Microwave dielectric ceramic material, preparation method and application thereof

Abstract

The application discloses a microwave dielectric ceramic material, a preparation method and application thereof. The microwave dielectric ceramic material comprises a main crystal phase and a doping cation. The chemical formula of the main crystal phase is Mg(Ti2O5) x -Mg(Al2O4) (1‑x) wherein 0.17<=x<=0.26; the doping cation comprises at least one of barium ions, calcium ions, zinc ions, lanthanum ions, niobium ions and bismuth ions; the barium ions and the calcium ions replace magnesium ions in the main crystal phase, and the zinc ions, the lanthanum ions, the niobium ions and the bismuth ions replace magnesium ions, aluminum ions or titanium ions in the main crystal phase; the magnesium ions, the aluminum ions and the titanium ions in the main crystal phase are replaced by the barium ions, the calcium ions, the zinc ions, the lanthanum ions, the niobium ions and the bismuth ions, so that the crystal lattice in the main crystal phase is distorted, the final synthesis temperature is reduced, the dielectric constant and the volume temperature coefficient are adjusted, the dielectric loss is reduced, and the comprehensive performance of the microwave dielectric ceramic material is improved.

Description

Technical Field

[0001] This invention relates to the field of microwave component technology, specifically to a microwave dielectric ceramic material, its preparation method, and its application. Background Technology

[0002] Microwave dielectric ceramics are key materials for microwave components such as resonators, filters, and dielectric ceramic substrates in modern mobile communications, satellite communications, and military radar. With the rapid development of next-generation mobile communications, higher demands are being placed on signal transmission speeds. Compared to traditional materials, low-dielectric-loss microwave dielectric ceramics offer advantages such as low dielectric loss, high operating frequency, and high transmission speed, meeting the needs of microwave devices moving towards higher frequencies, higher speeds, and higher reliability. Their near-zero temperature coefficient is beneficial for system temperature stability.

[0003] Since its development began in 1939, microwave dielectric ceramics have seen rapid advancements in various low, medium, and high dielectric types, resulting in a wide variety of products and increasingly mature and sophisticated systems. For low dielectric constant microwave dielectric ceramics with a dielectric constant εr around 12, the main systems are Al2O3-TiO2 and MgAl2O4-SrTiO3. The former is difficult to prepare with low-loss microwave dielectric ceramics at 15 GHz when the raw material purity is below 99.99%, while high-purity raw materials have higher production costs, leading to higher prices (generally three times the price). The latter requires the separate synthesis of MgAl2O4 and SrTiO3 before composite synthesis, resulting in a relatively complex process, long production cycle, and high sintering temperatures. Summary of the Invention

[0004] The technical problem to be solved by this invention is the aforementioned problem existing in existing low dielectric constant microwave dielectric ceramics. This invention provides a microwave dielectric ceramic material that, by doping with cations, induces lattice distortion in the main crystal phase, thereby reducing the synthesis temperature of the main crystal phase, improving the internal structure of the ceramic body, making the main crystal phase grains compact and orderly arranged, and improving the comprehensive performance of the ceramic material, such as dielectric constant and dielectric loss.

[0005] The primary objective of this invention is to provide a microwave dielectric ceramic material comprising a main crystalline phase and doped cations, wherein the chemical formula of the main crystalline phase is Mg(Ti2O5). x -Mg(Al2O4) (1-x) Where 0.17≤x≤0.26;

[0006] The doped cations include at least one of barium ion, calcium ion, zinc ion, lanthanum ion, niobium ion and bismuth ion;

[0007] Barium and calcium ions replace magnesium ions in the main crystalline phase, while zinc, lanthanum, niobium, and bismuth ions replace magnesium, aluminum, or titanium ions in the main crystalline phase.

[0008] By substituting magnesium, aluminum, and titanium ions in the main crystal phase with barium, calcium, zinc, lanthanum, niobium, and bismuth ions, the crystal lattice in the main crystal phase is distorted, which ultimately reduces the synthesis temperature. It can also adjust the dielectric constant and capacity temperature coefficient, and even reduce dielectric loss.

[0009] As one possible design, the barium and calcium ions are derived from their respective carbonates. During the sintering synthesis stage, carbonate ions generate carbon dioxide and overflow, avoiding any impact on the performance of the microwave dielectric ceramic material. Simultaneously, this creates pores between particles, facilitating airflow and ensuring a uniform synthesis atmosphere, which is beneficial for the formation of the main crystalline phases MgTi₂O₅-MgAl₂O₄.

[0010] As one possible design, the zinc ions, lanthanum ions, niobium ions, and bismuth ions are derived from their respective oxides. This avoids introducing other substances that could affect the properties of the microwave dielectric ceramic material.

[0011] A second objective of this invention is to provide a method for preparing microwave dielectric ceramic materials, comprising:

[0012] The following ingredients are mixed: 34-41 parts by weight of magnesium carbonate, 15-19 parts by weight of titanium dioxide, 30-36 parts by weight of aluminum oxide, 0.6-2.5 parts by weight of barium carbonate and / or calcium carbonate, and 8-14 parts by weight of at least one of zinc oxide, lanthanum oxide, niobium pentoxide and bismuth oxide. The mixture is then ground and mixed for 5-8 hours at a weight ratio of material:ball:water of 1:5-6:1.5-2.5. After drying, the mixture is pre-calcined at 1180-1220℃ for 3-5 hours to obtain calcined block 1.

[0013] After crushing the calcined block 1, it is ground and mixed for 15 to 45 hours according to the weight ratio of material:ball:water of 1:5 to 6:1.5 to 2.5. After drying, it is passed through an 80-mesh sieve to obtain a dry powder. Paraffin wax is added to the dry powder and pressed into round green blanks. The blanks are sintered at 1270℃ to 1320℃ for 2 to 3 hours to obtain the microwave dielectric ceramic material. The amount of paraffin wax added is 8 to 12% of the mass of the dry powder.

[0014] This invention mixes various raw materials together to obtain microwave dielectric ceramic materials. Compared with the existing technology that requires the separate synthesis of MgAl2O4 and SrTiO3, this invention saves steps and shortens the production cycle while ensuring that the microwave dielectric ceramic materials meet the performance requirements. It is worth promoting and using.

[0015] As one possible design, the magnesium carbonate has a purity ≥97%, the titanium dioxide has a purity ≥98%, and the aluminum oxide has an electronic grade purity. Through the preparation method and doped cations disclosed in this invention, raw materials with lower purity can be used while meeting relevant performance requirements, which is beneficial for saving manufacturing costs.

[0016] The preparation process uses domestically produced raw materials, and is free of toxic and harmful substances such as lead and cadmium. It is green and environmentally friendly, and can be mass-produced industrially.

[0017] As one possible design, the drying process temperature is 130–150°C. The main purpose is to evaporate the solvent.

[0018] As one possible design, the microwave dielectric ceramic material has a dielectric constant of 11–14 and a dielectric loss of 0.7 × 10⁻⁶ at 1 MHz. -4 ~2.9×10 -4 It has a capacity temperature coefficient of -30 to 30 ppm / ℃. It has a wide range of applications (operating frequencies up to 15 GHz), stable performance, and can be used to manufacture microwave components such as resonators, filters, dielectric ceramic substrates, and antennas.

[0019] A third objective of this invention is to provide a ceramic substrate, primarily made of microwave dielectric ceramic material or microwave dielectric ceramic material obtained by a preparation method.

[0020] As one possible design, the ceramic substrate has dimensions of 38.1 × 38.1 × 0.17 mm, and at a test frequency of 15 GHz, the dielectric constant of the ceramic substrate is 12.14, and the dielectric loss is 8 × 10⁻⁶. -4 .

[0021] Ceramic substrates made from the microwave dielectric ceramic material disclosed in this invention also have good overall performance and are worth promoting and using. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0023] Figure 1 The XRD pattern of the ceramic material was obtained in Example 10. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0025] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0027] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] Example 1

[0030] This embodiment provides a method for preparing MgTi2O5-MgAl2O4 microwave dielectric ceramic material, including:

[0031] (1) 35.95 parts by weight of magnesium carbonate, 16.89 parts by weight of titanium dioxide, 33.11 parts by weight of aluminum oxide, 3.33 parts by weight of barium carbonate and 10.72 parts by weight of zinc oxide were prepared in the following proportions: magnesium carbonate with a purity of 97.51%, titanium dioxide with a purity of 98.34%, and aluminum oxide with electronic grade. The resulting mixture was ground and mixed for 5 hours with zirconium dioxide balls as the grinding medium and water as the solvent, according to the weight ratio of material:ball:water of 1:5:1.5, to obtain a uniformly mixed slurry. The slurry was dried at 140°C and passed through a 40-mesh sieve. It was then pre-calcined at 1180°C for 3 hours to obtain a primary synthesized calcined block, which was then crushed for later use.

[0032] (2) The sintered material obtained in step (1) is ground a second time. Zirconia balls are used as the grinding medium and water is used as the solvent. The mixture is ground and mixed for 15 hours with a material:ball:water weight ratio of 1:5:1.5. The mixture is then passed through a 320-mesh sieve to obtain a uniformly mixed slurry. The slurry is dried at 140°C and passed through an 80-mesh sieve. The dried powder is then pressed into round green blanks with 8% of its mass of paraffin and sintered at 1270°C for 2 hours to obtain the medium ceramic material.

[0033] Example 2

[0034] (1) 36.56 parts by weight of magnesium carbonate, 15.95 parts by weight of titanium dioxide, 30.3 parts by weight of aluminum oxide, 3.38 parts by weight of calcium carbonate and 13.81 parts by weight of lanthanum oxide were prepared in the following proportions: magnesium carbonate with a purity of 97.51%, titanium dioxide with a purity of 98.34%, and aluminum oxide with electronic grade. The resulting mixture was ground and mixed for 8 hours with zirconium dioxide balls as the grinding medium and water as the solvent, according to the weight ratio of material:ball:water of 1:5.4:2.4, to obtain a uniformly mixed slurry. The slurry was dried at 140°C and passed through a 40-mesh sieve. It was then pre-calcined at 1210°C for 4 hours to obtain a primary synthesized calcined block, which was then crushed for later use.

[0035] (2) The sintered material obtained in step (1) is ground a second time. Zirconia balls are used as the grinding medium and water is used as the solvent. The mixture is ground and mixed for 15 hours according to the weight ratio of material:ball:water of 1:5.3:2.2. The mixture is then passed through a 320-mesh sieve to obtain a uniformly mixed slurry. The slurry is dried at 140°C and passed through an 80-mesh sieve. The dried powder is then pressed into round green blanks with 10% of its mass of paraffin and sintered at 1290°C for 2.5 hours to obtain the medium ceramic material.

[0036] Example 3

[0037] (1) 36.36 parts by weight of magnesium carbonate, 17.08 parts by weight of titanium dioxide, 33.48 parts by weight of aluminum oxide, 2.24 parts by weight of calcium carbonate and 10.84 parts by weight of niobium pentoxide were prepared in the following proportions: magnesium carbonate with a purity of 97.51%, titanium dioxide with a purity of 98.34%, and aluminum oxide with electronic grade. The resulting mixture was ground and mixed for 8 hours with zirconium dioxide balls as the grinding medium and water as the solvent, according to the weight ratio of material:ball:water of 1:5.5:2.1, to obtain a uniformly mixed slurry. The slurry was dried at 140°C and passed through a 40-mesh sieve. It was then pre-calcined at 1210°C for 4 hours to obtain a primary synthesized calcined block, which was then crushed for later use.

[0038] (2) The sintered material obtained in step (1) is ground twice. Zirconia balls are used as the grinding medium and water is used as the solvent. The mixture is ground and mixed for 15 hours with a material:ball:water weight ratio of 1:5.8:1.7. The mixture is then passed through a 320-mesh sieve to obtain a uniformly mixed slurry. The slurry is dried at 140°C and passed through an 80-mesh sieve. The dried powder is then pressed into round green blanks with 12% of its mass of paraffin wax and sintered at 1310°C for 3 hours to obtain the medium ceramic material.

[0039] Example 4

[0040] The difference from Example 1 is that: 36.57 parts magnesium carbonate, 17.18 parts titanium dioxide, 33.67 parts aluminum oxide, 1.69 parts calcium carbonate, and 10.9 parts bismuth oxide.

[0041] Example 5

[0042] The difference from Example 1 is that: 36.54 parts magnesium carbonate, 17.16 parts titanium dioxide, 33.65 parts aluminum oxide, 1.69 parts barium carbonate, 6.09 parts bismuth oxide, and 4.9 parts niobium pentoxide.

[0043] Example 6

[0044] The difference from Example 1 is as follows: 36.63 parts magnesium carbonate, 17.2 parts titanium dioxide, 33.48 parts aluminum oxide, 1.69 parts barium carbonate, 4.02 parts bismuth oxide, 4.9 parts niobium pentoxide, and 2.07 parts lanthanum oxide.

[0045] Example 7

[0046] This embodiment provides a method for preparing MgTi2O5-MgAl2O4 microwave dielectric ceramic material, including:

[0047] (1) 35.95 parts by weight of magnesium carbonate, 16.89 parts by weight of titanium dioxide, 33.11 parts by weight of aluminum oxide, 3.33 parts by weight of barium carbonate and 10.72 parts by weight of zinc oxide were prepared in the following proportions: magnesium carbonate with a purity of 97.51%, titanium dioxide with a purity of 98.34%, and aluminum oxide with electronic grade. The resulting mixture was ground and mixed for 8 hours with zirconium dioxide balls as the grinding medium and water as the solvent, according to the weight ratio of material:ball:water of 1:6:2.5, to obtain a uniformly mixed slurry. The slurry was dried at 140°C and passed through a 40-mesh sieve. It was then pre-calcined at 1220°C for 5 hours to obtain a primary synthesized calcined block, which was then crushed for later use.

[0048] (2) The sintered material obtained in step (1) is ground a second time. Zirconia balls are used as the grinding medium and water is used as the solvent. The mixture is ground and mixed for 35 hours according to the weight ratio of material:ball:water of 1:6:2.5. The mixture is passed through a 320-mesh sieve to obtain a uniformly mixed slurry. The slurry is dried at 140°C and passed through an 80-mesh sieve. The dried powder is then pressed into round green blanks with 12% of its mass of paraffin and sintered at 1320°C for 3 hours to obtain the medium ceramic material.

[0049] Example 8

[0050] This embodiment provides a method for preparing MgTi2O5-MgAl2O4 microwave dielectric ceramic material, including:

[0051] (1) 35.95 parts by weight of magnesium carbonate, 16.89 parts by weight of titanium dioxide, 33.11 parts by weight of aluminum oxide, 3.33 parts by weight of barium carbonate and 10.72 parts by weight of zinc oxide were prepared in the following proportions: magnesium carbonate with a purity of 97.51%, titanium dioxide with a purity of 98.34%, and aluminum oxide with electronic grade. The resulting mixture was ground and mixed for 7 hours with zirconium dioxide balls as the grinding medium and water as the solvent, according to the weight ratio of material:ball:water of 1:5.4:2.0, to obtain a uniformly mixed slurry. The slurry was dried at 140°C and passed through a 40-mesh sieve. It was then pre-calcined at 1200°C for 4.2 hours to obtain a primary synthesized calcined block, which was then crushed for later use.

[0052] (2) The sintered material obtained in step (1) is ground a second time. Zirconia balls are used as the grinding medium and water is used as the solvent. The mixture is ground and mixed for 45 hours according to the weight ratio of material:ball:water of 1:5.3:2.04. The mixture is passed through a 320-mesh sieve to obtain a uniformly mixed slurry. The slurry is dried at 140°C and passed through an 80-mesh sieve. The dried powder is then pressed into round green blanks with 9.7% of its mass of paraffin and sintered at 1290°C for 2.5 hours to obtain the medium ceramic material.

[0053] Example 9

[0054] The difference from Example 1 is that: 39.13g magnesium carbonate, 16.71g titanium dioxide, 32.76g aluminum oxide, 0.73g calcium carbonate, 6.34g zinc oxide, and 4.33g niobium pentoxide are added in the specified proportions.

[0055] Example 10

[0056] The difference from Example 1 is that: 36.51 parts magnesium carbonate, 17.15 parts titanium dioxide, 33.63 parts aluminum oxide, 1.69 parts barium carbonate, and 11.02 parts lanthanum oxide.

[0057] Comparative Example 1

[0058] The difference from Example 1 is that: 35.95 parts magnesium carbonate, 16.89 parts titanium dioxide, 33.11 parts aluminum oxide, and 3.33 parts barium carbonate.

[0059] Comparative Example 2

[0060] The difference from Example 1 is that: 35.95 parts magnesium carbonate, 16.89 parts titanium dioxide, 33.11 parts aluminum oxide, and 10.72 parts zinc oxide.

[0061] Comparative Example 3

[0062] The difference from Example 1 is that: 35.95 parts magnesium carbonate, 16.89 parts titanium dioxide, and 33.11 parts aluminum oxide.

[0063] The performance parameters of the ceramic materials obtained in Examples 1-10 and Comparative Examples 1-3 are shown in Table 1.

[0064] Table 1

[0065]

[0066]

[0067] As shown in Table 1, the microwave dielectric ceramic materials obtained in Examples 1-10 have better performance than those in Comparative Examples 1-3. The dielectric constant (1MHz) of the microwave dielectric ceramic materials obtained in Examples 1-10 is approximately 13, and the dielectric loss (1MHz) is 0.7 × 10⁻⁶. -4 ~2.9×10 -4 The capacitance temperature coefficient is 0±30ppm / ℃. This indicates that microwave dielectric ceramic materials exhibit stable performance and can be used to manufacture microwave components such as resonators, filters, dielectric ceramic substrates, and antennas.

[0068] XRD was performed on the microwave dielectric ceramic material obtained in Example 10, and the results are as follows: Figure 1 As shown, by Figure 1It can be seen that the main components of the microwave dielectric ceramic material obtained in Example 10 are MgTi2O5 and MgAl2O4, and it also contains other peaks.

[0069] The microwave dielectric ceramic material obtained in Example 10 was used to fabricate a ceramic substrate with dimensions of 38.1 × 38.1 × 0.17 mm. At a test frequency of 15 GHz, its dielectric constant was 12.14 and its dielectric loss was 8 × 10⁻⁶. -4 .

[0070] In summary, the microwave dielectric ceramic material obtained by this invention exhibits excellent performance. When fabricated into ceramic substrates, these substrates have a wide range of applications (usable at frequencies up to 15 GHz), demonstrating low dielectric loss even at 15 GHz.

[0071] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A microwave dielectric ceramic material, characterized in that, It includes a main crystalline phase and doped cations, wherein the chemical formula of the main crystalline phase is Mg(Ti2O5). x -Mg(Al2O4) (1-x) Where 0.17≤x≤0.26; The doped cations include at least one of barium ion, calcium ion, zinc ion, lanthanum ion, niobium ion and bismuth ion; Barium and calcium ions replace magnesium ions in the main crystal phase, while zinc, lanthanum, niobium, and bismuth ions replace magnesium, aluminum, or titanium ions in the main crystal phase. This dielectric ceramic material is prepared from the following raw materials in parts by weight: 34–41 parts magnesium carbonate, 15–19 parts titanium dioxide, 30–36 parts aluminum oxide, 0.6–2.5 parts barium carbonate and / or calcium carbonate, 8–14 parts zinc oxide, lanthanum oxide, niobium pentoxide and at least one of the following:

2. The microwave dielectric ceramic material according to claim 1, characterized in that, The barium and calcium ions are derived from their respective carbonates.

3. The microwave dielectric ceramic material according to claim 1, characterized in that, The zinc ions, lanthanum ions, niobium ions, and bismuth ions are derived from their respective oxides.

4. A method for preparing the microwave dielectric ceramic material according to any one of claims 1-3, characterized in that, The preparation method includes: The following ingredients are mixed: 34-41 parts by weight of magnesium carbonate, 15-19 parts by weight of titanium dioxide, 30-36 parts by weight of aluminum oxide, 0.6-2.5 parts by weight of barium carbonate and / or calcium carbonate, and 8-14 parts by weight of at least one of zinc oxide, lanthanum oxide, niobium pentoxide and bismuth oxide. The mixture is then ground and mixed for 5-8 hours at a weight ratio of material:ball:water of 1:5-6:1.5-2.

5. After drying, the mixture is pre-calcined at 1180-1220℃ for 3-5 hours to obtain calcined block 1. After crushing the calcined block 1, it is ground and mixed for 15 to 45 hours according to the weight ratio of material:ball:water of 1:5 to 6:1.5 to 2.

5. After drying, it is passed through an 80-mesh sieve to obtain a dry powder. Paraffin wax is added to the dry powder and pressed into round green blanks. The blanks are sintered at 1270℃ to 1320℃ for 2 to 3 hours to obtain the microwave dielectric ceramic material. The amount of paraffin wax added is 8 to 12% of the mass of the dry powder.

5. The preparation method according to claim 4, characterized in that, The purity of the magnesium carbonate is ≥97%, the purity of the titanium dioxide is ≥98%, and the purity of the aluminum oxide is electronic grade.

6. The preparation method according to claim 4, characterized in that, The drying process temperature is 130~150℃.

7. The preparation method according to claim 4, characterized in that, The microwave dielectric ceramic material has a dielectric constant of 11~14 at 1MHz and a dielectric loss of 0.7×10⁻⁶. -4 ~2.9×10 -4 The capacity temperature coefficient is -30~30ppm / ℃.

8. A ceramic substrate, characterized in that, It is mainly made of microwave dielectric ceramic material as described in any one of claims 1-3 or microwave dielectric ceramic material obtained by the preparation method described in any one of claims 4-7.

9. The ceramic substrate according to claim 8, characterized in that, The ceramic substrate measures 38.1 × 38.1 × 0.17 mm. At a test frequency of 15 GHz, the ceramic substrate exhibits a dielectric constant of 12.14 and a dielectric loss of 8 × 10⁻⁶. -4 .

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