A barium titanate-based electronic ceramic and its preparation method
By introducing La1-yAyMnO3 and transition metal oxide combinations into barium titanate ceramics, a composite system is formed, which solves the problems of piezoelectric properties and temperature stability of barium titanate ceramics, improves its piezoelectric properties and Curie temperature, and realizes the More extensive application potential.
Patent Information
- Application Number
- CN202411475835.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-22
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2044-10-22
AI Technical Summary
The piezoelectric properties of barium titanate ceramics have medium piezoelectric properties, low Curie temperature, narrow working temperature zone, and unstable performance parameters with time and temperature changes, making them less common in piezoelectric ceramic applications.
Barium titanate-based electronic ceramics with chemical structural formula (1-x)BaTiO3-xLa1-yAyMnO3-αwt% sintering additives are doped by A (such as Sr and Co) and combined with transition metal oxides (such as CuO, Fe2O3) , form a composite system, improve its piezoelectric properties and temperature stability, and improve density through a specific sintering process.
The piezoelectric performance improvement and Curie temperature improvement of barium titanate electronic ceramics have been achieved, forming a stable perovskite structure, enhancing its application potential at high temperatures.
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Figure CN118978398B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of electronic ceramic materials, in particular to a barium titanate-based electronic ceramic and a preparation method thereof. Background Art
[0002] In 1947, Roberts discovered that when a high DC bias was applied to barium titanate ceramics, the ceramics would exhibit a strong piezoelectric effect. This effect continued to appear even after the voltage was removed, thus opening the prelude to the application of piezoelectric ceramics. At present, lead-free piezoelectric ceramics are mainly divided into perovskite, bismuth-containing layered and tungsten bronze structures according to their crystal structure.
[0003] The crystal of barium titanate belongs to the perovskite structure. As the earliest discovered piezoelectric ceramic, it is now one of the important materials for manufacturing capacitors. However, the application of piezoelectric ceramics is rare, mainly because the piezoelectric performance of barium titanate ceramics is only at a medium level (d 33 About 190pC / N), the Curie temperature is low (Tc=about 120℃), the operating temperature range is narrow, and the stability of performance parameters over time and temperature is poor. Summary of the invention
[0004] Purpose of the invention: In view of the above technical problems, the present invention proposes a barium titanate-based electronic ceramic and a preparation method thereof.
[0005] The technical solutions adopted are as follows:
[0006] A barium titanate electronic ceramic, the chemical structure of which is as follows:
[0007] (1-x)BaTiO 3 -xLa 1-y A y MnO 3 -αwt% sintering aid
[0008] 0.05≤x≤0.25, 0.01≤y≤0.1, 0<α≤10;
[0009] Wherein, x and y are mole fractions, and αwt% represents the mass percentage of the sintering aid in the barium titanate-based electronic ceramics;
[0010] A is Sr and / or Co;
[0011] The sintering aid is a transition metal oxide.
[0012] Furthermore, the transition metal oxide is CuO, ZnO, Fe 2 O 3 Any one or more combinations of .
[0013] Furthermore, the transition metal oxide includes CuO and Fe2 O 3 ;
[0014] The CuO and Fe 2 O 3 The weight ratio is 1-5:1-5.
[0015] Furthermore, A is Sr.
[0016] Furthermore, 0.1≤x≤0.2, 0.04≤y≤0.06, 1≤α≤3.
[0017] Further, x=0.15, y=0.05, α=2.
[0018] The present invention also provides a method for preparing barium titanate-based electronic ceramics:
[0019] BaCO 3 、TiO 2 ,La 2 O 3 、ACO 3 、MnO 2 After mixing with sintering aid, ball milling is carried out, drying, pre-sintering, adding binder to granulate, sieving and pressing to obtain a green body. The green body is heated to 600-650℃, kept warm for 1-3h to remove binder, then continued to heat to 1350-1450℃ and kept warm for sintering for 2-4h, cooled to 1000-1050℃ and kept warm for annealing for 1-3h, and then cooled to room temperature with the furnace.
[0020] Furthermore, the pre-firing temperature is 900-950° C., and the pre-firing time is 1-3 hours.
[0021] Furthermore, the binder is a polyvinyl alcohol solution or a polyvinyl butyral solution.
[0022] Furthermore, the heating rate during sintering is 10-30°C / min, and the cooling rate is 1-5°C / min.
[0023] Beneficial effects of the present invention:
[0024] The present invention provides a barium titanate electronic ceramic, BaTiO 3 and La 1-y A y MnO 3 A binary solid solution system can be formed by compounding. This system has a more stable perovskite structure and constructs a quasi-modular phase boundary with two phases coexisting similar to the PZT system. At the quasi-modular phase boundary, better piezoelectric properties and higher Curie temperature can be obtained. A is doped into LaMnO 3It can replace some La ions and cause lattice distortion, which can further improve the piezoelectric properties and temperature stability of electronic ceramics. The sintering aid can form a liquid phase during the sintering process and fill in the grain boundaries to reduce the sintering temperature and improve the density of electronic ceramics. After testing, the barium titanate electronic ceramics prepared by the invention have good piezoelectric properties and a high Curie temperature. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is the SEM image of the barium titanate electronic ceramic 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 barium titanate electronic ceramic, the chemical structure of which is as follows:
[0029] 0.85BaTiO 3 -0.15La 0.95 Sr 0.05 MnO 3 -1wt%CuO-1wt%Fe 2 O 3；
[0030] The preparation method of the above-mentioned barium titanate electronic ceramic is as follows:
[0031] BaCO 3 、TiO 2 ,La 2 O 3 、SrCO 3 、MnO 2 , CuO, Fe 2 O 3The mixture was added into the ball mill of a planetary ball mill, and deionized water was used as the ball milling medium. The mixture was ball milled for 10 hours at a ratio of ball: material: deionized water = 1:1:1, and then dried in an oven at 80°C for 24 hours to obtain a mixed powder. The mixed powder was pre-sintered at 950°C in a sintering furnace for 2 hours, and a polyvinyl alcohol solution with a mass concentration of 5% was added as a binder for granulation. After passing through a 100-mesh sieve, the green body was pressed under a pressure of 50 MPa to obtain the green body. The green body was heated to 650°C at a rate of 15°C / min in a sintering furnace, kept warm for 2 hours for debinding, and then continued to be heated to 1380°C at a rate of 10°C / min and kept warm for sintering for 4 hours. The mixture was cooled to 1050°C at a rate of 1°C / min, kept warm for annealing for 1 hour, and then cooled to room temperature with the furnace.
[0032] Embodiment 2:
[0033] A barium titanate electronic ceramic, the chemical structure of which is as follows:
[0034] 0.85BaTiO 3 -0.15La 0.95 Sr 0.05 MnO 3 -1.5wt%CuO-0.5wt%Fe 2 O 3；
[0035] The preparation method of the above-mentioned barium titanate electronic ceramic is as follows:
[0036] BaCO 3 、TiO 2 ,La 2 O 3 、SrCO 3 、MnO 2 , CuO, Fe 2 O 3 The mixture was added into the ball mill of a planetary ball mill, and deionized water was used as the ball milling medium. The mixture was ball milled for 10 hours at a ratio of ball: material: deionized water = 1:1:1, and then dried in an oven at 80°C for 24 hours to obtain a mixed powder. The mixed powder was pre-sintered at 950°C in a sintering furnace for 2 hours, and a polyvinyl alcohol solution with a mass concentration of 5% was added as a binder for granulation. After passing through a 100-mesh sieve, the green body was pressed under a pressure of 50 MPa to obtain the green body. The green body was heated to 650°C at a rate of 15°C / min in a sintering furnace, kept warm for 2 hours for debinding, and then continued to be heated to 1380°C at a rate of 10°C / min and kept warm for sintering for 4 hours. The mixture was cooled to 1050°C at a rate of 1°C / min, kept warm for annealing for 1 hour, and then cooled to room temperature with the furnace.
[0037] Embodiment 3:
[0038] A barium titanate electronic ceramic, the chemical structure of which is as follows:
[0039] 0.85BaTiO 3 -0.15La 0.95 Sr 0.05 MnO 3 -0.5wt%CuO-1.5wt%Fe 2 O 3
[0040] The preparation method of the above-mentioned barium titanate electronic ceramic is as follows:
[0041] BaCO 3 、TiO 2 ,La 2 O 3 、SrCO 3 、MnO 2 , CuO, Fe 2 O 3 The mixture was added into the ball mill of a planetary ball mill, and deionized water was used as the ball milling medium. The mixture was ball milled for 10 hours at a ratio of ball: material: deionized water = 1:1:1, and then dried in an oven at 80°C for 24 hours to obtain a mixed powder. The mixed powder was pre-sintered at 950°C in a sintering furnace for 2 hours, and a polyvinyl alcohol solution with a mass concentration of 5% was added as a binder for granulation. After passing through a 100-mesh sieve, the green body was pressed under a pressure of 50 MPa to obtain the green body. The green body was heated to 650°C at a rate of 15°C / min in a sintering furnace, kept warm for 2 hours for debinding, and then continued to be heated to 1380°C at a rate of 10°C / min and kept warm for sintering for 4 hours. The mixture was cooled to 1050°C at a rate of 1°C / min, kept warm for annealing for 1 hour, and then cooled to room temperature with the furnace.
[0042] Embodiment 4:
[0043] A barium titanate electronic ceramic, the chemical structure of which is as follows:
[0044] 0.85BaTiO 3 -0.15La 0.95 Sr 0.05 MnO 3 -2wt%CuO
[0045] The preparation method of the above-mentioned barium titanate electronic ceramic is as follows:
[0046] BaCO 3 、TiO 2 ,La 2 O 3 、SrCO 3 、MnO 2, CuO are added to the ball mill jar of a planetary ball mill, deionized water is used as the ball milling medium, and the mixture is ball milled for 10 hours at a ratio of ball: material: deionized water = 1:1:1, and then dried in an oven at 80°C for 24 hours to obtain a mixed powder. The mixed powder is pre-sintered at 950°C in a sintering furnace for 2 hours, and a polyvinyl alcohol solution with a mass concentration of 5% is added as a binder to granulate the mixture. After passing through a 100-mesh sieve, the mixture is pressed at a pressure of 50 MPa to obtain a green body. The green body is heated to 650°C at a rate of 15°C / min in a sintering furnace, kept warm for 2 hours for debinding, and then continued to be heated to 1380°C at a rate of 10°C / min and kept warm for sintering for 4 hours, and then cooled to 1050°C at a rate of 1°C / min for annealing for 1 hour, and then cooled to room temperature with the furnace.
[0047] Embodiment 5:
[0048] A barium titanate electronic ceramic, the chemical structure of which is as follows:
[0049] 0.85BaTiO 3 -0.15La 0.95 Sr 0.05 MnO 3 -2wt%Fe 2 O 3
[0050] The preparation method of the above-mentioned barium titanate electronic ceramic is as follows:
[0051] BaCO 3 、TiO 2 ,La 2 O 3 、SrCO 3 、MnO 2 , Fe 2 O 3 The mixture was added into the ball mill of a planetary ball mill, and deionized water was used as the ball milling medium. The mixture was ball milled for 10 hours at a ratio of ball: material: deionized water = 1:1:1, and then dried in an oven at 80°C for 24 hours to obtain a mixed powder. The mixed powder was pre-sintered at 950°C in a sintering furnace for 2 hours, and a polyvinyl alcohol solution with a mass concentration of 5% was added as a binder for granulation. After passing through a 100-mesh sieve, the green body was pressed under a pressure of 50 MPa to obtain the green body. The green body was heated to 650°C at a rate of 15°C / min in a sintering furnace, kept warm for 2 hours for debinding, and then continued to be heated to 1380°C at a rate of 10°C / min and kept warm for sintering for 4 hours. The mixture was cooled to 1050°C at a rate of 1°C / min, kept warm for annealing for 1 hour, and then cooled to room temperature with the furnace.
[0052] Comparative Example 1:
[0053] The same as Example 1, except that no sintering aid, i.e., no CuO and Fe 2 O 3 .
[0054] Comparative Example 2:
[0055] The same as Example 1, except that no La was added to prepare 0.95 Sr 0.05 MnO 3 Raw materials, that is, without adding La 2 O 3 、SrCO 3 、MnO 2 .
[0056] Comparative Example 3:
[0057] It is basically the same as Example 1, except that LaMnO 3 The raw materials used to prepare La 0.95 Sr 0.05 MnO 3 The raw material is La 2 O 3 、MnO 2 Replace La 2 O 3 、SrCO 3 、MnO 2 .
[0058] Comparative Example 4:
[0059] It is basically the same as Example 1, except that after the heat preservation sintering, the material is cooled to room temperature in the furnace without annealing.
[0060] Performance Test:
[0061] The surfaces of the electronic ceramic samples prepared in Examples 1-5 and Comparative Examples 1-4 were polished, coated with silver paste on both sides, kept at 750°C for 10 min, and finally polarized at a DC voltage of 4 kV / mm for 20 min in silicone oil at 120°C. After polarization, they were placed for 24 hours as samples to test their electrical properties.
[0062] The room temperature piezoelectric constant of the sample was measured using a ZJ-3AN quasi-static piezoelectric constant tester (ZJ-3A);
[0063] A precision impedance analyzer (Agilent HP4294A) was used to analyze the electromechanical coupling coefficient kp and mechanical quality factor Qm of the sample;
[0064] Test and calculate the Curie temperature Tc of the sample according to GBT3389.3 "Test Methods for Performance of Piezoelectric Ceramic Materials - Test of Curie Temperature Tc";
[0065] The test results are shown in Table 1 below:
[0066] Table 1:
[0067] ;
[0068] It can be seen from Table 1 above that the barium titanate-based electronic ceramics prepared in the present invention have good piezoelectric properties and a relatively high Curie temperature.
[0069] 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 barium titanate-based electronic ceramic, characterized in that: Its chemical structure is as follows: (1-x)BaTiO3-xLa 1-y A y MnO3-αwt% sintering aid 0.05≤x≤0.25, 0.01≤y≤0.1, 0<α≤10; A is Sr and / or Co; The sintering aid is any one or more combinations of CuO, ZnO and Fe2O3.
2. The barium titanate-based electronic ceramic according to claim 1, characterized in that: The sintering aid is a combination of CuO and Fe2O3; The weight ratio of CuO to Fe2O3 is 1-5:1-5.
3. The barium titanate-based electronic ceramic according to claim 1, characterized in that: A is Sr.
4. The barium titanate-based electronic ceramic according to claim 1, wherein: 0.1≤x≤0.2, 0.04≤y≤0.06, 1≤α≤3.
5. The barium titanate-based electronic ceramic according to claim 1, characterized in that: x=0.15,y=0.05,α=2.
6. A method for preparing a barium titanate-based electronic ceramic according to any one of claims 1 to 5, characterized in that: BaCO3, TiO2, La2O3, ACO3, MnO2 and sintering aids are mixed and ball-milled, dried, pre-sintered, granulated with binder, sieved and pressed to obtain a green body. The green body is heated to 600-650℃, kept warm for 1-3h to debind, then continued to heat to 1350-1450℃ and sintered for 2-4h, cooled to 1000-1050℃, annealed for 1-3h, and then cooled to room temperature with the furnace.
7. The method for preparing barium titanate-based electronic ceramics according to claim 6, characterized in that: The pre-firing temperature is 900-950°C and the pre-firing time is 1-3h.
8. The method for preparing barium titanate-based electronic ceramics according to claim 6, characterized in that: The binder is a polyvinyl alcohol solution or a polyvinyl butyral solution.
9. The method for preparing barium titanate-based electronic ceramics according to claim 6, characterized in that: The heating rate during sintering is 10-30°C / min, and the cooling rate is 1-5°C / min.