JP7657019B2 - Dielectric powder and method for producing the same - Google Patents

Description

The present invention relates to a dielectric powder and a method for producing the same .

Electronic components such as multilayer ceramic capacitors are known to be manufactured using dielectric powder. In recent years, electronic components have become increasingly smaller, and as a result, there is a demand for the dielectric powder used in manufacturing electronic components to also become smaller.

JP 2017-178686 A

However, the heat applied during the manufacturing process causes grain growth in dielectric powder, making it difficult to further miniaturize it.

The present invention is devised to solve the above-mentioned problems, and has an object to provide a dielectric powder that can be atomized by suppressing grain growth when heated , and a method for producing such a dielectric powder .

The dielectric powder of the present invention contains a perovskite type compound containing at least Ca and Zr, and a compound containing P,
The specific surface area is 5 m2 ^/ g or more and 40 ^m2 /g or less, and the primary particle size is 33 nm or more and 260 nm or less,
The P content is in the range of 0.01 to 10 parts by mol relative to 100 parts by mol of the Zr .

The compound containing P may be a phosphate compound.

The method for producing a dielectric powder of the present invention is a method for producing a dielectric powder containing at least a perovskite type compound containing Ca and Zr, and a compound containing P, and is characterized in that it includes a step of heat - treating a mixture of the Ca compound containing Ca, the Zr compound containing Zr, and the compound containing P at a temperature of 700°C or higher and 1500°C or lower.
The dielectric powder may have a specific surface area of 5 ^m2 /g or more and 40 ^m2 /g or less and a primary particle size of 33 nm or more and 260 nm or less, and the P may be contained in an amount of 0.01 molar parts or more and 10 molar parts or less relative to 100 molar parts of the Zr.
The method may also include a step of pulverizing the mixture after the heat treatment.

The present invention provides a dielectric powder that can be atomized by suppressing grain growth during heating.

The following describes an embodiment of the present invention and explains its features in detail.

The dielectric powder of the present invention satisfies the following requirements (hereinafter referred to as the requirements of the present invention), that is, it contains a perovskite type compound containing at least Ca and Zr and a compound containing P , has a specific surface area of 5 m2 ^/ g to 40 ^m2 /g, a primary particle diameter of 33 nm to 260 nm, and P is contained in an amount of 0.01 molar parts to 10 molar parts per 100 molar parts of Zr . The perovskite type compound containing at least Ca and Zr is, for example, _CaZrO3 . By containing the compound containing P in the dielectric powder, grain growth due to heating can be suppressed.

In the dielectric powder of the present invention, the specific surface area is 5 ^m2 /g or more and 40 ^m2 /g or less, and the primary particle size is 33 nm or more and 260 nm or less . When the particles are made finer, the crystallinity of the particles may decrease, but as described later, by setting the specific surface area to 40 ^m2 /g or less, the decrease in crystallinity can be suppressed.

The above-mentioned dielectric powder can be produced, for example, using a Ca compound having a primary particle diameter of 20 nm or more and 150 nm or less, a Zr compound having a primary particle diameter of 2 nm or more and 50 nm or less, and a compound containing P.

The Ca compound is a compound containing Ca, for example, at least one of calcium carbonate and calcium hydroxide. The Zr compound is a compound containing Zr, for example, at least one of zirconium oxide and zirconium hydroxide. The P compound is, for example, a phosphate compound.

The dielectric powder of the present invention can be produced by heat treating a mixture of the Ca-containing Ca compound, the Zr-containing Zr compound, and the P-containing compound at a temperature of 700°C to 1500°C, and then pulverizing the mixture after the heat treatment.

The dielectric powder of the present invention can be used to manufacture electronic components such as multilayer ceramic capacitors.

<Example>
First, prepared were a Ca compound having a primary particle size of 20 nm or more and 150 nm or less and a specific surface area of 7 ^m2 /g or more and 60 ^m2 /g or less, a Zr compound having a primary particle size of 2 nm or more and 50 nm or less and a specific surface area of 10 ^m2 /g or more and 200 ^m2 /g or less, and a compound containing P. Here, calcium carbonate was prepared as the Ca compound, and zirconium oxide was prepared as the Zr compound.

Then, the prepared Ca compound and Zr compound were put into a solvent and dissolved to prepare a slurry. Pure water was used as the solvent. The molar ratio of the Ca compound and Zr compound put into the solvent (Ca compound/Zr compound) is preferably 0.980 or more and 1.025 or less, and more preferably 0.993 or more and 1.014 or less.

Then, a compound containing P was added to the prepared slurry and mixed in a ball mill, then pulverized in a bead mill and dried at a temperature of 70°C to 300°C while stirring. The compound containing P is a phosphate compound, and ammonium hydrogen phosphate was used here. However, the phosphate compound is not limited to ammonium hydrogen phosphate, and sodium phosphate, calcium phosphate, etc. can also be used.

The product was then sieved and heat-treated, specifically, fired at a temperature between 700°C and 1500°C. If the firing temperature was less than 700°C, synthesis was insufficient, and if it was higher than 1500°C, grain growth was difficult to suppress.

The sintered product was then mixed with an aqueous solution to form a slurry, which was then pulverized in a bead mill to obtain a dielectric powder. In this dielectric powder, P is contained in an amount of 0.001 to 10 parts by mole per 100 parts by mole of Zr. If the P content is less than 0.001 parts by mole per 100 parts by mole of Zr, it is difficult to obtain the effect of suppressing grain growth during sintering, and if it is more than 10 parts by mole, the crystallinity deteriorates and, since too much P is added, the zirconia and calcium do not come into contact with each other, making it difficult to obtain calcium zirconate. Therefore, it becomes meaningless as a material for ceramic capacitors.

Here, we will provide more detailed numerical values for the method of producing the dielectric powder of sample number 2. First, Ca compounds and Zr compounds were put into a solvent and dissolved to produce a slurry. Pure water was used as the solvent. The molar ratio of Ca compounds to Zr compounds (Ca compounds/Zr compounds) put into the solvent was 1.000. A compound containing P was added to the produced slurry and mixed in a ball mill, then crushed in a bead mill and dried at a temperature of 100°C while stirring. The compound containing P was a phosphate compound, and ammonium hydrogen phosphate was used here. The product was sieved and then fired at a temperature of 1000°C, and the fired product was mixed with an aqueous solution to produce a slurry, and then crushed in a bead mill to obtain a dielectric powder.

Here, several kinds of dielectric powders with different amounts of P added were prepared, and the specific surface area and the half width of the second peak of CaZrO ₃ by X-ray diffraction were measured. The specific surface area can be measured, for example, by the flow method or the BET one-point method. The lower the value of the half width of the second peak of CaZrO ₃ by X-ray diffraction, the higher the crystallinity. The specific surface area, the average value of the primary particle size, the half width of the second peak of CaZrO ₃ by X-ray diffraction, and the amount of P added of the prepared dielectric powders of sample numbers 1 to 15 are shown in Table 1. The amount of P added is the molar amount relative to 100 molar parts of Zr.

In Table 1, the dielectric powders of sample numbers 2 to 14 , which are not marked with an *, satisfy the requirements of the present invention, and the dielectric powders of sample numbers 1 and 15 , which are marked with an *, do not satisfy the requirements of the present invention.

The dielectric powder of sample number 1, which does not contain P and does not meet the requirements of the present invention, undergoes grain growth during firing, resulting in coarsening of the crystal grains.

In contrast, the dielectric powders of sample numbers 2 to 14 , which contain a compound containing P and satisfy the requirements of the present invention, are suppressed in grain growth during firing. Therefore, when an electronic component such as a multilayer ceramic capacitor is manufactured using a dielectric powder satisfying the requirements of the present invention, the dielectric layer can be made thinner, and an electronic component with excellent characteristics can be manufactured.

Furthermore, the dielectric powders of sample numbers 2 to 14 which satisfy the requirements of the present invention have a half-width of the second peak of CaZrO ₃ measured by X-ray diffraction of less than 1.0, and are highly crystalline .

On the other hand, as shown in Table 1, the dielectric powder of sample number 15 having a specific surface area of more than 40 m ² /g has a half-width of the second peak of CaZrO ₃ in X-ray diffraction of more than 1.0 and has low crystallinity.

The present invention is not limited to the above embodiment, and various applications and modifications are possible within the scope of the present invention.

Claims (4)

A perovskite-type compound containing at least Ca and Zr, and a compound containing P,
The specific surface area is 5 ^m2 /g or more and 40 ^m2 /g or less, and the primary particle size is 33 nm or more and 260 nm or less,
The P is contained in an amount of 0.01 to 10 parts by mol relative to 100 parts by mol of the Zr,
The dielectric powder, wherein the compound containing P is derived from a phosphate compound. A method for producing a dielectric powder containing a perovskite type compound containing at least Ca and Zr and a compound containing P, comprising:
The method includes a step of heat-treating a mixture of the Ca compound containing Ca, the Zr compound containing Zr, and a phosphate compound at a temperature of 700° C. or more and 1500° C. or less;
The method for producing a dielectric powder, wherein the compound containing P is derived from a phosphate compound. 3. The method for producing a dielectric powder according to claim 2, characterized in that the dielectric powder has a specific surface area of 5 ^m2 /g or more and 40 ^m2 /g or less and a primary particle diameter of 33 nm or more and 260 nm or less, and the P is contained in an amount of 0.01 molar parts or more and 10 molar parts or less relative to 100 molar parts of the Zr. The method for producing a dielectric powder according to claim 2 or 3, further comprising a step of pulverizing the mixture after the heat treatment.