JPH03215354A - 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 silica 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 0.2-1.0mol% 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 >=0.01 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 a certain temperature is exceeded. 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-resistance circuit element. [Prior Art] Generally, barium titanate-based semiconductor porcelain contains barium titanate as a main component and Y.I. as a semiconductor agent. La. C
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 Chierly point.For example, it can be used as a constant temperature heating element. It is used as a current limiting element, 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. 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. 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. It also contains a trace amount of manganese (0.03 to 0.00 in terms of Mn).
It is also known that adding 1510a%) significantly increases the rate of change in resistance with temperature after exceeding the Chierie point. Furthermore, a trace amount of SiO2 (0.5 to 5 mo
It is also known that the specific resistance at room temperature can be made low and stable by adding 1%). 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 and SiO are added as additives.
2 has been proposed. According to this, a characteristic with a specific resistance of 10Ω·1 or less at room temperature can be obtained. Furthermore, Japanese Patent Publication No. 63-28324 discloses that a part of Ba is simultaneously replaced with pb, Sr, and Ca, and these Pb. Sr,
It is stated that by impregnating barium titanate, the main component, with Ca in the coexistence state, 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/■, which is not a sufficient value for practical use. Furthermore, as in the above publication, a part of Ba is replaced with Pb, Sr, and Ca at the same time, and although a high withstand voltage can be obtained, the specific resistance can only be lowered to 35Ω. Therefore, the specific resistance is 10Ω
・Less than 1. 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. CaTi0 3 ,
S r T i O s , P b T i O
By setting s as the main component, selecting the subcomponents added to it, and limiting the amount added, the specific resistance can be achieved. 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
*30-95so J%, CaTiOs3
~25s+o,j %, S r T i O
s1~25mol%, pb"rtos1~
30 mo j%, and the main component contains at least one of rare earth elements such as Y + L a * C a or oxides of Nb, Bi, Sb, W, and Th as a semiconductor agent in an amount of 0.2 to 1. Omol% is added, and manganese is MnO. Converting to 0.03-0.1 mol%
, silica is added and contained in an amount of 0.01s+oj% or more and less than 0.5 sol%, respectively, in terms of Sin. Here, the reasons for limiting various conditions in the present invention will be explained. ■ The above BaTiOs. CaTiOs, SrTi
The reason why O s * P b T s O 3 is used as the main component 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 and Sr individually have their Chierie points on the high temperature side and
These Ca. Sr,
By including pb as the main component in a coexisting state, a withstand voltage of 100 V/vm or more can be achieved. ■ The reason for limiting the range of each principal component above is as follows. 30-95+mol% of the above 13 a TiOs
The reason for this is that if it is less than 30 mo j %, it will be difficult to make it into a semiconductor and the specific resistance will increase, and if it exceeds 95 so j %, the electrical characteristics will deteriorate significantly. In addition, the above CaTiO. The reason why O is set at 3 to 25 mo J% is that if the content is less than 3 @O j %, the effect of its inclusion cannot be obtained, and if it exceeds 25 mo 1%, the withstand voltage characteristics and inrush current characteristics will deteriorate. Furthermore, the above SrTiO. 1 to 25 soJ% is 1moJ! This is because if the amount is less than 25 ol%, the effect of improving the characteristics will be small, and if it exceeds 25 ol%, the electrical characteristics will deteriorate. Furthermore, the reason why the above-mentioned PbTiOs is set to 1 to 30 soj% is that if it is less than 1 oIl%, the effect of improving characteristics is small and it is not suitable for practical use, and if it exceeds 3 oJ%, it becomes difficult to make it into a semiconductor. It is from. ■ Also, it is known that the above-mentioned semiconducting ferns are added in order to obtain barium titanate-based semiconducting porcelain, and the amount of these additions is as follows:
0.2-1. The Omol% range is appropriate for lowering the specific resistance. ■Furthermore, by adding the manganese mentioned above, the rate of change of the positive resistance temperature characteristic beyond the Licurie point can be significantly increased. The reason why the amount of manganese added is 0.03 to 0.1 mol% in terms of MnOx is because if the amount added is less than 0.03 moJ%, the addition effect will not appear and the withstand voltage characteristics will deteriorate. This is because if it exceeds 0.1 mol%, the resistivity at room temperature will increase. ■ Also, convert the above silica into Slot and get 0. Olm
The reason why the content is set to 1% or more and less than 0.5*oj% is to suppress changes in resistivity caused by slight fluctuations in the addition of a small amount of semiconducting agent, and to ensure the necessary withstand voltage while reducing the resistivity value at room temperature. This is to do so. If the amount of silica added is 0.5 moJ% or more, low resistivity cannot be achieved due to the relationship with the Mn amount, and if it is less than 0.01 moJ%, the particles of the sintered body may become abnormal grains. It is from. [Function] According to the barium titanate-based semiconductor ceramic composition according to the present invention, as described above, BaTiOs, CaTies. S
rTiOs. Since PbTiOs was used as the main component, that is, part of this Ba was replaced with +Sr and pb at the same time, so the withstand voltage could be improved, and the silica added to the main component was 0.01 ol% in terms of SiO2. 0.5m or more
Since it is less than oJ%, it is possible to reduce the specific resistance while ensuring the necessary withstand voltage, resulting in a withstand voltage of 100 V/m or more,
It is possible to realize a low-resistance circuit element with a specific resistance of 10Ω·1 or less, meeting the above 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 Os (69-90 mol
%). Ca Ti Os (0~15soJ
%) , S r T i Os (0
~12 mol%) + P b T 10 s (0
~10moJ%), YmOs (
0.2-0.3 s+oj%), La. Os (0.
2moJ%). C e Ot(0.3
mob%), Nd. Ox (0.4 mol%),
and M n CO s (0.03 to 0.12 soJ% in terms of MnO), St08 (O to 6
．． 0-07%). 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/1. Next, this disc-shaped compact was heated to 1360°C at a rate of 10°C/sin, held for a predetermined time, and then fired using a firing profile in which it was cooled at a rate of 10°C/sin. As a result, a disk-shaped semiconductor porcelain with a diameter of 17.5 cm and a thickness of 0.6 cm 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, we determined the specific resistance of each sample at room temperature (25°C). The withstand voltage and Chierly point 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. Semiconducting agent. Table 2 shows the respective measurement results. In the table, samples Arashi 7 to 10, Arashi 14, 15, and -7 to 20 are within the scope of the present invention, and the other marks are outside the scope of the present invention. As is clear from the table, when the addition 1 of each main component is outside the specified range (-1 to 5), the withstand voltage of chair 1 is 63
Low, less than V/m. Also, MnO. The amount of addition, Sin. If the amount of addition exceeds the specified range 4 (-16, Arashi 11-13
), the withstand voltage characteristics can be achieved at full capacity, but the specific resistance is 12.9 to 43. Ω・Ro is high. Furthermore, SiO2
When the amount of addition is 0 (Arashi 6), the specific resistance is 11.7
Ω・1. Withstand voltage B is 70V/m, and the specific resistance of each sample is 70V/m. Satisfactory characteristics have not been obtained for both 1-voltage resistance. On the other hand, when each addition amount is within the range of the present invention (N
7-10, Nal4.15, IlkL17-20》
The Chierly point of the G deviation is 103 to 115°C, and the specific resistance is 5.
Low resistance of 0 to 9.7Ω, and withstand voltage of 118 to 180
It can be seen that a satisfactory value was obtained (V/Tsuru). [Effects of the Invention] As described above, according to the barium titanate-based semiconductor ceramic composition of the present invention, BaTiO*30 ~95mOJ%
, C a T I Os 3 ~25m
ol %, S r T I Os1 ~2
5moj%, PbTiOs1~30
mol% is the product, and 0.2 to 1 mol% of the semiconducting agent is added to this.
．． While adding 0 mol%, converting Mn to MnO, 0.03 to 0.1 mol%, Si
Os 0.01mol% or more 0.5 Cabinet ol%
Since the added content of less than
It is possible to obtain a semiconductor ceramic useful as a low-resistance circuit element, as well as to obtain a resistivity of 10Ω.m or more and a resistivity of 10Ω·1 or less.

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 has a content of 0.2 to 1.
0 mol% added and contained, manganese is 0.03 to 0.1 mol% converted to MnO_2, and silica is 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%, respectively.