Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material and preparation method thereof

Abstract

The invention relates to the technical field of inorganic non-metallic materials, in particular to a Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material and a preparation method of the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material. According to the invention, Li3Mg2NbO6 is used as a matrix, Nb < 5 + > is partially replaced by V < 5 + >, Mg < 2 + > is partially replaced by Ni < 2 + >, the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material is prepared, the chemical expression is Li3Mg2-xNixNb < 1-y > VyO6, x = y, and 0 lt; and x is less than or equal to 0.04. Through synergistic doping of Ni < 2 + > and V < 5 + >, the sintering temperature is remarkably reduced under the condition that the original microwave dielectric property is stable, and the problem of parameter balance among the dielectric constant, the quality factor and the temperature coefficient of resonance frequency in performance optimization of the low-dielectric-loss microwave dielectric ceramic is solved; and the problem that the dielectric property is unstable due to the fact that impurities are possibly introduced into the added sintering aid is solved.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic materials technology, specifically to a Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material and its preparation method. Background Technology

[0002] With the rapid development of wireless communication technology towards higher-speed communication, increasingly higher demands are being placed on the performance of communication equipment. Microwave dielectric ceramics, as the core basic material for wireless communication devices, directly affect communication quality and efficiency. Low-dielectric-loss microwave dielectric ceramics, as an important category of microwave dielectric ceramics, have received widespread attention and in-depth research in recent years.

[0003] As communication frequencies continue to expand to higher frequencies, signal delay and signal attenuation problems become increasingly prominent. Low-dielectric-loss microwave dielectric ceramics can effectively reduce dielectric loss during signal propagation and improve signal transmission quality. In fields with extremely stringent requirements for dielectric loss, such as 5G and future network technologies, satellite communications, and military radar, low-dielectric-loss microwave dielectric ceramic systems are widely used due to their high quality factor. However, low-dielectric-loss microwave dielectric ceramics face multiple challenges in performance optimization and fabrication processes. In terms of performance, there is a parameter trade-off between dielectric constant, quality factor, and temperature coefficient of resonant frequency, making it difficult to achieve a high quality factor with low-dielectric-constant materials. Q×f Furthermore, component control can easily lead to performance degradation. During the manufacturing process, the added sintering aids may introduce impurities, resulting in increased losses and consequently reduced dielectric stability. All of these factors limit its application in the field of high-frequency communication. Summary of the Invention

[0004] To address the challenge of balancing dielectric constant, quality factor, and temperature coefficient of resonant frequency in optimizing the performance of low-dielectric microwave dielectric ceramics, and to mitigate the problem of impurities introduced by added sintering aids leading to unstable dielectric properties, this invention provides a Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material and its preparation method. This invention reduces the sintering temperature of Li3Mg2NbO6-based ceramics while maintaining a low dielectric constant, and improves the material's quality factor (…). Q×f )value.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows.

[0006] The first aspect of this invention provides a Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material, wherein the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material uses Li3Mg2NbO6 as a matrix and is applied through V... 5+ Partially replaces Nb 5+ Ni 2+ Partially replaces Mg2+ The chemical formula for the prepared Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material is: Li3Mg 2-x Ni x Nb 1-y V y O6, where x=y, and 0 <x≤0.04。

[0007] This invention uses Li3Mg2NbO6 as the matrix and utilizes V 5+ Replace Nb 5+ and Ni 2+ Replacement of Mg 2+ The microwave dielectric properties of Li3Mg2NbO6 material were modulated to reduce the sintering temperature and improve the material's quality factor. Q×f The goal is to meet the usage requirements of the microwave frequency band.

[0008] Preferably, 0.02 ≤ x ≤ 0.03. x represents Ni. 2+ Partially replaces Mg 2+ The doping amount; y represents V 5+ Partially replaces Nb 5+ The doping level. This invention utilizes Ni... 2+ With V 5+ By co-doping and by controlling the chemical composition, the original microwave dielectric properties are kept stable, the sintering temperature is significantly reduced, and the quality factor is significantly improved to 121400GHz~124200GHz.

[0009] A second aspect of this invention provides a method for preparing a Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material, comprising the following steps: With Li + Mg 2+ 、Nb 5+ V 5+ and Ni 2+ Using inorganic salts or oxides as raw materials, and according to the stoichiometric ratio of the chemical expression of Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material, the raw materials are ball-milled and pre-fired to prepare a mixed powder; the mixed powder is then pressed into shape and sintered to obtain Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material.

[0010] Preferably, the particle size of the mixed powder is between 60 mesh and 120 mesh. This invention selects mixed powder with particle sizes between the aperture of a 60-mesh sieve and a 120-mesh sieve to obtain uniform and fine raw material powder for preparing uniform and dense ceramic materials.

[0011] Preferably, the sintering temperature is 1000℃~1280℃, and the sintering time is 3h~5h. Preferably, the sintering temperature is 1020℃~1080℃.

[0012] For example, when x = y = 0, the sintering conditions are 1200℃ / 4h, 1220℃ / 4h, 1240℃ / 4h, 1260℃ / 4h, and 1280℃ / 4h.

[0013] x = y = 0.01, and the sintering conditions are 1040℃ / 4h, 1060℃ / 4h, 1080℃ / 4h, 1100℃ / 4h, and 1120℃ / 4h.

[0014] x = y = 0.02, and the sintering conditions are 1020℃ / 4h, 1040℃ / 4h, 1060℃ / 4h, 1080℃ / 4h, and 1100℃ / 4h.

[0015] x = y = 0.03, and the sintering conditions are 1000℃ / 4h, 1020℃ / 4h, 1040℃ / 4h, 1060℃ / 4h, and 1080℃ / 4h.

[0016] x = y = 0.04, and the sintering conditions are 1000℃ / 4h, 1020℃ / 4h, 1040℃ / 4h, 1060℃ / 4h, and 1080℃ / 4h.

[0017] This invention improves the quality factor and reduces dielectric loss of low-dielectric-loss microwave dielectric ceramic materials by optimizing the sintering conditions at corresponding doping levels.

[0018] Preferably, the raw material is Li + Mg 2+ 、Nb 5+ V 5+ and Ni 2+ Inorganic salts or oxides. Specifically, the raw materials are Li₂CO₃, MgO, Nb₂O₅, V₂O₅, and NiO.

[0019] Preferably, prior to sintering, a debinding operation is also included to remove the polyvinyl alcohol solution.

[0020] Preferably, the specific operation of the ball milling pre-firing treatment is as follows: Using water as the ball milling medium, the raw materials are first ball milled, dried, and then pre-calcined. The pre-calcined powder is then ball milled a second time, and then polyvinyl alcohol solution is added for granulation to obtain a mixed powder.

[0021] Through two - stage ball milling and pre - sintering, the raw materials undergo preliminary chemical reactions to form the target precursor and remove volatile impurities, thereby forming powders with appropriate particle sizes.

[0022] Preferably, the pre - sintering temperature is 860°C to 1100°C, and the pre - sintering time is 4h to 6h.

[0023] Preferably, the pre - sintering temperature is 860°C to 880°C.

[0024] Preferably, when 0 < x < 0.01, the pre - sintering temperature is 1100°C and the pre - sintering time is 5h.

[0025] When 0.01 ≤ x ≤ 0.03, the pre - sintering temperature is 860°C and the pre - sintering time is 5h.

[0026] When 0.03 < x ≤ 0.04, the pre - sintering temperature is 880°C and the pre - sintering time is 5h.

[0027] For example, when x = y = 0, it is 1100°C / 5h; when x = y = 0.01, 0.02, 0.03, it is 860°C / 5h; when x = y = 0.04, it is 880°C / 5h. The heating rate is 3°C / min.

[0028] The heating rate of pre - sintering is 3°C / min to 5°C / min.

[0029] Preferably, the mass fraction of the polyvinyl alcohol solution is 6% to 7%. In this invention, the main function of the polyvinyl alcohol solution is as a binder and granulation aid. Among them, a 7% mass - fraction PVA solution is suitable for ceramic powder granulation, which can be adjusted according to the specific surface area of the powder to avoid excessive adhesion.

[0030] Preferably, the mass ratio of zirconia balls, raw materials to the ball - milling medium is 20:1:2.

[0031] Advantages of this invention: 1. This invention uses Li3Mg2NbO6 as the matrix, and through V 5+ partially replacing Nb 5+ , Ni 2+ partially replacing Mg 2+ , prepares low - dielectric microwave dielectric ceramic materials by regulating the chemical composition. This invention utilizes V 5+ replacing Nb 5+ and Ni 2+ replacing Mg 2+ to regulate the microwave dielectric properties of the Li3Mg2NbO6 material, so as to reduce the sintering temperature and improve the quality factor of the material ( Q×fThe goal is to meet the usage requirements of the microwave frequency band, which can be used in fields such as communication, satellite navigation and positioning systems, and medium and short-range radar systems.

[0032] 2. In this invention, due to Ni 2+ With Mg 2+ V 5+ With Nb 5+ While achieving isovalent substitution, a significant size difference exists. This difference disrupts the original lattice perfection, inducing numerous lattice vacancies and micro-distortions, drastically reducing the activation energy for atomic diffusion, allowing the ceramic to achieve particle fusion and densification at lower temperatures. Furthermore, since the melting point of V₂O₅ is much lower than that of Nb₂O₅, during sintering, V… 5+ A small amount of liquid phase easily forms at the grain boundaries, filling the intergranular spaces and accelerating the Ni reaction. 2+ Mg 2+ Plasma diffusion promotes rapid growth of the sintering neck and reduces the sintering temperature.

[0033] 3. In this invention, V 5+ There may be some valence state fluctuations in the crystal lattice, which are related to Ni. 2+ Synergistic effects allow for precise adjustment of carrier concentration and mobility in materials, improving dielectric constant stability. This is achieved through Ni... 2+ With V 5+ Synergistic substitution inhibits excessive grain growth, forming a uniform and fine grain structure and reducing defects such as pores; and low-temperature liquid phase assistance significantly improves the density of ceramics, ultimately optimizing the dielectric properties of the material.

[0034] 4. This invention utilizes Ni 2+ With V 5+ Co-doping significantly reduces the sintering temperature and noticeably improves the quality factor while maintaining the stability of the original microwave dielectric properties. Q×f The GHz range reaches 121400 GHz to 124200 GHz. The preparation process of this invention is simple and environmentally friendly, and has great industrial application value. Attached Figure Description

[0035] Figure 1 The curves showing the change in bulk density as a function of sintering temperature for the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic materials prepared in Examples 1 to 5 are shown. Figure 1 The illustration shows the volume density curve of the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material prepared in Example 1 as a function of sintering temperature.

[0036] Figure 2 The X-ray diffraction patterns are those of the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic materials prepared in Examples 1 to 5.

[0037] Figure 3 The images shown are scanning electron microscope (SEM) images of the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic materials prepared in Examples 1 to 5. Specifically, (a) is an SEM image of the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material prepared in Example 1; (b) is an SEM image of the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material prepared in Example 2; (c) is an SEM image of the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material prepared in Example 3; (d) is an SEM image of the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material prepared in Example 4; and (e) is an SEM image of the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material prepared in Example 5.

[0038] Figure 4 The graph shows the change in dielectric constant of the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic materials prepared in Examples 1 to 5 as a function of sintering temperature. Figure 4 The illustration shows the change in dielectric constant of the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material prepared in Example 1 as a function of sintering temperature.

[0039] Figure 5 The graph shows the quality factor of the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic materials prepared in Examples 1 to 5 as a function of temperature. Figure 5 The illustration shows the quality factor of the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material prepared in Example 1 as a function of temperature.

[0040] Figure 6 The graph shows the temperature coefficient of the resonant frequency of the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic materials prepared in Examples 1 to 5 as a function of doping amount.

[0041] Figure 7 The graph shows the variation of quality factor, dielectric constant, and temperature coefficient of resonant frequency of the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic materials prepared in Examples 1 to 5 with the doping amount at the optimal sintering temperature. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] In the following embodiments, Q×f The quality factor is used to comprehensively evaluate the dielectric loss characteristics of a material at different resonant frequencies. Q×f The higher the value, the lower the dielectric loss and the better the performance of the material in high-frequency applications. τ ƒ The temperature coefficient represents the resonant frequency, reflecting the stability of the resonant frequency as it changes with temperature. τ ƒ The smaller the absolute value, the more stable the performance under temperature fluctuations.

[0045] This invention utilizes V 5+ Replace Nb 5+ and Ni 2+ Replacement of Mg 2+ The microwave dielectric properties of Li3Mg2NbO6 material were modulated to reduce the sintering temperature and improve the material's quality factor. Q×f The goal is to meet the usage requirements of the microwave frequency band. The specific reasons are as follows:

[0046] First, because Ni 2+ (r=0.069nm) and Mg 2+ (r=0.072nm), V 5+ (r=0.059nm) and Nb 5+ (r=0.064nm) represents isovalent substitution, but there is a significant size difference. This difference disrupts the perfection of the original crystal lattice, inducing a large number of lattice vacancies and micro-distortions, which greatly reduces the activation energy of atomic diffusion, allowing the ceramic to complete particle fusion and densification at a lower temperature.

[0047] Furthermore, the melting point of V₂O₅ is much lower than that of Nb₂O₅. During the sintering process, V… 5+ A small amount of liquid phase easily forms at the grain boundaries, filling the intergranular spaces and accelerating the Ni reaction. 2+ Mg 2+ Plasma diffusion promotes rapid growth of the sintering neck and reduces the sintering temperature.

[0048] And V 5+ There may be some valence state fluctuations in the crystal lattice, which are related to Ni. 2+ Synergistic substitution allows for precise adjustment of carrier concentration and mobility in materials, improving dielectric constant stability. It also suppresses excessive grain growth, resulting in a uniform and fine grain structure and reducing defects such as porosity. Furthermore, the low-temperature liquid phase assistance significantly enhances ceramic density, ultimately optimizing the material's dielectric properties.

[0049] Optionally, the Li3Mg 2-x Ni x Nb 1-y V y The optimal sintering parameters for O6 low dielectric loss microwave dielectric ceramic material are as follows: when x = y = 0, the optimal sintering parameter is 1220℃ / 4h; when x = y = 0.01, the optimal sintering parameter is 1080℃ / 4h; when x = y = 0.02, the optimal sintering parameter is 1040℃ / 4h; when x = y = 0.03, the optimal sintering parameter is 1020℃ / 4h; when x = y = 0.04, the optimal sintering parameter is 1020℃ / 4h.

[0050] The Li3Mg 2-x Ni x Nb 1-y V y The dielectric constants of O6 low dielectric loss microwave dielectric ceramic material at the optimal sintering temperature are as follows: 12.53 when x = y = 0; 12.36 when x = y = 0.01; 12.45 when x = y = 0.02; 12.33 when x = y = 0.03; and 12.2 when x = y = 0.04.

[0051] The Li3Mg 2-x Ni x Nb 1-y V y The quality factor of O6 low dielectric loss microwave dielectric ceramic material at the optimal sintering temperature is as follows: when x = y = 0, the quality factor is 103500 GHz; when x = y = 0.01, the quality factor is 104100 GHz; when x = y = 0.02, the quality factor is 124200 GHz; when x = y = 0.03, the quality factor is 121400 GHz; and when x = y = 0.04, the quality factor is 101500 GHz.

[0052] The Li3Mg 2-x Ni x Nb 1-y V yThe resonant frequency temperature coefficients of O6 low dielectric loss microwave dielectric ceramic material at the optimal sintering temperature are as follows: -29.26 ppm / ℃ when x = y = 0; -26.36 ppm / ℃ when x = y = 0.01; -26.26 ppm / ℃ when x = y = 0.02; -26.11 ppm / ℃ when x = y = 0.03; and -31.7 ppm / ℃ when x = y = 0.04.

[0053] The technical solution of the present invention will be further described below through specific embodiments.

[0054] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available.

[0055] The purity of Li₂CO₃ is 99.9%; the purity of MgO is 99.9%; the purity of Nb₂O₅ is 99.99%; the purity of V₂O₅ is 99.99%; and the purity of NiO is 99.8%. Example 1 A low dielectric loss microwave dielectric ceramic material, with the chemical composition formula Li3Mg2NbO6, is prepared by the following steps: Using Li2CO3, MgO, and Nb2O5 as raw materials, the mass of each raw material required for ceramic preparation was calculated according to the different doping amounts. Specifically, 8.5514 g of Li2CO3, 6.218 g of MgO, and 10.2464 g of Nb2O5 were required.

[0056] The weighed raw material powder and zirconia balls were placed in a ball mill jar, and deionized water was added as the ball milling medium. The mass ratio of zirconia balls, raw material powder and deionized water was 20:1:2. The ball mill speed was 300 r / min. After ball milling for 8 hours, the slurry in the ball mill jar was poured into a beaker and placed in an oven for drying at 110℃.

[0057] After drying, the dry material is placed in a mortar and ground into powder of appropriate particle size. After passing through a 60-mesh sieve, it is placed in a clean Al2O3 crucible and placed in a muffle furnace. It is then pre-fired at 1100℃ and kept at that temperature for 5 hours to obtain the pre-fired powder.

[0058] In order to obtain uniform and fine raw material powder and prepare uniform and dense ceramic materials, the pre-fired powder is ground and placed in a ball mill jar with zirconia balls. About 2 / 3 of the ball mill jar is filled with deionized water as the ball milling medium, and a second ball milling is carried out. The ball milling time is still 8 hours, and then the powder is dried.

[0059] The dried material is ground into powder. A 6%–7% polyvinyl alcohol solution is added to the powder for granulation. The powder is then passed through a 60-mesh sieve and a 120-mesh sieve. The intermediate powder with a particle size between 60 and 120 mesh is placed in a mold and pressed into a cylinder with a diameter of 10 mm and a height of 6 mm–7 mm. The pressure is 18 MPa–20 MPa, and the holding time is 2 min–3 min.

[0060] The pressed cylinders were placed into a crucible, which was then placed in a muffle furnace for debinding. The debinding was carried out at 600℃ for 2 hours to remove the polyvinyl alcohol solution added during granulation. After debinding, the cylinders were sintered at 1200℃ / 4h, 1220℃ / 4h, 1240℃ / 4h, 1260℃ / 4h, and 1280℃ / 4h, respectively, with a heating rate of 3℃ / min for all debinding sintering processes, resulting in low dielectric loss microwave dielectric ceramic materials.

[0061] The volume density and dielectric properties of low dielectric loss microwave dielectric ceramic materials prepared under different sintering conditions in Example 1 were tested. Q×f value and τ ƒ Value, result as Figure 1 as well as Figures 4 to 7 As shown. The results indicate that the optimal sintering temperature after ceramic formation in Example 1 is 1220℃, at which point the dielectric properties are... r = 12.53, Q×f = 103500GHz, τ ƒ = -29.26ppm / ℃. The X-ray diffraction pattern of the low-dielectric-loss microwave dielectric ceramic material in Example 1 is as follows: Figure 2 As shown; Scanning electron microscope (SEM) images are as follows. Figure 3 As shown. x=0 represents the low dielectric loss microwave dielectric ceramic material prepared by sintering at 1220℃ in Example 1.

[0062] Example 2 A low-dielectric-loss microwave dielectric ceramic material based on Li3Mg2NbO6, using Li3Mg2NbO6 as the substrate, is obtained through V 5+ Replace Nb 5+ Ni 2+ Replacement of Mg 2+ Prepare low dielectric loss microwave dielectric ceramic material with the chemical composition formula Li3Mg 1.99 Ni 0.01 Nb 0.99 V 0.01 O6, the preparation method of which specifically includes the following steps: Using Li2CO3, MgO, Nb2O5, V2O5, and NiO as raw materials, the mass of each raw material required for ceramic preparation was calculated according to the different doping amounts. Specifically, 8.5534 g of Li2CO3, 6.1883 g of MgO, 10.1463 g of Nb2O5, 0.0701 g of V2O5, and 0.0557 g of NiO were required.

[0063] The weighed raw material powder and zirconia balls were placed in a ball mill jar, and deionized water was added as the ball milling medium. The mass ratio of zirconia balls, raw material powder and deionized water was 20:1:2. The ball mill speed was 300 r / min. After ball milling for 8 hours, the slurry in the ball mill jar was poured into a beaker and placed in an oven for drying at 110℃.

[0064] After drying, the dry material is placed in a mortar and ground into powder of appropriate particle size. After passing through a 60-mesh sieve, it is placed in a clean Al2O3 crucible and placed in a muffle furnace. It is then pre-fired at 860℃ and held for 5 hours to obtain the pre-fired powder.

[0065] In order to obtain uniform and fine raw material powder and prepare uniform and dense ceramic materials, the pre-fired powder is ground and placed in a ball mill jar with zirconia balls. About 2 / 3 of the ball mill jar is filled with deionized water as the ball milling medium, and a second ball milling is carried out. The ball milling time is still 8 hours, and then the powder is dried.

[0066] The dried material is ground into powder. A 6%–7% polyvinyl alcohol solution is added to the powder for granulation. The powder is then passed through a 60-mesh sieve and a 120-mesh sieve. The intermediate powder with a particle size between 60 and 120 mesh is placed in a mold and pressed into a cylinder with a diameter of 10 mm and a height of 6 mm–7 mm. The pressure is 18 MPa–20 MPa, and the holding time is 2 min–3 min.

[0067] The pressed cylinders were placed into a crucible, which was then placed in a muffle furnace for debinding. The debinding was carried out at 600℃ for 2 hours to remove the polyvinyl alcohol solution added during granulation. After debinding, the cylinders were sintered at 1040℃ / 4h, 1060℃ / 4h, 1080℃ / 4h, 1100℃ / 4h, and 1120℃ / 4h, respectively. The heating rate of the debinding sintering was 3℃ / min, resulting in Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material.

[0068] The volume density and dielectric properties of Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic materials prepared under different sintering conditions in Example 2 were tested. Q×f value and τ ƒ Value, result as Figure 1 as well as Figures 4 to 7 As shown. The results indicate that the optimal sintering temperature after ceramic formation in Example 2 is 1080℃, at which point the dielectric properties are... r = 12.36, Q×f = 104100 GHz, τ ƒ = -26.36 ppm / ℃. The X-ray diffraction pattern of the low-dielectric-loss microwave dielectric ceramic material in Example 2 is shown below. Figure 2 As shown; Scanning electron microscope (SEM) images are as follows. Figure 3 As shown. x=0.01 represents the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material prepared by sintering at 1080℃ in Example 2.

[0069] Example 3 A low-dielectric-loss microwave dielectric ceramic material based on Li3Mg2NbO6, using Li3Mg2NbO6 as the substrate, is obtained through V 5+ Replace Nb 5+ Ni 2+ Replacement of Mg 2+ Low dielectric loss microwave dielectric ceramics were prepared, with the chemical composition formula Li3Mg. 1.98 Ni 0.02 Nb 0.98 V 0.02 O6, the preparation method of which specifically includes the following steps: Using Li2CO3, MgO, Nb2O5, V2O5, and NiO as raw materials, the mass of each raw material required for ceramic preparation was calculated according to the different doping amounts. Among them, Li2CO3 required 8.5554g, MgO required 6.1587g, Nb2O5 required 10.0462g, V2O5 required 0.1403g, and NiO required 0.1154g.

[0070] The weighed raw material powder and zirconia balls were placed in a ball mill jar, and deionized water was added as the ball milling medium. The mass ratio of zirconia balls, raw material powder and deionized water was 20:1:2. The ball mill speed was 300 r / min. After ball milling for 8 hours, the slurry in the ball mill jar was poured into a beaker and placed in an oven for drying at 110℃.

[0071] After drying, the dry material is placed in a mortar and ground into powder of appropriate particle size. After passing through a 60-mesh sieve, it is placed in a clean Al2O3 crucible and placed in a muffle furnace. It is then pre-fired at 860℃ and held for 5 hours to obtain the pre-fired powder.

[0072] In order to obtain uniform and fine raw material powder and prepare uniform and dense ceramic materials, the pre-fired powder was ground and placed in a ball mill jar with zirconia balls. About 2 / 3 of the ball mill jar was filled with deionized water as the ball milling medium, and a second ball milling was carried out. The ball milling time was still 8 hours.

[0073] The dried material is ground into powder. A 6%–7% polyvinyl alcohol solution is added to the powder for granulation. The powder is then passed through a 60-mesh sieve and a 120-mesh sieve. The intermediate powder with a particle size between 60 and 120 mesh is placed in a mold and pressed into a cylinder with a diameter of 10 mm and a height of 6 mm–7 mm. The pressure is 18 MPa–20 MPa, and the holding time is 2 min–3 min.

[0074] The pressed cylinders were placed into a crucible, and then the crucible was placed in a muffle furnace for debinding at 600℃ for 2 hours to remove the polyvinyl alcohol solution added during granulation. After debinding, the cylinders were sintered at 1020℃ / 4h, 1040℃ / 4h, 1060℃ / 4h, 1080℃ / 4h, and 1100℃ / 4h respectively to form ceramics. The heating rate of the debinding sintering was 3℃ / min, and Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material was obtained.

[0075] The volume density and dielectric properties of Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic materials prepared under different sintering conditions in Example 3 were tested. Q×f value and τ ƒ Value, result as Figure 1 as well as Figures 4 to 7 As shown. The results indicate that the optimal sintering temperature after ceramic formation in Example 3 is 1040℃, at which point the dielectric properties are... r = 12.45, Q×f = 124200 GHz, τ ƒ = -26.26 ppm / ℃. The X-ray diffraction pattern of the low-dielectric-loss microwave dielectric ceramic material in Example 3 is as follows: Figure 2 As shown; Scanning electron microscope (SEM) images are as follows. Figure 3 As shown. x=0.02 represents the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material prepared by sintering at 1040℃ in Example 3.

[0076] Example 4 A low-dielectric-loss microwave dielectric ceramic material based on Li3Mg2NbO6, using Li3Mg2NbO6 as the substrate, is obtained through V 5+ Replace Nb 5+ Ni 2+ Replacement of Mg 2+Low dielectric loss microwave dielectric ceramics were prepared, with the chemical composition formula Li3Mg. 1.97 Ni 0.03 Nb 0.97 V 0.03 O6, the preparation method of which specifically includes the following steps: Using Li2CO3, MgO, Nb2O5, V2O5, and NiO as raw materials, the mass of each raw material required for ceramic preparation was calculated according to the different doping amounts. Among them, Li2CO3 required 8.5574g, MgO required 6.1290g, Nb2O5 required 9.9460g, V2O5 required 0.2105g, and NiO required 0.1732g.

[0077] The weighed raw material powder and zirconia balls were placed in a ball mill jar, and deionized water was added as the ball milling medium. The mass ratio of zirconia balls, raw material powder and deionized water was 20:1:2. The ball mill speed was 300 r / min. After ball milling for 8 hours, the slurry in the ball mill jar was poured into a beaker and placed in an oven for drying at 110℃.

[0078] After drying, the dry material is placed in a mortar and ground into powder of appropriate particle size. After passing through a 60-mesh sieve, it is placed in a clean Al2O3 crucible and placed in a muffle furnace. It is then pre-fired at 860℃ and held for 5 hours to obtain the pre-fired powder.

[0079] In order to obtain uniform and fine raw material powder and prepare uniform and dense ceramic materials, the pre-fired powder was ground and placed in a ball mill jar with zirconia balls. About 2 / 3 of the ball mill jar was filled with deionized water as the ball milling medium, and a second ball milling was carried out. The ball milling time was still 8 hours.

[0080] The dried material is ground into powder. A 6%–7% polyvinyl alcohol solution is added to the powder for granulation. The powder is then passed through a 60-mesh sieve and a 120-mesh sieve. The intermediate powder with a particle size between 60 and 120 mesh is placed in a mold and pressed into a cylinder with a diameter of 10 mm and a height of 6 mm–7 mm. The pressure is 18 MPa–20 MPa, and the holding time is 2 min–3 min.

[0081] The pressed cylinders were placed into a crucible, and then the crucible was placed in a muffle furnace for debinding at 600℃ for 2 hours to remove the polyvinyl alcohol solution added during granulation. After debinding, the cylinders were sintered at 1000℃ / 4h, 1020℃ / 4h, 1040℃ / 4h, 1060℃ / 4h, and 1080℃ / 4h, respectively, with a heating rate of 3℃ / min for all debinding sintering processes, to obtain Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic materials.

[0082] The volume density and dielectric properties of Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic materials prepared under different sintering conditions in Example 4 were tested. Q×f value and τ ƒ Value, result as Figure 1 as well as Figures 4 to 7 As shown. The results indicate that the optimal sintering temperature after ceramic formation in Example 4 is 1020℃, at which point the dielectric properties are... r = 12.33, Q×f = 121400 GHz, τ ƒ = -26.11 ppm / ℃. The X-ray diffraction pattern of the low-dielectric-loss microwave dielectric ceramic material in Example 4 is shown below. Figure 2 As shown; Scanning electron microscope (SEM) images are as follows. Figure 3 As shown. x=0.03 represents the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material prepared by sintering at 1020℃ in Example 4.

[0083] Example 5 A low-dielectric-loss microwave dielectric ceramic material based on Li3Mg2NbO6, using Li3Mg2NbO6 as the substrate, is obtained through V 5+ Replace Nb 5+ Ni 2+ Replacement of Mg 2+ A low dielectric loss microwave dielectric ceramic, with the chemical composition formula Li3Mg 1.96 Ni 0.04 Nb 0.96 V 0.04 O6, the preparation method of which specifically includes the following steps: Using Li2CO3, MgO, Nb2O5, V2O5, and NiO as raw materials, the mass of each raw material required for ceramic preparation was calculated according to the different doping amounts. Among them, Li2CO3 required 8.5594g, MgO required 6.0993g, Nb2O5 required 9.8457g, V2O5 required 0.2807g, and NiO required 0.2310g.

[0084] The weighed raw material powder and zirconia balls were placed in a ball mill jar, and deionized water was added as the ball milling medium. The mass ratio of zirconia balls, raw material powder and deionized water was 20:1:2. The ball mill speed was 300 r / min. After ball milling for 8 hours, the slurry in the ball mill jar was poured into a beaker and placed in an oven for drying at 110℃.

[0085] After drying, the dry material is placed in a mortar and ground into powder of appropriate particle size. After passing through a 60-mesh sieve, it is placed in a clean Al2O3 crucible and placed in a muffle furnace. It is then pre-fired at 880℃ and kept at that temperature for 5 hours to obtain the pre-fired powder.

[0086] In order to obtain uniform and fine raw material powder and prepare uniform and dense ceramic materials, the pre-fired powder was ground and placed in a ball mill jar with zirconia balls. About 2 / 3 of the ball mill jar was filled with deionized water as the ball milling medium, and a second ball milling was carried out. The ball milling time was still 8 hours.

[0087] The dried material is ground into powder. A 6%–7% polyvinyl alcohol solution is added to the powder for granulation. The powder is then passed through a 60-mesh sieve and a 120-mesh sieve. The intermediate powder with a particle size between 60 and 120 mesh is placed in a mold and pressed into a cylinder with a diameter of 10 mm and a height of 6 mm–7 mm. The pressure is 18 MPa–20 MPa, and the holding time is 2 min–3 min.

[0088] The pressed cylinders were placed into a crucible, and then the crucible was placed in a muffle furnace for debinding at 600℃ for 2 hours to remove the polyvinyl alcohol solution added during granulation. After debinding, the cylinders were sintered at 1000℃ / 4h, 1020℃ / 4h, 1040℃ / 4h, 1060℃ / 4h, and 1080℃ / 4h, respectively, with a heating rate of 3℃ / min for all debinding sintering processes, to obtain Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic materials.

[0089] The volume density and dielectric properties of Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic materials prepared under different sintering conditions in Example 5 were tested. Q×f value and τ ƒ Value, result as Figure 1 as well as Figures 4 to 7 As shown. The results indicate that the optimal sintering temperature after ceramic formation in Example 5 is 1020℃, at which point the dielectric properties are... r = 12.20, Q×f = 101500 GHz, τ ƒ = -31.70 ppm / ℃. The X-ray diffraction pattern of the low-dielectric-loss microwave dielectric ceramic material in Example 5 is shown below. Figure 2 As shown; Scanning electron microscope (SEM) images are as follows. Figure 3 As shown. x=0.04 represents the Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material prepared by sintering at 1020℃ in Example 4.

[0090] Table 1 lists the microwave dielectric properties of the low dielectric loss microwave dielectric ceramic materials prepared in each embodiment.

[0091] Table 1 Microwave dielectric properties of low dielectric loss microwave dielectric ceramic materials Note: The chemical formula for low dielectric loss microwave dielectric ceramic material is Li3Mg 2-x Ni x Nb 1-y V y In O6, x represents the Ni doping level, and y represents the V doping level. The doping level specifically refers to the molar amount of dopant. r Indicates the dielectric constant; Q×f Indicates the quality factor; τ ƒ This represents the temperature coefficient of the resonant frequency.

[0092] From Table 1 and Figure 5 It can be seen that the quality factor of microwave dielectric ceramic materials increases significantly with the increase of NiO and V2O5 doping amount, but it shows a downward trend after the doping amount increases to x = y = 0.03.

[0093] This indicates that the quality factor of the low-dielectric-loss microwave dielectric ceramic material prepared in the embodiments of the present invention is increased, and the dielectric loss is smaller, thus improving the microwave dielectric properties. Furthermore, the low-dielectric-loss microwave dielectric ceramic material prepared in the embodiments of the present invention also exhibits good dielectric temperature stability within a temperature range of 25℃ to 85℃.

[0094] The embodiments of the present invention utilize Ni 2+ With V 5+ Co-doping significantly reduces the sintering temperature and substantially improves the quality factor to 121400GHz–124200GHz while maintaining the stability of the original microwave dielectric properties. The preparation process of this invention is simple and environmentally friendly, and has significant industrial application value.

[0095] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material, characterized in that, The low dielectric loss microwave dielectric ceramic material is based on Li3Mg2NbO6 and is applied through V... 5+ Partially replaces Nb 5+ Ni 2+ Partially replaces Mg 2+ The low dielectric loss microwave dielectric ceramic material prepared is chemically represented as Li3Mg. 2-x Ni x Nb 1-y V y O6, where x=y, and 0 <x≤0.04。 2. The Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material according to claim 1, characterized in that, 0.02≤x≤0.03。 3. A method for preparing a Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material, characterized in that, Includes the following steps: With Li + Mg 2+ 、Nb 5+ V 5+ and Ni 2+ Using inorganic salts or oxides as raw materials, and according to the stoichiometric ratio of the chemical expression of the low dielectric loss microwave dielectric ceramic material described in claim 1, the raw materials are ball-milled and pre-fired to prepare a mixed powder; the mixed powder is pressed into shape and then sintered to obtain Li3Mg2NbO6-based low dielectric loss microwave dielectric ceramic material.

4. The method for preparing the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material according to claim 3, characterized in that, The particle size of the mixed powder is between 60 mesh and 120 mesh.

5. The method for preparing the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material according to claim 3, characterized in that, The sintering temperature is 1000℃~1280℃, and the sintering time is 3h~5h.

6. The method for preparing the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material according to claim 5, characterized in that, The sintering temperature is 1020℃~1080℃.

7. The method for preparing the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material according to claim 3, characterized in that, The specific operation of the ball mill pre-firing treatment is as follows: Using water as the ball milling medium, the raw materials are first ball milled, dried, and then pre-calcined. The pre-calcined powder is then ball milled a second time, and then polyvinyl alcohol solution is added for granulation to obtain a mixed powder.

8. The method for preparing the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material according to claim 7, characterized in that, The preheating temperature is 860℃~1100℃, and the preheating time is 4h~6h.

9. The method for preparing the Li3Mg2NbO6-based low-dielectric-loss microwave dielectric ceramic material according to claim 3, characterized in that, The raw material is Li + Mg 2+ 、Nb 5+ V 5+ and Ni 2+ Inorganic salts or oxides.

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