Bi with high temperature stability and high energy storage properties 3+ Doped sodium bismuth titanate-based lead-free ferroelectric ceramic material and preparation method thereof

Abstract

The invention discloses a Bi with high temperature stability and high energy storage characteristics 3+ Doped sodium bismuth titanate-based lead-free ferroelectric ceramic material and preparation method thereof, the structural formula of the ceramic material is 0.5(0.93Bi 0.5 Na 0.5 TiO3‑0.07CaSnO3)‑0.5Sr 1‑ 1.5x Bi x TiO3, wherein the value of x is 0.12 to 0.30, is prepared by batching, ball milling, pre-sintering, secondary ball milling, screening, tableting, and sintering. The preparation method of the present invention is simple, low in cost, good in repeatability, and high in yield. The obtained ceramic material has high energy storage density and high temperature stability. When x=0.20, its effective energy storage density is 4.02 J / cm 3 , the energy storage efficiency can reach 80.2%. The ceramic material of the present invention has higher temperature stability and energy storage characteristics, and is expected to provide a new alternative material in the field of pulse power systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic materials, and specifically relates to a Bi 3+ Doped sodium bismuth titanate-based lead-free ferroelectric ceramic material and preparation method thereof. Background Art

[0002] Energy is the material cornerstone of human existence and development. With the rapid development of industrial production, the demand for miniaturization and integration of electronic devices is growing. The complexity of the working environment in the application field has put forward more stringent requirements on the dielectric temperature stability. Therefore, the research and development of lead-free energy storage ceramic materials with both high temperature stability and high energy storage characteristics has important practical application significance. 0.5 Na 0.5 TiO 3 Lead-free ferroelectric ceramics have Bi 3+ With Pb 2+ It has the same outermost electron structure as lead-based energy storage ceramics and is considered to be the best candidate material to replace lead-based energy storage ceramics. At the same time, its high Curie temperature and the double dielectric peak structure in the dielectric temperature spectrum make it possible to obtain good dielectric temperature stability in a relatively wide temperature range. However, there is still little research on energy storage ceramic materials with high energy storage characteristics and temperature stability.

[0003] How to achieve the comprehensive improvement of temperature stability and energy storage characteristics in sodium bismuth titanate (BNT)-based lead-free ferroelectric ceramic materials is a hot issue that needs to be solved urgently. CN 113735578 B discloses a sodium bismuth titanate-based lead-free ferroelectric ceramic material with high dielectric temperature stability and energy storage characteristics and a preparation method thereof, namely (1-x)Bi 0.5 Na 0.5 TiO 3 -xCaSnO 3 Ceramic materials, when x = 0.15, in the temperature range of -94 ~ 500 ℃, the temperature change rate meets TCC 150℃ ≤±15%, good temperature stability, but only 1.1J / cm 3 At the same time, QYZhou et al. (Achieving high comprehensive energy storage properties of BNT-based ceramics via multiscale regulation, Ceram. Int. 49 (2023) 19701-19707.) introduced the multi-scale regulation of BNT-based ceramics to achieve comprehensive energy storage performance improvement, namely (1-x) (0.93Bi 0.5 Na 0.5 TiO3 -0.07CaSnO 3 )-xSrTiO 3 Ceramic material, when x = 0.5, has 4.2 J / cm 3 The effective energy storage density and energy storage efficiency of 88% are achieved, but its temperature stability is poor. The use requirements of medium and high temperature working environments force the ceramic materials with high temperature stability and energy storage performance to be further explored and have important research potential. Summary of the invention

[0004] The purpose of the present invention is to solve (1-x)(0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-xSrTiO 3 The problem of poor temperature stability of ceramic materials is solved by providing a Bi with high temperature stability and high energy storage characteristics. 3+ The invention discloses a lead-free ferroelectric ceramic material based on sodium bismuth titanate, and provides a preparation method thereof with simple process, good repeatability and low cost.

[0005] For the above purpose, the structural formula of the ceramic material used in the present invention is 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 , wherein the value of x is 0.12 to 0.30, and the preferred value of x is 0.20.

[0006] The present invention 3+ The preparation method of the doped sodium bismuth titanate-based lead-free ferroelectric ceramic material comprises the following steps:

[0007] Step 1: According to 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 The stoichiometric ratio is 98.00% or higher, and CaCO 3 、TiO 2 、Na 2 CO 3 、Bi 2 O 3 SnO 2 、SrCO 3, all the weighed raw materials are mixed evenly and put into a nylon jar, zirconium balls are used as grinding balls and anhydrous ethanol is used as ball milling medium, the mixture is fully mixed and ball milled for 20 to 24 hours, and dried at 60 to 80° C. for 20 to 24 hours to obtain a raw material mixture;

[0008] Step 2: Pre-calcine the raw material mixture at 850-950°C for 2-4 hours, and then perform secondary ball milling, drying, and sieving to obtain 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 mixture;

[0009] Step 3: Substitute the 0.5(0.93Bi obtained in step 2 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 After the mixture is pressed into tablets, it is sintered at a constant temperature of 1000-1210°C for 2-4 hours and then naturally cooled to room temperature to prepare Bi 3+ Doped sodium bismuth titanate based lead-free ferroelectric ceramic materials.

[0010] In the above step 2, the raw material mixture is pre-calcined at 850-950°C for 2-4 hours, the obtained pre-calcined powder is put into a nylon jar, fully mixed and ball-milled for 20-24 hours, dried at 60-80°C for 12-24 hours, ground with a mortar, and passed through a 180-200 mesh sieve.

[0011] In the above step 3, the tablet is pressed into a cylindrical blank by a powder tablet press, and then cold isostatically pressed at a pressure of 150 to 200 MPa for 5 to 7 minutes, and then the cylindrical blank after cold isostatic pressing is placed on a zirconia flat plate, and the zirconia flat plate is placed in an alumina closed sagger, and the temperature is increased at a rate of 2 to 5°C / min to 1100 to 1210°C, and sintered at a constant temperature for 2 to 4 hours.

[0012] In the above step 3, the temperature is preferably increased to 1170° C. at a heating rate of 3° C. / min and sintered for 3 hours.

[0013] The beneficial effects of the present invention are as follows:

[0014] 1. The present invention selects 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3)-0.5SrTiO 3 A-site Bi 3+ Replace, through Bi 3+ The introduction of Bi inhibits grain growth, reduces grain size and pore count, increases the density of ceramics, and thus increases the breakdown field strength of ceramic materials. 3+ The introduction of makes the ceramic gradually transform from a normal ferroelectric to a relaxor ferroelectric, and the Curie temperature moves toward room temperature, which helps to obtain an elongated PE curve, and ultimately obtain an energy storage ceramic material with both high energy storage density and high energy storage efficiency.

[0015] 2. In the preparation process of ceramic materials, the present invention adopts advanced cold isostatic pressing technology, which avoids sample waste, saves the cost of adhesives and subsequent debinding processes, and shortens the preparation cycle of ceramics; at the same time, the cold isostatic pressing has high density, uniform density, and low stress in the body, which reduces defects such as cracking and delamination of the body, which provides a guarantee for the quality of the ceramics and lays a foundation for excellent experimental results. In addition, the raw materials selected by the present invention do not contain heavy metals such as lead, are environmentally friendly, have higher energy storage performance and good temperature stability, and provide a new alternative material solution for the development of lead-free ferroelectric ceramic materials with high temperature stability and high energy storage characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The sodium bismuth titanate-based lead-free ferroelectric ceramic material prepared in Comparative Example 1 and the Bi 3+ XRD pattern of sodium bismuth titanate-doped lead-free ferroelectric ceramic material.

[0017] Figure 2 Graphs showing the dielectric constant and dielectric loss of the sodium bismuth titanate-based lead-free ferroelectric ceramic material prepared in Comparative Example 1 at different test frequencies.

[0018] Figure 3 is Bi prepared in Example 3 3+ Dielectric constant and dielectric loss diagram of doped sodium bismuth titanate-based lead-free ferroelectric ceramic materials at different test frequencies.

[0019] Figure 4 Bi prepared in Comparative Example 1 and Examples 1 to 3 3+ Δε / ε of lead-free ferroelectric ceramic materials based on sodium bismuth titanate doped at 1kHz 150℃ Curve that changes with temperature T.

[0020] Figure 5 The sodium bismuth titanate-based lead-free ferroelectric ceramic material prepared in Comparative Example 1 and the Bi 3+ Unipolar hysteresis loop diagram of sodium bismuth titanate-doped lead-free ferroelectric ceramic material under critical breakdown electric field.

[0021] Figure 6 The sodium bismuth titanate-based lead-free ferroelectric ceramic material prepared in Comparative Example 1 and the Bi 3+ Comparison of the effective energy storage density and energy storage efficiency of sodium bismuth titanate-doped lead-free ferroelectric ceramic materials under the critical breakdown electric field. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0023] Comparative Example 1

[0024] Step 1: According to 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5SrTiO 3 The chemical stoichiometry was 1.1562 g of Na with a purity of more than 98.00%. 2 CO 3 5.0845g Bi 2 O 3 、6.9280g TiO 2 , and 0.3112g CaCO with a purity of more than 99.00% 3 , 0.4667g SnO 2 , 6.5310g SrCO 3 All the weighed raw materials were mixed evenly and put into a nylon jar, and milled for 24 hours in a ball mill with a rotation speed of 401 rpm using zirconium balls as grinding balls and anhydrous ethanol as ball milling media. The mixture was dried at 80°C for 24 hours and ground in a mortar for 30 minutes to obtain a raw material mixture.

[0025] Step 2: Place the raw material mixture of step 1 in an alumina crucible, compact it with an agate rod, cover it, place it in a resistance furnace, heat it to 950℃ at a heating rate of 3℃ / min, pre-sinter it for 3 hours, cool it naturally to room temperature, remove it from the furnace, grind it with a mortar to obtain pre-sintered powder. Put the pre-sintered powder into a nylon jar, mix it thoroughly, ball mill it for 24 hours, dry it at 80℃ for 12 hours, grind it with a mortar, pass it through a 180 mesh sieve, and obtain 0.5(0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5SrTiO 3 mixture.

[0026] Step 3: Substitute the 0.5(0.93Bi obtained in step 2 0.5Na 0.5 TiO 3 -0.07CaSnO 3) -0.5SrTiO 3 The mixture was pressed into a cylindrical blank with a diameter of 11.5 mm and a thickness of 1.1 mm by a powder tablet press, and then cold isostatically pressed for 5 minutes at a pressure of 180 MPa. The cylindrical blank after cold isostatic pressing was placed on a zirconia plate, and the alumina plate was placed in an alumina closed sagger. The temperature was raised to 1170°C at a heating rate of 3°C / min, and the mixture was sintered at a constant temperature for 3 hours. The mixture was naturally cooled to room temperature with the furnace to prepare a 0.5(0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5SrTiO 3 Sodium bismuth titanate-based lead-free ferroelectric ceramic materials.

[0027] Example 1

[0028] In step 1 of this embodiment, according to 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 0.82 Bi 0.12 TiO 3 The chemical stoichiometry was 1.1526 g of Na with a purity of more than 98.00%. 2 CO 3 、6.3771gBi 2 O 3 、6.9068gTiO 2 , and 0.3103 g of CaCO with a purity of more than 99.00% 3 , 0.4653g SnO 2 5.3391gSrCO 3 The other steps are the same as those in Comparative Example 1, and the molecular formula is 0.5(0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 0.82 Bi 0.12 TiO 3 Bi 3+ Doped sodium bismuth titanate based lead-free ferroelectric ceramic materials.

[0029] Example 2

[0030] In step 1 of this embodiment, according to 0.5 (0.93Bi0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 0.7 Bi 0.2 TiO 3 The chemical stoichiometry was 1.1319 g Na with a purity of more than 98.00%. 2 CO 3 7.1189g Bi 2 O 3 、6.7827gTiO 2 , and 0.3047 g of CaCO with a purity of more than 99.00% 3 , 0.4569g SnO 2 4.7956 g SrCO 3 The other steps are the same as those in Comparative Example 1, and the molecular formula is 0.5(0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 0.7 Bi 0.2 TiO 3 Bi 3+ Doped sodium bismuth titanate based lead-free ferroelectric ceramic materials.

[0031] Example 3

[0032] In step 1 of this embodiment, according to 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 0.55 Bi 0.3 TiO 3 The chemical stoichiometry was 1.1474 g Na with a purity of more than 98.00%. 2 CO 3 、8.3013gBi 2 O 3 、6.8753gTiO 2 , and 0.3088g CaCO with a purity of more than 99.00% 3 , 0.4632g SnO 2 、3.5648gSrCO 3 The other steps are the same as those in Comparative Example 1, and the molecular formula is 0.5(0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO3 )-0.5Sr 0.55 Bi 0.3 TiO 3 Bi 3+ Doped sodium bismuth titanate based lead-free ferroelectric ceramic materials.

[0033] The Bi prepared in Examples 1 to 3 above 3+ The surfaces of the sodium bismuth titanate-doped lead-free ferroelectric ceramic material and the sodium bismuth titanate-doped lead-free ferroelectric ceramic material prepared in Comparative Example 1 were ground, polished, ultrasonically cleaned, and silver paste was applied to the upper and lower surfaces, respectively, and placed in a muffle furnace at 840°C for 30 minutes, and naturally cooled to room temperature. XRD testing was performed using a Japanese Rigaku MiniFlex600 diffractometer, and the structure and performance were characterized and tested using a DMS-2000 high-temperature dielectric impedance spectrometer produced by Bailibo Technology Co., Ltd. and a ferroelectric tester produced by Radiant, USA. The results are shown in Figures 1 to 6 .

[0034] Depend on Figure 1 It can be seen that all ceramics have perovskite structure. When x<0.12, no second phase is observed, indicating that the third component Sr 1-1.5x Bi x TiO 3 Completely dissolved in 0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 However, when x>0.2, there is an impurity phase in the XRD spectrum, and the impurity phase component is a titanium-rich region. 1-1.5x Bi x TiO 3 The introduction of Bi 2 Ti 2 O 7 The appearance of mixed phases. Figure 2 and Figure 3 Comparative Example 1 and Bi 3+ The dielectric temperature spectrum of Example 3 with the largest doping amount is shown in the test temperature range of -100 to 400°C. As can be seen from the figure, as Bi 3+ The increase in Bi content strengthens the relaxation behavior of the ceramic, the dielectric peak of the ceramic gradually weakens, and dielectric anomalies appear, which can be attributed to the "paraelectric-ferroelectric" phase transition. This phase transition originates from Bi 0.5 Na 0.5 TiO 3 sublattice, which leads to T m Move to higher temperatures at different rates. Figure 4 Display of ceramic material Δε / ε 150℃The curve graph of the change with temperature T generally believes that the change rate of the dielectric constant does not exceed 15%, which means that the dielectric constant of the ceramic material has good temperature stability. Figure 4 It can be seen that with Sr 1-1.5x Bi x TiO 3 The introduction of the dielectric constant of ceramic materials has significantly broadened the temperature stability range. When x = 0.00, TCC is within the temperature range of 90 to 199 ° C. 150℃ ≤±15%; when x=0.12, TCC in the temperature range of 80~212℃ 150℃ ≤±15%; when x=0.20, TCC in the temperature range of 11~230℃ 150℃ ≤±15%; when x=0.30, it has the widest temperature stability range, i.e. 22℃ to 302℃ (ΔT increases by 157%), showing good temperature stability and reducing the dependence of the dielectric constant on temperature. Figure 5 and Figure 6 The sodium bismuth titanate-based lead-free ferroelectric ceramic materials prepared in Comparative Example 1 and the Bi prepared in Examples 1 to 3 are respectively 3+ Comparison of the unipolar PE curve, effective energy storage density and energy storage efficiency of the lead-free ferroelectric ceramic material based on sodium bismuth titanate doped with sodium bismuth titanate under the critical breakdown electric field. Figure 5 It can be seen that with Bi 3+ With the increase of the content, the breakdown field strength of the ceramic material prepared in Example 2 is significantly improved. Figure 6 It can be seen that the effective energy storage density of the ceramic material prepared in Comparative Example 1 is 3.35 J / cm 3 , the energy storage efficiency is 82%, 3+ The energy storage density of the ceramic materials prepared in Examples 1 to 3 is improved, and the energy storage density is about 3.37 to 4.02 J / cm 3 ; and the energy storage efficiency is maintained at above 75%, and the energy storage efficiency is about 78% to 85%. 3+ When the doping amount is 0.20, the effective energy storage density of the ceramic is as high as 4.02J / cm 3 , the energy storage efficiency is as high as 80%. 3+ Doped sodium bismuth titanate-based lead-free ferroelectric ceramic materials have high temperature stability while maintaining or even improving energy storage characteristics, and are expected to become candidate materials for medium and high temperature energy storage ceramic capacitors.

Claims

1. A Bi with high temperature stability and high energy storage properties 3+ Doped sodium bismuth titanate-based lead-free ferroelectric ceramic materials, Features: The structural formula of the ceramic material is 0.5(0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 ,in x The value of is 0.12~0.30; The preparation method of the ceramic material comprises the following steps: Step 1: According to 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 The stoichiometric ratio of CaCO with a purity of more than 98.00% was weighed respectively. 3 、TiO 2 、Na 2 CO 3 、Bi 2 O 3 SnO 2 、SrCO 3 , all the weighed raw materials are mixed evenly and put into a nylon jar, zirconium balls are used as grinding balls and anhydrous ethanol is used as ball milling medium, the mixture is fully mixed and ball milled for 20 to 24 hours, and dried at 60 to 80° C. for 20 to 24 hours to obtain a raw material mixture; Step 2: Pre-calcine the raw material mixture at 850-950°C for 2-4 hours, perform secondary ball milling, drying and sieving to obtain 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 mixture; Step 3: Substitute the 0.5(0.93Bi obtained in step 2 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 The mixture is pressed into a cylindrical blank by a powder tablet press, and then cold isostatically pressed at a pressure of 150-200 MPa for 5-7 minutes, sintered at a constant temperature of 1000-1210°C for 2-4 hours, and naturally cooled to room temperature in the furnace to prepare Bi 3+ Doped sodium bismuth titanate based lead-free ferroelectric ceramic materials.

2. Bi with high temperature stability and high energy storage characteristics according to claim 1 3+ Doped sodium bismuth titanate-based lead-free ferroelectric ceramic materials, Features: x The value of is 0.

20.

3. A Bi with high temperature stability and high energy storage characteristics as claimed in claim 1 3+ Preparation method of sodium bismuth titanate-doped lead-free ferroelectric ceramic material. Features The preparation method comprises the following steps: Step 1: According to 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 The stoichiometric ratio of CaCO with a purity of more than 98.00% was weighed respectively. 3 、TiO 2 、Na 2 CO 3 、Bi 2 O 3 SnO 2 、SrCO 3 , all the weighed raw materials are mixed evenly and put into a nylon jar, zirconium balls are used as grinding balls and anhydrous ethanol is used as ball milling medium, the mixture is fully mixed and ball milled for 20 to 24 hours, and dried at 60 to 80° C. for 20 to 24 hours to obtain a raw material mixture; Step 2: Pre-calcine the raw material mixture at 850-950°C for 2-4 hours, perform secondary ball milling, drying and sieving to obtain 0.5 (0.93Bi 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 mixture; Step 3: Substitute the 0.5(0.93Bi obtained in step 2 0.5 Na 0.5 TiO 3 -0.07CaSnO 3 )-0.5Sr 1-1.5x Bi x TiO 3 After the mixture is pressed into tablets, it is sintered at a constant temperature of 1000-1210°C for 2-4 hours and then naturally cooled to room temperature to prepare Bi 3+ Doped sodium bismuth titanate based lead-free ferroelectric ceramic materials.

4. Bi with high temperature stability and high energy storage characteristics according to claim 3 3+ Preparation method of sodium bismuth titanate-doped lead-free ferroelectric ceramic material. Features: In step 2, the raw material mixture is pre-calcined at 850-950° C. for 2-4 hours, the pre-calcined powder obtained is put into a nylon jar, fully mixed and ball-milled for 20-24 hours, dried at 60-80° C. for 12-24 hours, ground with a mortar, and passed through a 180-200 mesh sieve.

5. Bi with high temperature stability and high energy storage characteristics according to claim 3 3+ Preparation method of sodium bismuth titanate-doped lead-free ferroelectric ceramic material. Features: In step 3, the cylindrical blank after cold isostatic pressing is placed on a zirconia flat plate, and the zirconia flat plate is placed in an alumina closed sagger, and the temperature is increased to 1100-1210° C. at a rate of 2-5° C. / min, and sintered at a constant temperature for 2-4 hours.

6. Bi with high temperature stability and high energy storage characteristics according to claim 5 3+ Preparation method of sodium bismuth titanate-doped lead-free ferroelectric ceramic material. Features: In step 3, the temperature is increased to 1170° C. at a heating rate of 3° C. / min and sintered at a constant temperature for 3 hours.

Images