High-expansion microwave dielectric ceramic material as well as preparation method and application thereof

Abstract

The invention relates to a high-expansion microwave dielectric ceramic material as well as a preparation method and application thereof. The high-expansion microwave dielectric ceramic material is prepared from the following chemical components in percentage by mole: 0 to 2.61 mol percent of SrO, 38.41 to 48.66 mol percent of CaO, 2.6 to 37.88 mol percent of TiO2, 0.86 to 22.55 mol percent of Sm2O3, 10.73 to 23.27 mol percent of Al2O3, 1.5 to 10.67 mol percent of La2O3, 0.22 to 0.31 mol percent of MnO2 and 0.73 to 1.01 mol percent of Nb2O5, wherein the total mol percent of the SrO, the CaO, the TiO2, the Sm2O3, the Al2O3, the La2O3, the MnO2 and the Nb2O5 is 100 percent.

Description

Technical Field

[0001] This invention belongs to the field of ceramic material preparation technology, specifically relating to a high-expansion microwave dielectric ceramic material, its preparation method, and its application. Background Technology

[0002] With the development of microwave technology, higher demands are being placed on the miniaturization, high performance, and multifunctionality of microwave radio frequency (RF) devices. Composite matching and integration of different devices and modules has become an important direction for the development of microwave device technology. Microwave dielectric ceramic materials are crucial core materials for microwave RF components, widely used in dielectric resonators, dielectric substrates, RF antennas, and other microwave devices, characterized by their versatility in material systems and excellent performance. To achieve high integration of modules and high reliability requirements under harsh operating environments, the basic material systems used in each device must possess good mechanical matching characteristics to reduce serious problems such as device failure and performance degradation caused by material mechanical mismatch during device fabrication and use.

[0003] In the design of novel nested microstrip circulators, it is necessary to integrate two different types of functional materials, microwave dielectric ceramic materials and ferrite materials, through nested composite integration. Ferrite materials typically have a high coefficient of thermal expansion (generally α). 30-500℃ The coefficient of thermal expansion is 10.6-11.5 ppm / ℃, while traditional dielectric ceramic materials have a lower coefficient of thermal expansion, making it difficult to solve the problems of material cracking and device failure caused by material mechanical mismatch during high-temperature nested sealing integration of these two types of materials. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a high-expansion microwave dielectric ceramic material that can be integrated with ferrite materials, solving the problem of mechanical matching between dielectric ceramic materials and ferrite materials, and meeting the application requirements of dielectric-ferrite heterogeneous integrated composite substrate materials for novel nested composite structure microstrip ring / isolation devices.

[0005] In a first aspect, the present invention provides a high-expansion microwave dielectric ceramic material, the chemical composition of which comprises, based on a total molar percentage of 100%, SrO: 0–2.61 mol%, CaO: 38.41–48.66 mol%, TiO2: 2.6–37.88 mol%, Sm2O3: 0.86–22.55 mol%, Al2O3: 10.73–23.27 mol%, La2O3: 1.5–10.67 mol%, MnO2: 0.22–0.31 mol%, and Nb2O5: 0.73–1.01 mol%.

[0006] Preferably, the dielectric constant of the high-expansion microwave dielectric ceramic material is 18.5 to 46, the quality factor Qf is 45000 to 76000 GHz, and the coefficient of thermal expansion CTE (30 to 500 °C) is 10.8 to 11.3 ppm / °C.

[0007] Secondly, the present invention provides a method for preparing the above-mentioned high-expansion microwave dielectric ceramic material, the method comprising the following steps: (1) Weigh the SrO source, CaO source, TiO2, Sm2O3, Al2O3 and La2O3 raw material powders according to the element stoichiometry in the chemical composition of the high expansion microwave dielectric ceramic material, mix them and calcine them to obtain the calcined synthetic material; (2) Weigh the calcined composite material, MnO2, and Nb2O5 according to the element stoichiometry in the chemical composition of the high expansion microwave dielectric ceramic material, mix and granulate to obtain the high expansion microwave dielectric ceramic material powder; (3) The high-expansion microwave dielectric ceramic material powder is shaped and sintered to obtain the high-expansion microwave dielectric ceramic material.

[0008] Preferably, in step (1), the SrO source is SrCO3 and the CaO source is CaCO3.

[0009] Preferably, in step (1), the process of mixing the raw material powder is as follows: ball milling in a ball mill jar containing zirconia balls for 2 to 4 hours, the ball milling medium is deionized water, added at a ratio of material:water = 1:2, and the mixed slurry is placed in a drying oven to dry after ball milling.

[0010] Preferably, in step (1), the calcination synthesis is carried out in a muffle furnace at a calcination temperature of 1250-1330°C for 4-8 hours.

[0011] Preferably, in step (2): the calcined synthetic material, MnO2, and Nb2O5 are mixed in a ball mill jar containing zirconia balls, and a binder and deionized water are added; the granulation method is spray granulation.

[0012] Preferably, in step (3), the sintering is carried out in a muffle furnace at a temperature of 1430–1550°C for 4–6 hours.

[0013] Thirdly, the present invention provides an application of the above-mentioned high-expansion microwave dielectric ceramic material in the preparation of dielectric-ferrite heterogeneous integrated composite substrate material for novel nested composite structure microstrip ring or isolation devices.

[0014] Beneficial effects (1) The matching dielectric ceramic material prepared by the present invention has both excellent microwave dielectric properties and high thermal expansion coefficient, which can be well thermodynamically matched and integrated with ferrite materials, meeting the application requirements of heterogeneous integrated composite materials such as novel nested microstrip ring / isolation devices. (2) The material production process provided by the present invention is simple and feasible, suitable for mass industrial production, and has extremely high economic practicality. Attached Figure Description

[0015] Figure 1 The graph shows the thermal expansion performance data of the high-expansion microwave dielectric ceramic materials prepared in Examples 1 and 2. Detailed Implementation

[0016] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0017] First, this invention provides a high-expansion microwave dielectric ceramic material. The chemical composition of this high-expansion microwave dielectric ceramic material may include, based on a total molar percentage of 100%, SrO: 0–2.61 mol%, CaO: 38.41–48.66 mol%, TiO2: 2.6–37.88 mol%, Sm2O3: 0.86–22.55 mol%, Al2O3: 10.73–23.27 mol%, La2O3: 1.5–10.67 mol%, MnO2: 0.22–0.31 mol%, and Nb2O5: 0.73–1.01 mol%.

[0018] By limiting the content of the aforementioned components, this invention enables the high-expansion microwave dielectric ceramic material to possess both excellent microwave dielectric properties and good thermodynamic matching with ferrite materials. This invention employs a high-Ca, high-Al composition design, and through rational control of the relative proportions of each component, utilizes a solid-phase synthesis method (described later) to form a substitutional solid solution. Large ionic radii such as Sm and La ions are used to increase the degree of phase structure distortion and non-harmonic displacement of the material, thereby improving the material's thermal expansion properties while maintaining its excellent microwave dielectric properties.

[0019] The microwave dielectric and thermodynamic properties of the high-expansion microwave dielectric ceramic material were tested. The diameter and thickness of the samples were measured using a micrometer and an Agilent E8362APNA network analyzer. The dielectric properties of the prepared cylindrical ceramic material were measured using the open-cavity method, with a test frequency range of 8–14 GHz. Thermal expansion properties were tested using a NETZSCH DIL402C dilatometer, with a test temperature range of 30–500 °C.

[0020] In some embodiments, the dielectric constant of the high-expansion microwave dielectric ceramic material can be in the range of 18.5 to 46, the quality factor Qf can be in the range of 45000 to 76000 GHz, and the coefficient of thermal expansion CTE (30 to 500 °C) can be in the range of 10.8 to 11.3 ppm / °C.

[0021] The following is an exemplary description of a method for preparing the high-expansion microwave dielectric ceramic material provided by the present invention. The preparation method may include the following steps: (1) Weigh the SrO source, CaO source, TiO2, Sm2O3, Al2O3 and La2O3 raw material powders according to the element stoichiometry in the chemical composition of the high expansion microwave dielectric ceramic material, mix them and calcine them to obtain the calcined synthetic material; (2) Weigh the calcined composite material, MnO2, and Nb2O5 according to the element stoichiometry in the chemical composition of the high expansion microwave dielectric ceramic material, mix and granulate to obtain the high expansion microwave dielectric ceramic material powder; (3) The high-expansion microwave dielectric ceramic material powder is shaped and sintered to obtain the high-expansion microwave dielectric ceramic material.

[0022] In some implementations, in step (1), the SrO source can be SrCO3 and the CaO source can be CaCO3.

[0023] In some embodiments, in step (1), the process of mixing the raw material powder can be as follows: ball milling in a ball mill jar containing zirconia balls for 2 to 4 hours, the ball milling medium being deionized water, added at a ratio of material:water = 1:2, and the mixed slurry placed in a drying oven to dry after ball milling.

[0024] In some embodiments, in step (1), the calcination synthesis can be carried out in a muffle furnace, the calcination temperature can be 1250-1330°C, and the calcination synthesis time can be 4-8 hours.

[0025] In some embodiments, in step (2), the calcination of the synthetic material, the mixing of MnO2 and Nb2O5 can be carried out in a ball mill jar containing zirconia balls, and a binder and deionized water are added; the granulation method can be spray granulation.

[0026] In some embodiments, in step (3), the sintering can be carried out in a muffle furnace, the sintering temperature can be 1430-1550°C, and the sintering time can be 4-6 hours.

[0027] This invention employs a pre-synthesis, re-granulation, and sintering process. By pre-synthesizing all components except MnO2 and Nb2O5, and then adding MnO2 and Nb2O5 for sintering, this process avoids premature entry of Mn and Nb ions into the crystal lattice, preventing the formation of high-dielectric-loss impurity phases and ensuring high microwave dielectric properties of the material. During sintering, this process utilizes the role of MnO2 in preventing Ti ion reduction and Nb ions in refining the crystal structure, promoting ceramic densification and improving the material's microwave dielectric properties and mechanical strength.

[0028] The preparation method provided by this invention adopts a traditional solid-state reaction process, which is simple, feasible, and reproducible. Furthermore, the high-expansion microwave dielectric ceramic material obtained by the preparation method provided by this invention has both excellent microwave dielectric properties and thermodynamic properties.

[0029] The high-expansion microwave dielectric ceramic material provided by this invention can be matched and sealed with various types of ferrite materials such as garnet or spinel, meeting the high reliability application requirements of microstrip ring / isolation devices.

[0030] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0031] Example 1

[0032] The preparation method of the high-expansion microwave dielectric ceramic material (chemical composition: SrO: 2.53 mol%, CaO: 46.35 mol%, TiO2: 6.55 mol%, Sm2O3: 19.51 mol%, Al2O3: 21.27 mol%, La2O3: 2.54 mol%, MnO2: 0.29 mol%, Nb2O5: 0.95 mol%) provided in this embodiment includes the following steps: (1) Weigh the raw material powders SrCO3, CaCO3, TiO2, Sm2O3, Al2O3 and La2O3 according to the element stoichiometry in the chemical composition of the high expansion microwave dielectric ceramic material, put them into a ball mill, add zirconia balls, and add deionized water at a ratio of material:water = 1:2. Ball mill for 4 hours, place the ball-milled slurry in a drying oven to dry, and mix; calcine the uniformly mixed raw material powder in a muffle furnace at 1300℃ for 6 hours to pre-synthesize and obtain the calcined synthetic material; (2) Weigh the calcined synthetic material, MnO2, and Nb2O5 obtained in step (1) according to the element stoichiometry in the chemical composition of the high expansion microwave dielectric ceramic material, put them into the ball mill barrel, add zirconia balls, deionized water and binder, ball mill and then spray granulation to obtain high expansion microwave dielectric ceramic material powder. (3) The high expansion microwave dielectric ceramic material powder obtained in step (2) is molded into a cylindrical blank, and then placed in a muffle furnace and sintered at 1450°C for 5 hours to obtain the high expansion microwave dielectric ceramic material.

[0033] The microwave dielectric properties of the matched dielectric ceramic were obtained by using a network analyzer and the open-cavity resonant method. The thermodynamic properties of the matched ceramic were also tested using thermal expansion analysis to obtain its thermal expansion properties. Specific performance details are summarized in Table 1 below.

[0034] Example 2

[0035] The preparation method of the high-expansion microwave dielectric ceramic material provided in this embodiment is the same as that in Example 1, with the main difference being the adjustment of the proportions and contents of each component and the process parameters. The specific component proportions, process parameters, and material properties are shown in Table 2 below.

[0036] Figure 1 The figures show the thermal expansion properties of the high-expansion microwave dielectric ceramic materials prepared in Examples 1 and 2. As can be seen from the figures, the ceramic materials prepared in this invention have a high coefficient of thermal expansion and exhibit thermodynamic properties comparable to ferrite materials.

[0037] Comparative Example 1

[0038] The preparation method of the high-expansion microwave dielectric ceramic material provided in this comparative example is the same as that in Example 1, the main difference being: the adjustment of the proportions and contents of each component and the process parameters. The specific component proportions, process parameters, and material properties are shown in Table 3 below.

[0039] As can be seen from Table 3, microwave dielectric ceramic materials prepared beyond the system composition ratio required by the technical solution provided by this invention or beyond the process parameter range required by this patent will have their microwave dielectric properties and thermal expansion properties greatly affected, with some indicators deteriorating significantly.

[0040] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A high-expansion microwave dielectric ceramic material, characterized in that, The chemical composition of the high-expansion microwave dielectric ceramic material includes, based on a total mole percentage of 100%, SrO: 0–2.61 mol%, CaO: 38.41–48.66 mol%, TiO2: 2.6–37.88 mol%, Sm2O3: 0.86–22.55 mol%, Al2O3: 10.73–23.27 mol%, La2O3: 1.5–10.67 mol%, MnO2: 0.22–0.31 mol%, and Nb2O5: 0.73–1.01 mol%.

2. The high-expansion microwave dielectric ceramic material according to claim 1, characterized in that, The dielectric constant of the high-expansion microwave dielectric ceramic material is 18.5–46, the quality factor Qf is 45000–76000 GHz, and the coefficient of thermal expansion CTE (30–500 °C) is 10.8–11.3 ppm / °C.

3. A method for preparing the high-expansion microwave dielectric ceramic material according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) Weigh the SrO source, CaO source, TiO2, Sm2O3, Al2O3 and La2O3 raw material powders according to the element stoichiometry in the chemical composition of the high expansion microwave dielectric ceramic material, mix them and calcine them to obtain the calcined synthetic material; (2) Weigh the calcined composite material, MnO2, and Nb2O5 according to the element stoichiometry in the chemical composition of the high expansion microwave dielectric ceramic material, mix and granulate to obtain the high expansion microwave dielectric ceramic material powder; (3) The high-expansion microwave dielectric ceramic material powder is shaped and sintered to obtain the high-expansion microwave dielectric ceramic material.

4. The preparation method according to claim 3, characterized in that, In step (1), the SrO source is SrCO3 and the CaO source is CaCO3.

5. The preparation method according to claim 3 or 4, characterized in that, In step (1), the process of mixing the raw material powder is as follows: ball milling for 2 to 4 hours in a ball mill jar containing zirconia balls, with deionized water as the ball milling medium, added at a ratio of material:water = 1:2, and the mixed slurry placed in a drying oven to dry after ball milling.

6. The preparation method according to any one of claims 3-5, characterized in that, In step (1), the calcination synthesis is carried out in a muffle furnace at a calcination temperature of 1250-1330°C for 4-8 hours.

7. The preparation method according to any one of claims 3-6, characterized in that, In step (2): calcined synthetic material, MnO2, and Nb2O5 are mixed in a ball mill jar containing zirconia balls, and binder and deionized water are added; the granulation method is spray granulation.

8. The preparation method according to any one of claims 3-7, characterized in that, In step (3), the sintering is carried out in a muffle furnace at a temperature of 1430-1550°C for 4-6 hours.

9. The application of the high-expansion microwave dielectric ceramic material according to claim 1 or 2 in the preparation of dielectric-ferrite heterogeneous integrated composite substrate material for novel nested composite structure microstrip ring or isolation devices.

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