CN111017978A

CN111017978A - Preparation method of nano holmium oxide for dielectric ceramic capacitor

Info

Publication number: CN111017978A
Application number: CN201911373285.2A
Authority: CN
Inventors: 戴连欣; 刘卫华; 秦庆新; 黄雍
Original assignee: Jiangxi Xintai Functional Materials Technology Co Ltd
Current assignee: Jiangxi Xintai Functional Materials Technology Co Ltd
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2020-04-17

Abstract

The invention discloses a preparation method of nano holmium oxide for a dielectric ceramic capacitor, aiming at solving the problems of large particle size and poor dispersion performance of the existing rare earth oxide. The method comprises the following specific steps: preparing a holmium salt solution and an alkaline precipitator solution; step two, stirring and heating a holmium salt solution to 30-100 ℃, slowly dropping an alkaline precipitator solution into the holmium salt solution, and controlling the final pH value of the solution after precipitation to be 4.5-9.0; thirdly, aging the precipitate precursor; filtering and washing the aged precipitate precursor; and step five, drying, roasting, crushing and screening the washed precipitate precursor to obtain a finished product. The nano rare earth oxide finished product obtained by the invention can reach the nano size, is easy to disperse, and is particularly suitable for producing miniaturized or miniaturized dielectric ceramic capacitors.

Description

Preparation method of nano holmium oxide for dielectric ceramic capacitor

Technical Field

The invention relates to the field of dielectric ceramic capacitors, in particular to a preparation method of nano holmium oxide for a miniaturized or miniaturized dielectric ceramic capacitor.

Background

The ceramic material is an indispensable material in human life and modern construction, the excellent performance of the ceramic material is unique in the material field and is highly valued by people, and the dielectric ceramic as one of electronic ceramics plays a vital role in miniaturization and the production of portable electronic products.

The dielectric ceramic is also called dielectric ceramic, and is functional ceramic which has polarization capability under the action of an electric field and can establish the electric field in a body for a long time. And may be classified into electrical insulation, capacitors, piezoelectric, pyroelectric, and ferroelectric ceramics according to the use and properties. The insulating material has the characteristics of high insulating resistivity, small dielectric constant, small dielectric loss, good heat conducting property, small expansion coefficient, good thermal stability and chemical stability and the like. In order to meet the requirements of miniaturization and miniaturization of various electronic products, the volume of the dielectric ceramic multilayer capacitor is smaller and smaller, and the thickness of the dielectric layer is only about 1 micron. In order to prepare the dielectric layer material, the particle size of barium-titanium powder is controlled, and more strict requirements are provided for the particle size and the dispersion property of additives, such as rare earth oxide, uniformly covered on the surfaces of the barium-titanium powder particles. The particle size of the existing rare earth oxide is generally 3-5 microns, and the existing rare earth oxide is difficult to grind to be within 100 nanometers by physical means, which brings a bottleneck for the miniaturization and microminiaturization production of dielectric ceramics.

Disclosure of Invention

An object of an embodiment of the present invention is to provide a method for preparing nano holmium oxide for a dielectric ceramic capacitor, so as to solve the problems in the background art.

In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

a preparation method of nano holmium oxide for a dielectric ceramic capacitor comprises the following specific steps:

preparing a holmium salt solution and an alkaline precipitator solution, wherein the concentration of holmium oxide in the holmium salt solution is 30-400g-REO/L, the concentration of free acid in the holmium salt solution is 0.05-2.0mol/L, the concentration of hydroxyl in the alkaline precipitator solution is 0.1-10mol/L, and g-REO/L is the weight (g, g) of oxide (REO) in unit volume (L);

step two, stirring and heating a holmium salt solution to 30-100 ℃, preferably 40-90 ℃, more preferably 45-80 ℃, slowly dripping an alkaline precipitator solution into the holmium salt solution, and controlling the final pH value of the solution after precipitation to be 4.5-9.0;

step three, carrying out aging treatment on the precipitate precursor, wherein the temperature of the aging treatment is 45-150 ℃, preferably 50-120 ℃, more preferably 60-100 ℃, and the time of the aging treatment is 0.25-15h, preferably 0.5-10h, more preferably 1-7 h;

filtering and washing the aged precipitate precursor at the washing temperature of 40-80 ℃, wherein the conductivity of the filtered filtrate is less than 1 mu s/cm;

and step five, drying, roasting, crushing and screening the washed precipitate precursor to obtain a finished product. The method can also adopt the method that holmium salt solution is slowly dripped into alkaline precipitator solution or holmium salt solution and alkaline precipitator solution are simultaneously added into primer solution to generate precipitate precursor, wherein the primer solution can be pure water or aqueous solution containing holmium salt solution.

As a further scheme of the embodiment of the invention: the holmium salt solution in the first step comprises at least one of a holmium chloride solution, a holmium sulfate solution and a holmium nitrate solution.

As a further scheme of the embodiment of the invention: the alkaline precipitant solution in the first step comprises one or more of sodium hydroxide solution, potassium hydroxide solution, ammonia water solution, sodium carbonate solution, sodium bicarbonate solution, ammonium carbonate solution and ammonium bicarbonate solution.

As a further scheme of the embodiment of the invention: and in the second step, the time for dropping the alkaline precipitant solution into the holmium salt solution is 0.25-8 h.

As a further scheme of the embodiment of the invention: in the fifth step, the roasting temperature is 500-950 ℃, preferably 550-850 ℃, and the roasting time is 2-20h, preferably 5-15 h.

As a further scheme of the embodiment of the invention: the concentration of holmium oxide in the holmium salt solution is 40-300 g-REO/L.

As a further scheme of the embodiment of the invention: the concentration of holmium oxide in the holmium salt solution is 50-200 g-REO/L.

As a further scheme of the embodiment of the invention: the concentration of hydroxide radical in the alkaline precipitant solution is 0.3-5 mol/L.

As a further scheme of the embodiment of the invention: the concentration of hydroxide radical in the alkaline precipitant solution is 0.5-3 mol/L.

Compared with the prior art, the embodiment of the invention has the beneficial effects that:

the invention has reasonable design, the obtained finished product can reach the nanometer size, is easy to disperse, is particularly suitable for the production of dielectric ceramic capacitors, and has wide application prospect.

Drawings

FIG. 1 is a flow chart of a preparation method of nano holmium oxide for dielectric ceramic capacitors.

Fig. 2 is a scanning electron microscope image of a finished product in the preparation method of nano holmium oxide for a dielectric ceramic capacitor.

Detailed Description

The technical solution of the present patent will be described in further detail with reference to the following embodiments.

Example 1

In a 2L three-necked flask, 0.5L of holmium chloride (HoCl) was added₃) Solution of holmium oxide (Ho)₂O₃) The conversion concentration is 50g/L, the concentration of free acid is 0.1mol/L, and the mixture is stirred and heated to 50 ℃;

precipitant sodium carbonate (Na) at room temperature₂CO₃) Slowly dripping the solution into the holmium chloride solution with the concentration of 0.5mol/L for 1h, and controlling the final pH value of the solution after precipitation to be between 6.0 and 6.5;

aging treatment is carried out after precipitation, the aging temperature is 50 ℃, and the aging time is 1 h;

filtering the aged slurry, and washing with warm water at 50-60 deg.C until the conductivity of the filtrate is less than 1 μ s/cm;

drying the washed filter cake at 110 ℃ overnight, and then roasting at 700 ℃ for 5 h;

and crushing and screening the roasted oxide product to obtain holmium oxide powder.

Example 2

The preparation was carried out as described in example 1, except that holmium oxide (Ho) was used₂O₃) Changeable pipeHolmium sulfate (Ho) with a calculated concentration of 50g/L₂(SO₄)₃) The solution is used as a starting material for carrying out precipitation reaction.

Example 3

The preparation was carried out as described in example 1, except that holmium oxide (Ho) was used₂O₃) Holmium nitrate (Ho (NO) in a converted concentration of 50g/L₃)₃) The solution is used as a starting material for carrying out precipitation reaction.

Example 4

The preparation was carried out as described in example 1, except that holmium oxide (Ho) was used₂O₃) Holmium chloride (HoCl) in a converted concentration of 100g/L₃) The solution is used as a starting material for carrying out precipitation reaction.

Example 5

The preparation was carried out as described in example 1, except that the precipitation reaction and aging treatment were carried out at 70 ℃.

Example 6

The preparation was carried out as described in example 1, except that ammonium carbonate ((NH) was used in a concentration of 1.0mol/L₄)₂CO₃) The solution is used as a precipitant to carry out precipitation reaction.

Example 7

The procedure was as described in example 1, except that ammonium hydrogencarbonate (NH) was used in a concentration of 1.0mol/L₄HCO₃) The solution is used as a precipitant to carry out precipitation reaction.

Example 8

The procedure was carried out as described in example 1, except that a mixed solution of an ammonium carbonate solution having a concentration of 1.0mol/L and a sodium hydroxide (NaOH) solution having a concentration of 0.5mol/L was used as a precipitant to carry out the precipitation reaction.

Example 9

The preparation was carried out as described in example 1, except that an ammonium carbonate solution having a concentration of 1.0mol/L and an aqueous ammonia solution (NH) having a concentration of 0.5mol/L were used₄OH) as a precipitant to perform precipitation reaction.

Example 10

The procedure was carried out as described in example 1, except that the precipitation reaction was carried out using a mixed solution of an ammonium hydrogencarbonate solution at a concentration of 1.0mol/L and an aqueous ammonia solution at a concentration of 0.5mol/L as a precipitant.

The finished products of examples 1-10 were tested for performance and the results are shown in Table 1.

TABLE 1

As can be seen from Table 1, the finished products of examples 1-10 have small particle sizes and good dispersibility.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. A preparation method of nano holmium oxide for a dielectric ceramic capacitor is characterized by comprising the following specific steps:

preparing a holmium salt solution and an alkaline precipitator solution, wherein the concentration of holmium oxide in the holmium salt solution is 30-400g-REO/L, the concentration of free acid in the holmium salt solution is 0.05-2.0mol/L, and the concentration of hydroxyl in the alkaline precipitator solution is 0.1-10 mol/L;

step two, stirring and heating a holmium salt solution to 30-100 ℃, slowly dropping an alkaline precipitator solution into the holmium salt solution, and controlling the final pH value of the solution after precipitation to be 4.5-9.0;

thirdly, aging the precipitate precursor at 45-150 ℃ for 0.25-15 h;

filtering and washing the aged precipitate precursor, wherein the conductivity of the filtered filtrate is less than 1 mu s/cm, and the washing temperature is 40-80 ℃;

and step five, drying, roasting, crushing and screening the washed precipitate precursor to obtain a finished product.

2. The method of claim 1, wherein the holmium salt solution in the first step includes at least one of a holmium chloride solution, a holmium sulfate solution and a holmium nitrate solution.

3. The method of preparing nano holmium oxide for dielectric ceramic capacitors as claimed in claim 1 or 2, wherein the alkaline precipitant solution in the first step includes one or more of sodium hydroxide solution, potassium hydroxide solution, ammonia water solution, sodium carbonate solution, sodium bicarbonate solution, ammonium carbonate solution and ammonium bicarbonate solution.

4. The method of claim 1, wherein the dropping of the alkali precipitant solution into the holmium salt solution in the second step is performed for 0.25-8 h.

5. The method for preparing nano holmium oxide for dielectric ceramic capacitors as claimed in claim 1 or 4, wherein the calcination temperature in the fifth step is 500-950 ℃ and the calcination time is 2-20 h.

6. The method of preparing nano holmium oxide for dielectric ceramic capacitors as claimed in claim 1, wherein the holmium oxide concentration in the holmium salt solution is 40-300 g-REO/L.

7. The method of claim 1, wherein the concentration of hydroxyl group in the alkaline precipitant solution is 0.3 to 5 mol/L.