Ligasiliconate microwave dielectric ceramic material with excess lithium and preparation method thereof

Abstract

The application discloses a LiGaSiO4 microwave dielectric ceramic material with excess lithium element and a preparation method thereof, and belongs to the technical field of electronic information functional material preparation. 1+x The preparation method of the LiGaSiO4 microwave dielectric ceramic material with excess lithium element comprises the following steps: according to the composition of LiGaSiO4 (0<=x<=0.08), Li2CO3, Ga2O3 and SiO2 are weighed, ground, and calcined to obtain a pre-prepared powder; a binder is added to the pre-prepared powder for granulation, compression molding and sintering to obtain the LiGaSiO4 microwave dielectric ceramic material. The application obtains a LiGaSiO4 microwave dielectric ceramic material with excess lithium element by using a non-stoichiometric method, alleviates crystal structure defects caused by Li volatilization in a high-temperature sintering process, improves ceramic density, and is more suitable for being used as a microwave dielectric ceramic.

Description

Technical Field

[0001] This invention relates to the field of electronic information functional material preparation technology, and in particular to a lithium-excess LiGaSiO4 microwave dielectric ceramic material and its preparation method. Background Technology

[0002] Microwave dielectric ceramics refer to ceramics used as dielectric materials in microwave (300MHz~300GHz) frequency band circuits, performing one or more functions. They are widely used in microwave components such as dielectric resonators, filters, duplexers, dielectric antennas, dielectric waveguide circuits, and dielectric antennas, and have become an important supporting material for modern communication technologies. With the rapid advancement of global 5G base station construction in the past two years, microwave dielectric ceramic components, represented by 5G macro base station dielectric waveguide filters, have ushered in tremendous development opportunities. At the same time, the development of communication technology demands microwave dielectric ceramics with superior performance. Recently, a series of low-dielectric (ε) ceramics have emerged for different application scenarios such as millimeter-wave communication, electronic circuit packaging, dielectric resonant antennas, base station communication, and miniaturized mobile communication. r ≤20), dielectric current (20<ε) r ≤60) and high dielectric (ε) r >60) Microwave dielectric ceramic materials.

[0003] A high quality factor is a key characteristic of microwave dielectric ceramics, reflecting their excellent frequency selectivity. However, materials containing volatile elements often exhibit increased crystal structure defects and porosity, leading to a decreased quality factor. For example, in LiGaSiO4 ceramics, the lithium element has a very low melting point and readily volatilizes during high-temperature sintering. This results in structural defects that limit its microwave dielectric properties (e.g., a low quality factor). Therefore, there is no existing record of LiGaSiO4 ceramics being used as microwave dielectric ceramics.

[0004] LiGaSiO4 ceramics belong to the trigonal crystal system with space group R3. All cations have two lattice sites, and all are four-coordinated. Each cation is located through O 2- Phase connection, each cation and O 2- It forms tetrahedrons. LiGaSiO4 has unique crystal structure characteristics, but structural defects caused by the volatilization of Li element limit its development in the field of dielectric materials. Summary of the Invention

[0005] The purpose of this invention is to provide a lithium-excess LiGaSiO4 microwave dielectric ceramic material and its preparation method. This invention utilizes a non-stoichiometric method to obtain a Li-excess LiGaSiO4 microwave dielectric ceramic material, mitigating crystal structure defects caused by Li volatilization during high-temperature sintering, improving ceramic density, and making it more suitable for use as a microwave dielectric ceramic.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions of this invention is to provide a method for preparing a lithium-excess LiGaSiO4 microwave dielectric ceramic material, comprising the following steps:

[0008] (1) According to Li 1+x The composition of GaSiO4 (0≤x≤0.08) is obtained by weighing Li2CO3, Ga2O3 and SiO2, grinding and calcining them to obtain a pre-made powder.

[0009] (2) Add a binder to the pre-made powder, granulate, press and sinter to obtain the LiGaSiO4 microwave dielectric ceramic material.

[0010] The chemical reaction involved in this invention is as follows:

[0011] Li2CO3+Ga2O3+2SiO2→2LiGaSiO4+CO2↑

[0012] Preferably, in step (1), x = 0.02, 0.04, 0.06 or 0.08.

[0013] Preferably, the grinding in step (1) is grinding until it passes through a 180-200 mesh sieve.

[0014] Preferably, the calcination temperature in step (1) is 900°C, the heating rate is 5°C / min, and the time is 4-8h.

[0015] Preferably, the binder in step (2) is a 5% polyvinyl alcohol solution by mass; the binder accounts for 3% of the mass fraction of the preformed powder.

[0016] Preferably, the pressure during the pressing process in step (2) is 20-30 MPa.

[0017] Preferably, the sintering temperature in step (2) is 950-1090℃, the heating rate is 5℃ / min, and the time is 4-8h.

[0018] The second technical solution of the present invention provides a LiGaSiO4 microwave dielectric ceramic material with excess lithium element obtained according to the above preparation method.

[0019] The third technical solution of the present invention provides an application of the above-mentioned LiGaSiO4 microwave dielectric ceramic material with excess lithium element in the preparation of microwave components.

[0020] The beneficial technical effects of the present invention are as follows:

[0021] This invention uses a traditional solid-state reaction method to prepare Li1+x For GaSiO4 (0 < x ≤ 0.08) microwave dielectric ceramic materials, appropriate high-temperature heat treatment is a necessary condition for powder densification to form ceramics. However, lithium is a low-melting-point element (~180℃), and partial volatilization occurs during high-temperature heating, leading to the appearance of oxygen vacancies and instability in the crystal structure, resulting in increased losses and negatively impacting microwave dielectric properties. Appropriate compensation of Li can alleviate the structural defects caused by its volatilization; however, excessive compensation can lead to the formation of a second phase, reducing density and also negatively affecting the microwave dielectric properties of the ceramic. This invention, through a series of explorations into lithium compensation amounts and raw material types, has obtained a Li-based ceramic with a uniform phase structure, good grain growth, and excellent microwave dielectric properties. 1+x GaSiO4 microwave dielectric ceramic material is a promising candidate formulation for high-performance microwave dielectric ceramic materials.

[0022] This invention utilizes a non-stoichiometric method to obtain a Li-excess LiGaSiO4 microwave dielectric ceramic material, mitigating crystal structure defects caused by Li volatilization during high-temperature sintering and improving ceramic density. The optimal microwave dielectric properties are achieved when x = 0.06, with a dielectric constant ε. r With a quality factor of 5.34 and a quality factor Q×f of 55600GHz, it is more suitable for use as a microwave dielectric ceramic. Attached Figure Description

[0023] Figure 1 The images show the XRD patterns of LiGaSiO4 ceramics prepared in Examples 1-4 and Comparative Example 3.

[0024] Figure 2 The images shown are SEM images of the products obtained in Examples 1-4. Among them, (a) is the SEM image of Example 1, (b) is the SEM image of Example 2, (c) is the SEM image of Example 3, and (d) is the SEM image of Example 4.

[0025] Figure 3 The image shows the XRD pattern of the LiGaSiO4 ceramic prepared in Comparative Example 1.

[0026] Figure 4 The image shows the XRD pattern of the LiGaSiO4 ceramic prepared in Comparative Example 2. Detailed Implementation

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0028] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] In the following embodiments and comparative examples of the present invention, the Li2CO3, Ga2O3 and SiO2 used are all of analytical grade.

[0032] In the following embodiments and comparative examples of the present invention, the adhesive used is a 5% polyvinyl alcohol solution by mass concentration.

[0033] All raw materials used in the following embodiments and comparative examples of the present invention are commercially available products.

[0034] Example 1

[0035] Preparation of LiGaSiO4 microwave dielectric ceramic material:

[0036] (1) According to Li 1+x The composition of GaSiO4 (x=0.02) is determined by weighing Li2CO3, Ga2O3 and SiO2, wet ball milling them until they pass through a 200-mesh sieve with deionized water as the ball milling medium, drying them, and then heating them to 900℃ at a heating rate of 5℃ / min and calcining them in an atmospheric atmosphere for 6 hours to obtain the pre-made powder.

[0037] (2) Add a binder equivalent to 3% of the mass fraction of the pre-made powder to the pre-made powder, granulate, dry press in a single-axis hydraulic press, then heat to 1050℃ at a heating rate of 5℃ / min and sinter in air atmosphere for 6h to obtain LiGaSiO4 (x=0.02) ceramic.

[0038] Li prepared in Example 1 1+x The XRD pattern of GaSiO4 (x = 0.02) ceramic is shown in [reference needed]. Figure 1 .Depend on Figure 1 It can be seen that the Li synthesized in this invention 1+xGaSiO4 (x = 0.02) ceramics are pure phase.

[0039] Li prepared in Example 1 1+x SEM images of GaSiO4 (x = 0.02) ceramics are shown below. Figure 2 As shown in the figure, the Li synthesized in this invention... 1+x GaSiO4 (x = 0.02) ceramics exhibited good crystallinity.

[0040] Example 2

[0041] Excess lithium 1+x Preparation of GaSiO4 microwave dielectric ceramic material:

[0042] (1) According to Li 1+x The composition of GaSiO4 (x=0.04) is determined by weighing Li2CO3, Ga2O3 and SiO2, wet ball milling them until they pass through a 200-mesh sieve with deionized water as the ball milling medium, drying them, and then heating them to 900℃ at a heating rate of 5℃ / min and calcining them in an atmospheric atmosphere for 6 hours to obtain the pre-made powder.

[0043] (2) Add a binder equivalent to 3% by mass of the pre-made powder, granulate, dry press in a single-shaft hydraulic press, then heat to 1050℃ at a heating rate of 5℃ / min and sinter in air atmosphere for 6h to obtain Li 1+ x GaSiO4 (x=0.04) ceramics.

[0044] Li prepared in Example 2 1+x The XRD pattern of GaSiO4 (x = 0.04) ceramic is shown in [reference needed]. Figure 1 As shown in the figure, the Li synthesized in this invention... 1+x GaSiO4 (x = 0.06) ceramics are pure phase.

[0045] Li prepared in Example 2 1+x SEM images of GaSiO4 (x = 0.04) ceramics are shown below. Figure 2 As shown in the figure, the Li synthesized in this invention... 1+x GaSiO4 (x=0.04) ceramics exhibited good crystallization.

[0046] Example 3

[0047] Excess lithium 1+x Preparation of GaSiO4 microwave dielectric ceramic material:

[0048] (1) According to Li 1+xThe composition of GaSiO4 (x=0.06) is determined by weighing Li2CO3, Ga2O3 and SiO2, wet ball milling them until they pass through a 200-mesh sieve with deionized water as the ball milling medium, drying them, and then heating them to 900℃ at a heating rate of 5℃ / min and calcining them in an atmospheric atmosphere for 6 hours to obtain the pre-made powder.

[0049] (2) Add a binder equivalent to 3% by mass of the pre-made powder, granulate, dry press in a single-shaft hydraulic press, then heat to 1050℃ at a heating rate of 5℃ / min and sinter in air atmosphere for 6h to obtain Li 1+ x GaSiO4 (x=0.06) ceramics.

[0050] Li prepared in Example 3 1+x The XRD pattern of GaSiO4 (x = 0.06) ceramic is shown in [reference needed]. Figure 1 .Depend on Figure 1 It can be seen that the Li synthesized in this invention 1+x GaSiO4 (x = 0.06) ceramics are pure phase.

[0051] Li prepared in Example 3 1+x SEM images of GaSiO4 (x = 0.06) ceramics are shown below. Figure 2 As shown in the figure, the Li synthesized in this invention... 1+x GaSiO4 (x = 0.06) ceramics exhibited good crystallization.

[0052] Example 4

[0053] The only difference from Example 1 is that Li2CO3, Ga2O3, and SiO2 are processed according to Li... 1+x The composition of GaSiO4 (x = 0.08) was weighed to obtain Li 1+x GaSiO4 (x=0.08) ceramics.

[0054] Li prepared in Example 4 1+x The XRD pattern of GaSiO4 (x = 0.08) ceramic is shown in [reference needed]. Figure 1 .Depend on Figure 1 It can be seen that the Li synthesized in this invention 1+x GaSiO4 (x = 0.08) ceramics are pure phase.

[0055] Li prepared in Example 4 1+x SEM images of GaSiO4 (x = 0.08) ceramics are shown below. Figure 2 As shown in the figure, the Li synthesized in this invention... 1+x GaSiO4 (x = 0.08) ceramics exhibited good crystallization.

[0056] Comparative Example 1

[0057] The only difference from Example 1 is that the sintering temperature in step (2) is 800°C.

[0058] The XRD pattern of the LiGaSiO4 ceramic prepared in Comparative Example 1 is shown in Figure 1. Figure 3 .Depend on Figure 3 It can be seen that the ceramic material prepared in Comparative Example 1 contains the impurity phase of LiGa5O8.

[0059] Comparative Example 2

[0060] The only difference from Example 1 is that Li2CO3, Ga2O3, and SiO2 are processed according to Li... 1+x The composition of GaSiO4 (x=0.10) was determined.

[0061] The XRD pattern of the LiGaSiO4 ceramic prepared in Comparative Example 2 is shown in Figure 2. Figure 4 .Depend on Figure 4 It can be seen that the ceramic material prepared in Comparative Example 2 contains the impurity phase of LiGa5O8.

[0062] Comparative Example 3

[0063] The only difference from Example 1 is that Li2CO3, Ga2O3, and SiO2 are processed according to Li... 1+x The composition of GaSiO4 (x=0) is determined.

[0064] The XRD pattern of the LiGaSiO4 ceramic prepared in Comparative Example 3 is shown in Figure 3. Figure 1 .Depend on Figure 1 It can be seen that Li in Comparative Example 3 1+x GaSiO4 (x=0) ceramics are pure phase.

[0065] Effect verification

[0066] (1) In order to verify the working performance of the product obtained by the present invention, the following tests were conducted on Examples 1-5, and the test results are shown in Table 1.

[0067] Table 1 Working Performance

[0068]

[0069] As shown in the table, the product with x = 0.06 has higher dielectric properties compared to products with other lithium addition amounts.

[0070] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a lithium-excess LiGaSiO4 microwave dielectric ceramic material, characterized in that, The steps are as follows: (1) According to Li 1+x The composition of GaSiO4 is obtained by weighing Li2CO3, Ga2O3 and SiO2, grinding and calcining them to obtain a pre-made powder. (2) Add a binder to the pre-made powder, granulate, press and sinter to obtain the LiGaSiO4 microwave dielectric ceramic material; In step (1), the x =0.02, 0.04, 0.06 or 0.08; the calcination temperature is 900℃, the heating rate is 5℃ / min, and the time is 4-8h; In step (2), the sintering temperature is 950-1090℃, the heating rate is 5℃ / min, and the time is 4-8h.

2. The preparation method according to claim 1, characterized in that, The grinding mentioned in step (1) is grinding until it passes through a 180-200 mesh sieve.

3. The preparation method according to claim 1, characterized in that, The adhesive in step (2) is a 5% polyvinyl alcohol solution by mass; the adhesive accounts for 3% of the mass fraction of the preformed powder.

4. The preparation method according to claim 1, characterized in that, The pressure during the pressing process described in step (2) is 20-30 MPa.

5. A lithium-excess LiGaSiO4 microwave dielectric ceramic material obtained by the preparation method according to any one of claims 1-4.

6. The application of the lithium-excess LiGaSiO4 microwave dielectric ceramic material as described in claim 5 in the fabrication of microwave components.

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