Barium titanate ceramic capacitor material and preparation method thereof

Abstract

The invention discloses a barium titanate ceramic capacitor material and a preparation method thereof, the composition of the barium titanate ceramic capacitor material is represented as (1-a-b-c-d-e) BaTiO3-aNb2O5-bGd2O3-cB2O3-dSiO2-eMn3O4, a = 0.008-0.012, b = 0.002-0.005, c = 0.001-0.004, d = 0.001-0.004, and e = 0.002-0.004, the preparation method comprises the following steps: (1) mixing Nb2O5, Gd2O3, B2O3, SiO2 and Mn3O4 according to a ratio, carrying out mixing, ball milling and sieving, and then carrying out first sintering treatment; (2) adding BaTiO3 into the material prepared in the step (1), mixing and ball-milling, and drying; and (3) carrying out compression molding on the material obtained in the step (2), and then carrying out secondary sintering treatment. The barium titanate ceramic capacitor material disclosed by the invention realizes low loss and high temperature stability while keeping relatively high dielectric.

Description

Technical Field

[0001] This invention specifically relates to a barium titanate ceramic capacitor material and its preparation method. Background Technology

[0002] Barium titanate has excellent ferroelectric properties and is widely used in the manufacture of electronic components such as multilayer ceramic capacitors (MLCCs), piezoelectric ceramics, positive temperature coefficient thermistors (PTCRs), and information storage devices.

[0003] Equipment used in field and outdoor X-ray source generating instruments and other equipment needs to generate high-voltage power under extreme conditions. The high-voltage power generator requires capacitors with high dielectric constant, low loss, and temperature stability. However, in the current technology, excluding lead-containing materials, there is no suitable composition that can simultaneously maintain high values ​​for the three parameters of dielectric constant, loss, and temperature stability of barium titanate ceramic capacitors. In other words, the existing system is unable to achieve a balance between high dielectric constant, low loss, and high temperature stability. For example, Japanese patent JP1990311362A achieves a dielectric constant of 4600-5500 and a loss of 0.5-0.9%, but its TCC only reaches Y5T. Similarly, Japanese patent JP1988039540B2 achieves a dielectric constant of 2900-4000 and a loss of 0.8-1.3%, but as seen in the specification, its optimal temperature stability (-25-85℃) only reaches Y5P, far below the X7R level. Furthermore, Japanese patent JP1983032068A achieves a dielectric constant of 6300-7700 and a loss of 0.35-0.85%, but as seen in the specification, its optimal temperature stability (-25-85℃) only reaches Y5U, far below the X7R level.

[0004] The present invention is made to address the aforementioned problems existing in the prior art. Summary of the Invention

[0005] To address the challenge of simultaneously achieving high dielectric constant, low loss, and high temperature stability in existing technologies, this invention provides a barium titanate ceramic capacitor material and its preparation method. This barium titanate ceramic capacitor material achieves both low loss and high temperature stability while maintaining high dielectric constant.

[0006] The technical solution of this invention is as follows: This invention provides a barium titanate ceramic capacitor material, the composition of which is as follows: (1-abcde)BaTiO3-aNb2O5-bGd2O3-cB2O3-dSiO2-eMn3O4, where a=0.008-0.012, b=0.002-0.005, c=0.001-0.004, d=0.001-0.004, e=0.002-0.004.

[0007] Preferably, a=0.01, b=0.003, c=0.002, d=0.002, e=0.002-0.004.

[0008] This invention also provides a method for preparing barium titanate ceramic capacitor material, comprising the following steps: (1) Nb2O5, Gd2O3, B2O3, SiO2 and Mn3O4 are mixed in a molar ratio of a:b:c:d:e, and the mixture is ball-milled, sieved and then subjected to a first sintering treatment; wherein a=0.008-0.012, b=0.002-0.005, c=0.001-0.004, d=0.001-0.004 and e=0.002-0.004; (2) Add BaTiO3 to the material obtained in step (1), mix and ball mill, and then dry; wherein the molar ratio of BaTiO3 to Nb2O5 used in step (1) is (1-abcde):a; (3) Press the material obtained in step (2) into shape, and then perform a second sintering treatment.

[0009] Preferably, in step (1), the conditions for the first sintering treatment are: heating to 850°C at 2°C / min and holding for 2 hours.

[0010] Preferably, in step (1), the mixture is ball-milled until D50 < 500 nm and D90 < 1000 nm, and in step (2), the mixture is ball-milled until D50 < 500 nm and D90 < 1000 nm.

[0011] Preferably, in step (1), the mixture is ball-milled until D50 < 300 nm and D90 < 500 nm, and in step (2), the mixture is ball-milled until D50 < 400 nm and D90 < 900 nm.

[0012] Preferably, in step (1), the mixture is ball-milled until D50 < 250 nm and D90 < 400 nm, and in step (2), the mixture is ball-milled until 350 nm. <D50<400nm,750nm<D90<900nm。

[0013] Preferably, in step (3), the material is pressed at 300-500 MPa.

[0014] Preferably, in step (3), the conditions for the second sintering treatment are: first, heat the temperature to 280℃ at 2℃ / min and hold for 2h, then heat the temperature to 1250℃ at 3℃ / min and hold for 2h.

[0015] The beneficial effects of this invention are: For barium iron titanate ceramic capacitors, since their Curie peak is around 125℃, the dielectric constant of the material increases significantly at high temperatures. Nb₂O₅ has the effect of suppressing the dielectric constant at high temperatures, and adding a certain amount of Nb₂O₅ helps to stabilize the temperature coefficient of the material at high temperatures. Mn₃O₄ can reduce the dielectric loss of the material, and the incorporation of Mn can promote the formation of defect dipoles, effectively reducing carrier migration and improving the reliability of the ceramic, especially Mn. 3+ Ion doping can also effectively reduce Ti 4+ The reduction of ferroelectricity inhibits the degradation of ferroelectricity, reduces leakage current, and thus improves the stability of the capacitor. The addition of Gd2O3 stabilizes the temperature coefficient of the material in the low-temperature range, and the B and Si elements reduce the sintering temperature. By controlling the amount of each raw material added, the barium titanate ceramic capacitor material prepared by this invention achieves low loss and high temperature stability while maintaining a high dielectric constant. With a dielectric constant as high as 3000 and a loss of <0.5%, the TCC can reach X7R. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the invention.

[0017] A method for preparing barium titanate ceramic capacitor material includes the following steps: (1) Nb2O5, Gd2O3, B2O3, SiO2 and Mn3O4 are mixed in a molar ratio of a:b:c:d:e. The mixture is ball-milled until D50<300nm and D90<500nm. Then it is sieved and subjected to the first sintering treatment. The temperature is increased to 850℃ at 2℃ / min and held for 2h.

[0018] (2) Add BaTiO3 to the material obtained in step (1), mix and ball mill until D50 < 400 nm, D90 < 900 nm, and then dry; wherein, the molar ratio of BaTiO3 to Nb2O5 used in step (1) is (1-abcde):a.

[0019] (3) Press the material obtained in step (2) at 500 MPa and then perform a second sintering treatment. First, heat the material to 280℃ at 2℃ / min and hold for 2 hours, then heat it to 1250℃ at 3℃ / min and hold for 2 hours. Then, cool it naturally to room temperature to obtain barium titanate ceramic capacitor material.

[0020] The barium titanate ceramic capacitor materials of Examples 1-9 were prepared according to the proportions in Table 1 below, and their performance was tested. The results are shown in Table 1.

[0021] Dielectric loss: Ceramic capacitors prepared according to the methods in Examples 1-9 were randomly selected and their dielectric loss was tested. Using a Tonghui TH2838 precision LCR digital bridge instrument, the capacitance and loss of the prepared ceramic capacitor disc with a diameter of 14 mm and a thickness of 4 mm were tested at 1 kHz and room temperature. The average value of multiple test results was taken as the result, and the corresponding dielectric constant was calculated.

[0022] Temperature stability test: ceramic capacitor discs with a diameter of 14 mm and a thickness of 4 mm prepared according to the methods of Examples 1-9 were randomly selected. The capacitance and loss values ​​at different temperatures were tested using a Tonghui TH2838 precision LCR digital bridge instrument connected to a Julang temperature testing instrument. The average value of multiple test results was taken as the result.

[0023] Table 1

[0024] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A barium titanate ceramic capacitor material, characterized in that, Its composition is represented as follows: (1-abcde)BaTiO3-aNb2O5-bGd2O3-cB2O3-dSiO2-eMn3O4, where a=0.008-0.012, b=0.002-0.005, c=0.001-0.004, d=0.001-0.004, e=0.002-0.

004.

2. The barium titanate ceramic capacitor material according to claim 1, characterized in that, a=0.01, b=0.003, c=0.002, d=0.002, e=0.002-0.

004.

3. A method for preparing barium titanate ceramic capacitor material, characterized in that, Includes the following steps: (1) Nb2O5, Gd2O3, B2O3, SiO2 and Mn3O4 are mixed in a molar ratio of a:b:c:d:e, and the mixture is ball-milled, sieved and then subjected to a first sintering treatment; wherein a=0.008-0.012, b=0.002-0.005, c=0.001-0.004, d=0.001-0.004 and e=0.002-0.004; (2) Add BaTiO3 to the material obtained in step (1), mix and ball mill, and then dry; wherein the molar ratio of BaTiO3 to Nb2O5 used in step (1) is (1-abcde):a; (3) Press the material obtained in step (2) into shape, and then perform a second sintering treatment.

4. The method for preparing barium titanate ceramic capacitor material according to claim 3, characterized in that, In step (1), the conditions for the first sintering treatment are: heating to 850℃ at 2℃ / min and holding for 2h.

5. The method for preparing barium titanate ceramic capacitor material according to claim 3, characterized in that, In step (1), the mixture is ball-milled until D50 < 500 nm and D90 < 1000 nm. In step (2), the mixture is ball-milled until D50 < 500 nm and D90 < 1000 nm.

6. The method for preparing barium titanate ceramic capacitor material according to claim 5, characterized in that, In step (1), the mixture is ball-milled until D50 < 300 nm and D90 < 500 nm. In step (2), the mixture is ball-milled until D50 < 400 nm and D90 < 900 nm.

7. The method for preparing barium titanate ceramic capacitor material according to claim 6, characterized in that, In step (1), the mixture is ball-milled until D50 < 250 nm and D90 < 400 nm. In step (2), the mixture is ball-milled until 350 nm. <D50<400nm,750nm<D90<900nm。 8. The method for preparing barium titanate ceramic capacitor material according to claim 3, characterized in that, In step (3), the material is pressed at 300-500 MPa.

9. The method for preparing barium titanate ceramic capacitor material according to claim 3, characterized in that, In step (3), the conditions for the second sintering treatment are: first, heat the temperature to 280℃ at 2℃ / min and hold for 2h, then heat the temperature to 1250℃ at 3℃ / min and hold for 2h.

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