Preparation method of manganese dioxide doped barium titanate-based dielectric material

Abstract

The invention discloses a preparation method of a manganese dioxide doped barium titanate-based dielectric material, which comprises the following steps: (1) adding MnO2 according to the molar weight of 0.3-1.0 mol%, and mixing with BaTiO3 to obtain a mixture; (2) putting the mixture into a ball-milling tank, adding zirconium oxide pellets and absolute ethyl alcohol, performing ball-milling for 24-26 hours at the rotating speed of 450-480 r / min, drying the ball-milled powder, and then performing sieving treatment through a 150-mesh screen to obtain sieved dried powder; (3) adding 8wt% of a binder into the sieved dried powder, sieving with a 150-mesh sieve, granulating, tabletting and forming to obtain a green body; and (4) discharging the binder from the green body, sintering the green body in a reducing atmosphere at 1200-1300 DEG C, and keeping the temperature for 1-2 hours to obtain the product. The dielectric constant and the insulation resistivity of the prepared manganese dioxide doped barium titanate-based dielectric material are higher than those of a sintered sample in air.

Description

Technical Field

[0001] The invention belongs to the technical field of dielectric materials and relates to a method for preparing a manganese dioxide-doped barium titanate-based dielectric material. Background Art

[0002] Currently, driven by the 5G era, smart phones, new energy vehicles and other fields, the electronic information industry is booming. Among them, multilayer ceramic capacitors (MLCC), as the electronic components with the highest market share, have become one of the products of basic component technology innovation.

[0003] At present, the internal electrodes in MLCC are mainly precious metals such as silver-palladium alloys. In recent years, the price of precious metals has increased rapidly, so it is necessary to develop base metal internal electrodes (BME) such as nickel and copper to further reduce production costs. MLCC needs to be sintered in a reducing atmosphere to prevent oxidation of base metals, but in a reducing atmosphere, Ti 4+ Will be restored to Ti 3+ This leads to a decrease in reliability, so it is of great significance to resist reducing agents to dope barium titanate-based ceramics. Summary of the invention

[0004] The purpose of the present invention is to achieve low-cost production of MLCC, use base metal as internal electrode sintering in a reducing atmosphere, and inhibit the oxidation of BaTiO3 dielectric material, thereby providing a preparation method of manganese dioxide doped barium titanate-based dielectric material.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides a method for preparing a manganese dioxide-doped barium titanate-based dielectric material, comprising the following steps:

[0007] (1) adding MnO2 in a molar amount of 0.3 to 1.0 mol% and mixing with BaTiO3 to obtain a mixed material;

[0008] (2) placing the mixture obtained in step (1) into a ball mill, adding zirconium oxide balls and anhydrous ethanol, and ball milling at a rotation speed of 450 to 480 r / min for 24 to 26 hours, drying the ball-milled powder, and then sieving it through a 150-mesh sieve to obtain a sieved and dried powder;

[0009] (3) adding 8 wt% of a binder to the sieved and dried powder obtained in step (2), sieving through a 150-mesh screen, granulating, and tableting to obtain a green embryo;

[0010] (4) The green body obtained in step (3) is first freed from the binder, and then sintered in a reducing atmosphere at 1200-1300° C. and kept warm for 1-2 hours to obtain a manganese dioxide-doped barium titanate-based dielectric material.

[0011] Furthermore, the purity of the raw materials in step (1) is above 99%.

[0012] Furthermore, in step (2), the mass ratio of the zirconium oxide balls, the mixture and the anhydrous ethanol is (1.5-1.6):1:1.

[0013] Preferably, the diameter of the zirconium oxide spheres is 3 mm.

[0014] Furthermore, the powder after ball milling in step (2) is dried in an oven at 80-100°C.

[0015] Furthermore, the binder in step (3) is PVA.

[0016] Furthermore, the tableting process in step (3) has a molding pressure of 350 to 400 MPa.

[0017] Furthermore, the green body in step (3) is a small disc of φ8mm×1mm.

[0018] Furthermore, in step (4), the binder removal process is to first heat the temperature to 300-350°C, keep the temperature for 0.5h, then heat the temperature to 600-650°C, keep the temperature for 0.5h, and the heating rate is 1-2°C / min.

[0019] Furthermore, in step (4), the heating rate of sintering in a reducing atmosphere at 1200-1300° C. is 3-5° C. / min, and the cooling rate is 8-10° C. / min.

[0020] Furthermore, in step (4), a GSL-1700X dual-temperature zone high-temperature tube furnace is used for sintering.

[0021] Another aspect of the present invention provides a manganese dioxide-doped barium titanate-based dielectric material prepared by the preparation method.

[0022] The beneficial effects of the present invention are:

[0023] The invention provides a method for preparing a manganese dioxide-doped barium titanate-based dielectric material, wherein the sintering atmosphere is a reducing atmosphere, the sintering temperature is 1200-1300° C. The dielectric constant and insulation resistivity of the prepared manganese dioxide-doped barium titanate-based dielectric material are higher than those of the sample sintered in air, and the material can be used for the preparation of multilayer ceramic capacitors (MLCCs). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is the graph showing the change of dielectric constant of the sample sintered in reducing atmosphere with temperature;

[0025] Figure 2 This is the graph showing the change of dielectric loss with temperature of the sample sintered in reducing atmosphere;

[0026] Figure 3 This is the graph showing the change of dielectric constant of air-sintered samples with temperature;

[0027] Figure 4 The graph of dielectric loss of air-sintered samples changing with temperature;

[0028] Figure 5 EPR spectra were measured for samples sintered in air and reducing atmosphere. DETAILED DESCRIPTION

[0029] In order to understand the present invention more clearly, the present invention is further described with reference to the following examples and accompanying drawings. The examples are only used for explanation and are not intended to limit the present invention in any way. In the examples, each raw material reagent is commercially available, and the experimental methods without specifying specific conditions are conventional methods and conventional conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0030] The embodiments and comparative examples used a GSL-1700X dual-temperature zone high-temperature tube furnace for sintering, and a KSL-1700X box furnace for silver infiltration.

[0031] The diameter of the zirconium oxide balls in the examples and comparative examples is 3 mm.

[0032] In the embodiments and comparative examples, the binder removal process is to first heat up to 300-350° C., keep warm for 0.5 h, then heat up to 600-650° C., keep warm for 0.5 h, and the heating rate is 1-2° C. / min.

[0033] In the embodiments and comparative examples, the heating rate of sintering is 3-5°C / min, and the cooling rate is 8-10°C / min.

[0034] Example 1

[0035] (1) Weigh 23.319 g of BaTiO3 and add 0.3% by mole of MnO2 to the mixture;

[0036] (2) The powder prepared in step (1) is placed in a ball mill, zirconium oxide balls and anhydrous ethanol are added, and the mixture is ball milled at a speed of 450 r / min for 24 h. The mass ratio of zirconium oxide balls, powder and anhydrous ethanol is 1.5:1:1. The ball-milled powder is placed in an oven at 100° C. and dried, and then sieved with a 150-mesh sieve to obtain a uniform powder.

[0037] (3) Take 10 g of the uniform powder obtained in step (2), add 0.9 g of 8 wt % PVA binder, and then sieve through a 150-mesh sieve to form granules.

[0038] (4) The powder granulated in step (3) is pressed into a green body of φ8 mm×1 mm at a pressure of 357 MPa using a tablet press. The green body is firstly freed from a binder and then sintered at 1250°C in a reducing atmosphere for 1 hour to obtain a MnO2-doped BaTiO3-based dielectric material.

[0039] (5) The dielectric material obtained in step (4) is silver-plated on a heating table and then placed in a muffle furnace for silver infiltration.

[0040] Example 2

[0041] (1) Weigh 23.319 g of BaTiO3 and add 0.6% by mole of MnO2 to the mixture;

[0042] (2) The powder prepared in step (1) is placed in a ball mill, zirconium oxide balls and anhydrous ethanol are added, and the mixture is ball milled at a speed of 450 r / min for 24 h. The mass ratio of zirconium oxide balls, powder and anhydrous ethanol is 1.5:1:1. The ball-milled powder is placed in an oven at 100° C. and dried, and then sieved with a 150-mesh sieve to obtain a uniform powder.

[0043] (3) Take 10 g of the uniform powder obtained in step (2), add 0.9 g of 8 wt % PVA binder, and then sieve through a 150-mesh sieve to form granules.

[0044] (4) The powder granulated in step (3) is pressed into a green body of φ8 mm×1 mm at a pressure of 357 MPa using a tablet press. The green body is firstly freed from a binder and then sintered at 1250°C in a reducing atmosphere for 1 hour to obtain a MnO2-doped BaTiO3-based dielectric material.

[0045] (5) The dielectric material obtained in step (4) is silver-plated on a heating table and then placed in a muffle furnace for silver infiltration.

[0046] Example 3

[0047] (1) Weigh 23.319 g of BaTiO3 and add 1.0% by mole of MnO2 to the mixture;

[0048] (2) The powder prepared in step (1) is placed in a ball mill, zirconium oxide balls and anhydrous ethanol are added, and the mixture is ball milled at a speed of 450 r / min for 24 h. The mass ratio of zirconium oxide balls, powder and anhydrous ethanol is 1.5:1:1. The ball-milled powder is placed in an oven at 100° C. and dried, and then sieved with a 150-mesh sieve to obtain a uniform powder.

[0049] (3) Take 10 g of the uniform powder obtained in step (2), add 0.9 g of 8 wt % PVA binder, and then sieve through a 150-mesh sieve to form granules.

[0050] (4) The powder granulated in step (3) is pressed into a green body of φ8 mm×1 mm at a pressure of 357 MPa using a tablet press. The green body is firstly freed from a binder and then sintered at 1250°C in a reducing atmosphere for 1 hour to obtain a MnO2-doped BaTiO3-based dielectric material.

[0051] (5) The dielectric material obtained in step (4) is silver-plated on a heating table and then placed in a muffle furnace for silver infiltration.

[0052] Comparative Example 1

[0053] (1) Weigh 23.319 g of BaTiO3 and add 0.3% by mole of MnO2 to the mixture;

[0054] (2) The powder prepared in step (1) is placed in a ball mill, zirconium oxide balls and anhydrous ethanol are added, and the mixture is ball milled at a speed of 450 r / min for 24 h. The mass ratio of zirconium oxide balls, powder and anhydrous ethanol is 1.5:1:1. The ball-milled powder is placed in an oven at 100° C. and dried, and then sieved with a 150-mesh sieve to obtain a uniform powder.

[0055] (3) Take 10 g of the uniform powder obtained in step (2), add 0.9 g of 8 wt % PVA binder, and then sieve through a 150-mesh sieve to form granules.

[0056] (4) The powder granulated in step (3) is compressed by a tablet press at a pressure of 357 MPa. The green body is prepared, the binder is first removed from the green body, and then sintered at 1250°C in air and kept warm for 1 hour to obtain the MnO2-doped BaTiO3-based dielectric material.

[0057] (5) The dielectric material obtained in step (4) is silver-plated on a heating table and then placed in a muffle furnace for silver infiltration.

[0058] Comparative Example 2

[0059] (1) Weigh 23.319 g of BaTiO3 and add 0.6% by mole of MnO2 to the mixture;

[0060] (2) The powder prepared in step (1) is placed in a ball mill, zirconium oxide balls and anhydrous ethanol are added, and the mixture is ball milled at a speed of 450 r / min for 24 h. The mass ratio of zirconium oxide balls, powder and anhydrous ethanol is 1.5:1:1. The ball-milled powder is placed in an oven at 100° C. and dried, and then sieved with a 150-mesh sieve to obtain a uniform powder.

[0061] (3) Take 10 g of the uniform powder obtained in step (2), add 0.9 g of 8 wt % PVA binder, and then sieve through a 150-mesh sieve to form granules.

[0062] (4) The powder granulated in step (3) is compressed by a tablet press at a pressure of 357 MPa. The green body is prepared, the binder is first removed from the green body, and then sintered at 1250°C in air and kept warm for 1 hour to obtain the MnO2-doped BaTiO3-based dielectric material.

[0063] (5) The dielectric material obtained in step (4) is silver-plated on a heating table and then placed in a muffle furnace for silver infiltration.

[0064] Comparative Example 3

[0065] (1) Weigh 23.319 g of BaTiO3 and add 1.0% by mole of MnO2 to the mixture;

[0066] (2) The powder prepared in step (1) is placed in a ball mill, zirconium oxide balls and anhydrous ethanol are added, and the mixture is ball milled at a speed of 450 r / min for 24 h. The mass ratio of zirconium oxide balls, powder and anhydrous ethanol is 1.5:1:1. The ball-milled powder is placed in an oven at 100° C. and dried, and then sieved with a 150-mesh sieve to obtain a uniform powder.

[0067] (3) Take 10 g of the uniform powder obtained in step (2), add 0.9 g of 8 wt % PVA binder, and then sieve through a 150-mesh sieve to form granules.

[0068] (4) The powder granulated in step (3) is compressed by a tablet press at a pressure of 357 MPa. The green body is prepared, the binder is first removed from the green body, and then sintered at 1250°C in air and kept warm for 1 hour to obtain the MnO2-doped BaTiO3-based dielectric material.

[0069] (5) The dielectric material obtained in step (4) is silver-plated on a heating table and then placed in a muffle furnace for silver infiltration.

[0070] The performance test is carried out by the following method:

[0071] Dielectric properties: Novocontrol broadband dielectric impedance spectrometer was used to test the sample capacitance and dielectric loss, and then the dielectric constant was calculated; the test temperature range was -60℃~200℃, the heating rate was 2℃ / min, the test frequency was 1kHz, the AC voltage was 1V, and data was collected every 2℃. The conversion formula for the wafer dielectric constant is as follows:

[0072]

[0073] Where ε and ε0 are the dielectric constant and vacuum dielectric constant, respectively, in F / m; C is the capacitance, in F; d and D are the thickness and diameter, respectively, in mm.

[0074] Insulation resistivity: Use B2985A resistance meter to test the sample resistance; the test voltage is DC 600V, the test time is 1h, record the stable resistance value on the instrument panel, and then calculate the insulation resistivity based on the area and thickness of the wafer. The formula for the insulation resistivity of the wafer is as follows:

[0075]

[0076] Where ρ is the insulation resistivity, in Ω / mm; R is the resistance value, in Ω; d and F are the thickness and diameter, in mm respectively.

[0077] The properties of the MnO2-doped BaTiO3-based dielectric materials prepared in Examples 1-3 and Comparative Examples 1-3 are shown in Tables 1 and Figure 1-5 shown.

[0078] The experimental results show that the dielectric constant and insulation resistivity of the samples sintered in reducing atmosphere are higher than those of the samples sintered in air. From the EPR spectrum, it can be seen that the samples sintered in reducing atmosphere have obvious Mn 2+ The six-line fine structure of the sample in air is almost absent. 4+ Transformed into Mn 2+ It plays an anti-reduction role and is beneficial to the dielectric constant and insulation resistance rates.

[0079] Table 1

[0080]

[0081] The above embodiments are only for illustrating the main concepts and principles of the present invention. Any equivalent substitutions and improvements made according to the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a manganese dioxide-doped barium titanate-based dielectric material, characterized in that: The steps include: (1) adding MnO2 in a molar amount of 0.3 to 1.0 mol% and mixing with BaTiO3 to obtain a mixed material; (2) placing the mixture obtained in step (1) into a ball mill, adding zirconium oxide balls and anhydrous ethanol, and ball milling at a rotation speed of 450 to 480 r / min for 24 to 26 hours, drying the ball-milled powder, and then sieving it through a 150-mesh sieve to obtain a sieved and dried powder; (3) adding 8 wt% of a binder to the sieved and dried powder obtained in step (2), sieving through a 150-mesh screen, granulating, and tableting to obtain a green embryo; (4) The green body obtained in step (3) is first freed from the binder, and then sintered in a reducing atmosphere at 1200-1300° C. and kept warm for 1-2 hours to obtain a manganese dioxide-doped barium titanate-based dielectric material.

2. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of the zirconium oxide balls, the mixture and the anhydrous ethanol is (1.5-1.6):1:

1. Preferably, the diameter of the zirconia sphere is 3 mm.

3. The preparation method according to claim 1, characterized in that: The powder after ball milling in step (2) is dried in an oven at 80-100°C.

4. The preparation method according to claim 1, characterized in that: The binder in step (3) is PVA.

5. The preparation method according to claim 1, characterized in that: The tableting process in step (3) has a molding pressure of 350 to 400 MPa.

6. The preparation method according to claim 1, characterized in that: The green body in step (3) is a small disc of φ8mm×1mm.

7. The preparation method according to claim 1, characterized in that: In step (4), the binder removal process is to first heat the temperature to 300-350°C, keep the temperature for 0.5h, then heat the temperature to 600-650°C, keep the temperature for 0.5h, and the heating rate is 1-2°C / min.

8. The preparation method according to claim 1, characterized in that: In step (4), the heating rate of sintering in a reducing atmosphere at 1200-1300° C. is 3-5° C. / min, and the cooling rate is 8-10° C. / min.

9. The preparation method according to claim 1, characterized in that: In step (4), a GSL-1700X dual-temperature zone high-temperature tube furnace is used for sintering.

10. Manganese dioxide-doped barium titanate-based dielectric material prepared by the preparation method according to any one of claims 1 to 9.

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