ZnxMg1-xF2 microwave dielectric ceramic and preparation method thereof

Abstract

The invention relates to the technical field of microwave dielectric ceramics, discloses a preparation method of a ZnxMg1-xF2 microwave dielectric ceramic and a ceramic material of the ZnxMg1-xF2 microwave dielectric ceramic, and is suitable for 5G / 6G high-frequency communication devices. In order to solve the problems that MgF2-based ceramic sintering densification is difficult and oxygenolysis is prone to occurring in the doping process, a ZnF2-doped MgF2 ceramic green body is sintered in an inert atmosphere, and material phase composition and a microstructure are effectively regulated and controlled. The preparation method comprises the steps of raw material proportioning, ball milling and mixing, forming and inert atmosphere sintering, wherein the doping amount x of ZnF2 is 0.5-1.0 mol%. By adopting the method, the ZnxMg1-xF2 microwave dielectric ceramic with relatively high density and few impure phases can be obtained, the relative dielectric constant of the ZnxMg1-xF2 microwave dielectric ceramic is 4.8-5.3, and the quality factor Qf of the ZnxMg1-xF2 microwave dielectric ceramic is not lower than 80k GHz. The method is stable in process, good in repeatability and suitable for preparation of low-loss microwave dielectric ceramics.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microwave dielectric ceramic materials, and particularly relates to a Zn x Mg 1-x F2 microwave dielectric ceramic and a preparation method thereof. BACKGROUND

[0002] With the rapid development of 5G communication technology, high-frequency devices have higher requirements for microwave dielectric materials. An ideal microwave dielectric material should have a low dielectric constant (εᵣ) to reduce signal delay, a high quality factor (Qf) to reduce energy loss, and ensure the stability of the communication system. Qf

[0003] Magnesium fluoride (MgF2) ceramics show great potential due to their intrinsic low dielectric constant (εᵣ ≈ 5.0) and low dielectric loss (tanδ < 50kGHz). However, pure MgF2 ceramics have problems such as poor sintering activity, high porosity, and difficulty in densification, which result in that the actual microwave dielectric performance is far from the theoretical expectation. Traditional solid-phase sintering methods are usually carried out in air atmosphere, which easily leads to oxidation of doped elements, produces impurities, and deteriorates the material performance. Qf SUMMARY

[0004] In view of the deficiencies of the prior art, the application provides a Zn x Mg 1-x F2 microwave dielectric ceramic and a preparation method thereof. The sintering in a nitrogen atmosphere effectively inhibits the oxidation and decomposition of ZnF2, and significantly improves the densification degree and microwave dielectric performance of the ceramic.

[0005] The technical scheme of the application is as follows: A preparation method of a Zn x Mg 1-x F2 microwave dielectric ceramic, comprising the following steps: (1) Raw material proportioning and mixing: high-purity MgF2 and ZnF2 are used as raw materials, and are weighed according to the chemical formula Zn x Mg 1-x F2. In the application, the doping amount of ZnF2 is preferably 0.5-1.0 mol%, and within the range, single-phase Zn x Mg 1- x F2 ceramic and excellent microwave dielectric performance can be stably obtained. The raw materials, ZrO2 grinding balls and anhydrous ethanol are placed in a planetary ball mill together for ball milling for 12 hours; (2) Drying and forming: the slurry obtained in step (1) is dried at 85℃ for 24 hours, then ground and sieved, and pressed into a ceramic green body; ​​(3) Atmosphere sintering: the green body is placed in an inert atmosphere sintering furnace, and heated to 900-1000℃ at a rate of 5℃ / min, and kept for 3 hours, and cooled with the furnace.

[0006] As a preferred solution, the inert atmosphere in step (3) effectively inhibits the oxidative decomposition of ZnF2, avoiding the generation of ZnO second phase.

[0007] As a preferred solution, the doping amount of ZnF2 is x 0.75 mol%, under which the ceramic obtains better microwave dielectric properties.

[0008] As a preferred solution, the sintering temperature in step (3) is 975℃.

[0009] The present application also provides Zn x Mg 1-x F2 microwave dielectric ceramic prepared by the method of any one of the above technical solutions, under the sintering conditions of x = 0.75%, 975℃, and obtains better performance: relative dielectric constant ε r ≈ 5.09, quality factor Qf ≈ 104,351 GHz, and relative density is higher than 95%.

[0010] Compared with the prior art, the present application has the beneficial effects that: (1) The present application adopts inert atmosphere sintering, effectively inhibits the oxidative decomposition of ZnF2, avoids the generation of ZnO second phase, and significantly improves the densification degree and microwave dielectric properties of the ceramic; (2) By accurately controlling the doping concentration of ZnF2 x = 0.75%, better comprehensive performance is obtained under the sintering conditions of 975℃, Qf the value reaches 104,351 GHz, which is better than most low dielectric constant microwave dielectric materials; (3) Compared with air atmosphere sintering, the ceramic prepared under inert atmosphere has more uniform microstructure, higher density and better microwave dielectric properties; (4) The process of the present application is simple, has good repeatability, is suitable for large-scale production, and has broad application prospects in 5G / 6G high-frequency communication devices. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 XRD pattern of Zn x Mg 1-x F2 ceramic of the present application examples 1-5 sintered at 950℃; Figure 2 XRD pattern of Zn x Mg1-x The relative density of F2 ceramics varies with doping concentration; Figure 3 Zn in Embodiments 1-5 of the present invention x Mg 1-x Microwave dielectric properties of F2 ceramics Qf The value varies with doping concentration; Figure 4 Zn in Embodiments 1-5 of the present invention x Mg 1-x Microwave dielectric properties of F2 ceramics (dielectric constant ε) r The effect of doping concentration varies; Figure 5 Zn in Embodiment 6 of the present invention x Mg 1-x F2( x XRD pattern of ceramics sintered at 950℃ (= 0.75%). Figure 6 This is Example 6 of the present invention. x = 0.75%) Microwave dielectric properties sintered in air atmosphere ( Qf Values) graph; Figure 7 This is Embodiment 2 of the present invention. x XPS comparison of Example 6 (0.75%) with that of Comparative Example 6 (air atmosphere sintering); Detailed Implementation

[0012] The technical solution of the present invention will be further described and illustrated below through specific embodiments.

[0013] Sintering temperature (900 ℃ < T < 1000 ℃), time (t = 3 h) Example 1:

[0014] This embodiment describes a method for producing high-performance microwave dielectric ceramics, comprising the following steps: (1) Raw material proportioning and mixing: according to Zn 0.005 Mg 0.995 Weigh the raw materials according to the stoichiometric ratio of F2 and ball mill for 12 hours; (2) Drying: Dry the slurry from step (1) at 85°C for 24 hours, and then press it into shape; (3) Atmosphere sintering: In a nitrogen atmosphere, the temperature is increased to 900℃-1000℃ at a rate of 5℃ / min (each 25℃ is set as a sintering temperature point), and held for 3 hours. The mixture is then allowed to cool naturally to room temperature to obtain Zn. 0.005 Mg 0.995 F2 ceramics.

[0015] like Figure 1As shown, comparing the ceramic XRD pattern of Example 1 with the standard PDF card of MgF2, it can be seen that the ceramic composition obtained in this example is Zn. 0.005 Mg 0.995 F2.

[0016] like Figure 2 As shown, the Zn obtained in Example 1 0.005 Mg 0.995 The relative density of F2 ceramics at different sintering temperatures is as follows: the highest relative density is 95.6%.

[0017] like Figure 3 As shown, the Zn obtained in Example 1 0.005 Mg 0.995 F2 ceramics at different sintering temperatures Qf The value is 99.4k.

[0018] like Figure 4 As shown, the Zn obtained in Example 1 0.005 Mg 0.995 ε at different sintering temperatures of F2 ceramics r The value is 5.07, with a maximum value of 5.07.

[0019] Example 2: This embodiment describes a method for producing high-performance microwave dielectric ceramics, comprising the following steps: (1) Raw material proportioning and mixing: according to Zn 0.0075 Mg 0.9925 Weigh the raw materials according to the stoichiometric ratio of F2 and ball mill for 12 hours; (2) Drying: Dry the slurry from step (1) at 85°C for 24 hours, and then press it into shape; (3) Atmosphere sintering: In a nitrogen atmosphere, the temperature is increased to 900℃-1000℃ at a rate of 5℃ / min (each 25℃ is set as a sintering temperature point), and held for 3 hours. The mixture is then allowed to cool naturally to room temperature to obtain Zn. 0.0075 Mg 0.9925 F2 ceramics.

[0020] like Figure 1 As shown, comparing the ceramic XRD pattern of Example 1 with the standard PDF card of MgF2, it can be seen that the ceramic composition obtained in this example is Zn. 0.0075 Mg 0.9925 F2.

[0021] like Figure 2 As shown, the Zn obtained in Example 1 0.0075 Mg 0.9925 The relative density of F2 ceramics at different sintering temperatures is as follows: the highest relative density is 95.7%.

[0022] likeFigure 3 As shown, the Zn obtained in Example 1 0.0075 Mg 0.9925 F2 ceramics at different sintering temperatures Qf The value is 105.3k.

[0023] like Figure 4 As shown, the Zn obtained in Example 1 0.005 Mg 0.995 ε at different sintering temperatures of F2 ceramics r The value is 5.14, with a maximum value of 5.14.

[0024] Example 3:

[0025] This embodiment describes a method for producing high-performance microwave dielectric ceramics, comprising the following steps: (1) Raw material proportioning and mixing: according to Zn 0.01 Mg 0.99 Weigh the raw materials according to the stoichiometric ratio of F2 and ball mill for 12 hours; (2) Drying: Dry the slurry from step (1) at 85°C for 24 hours, and then press it into shape; (3) Atmosphere sintering: In a nitrogen atmosphere, the temperature is increased to 900℃-1000℃ at a rate of 5℃ / min (each 25℃ is set as a sintering temperature point), and held for 3 hours. The mixture is then allowed to cool naturally to room temperature to obtain Zn. 0.01 Mg 0.99 F2 ceramics.

[0026] like Figure 1 As shown, comparing the ceramic XRD pattern of Example 1 with the standard PDF card of MgF2, it can be seen that the ceramic composition obtained in this example is Zn. 0.01 Mg 0.99 F2.

[0027] like Figure 2 As shown, the Zn obtained in Example 1 0.01 Mg 0.99 The relative density of F2 ceramics at different sintering temperatures is as follows: the highest relative density is 95.7%.

[0028] like Figure 3 As shown, the Zn obtained in Example 1 0.01 Mg 0.99 F2 ceramics at different sintering temperatures Qf The value is 104.3k.

[0029] like Figure 4 As shown, the Zn obtained in Example 1 0.005 Mg 0.995 ε at different sintering temperatures of F2 ceramics r The value is 5.14, with a maximum value of 5.14.

[0030] Example 4:

[0031] This embodiment describes a method for producing high-performance microwave dielectric ceramics, comprising the following steps: (1) Raw material proportioning and mixing: according to Zn 0.03 Mg 0.97 Weigh the raw materials according to the stoichiometric ratio of F2 and ball mill for 12 hours; (2) Drying: Dry the slurry from step (1) at 85°C for 24 hours, and then press it into shape; (3) Atmosphere sintering: In a nitrogen atmosphere, the temperature is increased to 900℃-1000℃ at a rate of 5℃ / min (each 25℃ is set as a sintering temperature point), and held for 3 hours. The mixture is then allowed to cool naturally to room temperature to obtain Zn. 0.03 Mg 0.97 F2 ceramics.

[0032] like Figure 1 As shown, comparing the ceramic XRD pattern of Example 1 with the standard PDF card of MgF2, it can be seen that the ceramic composition obtained in this example is Zn. 0.03 Mg 0.97 F2 also shows a second phase that clearly corresponds to ZnO.

[0033] like Figure 2 As shown, the Zn obtained in Example 1 0.03 Mg 0.97 The relative density of F2 ceramics at different sintering temperatures is as follows: the highest relative density is 95.3%.

[0034] like Figure 3 As shown, the Zn obtained in Example 1 0.03 Mg 0.97 F2 ceramics at different sintering temperatures Qf The value is 71.5k.

[0035] like Figure 4 As shown, the Zn obtained in Example 1 0.005 Mg 0.995 ε at different sintering temperatures of F2 ceramics r The value is 5.16.

[0036] Example 5:

[0037] This embodiment describes a method for producing high-performance microwave dielectric ceramics, comprising the following steps: (1) Raw material proportioning and mixing: according to Zn 0.05 Mg 0.95 Weigh the raw materials according to the stoichiometric ratio of F2 and ball mill for 12 hours; (2) Drying: Dry the slurry from step (1) at 85°C for 24 hours, and then press it into shape; (3) Atmosphere sintering: In a nitrogen atmosphere, the temperature is increased to 900℃-1000℃ at a rate of 5℃ / min (each 25℃ is set as a sintering temperature point), and held for 3 hours. The mixture is then allowed to cool naturally to room temperature to obtain Zn. 0.05 Mg 0.95 F2 ceramics.

[0038] like Figure 1 As shown, comparing the ceramic XRD pattern of Example 1 with the standard PDF card of MgF2, it can be seen that the ceramic composition obtained in this example is Zn. 0.05 Mg 0.95 F2 also shows a second phase that clearly corresponds to ZnO.

[0039] like Figure 2 As shown, the Zn obtained in Example 1 0.05 Mg 0.95 The relative density of F2 ceramics at different sintering temperatures is as follows: the highest relative density is 95.4%.

[0040] like Figure 3 As shown, the Zn obtained in Example 1 0.05 Mg 0.95 F2 ceramics at different sintering temperatures Qf The value is 63.3k.

[0041] like Figure 4 As shown, the Zn obtained in Example 1 0.005 Mg 0.995 ε at different sintering temperatures of F2 ceramics r The value is 5.16.

[0042] Example 6: This embodiment describes a method for sintering microwave dielectric ceramics under different atmospheres, including the following steps: (1) Raw material proportioning and mixing: according to Zn 0.0075 Mg 0.9925 Weigh the raw materials according to the stoichiometric ratio of F2 and ball mill for 12 hours; (2) Drying: Dry the slurry from step (1) at 85°C for 24 hours, and then press it into shape; (3) Air atmosphere sintering: In an air atmosphere, the temperature is increased to 900℃-1000℃ at a rate of 5℃ / min (each 25℃ is set as a sintering temperature point), and held for 3 hours. The temperature is then naturally cooled to room temperature to obtain Zn. 0.0075 Mg 0.9925 F2 ceramics.

[0043] like Figure 5As shown, comparing the ceramic XRD pattern of Example 1 with the standard PDF cards for MgF2 and ZnO, it can be seen that the ceramic composition obtained in this example is Zn. 0.0075 Mg 0.9925 F2 and ZnO.

[0044] like Figure 6 As shown, the Zn obtained in Example 1 0.0075 Mg 0.9925 F2 ceramics at different sintering temperatures Qf The value is 18.2k.

[0045] like Figure 7 As shown in (a) and (b), Zn under different atmospheres 0.0075 Mg 0.9925 XPS spectra of F2 ceramics indicate that O under a nitrogen atmosphere 1s The spectrum only showed C=O (binding energy BE ≈ 531.5 eV) and CO (BE ≈ 532.5 eV) bonds from surface organic contaminants; no metal-oxygen bonds (such as Zn-O or Mg-O) were detected. This indicates that the inert atmosphere effectively suppressed the oxidation reaction on the sample surface, and F⁻ was not converted by O. 2- The surface is mainly composed of fluorides (MgF2, ZnF2); while the O in the air atmosphere... 1s The spectrum now includes a low BE component (BE ≈ 530.0 eV), corresponding to Zn. 2+ With O 2- The coordination is due to the thermodynamically favorable displacement reaction between O2 in the air and ZnF2 at high temperatures, which leads to the loss of F⁻ and the formation of Zn-O bonds. Figure 7 (c, d) For Zn 2p Spectrum, Zn in nitrogen atmosphere 2p3 / 2 The peak is symmetrical and sharp (BE ≈ 1021.8 eV), consistent with the characteristics of Zn-F bonds in ZnF2, indicating that Zn is chemically homogeneous under an inert atmosphere and exists entirely as Zn-F bonds; while Zn in an air atmosphere... 2p3 / 2 The peak was Zn-O (BE ≈ 1021.2 eV), which is due to the effect of O2 in the air atmosphere, causing ZnF2 to decompose and form ZnO. In summary, the sintering atmosphere has a significant regulatory effect on the surface chemical state of fluoride-doped samples. A nitrogen atmosphere is beneficial for maintaining a uniform chemical state of Zn (Zn-F) and a high F⁻ retention rate, while an air atmosphere leads to oxidation and chemical inhomogeneity. This result provides key surface chemical evidence for optimizing the sintering process of fluoride-doped samples to improve performance stability.

[0046] Zn obtained by Archimedes' displacement method and vector network analyzer x Mg 1-xThe performance parameters of F2 ceramics are listed in Table 1 below.

[0047] Table 1. High microwave dielectric properties of Zn in Examples 1-5 x Mg 1-x F2 ceramic parameter comparison table Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Sintering atmosphere [N2] [N2] [N2] [N2] [N2] AIR Maximum relative density (%) 95.6 95.7 95.7 95.3 95.4 91 Maximum 99.4k 105.3k 104.3k 71.5k 63.3k 18.2k dielectric constant ε r ]]> 5.07 5.14 5.14 5.16 5.16 / The first five embodiments described above show that as the sintering temperature increases, Qf The values ​​fluctuate significantly in terms of sintering temperature and composition. Overall, low doping ratios ( x ≤ 1%) of the sample Qf The value shows a continuous increase or a trend of first increasing and then stabilizing with increasing temperature, while the high doping ratio ( x =3%, 5%) samples Qf The value changes are quite different. The core reason for this deterioration trend is that, with high doping levels, ZnF2 exceeds its solid solubility in MgF2, leading to a decomposition reaction during high-temperature sintering and the formation of a ZnO second phase. However, in Example 6, during sintering in air... Qf The value is low, only 18.2 kJ, due to the presence of the ZnO phase, which is much lower than the composition sintered in nitrogen. This indicates that appropriate doping ( x = 0.75%) can significantly improve the densification degree and obtain better microwave performance (εᵣ = 5.09, Qf = 104,351 GHz), and the nitrogen atmosphere effectively suppresses ZnF2 oxidation and maintains Zn-F bond stability.

[0048] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A type of Zn x Mg 1-x The preparation method of F2 microwave dielectric ceramic is characterized by, Includes the following steps: 1) According to the general chemical formula Zn x Mg 1-x F2 contains raw materials, among which x The concentration is 0.5–1.0 mol%, and the raw materials include MgF2 powder and ZnF2 powder. 2) The raw materials are mixed with grinding media and organic solvent and then ball-milled to obtain a uniformly mixed slurry; 3) The slurry is dried, pulverized, and shaped to obtain a ceramic green body; 4) The ceramic green body is sintered in an inert atmosphere at a sintering temperature of 850–1050 °C. o C, after heat treatment and cooling, yields Zn. x Mg 1-x F2 microwave dielectric ceramic.

2. The preparation method according to claim 1, characterized in that, The inert atmosphere is nitrogen, argon, or a mixture thereof.

3. The preparation method according to claim 1 or 2, characterized in that, The heating rate for sintering is 1–10. o C / min, heat preservation time is 1–6h.

4. The preparation method according to claim 1, characterized in that, The ball milling time is 6–24 h, and the organic solvent is anhydrous ethanol.

5. The ceramic prepared by the method according to any one of claims 1–4 has a relative density of not less than 93%.

6. A type of Zn x Mg 1-x F2 microwave dielectric ceramic, characterized in that: The ceramic has a single fluoride main phase structure; its crystal structure is a MgF2 type solid solution structure; the ceramic is basically free of ZnO impurity phase; the relative permittivity of the ceramic is 4.8–5.3, and the quality factor is [missing information]. Qf No less than 80k GHz.

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