A tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic and its preparation method

Abstract

This invention discloses a tungsten bronze-structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic and its preparation method, belonging to the field of microwave dielectric ceramics. The chemical formula of the microwave dielectric ceramic is Ba4(La). 1 / 5Pr 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 ) 28 / 3 Ti 18 O 54 Its preparation method includes: mixing raw materials BaCO3, La2O3, and Pr6O 11 Nd₂O₃, Sm₂O₃, Eu₂O₃, and TiO₂ were formulated according to their chemical formulas, ball-milled, dried, and pre-fired at 1100–1200℃. After a second ball milling, drying, granulation, and sieving, the mixture was pressed into a green body and sintered at 1350–1500℃ to obtain a tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic. This invention introduces the concept of high entropy into tungsten bronze structure barium lanthanum titanium-based microwave dielectric ceramics for the first time. By controlling process parameters such as pre-firing temperature, sintering temperature, and sintering time, a high-entropy microwave dielectric ceramic with a single-phase tungsten bronze structure was successfully prepared. The high-entropy ceramic prepared by this invention exhibits excellent microwave dielectric properties, including a high dielectric constant, a high quality factor, and a low temperature coefficient of resonant frequency, and is expected to be widely used in the field of mobile communications.

Description

Technical Field

[0001] This invention belongs to the field of microwave dielectric ceramics, specifically relating to a tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic and its preparation method. Background Technology

[0002] Microwave dielectric ceramics are key materials for fabricating microwave components (including dielectric resonant antennas, dielectric filters, dielectric substrates, microwave transmission lines, etc.), and have wide applications in 5G / 6G communication systems, satellite communication, global positioning systems, wireless local area networks, automotive radar, and radio frequency identification. High-performance microwave dielectric ceramics require suitable dielectric constants (high dielectric constant materials are used for device miniaturization, dielectric constant materials are used for base stations and satellite communication, and low dielectric constant materials are used for substrates and millimeter-wave antennas), quality factors, and small temperature coefficients of resonant frequencies.

[0003] High-entropy oxides are a novel class of ceramic materials that have emerged in recent years. They consist of five or more oxides in equimolar or near-equimolar ratios and can form a single-phase solid solution structure under certain temperature conditions. Compared with traditional oxides, high-entropy oxides exhibit superior physicochemical properties, including dielectric, mechanical, thermal, and catalytic properties, due to their unique composition and lattice distortion effects. The synthesis of pure phases is currently a challenge in the preparation of high-entropy ceramics, as the presence of impurity phases severely affects their properties and hinders their applications. Furthermore, although tungsten bronze high-entropy ceramics have wide applications in thermoelectric and ferroelectric fields, there are currently no reports on the preparation of tungsten bronze-structured barium-lanthanum-titanium high-entropy microwave dielectric ceramics. Summary of the Invention

[0004] To address the shortcomings of existing technologies and to expand the application fields of tungsten bronze high-entropy ceramics, the present invention aims to provide a tungsten bronze barium lanthanum titanium-based high-entropy microwave dielectric ceramic and its preparation method. This tungsten bronze barium lanthanum titanium-based high-entropy microwave dielectric ceramic possesses advantages such as high dielectric constant, high quality factor, and low resonant frequency temperature coefficient, and can be widely used in the field of mobile communications.

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

[0006] A tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic, wherein the chemical formula of the high-entropy microwave dielectric ceramic is Ba4(La) 1 / 5 Pr 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 ) 28 / 3 Ti 18 O 54 .

[0007] Preferably, the raw materials for the high-entropy microwave dielectric ceramic include: BaCO3, La2O3, and Pr6O. 11 , Nd2O3, Sm2O3, Eu2O3, TiO2.

[0008] Preferably, the purity of the raw material for the high-entropy microwave dielectric ceramic is greater than 99%.

[0009] Based on the factor of crystal structure stability, this invention uses raw materials containing five lanthanide elements (La, Pr, Nd, Sm, and Eu) in equal proportions to prepare barium-lanthanum-titanium microwave dielectric ceramics. These ceramics exhibit a configuration entropy greater than 1.60R and a stable single-phase tungsten bronze structure. The ceramic surface is dense, with uniformly distributed rod-shaped grains, and its overall dielectric properties are superior to Ba4X. 28 / 3 Ti 18 O 54 Ceramic materials (where X is one of La, Pr, Nd, or Sm) are superior and are expected to be widely used in the field of mobile communications.

[0010] The preparation method of the high-entropy microwave dielectric ceramic specifically includes the following steps:

[0011] (1) The raw materials BaCO3, La2O3, and Pr6O 11 Nd₂O₃, Sm₂O₃, Eu₂O₃, TiO₂ according to the chemical formula Ba₄(La) 1 / 5 Pr 1 / 5 Nd 1 / 5Sm 1 / 5 Eu 1 / 5 ) 28 / 3 Ti 18 O 54 Mix evenly in a dry environment;

[0012] (2) Put the mixed raw materials into a ball mill and add deionized water for ball milling. The ball milling time is 1 to 4 hours. Then dry at 120°C for 8 to 12 hours and sieve to obtain powder.

[0013] (3) Put the powder into an alumina crucible and place it together in a high-temperature muffle furnace for pre-firing. Keep it at 1100~1200℃ for 2~4 hours.

[0014] (4) Put the pre-calcined powder into a ball mill and add deionized water for secondary ball milling. The ball milling time is 1 to 4 hours. Then dry it at 120°C for 8 to 12 hours.

[0015] (5) Use an 8% polyvinyl alcohol solution as a binder, granulate, and sieve;

[0016] (6) A powder tablet press is used to press the material to obtain the preform;

[0017] (7) The blank is sintered at 1350-1500℃ and held for 2-6 h to obtain a tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic material.

[0018] (8) Test the microwave dielectric properties of the high-entropy microwave dielectric ceramic.

[0019] Preferably, the ball mill mentioned in steps (2) and (4) is a planetary ball mill.

[0020] Preferably, the sieving in steps (2) and (5) is done through a 60-mesh sieve.

[0021] Preferably, the amount of binder added in step (5) is 6% to 10% of the mass of the mixture to be granulated.

[0022] Preferably, the forming pressure of the powder tablet press in step (6) is 100 MPa.

[0023] Preferably, the diameter of the blank in step (6) is 8 mm and the thickness of the blank is 2 to 6 mm.

[0024] Preferably, the pre-firing in step (3) is carried out in an air atmosphere.

[0025] Preferably, the sintering in step (7) is carried out in an air atmosphere.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] 1. This invention introduces the concept of high entropy into tungsten bronze structure barium lanthanum titanium-based microwave dielectric ceramics. By controlling process parameters such as pre-sintering temperature, ball milling time, sintering temperature, and sintering time, microwave dielectric ceramics with a single-phase tungsten bronze structure were successfully prepared.

[0028] 2. The tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic provided by this invention has excellent comprehensive microwave dielectric properties, with a relative permittivity of up to 85.34, a quality factor of up to 10456 GHz, and a resonant frequency temperature coefficient of 26.8 ppm / ℃.

[0029] 3. The tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic provided by this invention enriches the high-entropy ceramic material system and has excellent comprehensive microwave dielectric properties, which can be widely used in 5G / 6G mobile communication and other fields. Attached Figure Description

[0030] Figure 1 This is a crystal structure diagram of the tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic of the present invention;

[0031] Figure 2X-ray diffraction patterns of the tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramics prepared in Examples 1-4 of this invention;

[0032] Figure 3 Scanning electron microscope images of the tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramics prepared in Examples 1-4 of this invention.

[0033] Figure 4 The X-ray energy spectrum of the tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramics prepared in Examples 1-4 of this invention is shown. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0035] The tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic provided by this invention uses BaCO3, La2O3, and Pr6O with a purity greater than 99%. 11 Nd₂O₃, Sm₂O₃, Eu₂O₃, and TiO₂ were used as initial raw materials to prepare the product via a traditional solid-state method. Specific embodiments are as follows:

[0036] Example 1

[0037] The tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic of this embodiment is prepared by the following steps:

[0038] (1) BaCO3, La2O3, and Pr6O with a purity greater than 99% 11 Nd₂O₃, Sm₂O₃, Eu₂O₃, TiO₂ according to the chemical formula Ba₄(La) 1 / 5 Pr 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 ) 28 / 3 Ti 18 O 54 Mix evenly;

[0039] (2) After mixing the raw materials, deionized water is added and the mixture is put into a planetary ball mill for ball milling for 2 hours. Then the ball-milled slurry is put into an oven and dried at 120°C. The dried powder is then passed through a 60-mesh sieve to obtain powder with uniform particles.

[0040] (3) The powder is loaded into an alumina crucible and placed into a high-temperature muffle furnace for pre-firing, and kept at 1150°C for 3 hours.

[0041] (4) The pre-calcined powder is placed in a planetary ball mill and deionized water is added for secondary ball milling for 2 hours; then the ball-milled slurry is placed in an oven and dried at 120°C.

[0042] (5) Use a polyvinyl alcohol solution with a mass fraction of 8% as a binder. The amount of binder added is 6% of the mass of the mixture to be granulated. Granulate and pass through a 60-mesh sieve to obtain powder with uniform particles.

[0043] (6) A powder tablet press is used to press the blank to obtain a blank. The forming pressure of the powder tablet press is 100MPa; the diameter of the blank is 8mm and the thickness of the blank is 2~6mm.

[0044] (7) The blank was placed in a high-temperature muffle furnace and sintered at 1350℃ for 4 hours to obtain a tungsten bronze structure barium lanthanum titanium system high-entropy microwave dielectric ceramic material.

[0045] (8) Test the microwave dielectric properties, X-ray diffraction pattern, scanning electron microscope image and X-ray energy spectrum of the high-entropy microwave dielectric ceramic.

[0046] Example 2

[0047] The preparation method of the tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic in this embodiment is basically the same as that in Example 1, except that the sintering temperature in step (7) is 1400℃.

[0048] Example 3

[0049] The preparation method of the tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic in this embodiment is basically the same as that in Example 1, except that the sintering temperature in step (7) is 1450℃.

[0050] Example 4

[0051] The preparation method of the tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic in this embodiment is basically the same as that in Example 1, except that the sintering temperature in step (7) is 1500℃.

[0052] The microwave dielectric properties of the tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramics prepared in Examples 1-4 were tested using a Keysight P9373A network analyzer. The test results are detailed in Table 1. As shown in Table 1, the tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramics provided by this invention possess excellent comprehensive microwave dielectric properties. The high-entropy microwave dielectric ceramics prepared at the optimal sintering temperature (Example 2, 1400 ℃) have a dielectric constant of 85.34, a quality factor of 10456 GHz, and a resonant frequency temperature coefficient of 26.8 ppm / ℃.

[0053] Table 1: Microwave dielectric properties of tungsten bronze-structured barium lanthanum titanium-based high-entropy microwave dielectric ceramics prepared in Examples 1-4

[0054]

[0055] This invention provides a tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic, using raw materials BaCO3, La2O3, and Pr6O. 11 Ba4(La) was prepared from Nd2O3, Sm2O3, Eu2O3, and TiO2. 1 / 5 Pr 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 ) 28 / 3Ti 18 O 54 High-entropy microwave dielectric ceramics possess excellent overall microwave dielectric properties. The inventors have also targeted other lanthanide element combinations (such as Ba₄(Gd₂)₃) 1 / 5 Ho 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 ) 28 / 3 Ti 18 O 54 Ba4(Gd 1 / 5 Er 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 ) 28 / 3 Ti 18 O 54 and Ba4(Er 1 / 5 Ho 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 ) 28 / 3 Ti 18 O 54 (Etc.) prepared barium lanthanum titanium-based high-entropy microwave dielectric ceramics and found that the prepared dielectric ceramics did not exhibit microwave dielectric properties, and their X-ray diffraction patterns showed the presence of a second phase.

[0056] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic, characterized in that, The high-entropy microwave dielectric ceramic has a chemical formula of Ba4(La 1 / 5 Pr 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 ) 28 / 3 Ti 18 O 54 ; The preparation method of the high-entropy microwave dielectric ceramic includes the following steps: mixing the raw materials according to the chemical formula ratio, ball milling, drying, and sieving; pre-firing the powder at 1100~1200℃ for 2~4 hours; ball milling again, drying, granulation, sieving, pressing, and sintering the green body at 1350~1450℃ for 2~6 hours to obtain a tungsten bronze structure barium lanthanum titanium-based high-entropy microwave dielectric ceramic.

2. The tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic according to claim 1, characterized in that, The raw materials for the high-entropy microwave dielectric ceramic include: BaCO3, La2O3, and Pr6O. 11 , Nd2O3, Sm2O3, Eu2O3, TiO2.

3. The tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic according to claim 2, characterized in that, The purity of the raw material is greater than 99%.

4. The tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic according to claim 1, characterized in that, The ball milling process was carried out using a planetary ball mill.

5. The tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic according to claim 1, characterized in that, The granulation process uses an 8% polyvinyl alcohol solution as a binder; the amount of binder added is 6% to 10% of the mass of the mixture to be granulated.

6. The tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic according to claim 1, characterized in that, All sieving processes involved passing through a 60-mesh sieve.

7. The tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic according to claim 1, characterized in that, The diameter of the blank is 8 mm and the thickness of the blank is 2~6 mm.

8. The tungsten bronze structured barium lanthanum titanium-based high-entropy microwave dielectric ceramic according to claim 1, characterized in that, Both the pre-firing and sintering are carried out in an air atmosphere.

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