Lead-free electronic ceramic material and preparation method thereof

Abstract

The present invention relates to the field of electronic ceramic materials, in particular to a lead-free electronic ceramic material and a preparation method thereof, wherein the chemical structure thereof is as follows: x Li y Na 1‑x‑y )(Sb z Nb 1‑z )O3‑αSr2Ga q Mn 1‑q MoO6α, x, y, z, and q are atomic percentages, α is 0.01-0.1, x is 0.3-0.5, y is 0.01-0.1, z is 0.01-0.1, and q is 0.1-0.5. The electronic ceramic material prepared by the present invention has excellent piezoelectric properties, and various properties are far superior to those of pure KNN piezoelectric ceramics.

Description

Technical Field

[0001] The invention relates to the field of electronic ceramic materials, in particular to a lead-free electronic ceramic material and a preparation method thereof. Background Art

[0002] Piezoelectric ceramics are an important type of functional electronic ceramic materials that can convert electrical energy into mechanical energy. Lead zirconate titanate-based piezoelectric ceramics have excellent piezoelectric properties, but the lead in them is harmful to the environment and human health. Potassium sodium niobate-based lead-free piezoelectric ceramics have good piezoelectric properties and are environmentally friendly, and have received great attention. However, the piezoelectric properties of pure phase potassium sodium niobate ceramics are poor, far inferior to lead zirconate titanate-based piezoelectric ceramics. Summary of the invention

[0003] Purpose of the invention: In view of the above technical problems, the present invention proposes a lead-free electronic ceramic material and a preparation method thereof.

[0004] The technical solutions adopted are as follows:

[0005] A lead-free electronic ceramic material, the chemical structure of which is as follows:

[0006] (1-α)(K x Li y Na 1-x-y )(Sb z Nb 1-z )O3-αSr2Ga q Mn 1-q MoO6

[0007] α, x, y, z, and q are atomic percentages;

[0008] α is 0.01-0.1;

[0009] x is 0.3-0.5, y is 0.01-0.1, z is 0.01-0.1, and q is 0.1-0.5.

[0010] Further, α is 0.04-0.06.

[0011] Furthermore, α is 0.05.

[0012] Further, x is 0.35-0.45, y is 0.04-0.06, z is 0.04-0.06, and q is 0.2-0.3.

[0013] Further, x is 0.45, y is 0.05, z is 0.05, and q is 0.25.

[0014] The present invention also provides a method for preparing a lead-free electronic ceramic material, which is as follows:

[0015] S1: Sr2CO3, Ga2O3, MnO and MoO3 are weighed according to the ratio of each element, mixed and ball-milled, dried, pressed, pre-calcined and then crushed to obtain the first powder;

[0016] S2: Li2CO3, K2CO3, Na2CO3, Sb2O3, and Nb2O5 are weighed according to the ratio of each element, mixed, ball-milled, dried, pressed, pre-calcined, and then crushed to obtain a second powder;

[0017] S3: the first powder and the second powder are mixed and then ball-milled again, dried, a binder is added to granulate and then sieved, the obtained granules are pressed into green bodies, the green bodies are transferred to a sintering furnace, the temperature is raised to 600-700°C for debinding for 1-3h in the first stage, and then the temperature is raised to 1250-1300°C for sintering for 2-4h in the second stage;

[0018] There is no order of precedence between S1 and S2.

[0019] Furthermore, the pre-firing temperature in S1 is 900-950° C., and the pre-firing time is 5-10 hours.

[0020] Furthermore, the pre-firing temperature in S2 is 800-900° C., and the pre-firing time is 1-5 hours.

[0021] Furthermore, the first stage heating rate is 1-10°C / min, and the second stage heating rate is 10-50°C / min.

[0022] Furthermore, sintering is performed in a reducing atmosphere.

[0023] Beneficial effects of the present invention:

[0024] The present invention provides a lead-free electronic ceramic material. Li and Sb doping can improve the sintering performance of KNN-based ceramics, effectively control the abnormal growth of grains, and improve the uniformity of grains. A certain content of Sr2Ga q Mn 1-q MoO6 doping can diffuse well into the KNN lattice, making the ceramic grains gradually larger and more evenly distributed, thereby increasing the density, which is beneficial to eliminating the internal stress generated by spontaneous polarization, and helps the domain wall deflection during polarization, thereby improving its piezoelectric properties. The piezoelectric properties are improved after sintering in a reducing atmosphere. This may be because when KNN-based ceramics are sintered in a reducing atmosphere, part of the lattice oxygen will combine with hydrogen to produce water vapor, thereby increasing the oxygen vacancies. These oxygen vacancies can promote the transfer of charges, thereby improving the electrical properties of the electronic ceramic material. The reducing atmosphere can also inhibit grain growth and promote the densification of ceramics. The electronic ceramic material prepared by the present invention has excellent piezoelectric properties, and various properties are far superior to those of pure KNN piezoelectric ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a surface microscopic morphology of the lead-free electronic ceramic material prepared in Example 1. DETAILED DESCRIPTION

[0026] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. The techniques not mentioned in the present invention are all referenced to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0027] Embodiment 1:

[0028] A lead-free electronic ceramic material, the chemical structure of which is as follows:

[0029] 0.95(K 0.45 Li 0.05 Na 0.5 )(Sb 0.05 Nb 0.95 )O3-0.05Sr2Ga 0.25 Mn 0.75 MoO6

[0030] The preparation method of the lead-free electronic ceramic material is as follows:

[0031] Sr2CO3, Ga2O3, MnO and MoO3 were weighed according to the ratio of each element and placed in a ball milling jar, and ball milled for 10 hours using anhydrous ethanol as a ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into sheets under a pressure of 20MPa, and pre-calcined at 950°C for 5 hours, and then crushed to obtain a first powder;

[0032] Li2CO3, K2CO3, Na2CO3, Sb2O3 and Nb2O5 were weighed according to the ratio of each element and placed in a ball milling jar, and ball milled for 10 hours using anhydrous ethanol as the ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into tablets under a pressure of 20MPa, and pre-calcined at 850°C for 5 hours, and then crushed to obtain a second powder;

[0033] The first powder and the second powder are mixed and added into the ball mill again, and the mixture is ball milled for 10 hours in a planetary ball mill with anhydrous ethanol as the ball milling medium, and then dried in an oven at 80°C for 10 hours, and a polyvinyl alcohol solution with a mass concentration of 8wt% is added as a binder to granulate and then sieve. The obtained granules are pressed into a green body at 200MPa, and the green body is transferred to a sintering furnace. After replacing the air in the sintering furnace with a mixed gas composed of hydrogen and argon in a volume ratio of 1:5, the temperature is increased to 650°C at a rate of 1°C / min in one stage to debind for 2 hours, and then the temperature is increased to 1280°C in a second stage at a rate of 25°C / min, sintered for 4 hours, and then cooled to room temperature with the furnace.

[0034] Embodiment 2:

[0035] A lead-free electronic ceramic material, the chemical structure of which is as follows:

[0036] 0.95(K 0.45 Li 0.05 Na 0.5 )(Sb 0.05 Nb 0.95 )O3-0.05Sr2Ga 0.25 Mn 0.75 MoO6

[0037] The preparation method of the lead-free electronic ceramic material is as follows:

[0038] Sr2CO3, Ga2O3, MnO and MoO3 were weighed according to the ratio of each element and placed in a ball milling jar, and ball milled for 10 hours using anhydrous ethanol as a ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into sheets under a pressure of 20MPa, and pre-calcined at 950°C for 10 hours, and then crushed to obtain a first powder;

[0039] Li2CO3, K2CO3, Na2CO3, Sb2O3 and Nb2O5 were weighed according to the ratio of each element and placed in a ball mill, and ball milled for 10 hours using anhydrous ethanol as a ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into tablets under a pressure of 20 MPa, and pre-calcined at 900°C for 1 hour, and then crushed to obtain a second powder;

[0040] The first powder and the second powder are mixed and added into the ball mill again. The mixture is ball milled for 10 hours in a planetary ball mill with anhydrous ethanol as the ball milling medium, and then dried in an oven at 80°C for 10 hours. A polyvinyl alcohol solution with a mass concentration of 8wt% is added as a binder for granulation and then sieved. The obtained granules are pressed into a green body at 200MPa, and the green body is transferred to a sintering furnace. After replacing the air in the sintering furnace with a mixed gas composed of hydrogen and argon in a volume ratio of 1:5, the temperature is increased to 700°C at a speed of 10°C / min in one stage to debind for 3 hours, and then the temperature is increased to 1300°C at a speed of 10°C / min in two stages, sintered for 4 hours, and then cooled to room temperature with the furnace.

[0041] Embodiment 3:

[0042] A lead-free electronic ceramic material, the chemical structure of which is as follows:

[0043] 0.95(K 0.45 Li 0.05 Na 0.5 )(Sb 0.05 Nb 0.95 )O3-0.05Sr2Ga 0.25 Mn 0.75MoO6

[0044] The preparation method of the lead-free electronic ceramic material is as follows:

[0045] Sr2CO3, Ga2O3, MnO and MoO3 were weighed according to the ratio of each element and placed in a ball mill, and ball milled for 10 hours using anhydrous ethanol as a ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into sheets under a pressure of 20 MPa, and pre-calcined at 900°C for 5 hours, and then crushed to obtain a first powder;

[0046] Li2CO3, K2CO3, Na2CO3, Sb2O3 and Nb2O5 were weighed according to the ratio of each element and placed in a ball milling jar, and ball milled for 10 hours using anhydrous ethanol as a ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into tablets under a pressure of 20 MPa, and pre-calcined at 800°C for 1 hour, and then crushed to obtain a second powder;

[0047] The first powder and the second powder are mixed and added into the ball mill again. The mixture is milled for 10 hours in a planetary ball mill with anhydrous ethanol as the milling medium, and then dried in an oven at 80°C for 10 hours. A polyvinyl alcohol solution with a mass concentration of 8wt% is added as a binder to granulate the mixture and then sieve it. The obtained granules are pressed into a green body at 200MPa. The green body is transferred to a sintering furnace. The air in the sintering furnace is replaced with a mixed gas composed of hydrogen and argon in a volume ratio of 1:5. The temperature is increased to 600°C at a rate of 10°C / min in one stage to debind for 2 hours, and then increased to 1250°C at a rate of 50°C / min in two stages, sintered for 2 hours, and then cooled to room temperature with the furnace.

[0048] Comparative Example 1:

[0049] It is basically the same as Example 1, except that its chemical structure is as follows:

[0050] (K 0.45 Li 0.05 Na 0.5 )(Sb 0.05 Nb 0.95 )O3

[0051] The preparation method of the lead-free electronic ceramic material is as follows:

[0052] Li2CO3, K2CO3, Na2CO3, Sb2O3 and Nb2O5 were weighed according to the ratio of each element and placed in a ball mill. After being ball milled for 10 hours using anhydrous ethanol as the ball milling medium in a planetary ball mill, the mixture was dried in an oven at 80°C for 10 hours, pressed into tablets under a pressure of 20 MPa, and pre-calcined at 850°C for 5 hours before being crushed to obtain a powder.

[0053] After mixing the powder, add it into the ball mill again, mill it for 10 hours in a planetary ball mill with anhydrous ethanol as the ball milling medium, and then dry it in an oven at 80°C for 10 hours. Add a polyvinyl alcohol solution with a mass concentration of 8wt% as a binder to granulate it and then sieve it. The obtained granules are pressed into a green body at 200MPa, and the green body is transferred to a sintering furnace. After replacing the air in the sintering furnace with a mixed gas composed of hydrogen and argon in a volume ratio of 1:5, the temperature is increased to 650°C at a speed of 1°C / min in one stage to debind for 2 hours, and then the temperature is increased to 1280°C at a speed of 25°C / min in a second stage, sintered for 4 hours, and then cooled to room temperature with the furnace.

[0054] Comparative Example 2:

[0055] The same as Example 1, except that a lead-free electronic ceramic material, whose chemical structure is as follows:

[0056] 0.95(K 0.5 Na 0.5 )NbO3-0.05Sr2Ga 0.25 Mn 0.75 MoO6

[0057] The preparation method of the lead-free electronic ceramic material is as follows:

[0058] Sr2CO3, Ga2O3, MnO and MoO3 were weighed according to the ratio of each element and placed in a ball milling jar, and ball milled for 10 hours using anhydrous ethanol as a ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into sheets under a pressure of 20MPa, and pre-calcined at 950°C for 5 hours, and then crushed to obtain a first powder;

[0059] K2CO3, Na2CO3, and Nb2O5 were weighed according to the ratio of each element and placed in a ball mill, and ball milled for 10 hours using anhydrous ethanol as the ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into sheets under a pressure of 20 MPa, and pre-calcined at 850°C for 5 hours, and then crushed to obtain a second powder;

[0060] The first powder and the second powder are mixed and added into the ball mill again, and the mixture is ball milled for 10 hours in a planetary ball mill with anhydrous ethanol as the ball milling medium, and then dried in an oven at 80°C for 10 hours, and a polyvinyl alcohol solution with a mass concentration of 8wt% is added as a binder to granulate and then sieve. The obtained granules are pressed into a green body at 200MPa, and the green body is transferred to a sintering furnace. After replacing the air in the sintering furnace with a mixed gas composed of hydrogen and argon in a volume ratio of 1:5, the temperature is increased to 650°C at a rate of 1°C / min in one stage to debind for 2 hours, and then the temperature is increased to 1280°C in a second stage at a rate of 25°C / min, sintered for 4 hours, and then cooled to room temperature with the furnace.

[0061] Comparative Example 3:

[0062] It is basically the same as Example 1, except that it is sintered in an air atmosphere. Its chemical structure is as follows:

[0063] 0.95(K 0.45 Li 0.05 Na 0.5 )(Sb 0.05 Nb 0.95 )O3-0.05Sr2Ga 0.25 Mn 0.75 MoO6

[0064] The preparation method of the lead-free electronic ceramic material is as follows:

[0065] Sr2CO3, Ga2O3, MnO and MoO3 were weighed according to the ratio of each element and placed in a ball milling jar, and ball milled for 10 hours using anhydrous ethanol as a ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into sheets under a pressure of 20MPa, and pre-calcined at 950°C for 5 hours, and then crushed to obtain a first powder;

[0066] Li2CO3, K2CO3, Na2CO3, Sb2O3 and Nb2O5 were weighed according to the ratio of each element and placed in a ball milling jar, and ball milled for 10 hours using anhydrous ethanol as the ball milling medium in a planetary ball mill, and then dried in an oven at 80°C for 10 hours, pressed into tablets under a pressure of 20MPa, and pre-calcined at 850°C for 5 hours, and then crushed to obtain a second powder;

[0067] The first powder and the second powder are mixed and added into the ball mill again. The mixture is milled for 10 hours in a planetary ball mill using anhydrous ethanol as the milling medium, and then dried in an oven at 80°C for 10 hours. A polyvinyl alcohol solution with a mass concentration of 8wt% is added as a binder to granulate the mixture and then sieve the granules. The obtained granules are pressed into a green body at 200MPa. The green body is transferred to a sintering furnace. In an air atmosphere, the temperature is increased to 650°C at a rate of 1°C / min in one stage to debind for 2 hours, and then the temperature is increased to 1280°C in a second stage at a rate of 25°C / min, sintered for 4 hours, and then cooled to room temperature with the furnace.

[0068] Performance Test:

[0069] The KNN-based lead-free piezoelectric ceramic materials prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 were polished, and then silver paste was brushed on the upper and lower surfaces, and then cured at 600° C. for 30 min, and then immersed in silicone oil at 70° C. and polarized with a DC electric field of 3 kv / mm for 30 min as samples for performance testing;

[0070] Use ZJ-3A quasi-static d 33The tester measures the piezoelectric constant of the sample, and uses Agilent's HP4192 precision impedance analyzer to test the dielectric loss tanδ, resonant frequency, anti-resonant frequency and corresponding impedance of the sample, and calculates the electromechanical coupling coefficient k of the sample. p and mechanical quality factor Q m ;

[0071] The test results are shown in Table 1 below:

[0072] Table 1:

[0073]

[0074] It can be seen from Table 1 above that the electronic ceramic material prepared by the present invention has excellent piezoelectric properties, and various properties are far superior to those of pure KNN piezoelectric ceramics.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lead-free electronic ceramic material, characterized in that: Its chemical structure is as follows: (1-α)(K x Li y And 1-x-y )(Sb z Nb 1-z )O3-αSr2Ga q Mn 1-q MoO6 α, x, y, z, and q are atomic percentages; α is 0.01-0.1; x is 0.3-0.5, y is 0.01-0.1, z is 0.01-0.1, and q is 0.1-0.

5.

2. The lead-free electronic ceramic material according to claim 1, characterized in that: α is 0.04-0.

06.

3. The lead-free electronic ceramic material according to claim 1, characterized in that: α is 0.

05.

4. The lead-free electronic ceramic material according to claim 1, characterized in that: x is 0.35-0.45, y is 0.04-0.06, z is 0.04-0.06, and q is 0.2-0.

3.

5. The lead-free electronic ceramic material according to claim 1, characterized in that: x is 0.45, y is 0.05, z is 0.05, and q is 0.

25.

6. A method for preparing a lead-free electronic ceramic material according to any one of claims 1 to 5, characterized in that: The details are as follows: S1: Sr2CO3, Ga2O3, MnO and MoO3 are weighed according to the ratio of each element, mixed and ball-milled, dried, pressed, pre-calcined and then crushed to obtain the first powder; S2: Li2CO3, K2CO3, Na2CO3, Sb2O3, and Nb2O5 are weighed according to the ratio of each element, mixed, ball-milled, dried, pressed, pre-calcined, and then crushed to obtain a second powder; S3: the first powder and the second powder are mixed and then ball-milled again, dried, a binder is added to granulate and then sieved, the obtained granules are pressed into green bodies, the green bodies are transferred to a sintering furnace, the temperature is raised to 600-700°C for debinding for 1-3h in the first stage, and then the temperature is raised to 1250-1300°C for sintering for 2-4h in the second stage; There is no order of precedence between S1 and S2.

7. The method for preparing a lead-free electronic ceramic material according to claim 6, characterized in that: The pre-firing temperature in S1 is 900-950°C, and the pre-firing time is 5-10h.

8. The method for preparing a lead-free electronic ceramic material according to claim 6, characterized in that: The pre-firing temperature in S2 is 800-900°C, and the pre-firing time is 1-5h.

9. The method for preparing a lead-free electronic ceramic material according to claim 6, characterized in that: The heating rate of the first stage is 1-10℃ / min, and the heating rate of the second stage is 10-50℃ / min.

10. The method for preparing a lead-free electronic ceramic material according to claim 6, characterized in that: Sintering is carried out in a reducing atmosphere.

Images