A silicon-based microwave dielectric ceramic temperature-frequency characteristic regulator

Abstract

The application belongs to the technical field of microwave dielectric ceramics, and discloses a silicon-based microwave dielectric ceramic temperature-frequency characteristic regulator, specifically provides an application of a microwave dielectric ceramic material as a microwave dielectric ceramic temperature-frequency characteristic regulator, the chemical formula of the microwave dielectric ceramic material is (Ba x Sr y Ca z )3MgSi2O8, wherein 0 < x < 1, 0 ≤ y < 1, 0 ≤ z < 1, and x + y + z = 1; when z = 0, 0.25 ≤ x ≤ 0.75, 0.25 ≤ y ≤ 0.75; when z ≠ 0, 0.33 ≤ x ≤ 0.34, 0 ≤ y ≤ 0.66. The (Ba x Sr y Ca z )3MgSi2O8 material obtained by improving the composition of the material has the characteristics of low dielectric constant, low dielectric loss and adjustable resonant frequency temperature coefficient, and can be used as a microwave dielectric ceramic temperature-frequency characteristic regulator.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microwave dielectric ceramics, and more particularly relates to a silicon-based microwave dielectric ceramic temperature-frequency characteristic regulator. BACKGROUND

[0002] With the development of 5G technology and mobile communication technology represented by millimeter wave communication technology, the microwave dielectric performance requirements of dielectric materials are getting higher and higher, that is, it is actually required to have a low relative dielectric constant (ε r ) to improve the information transmission rate of the device, a low high-frequency dielectric loss (tanδ) to enhance its frequency selection and reduce energy consumption, and a near-zero resonance frequency temperature coefficient (τ f ) to ensure the stability of the resonance frequency and signal transmission. Silicon-based microwave dielectric ceramics are a research hotspot in the field of microwave dielectric ceramics due to their low dielectric constant, low dielectric loss, low raw material price, environmental protection, and simple process. However, the τ f of silicon-based microwave dielectric ceramics is generally negative, and in actual use, the τ f needs to be adjusted to near zero (|τ f |≤10ppm / ℃) for actual use. Traditional regulators are generally Ti-based regulators, which are prone to react with the matrix material to form a second phase and produce Ti 4+ ions in a reducing atmosphere, thereby causing the medium to fail, and the regulator often has a high dielectric constant, which can significantly increase the ε r of the matrix material after compounding.

[0003] Potassium nitrate type structure silicate compounds A3MgSi2O8 (A = Ba, Sr) have low cost, good luminescent performance and excellent microwave dielectric performance and have attracted widespread attention. Zhou et al. (Yinghan He, Xiaoli Wei, Guoqiang He, et al. Sintering behavior, phase composition, microstructure, and dielectric properties of low-permittivity alkaline earth silicate Sr3MgSi2O8 ceramics [J]. Journal of Materials Science: Materials in Electronics, 2022, 33(35): 26263-26275) found that Sr3MgSi2O8 showed excellent microwave dielectric properties after sintering at 1450℃, ε r = 11.06, Qf = 25,375GHz, τ f= -57.41ppm / ℃. However, in current research, the τ of this material... f All values ​​are large negative values, indicating poor frequency and temperature stability, which cannot meet the needs of practical use. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a silicon-based microwave dielectric ceramic temperature and frequency characteristic modulator, wherein by improving the composition of the material, a (Ba) x Sr y Ca z The 3MgSi2O8 material (where 0 < x < 1, 0 ≤ y < 1, 0 ≤ z < 1, and x + y + z = 1; and when z = 0, 0.25 ≤ x ≤ 0.75, 0.25 ≤ y ≤ 0.75; when z ≠ 0, 0.33 ≤ x ≤ 0.34, 0 ≤ y ≤ 0.66) has the characteristics of low dielectric constant, low dielectric loss, and adjustable temperature coefficient of resonant frequency, and is especially suitable as a temperature and frequency characteristic regulator for microwave dielectric ceramics. This invention can effectively replace current Ti-based regulators and improve the technical problems of Ti-based regulators easily reacting with the matrix, causing an increase in the dielectric constant of the matrix, and making it difficult to meet the sintering requirements under a reducing atmosphere. The resulting (Ba x Sr y Ca z 3MgSi2O8 material is a novel type of silicon-based microwave dielectric ceramic temperature and frequency characteristic regulator. It can adjust the overall resonant frequency temperature coefficient of the ceramic system by adding it (for example, it can make the overall ceramic system achieve a near-zero resonant frequency temperature coefficient). Of course, this microwave dielectric ceramic temperature and frequency characteristic regulator can also be used independently as a microwave dielectric ceramic material. It has a strong regulating effect and has great value in industry.

[0005] To achieve the above objectives, according to one aspect of the present invention, an application of a microwave dielectric ceramic material as a temperature-frequency characteristic modulator of microwave dielectric ceramics is provided, characterized in that the chemical formula of the microwave dielectric ceramic material is (Ba x Sr y Ca z 3MgSi2O8, where 0 < x < 1, 0 ≤ y < 1, 0 ≤ z < 1, and x + y + z = 1; and when z = 0, 0.25 ≤ x ≤ 0.75, 0.25 ≤ y ≤ 0.75; when z ≠ 0, 0.33 ≤ x ≤ 0.34, 0 ≤ y ≤ 0.66;

[0006] This microwave dielectric ceramic material can be added to adjust the overall resonant frequency temperature coefficient of the ceramic system.

[0007] As a further preferred embodiment of the present invention, (Ba x Sr y Caz )3MgSi2O8, 0.25≤x≤0.75, 0.25≤y≤0.75 and z=0.

[0008] As a further preferred embodiment of the present application, the microwave dielectric ceramic material is sintered in air or reducing atmosphere.

[0009] According to another aspect of the present application, the present application provides a microwave dielectric ceramic material as a microwave dielectric material, characterized in that the microwave dielectric ceramic material has a chemical formula of (Ba x Sr y Ca z )3MgSi2O8, wherein 0

[0010] The microwave dielectric ceramic material has a relative dielectric constant ε r ∈ [13.67, 15.80], a quality factor Qf ∈ [10938, 24862] GHz, and a resonance frequency temperature coefficient τ f ∈ [8, 235] ppm / ℃.

[0011] As a further preferred embodiment of the present application, (Ba x Sr y Ca z )3MgSi2O8, x, y and z are located in the interval [0.33, 0.34]; correspondingly, the microwave dielectric ceramic material has a relative dielectric constant ε r ∈ [15.64, 15.80], a quality factor Qf ∈ [10938, 15998] GHz, and a resonance frequency temperature coefficient τ f ∈ [8, 10] ppm / ℃.

[0012] According to still another aspect of the present application, the present application provides a microwave dielectric ceramic material, characterized in that the microwave dielectric ceramic material has a chemical formula of (Ba x Sr y Ca z )3MgSi2O8, wherein 0

[0013] The microwave dielectric ceramic material has a relative dielectric constant ε r∈[13.67, 15.80], the quality factor Qf ∈ [10938, 24862] GHz, the resonance frequency temperature coefficient τ f ∈[8, 235] ppm / ℃.

[0014] As a further preferred embodiment of the present application, (Ba x Sr y Ca z )3MgSi2O8, x, y, z are located in the interval [0.33, 0.34]; accordingly, the relative dielectric constant ε r ∈[15.64, 15.80], the quality factor Qf ∈ [10938, 15998] GHz, the resonance frequency temperature coefficient τ f ∈[8, 10] ppm / ℃.

[0015] By the above technical scheme conceived by the present application, compared with the prior art, the following advantages can be achieved

[0016] Advantages:

[0017] (1) The microwave dielectric ceramic material (Ba x Sr y Ca z )3MgSi2O8 in the present application (wherein 0 < x < 1, 0 ≤ y < 1, 0 ≤ z < 1, and x + y + z = 1; and when z = 0, 0.25 ≤ x ≤ 0.75, 0.25 ≤ y ≤ 0.75; when z ≠ 0, 0.33 ≤ x ≤ 0.34, 0 ≤ y ≤ 0.66) has the advantages of low dielectric constant, low dielectric loss, adjustable resonance frequency temperature coefficient, etc.; it can be used as a microwave dielectric ceramic alone, or as a microwave dielectric ceramic temperature-frequency characteristic adjuster.

[0018] (2) The present application first reports a new type of microwave dielectric ceramic temperature-frequency characteristic adjuster (Ba x Sr y Ca z )3MgSi2O8, by ion substitution and structure control, the resonance frequency temperature coefficient thereof can be adjusted between 8-235 ppm / ℃. For example, by introducing the above adjuster, the resonance frequency temperature coefficient of most microwave dielectric ceramics can be adjusted to near zero (generally, τ f values in the interval [-15, 15] can be considered as near zero, and the smaller the absolute value of τ f is, the better), and the components of the adjuster can be reasonably designed according to actual needs. Based on the present application, (Ba x Sr y Ca z)3MgSi2O8 microwave dielectric ceramic temperature-frequency characteristic adjuster, at this time, the temperature coefficient of the resonant frequency of the material τ f No less than 60 ppm / ℃, when used as an adjuster, it can greatly adjust the temperature stability of the medium material, and achieve better adjustment effect (for example, when the proportion of the adjuster added remains fixed, the greater the temperature coefficient of the resonant frequency of the adjuster itself τ f The overall resonant frequency temperature coefficient τ f of the adjusted material is greater, and the adjustment effect is better).

[0019] The inventor of the present application obtained an anti-reduction microwave dielectric ceramic temperature-frequency characteristic adjuster (see Chinese Patent Application CN202311283653.0) in the early stage of research and development, which satisfies the chemical formula (AO)3(BO)(XO2)2, wherein B=Mn h Mg k , and 0.6≤h≤1 (that is, the B site must have Mn elements). When the component of the material is not substituted, the body is a temperature-frequency characteristic regulator with excellent performance. The present application focuses on the A site element, and the A site element is adjusted by component design (that is, A=Ba x Sr y Ca z , wherein 0 x Sr y Ca z )3MgSi2O8, the present application greatly expands the types of microwave dielectric ceramic temperature-frequency characteristic adjusters and the corresponding material design methods.

[0020] (3) The new microwave dielectric ceramic temperature-frequency characteristic adjuster provided by the present application is easy to obtain, does not contain variable valence elements, has stable process, and can meet sintering under various atmospheres. At the same time, the dielectric constant is low, the dielectric loss is low, and it has obvious advantages over traditional adjusters, and can be widely applied in the fields of filter dielectric materials, LTCC, BME-MLCC (base metal internal electrode ceramic capacitor), etc. Taking the BME-MLCC application as an example, BME-MLCC must be sintered in a reducing atmosphere, so the medium material must have good microwave dielectric properties after sintering in a reducing atmosphere (as detailed in Chinese Patent Application CN202311283653.0). As shown in Examples 3 and 8 below, both of them are prepared (Ba 0.5 Sr 0.5)3MgSi2O8 material, the sintering atmosphere used in Example 3 is air, the sintering atmosphere used in Example 8 is a reducing atmosphere, but the performance ε r , Qf, τ f of both have no obvious attenuation (some parameters are even better). The same is true for Example 7 and Example 9.

[0021] (4) The (Ba x Sr y Ca z )3MgSi2O8 in the present application can also be applied as a microwave dielectric material, expanding the types of microwave dielectric materials. The values of x, y, z can be especially located in the interval [0.33, 0.34] (for example, x = y = z), at this time, the temperature coefficient of the resonant frequency τ f of the material is very close to 0, and can be directly applied as a temperature-stable microwave dielectric material.

[0022] In summary, the present application proposes a new type of silicon-based microwave dielectric ceramic, which has adjustable τ f , and can be especially used as a new type of microwave dielectric ceramic and as a microwave dielectric ceramic temperature-frequency characteristic regulator in combination with a second phase. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the X-ray diffraction (XRD) pattern of the microwave dielectric ceramic material prepared in Examples 1-9 of the present application.

[0024] Figure 2 is the X-ray diffraction pattern of the microwave dielectric ceramic material prepared in Comparative Examples 1-5.

[0025] Figure 3 is the X-ray diffraction pattern of the microwave dielectric ceramic material prepared in Comparative Example 6.

[0026] Figure 4 is the X-ray diffraction pattern of the microwave dielectric ceramic material prepared in Comparative Example 7. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0028] In general, the microwave dielectric ceramic material in the present application (which can also be used as a microwave dielectric ceramic temperature-frequency characteristic regulator; for example, in combination with a second phase, thereby adjusting the overall temperature-frequency characteristics) has the chemical formula (Ba xSr y Ca z )3MgSi2O8, 0 < x < 1, 0≤y<1, 0≤z<1, and x+y+z=1; and, when z=0, 0.25≤x≤0.75, 0.25≤y≤0.75; when z≠0, 0.33≤x≤0.34, 0≤y≤0.66. The preparation method can include the following steps:

[0029] (1) The nominal stoichiometric ratio of Ba element, Sr element, Ca element, Mg element, Si element in the chemical formula (Ba x Sr y Ca z )3MgSi2O8is matched with Ba source material (such as BaCO3, Ba(NO3)2, BaO), Sr source material (such as SrCO3, Sr(NO3)2, SrO), Ca source material (such as CaCO3, CaO), Mg source material (such as MgO, basic magnesium carbonate), and Si source material (such as SiO2, H2SiO3) by using a planetary ball mill in medium water or ethanol for 5-8 h, and then drying at 100-120°C to obtain a mixture;

[0030] (2) The mixture is pre-fired at 1200-1300°C for 2-4 h in air (the heating rate can be, for example, 5°C / min), and the target crystal phase is synthesized. The synthesized pre-fired product is ground in medium water or ethanol for 9-12 h, dried in an oven at 80-120°C, and then added with 4-8 wt% of a binder (for example, 5-7 wt% of a PVA aqueous solution, with 4-8 wt% of PVA as the solute of the pre-fired product) to granulate, and then passed through a 40-mesh standard sieve to obtain a granulated powder.

[0031] (3) The powder is placed in a 12-mm-diameter mold to obtain a green body under a pressure of 100 MPa. The green body is degreased at 550°C for 1 h, and then sintered at 1350-1550°C for 3-6 h in air or a reducing atmosphere (5% H2-N2, i.e., a hydrogen-nitrogen mixed gas with a hydrogen volume percentage of 5%), with a heating rate of 5°C / min.

[0032] Examples 1-9 and Comparative Examples 1-7 are prepared according to the above preparation method, and the differences in the details are shown in Table 1.

[0033] Table 1 Details of components and preparation process conditions of Examples 1-9 and Comparative Examples 1-7

[0034]

[0035]

[0036] The microwave dielectric properties of the samples obtained from Examples 1-9 and Comparative Examples 1-7 were detected, and the results are shown in Table 2. The columnar samples were prepared according to the above steps (1), (2) and (3), and the relative dielectric constant, quality factor and temperature coefficient of resonant frequency of the samples were tested and calculated by using a network analyzer at a test frequency of 8-15 GHz.

[0037] Table 2 Microwave dielectric properties of Examples 1-9 and Comparative Examples 1-3

[0038]

[0039]

[0040] As shown in Table 2, the three performance parameters of the (Ba x Sr y Ca z )3MgSi2O8 ceramic can be flexibly adjusted according to actual needs by adjusting x, y and z. The samples obtained from Examples 1-9 all exhibit positive τ f values. Examples 7 and 9 exhibit relatively low dielectric constant, high quality factor and relatively close to zero τ f value (generally, a τ f value in the interval of [-15, 15] can be considered as close to zero, and the smaller the absolute value of τ f value is, the better it is), which can be used as dielectric materials in fields such as filters, LTCC, BME-MLCC and the like which have relatively high requirements for temperature stability. Examples 1-6 and 8 exhibit relatively large positive τ f values, and if they are compounded with microwave dielectric materials with negative τ f values as temperature-frequency characteristic adjusters, the temperature stability of the dielectric materials can be greatly improved to meet the actual application needs.

[0041] In addition, the microwave dielectric ceramic materials obtained from Examples 1-9 and Comparative Example 1-5 were subjected to XRD testing, and the results are shown in Figure 1 , Figure 2 From the XRD characterization results, it can be seen that the system is still a single-phase structure after multi-component solid solution, and no second phase is generated, which indicates that the ceramic forms a continuous solid solution in the composition interval range of the present application, and indicates that the crystal structure can be directly and effectively adjusted by component design, thereby improving the performance of the ceramic. Comparative Example 7 indicates that the components cannot be solid-soluted to form the target phase structure, and thus the τ f value is negative, the temperature stability is poor, and it cannot be used as a temperature-frequency characteristic adjuster.

[0042] The above examples are only examples, and according to actual needs, (Ba xSr y Ca z The values of x, y, z in the 3MgSi2O8ceramics. For example, by comparing Examples 1-9 with Comparative Examples 1-7, it is not difficult to find that adjusting the coefficients x, y can obviously adjust the relative dielectric constant and the temperature coefficient of resonant frequency of the system; similarly, adjusting the coefficients x, z or adjusting x, y, z can all bring different ε r , Qf, τ f performances. As shown in Table 2, when 0.25≤x≤0.75, 0.25≤y≤0.75 and z=0, there are good low ε r , high Qfand τ f performances, and the overall performance is good.

[0043] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Use of a microwave dielectric ceramic material as a microwave dielectric ceramic temperature coefficient adjuster, characterized in that, The chemical formula of microwave dielectric ceramic material is (Ba x Sr y Ca z 3MgSi2O8, where 0 < x < 1, 0 ≤ y < 1, 0 ≤ z < 1, and x + y + z = 1; and when z = 0, 0.25 ≤ x ≤ 0.75, 0.25 ≤ y ≤ 0.75; when z ≠ 0, 0.33 ≤ x ≤ 0.34, 0 ≤ y ≤ 0.66; The microwave dielectric ceramic material can adjust the temperature coefficient of the resonance frequency of the whole ceramic system by adding.

2. The use according to claim 1, characterized in that, (Ba x Sr y Ca z )3MgSi2O8, 0.25≤x≤0.75, 0.25≤y≤0.75 and z=0.

3. Use according to claim 1 or 2, characterized in that, The microwave dielectric ceramic material is sintered in air or a reducing atmosphere.

4. Use of a microwave dielectric ceramic material as a microwave dielectric material, characterized in that The chemical formula of the microwave dielectric ceramic material is (Ba x Sr y Ca z )3MgSi2O8, wherein 0 0.25≤x≤0.75, 0.25≤y≤0.75; when z≠0, 0.33≤x≤0.34, 0≤y≤0.

66. The relative dielectric constant ε of the microwave dielectric ceramic material r ∈[13.67, 15.80], the quality factor Qf ∈ [10938, 24862] GHz, the resonance frequency temperature coefficient τ f ∈[8, 235] ppm / ℃.

5. The use according to claim 4, wherein the compound is ###0002### (Ba x Sr y Ca z )3MgSi2O8, x, y, z are located in the interval [0.33, 0.34]; accordingly, the relative dielectric constant ε of the microwave dielectric ceramic material is r ∈[15.64, 15.80], the quality factor Qf is ∈[10938, 15998]GHz, and the resonance frequency temperature coefficient τ f ∈[8, 10]ppm / ℃.

6. A microwave dielectric ceramic material characterized by, (Ba x Sr y Ca z )3MgSi2O8, wherein 0 < x < 1, 0 ≤ y < 1, 0 ≤ z < 1, and x + y + z = 1; and when z = 0, 0.25 ≤ x ≤ 0.75, 0.25 ≤ y ≤ 0.75; when z ≠ 0, 0.33 ≤ x ≤ 0.34, 0 ≤ y ≤ 0.66; The relative permittivity ε of the microwave dielectric ceramic material r ∈[13.67, 15.80], quality factor Qf∈[10938, 24862]GHz, temperature coefficient of resonant frequency τ f ∈[8,235]ppm / ℃.

7. The microwave dielectric ceramic material of claim 6, wherein, (Ba x Sr y Ca z )3MgSi2O8, x, y, z are located in the interval [0.33, 0.34]; accordingly, the relative dielectric constant ε r of the microwave dielectric ceramic material is in the interval [15.64, 15.80], the quality factor Qf is in the interval [10938, 15998] GHz, and the resonance frequency temperature coefficient τ f is in the interval [8, 10] ppm / ℃.

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