JP5831079B2 - Dielectric porcelain composition and electronic component - Google Patents

Description

  The present invention relates to a dielectric ceramic composition and an electronic component. More specifically, the dielectric ceramic composition capable of obtaining good dielectric constant and temperature characteristics in a wide temperature range and the dielectric ceramic composition are used. It relates to electronic components.

Conventionally, as electronic parts such as dielectric ceramic compositions and dielectric ceramic capacitors and piezoelectric elements, for example, ceramic compositions containing (Ba, Sr, Ca) (Ti, Zr) O ₃ as main components have been used. (For example, see Patent Documents 1 to 3)
In these compositions, for example, BaTiO ₃ has a Curie point of around 125 ° C., and in a high temperature region of 150 ° C. or higher, it is greatly reduced compared to the relative dielectric constant at room temperature, and in a region of 100 ° C. or higher. Since the relative dielectric constant is remarkably increased as compared to room temperature because it is in the vicinity of the Curie point, the temperature change rate of the relative dielectric constant is very large and cannot be practically used. For this reason, for example, rare earth elements are mixed as subcomponents to control the temperature dependence of the relative permittivity at −55 ° C. to 150 ° C., which is a practical range for ceramic capacitors, and has been widely used in the industrial field.

JP 2007-169090 A JP 2006-342025 A JP, 2005-194138, A For example, a two-component dielectric ceramic component as shown by PbTiO3-BaZrO3 uses a PbTiO3 Curie point of around 490 ° C, so that the dielectric constant is about 300 ° C. The temperature dependence of the rate can be made relatively small, but Pb must be used for the composition.

  On the other hand, niobic acid-based piezoelectric ceramic compositions that do not contain lead are well known. (For example, refer to Patent Documents 4 to 6), however, none of the documents disclose the temperature dependency of the relative permittivity in a wide temperature range for the dielectric ceramic composition. Further, Patent Document 6 attempts to reduce the temperature dependence of the relative permittivity over a wide temperature range, but the capacitance change rate (in the range of −55 ° C. to 400 ° C.) ΔC / C) exceeds ± 22%, and it cannot be said that satisfactory characteristics are necessarily obtained. In addition, the withstand voltage is not specified.

JP 2003-252681 A JP 2009-227482 A JP 2009-249244 A

  For example, in electronic parts for on-vehicle applications, conventionally, for example, a dielectric that satisfies a capacitance change rate within ± 22% (ΔC / C = within ± 22%) in EIA standard X8S (−55 ° C. to 150 ° C.), for example. A body porcelain capacitor is needed. In order to increase the space in the car and obtain a more comfortable driving environment, the electronic components are used closer to the car engine area, so they are guaranteed by the currently specified EIA standard. There is a demand for a dielectric ceramic capacitor that satisfies ΔC / C = ± 22% even in a temperature range higher than the maximum temperature and exceeding 150 ° C.

  Furthermore, the operating temperature range of power devices using SiC or GaN-based semiconductors is beginning to be required up to a high temperature range around 400 ° C., and for use as a smoothing capacitor, for example, a temperature range of −55 to 400 ° C. Also, it is preferable that ΔC / C = ± 22%. However, no description has been made about a dielectric ceramic composition satisfying ΔC / C = ± 22% within a temperature range of −55 to 400 ° C.

In addition, a dielectric ceramic capacitor that can satisfy EIA standard X8S, for example, a dielectric ceramic capacitor mainly composed of BaTiO ₃ , SrTiO ₃ , CaTiO _3, etc., is a rare earth element, such as Sc, Y, La, Ce. The characteristics are achieved by using rare earth elements such as Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. If the conventional EIA standard X8S characteristics can be achieved without using these rare earth elements, the conventional characteristics can be achieved without using rare elements, depending on market principles such as the recent rise in rare elements. Can be prevented.

Conventionally, there are dielectric ceramic capacitors that satisfy ΔC / C = ± 22% at a high temperature of 150 ° C. or higher by using, for example, PbTiO ₃ as a main component. However, since Pb exists in the composition, For example, PbO, PbO ₂ , Pb ₃ O ₄ or the like must be used, and in the production process, these raw materials may diffuse into the environment. Therefore, solving this requires harmony with the recent environment. It is promising as a technology.

  From the above viewpoint, the present invention has a small capacitance change rate (for example, ΔC / C = within ± 22%) in a wide temperature range (for example, −55 to 400 ° C.) and a high temperature around 400 ° C. To provide a lead-free niobic acid-based dielectric ceramic composition that has various characteristics up to the domain, has a large relative dielectric constant, and has a high withstand voltage, and an electronic component using the dielectric ceramic composition. Is an issue.

As a result of intensive studies in order to achieve the above object, the present inventors have found that the above object can be achieved by using a dielectric ceramic composition having a specific composition, and the present invention has been completed. .

That is, the dielectric ceramic composition according to the present invention for solving the above-mentioned problems is mainly composed of a first phase represented by the general formula KNbO ₃ and a second phase represented by the general formula BaTiO _3. When Mn and Si are contained as components and the main component is 100 mol% composed of the first phase and the second phase, the content of Mn is 0.5 mol% or more and 5.0 mol% in terms of MnCO _3. Hereinafter, the Si content satisfies 0.2 mol% or more and 3.0 mol% or less in terms of SiO ₂ , and the ratio of the first phase represented by the KNbO ₃ is a, and the BaTiO 3 is included. _{When the} ratio of the second phase represented by ₃ is b, the relationship 1.2 <a / b <5.7 is satisfied .

When the main component comprising the first phase and the second phase is 100 mol%, the Mn content is preferably 0.5 mol% or more and 5.0 mol% or less in terms of MnCO ₃ .

When a main component 100 mol% consisting of the first phase and a second phase, the content of the Si in terms of SiO _2, 0.2 mol% or more, it is desirable that less 3.0 mol%.

When the proportion of the first phase represented by KNbO ₃ is a and the proportion of the second phase represented by BaTiO ₃ is b, 1.2 <a / b <5.7. It is desirable to satisfy the relationship.

  Moreover, it is desirable to use these dielectric ceramic compositions as electronic parts such as dielectric ceramic capacitors and piezoelectric elements.

  According to the present invention, the main component has a capacitance change rate in a wide temperature range (for example, −55 to 400 ° C.) without using heavy metal elements that have an impact on the environment such as Pb, Bi, and Sb. It can be flattened within ± 22%, exhibiting good temperature characteristics and a high dielectric constant.

  Furthermore, according to the present invention, a dielectric ceramic composition that can exhibit a high relative dielectric constant in a wide temperature range, for example, has a characteristic of a relative dielectric constant of 500 or more at 25 ° C. is obtained.

  In addition, according to the present invention, by including Mn and Si as subcomponents, a relatively high withstand voltage is exhibited, so that an electronic component having a high rated voltage can be provided.

  Therefore, as a dielectric ceramic composition according to the present invention, smoothing for a power device using a SiC or GaN-based semiconductor, which is required to be used in a high temperature region, or to a higher temperature region, is required. It is most suitable as a capacitor for electric vehicles and an electronic component used for noise removal in the engine room of an automobile.

  Further, the dielectric ceramic composition according to the present invention can satisfy the EIA standard X8S characteristic (ΔC / C at −55 ° C. to 150 ° C. = within ± 22%), and therefore can be used as a capacitor having X8S characteristic.

  Hereinafter, the present invention will be described based on embodiments.

The dielectric ceramic composition according to the present embodiment has a main component composed of a mixed crystal of a first phase represented by a general formula KNbO ₃ and a second phase represented by a general formula BaTiO ₃ . It is characterized by containing Mn and Si elements as subcomponents.

By using the mixed crystal of KNbO ₃ and BaTiO ₃ as a main component, the high relative dielectric constant of BaTiO ₃ is utilized at 100 ° C. or lower, and the high relative dielectric constant of KNbO ₃ is obtained at 150 ° C. or higher. Can be used. As a result, a high relative dielectric constant of 500 or more can be exhibited at −55 to 400 ° C.

Furthermore, by setting the content ratio of KNbO ₃ and BaTiO ₃ to a specific ratio, the capacity-temperature characteristic in the above temperature range can be flattened, and the change rate of the capacitance is within a range of ± 22%. It becomes possible to do.

When the main component consisting of the first phase and the second phase is 100 mol%, the Mn content is less than 0.5 mol% in terms of MnCO ₃ , and the grain boundary resistance and the BaTiO ₃ insulation resistance are improved. Is not effective, a withstand voltage of 10 V / mm or more cannot be obtained. On the other hand, if it exceeds 5.0 mol%, it becomes difficult to obtain a dense sintered body, so that the withstand voltage is 10 V / mm or less. turn into.

For this reason, content of Mn is 0.5 mol% or more and 5.0 mol% or less in conversion of MnCO ₃ .

When the main component composed of the first phase and the second phase is 100 mol%, when the Si content is less than 0.2 mol% in terms of SiO ₂ , the grain boundary resistance and BaTiO ₃ and KNbO ₃ Is not effective in suppressing solid solution, and a withstand voltage of 10 V / mm or more cannot be obtained. On the other hand, if it exceeds 3.0 mol%, the paraelectric component increases and the relative dielectric constant is less than 500. End up.

Therefore, the content of Si in terms of SiO _2, 0.2 mol% or more, or less 3.0 mol%.

When the proportion of the first phase represented by KNbO ₃ is a and the proportion of the second phase represented by BaTiO ₃ is b, when a / b is 1.2 or less, , increases the proportion of second phase represented by BaTiO _3, the transition to the paraelectric of 0.99 ° C. subsequent BaTiO _3, capacity reduction becomes remarkable. For this reason, the deterioration of the capacity-temperature characteristic after 150 ° C. is remarkable, and it becomes impossible to satisfy the capacitance change rate within ± 22%.

On the contrary, when a / b is 5.7 or more, the proportion of the second phase represented by BaTiO ₃ decreases, and the transition from orthorhombic to tetragonal KNbO ₃ after 200 ° C., 400 ° C. Since the relative dielectric constant peak due to the transition from the nearby tetragonal crystal to the cubic crystal is prominent, the capacitance-temperature characteristic is greatly deteriorated in the temperature region of 150 ° C. or higher, and the capacitance change rate is within ± 22%. become unable.

Therefore, a and b satisfy the relationship 1.2 <a / b <5.7.

An electronic component according to the present invention is an electronic component having a dielectric and an electrode, and is a laminated type having a dielectric layer composed of the dielectric ceramic composition described above and an internal electrode layer Electronic components. Alternatively, electronic parts using the dielectric ceramic composition described above are not particularly limited, but include ceramic capacitors, piezoelectric elements, chip inductors, chip varistors, chip thermistors, chip resistors, and other surface mount (SMD) chip type electronic devices. Parts are illustrated.

In addition, by replacing a part of K of the first phase KNbO ₃ with at least one selected from Li and Na, or substituting a part of Nb with Ta for an appropriate amount, the capacity-temperature characteristics can be improved. It becomes possible to control more and good temperature characteristics can be obtained.

Replacing a part of Ba in the second phase BaTiO ₃ with at least one selected from Ca, Sr and Mg, or replacing a part of Ti with Zr, Hf, Co, V, Ta, Cr, By substituting an appropriate amount with at least one selected from Mo, W, and Mg, the capacity-temperature characteristic can be more controlled, and a favorable temperature characteristic can be obtained.

The dielectric ceramic composition according to the present embodiment takes a composite structure in which a first phase represented by KNbO ₃ and a second phase represented by BaTiO ₃ are set at a specific ratio. The dielectric constant is 500 or more, the capacitance change rate satisfies ± 22% in a wide temperature range of −55 to 400 ° C., and Mn and Si are contained to ensure a withstand voltage of 10 kV / mm or more. Is possible.

  As described above, since the dielectric ceramic composition according to the present embodiment exhibits good characteristics in a high temperature region, it is preferably used in a use temperature region (for example, 200 to 250 ° C.) of a SiC or GaN-based power device. Can do. Moreover, it is suitably used as an electronic component for noise removal in a harsh environment such as an automobile engine room.

    Next, an example of a method for producing a dielectric ceramic composition according to this embodiment will be described.

First, the raw material of the main component which comprises a dielectric ceramic composition is prepared. In the present embodiment, raw materials for KNbO ₃ and BaTiO ₃ are prepared. These preparations, for example, commercially available hydrothermal synthesis method, an oxalate method, a sol - may be used BaTiO ₃ powder produced using the gel method, or the like. Further, as the powder of KNbO _3, a powder produced using a solid phase synthesis method in which K ₂ CO ₃ and Nb ₂ O ₅ are used as raw materials and mixed, calcined, and pulverized may be used.

Next, a raw material for the accessory component is also prepared. In this embodiment, raw materials for MnCO ₃ and SiO ₂ are prepared. The raw material is not particularly limited, and oxides or composite oxides of the above-described components, or various compounds that become these oxides or composite oxides by firing, such as carbonates, nitrates, hydroxides, organometallic compounds, etc. Can be appropriately selected and used.

The dielectric ceramic composition of the present invention has the general formula (K, Ba) (Nb, Ti) by preparing KNbO ₃ powder and BaTiO ₃ powder in advance by the above-mentioned method and adjusting the firing conditions. Generation of a solid solution as represented by O ₁₂ can be controlled as little as possible.

  Moreover, when the dielectric ceramic composition according to the present embodiment contains the above-described subcomponent, a raw material for the subcomponent is also prepared. The raw material of the subcomponent is not particularly limited, and the above-described oxides and composite oxides of the respective components, or various compounds that become these oxides and composite oxides by firing, such as carbonates, nitrates, hydroxides, organics It can be appropriately selected from metal compounds and the like.

  The prepared raw materials are weighed and mixed so as to have a predetermined composition ratio to obtain a raw material mixture. Examples of the mixing method include wet mixing using a ball mill and dry mixing using a dry mixer.

  The obtained raw material mixture may be granulated by adding a binder resin, or may be granulated, or may be pasted together with a binder resin or a solvent to form a slurry. Moreover, you may calcine a raw material mixture before setting it as a granulated material or a slurry.

  The method for molding the granulated product or slurry is not particularly limited, and examples thereof include a sheet method, a printing method, dry molding, wet molding, and extrusion molding. In the present embodiment, dry molding is adopted, and the granulated product is filled in a mold and molded by compression and pressing (pressing). The shape of the molded body is not particularly limited, and may be appropriately determined according to the application. In the present embodiment, a disk-shaped molded body is used.

  The obtained molded body is baked after removing the binder as necessary.

  The firing conditions may be appropriately determined according to the composition and the like, but the firing temperature is preferably 900 to 1200 ° C., and the holding time is preferably 1 to 24 hours.

After firing, annealing is performed as necessary to obtain a dielectric ceramic composition as a sintered body. Although the annealing treatment is not necessarily performed in the present invention, the amount of solid solution of KNbO ₃ and BaTiO ₃ generated can be controlled by adjusting the annealing treatment conditions. Next, the obtained dielectric ceramic composition is subjected to end face polishing to form an electrode.

  The dielectric ceramic composition of the present embodiment produced as described above is suitably used for electronic parts such as ceramic capacitors. In the above description, the disk-shaped dielectric ceramic composition is exemplified as the dielectric ceramic composition according to the present embodiment. However, the dielectric ceramic that forms the dielectric layer of the multilayer electronic component by a sheet method or the like. It is good also as a composition.

  Further, the dielectric ceramic composition of the present embodiment also has good piezoelectric characteristics (for example, piezoelectric constant: d33 = 40 pC / N), and therefore is suitably used for piezoelectric elements.

  Furthermore, the dielectric ceramic composition according to the present invention may be used for an electronic component such as a single-plate capacitor or an electronic component such as a multilayer capacitor. Alternatively, it may be used for a piezoelectric element.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the embodiment mentioned above at all, and can be variously modified within the range which does not deviate from the summary of this invention.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples. In the following examples and comparative examples, various physical properties were evaluated as follows.

Dielectric constant εs
With respect to the capacitor sample, the capacitance C was measured at a reference temperature of 25 ° C. using a 4294A manufactured by Agilent Technologies, with a frequency of 1 kHz and a measurement voltage of 1 V. The relative dielectric constant εs (no unit) was calculated based on the thickness of the dielectric ceramic composition, the effective electrode area, and the capacitance C obtained as a result of the measurement. In this example, εs of 500 or more was considered good.

Capacitance temperature characteristics Capacitor sample is placed in a Despatch thermostat, capacitance at 1V is measured in the temperature range of -55 to 400 ° C, and capacitance at + 25 ° C (C25) The change rate (ΔC / C (%)) of the capacitance (dielectric constant) with respect to was calculated from the equation: ΔC / C = {(C−C25) / C25} × 100. In this example, the one having a capacitance change rate in the range of ± 22% was regarded as good (S characteristic).

Evaluation of first and second phase regions by image analysis The dielectric ceramic composition obtained by firing is micro-sampled using FIB (focused ion beam) to produce a TEM sample. did. This sample was subjected to STEM image observation using JEM2200FS and STEM-EDS mapping. The observation visual field was set to 3.0 μm × 3.0 μm, and five or more visual fields were observed for each sample. Using the composition maps obtained by these methods, the regions of K and Nb as the first phase elements and Ba and Ti as the second phase elements are specified, and the average of the results for each of five or more views Using the area, the ratio of a / b was calculated. In this example, in order to obtain a temperature characteristic of good capacity, the range was controlled in the range of 1.2 <a / b <5.7.

Example 1
First, KNbO ₃ having an average particle diameter of 500 nm, BaTiO ₃ having an average particle diameter of 200 nm, MnCO ₃ and SiO ₂ having an average particle diameter of 50 nm or less were prepared as starting materials. The prepared raw materials were weighed so as to have the values shown in Table 1, and wet-mixed for 17 hours with a ball mill together with water as a dispersion medium and an aqueous dispersant. And the mixture was dried and the raw material powder of the dielectric ceramic composition was obtained.

Experiment No. 1 shown in Table 1. 1 to 5 contain KNbO ₃ and BaTiO ₃ in a proportion of 70 mol% and 30 mol%, MnCO ₃ 0.5 mol% to 5.0 mol% and SiO ₂ 1.0 mol% as subcomponents This is a sample. Those marked with “*” are comparative examples. Experiment No. 6 ^* is a sample containing neither MnCO ₃ nor SiO ₂ . Furthermore, Experiment No. 7 ^* and 8 ^* show comparative examples with the present example to which MnCO ₃ was added.

  A disc-shaped green molded body having a diameter of 10 mm and a thickness of about 1 mm was obtained by adding 2% by weight of PVB as a binder resin to the obtained raw material powder and molding it at a pressure of 250 MPa. This was heated in the air at 700 ° C. for 10 hours for binder removal treatment.

Next, the obtained molded body after the binder removal was fired in air at 1100 to 1200 ° C. for 10 hours to obtain a disk-shaped sintered body. The obtained disk-shaped sintered body was further subjected to annealing treatment in order to adjust the amount of solid solution phase formed of KNbO ₃ and BaTiO ₃ . As annealing conditions, heat treatment was performed in air at 825 ° C. for 30 minutes. Further, the obtained sintered body was polished, an Ag electrode was applied to the main surface thereof, and a baking process was performed in air at 650 ° C. for 20 minutes to obtain a disk-shaped ceramic capacitor sample.

  The characteristics described above were evaluated for each sample. The results are shown in Table 2. In addition, numerical values expressed in italics in the table indicate numerical values that are outside the range of the target physical properties of the present invention.

As shown in Table 2, Experiment No. which contains neither MnCO ₃ nor SiO ₂ was used. 6 compared to ^* , the experiment No. within the scope of this example. 1 to 5 indicate a withstand voltage of 10 KV / mm or more. In addition, Experiment No. which is a comparative example. 7 ^* and 8 ^* have a withstand voltage of 10 KV / mm or less.

Example 2
First, KNbO ₃ having an average particle diameter of 500 nm, BaTiO ₃ having an average particle diameter of 200 nm, MnCO ₃ and SiO ₂ having an average particle diameter of 50 nm or less were prepared as starting materials. The prepared raw materials were each weighed so as to have the values shown in Table 3, and wet-mixed for 17 hours with a ball mill together with water as a dispersion medium and an aqueous dispersant. And the mixture was dried and the raw material powder of the dielectric ceramic composition was obtained.

Experiment No. shown in Table 3 Nos. 9 to 13 contain KNbO ₃ and BaTiO ₃ in 70 mol% and 30 mol% as main components, MnCO ₃ 2.5 mol% and SiO ₂ 0.2 mol% to 3.0 mol% as subcomponents. This is a sample. Note that those marked with “*” are comparative examples that are outside the scope of this embodiment. Experiment No. 14 ^* and 15 ^* indicate comparative examples with the present example to which SiO ₂ was added. The characteristics of the sample containing neither MnCO ₃ nor SiO ₂ are shown in Experiment No. 6 See ^* .

  A disc-shaped green molded body having a diameter of 10 mm and a thickness of about 1 mm was obtained by adding 2% by weight of PVB as a binder resin to the obtained raw material powder and molding it at a pressure of 250 MPa. This was heated in the air at 700 ° C. for 10 hours for binder removal treatment.

Next, the obtained molded body after the binder removal was fired in air at 1100 to 1200 ° C. for 10 hours to obtain a disk-shaped sintered body. The obtained disk-shaped sintered body was further subjected to annealing treatment in order to adjust the amount of solid solution phase formed of KNbO ₃ and BaTiO ₃ . As annealing conditions, heat treatment was performed in air at 825 ° C. for 30 minutes. Further, the obtained sintered body was polished, an Ag electrode was applied to the main surface thereof, and a baking process was performed in air at 650 ° C. for 20 minutes to obtain a disk-shaped ceramic capacitor sample.

  The characteristics described above were evaluated for each sample. The results are shown in Table 4. In addition, numerical values expressed in italics in the table indicate numerical values that are outside the range of the target physical properties of the present invention.

As shown in Table 4, Experiment No. containing neither MnCO ₃ nor SiO ₂ was used. 6 compared to ^* , the experiment No. within the scope of this example. 9 to 13 indicate a withstand voltage of 10 KV / mm or more. In addition, the content of SiO ₂ is less than 0.2 mol%, which is a comparative example of Experiment No. For 14 ^* , the withstand voltage is 10 KV / mm or less. More than 3.0 mol%, the experiment No. 15 ^* has a relative dielectric constant of less than 500 at 25 ° C.

Example 3
First, KNbO ₃ having an average particle diameter of 500 nm, BaTiO ₃ having an average particle diameter of 200 nm, MnCO ₃ and SiO ₂ having an average particle diameter of 50 nm or less were prepared as starting materials. The prepared raw materials were weighed so as to have the values shown in Table 5, and wet-mixed for 17 hours with a ball mill together with water as a dispersion medium and an aqueous dispersant. And the mixture was dried and the raw material powder of the dielectric ceramic composition was obtained.

Experiment No. shown in Table 5 Samples 16 to 18 are samples within the range of this example. 19 ^{* to} 20 ^* are comparative examples.

  A disc-shaped green molded body having a diameter of 10 mm and a thickness of about 1 mm was obtained by adding 2% by weight of PVB as a binder resin to the obtained raw material powder and molding it at a pressure of 250 MPa. This was heated in the air at 700 ° C. for 10 hours for binder removal treatment.

Next, the obtained molded body after the binder removal was fired in air at 1100 to 1200 ° C. for 10 hours to obtain a disk-shaped sintered body. The obtained disk-shaped sintered body was further subjected to annealing treatment in order to adjust the amount of solid solution phase formed of KNbO ₃ and BaTiO ₃ . As annealing conditions, heat treatment was performed in air at 825 ° C. for 30 minutes. Further, the obtained sintered body was polished, an Ag electrode was applied to the main surface thereof, and a baking process was performed in air at 650 ° C. for 20 minutes to obtain a disk-shaped ceramic capacitor sample.

  The characteristics described above were evaluated for each sample. The results are shown in Table 6. In addition, numerical values expressed in italics in the table indicate numerical values that are outside the range of the target physical properties of the present invention.

As shown in Table 6, the ratio of KNbO ₃ as the first phase and BaTiO ₃ as the second phase is within the range of 1.2 <a / b <5.7 within the range of this example. By doing so, it can be confirmed that the rate of change in capacitance can be controlled within ± 22%. Experiment No. which is a comparative example. 19 ^* does not satisfy the rate of change of capacitance within ± 22% in a temperature range of 200 ° C. or higher. Furthermore, Experiment No. which is a comparative example having a high ratio of the first phase. 20 ^* indicates that the rate of change in capacitance in a temperature region of 200 ° C. or higher does not satisfy ± 22% or less, and the withstand voltage is 10 KV / mm or less.

Example 4
First, as a starting powder, a part of K having an average particle diameter of 500 nm was substituted with Na (K _0.75 Na _0.25 ) NbO ₃ and a part of K was substituted with Li (K _0.75 Li _{0. 25} ) NbO ₃ , K (Nb _0.90 Ta _0.10 ) O _{3 in} which part of Nb is substituted with Ta, and BaTiO ₃ having an average particle diameter of 200 nm are prepared, and the mixing ratio shown in Table 7 is obtained. In addition, each was weighed and wet mixed with a ball mill for 17 hours using water as a dispersion medium. Thereafter, the obtained mixture was dried to obtain a raw material powder.

Next, KNbO ₃ having an average particle diameter of 500 nm as a starting powder and a part of Ba having an average particle diameter of 200 nm are replaced with Ca, Sr, Mg (Ba _0.75 Ca _0.25 ) TiO ₃ , (Ba _0.75 Sr _0.25 ) TiO ₃ , (Ba _0.75 Mg _0.25 ) TiO _3, and Ba (Ti _0.90 Zr _0.10 ) O in which a part of Ti is replaced with Zr, Co, Mo. ₃ , Ba (Ti _0.90 Co _0.10 ) O ₃ , Ba (Ti _0.90 Mo _0.10 ) O ₃ were prepared, weighed to achieve the combinations and blending ratios shown in Table 7, and dispersed. Wet mixing was performed for 17 hours by a ball mill using water as a medium. Thereafter, the obtained mixture was dried to obtain a raw material powder.

Experiment No. shown in Table 7 3 shows an embodiment in which no substitution is performed. Experiment No. 21 to 23 are examples in which K and Nb of KNbO ₃ were partially substituted. In addition, Experiment No. Examples 24 to 29 are examples in which Ba and Ti in BaTiO ₃ were partially substituted.

  A disc-shaped green molded body having a diameter of 10 mm and a thickness of about 1 mm was obtained by adding 2% by weight of PVB as a binder resin to the obtained raw material powder and molding it at a pressure of 250 MPa. This was heated in the air at 700 ° C. for 10 hours for binder removal treatment.

Next, the obtained molded body after the binder removal was fired in air at 1100 to 1200 ° C. for 10 hours to obtain a disk-shaped sintered body. The obtained disk-shaped sintered body was further subjected to annealing treatment in order to adjust the amount of solid solution phase formed of KNbO ₃ and BaTiO ₃ . As annealing conditions, heat treatment was performed in air at 825 ° C. for 30 minutes. Further, the obtained sintered body was polished, an Ag electrode was applied to the main surface thereof, and a baking process was performed in air at 650 ° C. for 20 minutes to obtain a disk-shaped ceramic capacitor sample.

  The characteristics described above were evaluated for each sample. The results are shown in Table 8.

As shown in Table 8, the experimental No. 3 with a partial substitution of K and Nb. 21-23, and experiment No. 1 in which Ba and Ti were partially substituted in BaTiO ₃ . It can be confirmed that the change rate of the electrostatic capacity can be controlled within ± 22% even at 24-29.

  Since the rate of change of relative permittivity is small and the withstand voltage is high in a wide temperature range, it is suitable for smoothing for power devices using SiC or GaN-based semiconductors in an environment close to the engine room for in-vehicle use. It can also be used as a capacitor.

Claims (2)

It has a main component composed of a mixed crystal of a first phase represented by the general formula KNbO ₃ and a second phase represented by the general formula BaTiO ₃ , and contains Mn and Si elements as subcomponents, It said first phase and when the main component 100 mol% consisting of the second phase, the content of the Mn is MnCO ₃ in terms of, 0.5 mol% or more, or less 5.0 mol%, the content of the Si is SiO The second phase represented by BaTiO _3, where a ratio of the first phase represented by KNbO ₃ is a and the ratio is 0.2 mol% or more and 3.0 mol% or less in terms of ₂ A dielectric ceramic composition characterized by satisfying a relationship of 1.2 <a / b <5.7, where b is a ratio of the total amount of the above. An electronic component having a dielectric and an electrode, wherein the dielectric is made of the dielectric ceramic composition according to claim 1 .