Double-metal-element-doped CCTO modified dielectric ceramic material and preparation method thereof

Abstract

The invention discloses a double-metal-element-doped CCTO modified dielectric ceramic material and a preparation method thereof, and belongs to the technical field of dielectric functional ceramic materials, and the chemical formula of the double-metal-element-doped CCTO modified dielectric ceramic material is CaCu < 3-x > Zn < x > Ti < 3.95 > Zr < 0.05 > O < 12 >, wherein 0 lt; xlt; 3. According to the double-metal-element-doped CCTO modified dielectric ceramic material and the preparation method thereof, dielectric loss is effectively reduced, a high dielectric constant is kept, CCTO frequency dependence is improved, and efficient and stable dielectric performance in a broadband area is kept.

Description

Technical Field

[0001] The present invention relates to the technical field of dielectric functional ceramic materials, and in particular to a bimetal element-doped CCTO modified dielectric ceramic material and a preparation method thereof. Background Art

[0002] The high dielectric constant of CCTO stems from its unique perovskite structure, which enables the material to generate a polarization effect under the action of an external electric field. However, CCTO has disadvantages such as high dielectric loss, strong process sensitivity, and poor frequency stability of dielectric properties, which seriously restrict the practical application of CCTO ceramics. Research shows that the dielectric properties of CCTO materials are closely related to their microstructure, and doping trace metal elements can effectively adjust their crystal structure and electrical properties. Patent CN115321976B discloses a giant dielectric constant, low dielectric loss CCTO ceramic material and a preparation method thereof. Co-doping with Nd and Nb reduces the low-frequency dielectric loss of the material while maintaining a high dielectric constant, overcoming the deficiency of the traditional method of doping high-insulating ceramics that leads to a decrease in dielectric constant. However, its optimal sintering temperature is 1100 °C, and the lowest dielectric loss is only 0.02. The dielectric loss varies greatly with frequency in a wide frequency range and cannot maintain the stability of dielectric properties. In addition, the high sintering temperature will lead to an increase in energy consumption. Summary of the Invention

[0003] The purpose of the present invention is to provide a bimetal element-doped CCTO modified dielectric ceramic material and a preparation method thereof, which can effectively reduce dielectric loss, maintain a high dielectric constant, improve the frequency dependence of CCTO, and maintain efficient and stable dielectric properties in a wide frequency range.

[0004] To achieve the above purpose, the present invention provides a bimetal element-doped CCTO modified dielectric ceramic material. The chemical formula of the bimetal element-doped CCTO modified dielectric ceramic material is CaCu 3-x Zn x Ti 3.95 Zr 0.05 O 12 ; wherein, 0 < x < 3.

[0005] The present invention provides a preparation method of a bimetal element-doped CCTO modified dielectric ceramic material, including the following steps:

[0006] S1. Mix calcium nitrate tetrahydrate, copper nitrate trihydrate, tetrabutyl titanate, zinc nitrate hexahydrate, and zirconium oxynitrate with a solvent respectively, cover with plastic wrap and stir to obtain solution A, solution B, solution C, solution D, and solution E;

[0007] S2. Mix solution A, solution B, solution C, solution D, and solution E to obtain a precursor solution;

[0008] S3. Adjust the pH of the precursor solution with concentrated nitric acid, and obtain the CCTO colloid after stirring and aging;

[0009] S4. Dry the CCTO colloid in a vacuum oven to obtain a dry gel, and put the dry gel into a ball mill to grind it into powder;

[0010] S5. Put the milled powder into a muffle furnace for sintering, and obtain powder F after cooling to room temperature;

[0011] S6. Mix the powder F and the PVA binder evenly, and use a tablet press to press tablets to obtain smooth-surfaced round tablets;

[0012] S7. Anneal the round tablets in a muffle furnace, and obtain CaCu 3-x Zn x Ti 3.95 Zr 0.05 O 12 ceramic material.

[0013] Preferably, in S1, the solvent is one of deionized water and absolute ethanol;

[0014] The solvents of solution A and solution D are both deionized water;

[0015] The solvents of solution B, solution C and solution D are all absolute ethanol.

[0016] Preferably, in S1, the stirring time is 10 - 30 min.

[0017] Preferably, in S2, the molar ratio of Ca, Cu, Zn, Ti, Zr in the precursor solution is 1:(2.9 - 2.975):(0.025 - 0.1):3.95:0.05.

[0018] Preferably, in S3, the concentration of concentrated nitric acid is 60 - 70%, the pH value of the precursor solution is adjusted to 1 - 2, the stirring time is 1 - 3 h, and the aging time is 36 - 72 h.

[0019] Preferably, in S4, the drying temperature is 80 - 100 °C and the drying time is 48 - 96 h.

[0020] Preferably, in S5, the specific sintering operation is: heat from room temperature to 350 - 400 °C at a heating rate of 5 - 10 °C / min, hold for 3 - 4 h, then heat to 900 - 950 °C and hold for 10 - 12 h.

[0021] Preferably, in S6, the concentration of the PVA binder is 3 - 7%.

[0022] Preferably, in S7, the specific operation of the annealing treatment is as follows: first, heat up to 300 - 350 °C, keep warm for 1 - 2 h, then heat up to 700 - 750 °C, keep warm for 1 - 2 h, and finally heat up to 900 - 1000 °C, keep warm for 4 - 6 h.

[0023] Therefore, by adopting the above-mentioned bimetallic element-doped CCTO modified dielectric ceramic material and its preparation method, the present invention has the following beneficial effects:

[0024] (1) Using the sol-gel method to prepare the CCTO ceramic material doped with Zn and Zr is not restricted by the solid-phase reaction mechanism, enabling an accurate amount of doped ions to enter the lattice of CCTO and replace the corresponding ion positions at a relatively low sintering temperature, thereby preparing a CaCu 3-x Zn x Ti 3.95 Zr 0.05 O 12 ceramic material with uniform mixing, high density, and strong mechanical properties;

[0025] (2) Using the sol-gel method to prepare the CCTO ceramic material doped with Zn and Zr, by controlling the doping ratio of Zn 2+ and the annealing temperature to regulate the microstructure of CCTO, effectively improving the dielectric constant of the material and improving the dependence of dielectric properties on frequency.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0027] Figure 1 is the XRD pattern of the ceramic materials of Examples 1 - 4 of the bimetallic element-doped CCTO modified dielectric ceramic material and its preparation method of the present invention;

[0028] Figure 2 is the curve graph of the dielectric constant varying with frequency of the ceramic materials with an annealing temperature of 900 °C prepared in Examples 1 - 4 of the bimetallic element-doped CCTO modified dielectric ceramic material and its preparation method of the present invention;

[0029] Figure 3 is the curve graph of the dielectric constant varying with frequency of the ceramic materials with an annealing temperature of 1000 °C prepared in Examples 5 - 8 of the bimetallic element-doped CCTO modified dielectric ceramic material and its preparation method of the present invention;

[0030] Figure 4 is the curve graph of the dielectric loss varying with frequency of the ceramic materials with an annealing temperature of 900 °C prepared in Examples 1 - 4 of the bimetallic element-doped CCTO modified dielectric ceramic material and its preparation method of the present invention;

[0031] Figure 5 It is a graph showing the variation of dielectric loss with frequency of the ceramic material with an annealing temperature of 1000 °C prepared in Examples 1-4 of a bimetal element-doped CCTO modified dielectric ceramic material and its preparation method of the present invention. Specific embodiments

[0032] The technical solution of the present invention will be further described below with reference to the drawings and examples.

[0033] Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs.

[0034] Example 1

[0035] A bimetal element-doped CCTO modified dielectric ceramic material, and its preparation method includes the following steps:

[0036] S1. Add calcium nitrate tetrahydrate to deionized water, cover it with plastic wrap, and stir on a magnetic stirrer for 20 min to obtain a colorless transparent solution A; add copper nitrate trihydrate to absolute ethanol, cover it with plastic wrap, and stir on a magnetic stirrer for 20 min to obtain a blue transparent solution B; add tetrabutyl titanate to absolute ethanol, cover it with plastic wrap, and stir on a magnetic stirrer for 20 min to obtain a light yellow solution C; add zinc nitrate hexahydrate to deionized water, cover it with plastic wrap, and stir on a magnetic stirrer for 20 min to obtain a colorless transparent solution D; add zirconium oxynitrate to absolute ethanol, cover it with plastic wrap, and stir on a magnetic stirrer for 20 min to obtain a colorless transparent solution E.

[0037] S2. Pour solution A into the continuously stirred solution C, wash the beaker of solution A three times with glacial acetic acid, and pour all the washing liquids into the mixed solution of solution A and solution C. Repeat the above operation for the pouring of solution B, solution D, and solution E. Finally, a precursor solution is obtained, and the molar ratio of Ca, Cu, Zn, Ti, and Zr in the precursor solution is 1:2.975:0.025:3.95:0.05.

[0038] S3. Use 65% concentrated nitric acid to adjust the pH value of the precursor solution to 1.37, cover it with plastic wrap to prevent the solution from volatilizing. After magnetic stirring for 2 h, a light blue solution is obtained, and after aging at room temperature for 72 h, a light blue jelly-like CCTO colloid is obtained.

[0039] S4. Dry the CCTO colloid in a vacuum oven at 80 °C for 96 h to obtain a blue-green xerogel, and put the xerogel into a ball mill to grind it into a blue-green powder.

[0040] S5. Put the ball-milled powder into a corundum crucible that has been washed with anhydrous ethanol and dried, and sinter it in a muffle furnace. First, raise the temperature from room temperature to 350 °C at a heating rate of 5 °C / min, hold for 3 h, then raise the temperature to 900 °C, hold for 10 h, and cool to room temperature to obtain a brownish powder F.

[0041] S6. Mix the powder F evenly with 5% PVA binder, and use a tablet press to press tablets. The pressure of the tablet press is 10 MPa to obtain dark brown and smooth-surfaced round tablets.

[0042] S7. Anneal the round tablets in a muffle furnace. First, raise the temperature to 300 °C, hold for 1 h, then raise the temperature to 700 °C, hold for 1 h, and finally raise the temperature to 900 °C, hold for 6 h. After cooling to room temperature, obtain CaCu 2.975 Zn 0.025 Ti 3.95 Zr 0.05 O 12 ceramic material.

[0043] Example 2

[0044] The difference between Example 2 and Example 1 is that in Example 2, the molar ratio of Ca, Cu, Zn, Ti, and Zr in the precursor solution is 1:2.95:0.05:3.95:0.05, and CaCu 2.95 Zn 0.05 Ti 3.95 Zr 0.05 O 12 ceramic material is obtained.

[0045] Example 3

[0046] The difference between Example 3 and Example 1 is that in Example 3, the molar ratio of Ca, Cu, Zn, Ti, and Zr in the precursor solution is 1:2.925:0.075:3.95:0.05, and CaCu 2.925 Zn 0.075 Ti 3.95 Zr 0.05 O 12 ceramic material is obtained.

[0047] Example 4

[0048] The difference between Example 4 and Example 1 is that in Example 4, the molar ratio of Ca, Cu, Zn, Ti, and Zr in the precursor solution is 1:2.9:0.1:3.95:0.05, and CaCu 2.9 Zn 0.1 Ti 3.95 Zr 0.05 O 12Ceramic material.

[0049] Example 5

[0050] The difference between Example 5 and Example 1 is that: the specific steps of S7 in Example 5 are as follows: anneal the wafer in a muffle furnace, first heat up to 300 °C, hold for 1 h, then heat up to 700 °C, hold for 1 h, and finally heat up to 1000 °C, hold for 6 h. After cooling to room temperature, CaCu with an annealing temperature of 1000 °C is obtained. 2.975 Zn 0.025 Ti 3.95 Zr 0.05 O 12 Ceramic material.

[0051] Example 6

[0052] The difference between Example 6 and Example 2 is that: the specific steps of S7 in Example 6 are as follows: anneal the wafer in a muffle furnace, first heat up to 300 °C, hold for 1 h, then heat up to 700 °C, hold for 1 h, and finally heat up to 1000 °C, hold for 6 h. After cooling to room temperature, CaCu with an annealing temperature of 1000 °C is obtained. 2.95 Zn 0.05 Ti 3.95 Zr 0.05 O 12 Ceramic material.

[0053] Example 7

[0054] The difference between Example 7 and Example 3 is that: the specific steps of S7 in Example 7 are as follows: anneal the wafer in a muffle furnace, first heat up to 300 °C, hold for 1 h, then heat up to 700 °C, hold for 1 h, and finally heat up to 1000 °C, hold for 6 h. After cooling to room temperature, CaCu with an annealing temperature of 1000 °C is obtained. 2.925 Zn 0.075 Ti 3.95 Zr 0.05 O 12 Ceramic material.

[0055] Example 8

[0056] The difference between Example 8 and Example 4 is that: the specific steps of S7 in Example 8 are as follows: anneal the wafer in a muffle furnace, first heat up to 300 °C, hold for 1 h, then heat up to 700 °C, hold for 1 h, and finally heat up to 1000 °C, hold for 6 h. After cooling to room temperature, CaCu with an annealing temperature of 1000 °C is obtained. 2.9 Zn 0.1 Ti 3.95 Zr 0.05 O 12 Ceramic material.

[0057] Test 1

[0058] The ceramic materials with an annealing temperature of 900 °C prepared in Examples 1-4 were subjected to XRD testing, and the results are as Figure 1 shown. It can be seen from Figure 1 that for ceramic samples with different Zn 2+ doping amounts, there are strong peaks at the (220), (400), and (422) crystal planes corresponding to the strong peaks of the CCTO standard card, and the characteristic peaks of different Zn 2+ doping amounts are shifted compared to the standard spectrum, indicating that changing the doping amount of metal elements affects the crystal microstructure.

[0059] Test 2

[0060] The surfaces of the ceramic materials prepared in Examples 1-8 were polished, and conductive silver paste was applied to both poles of the ceramic materials. After welding wires at both ends, electrical property testing was carried out.

[0061] Figure 2 is a graph showing the variation of the dielectric constant with frequency for the ceramic materials with an annealing temperature of 900 °C prepared in Examples 1-4, Figure 3 and is a graph showing the variation of the dielectric constant with frequency for the ceramic materials with an annealing temperature of 1000 °C prepared in Examples 5-8. It can be seen from Figure 2 and Figure 3 that the dielectric constant decreases with increasing frequency. When the annealing temperature increases from 900 °C to 1000 °C, the dielectric constant decreases significantly. Moreover, at the same annealing temperature, with the increase in the Zn 2+ doping amount, the dielectric constant also shows a downward trend, but the ceramic materials still exhibit giant dielectric properties.

[0062] Figure 4 is a graph showing the variation of the dielectric loss with frequency for the ceramic materials with an annealing temperature of 900 °C prepared in Examples 1-4, Figure 5 and is a graph showing the variation of the dielectric loss with frequency for the ceramic materials with an annealing temperature of 1000 °C prepared in Examples 5-8. It can be seen from Figure 4 and Figure 5 that the dielectric loss shows a trend of first decreasing and then increasing with increasing frequency, and there are obvious differences in the dielectric losses of ceramic materials treated with different Zn 2+ doping amounts and different annealing temperatures. For CaCu 2+ Zn 2.9 Zn 0.1 Ti 3.95 Zr 0.05 O 12The ceramic material has a minimum dielectric loss D = 0.002 at 100 Hz, its dielectric constant K = 1270. In addition, it has a small and stable dielectric loss in a wide frequency range, always remaining at a low level, and the frequency dependence of the dielectric loss is well regulated.

[0063] Therefore, the present invention adopts the above-mentioned dielectric ceramic material modified by doping CCTO with a double metal element and its preparation method, which can effectively reduce the dielectric loss, maintain a high dielectric constant, improve the frequency dependence of CCTO, and keep the dielectric properties in a wide frequency range efficient and stable.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A bimetallic element doped CCTO modified dielectric ceramic material, characterized in that: The chemical formula of CCTO modified dielectric ceramic material doped with bimetallic elements is CaCu 3-x Zn x Ti 3.95 Zr 0.05 O 12 ; Among them, 0 <x<3。 2. The method for preparing a bimetallic element doped CCTO modified dielectric ceramic material according to claim 1, characterized in that: The following steps are involved: S1. Calcium nitrate tetrahydrate, copper nitrate trihydrate, tetrabutyl titanate, zinc nitrate hexahydrate and zirconium oxynitrate are mixed with a solvent respectively, covered with plastic wrap and stirred to obtain solution A, solution B, solution C, solution D and solution E; S2, mixing solution A, solution B, solution C, solution D and solution E to obtain a precursor solution; S3, adjusting the pH of the precursor solution with concentrated nitric acid, and obtaining CCTO colloid after stirring and aging; S4, drying the CCTO colloid in a vacuum oven to obtain a dry gel, and grinding the dry gel into powder in a ball mill; S5, placing the ball-milled powder into a muffle furnace for sintering, and obtaining powder F after cooling to room temperature; S6, mixing powder F and PVA adhesive evenly, and pressing them into tablets using a tablet press to obtain round tablets with smooth surfaces; S7, annealing the wafer in a muffle furnace, and cooling it to room temperature to obtain CaCu 3-x Zn x Ti 3.95 Zr 0.05 O 12 Ceramic material.

3. The preparation method according to claim 2, characterized in that: In S1, the solvent is one of deionized water and anhydrous ethanol; The solvents of solution A and solution D were both deionized water; The solvents of solution B, solution C and solution D are all anhydrous ethanol.

4. The preparation method according to claim 2, characterized in that: In S1, the stirring time is 10-30 min.

5. The preparation method according to claim 2, characterized in that: In S2, the molar ratio of Ca, Cu, Zn, Ti and Zr in the precursor solution is 1:(2.9-2.975):(0.025-0.1):3.95:0.

05.

6. The preparation method according to claim 2, characterized in that: In S3, the concentration of concentrated nitric acid is 60-70%, the pH value of the precursor solution is adjusted to 1-2, the stirring time is 1-3 hours, and the aging time is 36-72 hours.

7. The preparation method according to claim 2, characterized in that: In S4, the drying temperature is 80-100°C and the drying time is 48-96h.

8. The preparation method according to claim 2, characterized in that: In S5, the specific operation of sintering is: heating from room temperature to 350-400°C at a heating rate of 5-10°C / min, keeping the temperature for 3-4h, and then heating to 900-950°C, keeping the temperature for 10-12h.

9. The preparation method according to claim 2, characterized in that: In S6, the concentration of the PVA adhesive is 3-7%.

10. The preparation method according to claim 2, characterized in that: In S7, the specific operation of the annealing treatment is: firstly heating to 300-350°C, keeping the temperature for 1-2 hours, then heating to 700-750°C, keeping the temperature for 1-2 hours, and finally heating to 900-1000°C, keeping the temperature for 4-6 hours.

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