Magnesium tantalate-based microwave dielectric material and preparation method thereof

Abstract

The invention relates to a magnesium tantalate-based microwave dielectric material and a preparation method thereof. The magnesium tantalate-based microwave dielectric material comprises the following chemical components: Mg < 1 / 2 > A < 11 / 2 > Ta2O6, Mg < 1 / 3 > A < 11 / 3 > A < 21 / 3 > Ta2O6, Mg < 0.25 > A < 1 > < 0.25 > A < 2 > < 0.25 > A < 3 > < 0.25 > Ta2O6, Mg < 0.2 > A < 1 > < 0.2 > A < 2 > < 0.2 > A < 3 > < 0.2 > A < 4 > < 0.2 > Ta2O6 or Mg < 1 / 6 > A < 11 / 6 > A < 21 / 6 > A < 31 / 6 > A < 41 / 6 > A < 51 / 6 > Ta2O6. Wherein A1, A2, A3, A4 and A5 are independently selected from five of Co, Ni, Zn, Mn, Cu, Ca and Sr.

Description

Technical Field

[0001] The invention relates to a magnesium tantalate-based microwave dielectric material and a preparation method thereof, and belongs to the field of material preparation. Background Art

[0002] Microwave dielectric ceramics are one of the important components of passive devices, mainly used as filters, resonators, radio frequency antennas, discriminators in electronic countermeasures, navigation, radar, home satellite live TV receivers and handheld mobile phones. 2 O 6 The ceramic system has excellent microwave dielectric properties, among which MgTa with a triple rutile structure 2 O 6 Ceramics have a suitable dielectric constant (ε r ~30) and low dielectric loss (Q·f~60000GHz), making it an excellent candidate material for high-frequency modern communication technology.

[0003] But MgTa 2 O 6 Ceramics have the problems of high sintering temperature (~1550℃) and poor temperature stability (~54ppm / ℃) (J Am Ceram Soc. 2018; 101:3026–3031.), which limits their application in microwave circuits and devices. In the traditional preparation process, sintering aids are usually added to reduce the sintering temperature of ceramics, such as low-melting oxides, fluorides and glasses. This has the advantages of low cost and simple process compared with sol-gel and hydrothermal preparation processes. However, the addition of sintering aids makes the preparation of ceramics more complicated, and sometimes the problem of volatilization needs to be considered, which makes it difficult to accurately control the content of sintering aids. At the same time, the mechanism of the influence on temperature stability is relatively complicated. Therefore, it is very important to find a method that can both reduce the sintering temperature and improve the temperature stability. Summary of the invention

[0004] To this end, the present invention provides a magnesium tantalate-based microwave dielectric material and a preparation method thereof.

[0005] In one aspect, the present invention provides a magnesium tantalate-based microwave dielectric material, wherein the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 1 / 2 A1 1 / 2 Ta 2 O 6 Mg 1 / 3 A1 1 / 3 A2 1 / 3 Ta 2 O 6 Mg 0.25 A1 0.25 A2 0.25 A3 0.25 Ta2 O 6 Mg 0.2 A1 0.2 A2 0.2 A3 0.2 A4 0.2 Ta 2 O 6 or Mg 1 / 6 A1 1 / 6 A2 1 / 6 A3 1 / 6 A4 1 / 6 A5 1 / 6 Ta 2 O 6 ; Wherein A1, A2, A3, A4, A5 are independently selected from five of Co, Ni, Zn, Mn, Cu, Ca, and Sr.

[0006] In the present invention, a single-phase solid solution formed by at least one cation in an equimolar ratio is constructed at the Mg position of the magnesium tantalate crystal. Preferably, a single-phase solid solution formed by 4 or more cations in an equimolar ratio is constructed at the Mg position of the magnesium tantalate crystal. The obtained ceramic has four core effects, namely, high mixing entropy effect, lattice distortion effect, hysteresis diffusion effect and "cocktail effect", which will be beneficial to improving the performance of the ceramic. The high mixing entropy effect is beneficial to the formation of a single-phase solid solution (such as Figure 1 As shown, the ceramics in the embodiments all maintain a single-phase structure without other heterogeneous peaks or impurity peaks). The lattice distortion effect increases structural defects, which can serve as fast diffusion channels during the sintering process, promote the sintering reaction, and reduce the sintering temperature. 0.25 Co 0.25 Ni 0.25 Zn 0.25 Ta 2 O 6 Ceramics and Mg 0.2 Co 0.2 Ni 0.2 Zn 0.2 Mn 0.2 Ta 2 O 6 The sintering temperature of the densest point of ceramics is compared with MgTa 2 O 6 In addition, the lattice distortion caused by elements with different atomic radii and electronegativity weakens the interaction between atoms and reduces the coupling relationship between material performance and temperature. On the one hand, the Q·f value of the material remains stable in a wide temperature range (for example, 1250-1550℃, 300℃ temperature range), and on the other hand, the resonant frequency temperature coefficient of the ceramic is improved (49-51ppm / ℃ is improved to 36-46ppm / ℃), which is beneficial to its practical application.

[0007] Preferably, the Q·f value of the magnesium tantalate-based microwave dielectric material is 14100-85500 GHz, the relative dielectric constant is 17.2-30.1, and the resonant frequency temperature coefficient is 34-46 ppm / °C; preferably, the Q·f value of the magnesium tantalate-based microwave dielectric material is 22900-82900 GHz, the relative dielectric constant is 26.6-30.1, and the resonant frequency temperature coefficient is 36-46 ppm / °C.

[0008] In another aspect, the present invention provides a method for preparing a magnesium tantalate-based microwave dielectric material, comprising: (1) Combine MgO and Ta 2 O 5 , A1 source, A2 source, A3 source, A4 source and A5 source are prepared and mixed according to the chemical composition of the magnesium tantalate-based microwave dielectric material to obtain a raw material powder; (2) calcining the obtained raw material powder to obtain ceramic powder; (3) The obtained ceramic powder is made into a green body, and then sintered to obtain the magnesium tantalate-based microwave dielectric material.

[0009] The present invention uses MgO, Ta 2 O 5 and A source as raw materials to prepare magnesium tantalate-based microwave dielectric material Mg 0.25 A1 0.25 A2 0.25 A3 0.25 Ta 2 O 6 and Mg 0.2 A1 0.2 A2 0.2 A3 0.2 A4 0.2 Ta 2 O 6 In the present invention, the ceramic system has a simple preparation process, and the sintering temperature of the densest point is lower than that of pure MgTa. 2 O 6 The ceramic can be significantly reduced, and at the same time, it can maintain a stable Q·f value in a wide sintering temperature range, and reduce the temperature coefficient of the resonant frequency, thereby improving the comprehensive performance of the ceramic and expanding the MgTa 2 O 6 The practical application of ceramics is of great significance.

[0010] Preferably, in step (1), a synthesis aid is also added to the raw material powder; the synthesis aid includes B 2 O 3 、ZnO、WO 3 、Al 2 O 3 , MgO and SnO 2At least one of the following: the amount of the synthesis aid added is 0 to 0.6 wt. % of the total mass of the raw material powder, preferably 0.2 wt. %.

[0011] Preferably, in step (1), the mixing method is ball milling; the parameters of the ball milling mixing include: using deionized water as the solvent, the ball milling speed is 440-460 rpm, and the ball milling time is ≥1 hour; preferably, the ball milling mixing is followed by drying, and the drying temperature is 100-130°C, more preferably 130°C.

[0012] Preferably, in step (2), the calcination temperature is 1000-1200° C. and the calcination time is not less than 8 hours.

[0013] Preferably, in step (3), the green body is formed by dry pressing; the pressure of the dry pressing is 1 to 3 MPa, and the time is 0.5 to 1 minute.

[0014] Preferably, before dry pressing, the ceramic powder is subjected to secondary ball milling and secondary drying, and then a binder is added to granulate to obtain granulated powder; preferably, the particle size of the granulated powder is 1 to 10 μm; The parameters of the secondary ball milling mixing include: using deionized water as a solvent, 5wt.% anhydrous ethanol as a grinding aid, a ball milling speed of 440 to 460 rpm, and a ball milling time of ≥1 hour; The temperature of the secondary drying is 100-130°C, more preferably 130°C; The binder is a 3% by mass polyvinyl alcohol solution; the ratio of the ceramic powder to the 3% by mass polyvinyl alcohol solution is (25-100) g and: 1 mL; Preferably, the granulation is followed by screening, wherein the screening is through a 40-60 mesh sieve.

[0015] Preferably, in step (3), the sintering temperature is 1200-1600° C.; the sintering holding time is 4-6 hours; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 1 / 2 A1 1 / 2 Ta 2 O 6 When the sintering temperature is 1300-1500°C; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 1 / 3 A1 1 / 3 A2 1 / 3 Ta 2 O 6 When the sintering temperature is 1300-1500°C; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 0.25 A1 0.25 A2 0.25 A3 0.25 Ta 2 O 6 When the sintering temperature is 1200-1600°C; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 0.2 A1 0.2 A2 0.2 A3 0.2 A4 0.2 Ta 2 O 6 When the sintering temperature is 1300-1600°C; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 1 / 6 A1 1 / 6 A2 1 / 6 A3 1 / 6 A4 1 / 6 A5 1 / 6 Ta 2 O 6 When the sintering temperature is 1300-1500°C; Preferably, the sintering temperature rise system includes: firstly heating the temperature at a heating rate of 5°C / min to a temperature 100°C lower than the sintering temperature, and then heating the temperature at a heating rate of 1°C / min to the sintering temperature.

[0016] Beneficial effects of the present invention: 1. The ceramics prepared in the present invention have increased structural defects, which can serve as fast diffusion channels during the sintering process, promote the sintering reaction, and reduce the sintering temperature; 2. The lattice distortion effect of ceramics reduces the interatomic force and the coupling effect between material performance and temperature, making the Q·f value of the material stable over a wide temperature range, which is conducive to significantly improving the yield rate and reducing production costs in the subsequent industrialization process, and also improves the resonant frequency temperature coefficient of the material; 3. The method of the present invention has simple equipment, simple process, short sintering time, and MgTa 2 O 6 The A-site design of ceramics improves the overall performance of ceramics, and this idea is expected to be extended to other ceramic systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the XRD pattern of the microwave dielectric material powder raw material (calcined at 1100° C. for 8 h) obtained in Example 1-4; Figure 2XRD diagram of the microwave dielectric material powder raw material (calcined at 1100° C. for 8 h) obtained in Examples 4-7 and Comparative Example 1; Figure 3 Graph showing the relationship between the Q·f value and the sintering temperature of the microwave dielectric materials obtained in Examples 1-7 and Comparative Example 1. DETAILED DESCRIPTION

[0018] The present invention is further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0019] In order to solve the existing MgTa 2 O 6 The problem of high sintering temperature and high temperature coefficient of resonant frequency of ceramics is solved. The present invention provides a magnesium tantalate-based microwave dielectric material and a preparation method thereof.

[0020] In the present disclosure, the chemical composition of magnesium tantalate-based microwave dielectric materials includes five types: one is Mg 1 / 2 A1 1 / 2 Ta 2 O 6 , where A1 is one of Co, Ni, Zn, Mn, Cu, Ca, Sr. One is Mg 1 / 3 A1 1 / 3 A2 1 / 3 Ta 2 O 6 , where A1 and A2 are two non-repeating ones among Co, Ni, Zn, Mn, Cu, Ca, and Sr. One is Mg 0.25 A1 0.25 A2 0.25 A3 0.25 Ta 2 O 6 , where A1, A2, and A3 are three non-repeating ones among Co, Ni, Zn, Mn, Cu, Ca, and Sr. One is Mg 0.2 A1 0.2 A2 0.2 A3 0.2 A4 0.2 Ta 2 O 6 , where A1, A2, A3, and A4 are four non-repeating ones among Co, Ni, Zn, Mn, Cu, Ca, and Sr. One is Mg 1 / 6 A1 1 / 6 A2 1 / 6 A3 1 / 6 A4 1 / 6 A5 1 / 6 Ta 2 O 6, wherein A1, A2, A3, A4, and A5 are selected from five non-repeating types of Co, Ni, Zn, Mn, Cu, Ca, and Sr.

[0021] The following is an exemplary description of a method for preparing a magnesium tantalate-based microwave dielectric material.

[0022] Combine MgO, Ta 2 O 5 The A source and the B source were prepared according to the stoichiometric ratio, and 0.2 wt.% B was added 2 O 3 As a synthesis aid. Then, the raw material powder is obtained by ball milling, mixing and drying. For example, deionized water is used as a solvent, ball milling is performed for not less than 1 hour, and the raw material powder is obtained after drying at 130°C. The obtained raw material powder is calcined at 1100°C for not less than 8 hours, and the ceramic powder is obtained after natural cooling.

[0023] The ceramic powder is mixed and dried by secondary ball milling. Specifically, the ceramic powder and deionized water are uniformly mixed, ball milled for no less than 1 hour, and dried at 130° C. Then, a 3% by weight polyvinyl alcohol solution is added as a binder for granulation, and the ceramic green body is obtained by dry pressing after sieving.

[0024] The green body is sintered at 1300-1550° C., kept warm for 4 hours, and then cooled to room temperature in the furnace to prepare a magnesium tantalate-based microwave dielectric material.

[0025] The present invention prepares magnesium tantalate-based microwave dielectric material Mg 0.25 A1 0.25 A2 0.25 A3 0.25 Ta 2 O 6 (A1, A2, A3 are three non-repeating elements among Co, Ni, Zn, Mn, Cu, Ca, Sr) or Mg 0.2 A1 0.2 A2 0.2 A3 0.2 A4 0.2 Ta 2 O 6 (A1, A2, A3, A4 are four non-repeating elements among Co, Ni, Zn, Mn, Cu, Ca, Sr) or Mg 1 / 6 A1 1 / 6 A2 1 / 6 A3 1 / 6 A4 1 / 6 A5 1 / 6 Ta 2 O 6 (A1, A2, A3, A4, A5 are five non-repeating elements among Co, Ni, Zn, Mn, Cu, Ca, Sr), MgTa 2 O6 The A-position design of the ceramic can effectively reduce the sintering temperature of the densest point of the ceramic, and can maintain the stability of the Q·f value in a wide sintering temperature range, while reducing its resonant frequency temperature coefficient, and has excellent comprehensive dielectric properties.

[0026] In the present invention, the Q·f value of the magnesium tantalate-based microwave dielectric material is tested by using an Agilent E8362B network analyzer: 14100-85500 GHz. Moreover, the fluctuation range of the Q·f value of the magnesium tantalate-based microwave dielectric material of the present invention does not exceed 11%. Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 0.25 A1 0.25 A2 0.25 A3 0.25 Ta 2 O 6 When the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 0.2 A1 0.2 A2 0.2 A3 0.2 A4 0.2 Ta 2 O 6 When the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 1 / 6 A1 1 / 6 A2 1 / 6 A3 1 / 6 A4 1 / 6 A5 1 / 6 Ta 2 O 6 When the temperature of the magnesium tantalate-based microwave dielectric material is lower than 10%, the fluctuation amplitude of the magnesium tantalate-based microwave dielectric material does not exceed 10%.

[0027] In the present invention, the relative dielectric constant of the magnesium tantalate-based microwave dielectric material is tested by using an Agilent E8362B network analyzer: 17.2-30.1.

[0028] In the present invention, the resonant frequency temperature coefficient of the magnesium tantalate-based microwave dielectric material is tested by a resonant frequency tester and an incubator: 34-46 ppm / °C. The volume density of the magnesium tantalate-based microwave dielectric material is tested by the Archimedes drainage method, and the ratio of the volume density to the theoretical density is 74.8-98.1%.

[0029] The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0030] Example 1 The chemical formula of the magnesium tantalate-based microwave dielectric material in this embodiment 1 is Mg 0.25 Co 0.25 Ni 0.25 Zn 0.25 Ta 2 O 6 , follow these steps: Step (1): MgO, CoO, NiO, ZnO and Ta with a purity greater than 99% 2 O 5 The raw materials are based on Mg 0.25 Co 0.25 Ni 0.25 Zn 0.25 Ta 2 O 6 Weigh the ingredients and add 0.2% by mass of B 2 O 3 As a synthetic auxiliary (with H 3 BO 3 Add in the form of zirconium oxide balls), put into a nylon jar with zirconium oxide balls, pour in deionized water, the weight ratio of material: ball: water = 1:5:1.5, ball mill for no less than 1 hour, the speed is 451 rpm. After ball milling, put into an oven and dry at 130°C for 8 hours. Put the dried powder into an alumina crucible, calcine at 1100°C, keep warm for 8 hours, and cool naturally to obtain Mg 0.25 Co 0.25 Ni 0.25 Zn 0.25 Ta 2 O 6 Powder raw materials, XRD spectrum see Figure 1 ; Step (2): Place the powder obtained in step (1) into a nylon jar with zirconium oxide balls added, add deionized water, the weight ratio of which is material: ball: water = 1:5:1.5, and ball mill for 1 hour at a speed of 451 rpm. After ball milling, place it in an oven and dry it at 130°C for 8 hours. Add a polyvinyl alcohol solution with a mass concentration of 3% as a binder for granulation, and dry press it at a pressure of 1 MPa to obtain a 9.5 mm×5 mm ceramic green body; Step (3): Sintering the green body obtained in step (2) at 1200° C., 1250° C., 1300° C., 1350° C., 1400° C., 1450° C., 1500° C. and 1550° C. for 4 hours to prepare magnesium tantalate-based microwave dielectric material Mg 0.25 Co 0.25 Ni 0.25 Zn 0.25 Ta 2 O 6 , performance is shown in Table 1.

[0031] Example 2 The chemical formula of the magnesium tantalate-based microwave dielectric material in this embodiment 2 is Mg 0.25 Co 0.25 Zn 0.25 Mn 0.25 Ta 2 O 6 , follow these steps: Step (1): MgO, CoO, ZnO, MnO and Ta with a purity greater than 99% 2 O 5 The raw materials are based on Mg 0.25 Co 0.25 Zn 0.25 Mn 0.25 Ta 2 O 6 Weigh the ingredients and add 0.2% by mass of B 2 O 3 As a synthetic auxiliary (with H 3 BO 3 Add in the form of zirconium oxide balls), put into a nylon jar with zirconium oxide balls, pour in deionized water, the weight ratio of material: ball: water = 1:5:1.5, ball mill for no less than 1 hour, the speed is 451 rpm. After ball milling, put into an oven and dry at 130°C for 8 hours. Put the dried powder into an alumina crucible, calcine at 1100°C, keep warm for 8 hours, and cool naturally to obtain Mg 0.25 Co 0.25 Zn 0.25 Mn 0.25 Ta 2 O 6 Powder raw materials, XRD spectrum see Figure 1 ; Step (2): Place the powder obtained in step (1) into a nylon jar with zirconium oxide balls added, add deionized water, the weight ratio of which is material: ball: water = 1:5:1.5, and ball mill for 1 hour at a speed of 451 rpm. After ball milling, place it in an oven and dry it at 130°C for 8 hours. Add a polyvinyl alcohol solution with a mass concentration of 3% as a binder for granulation, and dry press it at a pressure of 1 MPa to obtain a 9.5 mm×5 mm ceramic green body; Step (3): Sintering the green body obtained in step (2) at 1300° C., 1350° C., 1400° C., 1450° C., 1500° C. and 1550° C. for 4 hours to prepare magnesium tantalate-based microwave dielectric material Mg 0.25 Co 0.25 Zn 0.25 Mn 0.25 Ta 2 O 6 , performance is shown in Table 1.

[0032] Example 3 The chemical formula of the magnesium tantalate-based microwave dielectric material in this embodiment 3 is Mg 0.25 Co 0.25 Ni 0.25 Mn 0.25 Ta 2 O 6 , follow these steps: Step (1): MgO, CoO, NiO, MnO and Ta with a purity greater than 99% 2 O 5 The raw materials are based on Mg 0.25 Co 0.25 Ni 0.25 Mn 0.25 Ta 2 O 6 Weigh the ingredients and add 0.2% by mass of B 2 O 3 As a synthetic auxiliary (with H 3 BO 3 Add in the form of zirconium oxide balls), put into a nylon jar with zirconium oxide balls, pour in deionized water, the weight ratio of material: ball: water = 1:5:1.5, ball mill for no less than 1 hour, the speed is 451 rpm. After ball milling, put into an oven and dry at 130°C for 8 hours. Put the dried powder into an alumina crucible, calcine at 1100°C, keep warm for 8 hours, and cool naturally to obtain Mg 0.25 Co 0.25 Ni 0.25 Mn 0.25 Ta 2 O 6 Powder raw materials, XRD spectrum see Figure 1 ; Step (2): Place the powder obtained in step (1) into a nylon jar with zirconium oxide balls added, add deionized water, the weight ratio of which is material: ball: water = 1:5:1.5, and ball mill for 1 hour at a speed of 451 rpm. After ball milling, place it in an oven and dry it at 130°C for 8 hours. Add a polyvinyl alcohol solution with a mass concentration of 3% as a binder for granulation, and dry press it at a pressure of 1 MPa to obtain a 9.5 mm×5 mm ceramic green body; Step (3): Sinter the green body obtained in step (2) at 1350°C, 1400°C, 1450°C, 1500°C, 1550°C and 1600°C for 4 hours to prepare magnesium tantalate-based microwave dielectric material Mg 0.25 Co 0.25 Ni 0.25 Mn 0.25 Ta 2 O 6 , performance is shown in Table 1.

[0033] Example 4 The chemical formula of the magnesium tantalate-based microwave dielectric material in this embodiment 4 is Mg 0.2 Co 0.2 Ni 0.2 Zn 0.2 Mn 0.2 Ta 2 O 6 , follow these steps: Step (1): MgO, CoO, NiO, ZnO, MnO and Ta with a purity greater than 99% 2 O 5 The raw materials are Mg 0.2 Co 0.2 Ni 0.2 Zn 0.2 Mn 0.2 Ta 2 O 6 Weigh the ingredients and add 0.2% by mass of B 2 O 3 As a synthetic auxiliary (with H 3 BO 3 Add in the form of zirconium oxide balls), put into a nylon jar with zirconium oxide balls, pour in deionized water, the weight ratio of material: ball: water = 1:5:1.5, ball mill for no less than 1 hour, the speed is 451 rpm. After ball milling, put into an oven and dry at 130°C for 8 hours. Put the dried powder into an alumina crucible, calcine at 1100°C, keep warm for 8 hours, and cool naturally to obtain Mg 0.2 Co 0.2 Ni 0.2 Zn 0.2 Mn 0.2 Ta 2 O6 Powder raw materials, XRD spectrum see Figure 1 ; Step (2): Place the powder obtained in step (1) into a nylon jar with zirconium oxide balls added, add deionized water, the weight ratio of which is material: ball: water = 1:5:1.5, and ball mill for 1 hour at a speed of 451 rpm. After ball milling, place it in an oven and dry it at 130°C for 8 hours. Add a polyvinyl alcohol solution with a mass concentration of 3% as a binder for granulation, and dry press it at a pressure of 1 MPa to obtain a 9.5 mm×5 mm ceramic green body; Step (3): Sintering the green body obtained in step (2) at 1300° C., 1350° C., 1400° C., 1450° C., 1500° C., 1550° C. and 1600° C. for 4 hours to prepare magnesium tantalate-based microwave dielectric material Mg 0.2 Co 0.2 Ni 0.2 Zn 0.2 Mn 0.2 Ta 2 O 6 , performance is shown in Table 1.

[0034] Example 5 The chemical formula of the magnesium tantalate-based microwave dielectric material in this embodiment 5 is Mg 0.5 Co 0.5 Ta 2 O 6 .

[0035] Example 6 The chemical formula of the magnesium tantalate-based microwave dielectric material in this embodiment 6 is Mg 1 / 3 Co 1 / 3 Ni 1 / 3 Ta 2 O 6 .

[0036] Example 7 The chemical formula of the magnesium tantalate-based microwave dielectric material in this embodiment 7 is Mg 1 / 6 Co 1 / 6 Ni 1 / 6 Zn 1 / 6 Mn 1 / 6 Ca 1 / 6 Ta 2 O 6 .

[0037] Comparative Example 1 The chemical formula of the magnesium tantalate-based microwave dielectric material in this comparative example 1 is MgTa 2 O 6 The preparation process thereof is shown in Example 1.

[0038] Table 1 shows the composition and properties of magnesium tantalate-based microwave dielectric materials:

[0039] Figure 3 The relationship between the Q·f value and the sintering temperature of the microwave dielectric material obtained in Examples 1-7 and Comparative Example 1 is shown. It can be seen that the sintering temperature of Comparative Example 1 changes by 50°C, and the Q·f value changes from tens of thousands to hundreds of thousands; Examples 5 and 6 are similar, and the high entropy ceramics obtained in the preferred Examples 1-4 and 7 of the present invention have obvious stability. The fluctuation range of Example 1 at 1200-1550°C does not exceed 11% (preferably, the fluctuation range at 1250-1550°C does not exceed 7%). The fluctuation range of Example 2 at 1350-1550°C does not exceed 8%. In Example 3, the fluctuation range at 1350-1600°C does not exceed 5%. In Example 4, the fluctuation range at 1300-1600°C does not exceed 5%. In Example 7, the fluctuation range at 1300-1500°C does not exceed 10% (preferably, the fluctuation range at 1300-1450°C does not exceed 7%). It should be noted that in the present invention, the fluctuation range = (maximum value - minimum value) ÷ 2 ÷ (average value of maximum value and minimum value).

Claims

1. A magnesium tantalate-based microwave dielectric material, It is characterized in that The chemical composition of the magnesium tantalate-based microwave dielectric material includes: Mg 1 / 2 A1 1 / 2 Ta 2 O 6 Mg 1 / 3 A1 1 / 3 A2 1 / 3 Ta 2 O 6 Mg 0.25 A1 0.25 A2 0.25 A3 0.25 Ta 2 O 6 Mg 0.2 A1 0.2 A2 0.2 A3 0.2 A4 0.2 Ta 2 O 6 or Mg 1 / 6 A1 1 / 6 A2 1 / 6 A3 1 / 6 A4 1 / 6 A5 1 / 6 Ta 2 O 6 ; Wherein A1, A2, A3, A4, A5 are independently selected from five of Co, Ni, Zn, Mn, Cu, Ca, and Sr.

2. The magnesium tantalate-based microwave dielectric material according to claim 1, It is characterized in that The magnesium tantalate-based microwave dielectric material has a Q·f value of 14100 to 85500 GHz, a relative dielectric constant of 17.2 to 30.1, and a resonant frequency temperature coefficient of 34 to 46 ppm / °C; Preferably, the magnesium tantalate-based microwave dielectric material has a Q·f value of 22900 to 82900 GHz, a relative dielectric constant of 26.6 to 30.1, and a resonant frequency temperature coefficient of 36 to 46 ppm / °C.

3. A method for preparing the magnesium tantalate-based microwave dielectric material as claimed in claim 1 or 2, It is characterized in that include: (1) Combine MgO and Ta 2 O 5 , A1 source, A2 source, A3 source, A4 source and A5 source are prepared and mixed according to the chemical composition of the magnesium tantalate-based microwave dielectric material to obtain a raw material powder; (2) calcining the obtained raw material powder to obtain ceramic powder; (3) The obtained ceramic powder is made into a green body, and then sintered to obtain the magnesium tantalate-based microwave dielectric material.

4. The preparation method according to claim 3, It is characterized in that In step (1), the synthesis aid includes B 2 O 3 、ZnO、WO 3 、Al 2 O 3 , MgO and SnO 2 At least one of the following: the amount of the synthesis aid added is 0 to 0.6 wt. % of the total mass of the raw material powder, preferably 0.2 wt. %.

5. The preparation method according to claim 3, It is characterized in that In step (1), the parameters of the ball milling mixing include: using deionized water as the solvent, the ball milling speed is 440 to 460 rpm, and the ball milling time is ≥ 1 hour; preferably, the ball milling mixing is then dried, and the drying temperature is 100 to 130° C., more preferably 130° C.

6. The preparation method according to claim 3, It is characterized in that In step (2), the calcination temperature is 1000-1200° C. and the calcination time is not less than 8 hours.

7. The preparation method according to claim 3, It is characterized in that In step (3), the green body is formed by dry pressing; the pressure of the dry pressing is 1 to 3 MPa, and the time is 0.5 to 1 minute.

8. The preparation method according to claim 7, It is characterized in that Before dry pressing, the ceramic powder is subjected to secondary ball milling and secondary drying, and then a binder is added to granulate to obtain granulated powder; preferably, the particle size of the granulated powder is 1 to 10 μm; The parameters of the secondary ball milling include: using deionized water as a solvent, 5wt.% anhydrous ethanol as a grinding aid, a ball milling speed of 440-460 rpm, and a ball milling time of ≥1 hour; The temperature of the secondary drying is 100-130°C, more preferably 130°C; The binder is a 3% by mass polyvinyl alcohol solution; the ratio of the ceramic powder to the 3% by mass polyvinyl alcohol solution is (25-100) g and: 1 mL; Preferably, the granulation is followed by screening, wherein the screening is through a 40-60 mesh sieve.

9. The preparation method according to any one of claims 3 to 8, It is characterized in that In step (3), the sintering temperature is 1200-1600° C. and the sintering holding time is 4-6 hours; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 1 / 2 A1 1 / 2 Ta 2 O 6 When the sintering temperature is 1300-1500°C; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 1 / 3 A1 1 / 3 A2 1 / 3 Ta 2 O 6 When the sintering temperature is 1300-1500°C; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 0.25 A1 0.25 A2 0.25 A3 0.25 Ta 2 O 6 When the sintering temperature is 1200-1600°C; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 0.2 A1 0.2 A2 0.2 A3 0.2 A4 0.2 Ta 2 O 6 When the sintering temperature is 1300-1600°C; Preferably, when the chemical composition of the magnesium tantalate-based microwave dielectric material is Mg 1 / 6 A1 1 / 6 A2 1 / 6 A3 1 / 6 A4 1 / 6 A5 1 / 6 Ta 2 O 6 When the sintering temperature is 1300-1500°C; Preferably, the sintering temperature rise system includes: firstly heating the temperature at a heating rate of 5°C / min to a temperature 100°C lower than the sintering temperature, and then heating the temperature at a heating rate of 1°C / min to the sintering temperature.

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