阅读说明：本技术 电介性无机组合物 (Dielectric inorganic composition ) 是由 傅杰 于 2020-03-23 设计创作，主要内容包括：提供一种电介质,其在-50℃至350℃的温度范围内的介电常数高,并且介电常数的变化率为30％以下。一种无机物质,其特征在于,其含有包含A与M的氧化物晶体(A为P、Ge和V的1种或2种以上,M为Nb和Ta的1种或2种以上),且介电常数为500以上。前述氧化物晶体为PNb-(9)O-(25)、P-(2.5)Nb-(18)O-(50)和GeNb-(9)O-(25)、GeNb-(18)O-(47)、GeNb-(19.144)O-(50)、VNb-(9)O-(25)、VNb-(9)O-(24.9)、PTa-(9)O-(25)、GeTa-(9)O-(25)、VTa-(9)O-(25)和它们的固溶体中的1种或2种以上。(Provided is a dielectric having a high dielectric constant in a temperature range of-50 ℃ to 350 ℃ and a rate of change in dielectric constant of 30% or less. AAn inorganic substance characterized by containing an oxide crystal comprising A and M (A is P, Ge and 1 or 2 or more of V, and M is 1 or 2 or more of Nb and Ta), and having a dielectric constant of 500 or more. The oxide crystal is PNb 9 O 25 、P 2.5 Nb 18 O 50 And GeNb 9 O 25 、GeNb 18 O 47 、GeNb 19.144 O 50 、VNb 9 O 25 、VNb 9 O 24.9 、PTa 9 O 25 、GeTa 9 O 25 、VTa 9 O 25 And 1 or 2 or more in solid solution thereof.)

1. An inorganic substance comprising an oxide crystal comprising A and M, wherein A is P, Ge and 1 or 2 or more of V, M is 1 or 2 or more of Nb and Ta, the ratio of A to M is in the range of 0.01 to 1.00, and the dielectric constant of the inorganic substance is 500 or more.

2. The inorganic substance according to claim 1, wherein the inorganic substance has a temperature change rate of a dielectric constant of 30% or less in a range of-50 ℃ to 350 ℃.

3. The inorganic substance of claim 1 or 2, wherein the oxide crystal is PNb₉O₂₅、P_2.5Nb₁₈O₅₀And GeNb₉O₂₅、GeNb₁₈O₄₇、GeNb_19.144O₅₀、VNb₉O₂₅、VNb₉O_24.9、PTa₉O₂₅、GeTa₉O₂₅、VTa₉O₂₅And 1 or more in solid solution thereofMore than 2 kinds.

4. A dielectric comprising the inorganic substance of any one of claims 1 to 3.

5. A dielectric according to claim 4, characterized in that it is ferroelectric.

6. A capacitor comprising the dielectric of claim 4 or 5.

Technical Field

The present invention relates to an inorganic composition having a property of being usable as a dielectric, and more particularly, to an inorganic composition having a high dielectric constant and a small rate of change of the dielectric constant in a region of-50 ℃ to 350 ℃, and a dielectric using the same.

Background

Along with the spread of electronic devices such as smart phones and flat panels, electronic components used in these electronic devices are required to be small-sized and high-performance, and laminated Ceramic capacitors (MLCCs) used as laminated capacitors are also required to be small-sized and large-capacitance.

In recent years, with the spread of electric vehicles, it has been required to directly mount an electronic mounting board on a motor peripheral portion which is at a high temperature for the purpose of enhancing motor performance and making the motor compact, and with the increase in the temperature of the use environment of in-vehicle electronic components, it has been similarly required for MLCCs that the capacitance is high even at a higher temperature (200 ℃ to 350 ℃) and the capacitance temperature characteristic is good. That is, the dielectric constant of the dielectric constituting the capacitor is required to be high even in a high temperature region exceeding 200 ℃, and the variation of the dielectric constant with respect to temperature is also required to be small.

In recent years, there has been an increasing demand for capacitors having a high energy storage density, which are used in excimer lasers, medical X-rays, power storage devices, power transmission equipment, and the like, which are used in semiconductor processing and vision correction surgery. In order to obtain an energy storage density for a dielectric used for such a capacitor, it is required to have both a high dielectric constant and a high dielectric breakdown strength, and also to have a small temperature change of the capacitance at a high temperature.

However, BaTiO commonly used as dielectrics₃Since the Curie temperature is around 130 ℃, the dielectric constant is greatly lowered in a temperature region of 150 ℃ or higher, and there is a problem that the above requirements cannot be satisfied.

Patent document 1 describes that BaTiO can be improved₃The Curie temperature of the composite material of (A) is up to 200 ℃ and a good temperature characteristic of capacitance can be obtained, but the dielectric constant of the material is below 500, and a large capacitance cannot be obtained.

In addition, as a dielectric material having good temperature characteristics of capacitance, KNbO was studied₃、K_0.5Na_0.5NbO₃And the like. However, potassium (K) is scattered (sublimated) during the firing of the dielectric materials, and the obtained dielectric materials have a problem of a decrease in insulation properties due to generation of lattice defects. Here, since dielectric breakdown is likely to occur when the dielectric material is made semiconductive when the insulation property is lowered, there is a problem that the reliability of the ceramic electronic component is lowered when the dielectric material is applied to a ceramic electronic component such as a capacitor. Further, the scattering of potassium (K) makes it difficult to control the production process, and this may result in a reduction in productivity.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-119607.

Disclosure of Invention

Problems to be solved by the invention

The present invention aims to solve the above problems. That is, an object of the present invention is to provide a dielectric having a high dielectric constant and stable temperature dependence up to a high temperature region.

Means for solving the problems

The present inventors have made diligent studies to solve the above problems and, as a result, have found that: the present invention has been completed by finding that in an oxide crystal containing a and M (a is P, Ge and 1 or 2 or more types of V, and M is 1 or 2 or more types of Nb and Ta), the ratio of a to M is in the range of 0.01 to 1.00, whereby the dielectric constant is 500 or more.

The present invention is the following (1) to (6).

(1) An inorganic substance comprising an oxide crystal comprising A and M, wherein A is P, Ge and 1 or 2 or more of V, M is 1 or 2 or more of Nb and Ta, the ratio of A to M is in the range of 0.01 to 1.00, and the dielectric constant of the inorganic substance is 500 or more.

(2) The inorganic substance according to the above (1), characterized in that it has a temperature change rate of dielectric constant of 30% or less in a range of-50 ℃ to 350 ℃.

(3) The inorganic substance according to the above (1) or (2), wherein the oxide crystal is PNb₉O₂₅、P_2.5Nb₁₈O₅₀And GeNb₉O₂₅、GeNb₁₈O₄₇、GeNb_19.144O₅₀、VNb₉O₂₅、VNb₉O_24.9、PTa₉O₂₅、GeTa₉O₂₅、VTa₉O₂₅And 1 or 2 or more in solid solution thereof.

(4) A dielectric comprising the inorganic substance described in any one of (1) to (3).

(5) The dielectric according to the above (4), which is a ferroelectric.

(6) A capacitor comprising the dielectric according to (4) or (5) above.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a dielectric having a high dielectric constant and excellent temperature characteristics in a temperature range of-50 ℃ to 350 ℃ and a ceramic capacitor including the dielectric can be provided.

Drawings

Fig. 1 is a diagram showing XRD patterns of example 1 and example 2.

Fig. 2 is a graph showing the dielectric constant versus frequency for examples 1 and 2.

Fig. 3 is a graph showing the relationship between the dielectric constant and the temperature of example 4.

Fig. 4 is a graph showing a hysteresis curve of example 4.

Fig. 5 is a graph showing the dielectric constant versus frequency of example 5.

Fig. 6 is a graph showing the relationship between the dielectric constant and the temperature of example 5.

Fig. 7 is a graph showing the dielectric constant versus frequency of example 6.

Fig. 8 is a graph showing the relationship between the dielectric constant and the temperature of example 6.

Detailed Description

Dielectric of the invention

The inorganic composition of the present invention is described.

The inorganic composition of the present invention is useful as a dielectric and is a ceramic containing oxide crystals of A and M (A is P, Ge and 1 or 2 or more of V, and M is 1 or 2 or more of Nb and Ta). By adjusting the ratio of A to M, the dielectric constant can be adjusted to 500 or more, and the dielectric constant can be adjusted to a small extent over a wide temperature range of-50 ℃ to 350 ℃. In order to obtain excellent dielectric characteristics, the ratio of a to M is preferably in the range of 0.01 to 1.00, more preferably in the range of 0.03 to 0.50, and most preferably in the range of 0.04 to 0.20. Among the aforementioned oxide crystals comprising A and M, PNb is particularly preferred₉O₂₅、P_2.5Nb₁₈O₅₀And GeNb₉O₂₅、GeNb₁₈O₄₇、GeNb_19.144O₅₀、VNb₉O₂₅、VNb₉O_24.9、PTa₉O₂₅、GeTa₉O₂₅、VTa₉O₂₅And their solid solutions have more excellent characteristics, so that they are preferably contained.

The inorganic composition of the present invention may contain other components than those described above, for example, SiO₂、GeO₂、B₂O₃、Al₂O₃、ZnO、Bi₂O₃、TiO₂、ZrO₂、V₂O₅、Ta₂O₅、WO₃Alkali metal oxides, alkaline earth metal oxides, rare earth oxides, transition metal oxides, and the like. These components may function as a sintering aid, may be present alone, may be dissolved in the crystal, or may form a new crystal together with the element constituting the crystal. By introducing these sintering aids, the firing temperature is lowered or a solid solution is formed, whereby the dielectric characteristics can be improved.

Glass may be added to the inorganic composition of the present invention. The glass acts as a sintering aid and has the effect of lowering the firing temperature.

The inorganic composition of the present invention may be combined with other dielectric crystals, such as tungsten bronze type crystals, perovskite type crystals, CaZrO₃Crystal, SrZrO₃Crystal, BaTi₂O₅Crystal, CaTi₂O₅Crystals, etc. are combined. By making a complex with these dielectrics, the dielectric characteristics as designed can be approximated. The tungsten bronze crystal preferably contains MNb₂O₆(M：Ca、Sr、Ba)、M₂RNb₅O₁₅(M：Ca、Sr、Ba；R：Na、K)、K₂LnNb₅O₁₅(Ln: Y, Ce, Sm, Eu, La, Gd, Tb, Dy, Ho, Bi) crystal and solid solution thereof. The perovskite crystal particularly preferably contains a compound selected from the group consisting of RNbO₃、RTaO₃、(Bi_0.5、R_0.5)TiO₃(R：Na、K)、MTiO₃(M: Ca, Sr, Ba) crystals and solid solutions thereof.

The inorganic composition of the present invention has a dielectric constant of preferably 500 or more, more preferably 650 or more, particularly preferably 800 or more, and most preferably 900 or more at a frequency of 1kHz to 100 kHz.

The inorganic composition of the present invention has a temperature change rate of dielectric constant at 1kHz or/and 100kHz of preferably 30% or less in a temperature range of-50 ℃ to 350 ℃, more preferably 20% or less, particularly preferably 15% or less, and most preferably 10% or less in a temperature range of-50 ℃ to 350 ℃.

In the present invention, the dielectric constant and the dielectric loss are measured at a frequency of 100Hz to 1MHz by using an LRC tester (Keysight Technology, 4274A) or an impedance analyzer (for example, SI1260 manufactured by Solartron corporation), and the value at 1kHz or 100kHz is regarded as the dielectric constant and the dielectric loss of the present invention.

When the inorganic composition of the present invention is a dielectric ceramic, it has a high relative dielectric constant and is excellent in temperature characteristics over a wide temperature range of-50 ℃ to 350 ℃. And thus can be suitably used as a capacitor against high temperatures. Specifically, there may be mentioned: an electronic component used for the operation of a power element based on SiC or GaN, which is an in-vehicle element intended as an electronic component used in a high-temperature environment, the removal of noise in an automobile engine room, or the like.

The dielectric material using the inorganic composition of the present invention is ferroelectric and can be expected to have good piezoelectric properties (for example, piezoelectric constant: d, electromechanical coupling coefficient: k), and therefore, it can be suitably used for a piezoelectric element.

< manufacturing method >

The method for producing the inorganic composition of the present invention will be described.

First, raw materials for the respective components constituting the inorganic composition of the present invention are prepared. The raw materials for the respective components are not particularly limited, and can be suitably selected and used from various oxides, composite oxides, and various compounds (for example, carbonates, nitrates, hydroxides, fluorides, organic metal compounds, and the like) which can be formed into oxides or composite oxides of the above-described components by firing.

Next, the prepared raw materials were weighed so as to have a predetermined composition ratio and mixed 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 to the raw material mixture to obtain a granulated product, or may be formed into a paste together with a binder resin or a solvent to form a slurry. Alternatively, the raw material mixture may be calcined before being formed into a granulated substance or slurry.

The method of forming the granulated substance or slurry is not particularly limited, and examples thereof include: sheet method, printing method, dry molding, wet molding, extrusion molding, and the like. For example, in the case of dry molding, the pellets are filled in a mold and compressed (pressed) to be molded. The shape of the molded article is not particularly limited, and may be determined as appropriate depending on the application.

The obtained molded body is fired by any of methods such as atmospheric pressure sintering, hot press sintering, hot isostatic pressing (hot isostatic pressing) pressure sintering, spark plasma sintering, and microwave sintering, if necessary, to obtain a ceramic dielectric. The firing conditions may be determined as appropriate depending on the firing method, composition, etc., and the firing temperature is preferably 800 ℃ to 1400 ℃, and the holding time is preferably several minutes to 24 hours.

The ceramic dielectric after firing may be heat-treated in the atmosphere, oxygen, or a reducing atmosphere, if necessary. By such heat treatment, defects are reduced and dielectric characteristics of the dielectric are improved. Preferably, the heat treatment temperature is in the range of 700 ℃ to 1200 ℃ and the treatment time is in the range of 1 hour to 24 hours.

The ceramic dielectric composed of the inorganic composition of the present invention produced in this manner can be suitably used for electronic parts such as capacitors.

Although the method for producing a ceramic dielectric composed of the inorganic composition of the present invention in a disk shape has been described above, a ceramic capacitor constituting a dielectric layer of a laminated electronic component can be similarly produced by a green compact method or the like. That is, the dielectric powder of the present invention is made into a paste, a dielectric green layer is formed on a carrier film (carrier film) by a doctor blade method or the like, and an internal electrode layer paste is printed thereon in a predetermined pattern, then, they are peeled 1 layer by layer, laminated, and integrally molded by applying pressure, and finally fired at a temperature of about 800 ℃ to 1200 ℃, thereby manufacturing a ceramic capacitor.

The inorganic composition of the present invention can be used to produce a thin film dielectric by a general thin film formation method. For example, a thin film dielectric can be formed by a vacuum Deposition method, a high-frequency sputtering method, a Pulsed Laser Deposition (PLD), an MOCVD (Metal Organic Chemical Vapor Deposition) method, an MOD (Metal Organic Deposition) method, a gel-sol method, a hydrothermal method, or the like.

Therefore, the inorganic composition of the present invention can be used for electronic parts such as a single-plate capacitor, electronic parts such as a laminated capacitor, and electronic parts in a film form. Or may be used for piezoelectric elements.

Examples

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto at all.

< preparation of examples 1 to 4 >

The inorganic composition containing oxide crystals containing P and Nb was produced by spark plasma sintering in the following order. First, NH to be used as a raw material₄H₂PO₄And Nb₂O₅The powder of (2) was mixed at a predetermined ratio (P/Nb ═ 0.11), filled in a polyethylene bowl together with zirconia balls having a diameter of 2mm and ethanol, mixed for 24 hours, and then dried for 24 hours. The dried mixed powder was preburnt at 1000 ℃ for 2 hours. The obtained calcined product was mixed, pulverized and dried under the same conditions as described above to obtain a dielectric powder composed of an inorganic composition. 4g of the dielectric powder was filled in a graphite mold having an inner diameter of 20mm, and a pressure of 35MPa was applied in the vertical direction in a vacuum atmosphere by a discharge plasma sintering apparatus (Sumitomo rock and coal mining Co., Ltd., SPS625), and the resultant was held at 1050 ℃ to 1200 ℃ for 5 minutes to 12 minutes, thereby obtaining a disk-shaped dielectric. The obtained disk-shaped dielectric material was polished on both sides and then heat-treated at 1000 ℃ for 4 hours while flowing oxygen at 1L/min, to obtain a sample for evaluating physical properties. Table 1 shows the production conditions and physical properties of the examples.

The XRD patterns of example 1 and example 2 are shown in fig. 1. All diffraction peaks are attributed to PNb₉O₂₅It is known that the ceramic dielectric is formed of PNb₉O₂₅Formed of crystals. The XRD pattern was measured using an X-ray diffraction device (product name: X' Pert-MPD, manufactured by Philips).

Fig. 2 shows the frequency dependence of the dielectric constant of example 1 and example 2. The dielectric constant and dielectric loss were measured by depositing gold electrodes on both surfaces of the sample and using an impedance analyzer (SI 1260, manufactured by Solartron corporation) at room temperature (25 ℃). From this figure, the measured frequency range (100Hz to 10 Hz)⁶Hz), the dielectric constant is 900 or more, and does not change greatly depending on the frequency. Further, as a result of confirming the dielectric loss, it was found that the dielectric loss was as small as 5% or less in the above frequency range.

The temperature dependence of the dielectric properties was determined using an LCR tester at a temperature range of-30 ℃ to 350 ℃ across a frequency of 100Hz to 100 kHz. Fig. 3 shows the measurement results for example 4 as a representative example. Which is the result of a dielectric constant versus temperature plot at a frequency of 100 kHz. From this figure, it can be seen that the dielectric constant of the dielectric of the present invention shows a high value, but does not change greatly in the temperature range of-30 ℃ to 350 ℃.

Rate of change of dielectric constant with temperature (. epsilon.)_T) The dielectric constant was calculated from the following equation by determining how much the dielectric constant changed at each temperature based on the dielectric constant at 25 ℃.

ε_T(%) (% dielectric constant at target temperature-dielectric constant at 25 ℃) and dielectric constant at 25 ℃]×100％

The rate of change (. epsilon.) of dielectric constant of example 4, determined from the above equation_T) Shown in fig. 3. From these results, it was found that the rate of change of the dielectric constant was 25% or less in the temperature range of-30 ℃ to 350 ℃ and 10% or less in the temperature range of-30 ℃ to 250 ℃.

[ Table 1]

Fig. 4 shows the electric field-polarization curve of example 4. From this figure, the present dielectric is ferroelectric.

< preparation of example 5 >

The inorganic composition containing oxide crystals containing Ge and Nb was produced by a discharge plasma sintering method in the following order. First, GeO as a raw material₂And Nb₂O₅The powder of (2) was mixed at a predetermined ratio (Ge/Nb ═ 0.11), filled in a polyethylene bowl together with zirconia balls having a diameter of 2mm and ethanol, mixed for 24 hours, and then dried for 24 hours. The dried mixed powder was preburnt at 950 ℃ for 2 hours. The obtained calcined product was mixed, pulverized and dried under the same conditions as described above to obtain a dielectric powder composed of an inorganic composition. 2.5g of the dielectric powder was charged in a graphite mold having an inner diameter of 15mm, and the resultant was heated at 900 ℃ for 5 minutes while applying a pressure of 50MPa in the vertical direction in a vacuum atmosphere by a spark plasma sintering apparatus, thereby obtaining a disk-shaped dielectric. The resulting disk-shaped dielectric material was polished on both sides and then heat-treated at 850 ℃ for 4 hours while passing oxygen at a flow rate of 2L/min to obtain a sample for evaluating physical properties.

GeNb is presumed to be generated by the analysis of XRD pattern_19.144O₅₀Crystalline phase or GeNb₉O₂₅A crystalline phase. Due to GeNb_19.144O₅₀And GeNb₉O₂₅Since the diffraction peaks of (2) are overlapped, 2 crystals may coexist at the same time.

Fig. 5 shows the frequency dependence of the dielectric constant of example 5. It is known that the dielectric constant is as high as 4000 to 5000 in the measured frequency range. From the relationship between the dielectric characteristics and the temperature characteristics in FIG. 6, it was confirmed that the change in the dielectric constant was small and the rate of change in the dielectric constant was 15% or less at a high temperature of 250 ℃ or higher.

< preparation of example 6 >

The inorganic composition containing an oxide crystal containing Ge and Nb is produced by a general sintering method in the following order. First, GeO as a raw material₂And Nb₂O₅The powder of (2) was mixed at a predetermined ratio (Ge/Nb 0.11), and the mixture was packed in a poly (ethylene glycol) together with zirconia balls having a diameter of 2mm and ethanolThe mixture was mixed in a vinyl pot for 24 hours, and then dried for 24 hours. The dried mixed powder was preburnt at 950 ℃ for 2 hours. The obtained calcined product was mixed, pulverized and dried under the same conditions as described above to obtain a dielectric powder composed of an inorganic composition. 2.0g of the dielectric powder was charged in a mold having an inner diameter of 20mm, and the dielectric powder was biaxially pressed and molded into pellets, which were then sintered at 1170 ℃ for 4 hours in an electric furnace in the air. The obtained disk-shaped dielectric was measured for dielectric constant after XRD measurement.

Since the XRD pattern was the same as that of example 5, it was found to have the same crystal phase.

Fig. 7 shows the frequency dependence of the dielectric constant of example 6. It was found that the dielectric constant was approximately maintained at about 700 in the measured frequency range. From the relationship between the dielectric characteristics and the temperature characteristics in FIG. 8, it was confirmed that the rate of change of the dielectric constant was as low as 15% or less and the dielectric loss was 0.5 or less when the temperature was increased to 200 ℃ or higher.