Lead-free antiferroelectric ceramic with low transition field and temperature stability and preparation method thereof

Abstract

The present invention discloses a lead-free antiferroelectric ceramic with low transition field and temperature stability and a preparation method thereof, wherein the stoichiometric formula is: Na 1‑x Bi 2x / 3 Nb 1‑y Zr y O3, 0<x≤0.08, 0<y≤0.08; its preparation method includes: weighing Na2CO3, Nb2O5, ZrO2 and Bi2O3 according to the stoichiometric formula to form a mixture, ball-milling and calcining the mixture to form a complete batch; ball-milling the complete batch again, drying and sieving to form a sieved material; pressing the sieved material into a cylindrical green body, placing the cylindrical green body on a zirconia plate, placing the zirconia plate in an alumina closed sagger and sintering the prepared green body to obtain a lead-free antiferroelectric ceramic with a low transition field and temperature stability. The preparation process is simple, the operation is convenient, the material cost is low, and it is environmentally friendly. It is an important candidate material for high-performance lead-free antiferroelectric ceramic materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, relates to lead-free antiferroelectric ceramic materials, and particularly relates to a lead-free antiferroelectric ceramic with temperature stability and low transition field and a preparation method thereof. Background Art

[0002] Antiferroelectric materials have special structures and properties. Their polarization directions can be instantaneously reversed under the action of an external electric field, so they are widely used in various fields. In scientific research, the physical properties of antiferroelectric materials have always been one of the important fields of materials science research. The special structures and properties of antiferroelectric materials make them have many unique phenomena and behaviors in aspects such as electronic structure, crystal defects, and physical properties. For example, phenomena such as the magnitude of the transition field and temperature stability of antiferroelectric materials have attracted wide attention. Therefore, antiferroelectric materials have been widely studied and applied in disciplines such as physics and materials science.

[0003] Sodium niobate is considered a well-documented antiferroelectric. However, the energy difference between the antiferroelectric phase P and the ferroelectric Q phase of sodium niobate is too close, making it difficult to achieve the characteristics of antiferroelectricity. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a lead-free antiferroelectric ceramic with temperature stability and low transition field and a preparation method thereof, which has a simple preparation process, convenient operation, low material cost, and environmental friendliness.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions to achieve:

[0006] A lead-free antiferroelectric ceramic with temperature stability and low transition field, the chemical formula is: Na 1-x Bi 2x / 3Nb 1-y Zr y O3, 0 < x ≤ 0.08, 0 < y ≤ 0.08.

[0007] The present invention also protects a preparation method of the lead-free antiferroelectric ceramic with temperature stability and low transition field as described above, including the following steps:

[0008] Step 1: Weigh Na2CO3, Nb2O5, ZrO2 and Bi2O3 according to the chemical formula Na 1-x Bi 2x / 3 Nb 1-y Zr y O3, 0 < x ≤ 0.08, 0 < y ≤ 0.08 to form a mixture, and ball-mill and calcine the mixture to form a complete batch of materials;

[0009] Step 2: ball-milling, drying, and sieving all the ingredients again to form sieved materials;

[0010] Step 3: Press the screened material into a cylindrical green body, place the cylindrical green body on a zirconia flat plate, place the zirconia flat plate in an alumina sealed sagger, and sinter the prepared green body to obtain ceramics.

[0011] Preferably, the ball milling in step 1 and step 2 is performed by mixing the mixture, zirconium balls and anhydrous ethanol in a mass ratio of 1:3:1.5 and then ball milling for 24 hours.

[0012] Preferably, the calcination in step 1 is carried out at 900° C. for 4 hours.

[0013] Preferably, the drying in step 2 is performed in an oven at 80° C. for 12 hours.

[0014] Preferably, the mesh size of the sieve used in step 2 is 150 meshes.

[0015] Preferably, the pressing method described in step three is to form a green body by cold isostatic pressing at a pressure of 220 to 240 MPa.

[0016] Preferably, the sintering mechanism described in step three is as follows: in a box furnace, first heating to 500°C at 5°C / min, keeping warm for 3 minutes, then heating to 1000°C at 5°C / min and keeping warm for 30 minutes, then heating to 1310°C at 2°C / min and keeping warm for 120 minutes, then cooling to 1000°C at 2°C / min, then cooling to 500°C at 5°C / min, and finally cooling to room temperature with the furnace.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] Na of the present invention 1-x Bi 2x / 3 Nb 1-y Zr y O3 lead-free antiferroelectric ceramic materials are synthesized by A-site vacancy chemistry to convert Bi 2 / 3 By adding ZrO3 to NaNbO3, a lead-free antiferroelectric ceramic material with temperature stability and a low transition field is prepared. This material exhibits the advantage of maintaining a stable current with temperature changes in the range of 20-160°C. As a steady-state resistor material, it can maintain a stable resistance value in high-temperature environments and can be used in precision circuits in the fields of electronics and electrical engineering.

[0019] Furthermore, its low transition field means lower operating voltage, which reduces energy consumption and improves device reliability, helping to simplify device design and operation;

[0020] The invention has simple preparation process, low material cost, and is green and environmentally friendly, and becomes an important candidate material for lead-free antiferroelectric ceramic materials with temperature stability and low transition field. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Na prepared in Example 1 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 Underdamped discharge waveforms of O3 ceramics under different electric fields;

[0022] Figure 2 Na prepared in Example 1 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 O3 ceramic I max and P D Variation of the spectrum with applied electric field;

[0023] Figure 3 Na prepared in Example 1 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 O3 ceramics at 100kV / cm -1 Overdamped discharge waveforms at different temperatures;

[0024] Figure 4 Na prepared in Example 1 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 O3 ceramic I max and W d Temperature variation graph. DETAILED DESCRIPTION

[0025] The specific contents of the present invention are further explained in detail below with reference to the embodiments.

[0026] Example 1

[0027] This embodiment provides a lead-free antiferroelectric ceramic with low transition field and temperature stability, the stoichiometric formula of which is Na 1-x Bi 2x / 3 Nb 1-y Zr y O3, wherein x=y=0.08, and its preparation method comprises the following steps:

[0028] Step 1: According to the chemical formula Na 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08O3, take Na2CO3, Nb2O5, ZrO2 and Bi2O3 to form a mixture, then take the mixture, zirconium ball stone and anhydrous ethanol, according to the mass ratio of 1:3:1.5, mix them, ball mill for 24 hours, and then calcine at 900℃ for 4 hours to obtain the full ingredients;

[0029] Step 2: All ingredients were mixed with zirconium oxide balls and anhydrous ethanol in a mass ratio of 1:3:1.5, and then ball-milled for 24 hours, and dried in an oven at 80°C for 12 hours to obtain a dried material, which was then ground through a 150-mesh sieve to form a sieved material;

[0030] Step 3: Press the sieved material obtained in step 2 into a cylindrical green body by cold isostatic pressing at a pressure of 200 MPa, place the cylindrical green body on a zirconia plate, place the zirconia plate in an alumina closed sagger, and then place the alumina sagger in a box furnace, first heat it to 500°C at 5°C / min and keep it for 3 minutes, then heat it to 1000°C at 5°C / min and keep it for 30 minutes, then heat it to 1310°C at 2°C / min and keep it for 120 minutes, then cool it to 1000°C at 2°C / min, then cool it to 500°C at 5°C / min, and finally cool it to room temperature with the furnace to obtain a sintered ceramic sample.

[0031] The prepared ceramic samples were polished and cleaned, and then Ag electrodes were coated on both sides of the samples. The silver was calcined at 600°C for 25 minutes and then tested.

[0032] The sample of Example 1 was subjected to underdamped discharge test, and the results were as follows: Figures 1 to 2 As shown, Figure 1 Na prepared in Example 1 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 Underdamped discharge waveforms of O3 ceramics under different electric fields; Figure 1 It can be seen that at room temperature, Na 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 In the underdamped discharge current state of O3 ceramics under different electric field values, the current peak gradually increases with the increase of electric field intensity;

[0033] Figure 2 Na prepared in Example 1 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 O3 ceramic I max and P D The spectrum of the change with the applied electric field shows the effect of the electric field change on the peak current (I max ) and power density (P D=EI max / 2S; S is the electrode area), the current value increases from 17A to 27A, the current peak (I max ) from 60kV / cm -1 to 70kV / cm -1 , through Bi 2 / 3 After ZrO3 is added, the sample exhibits a low transition field phenomenon, proving that the present invention provides an antiferroelectric ceramic with a low transition field.

[0034] The sample of Example 1 was subjected to a damped discharge test, and the results were as follows: Figures 3 and 4 As shown, Figure 3 Na prepared in Example 1 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 O3 ceramics at 100kV / cm -1 Overdamped discharge waveforms at different temperatures; Figure 3 Demonstrated that under a fixed electric field (100kV / cm -1 ) under the condition of temperature, the storage charge and release energy performance change with temperature. As the temperature increases, the stored charge is released at a faster rate (≤0.4μs). At the same time, it can be seen that the thermal stability of the ceramic reaches a stable state in the range of 20~160℃, I max and P D The change does not exceed ±2%;

[0035] Figure 4 Na prepared in Example 1 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 O3 ceramic I max and W d Temperature variation diagram, from Figure 4 It can be seen that Na 0.92 Bi 0.16 / 3 Nb 0.92 Zr 0.08 O3 ceramics exhibit excellent temperature stability characteristics.

[0036] Example 2

[0037] In step 1 of this embodiment, according to Na 1-x Bi 2x / 3 Nb 1-y Zr y O3, wherein the stoichiometric ratio of x=y=0.01, Na2CO3, Nb2O5, ZrO2 and Bi2O3 are weighed respectively, and the other steps are the same as those in Example 1 to obtain a lead-free antiferroelectric ceramic with a low transition field and temperature stability.

[0038] Example 3

[0039] In step 1 of this embodiment, according to Na 1-x Bi 2x / 3 Nb 1-y Zr y O3, wherein the stoichiometric ratio of x=y=0.02, Na2CO3, Nb2O5, ZrO2 and Bi2O3 are weighed respectively, and the other steps are the same as those in Example 1 to obtain a lead-free antiferroelectric ceramic with a low transition field and temperature stability.

[0040] Example 4

[0041] In step 1 of this embodiment, according to Na 1-x Bi 2x / 3 Nb 1-y Zr y O3, wherein the stoichiometric ratio of x=y=0.04, Na2CO3, Nb2O5, ZrO2 and Bi2O3 are weighed respectively, and the other steps are the same as those in Example 1 to obtain a lead-free antiferroelectric ceramic with a low transition field and temperature stability.

[0042] Example 5

[0043] In step 1 of this embodiment, according to Na 1-x Bi 2x / 3 Nb 1-y Zr y O3, wherein the stoichiometric ratio of x=y=0.06, Na2CO3, Nb2O5, ZrO2 and Bi2O3 are weighed respectively, and the other steps are the same as those in Example 1 to obtain a lead-free antiferroelectric ceramic with a low transition field and temperature stability.

[0044] 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 the present invention. 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 methods of the present invention may still be modified or replaced by equivalents. 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 protection of the claims of the present invention.

Claims

1. A lead-free antiferroelectric ceramic with a low transition field and temperature stability, characterized in that: The stoichiometric formula is: Na 1-x Bi 2x / 3 Nb 1-y Zr y O3, x=y=0.01, 0.02, 0.04, 0.06, 0.

08.

2. A method for preparing a temperature-stable, low-transition-field lead-free antiferroelectric ceramic according to claim 1, characterized in that: The following steps are involved: Step 1: According to the stoichiometric formula Na 1-x Bi 2x / 3 Nb 1-y Zr y O3, x=y=0.01, 0.02, 0.04, 0.06, 0.08, weigh Na2CO3, Nb2O5, ZrO2 and Bi2O3 to form a mixture, and ball mill and calcine the mixture to form a complete batch; Step 2: ball-milling, drying, and sieving all the ingredients again to form sieved materials; Step 3: Press the screened material into a cylindrical green body, place the cylindrical green body on a zirconia flat plate, place the zirconia flat plate in an alumina sealed sagger, and sinter the prepared green body to obtain ceramics.

3. The method for preparing a temperature-stable, low-transition-field lead-free antiferroelectric ceramic according to claim 2, wherein: The ball milling in step 1 and step 2 is performed by mixing the mixture, zirconium balls and anhydrous ethanol in a mass ratio of 1:3:1.5 and then ball milling for 24 hours.

4. The method for preparing a temperature-stable, low-transition-field lead-free antiferroelectric ceramic according to claim 2, wherein: The calcination in step 1 is performed at 900° C. for 4 h.

5. The method for preparing a lead-free antiferroelectric ceramic with a low transition field and temperature stability according to claim 2, wherein: The drying step is carried out in an oven at 80°C for 12 hours.

6. The method for preparing a temperature-stable, low-transition-field lead-free antiferroelectric ceramic according to claim 2, wherein: The mesh number of the sieve described in step 2 is 150 meshes.

7. The method for preparing a temperature-stable, low-transition-field lead-free antiferroelectric ceramic according to claim 2, wherein: The pressing method described in step 3 is to form a green body by cold isostatic pressing at a pressure of 220 to 240 MPa.

8. The method for preparing a temperature-stable, low-transition-field lead-free antiferroelectric ceramic according to claim 2, wherein: The sintering mechanism described in step 3 is as follows: in a box furnace, first heat the temperature to 500°C at 5°C / min and keep it for 3 minutes, then heat the temperature to 1000°C at 5°C / min and keep it for 30 minutes, then heat the temperature to 1310°C at 2°C / min and keep it for 120 minutes, then cool it to 1000°C at 2°C / min, then cool it to 500°C at 5°C / min, and finally cool it to room temperature with the furnace.

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