductor ceramic composition, characterized in that the barium titanate-based semiconductor ceramic composition contains 0.01 mol% or more and less than 0.5 mol%.