NaNbO3 lead-free ceramic material with stable antiferroelectric phase as well as preparation method and application of NaNbO3 lead-free ceramic material

Abstract

The invention discloses a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase and a preparation method and application thereof.The preparation method comprises the steps that Na2CO3 and Nb2O5 raw materials are weighed according to the equal substance amount ratio and mixed to obtain a mixture, the mixture is subjected to ball milling and drying and then calcined for 3-4 h at the temperature of 750-900 DEG C, and a full ingredient is obtained; carrying out ball milling, drying and sieving on the whole ingredient again to form a sieved material; pressing and molding the sieved material to prepare a green body, heating the prepared green body to 1250-1350 DEG C at a speed of 2 DEG C / min in a box-type furnace, preserving heat for 120 minutes, then cooling to 500 DEG C at a speed of 5 DEG C / min, and finally cooling to room temperature along with the furnace to obtain the NaNbO3 lead-free ceramic material with the stable antiferroelectric phase. According to the NaNbO3 lead-free ceramic material disclosed by the invention, the lead-free ceramic material with a stable antiferroelectric phase is prepared by controlling the pre-sintering temperature, and the NaNbO3 lead-free ceramic material is simple in preparation process, low in material cost, green and environment-friendly, and becomes an important candidate material of a high-performance lead-free antiferroelectric ceramic material.

Description

Technical Field

[0001] The invention belongs to the technical field of functional materials, relates to lead-free ceramic materials, and specifically relates to a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase, a preparation method and an application thereof. Background Art

[0002] Antiferroelectric materials are widely used in a variety of high-tech fields because of their antiferroelectric-ferroelectric phase transition characteristics under the action of an external electric field. This phase transition phenomenon is closely related to the small energy difference between the antiferroelectric phase and the ferroelectric phase. This characteristic gives antiferroelectric materials unique physical properties, such as double hysteresis effect, large volume expansion and significant electrocaloric effect, which makes them have important application potential in capacitors, drives and solid-state refrigeration. However, most of the existing high-performance antiferroelectric ceramic materials are based on perovskite structures containing toxic lead, such as lead zirconate (PbZrO3). Although these lead-containing materials have excellent performance, they have gradually faced strict environmental regulations due to their potential environmental pollution and health risks.

[0003] Therefore, the development of lead-free antiferroelectric materials has become an important direction in the current field of materials science. Sodium niobate (NaNbO3) is considered to be one of the ideal lead-free antiferroelectric materials because it has good antiferroelectric properties and its perovskite structure exhibits a stable antiferroelectric phase under certain conditions. However, the energy difference between the antiferroelectric phase (P phase) and the ferroelectric phase (Q phase) of sodium niobate is too close, resulting in unstable antiferroelectric properties and difficulty in realizing its potential functional applications. Although studies have been conducted to improve the antiferroelectric stability of sodium niobate by adjusting the formula and process, there is currently a lack of an effective method to achieve a long-term stable antiferroelectric phase in lead-free ceramic materials.

[0004] In the sodium niobate system, improving the stability of its antiferroelectric phase by regulating its crystal structure, such as doping and temperature treatment, has become a research hotspot. In response to this problem, some studies have attempted to improve the performance of sodium niobate ceramics by optimizing the preparation process, adjusting the formula ratio, and improving the sintering process. However, these methods usually have certain technical difficulties, such as complex processes, high material costs, or poor environmental performance.

[0005] Therefore, how to prepare a lead-free sodium niobate ceramic material with a stable antiferroelectric phase and high performance while ensuring environmental protection has become a technical problem that needs to be solved urgently. The present invention is proposed in this context, aiming to provide a solution for preparing a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase by controlling key parameters in the preparation process, such as calcination temperature, ball milling time, etc. The material can not only avoid the use of toxic lead components while ensuring good antiferroelectric properties, but also has a low production cost and a simplified process flow, which meets the current technical requirements of green environmental protection. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase and a preparation method and application thereof.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a NaNbO3 lead-free ceramic material having a stable antiferroelectric phase comprises the following steps:

[0009] Step 1, weighing Na2CO3 and Nb2O5 raw materials according to the same molar ratio to obtain a mixture, ball milling and drying the mixture, and calcining it at 750-900°C for 3-4h to obtain a complete batch;

[0010] Step 2: ball-mill, dry and sieve all the ingredients again to form sieved material;

[0011] Step 3: Press the screened material into a green body, and heat the prepared green body to 1250-1350°C in a box furnace at 2°C / min and keep it for 120 minutes, then cool it to 500°C at 5°C / min and finally cool it to room temperature with the furnace to obtain NaNbO3 lead-free ceramic material with a stable antiferroelectric phase.

[0012] Preferably, the ball milling in step 1 is to mix the mixture, zirconium balls and anhydrous ethanol in a mass ratio of 1: (2-5): (0.8-1.5) and then ball mill for 12-24 hours.

[0013] Preferably, the ball milling in step 2 is to mix all ingredients, zirconium balls and anhydrous ethanol in a mass ratio of 1: (4.8-5.2): (0.8-1.2) and then ball mill for 24-36 hours.

[0014] Preferably, the drying in step 1 and step 2 is performed in an oven at 80° C. for 10 to 12 hours.

[0015] Preferably, the mesh size of the sieve in step 2 is 100 to 200 meshes.

[0016] Preferably, the compression molding in step three is to first maintain the pressure at 200-220 MPa for 3 minutes, then maintain the pressure at 190 MPa for 5 minutes, and finally release the pressure at 40 MPa / min.

[0017] The present invention also protects a NaNbO3 lead-free ceramic material having a stable antiferroelectric phase prepared by the method as described above and its application as an antiferroelectric ceramic.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] The present invention controls the calcination temperature range and adjusts the phase change behavior of NaNbO3 crystals, so that the grains of NaNbO3 ceramic materials can be refined, the dielectric loss of the material can be effectively reduced, and its mechanical strength and crack resistance can be improved. The fine grain structure can effectively reduce the critical size of the antiferroelectric phase, making the antiferroelectric properties of the material more significant, thereby improving its dielectric constant and nonlinear behavior, achieving the stability of the antiferroelectric phase in a wider temperature range, and adapting to a wider range of application environments; especially under high electric fields, the material exhibits strong resistance to electric fields and is not prone to structural damage or performance degradation caused by electric fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 XRD patterns of NaNbO3 lead-free ceramics prepared in Examples 5 to 8;

[0021] Figure 2 The Raman shift diagram of NaNbO3 prepared in Examples 5 to 8;

[0022] Figure 3 The relationship between the SEM images of the NaNbO3 antiferroelectric ceramics prepared in Examples 1 to 16 and the sintering temperature and calcining temperature;

[0023] Figure 4 The relationship between the temperature dependence of the dielectric constant and tangent loss of the NaNbO3 antiferroelectric ceramics prepared in Examples 1 to 16 and the sintering temperature and calcining temperature. DETAILED DESCRIPTION

[0024] The specific contents of the present invention are further explained in detail below in conjunction with embodiments.

[0025] Example 1

[0026] This embodiment provides a method for preparing a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase, comprising the following steps:

[0027] Step 1, weighing Na2CO3 and Nb2O5 raw materials according to the same molar ratio to obtain a mixture, taking the mixture, zirconium spherulite and anhydrous ethanol according to the mass ratio of 1:5:1, mixing them and ball milling them for 20 hours, drying them in an oven at 80°C for 12 hours, and then calcining them at 750°C for 3 hours to obtain a complete batch;

[0028] Step 2: Mix all ingredients, zirconium balls and anhydrous ethanol in a mass ratio of 1:4.8:1, ball mill for 24 hours, dry in an oven at 80°C for 12 hours, and pass through a 150-mesh sieve to form a sieved material;

[0029] Step 3: Maintain the pressure of the sieved material at 200 MPa for 3 minutes, then at 190 MPa for 5 minutes, and finally release the pressure at 40 MPa / min to form a green body. The prepared green body is heated to 1290°C at 2°C / min in a box furnace and kept warm for 120 minutes, then cooled to 500°C at 5°C / min and finally cooled to room temperature with the furnace to obtain NaNbO3 lead-free ceramic material with a stable antiferroelectric phase.

[0030] Example 2

[0031] Example 2 is basically the same as Example 1, except that the calcination temperature of the mixture in step 1 is 800°C.

[0032] Example 3

[0033] Example 3 is basically the same as Example 1, except that the calcination temperature of the mixture in step 1 is 850°C.

[0034] Example 4

[0035] Example 4 is basically the same as Example 1, except that the calcination temperature of the mixture in step 1 is 900°C.

[0036] Example 5

[0037] This embodiment provides a method for preparing a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase, comprising the following steps:

[0038] Step 1, weighing Na2CO3 and Nb2O5 raw materials according to the same molar ratio to obtain a mixture, taking the mixture, zirconium spherulite and anhydrous ethanol according to the mass ratio of 1:5:1, mixing them and ball milling them for 20 hours, drying them in an oven at 80°C for 12 hours, and then calcining them at 750°C for 3 hours to obtain a complete batch;

[0039] Step 2: Mix all ingredients, zirconium balls and anhydrous ethanol in a mass ratio of 1:4.8:1, ball mill for 24 hours, dry in an oven at 80°C for 12 hours, and pass through a 150-mesh sieve to form a sieved material;

[0040] Step 3: Maintain the pressure of the sieved material at 200 MPa for 3 minutes, then at 190 MPa for 5 minutes, and finally release the pressure at 40 MPa / min to form a green body. Heat the prepared green body to 1310°C at 2°C / min in a box furnace and keep it for 120 minutes, then cool it to 500°C at 5°C / min and finally cool it to room temperature with the furnace to obtain NaNbO3 lead-free ceramic material with a stable antiferroelectric phase.

[0041] Example 6

[0042] Example 6 is basically the same as Example 5, except that the calcination temperature of the mixture in step 1 is 800°C.

[0043] Example 7

[0044] Example 7 is basically the same as Example 5, except that the calcination temperature of the mixture in step 1 is 850°C.

[0045] Example 8

[0046] Example 8 is basically the same as Example 5, except that the calcination temperature of the mixture in step 1 is 900°C.

[0047] Example 9

[0048] This embodiment provides a method for preparing a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase, comprising the following steps:

[0049] Step 1, weighing Na2CO3 and Nb2O5 raw materials according to the same molar ratio to obtain a mixture, taking the mixture, zirconium spherulite and anhydrous ethanol according to the mass ratio of 1:5:1, mixing them and ball milling them for 20 hours, drying them in an oven at 80°C for 12 hours, and then calcining them at 750°C for 3 hours to obtain a complete batch;

[0050] Step 2: Mix all ingredients, zirconium balls and anhydrous ethanol in a mass ratio of 1:4.8:1, ball mill for 24 hours, dry in an oven at 80°C for 12 hours, and pass through a 150-mesh sieve to form a sieved material;

[0051] Step 3: Maintain the pressure of the sieved material at 200 MPa for 3 minutes, then at 190 MPa for 5 minutes, and finally release the pressure at 40 MPa / min to form a green body. The prepared green body is heated to 1330°C at 2°C / min in a box furnace and kept warm for 120 minutes, then cooled to 500°C at 5°C / min and finally cooled to room temperature with the furnace to obtain NaNbO3 lead-free ceramic material with a stable antiferroelectric phase.

[0052] Example 10

[0053] Example 10 is substantially the same as Example 9, except that the calcination temperature of the mixture in step 1 is 800°C.

[0054] Embodiment 11

[0055] Example 11 is basically the same as Example 9, except that the calcination temperature of the mixture in step 1 is 850°C.

[0056] Example 12

[0057] Example 12 is basically the same as Example 9, except that the calcination temperature of the mixture in step 1 is 900°C.

[0058] Embodiment 13

[0059] This embodiment provides a method for preparing a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase, comprising the following steps:

[0060] Step 1, weighing Na2CO3 and Nb2O5 raw materials according to the same molar ratio to obtain a mixture, taking the mixture, zirconium spherulite and anhydrous ethanol according to the mass ratio of 1:5:1, mixing them and ball milling them for 20 hours, drying them in an oven at 80°C for 12 hours, and then calcining them at 750°C for 3 hours to obtain a complete batch;

[0061] Step 2: Mix all ingredients, zirconium balls and anhydrous ethanol in a mass ratio of 1:4.8:1, ball mill for 24 hours, dry in an oven at 80°C for 12 hours, and pass through a 150-mesh sieve to form a sieved material;

[0062] Step 3: Maintain the pressure of the sieved material at 200 MPa for 3 minutes, then at 190 MPa for 5 minutes, and finally release the pressure at 40 MPa / min to form a green body. Heat the prepared green body to 1350°C at 2°C / min in a box furnace and keep it for 120 minutes, then cool it to 500°C at 5°C / min and finally cool it to room temperature with the furnace to obtain NaNbO3 lead-free ceramic material with a stable antiferroelectric phase.

[0063] Embodiment 14

[0064] Example 14 is basically the same as Example 13, except that the calcination temperature of the mixture in step 1 is 800°C.

[0065] Embodiment 15

[0066] Example 15 is basically the same as Example 13, except that the calcination temperature of the mixture in step 1 is 850°C.

[0067] Example 16

[0068] Example 16 is basically the same as Example 13, except that the calcination temperature of the mixture in step 1 is 900°C.

[0069] The prepared ceramic samples were polished and cleaned, and then Ag electrodes were coated on both sides of the samples, and the silver was sintered at 700°C for 20 min before testing.

[0070] Figure 1 XRD patterns of NaNbO3 lead-free ceramics prepared in Examples 5 to 8; Figure 2 is the Raman shift diagram of NaNbO3 prepared in Examples 5 to 8; Figure 1 It can be seen that the {1 3 / 4 1} superlattice reflection peak changes at different pre-sintering temperatures; Figure 2 It can be seen that at different pre-firing temperatures, the Raman peak of the material undergoes significant changes, showing peak shift and merging, which proves that the present invention provides a lead-free sodium niobate ceramic with a stable antiferroelectric phase.

[0071] Figure 3 The relationship between the SEM images of the NaNbO3 antiferroelectric ceramics prepared in Examples 1 to 16 and the sintering temperature and calcining temperature; Figure 4 The relationship between the temperature dependence of the dielectric constant and tangent loss of the NaNbO3 antiferroelectric ceramics prepared in Examples 1 to 16 and the sintering temperature and calcining temperature; Figure 3 It can be seen that the microstructure of NaNbO3 antiferroelectric ceramics has changed significantly. Figure 3 and Figure 4 It can be seen that the material exhibits grain refinement and the Curie peak shifts, which proves that the present invention provides a lead-free sodium niobate ceramic with a stable antiferroelectric phase.

[0072] Embodiment 17

[0073] This embodiment provides a method for preparing a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase, comprising the following steps:

[0074] Step 1, weighing Na2CO3 and Nb2O5 raw materials according to the same molar ratio to obtain a mixture, taking the mixture, zirconium spherulite and anhydrous ethanol according to the mass ratio of 1:2:0.8, mixing them and ball milling them for 12 hours, drying them in an oven at 80°C for 10 hours, and then calcining them at 900°C for 4 hours to obtain a complete batch;

[0075] Step 2: Mix all ingredients, zirconium balls and anhydrous ethanol in a mass ratio of 1:5:0.8, ball mill for 28 hours, dry in an oven at 80°C for 11 hours, and pass through a 100-mesh sieve to form a sieved material;

[0076] Step 3: Maintain the pressure of the sieved material at 210 MPa for 3 minutes, then at 190 MPa for 5 minutes, and finally release the pressure at 40 MPa / min to form a green body. Heat the prepared green body to 1250°C at 2°C / min in a box furnace and keep it for 120 minutes, then cool it to 500°C at 5°C / min and finally cool it to room temperature with the furnace to obtain NaNbO3 lead-free ceramic material with a stable antiferroelectric phase.

[0077] Embodiment 18

[0078] This embodiment provides a method for preparing a NaNbO3 lead-free ceramic material with a stable antiferroelectric phase, comprising the following steps:

[0079] Step 1, weighing Na2CO3 and Nb2O5 raw materials according to the same molar ratio to obtain a mixture, taking the mixture, zirconium spherulite and anhydrous ethanol according to the mass ratio of 1:3:1.5, mixing them and ball milling them for 24 hours, drying them in an oven at 80°C for 11 hours, and then calcining them at 900°C for 3.5 hours to obtain a complete batch;

[0080] Step 2: Mix all ingredients, zirconium balls and anhydrous ethanol in a mass ratio of 1:5.2:1.2, ball mill for 36 hours, dry in an oven at 80°C for 10 hours, and pass through a 200-mesh sieve to form a sieved material;

[0081] Step 3: Maintain the pressure of the sieved material at 220 MPa for 3 minutes, then at 190 MPa for 5 minutes, and finally release the pressure at 40 MPa / min to form a green body. Heat the prepared green body to 1270°C at 2°C / min in a box furnace and keep it for 120 minutes, then cool it to 500°C at 5°C / min and finally cool it to room temperature with the furnace to obtain NaNbO3 lead-free ceramic material with a stable antiferroelectric phase.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the present claims.

Claims

1. A method for preparing a NaNbO3 lead-free ceramic material having a stable antiferroelectric phase, characterized in that: The following steps are involved: Step 1, weighing Na2CO3 and Nb2O5 raw materials according to the same molar ratio to obtain a mixture, ball milling and drying the mixture, and calcining it at 750-900°C for 3-4h to obtain a complete batch; Step 2: ball-mill, dry and sieve all the ingredients again to form sieved material; Step 3: Press the screened material into a green body, and heat the prepared green body to 1250-1350°C in a box furnace at 2°C / min and keep it for 120 minutes, then cool it to 500°C at 5°C / min and finally cool it to room temperature with the furnace to obtain NaNbO3 lead-free ceramic material with a stable antiferroelectric phase.

2. The method for preparing the NaNbO3 lead-free ceramic material having a stable antiferroelectric phase according to claim 1, characterized in that: The ball milling described in step 1 is to mix the mixture, zirconium balls and anhydrous ethanol in a mass ratio of 1: (2-5): (0.8-1.5) and then ball mill for 12-24 hours.

3. The method for preparing the NaNbO3 lead-free ceramic material having a stable antiferroelectric phase according to claim 1, characterized in that: The ball milling described in step 2 is to mix all ingredients, zirconium balls and anhydrous ethanol in a mass ratio of 1: (4.8-5.2): (0.8-1.2) and then ball mill for 24-36 hours.

4. The method for preparing the NaNbO3 lead-free ceramic material having a stable antiferroelectric phase according to claim 1, characterized in that: The drying described in step 1 and step 2 is drying in an oven at 80° C. for 10 to 12 hours.

5. The method for preparing the NaNbO3 lead-free ceramic material having a stable antiferroelectric phase according to claim 1, characterized in that: The mesh number of the sieve described in step 2 is 100 to 200 meshes.

6. The method for preparing the NaNbO3 lead-free ceramic material having a stable antiferroelectric phase according to claim 1, characterized in that: The pressing process described in step 3 is to first maintain the pressure at 200-220 MPa for 3 minutes, then maintain the pressure at 190 MPa for 5 minutes, and finally release the pressure at 40 MPa / min.

7. A NaNbO3 lead-free ceramic material having a stable antiferroelectric phase prepared by the method according to any one of claims 1 to 6.

8. Use of the NaNbO3 lead-free ceramic material having a stable antiferroelectric phase as claimed in claim 7 as an antiferroelectric ceramic.

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