JP2007173313A - Current-voltage nonlinear resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current-voltage nonlinear resistor contributive to miniaturization of a lightning arrester in which the resistance, nonlinear resistance characteristics and thermal stability can be enhanced by specifying the composition range of subcomponents. <P>SOLUTION: The current-voltage nonlinear resistor principally comprises zinc oxide (ZnO) and contains bismuth (Bi), cobalt (Co), manganese (Mn), antimony (Sb), nickel (Ni), gallium (Ga), and rare earth element (R), as subcomponents, in the range of 0.3-1.5 mol% in terms of Bi<SB>2</SB>O<SB>3</SB>, 0.3-2.0 mol% in terms of Co<SB>2</SB>O<SB>3</SB>, 0.4-3 mol% in terms of MnO, 0.5-4 mol% in terms of Sb<SB>2</SB>O<SB>3</SB>, 0.5-4 mol% in terms of NiO, 0.0005-0.02 mol% in terms of Ga<SP>3+</SP>, and 0.05-1.0 mol% in terms of R<SB>2</SB>O<SB>3</SB>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a current-voltage non-linear resistor whose main component is zinc oxide (ZnO), and more particularly to a current-voltage non-linear resistor in which the component configuration of subcomponents contained in the main component is improved. Is.

  Generally, overvoltage protection devices such as lightning arresters and surge absorbers are incorporated in power systems and electronic equipment circuits. This is a device for removing an overvoltage superimposed on a normal voltage and protecting a power system and an electronic device circuit. Such overvoltage protection devices often use current-voltage non-linear resistors. A current-voltage non-linear resistor is a resistor that has a property of substantially exhibiting insulation characteristics at a normal voltage and having a low resistance value when an overvoltage is applied.

  The current-voltage non-linear resistor is a ceramic element mainly composed of zinc oxide (ZnO), and the characteristics required there are as follows. That is, not only the non-linear resistance characteristics, whose resistance value changes greatly with voltage changes, but also life characteristics that do not deteriorate even if voltage is applied for a long period of time, and they can be destroyed even if lightning surge or switching surge is applied. Energy withstand characteristics that can be absorbed. Further, the current-voltage nonlinear resistor has a property that the resistance value decreases as the temperature increases. For this reason, the thermal stability with respect to high temperature is also calculated | required.

Here, a manufacturing procedure of the current-voltage nonlinear resistor will be described (see Patent Document 1). The current-voltage nonlinear resistor is made of zinc oxide (ZnO) as a main component and Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O ₃ , and NiO added as subcomponents. These raw materials are sufficiently mixed with water and a binder, and then granulated with a spray dryer or the like, and a sintered body is obtained by molding and sintering. Thereafter, an insulating material for preventing creeping flash is applied to the side surface of the sintered body, and a side surface insulating layer is formed by heat treatment. And the current-voltage nonlinear resistor is produced by grind | polishing the both end surfaces of a sintered compact, and attaching an electrode.

  By the way, along with the recent increase in power demand and demand for stabilization, there is an urgent need to reduce the size of power transmission and transformation equipment. Current-voltage nonlinear resistors mainly composed of zinc oxide (ZnO) are used in lightning arresters that are overvoltage protection devices due to their excellent nonlinear resistance characteristics. This reduces the number of current-voltage non-linear resistors stacked on the substrate. In other words, improvement of the resistance value of the current-voltage nonlinear resistor is an indispensable technical element for achieving miniaturization and reduction of the lightning arrester. Further, improving the non-linear resistance characteristics of the current-voltage non-linear resistor lowers the insulation level of the transmission / transformation system, leading to a reduction in size and size of the transmission / transformation equipment.

Against this background, various current-voltage nonlinear resistors that have improved nonlinear resistance characteristics have been proposed. For example, the current-voltage nonlinear resistor disclosed in Patent Document 2 limits the contents of subcomponents such as Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O ₃ , NiO, etc. The crystal phase of Bi ₂ O ₃ contained in the sintered body containing zinc oxide (ZnO) as a main component is limited, the resistance value can be increased, and excellent non-linear resistance characteristics can be exhibited.

In addition, the techniques disclosed in Patent Documents 3 to 5 are based on current-voltage non-consumption, which includes zinc oxide (ZnO) as a main component and Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O _{3 and the} like as subcomponents. In the linear resistor, by adding a rare earth oxide, the resistance value is increased to improve the characteristics.

Japanese Patent Publication No. 4-25681 JP 2001-307909 A Japanese Patent No. 2933881 Japanese Patent No. 2940486 Japanese Patent No. 3165410

  However, as the capacity of substations increases and the demand for underground substations increases, the demand for downsizing of transmission and substation equipment tends to increase. For this reason, an increasingly higher level is required for the required characteristics for the current-voltage nonlinear resistor, and it has been difficult for the above-described conventional technology to satisfy the current required characteristics. Specifically, when the electrical charge rate (the voltage normally applied to the current-voltage nonlinear resistor) is set high, the conventional current-voltage nonlinear resistor is severely deteriorated, and sufficient life characteristics are obtained. There were cases where it was not possible.

  In addition, downsizing of power transmission and substation equipment has of course extended to miniaturization of lightning arresters, but when current-voltage nonlinear resistors are increased in resistance with the miniaturization of lightning arresters, the following problems occur: A point has been pointed out. That is, the amount of surge energy absorbed increases in proportion to the increase in resistance of the current-voltage non-linear resistor, so that when the surge energy is absorbed, the heat generation temperature due to Joule heating of the current-voltage non-linear resistor also increases. Become.

  As described above, the current-voltage nonlinear resistor has a property that the resistance value decreases when the temperature increases. Therefore, when the temperature becomes too high, the resistance value decreases and the leakage current increases. That is, it has been pointed out that the current-voltage nonlinear resistor with high resistance has a problem in thermal stability because the degree of decrease in resistance value increases as the temperature rises.

  As a result, thermal runaway occurs due to the commercial frequency current after absorption of surge energy, and non-uniform heat generation increases in the current-voltage nonlinear resistor. This causes an increase in thermal stress, which may lead to destruction of the current-voltage nonlinear resistor. Therefore, unless the excellent thermal stability is ensured, the current-voltage nonlinear resistor cannot be sufficiently increased in resistance, and it is difficult to cope with the miniaturization of the lightning arrester.

  The present invention has been proposed in view of the above points, and its purpose is to increase the resistance value, nonlinear resistance characteristics, and thermal stability by defining the composition range of the subcomponents, An object of the present invention is to provide a current-voltage nonlinear resistor that can contribute to miniaturization of a lightning arrester.

The present invention has been proposed in order to achieve the above-described object, and has zinc oxide (ZnO) as a main component and bismuth (Bi), cobalt (Co), manganese (Mn), antimony (Sb) as subcomponents. ), Nickel (Ni), gallium (Ga), and rare earth element (R) converted to Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O ₃ , NiO, Ga ³⁺ , and R ₂ O ₃ , respectively. , _Bi 2 _{O 3} to 0.3~1.5mol%, _Co 2 _{O 3} and 0.3~2.0mol%, 0.4~3mol% of MnO, 0.5~4mol% of _Sb 2 _{O 3,} NiO and _0.5~4mol%, 0.0005~0.02mol% of ^{Ga _3+,} is characterized in that it comprises R 2 _{O 3} in the range of 0.05~1.0mol%.

  In the present invention, the subcomponents are defined in the above composition range. This is the result of the inventor's various studies on the component composition of the current-voltage nonlinear resistor in order to achieve the above-described object. This is because good resistance, non-linear resistance characteristics and thermal stability can be obtained when the composition is within the above composition range, and conversely, the above characteristics are deteriorated when the composition range is exceeded. . That is, by keeping the composition component of the subcomponent within the above composition range, a high resistance value is ensured and the non-linear resistance characteristic and the thermal stability are improved, thereby achieving a high level required characteristic required at present. I can respond.

  In the present invention, subcomponents such as bismuth (Bi), cobalt (Co), manganese (Mn), antimony (Sb), nickel (Ni), gallium (Ga), and rare earth elements (R) It is possible to provide a current-voltage nonlinear resistor that can obtain excellent resistance value, nonlinear resistance characteristics, and thermal stability, and can contribute to miniaturization of a lightning arrester. it can.

  Hereinafter, embodiments according to the present invention will be specifically described with reference to FIGS. 1 and 2 and Tables 1 to 5. FIG. Tables 1 to 5 are lists showing the contents of current-voltage nonlinear resistors produced by changing the contents of the subcomponents in various ways and evaluation indices. Among the sample numbers shown in each table, those marked with * have subcomponents outside the composition range according to the present invention, and are comparative samples prepared for comparison. On the other hand, those not marked with * have subcomponents within the composition range corresponding to the present invention.

(1) 1st Embodiment 1st Embodiment which concerns on this invention is described with reference to FIG. 1, Table 1, and Table 2. FIG. FIG. 1 shows a cross-sectional view of a current-voltage nonlinear resistor according to this embodiment.

(Constitution)
In this embodiment, zinc oxide (ZnO) is used as the main component. Further, as subcomponents, bismuth (Bi), cobalt (Co), manganese (Mn), antimony (Sb), nickel (Ni) are used, and the subcomponents are defined as Bi. _In terms of ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O ₃ , and NiO, they are included in the following ranges.

That, _Bi 2 _{O 3} to 0.3~1.5mol%, _Co 2 _{O 3} and 0.3~2.0mol%, 0.4~3.0mol% of MnO, the _Sb 2 _{O 3} 0.5 to It contains 4.0 mol%, NiO 0.5-4.0 mol%, and Ga3 ⁺ 0.0005-0.02 mol%.

Further, at least one rare earth element (R) among dysprosium (Dy), europium (Eu), erbium (Er), thulium (Tm), gadolinium (Gd), yttrium (Y), holmium (Ho), and ytterbium (Yb). )) In an amount of 0.05 to 1.0 mol% in terms of R ₂ O ₃ .

(Production procedure)
Here, a procedure for producing the current-voltage nonlinear resistor and the comparative sample according to the present embodiment will be specifically described. As a subcomponent with respect to ZnO as the main component, the component content of the current-voltage nonlinear resistor finally obtained is the value of sample number 1 to sample number 44 shown in Tables 1 and 2. Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O ₃ , NiO, Dy ₂ O ₃ and Ga ³⁺ or Al ³⁺ are weighed in predetermined amounts, and this raw material is mixed with water and organic binders in a mixing device. Then, each uniform slurry was prepared. Here, Ga ³⁺ or Al ³⁺ is added as an aqueous nitrate solution.

  Next, each obtained slurry was spray-granulated with a spray dryer to prepare granulated powder having a particle size of about 100 μm. The obtained granulated powder was put into a mold and pressurized, formed into a disk having a diameter of 125 mm and a thickness of 30 mm, and the molded body was heated to 500 ° C., thereby removing the added organic binders.

  Thereafter, the sintered body 1 was further fired at 1100 ° C. for 2 hours to obtain a sintered body 1 as shown in FIG. Further, an inorganic insulating material was applied to the side surface of the sintered body 1 and heat-treated to form the side surface insulating layer 2. Finally, the upper and lower end surfaces of the sintered body 1 provided with the side surface insulating layer 2 are polished to a predetermined thickness, and then the electrode 3 is sprayed on the polished surface of the sintered body 1, whereby a current-voltage non-linear resistor. Was made.

(Evaluation of resistance value)
The characteristics of various current-voltage non-linear resistors produced by the above procedure were evaluated as follows. First, for the resistance value of the current-voltage non-linear resistor, the operation start voltage of the current-voltage non-linear resistor (voltage when an alternating current of 1 mA was applied, V _{1 mA} ) was measured. As the operation start voltage is higher, the number of current-voltage non-linear resistors stacked on the lightning arrester can be reduced, which is effective as an index for grasping the degree of miniaturization of the lightning arrester.

(Evaluation of non-linear resistance characteristics)
Furthermore, the voltage (V _{10 kA} ) when an 8 × 20 μs impulse current of 10 kA was passed was measured, and the ratio (V _{10 kA} / V _{1 mA} ) to the operation start voltage (V _{1 mA} ) was evaluated as a non-linearity coefficient. The smaller the value of this nonlinearity coefficient, the better the nonlinear resistance characteristic.

(Evaluation of thermal stability)
As thermal stability evaluation in the current-voltage non-linear resistor, resistance leakage current was measured and evaluated when an AC voltage of 90% of the operation start voltage was applied in a 200 ° C. thermostat. That is, the smaller the high-temperature leakage current at 200 ° C., the better the thermal stability. In addition, the element from which an additive component composition differs measured 10p at each composition, and made the average value the value of the composition. The measurement results are shown in Tables 1 and 2.

(Function and effect)
As described above, the current-voltage non-linear resistors with sample numbers marked with * shown in Tables 1 and 2 have compositions outside the scope of claims of the present invention, and are prepared for comparison. This is a sample. As is clear from the results shown in Tables 1 and 2, the characteristics of the comparative sample indicate that the conditions of the excellent current-voltage nonlinear resistor specified below are not satisfied.
Operation start voltage (V _{1 mA} )> 400 V / mm
Non-linearity coefficient (V _{10 kA} / V _{1 mA} ) <1.50
High temperature leakage current (200 ° C) <15 mA

  On the other hand, the current-voltage non-linear resistors of the sample numbers not marked with * shown in Tables 1 and 2 define the operation start voltage by defining the composition range within the claims of the present invention. It shows that both the non-linearity coefficient and the high temperature leakage current are excellent. That is, it can be said that the current-voltage nonlinear resistor according to the present embodiment has a high resistance value and is excellent in nonlinear resistance characteristics and thermal stability.

  Subsequently, the function of each of the subcomponents included in this embodiment will be described, and it will be mentioned that the comparative sample does not reach the characteristics of this embodiment.

(Function of Bi ₂ O ₃ ) ... See Table 1 Bi ₂ O ₃ is a component that exists at the grain boundary of zinc oxide (ZnO), which is the main component of the sintered body, and exhibits nonlinear resistance characteristics. It works to promote crystal grain growth. Here, when sample numbers 1 to 6 are compared, if the amount of Bi ₂ O ₃ is less than 0.3 mol% (sample number 1), the amount of Bi ₂ O ₃ that becomes a liquid phase at the time of sintering and increases the sinterability is insufficient. It is.

For this reason, excellent characteristics in non-linearity and high-temperature leakage current are not obtained. If the amount of Bi ₂ O ₃ exceeds 1.5 mol% (Sample No. 6), the ZnO particles grow too much during sintering, so that a sufficiently high operation starting voltage cannot be obtained.

(Function of Sb ₂ O ₃ ) ... Refer to Table 1 Sb ₂ O ₃ forms spinel (Zn ₇ Sb ₂ O ₁₂ ) particles together with zinc oxide (ZnO) to control the growth of ZnO particles during sintering, and is uniform It is a component to improve the non-linear resistance characteristic and at the same time has a function of suppressing grain growth of ZnO crystal.

Comparing Sample Nos. 3 and 7 to 12, when the amount of Sb ₂ O ₃ is less than 0.5 mol% (Sample No. 7), the amount of spinel particles that can suppress grain growth during sintering is too short, so the operation start voltage, non- In the linearity, an excellent characteristic cannot be obtained. Further, when the amount of Sb ₂ O ₃ exceeds 4 mol% (Sample No. 12), since there are too many spinel particles acting as an insulating component in the sintered body, excellent characteristics in non-linearity and high-temperature leakage current Will not be able to get.

(Function of MnO) ... see Table 1 MnO is a component that is mainly dissolved in spinel particles to improve nonlinear resistance characteristics. Comparing sample numbers 3 and 13 to 18, when the amount of MnO is less than 0.4 mol% (sample number 13), the electrical characteristics of the ZnO grain boundary become unstable, so that excellent non-linearity cannot be obtained. In addition, when the amount of MnO exceeds 3 mol% (sample number 18), it is impossible to obtain excellent non-linear characteristics.

(Function of NiO) ... See Table 1 NiO is also a component that improves the non-linear resistance characteristics by being mainly dissolved in spinel particles, like MnO. Comparing sample numbers 3 and 19 to 24, when the amount of NiO is less than 0.5 mol% (sample number 19), the amount of NiO dissolved in the spinel particles decreases, so that excellent operation start voltage and nonlinearity are obtained. I can't. On the other hand, when the amount of NiO exceeds 4 mol% (sample number 24), the electrical characteristics of the ZnO grain boundary become unstable, so that excellent non-linear characteristics and high-temperature leakage current characteristics cannot be obtained.

(Function of Co ₂ O ₃ ) ... Refer to Table 2 Co ₂ O ₃ is also a component that is mainly dissolved in spinel particles to improve the non-linear resistance characteristics. Comparing sample numbers 3 and 25-30, when the amount of Co ₂ O ₃ is less than 0.3 mol% (sample number 25), the electrical characteristics of the ZnO grain boundary become unstable, and thus excellent nonlinearity can be obtained. If the amount of Co ₂ O ₃ exceeds 2 mol% (Sample No. 30), the electrical characteristics of the ZnO grain boundary become unstable, so that excellent non-linear characteristics and high-temperature leakage current characteristics can be obtained. I can't.

(Functions of ^{Ga 3+)} ... see Table 2 Ga ³⁺ is dissolved in ZnO particles, and serve to enhance the non-linear resistance characteristics by reducing the electrical resistance of the ZnO particles. Aluminum (Al) is widely used in the prior art as a component that performs the same function, but current-voltage nonlinearity with superior thermal stability is achieved by adding Ga rather than Al to improve nonlinear resistance characteristics. A resistor is obtained.

Comparing sample numbers 3 and 31 to 38, when the amount of Ga ³⁺ is less than 0.0005 mol% (sample number 31), the amount of Ga ³⁺ dissolved in the ZnO particles in the sintered body is not sufficient. The electrical resistance becomes high and excellent non-linearity cannot be obtained.

Further, when the amount of Ga ³⁺ is more than 0.02 mol% (sample number 37), Ga ³⁺ precipitates at the ZnO grain boundary and deteriorates the electrical characteristics of the ZnO grain boundary, so that excellent non-linearity can be obtained. Can not. Furthermore, superior high-temperature leakage current characteristics can be obtained when Ga ³⁺ is added as compared with the case where Al ³⁺ is added (Sample No. 38).

(Function of Dy ₂ O ₃ ) ... See Table 2 By the way, in order to increase the resistance of the current-voltage nonlinear resistor, the amount of the additive of Sb ₂ O ₃ , Co ₂ O ₃ , NiO, and MnO is arbitrarily set. If the number is increased, the temperature dependence of the resistance value increases, and the thermal stability decreases.

Therefore, in the present embodiment, the resistance is increased by adding the rare earth oxide Dy ₂ O ₃ having the effect of increasing the resistance, and the additive amounts of Sb ₂ O ₃ , Co ₂ O ₃ , NiO, and MnO are relatively increased. By reducing the temperature dependence of the resistance value, the thermal stability of the current-voltage nonlinear resistor is improved.

Comparing sample numbers 3 and 39 to 44, when the amount of Dy ₂ O ₃ is less than 0.3 mol% (sample number 39), the amount of Dy ₂ O ₃ having an effect of suppressing grain growth is insufficient, and thus excellent. The operation start voltage and non-linearity cannot be obtained. On the other hand, when the amount of Dy ₂ O ₃ exceeds 1.0 mol% (sample number 44), the electrical characteristics of the ZnO grain boundary become unstable, and excellent characteristics cannot be obtained in terms of nonlinearity and high-temperature leakage current.

  In this embodiment, dysprosium (Dy) oxide is used as the rare earth oxide, but other rare earth elements include europium (Er), erbium (Er), thulium (Tm), and gadolinium (Gd). ), Yttrium (Y), holmium (Ho), and ytterbium (Yb) oxide, the same effect as that of dysprosium (Dy) oxide can be obtained. Moreover, if the content of each rare earth oxide finally falls in the range of 0.05 to 1.0 mol%, the combination can be selected as appropriate.

  As described above, in the present embodiment, zinc oxide (ZnO) is the main component, and the final subcomponent content is in the above range, thereby having a high resistance value, excellent thermal stability and A current-voltage non-linear resistor having non-linear resistance characteristics can be obtained. For this reason, a reduction in the number of stacked current-voltage nonlinear resistors can be realized with high reliability, which can contribute to miniaturization of the lightning arrester.

(2) Second embodiment (configuration and manufacturing procedure)
Next, a second embodiment according to the present invention will be described with reference to Table 3. The present embodiment is characterized by comprising a sintered body containing 0.005 to 0.05 wt% of silver (Ag) in terms of Ag ₂ O.

That is, with respect to ZnO as the main component, Bi ₂ O ₃ as the subcomponent is finally 0.5 mol%, Co ₂ O ₃ and MnO are respectively 1.0 mol%, Sb ₂ O ₃ and NiO, respectively. 2 mol%, Dy ₂ O ₃ is 0.5 mol%, and Ga ³⁺ is nitrate aqueous solution and weighed to 0.003 mol% and added. Further, Ag ₂ O was added to the basic composition so as to contain 0.001 to 0.1 wt%, and the sample number 45 to sample number 50 shown in Table 3 were used by the method shown in the first embodiment. A current-voltage non-linear resistor was produced.

(Evaluation of life characteristics)
The life characteristics of these current-voltage nonlinear resistors were evaluated. In the evaluation of the life characteristics, the voltage (V _{1 mA} ) when a current of 1 mA flows was continuously applied for 3000 h in the atmosphere at 120 ° C., and the change rate of the leakage current (I _r ) when V _{1 mA} before and after that was applied. And are shown in Table 3.

Where the rate of change is
(I _r (after 3000 h) −I _r (initial value)) / I _r (initial value) × 100
If the value of this leakage current change rate is a negative value, it indicates that the life characteristics of the current-voltage nonlinear resistor are excellent.

(Function and effect)
The current-voltage nonlinear resistors of sample numbers 45 and 50 marked with * in Table 3 have compositions outside the scope of the present invention. As is apparent from the results shown in Table 3, the characteristics of the comparative sample indicate that the rate of change in leakage current is a positive value and the life characteristics are low. That is, when the added amount of Ag is less than 0.005 wt% in terms of Ag ₂ O, the effect of improving the life characteristics cannot be obtained. On the other hand, if it exceeds 0.05 wt%, the life characteristics will be deteriorated.

In contrast, in the present embodiment that the content of Ag ₂ O to 0.005 to 0.05% (article No. 46 to 49), the rate of change of the leakage current is a negative value (see Table 3), It is clear that current-voltage nonlinear resistors with excellent lifetime characteristics can be obtained.

That is, according to the present embodiment, by adding 0.005 to 0.05 wt% of Ag in terms of Ag ₂ O, the change in leakage current with time can be reduced and the life characteristics can be improved. In the present embodiment, the effect of addition of Ag on the life characteristics was described only for the basic composition shown in the configuration and the manufacturing procedure. An effect is obtained.

(3) Third embodiment (configuration and manufacturing procedure)
Subsequently, a third embodiment according to the present invention will be described with reference to Table 4. This embodiment is characterized in that it is made of a sintered body containing 0.005 to 0.05 wt% of boron (B) in terms of B ₂ O ₃ .

That is, with respect to ZnO as the main component, Bi ₂ O ₃ as the subcomponent is finally 0.5 mol%, Co ₂ O ₃ and MnO are respectively 1.0 mol%, Sb ₂ O ₃ and NiO, respectively. 2 mol%, Dy ₂ O ₃ 0.5 mol%, and Ga ³⁺ as a nitrate aqueous solution are weighed to 0.003 mol% and added. The steps so far are the same as in the second embodiment.

Furthermore, B ₂ O ₃ was added to the basic composition so as to contain 0.001 to 0.1 wt%, and the sample number 51 shown in Table 4 was used by the method shown in the first embodiment. A current-voltage nonlinear resistor serving as sample number 56 was produced. That is, in the third embodiment, B ₂ O ₃ is contained in the range of 0.001 to 0.1 wt% in place of Ag ₂ O in the second embodiment.

(Evaluation of life characteristics)
The life characteristics of these current-voltage nonlinear resistors were evaluated by the same method as that shown in the second embodiment. Table 4 shows the leakage current change rate in the third embodiment.

(Function and effect)
The current-voltage nonlinear resistors of sample numbers 51 and 56 marked with * shown in Table 4 have compositions outside the scope of claims of the present invention, and as shown in Table 4, comparative samples The characteristics in (2) indicate that the rate of change in leakage current is a positive value and the life characteristics are low.

That is, when the addition amount of B is converted to B ₂ O ₃ and less than 0.005 wt% and more than 0.05 wt%, the life characteristics are low. On the other hand, in this embodiment (material numbers 52 to 55) in which the content of B ₂ O ₃ is 0.005 to 0.05 wt%, the change rate of the leakage current is a negative value (see Table 4). Thus, a current-voltage nonlinear resistor having excellent life characteristics is obtained.

That is, according to the present embodiment, life characteristics can be improved by adding 0.005 to 0.05 wt% of B in terms of B ₂ O _{3 as} in the second embodiment. In the present embodiment, only the basic composition has an effect of adding to the life characteristics of B. However, the same effect can be obtained within the basic composition range of claim 1. Furthermore, Ag and B may be added at the same time as long as they are not in the range of 0.005 to 0.05 wt%.

(4) Fourth embodiment (configuration and fabrication procedure)
A fourth embodiment according to the present invention will be described. In this embodiment, with respect to ZnO as a main component, Bi ₂ O ₃ as subcomponents is finally added at 0.5 mol%, Co ₂ O ₃ and MnO are respectively 1.0 mol%, Sb ₂ O ₃ and NiO. 2 mol%, Dy ₂ O ₃ 0.5 mol%, and Ga ³⁺ 0.003 mol%, respectively, and added, respectively, by the method shown in the first embodiment, the current-voltage A non-linear resistor was produced. Here, this embodiment is characterized in that Ga ³⁺ is added as an aqueous nitrate solution.

(Evaluation of resistance value stability)
In the fourth embodiment, the stability of the resistance value is evaluated. That is, the operation start voltage (V _{1 mA} ) was measured for each current-voltage nonlinear resistor 100p to which Ga ³⁺ was added in an aqueous nitrate solution, and the standard deviation of the operation start voltage was calculated. Further, as a comparative example, the operation start voltage (V _{1 mA} ) is measured for each of the current-voltage nonlinear resistors 100p in which these Ga ³⁺ are added as oxides instead of an aqueous solution, and the standard deviation of the operation start voltage is measured. Was calculated.

(Function and effect)
As a result of calculating the standard deviation regarding this embodiment and the comparative example, the standard deviation of V1 mA when Ga ³⁺ is added in an aqueous nitrate solution is 585, and the standard deviation of V1 mA when Ga ³⁺ is added as an oxide. Was 2406. That is, a current-voltage non-linear resistor with less variation in characteristics can be obtained when it is added remarkably in a nitrate aqueous solution.

Since the addition amount of gallium (Ga) is very small, for example, when gallium oxide (Ga ₂ O ₃ ), which is an oxide of gallium (Ga), is added, it is uniformly mixed with other raw materials. Is difficult, and variation in characteristics increases. On the other hand, for example, when gallium nitrate (Ga (NO ₃ ) ₃ ), which is a water-soluble gallium raw material, is added, it is mixed with other raw materials as gallium ions, so that good characteristic stability can be obtained. Conceivable.

(5) Fifth embodiment (configuration and manufacturing procedure)
A fifth embodiment according to the present invention will be described with reference to Table 5. In this embodiment, with respect to ZnO as a main component, Bi ₂ O ₃ as subcomponents is finally added at 0.5 mol%, Co ₂ O ₃ and MnO are respectively 1.0 mol%, Sb ₂ O ₃ and NiO. Are respectively weighed to ₂ mol% and Dy ₂ O ₃ to 0.5 mol% and added.

Furthermore, a current-voltage non-linear resistor having sample numbers 57 to 71 shown in Table 5 was fabricated by the method shown in the first embodiment, using Ga ³⁺ as nitrate and changing the addition amount. . However, here, the disk diameter of the current-voltage nonlinear resistor was set to 35 mm, 60 mm, and 100 mm, and the Ga ³⁺ addition amount was changed in each disk diameter.

These current-voltage nonlinear resistors were evaluated for nonlinearity (V _{10 kA} / V _{1 mA} ) by the method shown in the first embodiment, and are shown in Table 5. The coefficient A in Table 5 is a coefficient in the following Ga ³⁺ addition amount and a relational expression.

This embodiment is characterized in that the coefficient A is in the range of 5-14.
Ga ³⁺ addition amount (mol%) = (A−0.042 × D) / 1000
(A: coefficient, D = disk diameter (mm))

(Function and effect)
FIG. 2 shows the relationship between the coefficient A and nonlinearity. As shown in FIG. 2, it is clear that the nonlinearity changes depending on the difference in the amount of gallium (Ga) added. At this time, in the case of a disk shape, in the current-voltage nonlinear resistor, the amount of gallium added for improving the nonlinearity varies depending on the disk diameter. This is because the current density in the current-voltage nonlinear resistor changes depending on the disc diameter, and the optimum gallium addition amount is within the range of the relational expression.

That is, as apparent from FIG. 2, when the coefficient A is in the range of 5 to 14, it is an optimum region for obtaining excellent nonlinearity regardless of the disk diameter of the current-voltage nonlinear resistor. I know that there is. The present embodiment having a Ga ³⁺ addition amount with a coefficient A of 5 to 14 can obtain very excellent non-linear resistance characteristics.

(6) Other Embodiments The present invention is not limited to the above embodiment, and bismuth (Bi), cobalt (Co), manganese (Mn), antimony (Sb), nickel (Ni), gallium. With respect to subcomponents such as (Ga) and rare earth elements (R), and silver (Ag) and boron (B), all can be changed as long as they are within the composition range indicated in the claims.

Sectional drawing of the current-voltage nonlinear resistor which concerns on this invention. The relationship figure of Ga3 ⁺ addition amount coefficient A and nonlinearity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sintered body 2 ... Side surface insulating layer 3 ... Electrode

Claims (6)

Main component is zinc oxide (ZnO), and bismuth (Bi), cobalt (Co), manganese (Mn), antimony (Sb), nickel (Ni), gallium (Ga), and rare earth elements (R) are subcomponents. Current-voltage nonlinear resistor,
Said subcomponent, _{respectively, Bi 2 O 3, Co 2} O 3, MnO, Sb 2 O 3, NiO, Ga 3+, in terms of R 2 _{O 3,}
0.3~1.5mol% of Bi ₂ O _3,
0.3～2.0Mol% of Co ₂ O _3,
0.4 to 3.0 mol% of MnO,
0.5~4.0mol% of Sb ₂ O _3,
NiO 0.5-4.0 mol%,
Ga ³⁺ is 0.0005 to 0.02 mol%,
0.05~1.0mol% of the R ₂ O _3,
A current-voltage non-linear resistor comprising:   The rare earth element (R) includes at least one of dysprosium (Dy), europium (Eu), erbium (Er), thulium (Tm), gadolinium (Gd), yttrium (Y), holmium (Ho), and ytterbium (Yb). The current-voltage nonlinear resistor according to claim 1, wherein the current-voltage nonlinear resistor is included. 3. The current-voltage nonlinear resistor according to claim 1, comprising a sintered body containing 0.005 to 0.05 wt% of silver (Ag) in terms of Ag ₂ O. 4. In terms of boron (B) to the _B 2 _{O 3,} the current according to any one of claims 1 to 3, characterized in that a sintered body containing 0.005 to 0.05% - Voltage Non Linear resistor.   The current-voltage nonlinear resistor according to any one of claims 1 to 4, wherein a water-soluble raw material is used as an additive raw material for gallium (Ga). The current-voltage nonlinear resistor is shaped like a disk,
The relationship between the additive amount of Ga ³⁺ and the diameter of the disc is
Ga ³⁺ addition amount (mol%) ≦ (A−0.042 × D) / 1000
(A = 5-14, D = disk diameter (mm))
The current-voltage nonlinear resistor according to any one of claims 1 to 4, wherein

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