A-site ion co-doping regulated scheelite molybdenum-based microwave dielectric ceramic and preparation method thereof
By co-doping NaSrYbMo3O12 ceramics with A-site ions of Na, K, Sr and Ba, its crystal structure and dielectric properties are optimized, solving the problems of insufficient quality factor and resonant frequency temperature coefficient of existing ceramics, and realizing the applicability of low-temperature sintering and high-frequency communication devices.
Patent Information
- Application Number
- CN202511612253.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-06
- Publication Date
- 2026-01-09
AI Technical Summary
The quality factor and resonant frequency temperature coefficient of existing NaSrYbMo3O12 ceramics are insufficient to meet the requirements of high-performance microwave devices, and the high sintering temperature makes it difficult to co-fire with silver electrodes, thus limiting its application in multilayer devices.
Na1-xKxSr1-xBaxYbMo3O12 ceramics were prepared by co-doping A-site ions by adjusting the molar ratio of Na, K, Sr and Ba. The crystal structure and dielectric properties were optimized by using solid-state reaction sintering combined with ball milling, pre-firing, forming and high-temperature sintering processes.
Microwave dielectric ceramics with low dielectric constant, excellent temperature coefficient of resonant frequency and quality factor have been obtained, which are suitable for high-frequency communication device applications and can be sintered at low temperature, making them easy to mass-produce.
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Figure CN121292968A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microwave dielectric ceramics technology, specifically relating to an A-site ion co-doping controlled scheelite molybdenum-based microwave dielectric ceramic and its preparation method. Background Technology
[0002] With the rapid development of wireless communication technology towards higher frequencies, greater integration, and low-temperature co-firing (LTCC), more stringent requirements are being placed on microwave dielectric materials: low dielectric constant, low loss, near-zero temperature coefficient of resonant frequency, and low sintering temperature. While traditional microwave dielectric ceramics offer stable performance, their high sintering temperatures and difficulty in co-firing with silver electrodes limit their application in multilayer devices. Therefore, developing novel microwave dielectric ceramics that combine excellent dielectric properties with low-temperature sintering characteristics has become a research hotspot in the field of functional ceramics. In recent years, molybdate ceramics have attracted widespread attention due to their advantages such as low sintering temperature and environmental friendliness. Among them, NaSrYbMo3O... 12 The ceramic has been confirmed to have a tetragonal scheelite structure, exhibiting good overall dielectric properties. e r =10.14, Q • f =30,487GHz, t f =-20.55ppm / ℃), and possesses good co-firing compatibility with silver electrodes, meeting the application conditions of LTCC technology. However, its quality factor ( Q·f ) and temperature coefficient of resonant frequency ( t f It is still difficult to meet the needs of high-performance microwave devices and needs further optimization.
[0003] Ion doping is an effective and widely used method for optimizing the dielectric properties of ceramics. Numerous successful studies have been conducted in ceramic systems containing (MoO4) groups. For example, ion doping with Sn... 4+ and Ti 4+ Ions in Ce2Zr3(MoO4)9 ceramics ( e r =10.69, Q • f =19,062GHz, t f Substituted Zr in (=-1.29ppm / ℃) 4+ Ions, can be Q • f The values significantly increased to 72,930 GHz and 84,200 GHz, and remained stable. t fThe values did not deteriorate significantly (-7.54 ppm / ℃ and -7.86 ppm / ℃). Notably, scheelite-type AMoO4 ceramics, similar to perovskite-structured ABO3 compounds, exhibit adaptive structural characteristics. In scheelite-type AMoO4 ceramics, both A and Mo sites can be substituted by various ions while maintaining structural stability. Therefore, the doping flexibility of the scheelite structure provides a broad modification window for studying the relationship between crystal structure and dielectric properties. In a similar CaMoO4 ceramic system, using Cd... 2+ Ion substitution of Ca 2+ The ions were used to obtain Ca at low temperatures (900-1075℃). 1-x Cd x The excellent properties of MoO4 ceramics ( e r =8-10, Q • f =46,000-53,000GHz, t f =-22--57ppm / ℃). Furthermore, by substituting the Ca site with Li and Ln(Sm, Nd) elements, a temperature-stable [(Li 0.5 Ln 0.5 ) 0.2 Ca 0.8 MoO4 ceramics possess excellent microwave dielectric properties. e r =10.6-11, Q • f =18400-24500GHz, t f =-7.1-+6.9ppm / ℃) and a relatively low sintering temperature (800-900℃). Although NaSrYbMo3O 12 Ceramics possess good basic dielectric properties, but their A-site ions (Na+) have not yet been observed. + 、Sr 2+ Reports have been made on co-doping to systematically regulate microwave dielectric properties. Based on the doping flexibility of scheelite structures, this invention uses K... + Partially replaces Na + Ba 2+ Partially replaces Sr 2+ Construct Na 1-x K x Sr 1-x Ba x YbMo3O 12Solid solution systems aim to systematically optimize their crystal structure, sintering characteristics, and dielectric properties through ionic synergistic effects, thereby obtaining novel microwave dielectric ceramics more suitable for high-frequency communication device applications. In summary, providing a molybdate microwave dielectric ceramic material with higher quality factor, better temperature stability, and lower-temperature sintering characteristics is of significant importance in this field. Summary of the Invention
[0004] This invention addresses the problems existing in the prior art by adjusting the molar ratio of four elements, Na, K, Sr, and Ba, to (1- x ): x :(1- x ): x NaSrYbMo3O 12 Na in ceramics + and Sr 2+ Perform ion doping to provide K + Ba 2+ Co-doped scheelite-molybdenum-based microwave dielectric ceramics and their preparation method. The prepared ceramics have the following formula: Na 1-x K x Sr 1-x Ba x YbMo3O 12 , where 0.04≤ x ≤0.10, crystal structure belongs to the tetragonal crystal system. I 41 / a Space group, sintering temperature 850-950℃, dielectric constant e r =9.32-10.64, quality factor Q • f =96,242-123,076 GHz, temperature coefficient of resonant frequency t f =-15.27--6.73ppm / ℃.
[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: A microwave dielectric ceramic based on scheelite and co-doped with A-site ions, wherein the compositional formula of the microwave dielectric ceramic is Na 1-x K x Sr 1-x Ba x YbMo3O 12 , where 0.04≤ x ≤0.10.
[0006] Furthermore, the relative permittivity of the ceramic e r =9.32-10.64, quality factor Q• f =96,242-123,076 GHz, temperature coefficient of resonant frequency t f =-15.27--6.73ppm / ℃.
[0007] A method for preparing A-site ion co-doping controlled scheelite molybdenum-based microwave dielectric ceramics includes the following preparation steps: (1) According to Na 1-x K x Sr 1-x Ba x YbMo3O 12 Weigh out Na2CO3, K2CO3, SrCO3, BaCO3, Yb2O3, and MoO3 according to stoichiometric ratio. Use ZrO2 grinding balls as the grinding medium and anhydrous ethanol as the dispersant. Mix the materials in a drum ball mill for 10-24 hours. Place the ball-milled slurry in a drying oven to dry. (2) Grind and sieve the dried powder from step (1), and then place the powder in a corundum crucible for pre-firing to obtain highly active ceramic powder; (3) Add the pre-fired high-activity ceramic powder from step (2) to ZrO2 grinding balls and anhydrous ethanol for ball milling again. The ball milling time is 10-24 hours. The slurry after ball milling is dried in a drying oven and sieved. (4) Add a binder to the powder after sieving in step (3) and granulate it to obtain a powder with good flowability; place the powder in a steel mold and form it by a tablet press to obtain a pellet; (5) Place the blank obtained in step (4) in a muffle furnace and sinter at high temperature to remove the binder, thereby obtaining a ceramic blank; (6) Place the ceramic blank obtained in step (5) in a box-type resistance furnace and sinter at 850-950℃ for 4-10 hours. After sintering is completed, allow it to cool down naturally.
[0008] Furthermore, in step (1), the mass ratio of powder, ZrO2 grinding ball and anhydrous ethanol is 10:100:15.
[0009] Furthermore, in step (2), the powder is ground through an 80-mesh sieve, the pre-firing temperature is 600-700℃, and the pre-firing time is 2-6 hours.
[0010] Furthermore, in step (3), the mass ratio of active ceramic powder, ZrO2 grinding balls and anhydrous ethanol during the secondary ball milling is 10:100:15.
[0011] Furthermore, the binder mentioned in step (4) is high-purity paraffin wax, and its addition amount is 10-14% of the powder mass. The pressure applied by the tablet press is 300MPa, and the green body is cylindrical with a diameter of 10mm and a height of 6mm.
[0012] Furthermore, in step (5), the high-temperature glue removal temperature is 500℃ and the heat preservation time is 3 hours.
[0013] Beneficial effects: This invention utilizes A-site ion co-doping to control the low dielectric constant (9.32-10.64) of scheelite-molybdenum-based microwave dielectric ceramics, thereby achieving high-speed signal transmission. + Ba 2+ Ion pairs NaSrYbMo3O 12 Na in ceramics + and Sr 2+ Through coordinated control, scheelite-molybdenum-based microwave dielectric ceramics with single-phase high quality factors (96,242-123,076 GHz) and excellent resonant frequency temperature coefficients (-15.27 to 6.73 ppm / ℃) were obtained to meet signal quality requirements. Furthermore, this invention can be prepared using a solid-state reaction sintering method, which is simple, effective, and easy to mass-produce, thus facilitating further industrialization. Attached Figure Description
[0014] Figure 1 Na is the present invention 1-x K x Sr 1-x Ba x YbMo3O 12 Microwave dielectric properties of ceramic examples 1-4; Figure 2 Na is the present invention 1-x K x Sr 1-x Ba x YbMo3O 12 XRD patterns of ceramic examples 1-4. Detailed Implementation
[0015] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.
[0016] Example 1 (1) According to Na 1-x K x Sr 1-x Ba x YbMo3O 12 ( x=0.04) Weigh out 2.0020g of Na2CO3, 0.1088g of K2CO3, 5.6053g of SrCO3, 0.3106g of BaCO3, 7.7234g of Yb2O3, and 16.9951g of MoO3 in stoichiometric ratio. Use ZrO2 grinding balls as the grinding medium and anhydrous ethanol as the dispersant. Mix the materials in a drum ball mill for 10 hours. The slurry after ball milling is then dried in a drying oven.
[0017] (2) Grind the dried powder from step (1) and pass it through an 80-mesh sieve. Then place the powder in a corundum crucible and pre-fire it in a box-type resistance furnace at 600°C for 6 hours to obtain highly active ceramic powder.
[0018] (3) The high-activity ceramic powder after pre-calcination in step (2) is added to ZrO2 grinding balls and anhydrous ethanol for ball milling again. The ball milling time is 10 hours. The slurry after ball milling is placed in a drying oven to dry and pass through an 80-mesh sieve.
[0019] (4) Add 10wt.% paraffin wax as a binder to the powder after sieving in step (3) and granulate to obtain a powder with good flowability. Place the powder in a steel mold and apply a pressure of 300MPa through a tablet press to obtain a cylindrical green body with a diameter of 10mm and a height of 6mm.
[0020] (5) Place the green body obtained in step (4) in a muffle furnace and hold it at 500°C for 3 hours to remove the paraffin wax used for bonding.
[0021] (6) Place the ceramic green body obtained in step (5) in a box-type resistance furnace and sinter at 950°C for 4 hours.
[0022] In step (1), the mass ratio of powder, ZrO2 grinding ball and anhydrous ethanol is 10:100:15.
[0023] In step (3), the mass ratio of active ceramic powder, ZrO2 grinding balls and anhydrous ethanol during the secondary ball milling is 10:100:15.
[0024] Example 2 (1) According to Na 1-x K x Sr 1-x Ba x YbMo3O 12 ( x=0.06) Weigh out 1.9569g of Na2CO3, 0.1629g of K2CO3, 5.4791g of SrCO3, 0.4651g of BaCO3, 7.7101g of Yb2O3, and 16.9659g of MoO3 in stoichiometric proportions. Use ZrO2 grinding balls as the grinding media and anhydrous ethanol as the dispersant. Mix the materials in a drum ball mill for 16 hours. The slurry after ball milling is then dried in a drying oven.
[0025] (2) Grind the dried powder from step (1) and pass it through an 80-mesh sieve. Then place the powder in an alumina crucible and pre-fire it in a box-type resistance furnace at 650°C for 4 hours to obtain highly active ceramic powder.
[0026] (3) The high-activity ceramic powder after pre-calcination in step (2) is added to ZrO2 grinding balls and anhydrous ethanol for ball milling again. The ball milling time is 16 hours. The slurry after ball milling is placed in a drying oven to dry and pass through an 80-mesh sieve.
[0027] (4) Add 11wt.% paraffin wax as a binder to the powder after sieving in step (3) and granulate to obtain a powder with good flowability. Place the powder in a steel mold and apply a pressure of 300MPa through a tablet press to obtain a cylindrical green body with a diameter of 10mm and a height of 6mm.
[0028] (5) Place the green body obtained in step (4) in a muffle furnace and hold it at 500°C for 3 hours to remove the paraffin wax used for bonding.
[0029] (6) Place the ceramic green body obtained in step (5) in a box-type resistance furnace and sinter at 925°C for 6 hours.
[0030] In step (1), the mass ratio of powder, ZrO2 grinding ball and anhydrous ethanol is 10:100:15.
[0031] In step (3), the mass ratio of active ceramic powder, ZrO2 grinding balls and anhydrous ethanol during the secondary ball milling is 10:100:15.
[0032] Example 3 (1) According to Na 1-x K x Sr 1-x Ba x YbMo3O 12 ( x=0.08) Weigh out 1.9120g of Na2CO3, 0.2168g of K2CO3, 5.3533g of SrCO3, 0.6191g of BaCO3, 7.6969g of Yb2O3, and 16.9369g of MoO3 in stoichiometric ratio. Use ZrO2 grinding balls as the grinding medium and anhydrous ethanol as the dispersant. Mix the materials in a drum ball mill for 20 hours. The slurry after ball milling is then dried in a drying oven.
[0033] (2) Grind the dried powder from step (1) and pass it through an 80-mesh sieve. Then place the powder in a corundum crucible and pre-fire it in a box-type resistance furnace at 675°C for 2 hours to obtain highly active ceramic powder.
[0034] (3) Add the high-activity ceramic powder after pre-calcination in step (2) to ZrO2 grinding balls and anhydrous ethanol for ball milling again. The ball milling time is 20 hours. The slurry after ball milling is placed in a drying oven to dry and pass through an 80-mesh sieve.
[0035] (4) Add 12wt.% paraffin wax as a binder to the powder after sieving in step (3) and granulate to obtain a powder with good flowability. Place the powder in a steel mold and apply a pressure of 300MPa through a tablet press to obtain a cylindrical green body with a diameter of 10mm and a height of 6mm.
[0036] (5) Place the green body obtained in step (4) in a muffle furnace and hold it at 500°C for 3 hours to remove the paraffin wax used for bonding.
[0037] (6) Place the ceramic green body obtained in step (5) in a box-type resistance furnace and sinter at 875°C for 8 hours.
[0038] In step (1), the mass ratio of powder, ZrO2 grinding ball and anhydrous ethanol is 10:100:15.
[0039] In step (3), the mass ratio of active ceramic powder, ZrO2 grinding balls and anhydrous ethanol during the secondary ball milling is 10:100:15.
[0040] Example 4 (1) According to Na 1-x K x Sr 1-x Ba x YbMo3O 12 ( x=0.10) Weigh out 1.8673g of Na2CO3, 0.2706g of K2CO3, 5.2280g of SrCO3, 0.7726g of BaCO3, 7.6838g of Yb2O3, and 16.9079g of MoO3 in stoichiometric ratio. Use ZrO2 grinding balls as the grinding medium and anhydrous ethanol as the dispersant, and mix them in a drum ball mill for 24 hours. The slurry after ball milling is then dried in a drying oven.
[0041] (2) Grind the dried powder from step (1) and pass it through an 80-mesh sieve. Then place the powder in a corundum crucible and pre-fire it in a box-type resistance furnace at 700°C for 2 hours to obtain highly active ceramic powder.
[0042] (3) The high-activity ceramic powder after pre-calcination in step (2) is added to ZrO2 grinding balls and anhydrous ethanol for ball milling again. The ball milling time is 24 hours. The slurry after ball milling is placed in a drying oven to dry and pass through an 80-mesh sieve.
[0043] (4) Add 14wt.% paraffin wax as a binder to the powder after sieving in step (3) and granulate to obtain a powder with good flowability. Place the powder in a steel mold and apply a pressure of 300MPa through a tablet press to obtain a cylindrical green body with a diameter of 10mm and a height of 6mm.
[0044] (5) Place the green body obtained in step (4) in a muffle furnace and hold it at 500°C for 3 hours to remove the paraffin wax used for bonding.
[0045] (6) Place the ceramic green body obtained in step (5) in a box-type resistance furnace and sinter at 850°C for 10 hours.
[0046] In step (1), the mass ratio of powder, ZrO2 grinding ball and anhydrous ethanol is 10:100:15.
[0047] In step (3), the mass ratio of active ceramic powder, ZrO2 grinding balls and anhydrous ethanol during the secondary ball milling is 10:100:15.
[0048] Comparative Example 1 In this comparative example, except that K and Ba were not used to modify Na and Sr, the raw materials and process steps were the same as in Example 4.
[0049] (1) According to NaSrYbMo3O 12 The stoichiometric ratios of Na2CO3 (2.0926 g), SrCO3 (5.8589 g), Yb2O3 (7.7500 g), and MoO3 (17.0537 g) were weighed out. The mixture was then mixed in a drum ball mill for 24 hours using ZrO2 grinding balls as the milling medium and anhydrous ethanol as the dispersant. The milled slurry was then dried in a drying oven.
[0050] (2) Grind the dried powder from step (1) and pass it through an 80-mesh sieve. Then place the powder in a corundum crucible and pre-fire it in a box-type resistance furnace at 700°C for 2 hours to obtain highly active ceramic powder.
[0051] (3) The high-activity ceramic powder after pre-calcination in step (2) is added to ZrO2 grinding balls and anhydrous ethanol for ball milling again. The ball milling time is 24 hours. The slurry after ball milling is placed in a drying oven to dry and pass through an 80-mesh sieve.
[0052] (4) Add 14wt.% paraffin wax as a binder to the powder after sieving in step (3) and granulate to obtain a powder with good flowability. Place the powder in a steel mold and apply a pressure of 300MPa through a tablet press to obtain a cylindrical green body with a diameter of 10mm and a height of 6mm.
[0053] (5) Place the green body obtained in step (4) in a muffle furnace and hold it at 500°C for 3 hours to remove the paraffin wax used for bonding.
[0054] (6) Place the ceramic green body obtained in step (5) in a box-type resistance furnace and sinter at 850°C for 10 hours.
[0055] In step (1), the mass ratio of powder, ZrO2 grinding ball and anhydrous ethanol is 10:100:15.
[0056] In step (3), the mass ratio of active ceramic powder, ZrO2 grinding balls and anhydrous ethanol during the secondary ball milling is 10:100:15.
[0057] Comparative Example 2 This comparative example, except for using only K + Partially replaces Na + Apart from doping modification, the other raw materials and process steps are the same as in Example 4.
[0058] (1) According to Na 1-x K x SrYbMo3O 12 ( x =0.10) Weigh out 1.8794g of Na2CO3, 0.2723g of K2CO3, 5.8466g of SrCO3, 7.7337g of Yb2O3, and 17.0178g of MoO3 in stoichiometric ratio. Use ZrO2 grinding balls as the grinding medium and anhydrous ethanol as the dispersant. Mix the materials in a drum ball mill for 24 hours. The slurry after ball milling is then dried in a drying oven.
[0059] (2) Grind the dried powder from step (1) and pass it through an 80-mesh sieve. Then place the powder in a corundum crucible and pre-fire it in a box-type resistance furnace at 700°C for 2 hours to obtain highly active ceramic powder.
[0060] (3) The high-activity ceramic powder after pre-calcination in step (2) is added to ZrO2 grinding balls and anhydrous ethanol for ball milling again. The ball milling time is 24 hours. The slurry after ball milling is placed in a drying oven to dry and pass through an 80-mesh sieve.
[0061] (4) Add 14wt.% paraffin wax as a binder to the powder after sieving in step (3) and granulate to obtain a powder with good flowability. Place the powder in a steel mold and apply a pressure of 300MPa through a tablet press to obtain a cylindrical green body with a diameter of 10mm and a height of 6mm.
[0062] (5) Place the green body obtained in step (4) in a muffle furnace and hold it at 500°C for 3 hours to remove the paraffin wax used for bonding.
[0063] (6) Place the ceramic green body obtained in step (5) in a box-type resistance furnace and sinter at 850°C for 10 hours.
[0064] In step (1), the mass ratio of powder, ZrO2 grinding ball and anhydrous ethanol is 10:100:15.
[0065] In step (3), the mass ratio of active ceramic powder, ZrO2 grinding balls and anhydrous ethanol during the secondary ball milling is 10:100:15.
[0066] Comparative Example 3 In this comparative example, except that Ba was used to replace part of the Sr for doping modification, the other raw materials and process steps were the same as in Example 4.
[0067] (1) According to NaSr 1-x Ba x YbMo3O 12 ( x =0.10) Weigh out 2.0791g of Na2CO3, 5.2389g of SrCO3, 0.7742g of BaCO3, 7.6999g of Yb2O3, and 16.9434g of MoO3 in stoichiometric ratio. Use ZrO2 grinding balls as the grinding medium and anhydrous ethanol as the dispersant. Mix the materials in a drum ball mill for 24 hours. Place the ball-milled slurry in a drying oven to dry.
[0068] (2) Grind the dried powder from step (1) and pass it through an 80-mesh sieve. Then place the powder in a corundum crucible and pre-fire it in a box-type resistance furnace at 700°C for 2 hours to obtain active ceramic powder.
[0069] (3) Add the pre-fired active ceramic powder from step (2) to ZrO2 grinding balls and anhydrous ethanol for ball milling again. The ball milling time is 24 hours. The slurry after ball milling is dried in a drying oven and passed through an 80-mesh sieve.
[0070] (4) Add 14wt.% paraffin wax as a binder to the powder after sieving in step (3) and granulate to obtain a powder with good flowability. Place the powder in a steel mold and apply a pressure of 300MPa through a tablet press to obtain a cylindrical green body with a diameter of 10mm and a height of 6mm.
[0071] (5) Place the green body obtained in step (4) in a muffle furnace and hold it at 500°C for 3 hours to remove the paraffin wax used for bonding.
[0072] (6) Place the ceramic green body obtained in step (5) in a box-type resistance furnace and sinter at 850°C for 10 hours.
[0073] In step (1), the mass ratio of powder, ZrO2 grinding ball and anhydrous ethanol is 10:100:15.
[0074] In step (3), the mass ratio of active ceramic powder, ZrO2 grinding balls and anhydrous ethanol during the secondary ball milling is 10:100:15.
[0075] Performance testing Table 1 shows the microwave dielectric properties of Examples 1-4 and Comparative Examples 1-3, evaluated using the cylindrical dielectric resonator method in conjunction with a vector network analyzer. The specific testing procedures, methods, and conditions are as follows: The tests were conducted using a vector network analyzer (Keysight E5071C) and a matching cylindrical resonator fixture. The ceramic samples to be tested were precisely machined into a cylindrical shape, with the diameter-to-height ratio controlled at approximately 2.0. Dielectric constant... e r The measurement was performed using the Hakki-Coleman method, by exciting and identifying TE at 25°C. 011 Resonant mode obtained. Quality factor. Q‧f The test used the closed-cavity method, measuring TE at 25°C. 01δ The mode is obtained. As for the temperature coefficient of the resonant frequency... t f Then, by monitoring the sample at TE 011 The resonant frequency was measured at 25°C and 85°C during the modeling process.
[0076] Table 1. Performance test results of the examples and comparative examples. From the data in Table 1, we can see the dielectric constants of all experimental groups. All values are within the range of 9.32-10.64, maintaining a low dielectric constant, which is beneficial for high-speed signal transmission. Meanwhile, the embodiments exhibit high... Q‧f The value (96,242-123,076 GHz) is significantly higher than that of Comparative Example 1 (30,487 GHz), Comparative Example 2 (52,000 GHz), and Comparative Example 3 (48,000 GHz), proving that K + and Ba 2+ Co-doping produces a synergistic effect, significantly improving the quality factor and reducing dielectric loss. Example: Temperature coefficient of resonant frequency. The values (-15.27 ppm / ℃ to -6.73 ppm / ℃) are closer to zero than those of Comparative Example 1 (-20.55 ppm / ℃), Comparative Example 2 (-28.50 ppm / ℃), and Comparative Example 3 (-27.00 ppm / ℃), indicating that co-doping effectively improves temperature stability. This demonstrates that the overall performance of Comparative Examples 1-3 is significantly weaker than that of Example 4, indicating that single-ion doping cannot achieve synergistic optimization through ion co-doping, and that co-doping comprehensively improves microwave dielectric properties.
[0077] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
Claims
1. A type of A-site ion co-doped scheelite-molybdenum-based microwave dielectric ceramic, characterized in that, The chemical formula for the microwave dielectric ceramic is Na. 1-x K x Sr 1-x Ba x YbMo3O 12 , where 0.04≤ x ≤0.
10.
2. The A-site ion co-doped scheelite-molybdenum-based microwave dielectric ceramic according to claim 1, characterized in that, The relative permittivity of the ceramic ε r =9.32-10.64, quality factor Q • f =96,242-123,076 GHz, temperature coefficient of resonant frequency τ f =-15.27--6.73ppm / °C.
3. A method for preparing A-site ion co-doping controlled scheelite-molybdenum-based microwave dielectric ceramic as described in claim 1, characterized in that, The preparation steps include the following: (1) According to Na 1-x K x Sr 1-x Ba x YbMo3O 12 Weigh out Na2CO3, K2CO3, SrCO3, BaCO3, Yb2O3, and MoO3 according to stoichiometric ratio, and mix them in a ball mill for 10-24 hours using ZrO2 balls as the ball milling medium and anhydrous ethanol as the dispersant. Then, dry the slurry after ball milling. (2) Grind and sieve the dried powder from step (1), and then pre-fire the powder to obtain highly active ceramic powder; (3) Add the pre-fired high-activity ceramic powder from step (2) to ZrO2 balls and anhydrous ethanol for ball milling again. The ball milling time is 10-24 hours. The slurry after ball milling is dried and sieved. (4) Add a binder to the powder after sieving in step (3) and granulate it to obtain a powder with good flowability; place the powder in a steel mold and form it by a tablet press to obtain a blank. (5) The blank obtained in step (4) is debonded at high temperature in a muffle furnace to obtain a ceramic blank; (6) Place the ceramic blank obtained in step (5) in a box-type resistance furnace and sinter at 850-950℃ for 4-10 hours. After sintering, allow it to cool down naturally.
4. The method for preparing A-site ion co-doping controlled scheelite molybdenum-based microwave dielectric ceramics according to claim 3, characterized in that, In step (1), the mass ratio of powder, ZrO2 grinding ball and anhydrous ethanol is 10:100:
15.
5. The method for preparing A-site ion co-doping controlled scheelite molybdenum-based microwave dielectric ceramics according to claim 3, characterized in that, Step (2) Grind the powder through an 80-mesh sieve, pre-fire at 600-700℃ for 2-6 hours.
6. The method for preparing A-site ion co-doping controlled scheelite molybdenum-based microwave dielectric ceramics according to claim 3, characterized in that, In step (3), the mass ratio of active ceramic powder, ZrO2 balls and anhydrous ethanol during the second ball milling is 10:100:
15.
7. The method for preparing A-site ion co-doping controlled scheelite-molybdenum-based microwave dielectric ceramics according to claim 3, characterized in that, The binder mentioned in step (4) is paraffin wax, and its addition amount is 10-14% of the powder mass. The pressure applied by the tablet press is 300MPa, and the blank is cylindrical with a diameter of 10mm and a height of 6mm.
8. The method for preparing A-site ion co-doping controlled scheelite molybdenum-based microwave dielectric ceramics according to claim 3, characterized in that, In step (5), the high-temperature adhesive removal temperature is 500℃, and the heat preservation time is 3 hours.