Lead-free ceramic, method for producing the same, ceramic powder, piezoelectric ceramic, and atomizing device

Abstract

The application relates to a lead-free ceramic and a preparation method thereof, a ceramic powder, a piezoelectric ceramic and an atomization device. The lead-free ceramic comprises a main component represented by a chemical formula (1-x)(K y Na 1‑y )(Nb a Sb 0.97‑a Ta 0.03 )O3-x(Bi b Na 1‑b ZrO3)‑cMnO2, wherein x, y, a and b respectively represent particle numbers, 0<=x<1, 0<y<1, 0<=a<=0.97, 0<b<1, and c represents the mass percentage of MnO2 in the main component, 0<=c<=1%. The lead-free ceramic contains a potassium sodium niobate phase with a specific proportion of Ta elements, the reasonable proportioning of the lead-free ceramic composition is good in piezoelectric performance, and the lead-free ceramic is good in piezoelectric constant, mechanical quality factor and electromechanical coupling coefficient.

Description

Technical Field

[0001] This invention relates to the field of ceramic technology, and in particular to a lead-free ceramic and its preparation method, ceramic powder, piezoelectric ceramic, and atomizing device. Background Technology

[0002] An ultrasonic nebulizer is a device that uses high-frequency electronic oscillations to drive the deformation or vibration of a perforated plate through the high-frequency resonance of a piezoelectric ceramic sheet, causing the liquid to be sprayed out of the perforations and atomized. Ultrasonic nebulizers are widely used in the medical industry.

[0003] Piezoelectric ceramics are crucial driving components in ultrasonic nebulizers. Traditional piezoelectric ceramics are primarily lead-based. During operation, lead-based piezoelectric ceramics come into direct contact with the medication or other media, and the atomized drug particles are directly inhaled into the lungs. The lead in lead-based piezoelectric ceramics poses a potential health risk and should therefore be avoided in medical nebulizers. Summary of the Invention

[0004] Therefore, it is necessary to provide a lead-free ceramic with better piezoelectric properties, which can replace traditional lead-containing piezoelectric ceramics and be suitable for medical nebulizers, thus avoiding the harm of lead to the human body.

[0005] In addition, a ceramic powder for preparing the lead-free ceramic, a method for preparing the ceramic, a piezoelectric ceramic including the lead-free ceramic, and an atomizing device including the piezoelectric ceramic are also provided.

[0006] One aspect of this application provides a lead-free ceramic comprising a chemical formula (1-x)(K y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b The main component is represented by ZrO3-cMnO2, where x, y, a, and b represent the number of particles, 0 ≤ x < 1, 0 < y < 1, 0 < a ≤ 0.97, 0 < b < 1, and c represents the mass percentage of MnO2 in the main component, 0 ≤ c ≤ 1%.

[0007] The lead-free ceramics provided in this application mainly include those with the chemical formula (1-x)(K y Na 1-y (Nb) a Sb 0.97- a Ta 0.03 O3-x(Bi) b Na 1-bThe main component is represented by ZrO3-cMnO2, where x, y, a, and b represent the number of particles, 0 ≤ x < 1, 0 < y < 1, 0 < a ≤ 0.97, 0 < b < 1, and c represents the mass percentage of MnO2 in the main component, 0 ≤ c ≤ 1%. Lead-free ceramics contain a specific proportion of potassium sodium niobate (KNN) phase with Ta element. Through a reasonable ratio of lead-free ceramic components, the aforementioned lead-free ceramics exhibit good piezoelectric properties, possessing excellent piezoelectric constant, mechanical quality factor, and electromechanical coupling coefficient.

[0008] In some embodiments, the lead-free ceramic satisfies at least one of the following conditions (1) to (5):

[0009] (1) 0 ≤ x ≤ 0.08;

[0010] (2) 0.4 ≤ y ≤ 0.5;

[0011] (3) 0.8 ≤ a ≤ 0.97;

[0012] (4) 0.2 ≤ b ≤ 0.8;

[0013] (5) 0.2% ≤ c ≤ 0.8%.

[0014] In some implementations, 0.02≤x≤0.06, 0.43≤y≤0.48, 0.9≤a≤0.97, 0.5≤b≤0.65, and 0.4%≤c≤0.8%.

[0015] In some embodiments, the main component includes 0.94 (K) 0.48 Na 0.52 (Nb) 0.97 Ta 0.03 O3-0.06(Bi) 0.6 Na 0.4 ZrO3)-0.6% MnO2, 0.94% K 0.43 Na 0.57 (Nb) 0.97 Ta 0.03 O3-0.06(Bi) 0.6 Na 0.4 ZrO3)-0.5% MnO2 and 0.94% K 0.45 Na 0.55 (Nb) 0.97 Ta 0.03 O3-0.06(Bi) 0.6 Na 0.4 One of ZrO3 and 0.5% MnO2.

[0016] In some embodiments, the main component in the lead-free ceramic is ≥94% by mass;

[0017] Optionally, the main component in the lead-free ceramic is 94% to 100% by mass.

[0018] In some embodiments, the lead-free ceramic further includes a dopant element M, wherein M includes at least one of Cu, Sr, Ba, Ca, Zn, La, Li and Mg.

[0019] In some embodiments, the mass percentage of each of the doping elements M in the lead-free ceramic is ≤1%.

[0020] In some embodiments, the sum of the mass percentages of each of the dopant elements M in the lead-free ceramic is ≤5%.

[0021] Another aspect of this application provides a method for preparing lead-free ceramics, comprising the following steps:

[0022] Based on the above-described composition of lead-free ceramics, raw materials were weighed, and the lead-free ceramics were prepared using a solid-state synthesis method.

[0023] In some embodiments, the step of weighing raw materials according to the composition of lead-free ceramics and preparing lead-free ceramics using a solid-state synthesis method includes:

[0024] Raw materials are weighed according to the composition of the lead-free ceramic, and the raw materials are ground and pre-fired to prepare ceramic powder; and

[0025] The ceramic powder is granulated, shaped, debinded, and sintered to prepare the lead-free ceramic.

[0026] In some embodiments, the raw materials for the main components of the lead-free ceramic include potassium source, sodium source, niobium source, antimony source, tantalum source, bismuth source, zirconium source and manganese source;

[0027] Optionally, the potassium source includes at least one of K2O and K2CO3; the sodium source includes at least one of Na2O and Na2CO3; the niobium source includes Nb2O5; the antimony source includes Sb2O3; the tantalum source includes Ta2O5; the bismuth source includes Bi2O3; the zirconium source includes ZrO2; and the manganese source includes MnO2.

[0028] In some embodiments, when the lead-free ceramic further includes a dopant element M, the dopant element M is at least one of oxides, nitrates and carbonates as raw materials.

[0029] Another aspect of this application provides a ceramic powder comprising a powder of the chemical formula (1-x)(K y Na 1-y (Nb) a Sb0.97-a Ta 0.03 O3-x(Bi) b Na 1-b The main component is represented by ZrO3-cMnO2, where x, y, a, and b represent the number of particles, 0 ≤ x < 1, 0 < y < 1, 0 < a ≤ 0.97, 0 < b < 1, and c represents the mass percentage of MnO2 in the main component, 0 ≤ c ≤ 1%.

[0030] In another aspect, this application also provides a piezoelectric ceramic, which includes a ceramic body and an electrode located on the ceramic body, wherein the ceramic body is the lead-free ceramic described above or obtained using the ceramic powder described above.

[0031] Another aspect of this application provides an atomizing device comprising the aforementioned piezoelectric ceramic. Attached Figure Description

[0032] Figure 1 The X-ray diffraction (XRD) patterns of the lead-free ceramics prepared in Examples 5, 7, and 8 of this application are shown.

[0033] Figure 2 The images shown are scanning electron microscope (SEM) images of the lead-free ceramics prepared in Examples 5, 7, and 8 of this application; where a is the lead-free ceramic of Example 5, b is the lead-free ceramic of Example 7, and c is the lead-free ceramic of Example 8. Detailed Implementation

[0034] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] One embodiment of this application provides a lead-free ceramic, mainly comprising the chemical formula (1-x)(K y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-bThe main component is represented by ZrO3)-cMnO2, where x, y, a, and b represent the number of particles, 0 ≤ x < 1, 0 < y < 1, 0 < a ≤ 0.97, 0 < b < 1, and c represents the mass percentage of MnO2 in the main component, 0 ≤ c ≤ 1%. (1-x)(K y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3 represents the potassium sodium niobate (KNN) phase, which contains Ta; x(Bi b Na 1-b ZrO3 represents sodium bismuth zirconate (BNZ), and cMnO2 represents the manganese dioxide phase.

[0037] The lead-free ceramics provided in this application mainly include those with the chemical formula (1-x)(K y Na 1-y (Nb) a Sb 0.97- a Ta 0.03 )O3-x(Bi b Na 1-b The main component represented by ZrO3-cMnO2 is a potassium sodium niobate (KNN) phase containing a specific proportion of Ta element in the lead-free ceramic. Through the reasonable proportion of the lead-free ceramic composition, the above-mentioned lead-free ceramic has good piezoelectric properties, and also has better piezoelectric constant, mechanical quality factor and electromechanical coupling coefficient.

[0038] x represents the ratio of potassium sodium niobate (KNN) phase to sodium bismuth zirconate (BNZ) phase in the main component. In some embodiments, 0 ≤ x ≤ 0.08. When x = 0, the main component does not contain the BNZ phase. Further, 0 < x ≤ 0.08 or 0.02 ≤ x ≤ 0.06. The combination of KNN and BNZ phases results in higher d33, electromechanical coupling coefficient Kp, mechanical quality factor Qm, and better piezoelectric properties in the lead-free ceramic. This is because the orthogonal-tetragonal two-phase transition temperature of the lead-free ceramic can be controlled to near room temperature through two-phase composite doping, constructing a polymorphic phase transition (PPT) region where orthogonal-tetragonal two phases coexist at room temperature. Optionally, x = 0, 0.02, 0.04, 0.06, 0.08, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, or 1.

[0039] y represents the ratio of potassium to sodium in the KNN phase. In some embodiments, 0.43 ≤ y ≤ 0.48. When the ratio of potassium to sodium in the KNN phase meets the above condition, the piezoelectric properties of the lead-free ceramic are better. Optionally, y = 0.43, 0.44, 0.45, 0.46, 0.47, or 0.48.

[0040] 'a' represents the ratio of niobium to antimony in the KNN phase. In some embodiments, 0.8 ≤ a ≤ 0.97. Because Sb has a higher electronegativity than Nb, its bond energy with oxygen is larger, leading to enhanced spontaneous polarization of the ceramic, improving its piezoelectric and dielectric properties while reducing dielectric loss. Further, 0.9 ≤ a ≤ 0.97. Optionally, a = 0.8, 0.85, 0.9, 0.95, or 0.97. In the embodiments of this application, a = 0.97, and the KNN phase does not contain antimony.

[0041] b represents the ratio of bismuth to sodium in the BNZ phase. In some embodiments, 0.2 ≤ b ≤ 0.8. When the ratio of bismuth to sodium in the BNZ phase meets the above conditions, the lead-free ceramic exhibits better piezoelectric properties and better temperature stability. Further, 0.5 ≤ b ≤ 0.65. In the embodiments of this application, b = 0.6.

[0042] c represents the mass percentage of MnO2 in the main component. Introducing MnO2 can improve the piezoelectric properties of the lead-free ceramics in the embodiments of this application; however, excessive MnO2 content can introduce excessive impurities, thus degrading the piezoelectric properties of the lead-free ceramics. In some embodiments, 0.2% ≤ c ≤ 0.8% or 0.4% ≤ c ≤ 0.8%. Controlling the MnO2 content within the above range not only improves the piezoelectric properties of the lead-free ceramics but also helps to increase the sintering density of the lead-free ceramics. Optionally, c = 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, or 0.8%.

[0043] In some embodiments, 0.02≤x≤0.06, 0.43≤y≤0.48, 0.9≤a≤0.97, 0.5≤b≤0.65, and 0.4%≤c≤0.8%. The composition of the main components is controlled to meet the above conditions. The lead-free ceramic contains a specific ratio of KNN phase, BNZ phase, and MnO2. The lead-free ceramic exhibits good piezoelectric properties, with a high piezoelectric constant d33, mechanical quality factor (Qm), and electromechanical coupling coefficient (Kp), as well as low dielectric loss (tanδ) and impedance.

[0044] In some embodiments, the main component includes 0.94 (K) 0.48 Na 0.52 (Nb) 0.97 Ta 0.03O3-0.06(Bi) 0.6 Na 0.4 ZrO3)-0.6% MnO2, 0.94% K 0.43 Na 0.57 (Nb) 0.97 Ta 0.03 O3-0.06(Bi) 0.6 Na 0.4 ZrO3)-0.5% MnO2 and 0.94% K 0.45 Na 0.55 (Nb) 0.97 Ta 0.03 O3-0.06(Bi) 0.6 Na 0.4 One of ZrO3 and 0.5% MnO2.

[0045] In some embodiments, the mass percentage of the main component in the ceramic is ≥94%. Optionally, the mass percentage of the main component in the lead-free ceramic is within the range of 94%, 95%, 96%, 97%, 98%, 99%, 100%, or any of the above values.

[0046] In some embodiments, the lead-free ceramic further includes a dopant element M, wherein M includes at least one selected from Cu, Sr, Ba, Ca, Zn, La, Li, and Mg. The dopant element M can improve the sintering density of the lead-free ceramic or modify it to enhance its piezoelectric properties.

[0047] In some embodiments, the dopant element M exists in the ceramic in an oxidized state.

[0048] In some embodiments, the mass percentage of each dopant element M in the lead-free ceramic is ≤1%.

[0049] In some embodiments, the sum of the mass percentages of each dopant element M in the lead-free ceramic is ≤5%.

[0050] Excessive dopant content leads to an increase in impurity phases in lead-free ceramics, affecting their piezoelectric properties. Maintaining the mass percentage of dopant elements within the aforementioned range results in superior piezoelectric properties for lead-free ceramics.

[0051] Another embodiment of this application also provides a piezoelectric ceramic, which includes a ceramic body and an electrode located on the ceramic body, wherein the ceramic body is a lead-free ceramic of any of the above embodiments.

[0052] In some embodiments, the piezoelectric ceramic has a piezoelectric constant d33 of 100 pC / N to 315 pC / N. The dielectric loss is 2.6% to 13.1%. The impedance is 50 Ω to 180 Ω. The mechanical quality factor Qm is 21 to 129. The electromechanical coupling coefficient Kp is 20 to 38.

[0053] The aforementioned piezoelectric ceramics include the aforementioned lead-free ceramics. The ceramic body does not contain lead and has excellent piezoelectric properties, thus avoiding the potential health risks of lead. It is especially suitable for medical nebulizers.

[0054] In addition, one embodiment of this application also provides a method for preparing the above-mentioned piezoelectric ceramic, which includes the following steps S100 and S200:

[0055] Step S100: Weigh the raw materials according to the composition of lead-free ceramics and prepare the ceramic body using solid-state synthesis method.

[0056] In some embodiments, the raw materials for the main components of the lead-free ceramic include potassium, sodium, niobium, antimony, tantalum, bismuth, zirconium, and manganese sources. In some embodiments, the raw materials for the main components of the lead-free ceramic are at least one of oxides and carbonates containing lead-free ceramic metal elements. Optionally, the potassium source includes at least one of K₂O and K₂CO₃; the sodium source includes at least one of Na₂O and Na₂CO₃; the niobium source includes Nb₂O₅; the antimony source includes Sb₂O₃; the tantalum source includes Ta₂O₅; the bismuth source includes Bi₂O₃; the zirconium source includes ZrO₂; and the manganese source includes MnO₂. It is understood that the raw materials for the main components may be at least one of carbonates and oxides, including but not limited to the substances given above.

[0057] In some embodiments, the lead-free ceramic further includes a dopant element M, wherein M includes at least one of Cu, Sr, Ba, Ca, Zn, La, Li and Mg; the dopant element M is made from at least one of oxides, nitrates and carbonates.

[0058] Optionally, the raw material for doping Cu includes CuO. The raw material for doping Sr includes SrCO3. The raw material for doping Ba includes BaCO3. The raw material for doping Ca includes CaCO3. The raw material for doping Zn includes ZnO. The raw material for doping La includes La2O3. The raw material for doping Li includes Li2CO3. The raw material for doping Mg includes MgO.

[0059] In some embodiments, the steps of weighing raw materials according to the composition of lead-free ceramics and preparing the ceramic body using a solid-state synthesis method include steps S110 and S120:

[0060] Step S110: Weigh the raw materials according to the composition of lead-free ceramics, grind the raw materials and pre-fire them to prepare ceramic powder.

[0061] Specifically, the raw materials are weighed according to the composition of lead-free ceramics, wherein the raw materials of the main components can be weighed based on their chemical formulas.

[0062] In some embodiments, a drying process is included before weighing the raw materials. Specifically, the drying temperature is 100°C to 150°C, and the drying time is 2 hours to 5 hours.

[0063] Optionally, the grinding method is ball milling. In some embodiments, the grinding method is dry grinding, and in other embodiments, the grinding method is wet grinding. In some embodiments, the grinding time is 12h to 24h.

[0064] Optionally, the pre-firing temperature is 850℃~930℃. The pre-firing holding time is 2h~5h.

[0065] In some embodiments, the steps for preparing ceramic powder include: mixing raw materials with grinding zirconium balls and anhydrous ethanol, ball milling, drying, and preparing a premix that can pass through a 60-mesh sieve; keeping the prepared premix at 850℃~930℃ for 2h~5h to prepare a pre-fired product; pulverizing the pre-fired product, mixing it with grinding zirconium balls and anhydrous ethanol, ball milling, and then drying, to prepare ceramic powder that can pass through a 60-mesh sieve.

[0066] Step S120: Granulate, shape, remove binders and sinter the ceramic powder to prepare lead-free ceramics.

[0067] Specifically, the granulation, molding, debinding, and sintering processes are not particularly limited and can be selected and adjusted according to actual needs. Optionally, the ceramic powder obtained in step S110 is processed by manual granulation or spray granulation to prepare granulated powder. The granulated powder is placed in a mold and pressed to prepare a ceramic green body. The ceramic green body is debinded at 600℃~750℃. The ceramic green body after debinding is sintered at 1050℃~1250℃ to prepare the ceramic body. In some embodiments, the debinding time is 1h~5h. The sintering holding time is 1h~5h.

[0068] Step S200: Prepare electrodes on the ceramic body to prepare piezoelectric ceramic.

[0069] Specifically, the ceramic body is ground, and electrodes and polarization electrodes are prepared to fabricate piezoelectric ceramics. There are no particular limitations on the chamfering, grinding, electrode preparation, and polarization electrode processes; they can be selected and adjusted according to actual needs.

[0070] Optionally, step S200 includes the following steps S210, S220 and S230.

[0071] Step S210: Polish the ceramic body to prepare a ceramic body with a smooth and flat surface.

[0072] Step S220: The surface of the smooth ceramic body obtained in step S210, with screen-printed electrodes, is sintered at 750℃ to 850℃ to prepare a ceramic body with electrodes. Specifically, there are no particular limitations on the electrode material; electrode materials known in the art can be used, such as elemental metals or alloys. For example, the electrode material can be silver. In some embodiments, the sintering holding time is 1h to 1.5h.

[0073] Step S230: The ceramic body with electrodes is placed in a DC electric field to polarize it, thus preparing a piezoelectric ceramic.

[0074] Optionally, in step S230, the polarization field strength is 3kV / mm to 5kV / mm, the polarization time is 15min to 30min, and the polarization temperature is 100℃ to 130℃.

[0075] The above-mentioned method for preparing piezoelectric ceramics is simple to operate and conducive to large-scale production. The piezoelectric ceramics prepared by the above method do not contain lead, avoiding potential risks to human health, and have high piezoelectric constant, mechanical quality factor and electromechanical coupling coefficient, as well as low dielectric loss and impedance, exhibiting excellent piezoelectric performance.

[0076] Furthermore, another embodiment of this application provides a ceramic powder, mainly comprising the following components: (1-x)(K y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b The main component is represented by ZrO3-cMnO2, where x, y, a, and b represent the number of particles, 0 ≤ x < 1, 0 < y < 1, 0 < a ≤ 0.97, 0 < b < 1, and c represents the mass percentage of MnO2 in the main component, 0 ≤ c ≤ 1%.

[0077] In some embodiments, the particle size of the ceramic powder is ≤60 mesh. Optionally, the ceramic powder is obtained by step S110 in the method for preparing the ceramic described above.

[0078] The above-mentioned ceramic powder can be used to prepare piezoelectric ceramics. The piezoelectric ceramics prepared using the above-mentioned ceramic powder do not contain lead, thus avoiding potential risks to human health. They also have high piezoelectric constant, mechanical quality factor and electromechanical coupling coefficient, as well as low dielectric loss and impedance, resulting in better piezoelectric performance.

[0079] Another embodiment of this application provides an atomizing device, including the piezoelectric ceramic described above.

[0080] In some embodiments, the nebulizer further includes a power source electrically connected to the electrodes of the piezoelectric ceramic to supply power to the piezoelectric ceramic. Specifically, the aforementioned nebulizer is a medical nebulizer.

[0081] The aforementioned atomizing device includes the aforementioned piezoelectric ceramic. The piezoelectric ceramic does not contain lead, thus avoiding potential risks to human health. Furthermore, the piezoelectric ceramic has excellent piezoelectric properties, which can meet the usage requirements of the atomizing device.

[0082] The following detailed description is provided with reference to specific embodiments. Unless otherwise specified, the embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the reagents and instruments used in the embodiments are conventionally selected in the art. Experimental methods not specifying specific conditions in the embodiments were performed under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer. In the following embodiments, "wt%" represents mass percentage. All materials used below are of analytical purity or higher.

[0083] Example 1

[0084] Please refer to Table 1. The piezoelectric ceramic of this embodiment includes a ceramic body and electrodes located on the ceramic body, and the electrodes are polarized. The composition of the ceramic body is expressed as (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 )O3-x(Bi b Na 1-b ZrO3)-cMnO2, where x=0, y=0.48, a=0.97, c=0.

[0085] Specifically, the preparation method of piezoelectric ceramics in this embodiment includes the following steps:

[0086] (1) Ingredients: K2CO3, Na2CO3, Nb2O5, Sb2O3, Ta2O5, Bi2O3, ZrO2, and MnO2 were used as raw materials. After weighing the raw materials according to the composition of the ceramic body, they were placed in a container. Grinding zirconium balls were added at a mass ratio of 1:2, followed by 2% anhydrous ethanol of the total mass of the mixture. The mixture here refers to the total amount of raw materials weighed according to the composition of the ceramic body.

[0087] (2) Ball milling: The mixture of the above-prepared mixture and anhydrous ethanol is subjected to planetary ball milling at a speed of 300 r / min for 24 h.

[0088] (3) Drying: Dry the powder obtained by ball milling in step (2) at 100°C, then pass it through a 60-mesh sieve and take the sieve material for later use.

[0089] (4) Pre-calcination: The powder after sieving in step (3) is pre-calcined in a muffle furnace at 900°C for 4 hours.

[0090] (5) Ball milling: The powder after pre-calcination in step (4) is crushed in a crusher, passed through a 60-mesh sieve, and then ball milled in a planetary ball mill: Grinding balls are added in a mass ratio of powder to grinding balls = 1:2, and 2% anhydrous ethanol of the powder mass is added. The rotation speed is 300 r / min and the ball milling time is 12 h.

[0091] (6) Dry the ball-milled powder from step (5) at 100°C, then pass it through a 60-mesh sieve and take the sieve-passing material as ceramic powder for later use.

[0092] (7) Granulation: The ceramic powder obtained in step (6) is subjected to spray granulation treatment to obtain granulated powder.

[0093] (8) Molding: The granulated powder obtained in step (7) is pressed into a ring mold to obtain a ceramic green body with a thickness of 1 mm.

[0094] (9) Debinding: Debinding the ceramic green body obtained in step (8) in a resistance furnace at 700°C for 3 hours.

[0095] (10) Sintering: The ceramic green body after the glue removal in step (9) is placed in a resistance furnace and sintered at 1200℃ for 3 hours to obtain the ceramic body.

[0096] (11) Polishing: Polish the ceramic body obtained in step (10) to ensure that it is flat, smooth and uniform.

[0097] (12) Electrode preparation: The ceramic body polished in step (11) is cleaned, silver is screen printed, and then silver is fired in a heating furnace at 800°C for 1 hour to obtain a ceramic body with electrodes.

[0098] (13) Polarization: The ceramic body with electrodes is placed in a DC electric field for polarization. The polarization field strength is 4KV / mm, the polarization time is 20min, and the polarization temperature is 100℃ to obtain the polarized ceramic body.

[0099] (14) The polarized ceramic body is aged for 24 hours to obtain piezoelectric ceramic.

[0100] The piezoelectric ceramic of this embodiment was tested using a d33 tester and an impedance analyzer. The results were: d33 = 140 pC / N, dielectric loss of 5.5%, and impedance of 120 Ω. Further calculations yielded an electromechanical coupling coefficient kp of 31.6 and a mechanical quality factor (Q). m The value is 30.

[0101] Example 2

[0102] Please refer to Table 1. The structure and preparation method of the piezoelectric ceramic in this embodiment are roughly the same as those in Example 1. The difference is that the composition of the ceramic body is expressed as (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b ZrO3)-cMnO2, where x = 0.02, y = 0.48, a = 0.97, b = 0.6, c = 0.

[0103] The performance parameters of the piezoelectric ceramic in this embodiment were tested and calculated using a d33 tester, impedance analyzer, and dielectric temperature spectrometer. The results are: d33 = 200 pC / N, dielectric loss of 4.8%, and impedance of 100 Ω. Further calculations yielded an electromechanical coupling coefficient kp of 31.2 and a mechanical quality factor (Q). m The value is 33.

[0104] Example 3

[0105] Please refer to Table 1. The structure and preparation method of the piezoelectric ceramic in this embodiment are roughly the same as those in Example 1. The difference is that the composition of the ceramic body is expressed as (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b ZrO3)-cMnO2, where x = 0.06, y = 0.48, a = 0.97, b = 0.6, c = 0.

[0106] The performance parameters of the piezoelectric ceramic in this embodiment were tested and calculated using a d33 meter, impedance analyzer, and dielectric temperature spectrometer. The results are: d33 = 260 pC / N, dielectric loss of 4.5%, and impedance of 90 Ω. Further calculations yielded an electromechanical coupling coefficient kp of 32.6 and a mechanical quality factor (Q). m The value is 35.

[0107] Example 4

[0108] Please refer to Table 1. The structure and preparation method of the piezoelectric ceramic in this embodiment are roughly the same as those in Example 1. The difference is that the composition of the ceramic body is expressed as (1-x)(K) y Na 1-y (Nb) a Sb 0.97-aTa 0.03 O3-x(Bi) b Na 1-b ZrO3)-cMnO2, where x = 0.06, y = 0.48, a = 0.97, b = 0.6, c = 0.2%.

[0109] The performance parameters of the piezoelectric ceramic in this embodiment were tested and calculated using a d33 tester, impedance analyzer, and dielectric temperature spectrometer. The results are: d33 = 280 pC / N, dielectric loss is 2.9%, and impedance is 85 Ω. Further calculations yielded an electromechanical coupling coefficient kp of 32.4 and a mechanical quality factor (Q). m The value is 80.

[0110] Example 5

[0111] Please refer to Table 1. The structure and preparation method of the piezoelectric ceramic in this embodiment are roughly the same as those in Example 1. The difference is that the composition of the ceramic body is expressed as (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b ZrO3)-cMnO2, where x = 0.06, y = 0.48, a = 0.97, b = 0.6, c = 0.6%.

[0112] The performance parameters of the piezoelectric ceramic in this embodiment were tested and calculated using a d33 meter, impedance analyzer, and dielectric temperature spectrometer. The results are: d33 = 295 pC / N, dielectric loss is 1.8%, and impedance is 53 Ω. Further calculations yielded an electromechanical coupling coefficient kp of 36.9 and a mechanical quality factor (Q). m The value is 109.

[0113] Example 6

[0114] Please refer to Table 1. The structure and preparation method of the piezoelectric ceramic in this embodiment are roughly the same as those in Example 1. The difference is that the composition of the ceramic body is expressed as (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b ZrO3)-cMnO2, where x = 0.06, y = 0.48, a = 0.97, b = 0.6, c = 0.8%.

[0115] The performance parameters of the piezoelectric ceramic in this embodiment were tested and calculated using a d33 tester, impedance analyzer, and dielectric temperature spectrometer. The results are: d33 = 255 pC / N, dielectric loss is 1.7%, and impedance is 87 Ω. Further calculations yielded an electromechanical coupling coefficient kp of 32.9 and a mechanical quality factor (Q). m The value is 129.

[0116] Example 7

[0117] Please refer to Table 1. The structure and preparation method of the piezoelectric ceramic in this embodiment are roughly the same as those in Example 1. The difference is that the composition of the ceramic body is expressed as (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b ZrO3)-cMnO2, where x = 0.06, y = 0.43, a = 0.97, b = 0.6, c = 0.5%.

[0118] The performance parameters of the piezoelectric ceramic in this embodiment were tested and calculated using a d33 meter, impedance analyzer, and dielectric temperature spectrometer. The results are: d33 = 300 pC / N, dielectric loss is 1.9%, and impedance is 60 Ω. Further calculations yielded an electromechanical coupling coefficient kp of 35 and a mechanical quality factor (Q). m The value is 115.

[0119] Example 8:

[0120] Please refer to Table 1. The structure and preparation method of the piezoelectric ceramic in this embodiment are roughly the same as those in Example 1. The difference is that the composition of the ceramic body is expressed as (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b ZrO3)-cMnO2, where x = 0.06, y = 0.45, a = 0.97, b = 0.6, c = 0.5%.

[0121] The performance parameters of the piezoelectric ceramic in this embodiment were tested and calculated using a d33 meter, impedance analyzer, and dielectric temperature spectrometer. The results are: d33 = 315 pC / N, dielectric loss is 1.7%, and impedance is 50 Ω. Further calculations yielded an electromechanical coupling coefficient kp of 38 and a mechanical quality factor (Q). m The value is 120.

[0122] Examples 9-14:

[0123] Please refer to Table 1. The structure and preparation method of the piezoelectric ceramics in Examples 9-14 are generally the same as those in Example 8, except that the composition of the ceramic body is expressed as (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b ZrO3)-cMnO2, where x, y, a, b, and c are adjusted according to Table 1.

[0124] Comparative Example 1:

[0125] Please refer to Table 1. The structure and preparation method of the piezoelectric ceramic in this comparative example are roughly the same as those in Example 8. The difference is that the composition of the ceramic body is expressed as K. 0.48 Na 0.52 NbO3.

[0126] Table 1

[0127]

[0128] As can be seen from the relevant data in Table 1, the piezoelectric constant d33 of the piezoelectric ceramics in Examples 1 to 14 is 100pC / N to 315pC / N, the dielectric loss is 2.6% to 13.1%, the impedance is 50Ω to 180Ω, the mechanical quality factor Qm is 21 to 129, and the electromechanical coupling coefficient Kp is 20 to 38. The piezoelectric ceramics in Examples 1 to 14 have good piezoelectric performance and can be used in atomizing devices.

[0129] The difference between the piezoelectric ceramic of Comparative Example 1 and Example 1 is that the piezoelectric ceramic is composed of potassium sodium niobate and does not contain Ta and Sb elements. Compared with the piezoelectric ceramic of Example 1, its piezoelectric performance is reduced.

[0130] As can be seen from Examples 1-3, the piezoelectric ceramics of Examples 2-3 are doped with the BNZ phase, which improves the piezoelectric constant, electromechanical coupling coefficient, and mechanical quality factor compared to Example 1, which contains only the KNN single phase. As can be seen from Examples 8-11, a higher doping level of the BNZ phase reduces the piezoelectric performance of the piezoelectric ceramic.

[0131] As can be seen from Examples 3-6, the introduction of the MnO2 phase improves the piezoelectric properties of piezoelectric ceramics, especially when the concentration is 0.2wt% ≤ c ≤ 0.6wt%, the improvement is significant. This may be because the introduction of the MnO2 phase helps to increase the sintering density of KNN-based piezoelectric ceramics, thereby improving the piezoelectric properties; however, excessive MnO2 can introduce impurity phases during sintering, reducing the piezoelectric properties of the ceramics.

[0132] A comparison of Examples 8-10 shows that in Examples 9 and 10, when x = 0.5 or 0.9, the reduced content of the KNN phase leads to a decrease in the piezoelectric properties of the piezoelectric ceramic, while increasing dielectric loss and impedance. Therefore, in this application, the piezoelectric ceramic exhibits better performance when x ≤ 0.08.

[0133] A comparison of Examples 8 and 11-12 shows that in Examples 11 and 12, where y = 0.1 or 0.9, the piezoelectric properties of the piezoelectric ceramics in Examples 11 and 12 are inferior to those in Example 8. Therefore, in this application, the piezoelectric ceramics exhibit better performance when 0.43 ≤ y ≤ 0.48.

[0134] Among them, the piezoelectric ceramics of Examples 5, 7, and 8 exhibit better piezoelectric properties. (See also...) Figure 1 , Figure 2 The images shown are the X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images of the piezoelectric ceramics in Examples 5, 7, and 8, respectively. Figure 1 , Figure 2 It can be seen that the piezoelectric ceramics of Examples 5, 7 and 8 have basically the same crystal phase; compared with Examples 5 and 7, the piezoelectric ceramic of Example 8 has a higher sintering density.

[0135] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0136] The embodiments described above merely illustrate several implementation methods of this application to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A lead-free ceramic, characterized in that, Including those with the chemical formula (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b The main component is represented by ZrO3-cMnO2, where x, y, a and b represent the number of atoms, 0.02≤x≤0.08, 0.43≤y≤0.48, 0.5≤a≤0.97, b=0.6, and c represents the mass percentage of MnO2 in the main component, 0.2%≤c≤1%.

2. The lead-free ceramic according to claim 1, characterized in that, The lead-free ceramic satisfies at least one of the following conditions (1) to (2): （1）0.8≤a≤0.97； （2）0.2 %≤c≤0.8%。 3. The lead-free ceramic according to claim 1, characterized in that, 0.02≤x≤0.06, 0.43≤y≤0.48, 0.9≤a≤0.97, 0.4%≤c≤0.8%.

4. The lead-free ceramic according to claim 1, characterized in that, The main component includes 0.94 (K) 0.48 Na 0.52 (Nb) 0.97 Ta 0.03 O3-0.06(Bi) 0.6 Na 0.4 ZrO3)-0.6%MnO2, 0.94%K 0.43 Na 0.57 (Nb) 0.97 Ta 0.03 O3-0.06(Bi) 0.6 Na 0.4 ZrO3)-0.5%MnO2 and 0.94%K 0.45 Na 0.55 (Nb) 0.97 Ta 0.03 O3-0.06(Bi) 0.6 Na 0.4 One of ZrO3 and 0.5% MnO2.

5. The lead-free ceramic according to claim 1, characterized in that, The main component in the lead-free ceramic has a mass percentage of 94% to 100%.

6. The lead-free ceramic according to any one of claims 1 to 5, characterized in that, The lead-free ceramic also includes a doping element M, wherein M includes at least one of Cu, Sr, Ba, Ca, Zn, La, Li and Mg.

7. The lead-free ceramic according to claim 6, characterized in that, The mass percentage of each dopant element M in the lead-free ceramic is ≤1%.

8. The lead-free ceramic according to claim 6, characterized in that, The sum of the mass percentages of each of the doping elements M in the lead-free ceramic is ≤5%.

9. A method for preparing lead-free ceramics, characterized in that, Includes the following steps: The lead-free ceramic according to any one of claims 1 to 8 is prepared by weighing raw materials and using a solid-state synthesis method.

10. The method for preparing lead-free ceramics according to claim 9, characterized in that, The steps for preparing lead-free ceramics using a solid-state synthesis method, based on the weighing of raw materials according to the composition of lead-free ceramics, include: According to the composition of the lead-free ceramic, the raw materials are weighed, ground and pre-fired to prepare ceramic powder; and the ceramic powder is granulated, shaped, debinded and sintered to prepare the lead-free ceramic.

11. The method for preparing lead-free ceramics according to claim 9 or 10, characterized in that, The raw materials for the main components of the lead-free ceramic include potassium source, sodium source, niobium source, antimony source, tantalum source, bismuth source, zirconium source and manganese source.

12. The method for preparing lead-free ceramics according to claim 11, characterized in that, The potassium source includes at least one of K2O and K2CO3; the sodium source includes at least one of Na2O and Na2CO3; the niobium source includes Nb2O5; the antimony source includes Sb2O3; the tantalum source includes Ta2O5; the bismuth source includes Bi2O3; the zirconium source includes ZrO2; and the manganese source includes MnO2.

13. The method for preparing lead-free ceramics according to claim 9 or 10, characterized in that, When the lead-free ceramic further includes a dopant element M, the dopant element M is made from at least one of oxides, nitrates and carbonates.

14. A ceramic powder, characterized in that, Including those with the chemical formula (1-x)(K) y Na 1-y (Nb) a Sb 0.97-a Ta 0.03 O3-x(Bi) b Na 1-b The main component is represented by ZrO3-cMnO2, where x, y, a and b represent the number of atoms, 0≤x<1, 0<y<1, 0<a≤0.97, b=0.6, and c represents the mass percentage of MnO2 in the main component, 0.2%≤c≤1%.

15. A piezoelectric ceramic, characterized in that, The piezoelectric ceramic includes a ceramic body and an electrode located on the ceramic body, wherein the ceramic body is the lead-free ceramic as described in any one of claims 1 to 8 or is prepared using the ceramic powder as described in claim 14.

16. An atomizing device, characterized in that, Includes the piezoelectric ceramic as described in claim 15.

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