Zirconium-cerium composite ion modified sodium bismuth titanate-based dielectric energy storage ceramic material and preparation method thereof

Abstract

The invention discloses a zirconium-cerium composite ion modified sodium bismuth titanate-based dielectric energy storage ceramic material and a preparation method thereof, the chemical general formula of the ceramic material is (Bi < 0.5 > Na < 0.5 >) < 0.65 > (Ba < 0.3 > Sr < 0.7 >) < 0.35 > Ti < 1-x > (Zr < 0.8 > Ce < 0.2 >) < x > O < 3 >, and x is greater than or equal to 0.01 and less than or equal to 0.12. The composite ion (Zr0. 8Ce0. 2) < 4 + > is introduced to equivalently replace Ti < 4 + > ions at the B site in (Bi0. 5Na0. 5) 0.65 (Ba0. 3Sr0. 7) 0.35 TiO3, so that the density of crystal grains is effectively improved, the breakdown field strength of the ceramic is remarkably improved, a slender ferroelectric hysteresis loop is obtained, and excellent energy storage performance and dielectric temperature stability are obtained under a low electric field. According to the invention, the difficulty of low energy storage density under a low electric field is broken through, the preparation process is simple and easy to operate, the performance stability is better, and the development requirements of miniaturization and integration of current electronic products are met.

Description

Technical Field

[0001] The invention relates to the technical field of lead-free dielectric energy storage ceramic materials, and in particular to a zirconium-cerium composite ion modified sodium bismuth titanate-based dielectric energy storage ceramic material and a preparation method thereof. Background Art

[0002] In order to promote the sustainable, green and high-quality development of energy utilization, many new power generation methods (such as tidal energy, wind energy, solar energy, etc.) have been developed so far. New green energy not only meets human demand for energy, but also greatly reduces the impact on the environment. However, the utilization of this new energy has many problems such as low conversion efficiency and inconvenient storage. Therefore, it is imperative to research and develop efficient energy storage technology. Compared with other energy storage materials, such as batteries, electrochemical capacitors and fuel cells, dielectric capacitors have the unique characteristics of ultra-high power density and ultra-fast discharge rate. Compared with other energy storage devices in high pulse power systems, they are very competitive. Dielectric capacitors play an increasingly important role in electronic equipment and power systems and have become a global hotspot. However, the relatively low energy storage density of dielectric capacitors hinders their wider application. Therefore, current research is mainly focused on the development of dielectrics with higher energy storage density and good stability to meet the development requirements of miniaturization, integration, high capacity and high reliability.

[0003] Na 0.5 Bi 0.5 TiO3 (BNT)-based lead-free ferroelectric materials have a high saturation polarization intensity P at room temperature due to the hybridization between Bi 6s and O 2p orbitals (i.e., lone pair effect) to form lone electron pairs. s (>40μC / cm 2 ). Therefore, it is considered to be one of the most promising substrates for designing lead-free relaxation energy storage materials, but the large remnant polarization P r (38μC / cm 2 ) and a larger coercive electric field (E c ) greatly reduces the releasable energy storage density (W rec ) and energy storage efficiency (η).

[0004] Low breakdown field strength, high remnant polarization, and poor dielectric temperature stability greatly limit the application of BNT-based lead-free energy storage ceramics. Therefore, it is necessary to improve the breakdown field strength while maintaining a large polarization difference (P s -P r ) and good temperature stability, which is of great significance for the widespread application of lead-free energy storage ceramics. Summary of the invention

[0005] The object of the present invention is to overcome the deficiencies of the prior art and provide a sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions. By using composite equivalent ions (Zr 0.8 Ce 0.2 ) 4+ to replace Ti 4+ ions for doping modification, the breakdown field strength of the ceramic is significantly improved, and excellent energy storage performance and dielectric temperature stability are obtained under low electric fields. Another object of the present invention is to provide a preparation method for the above-mentioned sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] A sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions provided by the present invention uses composite equivalent ions (Zr 0.8 Ce 0.2 ) 4+ to replace Ti 0.5 ions at the B-site in (Bi 0.5 ) 0.65 (Ba 0.3 Sr 0.7 ) 0.35 TiO3, forming a chemical general formula of (Bi 4+ ) 0.5 Na 0.5 ) 0.65 (Ba 0.3 Sr 0.7 ) 0.35 Ti (1-x) (Zr 0.8 Ce 0.2 ) x O3, where 0.01 ≤ x ≤ 0.12.

[0008] In the above solution, the effective energy storage density of the dielectric energy storage ceramic material of the present invention under a low electric field of 210 kV / cm ≥ 2.97 J / cm 3 and the energy storage efficiency ≥ 80.5%, and the dielectric constant in the temperature range of 18 - 257 °C is 2967 ± 15%.

[0009] Another object of the present invention is achieved by the following technical solutions:

[0010] The preparation method for the above-mentioned sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions provided by the present invention includes the following steps:

[0011] (1) Bi2O3, Na2CO3, TiO2, BaCO3, SrCO3, CeO2, and ZrO2 are used as raw materials, the ingredients are prepared according to the chemical formula, and then anhydrous ethanol is used as a ball milling medium for ball milling and mixing to obtain a slurry;

[0012] (2) The slurry is sieved, dried, pressed and shaped, and pre-fired at 750-900°C for 3-6 hours, cooled to room temperature, and ground to obtain pre-fired powder.

[0013] (3) subjecting the pre-sintered powder to a secondary ball milling treatment, followed by drying, grinding, granulating, aging, and pressing to obtain a ceramic body;

[0014] (4) After the ceramic body is subjected to binder removal treatment, alumina is used as calcining powder and calcined at a temperature of 1160-1280° C. for 2-6 hours. After natural cooling, a zirconium-cerium composite ion-modified sodium bismuth titanate-based dielectric energy storage ceramic material is obtained.

[0015] Furthermore, in the preparation method of the present invention, the rotation speed of the first ball milling in step (1) is 300-500 rpm, and the ball milling time is 10-24 hours. In step (2), the pressing molding is carried out under a pressure of 4-6 MPa. In step (3), the rotation speed of the second ball milling is 300-500 rpm, and the ball milling time is 12-36 hours; the pressing molding is carried out under a pressure of 100-200 MPa. In step (4), the debinding treatment is carried out at a temperature of 600-800°C.

[0016] The present invention has the following beneficial effects:

[0017] (1) The present invention is achieved by 0.5 Na 0.5 ) 0.65 (Ba 0.3 Sr 0.7 ) 0.35 TiO3 system (Zr 0.8 Ce 0.2 ) 4+ Replace Ti 4+ , effectively destroying the long-range ordered ferroelectric domains, delaying polarization saturation, improving relaxivity, effectively improving the density of grains, significantly improving the breakdown field strength, obtaining a slender hysteresis loop, and obtaining excellent energy storage density and energy storage efficiency under low electric field, and having excellent dielectric stability in an ultra-wide temperature range (18-257°C).

[0018] (2) The present invention overcomes the difficulty of low energy storage density under low electric fields, has a simple process, is easy to prepare, all raw materials do not contain lead, are environmentally friendly, do not contain rare earth elements and precious metals, have a low production cost, have good performance stability, are suitable for mass production, and can meet the development needs of miniaturization and integration of current electronic products. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described in detail below in conjunction with embodiments and drawings:

[0020] Figure 1 It is the XRD pattern of the dielectric energy storage ceramic materials prepared in the examples and comparative examples of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] A preparation method of a zirconium-cerium composite ion modified sodium bismuth titanate-based dielectric energy storage ceramic material according to an embodiment of the present invention is as follows:

[0022] (1) Using Bi2O3 (purity 99.0%), Na2CO3 (purity 99.8%), TiO2 (purity 98.0%), BaCO3 (purity 99.0%), SrCO3 (purity 99.0%), CeO2 (purity 99.8%), ZrO2 (purity 99.0%) as raw materials, according to the stoichiometric ratio of the chemical general formula (Bi 0.5 Na 0.5 ) 0.65 (Ba 0.3 Sr 0.7 ) 0.35 Ti (1-x) (Zr 0.8 Ce 0.2 ) x O3 for batching, then using zirconia ball mills and anhydrous ethanol as the ball milling medium for primary ball milling and mixing, with a ball milling speed of 500 revolutions / min and a ball milling time of 15 h to obtain a slurry;

[0023] (2) After the above slurry is sieved, it is dried in an oven at 80 °C for 48 h to fully volatilize ethanol, then pressed into a shape under a pressure of 5 MPa, placed in a sealed crucible and subjected to a pre-sintering treatment at a temperature of 870 °C, kept warm for 3.5 h, and cooled to room temperature with the furnace, and then ground to obtain pre-sintered powder;

[0024] (3) Conduct a secondary ball milling treatment on the above pre-sintered powder, with a ball milling speed of 500 revolutions / min and a ball milling time of 24 h; grind the powder obtained after drying the resulting slurry in an oven at 80 °C for 12 h until it is uniform and does not agglomerate; then add PVA with a concentration of 6% for granulation, pass through an 80-mesh sieve and age for 24 h to obtain powder particles; uniformly place the powder particles into a mold and press them into a shape under a pressure of 120 MPa to obtain a ceramic green body;

[0025] (4) The above-mentioned ceramic green body is subjected to a debinding treatment by holding at 700 °C for 30 min to fully discharge the PVA in the ceramic green body; then, using alumina as the buried firing powder, it is subjected to a buried firing treatment at 1240 °C for a holding time of 2 h, and after natural cooling, a zirconium-cerium composite ion-modified sodium bismuth titanate-based dielectric energy storage ceramic material is obtained.

[0026] The chemical general formulas of the embodiments of the present invention are shown in Table 1.

[0027] Using Bi2O3 (purity 99.0%), Na2CO3 (purity 99.8%), TiO2 (purity 98.0%), BaCO3 (purity 99.0%), SrCO3 (purity 99.0%) as raw materials, according to the chemical formula (Bi 0.5 Na 0.5 ) 0.65 (Ba 0.3 Sr 0.7 ) 0.35 TiO3 for the stoichiometric ratio for batching as a comparative example, and other process conditions are the same as those of the embodiments of the present invention.

[0028] As Figure 1 shown, the dielectric energy storage ceramic materials prepared in the embodiments of the present invention all exhibit a typical perovskite phase structure and no second phase is generated, indicating that Zr 4+ and Ce 4+ ions have uniformly entered (Bi 0.5 Na 0.5 ) 0.65 (Ba 0.3 Sr 0.7 ) 0.35 TiO3 lattice to form a solid solution.

[0029] The effective energy storage density and energy storage efficiency of the dielectric energy storage ceramic materials prepared in the embodiments of the present invention and the comparative examples are shown in Table 1.

[0030] Table 1 Chemical general formulas of the embodiments of the present invention and comparative examples and performance indexes of their dielectric energy storage ceramic materials

[0031]

Claims

1. A sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions, characterized in that: With a composite equivalent ion (Zr 0.8 Ce 0.2 ) 4+ substituting for (Bi 0.5 Na 0.5 ) 0.65 (Ba 0.3 Sr 0.7 ) 0.35 the Ti 4+ ion at the B-site in TiO3, the chemical general formula formed is (Bi 0.5 Na 0.5 ) 0.65 (Ba 0.3 Sr 0.7 ) 0.35 Ti (1-x) (Zr 0.8 Ce 0.2 ) x O3, where 0.01 ≤ x ≤ 0.

12.

2. The sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions according to claim 1, characterized in that: The effective energy storage density of the dielectric energy storage ceramic material under a low electric field of 210 kV / cm is ≥ 2.97 J / cm 3 , the energy storage efficiency is ≥ 80.5%, and the dielectric constant in the temperature range of 18 - 257 °C is 2967 ± 15%.

3. The preparation method of the sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions according to claim 1 or 2, characterized in that It includes the following steps: (1) Using Bi2O3, Na2CO3, TiO2, BaCO3, SrCO3, CeO2, and ZrO2 as raw materials, after batching according to the chemical general formula, using anhydrous ethanol as the ball-milling medium for primary ball-milling and mixing to obtain a slurry; (2) After sieving and drying the slurry, it is pressed into shape and subjected to pre-sintering treatment at 750 - 900 °C, holding for 3 - 6 h, cooling to room temperature with the furnace, and obtaining pre-sintered powder after grinding; (3) After secondary ball-milling treatment of the pre-sintered powder, it is dried, ground, granulated, aged, and pressed into shape to obtain a ceramic green body; (4) After the ceramic green body is subjected to debinding treatment, using alumina as the buried firing powder, it is subjected to buried firing treatment at a temperature of 1160 - 1280 °C, with a holding time of 2 - 6 h. After natural cooling, a sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions is obtained.

4. The preparation method of the bismuth sodium titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions according to claim 3, characterized in that: In the step (1), the rotation speed of the primary ball-milling is 300 - 500 r / min, and the ball-milling time is 10 - 24 h.

5. The preparation method of the sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions according to claim 3, characterized in that: In the step (2), it is pressed into shape under a pressure of 4 - 6 MPa.

6. The preparation method of the sodium bismuth titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions according to claim 3, characterized in that: In the step (3), the rotation speed of the secondary ball-milling is 300 - 500 r / min, and the ball-milling time is 12 - 36 h; it is pressed into shape under a pressure of 100 - 200 MPa.

7. The preparation method of the bismuth sodium titanate-based dielectric energy storage ceramic material modified by zirconium-cerium composite ions according to claim 3, characterized in that: In the step (4), the debinding treatment is carried out at a temperature of 600 - 800 °C.

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