Lead-free piezoelectric ceramic material and preparation method thereof

Abstract

The invention discloses a lead-free piezoelectric ceramic material and a preparation method thereof, the chemical general formula of the lead-free piezoelectric ceramic material is (0.96-x) K < 0.48 > Na < 0.52 > Nb < 0.98 > Sb < 0.02-0.04 > Bi < 0.5 > Na < 0.5 > ZrO < 3-x > Bi < 0.5 > Ag < 0.5 > ZrO < 3 >, x is greater than or equal to 0.005 and less than or equal to 0.03, and y is greater than or equal to 0.05 and less than or equal to 0.03. The content of the Ag element in the ceramic material is 0.15-0.87 wt%; according to the ceramic material, a compound Bi0. 5Ag0. 5ZrO3 is introduced on the basis of KNNS-BNZ-based ceramic to regulate and control a piezoelectric ceramic structure, so that phase transformation temperatures TR-O and TO-T are transferred to room temperature, and a three-phase coexistence phase boundary of a nanoscale trigonal phase (R)-orthorhombic phase (O)-tetragonal phase (T) is constructed in a room temperature region.

Description

Technical Field

[0001] The present invention relates to the technical field of lead-free piezoelectric ceramics, and in particular to a KNNS-BNZ (sodium potassium niobate-sodium bismuth zirconate) based lead-free piezoelectric ceramic material and a preparation method thereof. Background Art

[0002] Piezoelectric ceramics are information functional ceramic materials that can convert mechanical energy and electrical energy into each other. They have piezoelectric effect characteristics, dielectric properties and elastic properties. They are key materials for core devices in the fields of information communication, biomedicine, military industry and national defense. The piezoelectric effect includes positive piezoelectric effect and inverse piezoelectric effect. The positive piezoelectric effect means that when the piezoelectric material is acted upon by an external force, it can convert mechanical energy into electrical energy. Conversely, the inverse piezoelectric effect means that when an alternating voltage is applied to the piezoelectric material, electrical energy is converted into mechanical energy, causing the piezoelectric material to deform. The piezoelectric coefficient is the conversion coefficient of the piezoelectric body to convert mechanical energy into electrical energy or vice versa, reflecting the coupling relationship between the elastic (mechanical) properties and dielectric properties of the piezoelectric material.

[0003] In order to meet the new application requirements, piezoelectric devices are developing in the direction of multilayer, chip-type and miniaturization. In recent years, some new piezoelectric devices such as multilayer piezoelectric transformers, multilayer piezoelectric drivers, and chip-type piezoelectric frequency devices have been continuously developed and widely used in sensors, actuators, underwater acoustic transducers, energy harvesters and other fields. At the same time, in terms of new materials, the development of lead-free piezoelectric ceramics has made great breakthroughs, which may enable lead-free piezoelectric ceramics to replace lead zirconate titanate (PZT)-based piezoelectric ceramics in many fields and promote the upgrading of green electronic products.

[0004] Potassium sodium niobate (KNN) lead-free piezoelectric ceramics are considered to be one of the most promising lead-free piezoelectric ceramics to replace lead-based piezoelectric ceramics in sensor applications due to their high Curie temperature, adjustable phase boundary structure, and excellent piezoelectric properties. However, although the Curie temperature Tc of pure KNN piezoelectric ceramics is as high as 420℃, the piezoelectric coefficient D 33 It is only 80pC / N, and it is difficult to sinter densely, which cannot meet the use requirements of conventional piezoelectric devices. Therefore, how to improve the comprehensive performance of KNN-based piezoelectric ceramics has become a research hotspot in the industry. Summary of the invention

[0005] The main purpose of the present invention is to propose a lead-free piezoelectric ceramic material and a preparation method thereof, and to improve the piezoelectric coefficient of KNN-based lead-free piezoelectric ceramics by adjusting the components and controlling the ceramic structure, so as to solve the problem of low piezoelectric coefficient and poor comprehensive performance of existing pure KNN system piezoelectric ceramics.

[0006] To achieve the above object, one aspect of the present invention proposes the following technical solutions:

[0007] A lead-free piezoelectric ceramic material, the chemical formula of the lead-free piezoelectric ceramic material is:

[0008] (0.96-x)K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-xBi 0.5 Ag 0.5 ZrO3, wherein 0.005≤x≤0.03.

[0009] Furthermore, the content of Ag element in the lead-free piezoelectric ceramic material is 0.15-0.87 wt %.

[0010] Furthermore, the lead-free piezoelectric ceramic material has a nanoscale rhombohedral phase (R)-orthorhombic phase (O)-tetragonal phase (T) three-phase coexistence phase boundary in the room temperature region.

[0011] Furthermore, the lead-free piezoelectric ceramic material is a lead-free piezoelectric ceramic material that is based on KNNS-BNZ ceramics and introduces the compound Bi 0.5 Ag 0.5 ZrO3, to adjust the piezoelectric ceramic structure, so that the phase transition temperature T R-O and T O-T The mixture is transferred to room temperature to construct the nanoscale rhombohedral (R)-orthorhombic (O)-tetragonal (T) three-phase coexistence phase boundary in the room temperature region.

[0012] Another aspect of the present invention further provides a method for preparing a lead-free piezoelectric ceramic material, which is used to prepare the aforementioned lead-free piezoelectric ceramic material. The preparation method comprises:

[0013] 1) Using K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 as raw materials, according to the chemical formula (0.96-x)K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-xBi 0.5 Ag 0.5 ZrO3 ingredients;

[0014] 2) ball milling the prepared raw materials;

[0015] 3) Pre-burning the ball-milled material;

[0016] 4) performing secondary ball milling on the pre-burned material;

[0017] 5) Granulating the material after the secondary ball milling and pressing it into green compacts;

[0018] 6) Debinding and sintering the green body to obtain the lead-free piezoelectric ceramic material.

[0019] Further, in step 1), the mass ratio of K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 is

[0020] 1616~1553:1390~1337:6288~6043:141~136:267~410:283~434:15~87.

[0021] Furthermore, step 1) also includes: heat treating the raw materials K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 at different temperatures respectively, and then mixing the ingredients after the heat treatment.

[0022] Furthermore, zirconium balls and anhydrous ethanol are added during the ball milling process in step 2) and step 4), and grinding and sieving are performed after ball milling and drying.

[0023] Furthermore, step 5) specifically includes: adding the material obtained in step 4) into a PVB ethanol solution with a concentration of 8-15wt%, grinding and granulating, and then pressing into a green body at a pressure of 100-150MPa.

[0024] Furthermore, step 6) specifically includes: placing the green body obtained in step 5) into a furnace and heating it to 500-600°C and keeping it warm for 1-3 hours to perform debinding treatment; then continuing to heat it to 1100-1160°C and keeping it warm for 2-6 hours to perform densification sintering; then cooling it to 850-600°C at a cooling rate of 2-5°C / min and then cooling it to room temperature in the furnace to obtain the lead-free piezoelectric ceramic material.

[0025] The beneficial effects of the technical solution of the present invention are mainly reflected in: KNN has a rich phase structure. As the temperature changes, KNN ceramics will undergo a rhombohedral phase (R)-orthorhombic phase (O) transition at -123°C, an orthorhombic phase-tetragonal phase (T) transition at 210°C, and a tetragonal phase-cubic phase (C) transition at 410°C. The R phase has 8 spontaneous polarization directions. <111> , O phase has 12 spontaneous polarization directions <011> , and the T phase has 6 spontaneous polarization directions <001> The contribution of the piezoelectric performance of ceramics comes from both intrinsic and extrinsic parts. To improve the piezoelectric performance, the intrinsic contribution, that is, the contribution of phase change, must be increased. Therefore, the present invention constructs a quasi-morphous phase boundary (MPB) or polymorphic phase boundary (PPB) structure similar to that in lead-based piezoelectric ceramics in KNN, that is, at 0.96 (K 0.48 Na0.52 )(Nb 0.98 Sb 0.02 )-0.04(Bi 0.5 Na 0.5 )ZrO3 matrix is ​​further regulated by introducing compound Bi 0.5 Ag 0.5 ZrO3, the phase transition temperature T R-O and T O-T Transferred to room temperature, thereby constructing a ROT phase boundary with more spontaneous polarization directions in the room temperature region, increasing the intrinsic contribution of KNN-based ceramics, thereby increasing the piezoelectric coefficient of KNN-based lead-free piezoelectric ceramics, and ultimately improving the comprehensive performance of KNN-based piezoelectric ceramics. At the same time, the sintering temperature of KNN-based lead-free piezoelectric ceramics can be reduced to a certain extent, and the sintering density can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of a method for preparing a lead-free piezoelectric ceramic material according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods and examples. It should be noted that the purpose of providing the examples is only to illustrate, and not to limit the scope of protection of the present invention.

[0028] The embodiment of the present invention provides an improved lead-free piezoelectric ceramic material, which is a 0.96 (K 0.48 Na 0.52 )(Nb 0.98 Sb 0.02 )-0.04(Bi 0.5 Na 0.5 )ZrO3 (i.e. KNNS-BNZ) binary system ceramic materials, based on the compound Bi 0.5 Ag 0.5 The KNNS-BNZ-BAZ ternary system piezoelectric ceramic material is prepared by introducing Ag element in the form of ZrO3. 0.5 Ag 0.5 Ag is introduced in the form of ZrO3 to regulate the structure of KNN piezoelectric ceramics, so as to construct a quasi-morphous phase boundary (MPB) or polymorphic phase boundary (PPB) structure in KNN similar to that in lead-based piezoelectric ceramics PZT, so that the phase transition temperature T R-O and T O-T Transfer to room temperature, thereby constructing a nanoscale rhombohedral phase (R)-orthorhombic phase (O)-tetragonal phase (T) three-phase coexistence phase boundary in the room temperature region, improving the intrinsic contribution of the KNN-based ceramic and improving the piezoelectric properties of the piezoelectric ceramic. The general chemical formula of the ceramic material of the embodiment of the present invention is

[0029] (0.96-x)K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-xBi 0.5 Ag 0.5 ZrO3, wherein 0.005≤x≤0.03.

[0030] In the ceramic material of the embodiment of the present invention, the content of Ag element is 0.15-0.87 wt %.

[0031] The present invention also provides a method for preparing a lead-free piezoelectric ceramic material having the above chemical formula, Figure 1 , the preparation method comprises:

[0032] 1) Using analytically pure K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 as raw materials, the raw materials were first heat treated at different temperatures, and then the raw materials were heated according to the chemical formula (0.96-x)K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-xBi 0.5 Ag 0.5 The mass ratios of ZrO3 ingredients, K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 are: 1616~1553:1390~1337:6288~6043:141~136:267~410:283~434:15~87.

[0033] 2) Add zirconium balls and anhydrous ethanol to the prepared raw materials for rolling ball milling, and the ball milled slurry is dried and sieved for later use;

[0034] 3) The powder obtained in step 2) is pressed into blocks and then placed in a furnace, heated to 800-900° C. and kept warm for 3-6 hours, then cooled to room temperature with the furnace to complete pre-burning, and the pre-burned material is ground and sieved for later use;

[0035] 4) performing secondary ball milling on the material obtained in step 3), and drying and sieving the ball milled slurry for later use;

[0036] 5) adding 8-15 wt % PVB ethanol solution to the material obtained in step 4), grinding, granulating, and sieving for later use;

[0037] 6) pressing the material obtained in step 5) into a green body at a pressure of 100 to 150 MPa;

[0038] 7) placing the green body obtained in step 6) into a furnace and heating it to 500-600°C for 1-3 hours to perform a debinding treatment; then continuing to heat it to 1100-1160°C and keeping it for 2-6 hours to perform a densification sintering, and then cooling it to 850-600°C at a cooling rate of 2-5°C / min and then cooling it to room temperature in the furnace, thereby preparing the lead-free piezoelectric ceramic material of the embodiment of the present invention, which has the aforementioned general chemical formula.

[0039] The preparation method of the present invention is described in more detail below through several examples.

[0040] Example 1

[0041] Step 1: Use analytical pure K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 as raw materials, according to the chemical formula

[0042] 0.955K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-0.005Bi 0.5 Ag 0.5 ZrO3 ingredients, wherein the mass ratio of K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 is 1616:1390:6288:141:267:283:15;

[0043] Step 2: Pour 50g of the prepared raw materials into a fluorination bottle, add 100g of zirconium balls and 30g of anhydrous ethanol, and mix on a roller mill for 24h;

[0044] Step 3: Pour the slurry obtained in step 2 into a glass culture dish, place it in an oven at 80°C and dry it, grind it through an 80-mesh sieve for later use;

[0045] Step 4: Place the powder obtained in step 3 into a mold with a diameter of 40 mm and press it into a columnar block, place it in a programmable temperature-controlled box furnace, heat it to 850°C at a heating rate of 5°C / min and keep it for 6 hours, then cool it to room temperature with the furnace to complete pre-sintering, and grind the pre-sintered powder through an 80-mesh sieve for later use;

[0046] Step 5: Place the powder obtained in step 4 into a fluorination bottle for secondary ball milling and rolling for 24 hours;

[0047] Step 6: Pour the slurry obtained in step 5 into a glass culture dish, place it in an oven at 80°C and dry it, grind it through an 80-mesh sieve for later use;

[0048] Step 7: Add the powder obtained in step 6 to a 10 wt% PVB ethanol solution, grind and granulate the powder, and then sieve it through an 80-mesh sieve for later use;

[0049] Step 8: Place the powder obtained in step 7 into a mold with a diameter of 10 mm and press it into a green body at a pressure of 127 MPa;

[0050] Step 9: Place the green body obtained in step 8 into a programmable temperature-controlled box furnace, heat it to 600°C at a heating rate of 2°C / min and keep it for 2h for debinding treatment, then heat it to 1100-1160°C at a heating rate of 2°C / min and keep it for 2h for densification sintering, finally cool it to 600°C at a cooling rate of 2°C / min and cool it to room temperature with the furnace, and the chemical formula of 0.955K can be prepared. 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-0.005Bi 0.5 Ag 0.5 Lead-free piezoelectric ceramic material of ZrO3.

[0051] This embodiment also provides a process for electrode processing of the lead-free piezoelectric ceramic material prepared above, which specifically includes:

[0052] The lead-free piezoelectric ceramic sheet obtained in the above step nine was polished smooth with sandpaper, and silver paste was evenly applied on both sides of the ceramic sheet with a brush. After drying in an oven at 80°C, it was placed in a muffle furnace for silver burning, and the temperature was increased to 850°C at a rate of 5°C / min, kept warm for 30min, and then cooled to room temperature with the furnace; the obtained ceramic sheet was then placed in high-temperature silicone oil at 100°C, an electric field of 30kV / cm was applied, and the pressure was maintained for 20min for polarization.

[0053] After polarization, the electrical performance test was carried out and the results are as follows:

[0054] Sintering temperature / ℃ <![CDATA[d 33 (PC / N)]]> <![CDATA[d 31 (PC / N)]]> Kp(%) Q Tc 1160 380 -151 42 39 298

[0055] Example 2

[0056] Using analytical pure K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 as raw materials, according to the chemical formula

[0057] 0.945K 0.48 Na 0.52 Nb 0.98 Sb0.02 -0.04Bi 0.5 Na 0.5 ZrO3-0.015Bi 0.5 Ag 0.5 ZrO3 ingredients; wherein the mass ratio of K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 is 1591:1368:6189:139:325:344:44. The preparation steps are the same as those in Example 1, and the test results are as follows:

[0058] Sintering temperature / ℃ <![CDATA[d 33 (PC / N)]]> d31(PC / N) Kp(%) Q Tc 1150 404 -165 45 41 285

[0059] Example 3

[0060] Using analytical pure K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 as raw materials, according to the chemical formula

[0061] 0.935K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-0.025Bi 0.5 Ag 0.5 ZrO ingredients; wherein the mass ratio of K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 is 1565:1347:6091:137:382:404:73, the preparation steps are the same as in Example 1, and the test results are as follows:

[0062] Sintering temperature / ℃ <![CDATA[d 33 (PC / N)]]> <![CDATA[d 31 (PC / N)]]> Kp(%) Q Tc 1140 435 -176 55 45 276

[0063] Example 4

[0064] Using analytical pure K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 as raw materials, according to the chemical formula

[0065] 0.93K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-0.03Bi 0.5 Ag 0.5ZrO3 ingredients, wherein the mass ratio of K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 is 1553:1337:6043:136:410:434:87, the preparation steps are the same as those in Example 1, and the test results are as follows:

[0066] Sintering temperature / ℃ <![CDATA[d 33 (PC / N)]]> <![CDATA[d 31 (PC / N)]]> Kp(%) Q Tc 1140 402 -162 48 44 273

[0067] Example 5

[0068] Using analytical pure K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 as raw materials, according to the chemical formula

[0069] 0.95K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-0.01Bi 0.5 Ag 0.5 ZrO3 ingredients, wherein the mass ratio of K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 is 1603:1379:6239:140:296:313:29, the preparation steps are the same as in Example 1, and the test results are as follows:

[0070] Sintering temperature / ℃ <![CDATA[d 33 (PC / N)]]> <![CDATA[d 31 (PC / N)]]> Kp(%) Q Tc 1160 395 -160 43 40 290

[0071] Example 6

[0072] Using analytical pure K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 as raw materials, according to the chemical formula

[0073] 0.94K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-0.02Bi 0.5 Ag 0.5 ZrO3 ingredients, wherein the mass ratio of K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 is 1578:1358:6140:138:354:374:58, the preparation steps are the same as in Example 1, and the test results are as follows:

[0074] Sintering temperature / ℃ <![CDATA[d 33 (PC / N)]]> <![CDATA[d 31 (PC / N)]]> Kp(%) Q Tc 1150 410 -167 49 43 281

[0075] Comparative Example 1

[0076] Step 1: Use analytical pure K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3 and ZrO2 as raw materials, according to the chemical formula 0.96K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3 ingredients, wherein the mass ratio of K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3 and ZrO2 is 1618:1398:6354:142:237:250;

[0077] Step 2: Weigh 50 g of the prepared raw materials and pour them into a fluorination bottle, add 100 g of zirconium balls and 30 g of anhydrous ethanol, and mix them on a roller mill for 24 hours;

[0078] Step 3: Pour the slurry obtained in step 2 into a glass culture dish, place it in an oven at 80°C, dry it, grind it, and pass it through an 80-mesh sieve for later use;

[0079] Step 4: Place the powder obtained in step 3 into a mold with a diameter of 40 mm and press it into a columnar block, place it in a programmable temperature-controlled box furnace, heat it to 850°C at a heating rate of 5°C / min and keep it for 6 hours, then cool it to room temperature with the furnace, grind the pre-burned columnar powder through an 80-mesh sieve for later use;

[0080] Step 5: Place the powder obtained in step 4 into a fluorination bottle and perform secondary ball milling for 24 hours;

[0081] Step 6: Pour the slurry obtained in step 5 into a glass culture dish and place it in an oven at 80°C for drying, and grind it through an 80-mesh sieve for later use;

[0082] Step 7: Add an appropriate amount of 10 wt% PVB ethanol solution to the powder obtained in step 6, grind and granulate it, and then pass it through an 80-mesh sieve for later use;

[0083] Step 8: Place the powder obtained in step 7 into a mold with a diameter of 10 mm and press it into a green body at a pressure of 127 MPa;

[0084] Step 9: Place the green body obtained in step 8 into a programmable temperature-controlled box furnace, heat the temperature to 600°C at a heating rate of 2°C / min and keep it for 2 hours for debinding treatment, then heat the temperature to 1100-1160°C at a heating rate of 2°C / min and keep it for 2 hours for densification sintering, and finally cool the temperature to 600°C at a cooling rate of 2°C / min and cool it to room temperature with the furnace;

[0085] Step 10, polish the ceramic sheet obtained in step 9 with sandpaper to make it smooth, apply silver paste evenly on both sides of the ceramic sheet with a brush, dry it in an oven at 80°C, place it in a muffle furnace to burn silver, increase the temperature to 850°C at a rate of 5°C / min, keep it warm for 30 minutes, and then cool it to room temperature with the furnace;

[0086] Step 11: Place the ceramic sheet obtained in step 10 in high-temperature silicone oil at 100°C, apply an electric field of 30 kV / cm, and maintain the voltage for 20 minutes for polarization. After polarization, conduct an electrical performance test. The results are as follows:

[0087] Sintering temperature / ℃ <![CDATA[d 33 (PC / N)]]> <![CDATA[d 31 (PC / N)]]> Kp(%) Q Tc 1170 370 -150 41 38 301

[0088] By comparison, it can be seen that the present invention introduces Ag element into the piezoelectric ceramic material, and the prepared chemical formula is (0.96-x)K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-xBi 0.5 Ag 0.5 The comprehensive piezoelectric performance of ZrO3 lead-free piezoelectric ceramic materials is improved, and the sintering temperature is reduced. Specifically, the piezoelectric coefficient, especially D 33 Increased to 380~435PC / N, in addition, the electromechanical coupling coefficient K P The mechanical quality factor Qm is also improved accordingly, and the comprehensive performance is better. In summary, the preparation method provided by the embodiment of the present invention can prepare a chemical formula of (0.96-x)K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-xBi 0.5 Ag 0.5 ZrO3 high-performance lead-free piezoelectric ceramic material, this ceramic material not only reduces the sintering temperature, but also has a piezoelectric constant D 33 Higher, better comprehensive piezoelectric performance; and environmentally friendly, lower cost, and easier to industrialize.

[0089] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, several equivalent substitutions or obvious variations can be made without departing from the concept of the present invention, and the performance or use is the same, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A lead-free piezoelectric ceramic material, characterized in that: The chemical formula of the lead-free piezoelectric ceramic material is: (0.96-x)K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-xBi 0.5 Ag 0.5 ZrO3, of which 0.005≤x≤0.

03.

2. The lead-free piezoelectric ceramic material according to claim 1, characterized in that: The content of Ag element in the lead-free piezoelectric ceramic material is 0.15-0.87 wt %.

3. The lead-free piezoelectric ceramic material according to claim 1, characterized in that: The lead-free piezoelectric ceramic material has a nanoscale rhombohedral phase (R)-orthorhombic phase (O)-tetragonal phase (T) three-phase coexistence phase boundary in the room temperature region.

4. The lead-free piezoelectric ceramic material according to claim 3, characterized in that: The lead-free piezoelectric ceramic material is a KNNS-BNZ-based ceramic material that introduces the compound Bi 0.5 Ag 0.5 ZrO3, to adjust the piezoelectric ceramic structure, so that the phase transition temperature T R-O and T O-T The mixture is transferred to room temperature to construct the nanoscale rhombohedral (R)-orthorhombic (O)-tetragonal (T) three-phase coexistence phase boundary in the room temperature region.

5. A method for preparing a lead-free piezoelectric ceramic material, used for preparing the lead-free piezoelectric ceramic material according to any one of claims 1 to 4, characterized in that: The preparation method comprises: 1) Using K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 as raw materials, according to the chemical formula (0.96-x)K 0.48 Na 0.52 Nb 0.98 Sb 0.02 -0.04Bi 0.5 Na 0.5 ZrO3-xBi 0.5 Ag 0.5 ZrO3 distribution; 2) ball milling the prepared raw materials; 3) Pre-burning the ball-milled material; 4) performing secondary ball milling on the pre-burned material; 5) Granulating the material after the secondary ball milling and pressing it into green compacts; 6) Debinding and sintering the green body to obtain the lead-free piezoelectric ceramic material.

6. The preparation method according to claim 5, characterized in that: In step 1), the mass ratio of K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 is 1616-1553:1390-1337:6288-6043:141-136:267-410:283-434:15-87.

7. The preparation method according to claim 5, characterized in that: Step 1) also includes: heat treating the raw materials K2CO3, Na2CO3, Nb2O5, Sb2O3, Bi2O3, ZrO2 and AgO2 at different temperatures respectively, and then mixing the ingredients after the heat treatment.

8. The preparation method according to claim 5, characterized in that: In the ball milling process in step 2) and step 4), zirconium balls and anhydrous ethanol are added, and grinding and sieving are performed after ball milling and drying.

9. The preparation method according to claim 5, characterized in that: Step 5) specifically comprises: adding the material obtained in step 4) into a PVB ethanol solution with a concentration of 8-15 wt%, grinding and granulating, and then pressing the material into a green body at a pressure of 100-150 MPa.

10. The preparation method according to claim 5, characterized in that: Step 6) specifically includes: placing the green body obtained in step 5) into a furnace and heating it to 500-600°C and keeping it for 1-3 hours to perform a debinding treatment; then continuing to heat it to 1100-1160°C and keeping it for 2-6 hours to perform a densification sintering; then cooling it to 850-600°C at a cooling rate of 2-5°C / min and then cooling it to room temperature in the furnace to obtain the lead-free piezoelectric ceramic material.

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