Low-dielectric high-entropy high-Q microwave dielectric ceramic material and preparation method thereof

Abstract

The application relates to the technical field of electronic information functional materials, and particularly relates to a low-dielectric high-entropy high-Q microwave dielectric ceramic material and a preparation method thereof. 0.2 B 0.2 C 0.2 D 0.2 E 0.2 )2BaZn 1‑x Mg x O5, wherein B, C, D and E are selected from one of La-based rare elements, 0 < x < 0.1, and the application further provides a preparation method of the low-dielectric high-entropy high-Q microwave dielectric ceramic material, which comprises the steps of batching, ball milling, drying and sieving, pre-sintering, granulating, mold pressing, long-time calcining and annealing. The material prepared by the application has a high-entropy pure-phase orthorhombic crystal structure, a highly dense micro-morphology without pores and micro-cracks, a high quality factor and a small resonance frequency temperature coefficient, a dielectric constant of 14-18, a high Qxf value of 30,000-70,000 GHz, and a tunable t f value of-30-8 ppm / DEG C. The formula does not contain volatile toxic metals such as Pb and Cd, the performance is stable, and the material is suitable for a high-frequency microwave communication system.

Description

Technical Field

[0001] This invention relates to the field of electronic information functional materials technology, and in particular to a low-dielectric-high-entropy-high-Q microwave dielectric ceramic material and its preparation method. Background Technology

[0002] Microwave dielectric ceramics are key materials for microwave components such as resonators, filters, and dielectric substrates used in modern mobile communications, satellite communications, and military radar. Higher frequencies are an inevitable trend in the development of digital products. As electronic information technology continues to evolve towards higher frequencies and digitalization, the demand for miniaturization, integration, and modularization of components is becoming increasingly urgent. In high-frequency microwave circuits, many microwave devices require dielectric ceramic materials as substrates, making microwave ceramic dielectric substrate materials increasingly crucial basic materials used in microwave devices, components, and complete systems.

[0003] Dielectric constant is a key performance characteristic of dielectric ceramic substrates, and its range often determines the applicable direction of the substrate material. For example, substrates with a relative dielectric constant below 15 are suitable for high-speed digital circuit design; substrates with a relative dielectric constant of 15-80 can well complete the design of high-frequency circuits; and substrates with a relative dielectric constant as high as 20,000 can integrate high-capacitive devices into multilayer structures. Developing microwave dielectric ceramic materials with low dielectric constants (below 20) to meet the requirements of high frequency and high speed is a key research and development direction for microwave dielectric ceramics. Since a higher quality factor Q×f value for microwave dielectric ceramic materials results in lower insertion loss for filters, a higher quality factor is beneficial for achieving good frequency selectivity in microwave devices, while a near-zero frequency temperature coefficient τ... f This means that the center frequency of the device changes little with ambient temperature, resulting in high operational stability. Therefore, developing microwave dielectric ceramic materials that simultaneously possess tunable dielectric constants within a certain range, ultra-low losses, and near-zero frequency temperature coefficients at microwave frequencies has significant application value.

[0004] The performance of microwave dielectric ceramics depends primarily on the properties of the selected materials. In recent years, significant research and development efforts have focused on advancing novel microwave dielectric ceramics to improve their dielectric properties. These properties include lower dielectric constants, higher quality factors, and desired temperature coefficients for resonant frequencies. Among these, high-entropy design has received considerable attention in recent years. It induces local structural disorder by combining multiple ions, thereby reducing the tilt of oxygen octahedra and improving the temperature coefficient. Furthermore, the high-entropy design strategy can also induce a phase transition from order to disorder, thus improving the material's quality factor. The unique aspect of this strategy lies in the "cocktail effect" produced by the combination of multiple ions, which comprehensively optimizes multiple performance indicators of the ceramic.

[0005] Recent research has shown that ceramics synthesized using high-entropy design exhibit great potential in enhancing microwave dielectric properties. These high-performance ceramics are expected to surpass traditional ceramic materials and meet the stringent requirements of high-frequency microwave system applications. For example, Fang Liang's team at Guilin University of Technology successfully synthesized and utilized high-entropy optimization of Li(Gd) 0.2 Ho 0.2 Er 0.2 Yb 0.2 Lu 0.2 The dielectric properties of GeO4 ceramics demonstrate the great potential of high-entropy strategies in the development of microwave dielectric materials. The dielectric property of this material is ε0. r = 7.2, Q×f = 29,000 GHz, τ f = −2.9~5.3 ppm / ℃. Compared with A2BO4 (A = Ca, Mg; B = Si, Ge) and LiREGeO4 olivine, high-entropy LiREGeO4 simultaneously obtained improved Q×f and τ. f The dielectric properties of unmodified LiYGeO4 are ε. r = 9.41, Q×f = 18,860 GHz, τ f = −27.7 ppm / °C. τ f Improvements can be made through high-entropy strategies in Li(Gd 0.2 Ho 0.2 Er 0.2 Yb 0.2 Lu 0.2 This can be explained by reducing the tilt of the [ReO6] oxygen octahedrons in GeO4. Under the dominance of high-entropy and lattice distortion effects, the tilt or distortion of the oxygen polyhedra is effectively modulated. This is likely the most important reason for the improved microwave dielectric properties.

[0006] In addition, Song Kaixin's team at Hangzhou Dianzi University successfully prepared Sr(La) using a high-entropy strategy. 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 Compared to unmodified SrLaAlO4 ceramics, high entropy successfully increased the material's τ. fThe value was adjusted from a relatively large −32 ppm / °C to a near-zero −6 ppm / °C, and the compressive strength of the material was significantly increased from 583 MPa to 1040 MPa. This result shows that high entropy facilitates the formation of fine grains in ceramics, thereby significantly altering their mechanical properties. The use of a high-entropy strategy in microwave dielectric ceramics shows promise for achieving materials with excellent performance and expanded applications. Order-disorder phase transitions and lattice distortions also provide an important method for adjusting the temperature coefficient of quality factor and resonant frequency. Y₂BaZnO₅ ceramics themselves have extremely high Q×f values, reaching 10,000 GHz after sintering for 6 to 8 hours, but their τ... f The value is relatively high, at -41 ppm / °C.

[0007] In summary, high entropy is a novel approach to comprehensively adjust the temperature coefficient and Q-value performance of microwave dielectric ceramics. Based on this idea, this invention provides a new type of microwave dielectric ceramic with low dielectric constant, high quality factor (Q-value), and small temperature coefficient, which can meet the needs of the microwave communication industry. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a low-dielectric, high-entropy, high-Q microwave dielectric ceramic material and its preparation method.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] This invention provides a low-dielectric-high-entropy, high-Q microwave dielectric ceramic material with the chemical formula (Y). 0.2 B 0.2 C 0.2 D 0.2 E 0.2 )2BaZn 1-x Mg x O5, where A, B, C, and D are selected from one of the rare elements in the La series, and 0 < x < 0.1.

[0011] In some embodiments, the La-series rare elements include Nd, Sm, Eu, Gd, Er, Tm, and Yb.

[0012] In some embodiments, the dielectric constant of the low-dielectric, high-entropy, high-Q microwave dielectric ceramic material is 14~18, the Q×f value is between 30,000 and 70,000 GHz, and the τf value is -30~-8 ppm / ℃.

[0013] This invention also provides a method for preparing a low-dielectric, high-entropy, high-Q microwave dielectric ceramic material, comprising the following steps:

[0014] A. Mix raw materials Mg(OH)₂·4MgCO₃·5H₂O, yttrium oxide, barium carbonate, zinc oxide, and lanthanide oxides according to the molar ratios specified in the chemical formulas to obtain a mixture for later use; according to the general chemical formula (Y 0.2 B 0.2 C 0.2 D 0.2 E 0.2 )2BaZn 1- x Mg x Calculate the molar ratios of Mg(OH)2·4MgCO3·5H2O, yttrium oxide, barium carbonate, zinc oxide, and lanthanide oxides.

[0015] B. One-time ball milling: Using zirconia balls as the ball milling medium, the mixture from step A is mixed with zirconia balls and anhydrous ethanol and milled for 5-7 hours to obtain a uniformly mixed ball milling material.

[0016] C. Drying and sieving: Dry the ball milling material obtained in step B and sieve it through a 100-mesh sieve to obtain dry powder;

[0017] D. Pre-calcination: The dried powder obtained in step C is placed in an alumina crucible and pre-calcined to obtain pre-calcined powder;

[0018] E. Secondary ball milling: The pre-calcined powder obtained in step D is subjected to a second ball milling. Zirconia balls are used as the ball milling medium. The pre-calcined powder, zirconia balls, and anhydrous ethanol are mixed and ground for 2-4 hours to obtain secondary ball milling material.

[0019] F. Drying and sieving: The secondary ball milling material obtained in step E is dried and sieved through a 100-mesh sieve to obtain dried powder;

[0020] G. Granulation and molding: The dried powder obtained in step F is mixed with polyvinyl alcohol aqueous solution and then granulated. The granulation size is controlled at 80~100 mesh. The granules are placed in a molding die and dry-pressed to obtain a green body.

[0021] H. Sintering: The green blank obtained in step G is placed in a sintering furnace and sintered and annealed to obtain a low dielectric high entropy high Q value microwave dielectric ceramic material.

[0022] In some embodiments, in step A, the lanthanide oxide is selected from any four of neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, erbium oxide, thulium oxide, and ytterbium oxide, and the proportions follow the general chemical formula (Y). 0.2 B 0.2 C 0.2 D 0.2 E 0.2 )2BaZn 1-x Mg x O5 molar ratio.

[0023] In some embodiments, in step B, the mass ratio of the mixture, zirconia balls and absolute ethanol is 1:(5 - 7):(2 - 4).

[0024] In some embodiments, in step D, the pre-sintering temperature is 900 - 1000 °C and the pre-sintering time is 3 - 5 hours.

[0025] In some embodiments, in step E, the mass ratio of the pre-sintered powder, zirconia balls and absolute ethanol is 1:(3 - 5):(1 - 2).

[0026] In some embodiments, in step H, the sintering furnace is heated at a heating rate of 3 - 5 °C / min, sintered at 1250 - 1350 °C for 6 - 10 hours, then cooled to 850 °C at a rate of 3 °C / min, and annealed for 4 hours to obtain a low dielectric high entropy high Q-value microwave dielectric ceramic material.

[0027] The present invention can use any suitable raw materials to form a chemical formula of (Y 0.2 B 0.2 C 0.2 D 0.2 E 0.2 )2BaZn 1-x Mg x O5, where B, C, D, and E represent rare earth elements of the La series, including La, Nd, Sm, Eu, Gd, Er, Tm, and Yb elements, and 0 < x < 0.1. By prolonging the sintering time and adding an annealing process, the present invention provides a good growth environment for grains to reduce internal stress, thereby ensuring that the microstructure of the prepared microwave dielectric ceramic material is highly dense, pore-free and micro-crack-free. And by comprehensively regulating the combination of high entropy elements at the Y-site (i.e., the elements corresponding to the B, C, D, and E positions) and the substitution content of Mg elements at the Zn-site, the structural distortion degree is comprehensively adjusted and excellent comprehensive performance is obtained. The ceramic has a typical orthorhombic structure and no secondary phase, indicating the formation of a single-phase solid solution. The dielectric constant is between 14 and 18, the high Q×f value is between 30,000 and 70,000 GHz, the τ f value is adjustable between - 30 and - 8 ppm / °C, and the resonance frequency is 8.8 - 9.6 GHz. The comprehensive performance meets the application requirements of high frequency.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] 1. In the formulation of this invention, the structural distortion and sintering characteristics are comprehensively adjusted by regulating the combination of high-entropy elements at the Y-site and the Mg element substitution content at the Zn-site, thereby achieving the purpose of comprehensively regulating microwave dielectric properties. This invention provides a good growth environment for grains and reduces internal stress by extending the sintering time and adding an annealing process, thus ensuring that the prepared microwave dielectric ceramic material has a highly dense microstructure, is free of pores and microcracks, and achieves a significant improvement in performance. Existing technologies for preparing related microwave dielectric ceramic materials mostly employ individual element substitution methods. For example, the Ogawa team at Meiji University in Japan used Tm, Eu, Gd, Dy, Ho, and Er to individually substitute elements at the Y-site, resulting in improved material properties ε. r Between 16 and 19, the Q×f value is between 2,000 and 29,000 GHz, and its resonant frequency temperature coefficient is between -28 and -4 ppm / ℃, resulting in excessive losses that are unsuitable for practical production applications. For example, the Ohsato team in Japan used Sm to replace the Y-site element, and its ε... r Between 16 and 17 GHz, the Q×f value ranges from 25,000 to 90,000 GHz, and its resonant frequency temperature coefficient is -41 ppm / ℃, which is excessively large. In contrast, the microwave dielectric ceramic material provided by this invention exhibits a typical rock-salt type relative permittivity ε. r Adjustable between 14 and 18, Q×f value is 30,000 GHz to 70,000 GHz, and the temperature coefficient of resonant frequency τ f It is adjustable between -30 and -8 ppm / °C and has stable performance, meeting the application requirements of modern microwave devices.

[0030] 2. The microwave dielectric ceramic material of this invention does not contain volatile toxic metals such as Pb and Cd, and can be widely used in microwave devices such as dielectric resonators, filters, and oscillators in high-frequency satellite communications. It is green, environmentally friendly, and pollution-free, and meets the strict standards of the latest European Community RHOS (Restriction of Hazardous Substances Directive in Electrical and Electronic Equipment) and the WEEE (Weather Engineering and Equipment) regulations.

[0031] 3. The sintering temperature of the microwave dielectric ceramic material of the present invention is 1250~1350℃, which has a wide sintering temperature range and good process adaptability.

[0032] 4. The raw materials used in the formulation of this invention are all simple carbonates and oxides, which can be synthesized in one step without additional synthesis processes, and are far superior to raw materials that require separate synthesis. This invention uses an annealing process to release the crystal surface stress of the material and improve its loss performance. Attached Figure Description

[0033] Figure 1These are XRD patterns of Embodiments 1, 2, 4, 6, and 8 of the present invention;

[0034] Figure 2 The Raman diffraction patterns of Examples 2, 3, 5, 7, and 8 of this invention are shown below.

[0035] Figure 3 This is a SEM image of Embodiment 3 of the present invention. Detailed Implementation

[0036] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0037] The technical solutions in some embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure.

[0038] Unless the context otherwise requires, throughout the specification and claims, the term "comprise" and its other forms, such as the third-person singular "comprises" and the present participle "comprising," are interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemply embodiments," "example," "specific example," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0039] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. The singular forms "a" and "the" as used in this specification and the appended claims also include a plurality of indicators, unless explicitly stated otherwise. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality" means two or more.

[0040] "At least one of A, B and C" has the same meaning as "at least one of A, B or C", both including the following combinations of A, B and C: only A, only B, only C, combinations of A and B, combinations of A and C, combinations of B and C, and combinations of A, B and C.

[0041] Example

[0042] This invention provides a low-dielectric-high-entropy, high-Q microwave dielectric ceramic material with the chemical formula (Y). 0.2 B 0.2 C 0.2 D 0.2 E 0.2 )2BaZn 1-x Mg x O5, wherein B, C, D, and E are selected from the rare elements of the La series, 0 < x < 0.1, and by way of example, x can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or 0.09. The embodiments of this application do not impose specific limitations.

[0043] In some embodiments, the La-series rare elements include Nd, Sm, Eu, Gd, Er, Tm, and Yb. Exemplarily, B, C, D, and E can be selected from Nd, Sm, Eu, Gd or Nd, Sm, Er, Tm or Sm, Nd, Yb, Tm or Sm, Eu, Gd, Er or Eu, Gd, Er, Tm or Gd, Er, Tm, Yb or Nd, Sm, Gd, Er or Sm, Eu, Tm, Yb. The embodiments of this application do not impose specific limitations.

[0044] In some embodiments, the dielectric constant of the low-dielectric, high-entropy, high-Q microwave dielectric ceramic material is 14~18, the Q×f value is between 30,000 and 70,000 GHz, and the τf value is -30~-8 ppm / ℃.

[0045] This invention also provides a method for preparing a low-dielectric, high-entropy, high-Q microwave dielectric ceramic material, comprising the following steps:

[0046] A. Mix the raw materials Mg(OH)2·4MgCO3·5H2O, yttrium oxide, barium carbonate, zinc oxide and lanthanide oxides to obtain a mixture for later use;

[0047] B. One-time ball milling: Using zirconia balls as the ball milling medium, the mixture from step A is mixed with zirconia balls and anhydrous ethanol and milled for 5-7 hours to obtain a uniformly mixed ball milling material.

[0048] C. Drying and sieving: Dry the ball milling material obtained in step B and sieve it through a 100-mesh sieve to obtain dry powder;

[0049] D. Pre-calcination: The dried powder obtained in step C is placed in an alumina crucible and pre-calcined to obtain pre-calcined powder;

[0050] E. Secondary ball milling: The pre-calcined powder obtained in step D is subjected to a second ball milling. Zirconia balls are used as the ball milling medium. The pre-calcined powder, zirconia balls, and anhydrous ethanol are mixed and ground for 2-4 hours to obtain secondary ball milling material.

[0051] F. Drying and sieving: The secondary ball milling material obtained in step E is dried and sieved through a 100-mesh sieve to obtain dried powder;

[0052] G. Granulation and molding: The dried powder obtained in step F is mixed with polyvinyl alcohol aqueous solution and then granulated. The granulation size is controlled at 80~100 mesh. The granules are placed in a molding die and dry-pressed to obtain a green body.

[0053] H. Sintering: The green blank obtained in step G is placed in a sintering furnace and sintered and annealed to obtain a low dielectric high entropy high Q value microwave dielectric ceramic material.

[0054] In some embodiments, in step A, the lanthanide oxide is selected from any four of neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, erbium oxide, thulium oxide, and ytterbium oxide. For example, it is selected from neodymium oxide, samarium oxide, europium oxide, ytterbium oxide, or neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, or samarium oxide, europium oxide, gadolinium oxide, erbium oxide, or europium oxide, gadolinium oxide, erbium oxide, thulium oxide, or gadolinium oxide, erbium oxide, thulium oxide, ytterbium oxide. The embodiments of this application do not make specific limitations.

[0055] In some embodiments, in step B, the mass ratio of the mixture, zirconium dioxide balls, and anhydrous ethanol is 1:(5~7):(2~4). Exemplarily, this mass ratio can be 1:5:2, 1:6:3, 1:5:3, 1:6:2, 1:7:4, 1:6:4, 1:7:2, or 1:7:3. This application does not impose specific limitations on these embodiments.

[0056] In some embodiments, in step D, the pre-firing temperature is 900~1000℃ and the pre-firing time is 3~5 hours. Exemplary pre-firing temperatures are 900℃, 950℃, 980℃, 990℃, and 1000℃, and pre-firing times are 3 hours, 4 hours, and 5 hours. This application embodiment does not make specific limitations.

[0057] In some embodiments, in step E, the mass ratio of the pre-calcined powder, zirconium dioxide balls, and anhydrous ethanol is 1:(3~5):(1~2). Exemplarily, this mass ratio can be 1:3:1, 1:4:1, 1:5:1, 1:4:2, 1:5:2, or 1:3:2. This application does not impose specific limitations on these embodiments.

[0058] In some embodiments, in step H, the sintering furnace is heated at a rate of 3-5 °C / min and sintered at 1250-1350 °C for 6-10 hours, then cooled to 850 °C at a rate of 3 °C / min and annealed for 4 hours to obtain a low-dielectric, high-entropy, high-Q microwave dielectric ceramic material. Exemplarily, the sintering temperature can be 1250 °C, 1260 °C, 1270 °C, 1280 °C, 1290 °C, 1300 °C, 1310 °C, 1320 °C, 1330 °C, 1340 °C, or 1350 °C. This application does not impose specific limitations on these embodiments.

[0059] Table 1 shows the mass percentage of each raw material in the total raw material in each embodiment. The raw materials were weighed according to the percentage content in Table 1.

[0060] Table 1. Percentage of each raw material in each embodiment

[0061]

[0062] Example 1

[0063] Step 1: Prepare raw materials Y2O3, BaCO3, ZnO, basic magnesium carbonate, Nd2O3, Sm2O3, Eu2O3, and Gd2O3 in the following mass ratios: 5.11%, 44.69%, 18.06%, 0.44%, 7.62%, 7.90%, 7.97%, and 8.21%, respectively. Grind the resulting mixture for 6 hours using zirconia balls as the milling medium and anhydrous ethanol as the solvent, with a weight ratio of mixture:zirconia balls:anhydrous ethanol of 1:5:2, to obtain a homogeneous mixture.

[0064] Step 2: The ball-milled mixture is dried at 80°C and passed through a 100-mesh sieve to obtain a dry powder. Then, it is pre-calcined at 1000°C for 4 hours to obtain a sample calcined block.

[0065] Step 3: Crush the sample block into powder, use zirconium dioxide balls as the ball milling medium and anhydrous ethanol as the solvent, grind for 3 hours according to the weight ratio of sample block: zirconium dioxide balls: anhydrous ethanol of 1:5:2, dry and granulate, control the particle size to 100 mesh, put the granules into the molding mold and dry press to obtain the green body.

[0066] Step 4: The green body obtained in Step 4 is sintered at 1250℃ for 6 hours and then annealed at 850℃ for 4 hours to obtain the final microwave dielectric ceramic material, denoted as (R1)2BaZnO5.

[0067] Example 2

[0068] Step 1: Prepare raw materials Y2O3, BaCO3, ZnO, basic magnesium carbonate, Nd2O3, Sm2O3, Er2O3, and Tm2O3 in the following mass ratios: 5.05%, 44.12%, 17.47%, 0.87%, 7.52%, 7.80%, 8.55%, and 8.63%, respectively. Grind the resulting mixture for 7 hours using zirconia balls as the ball milling medium and anhydrous ethanol as the solvent, with a weight ratio of mixture:zirconia balls:ethanol of 1:5:2, to obtain a homogeneous mixture.

[0069] Step 2: The ball-milled mixture is dried at 80°C and passed through a 100-mesh sieve to obtain a dry powder. Then, it is pre-calcined at 980°C for 4 hours to obtain a sample calcined block.

[0070] Step 3: Crush the sample calcined block, use zirconium dioxide balls as the ball milling medium and anhydrous ethanol as the solvent, grind for 3 hours according to the weight ratio of sample calcined block: zirconium dioxide balls: ethanol of 1:5:2, dry and granulate, control the particle size to 100 mesh, put the granules into the molding mold and dry press to obtain the green body.

[0071] Step 4: The green body obtained in Step 4 is sintered at 1290℃ for 8 hours and then annealed at 850℃ for 4 hours to obtain the final microwave dielectric ceramic material, denoted as (R2)2BaZnO5.

[0072] Example 3

[0073] Step 1: Prepare raw materials Y2O3, BaCO3, ZnO, basic magnesium carbonate, Sm2O3, Eu2O3, Gd2O3, and Er2O3 in the following mass ratios: 5.03%, 43.98%, 17.05%, 1.30%, 7.50%, 7.77%, 8.60%, and 8.78%, respectively. Grind the resulting mixture for 7 hours using zirconia balls as the milling medium and anhydrous ethanol as the solvent, with a weight ratio of mixture:zirconia balls:anhydrous ethanol of 1:5:2, to obtain a homogeneous mixture.

[0074] Step 2: The ball-milled mixture is dried at 80°C and passed through a 100-mesh sieve to obtain a dry powder. Then, it is pre-calcined at 950°C for 4 hours to obtain a sample calcined block.

[0075] Step 3: Crush the sample block into powder, use zirconium dioxide balls as the ball milling medium and anhydrous ethanol as the solvent, grind for 4 hours according to the weight ratio of sample block: zirconium dioxide balls: anhydrous ethanol of 1:5:2, dry and granulate, control the particle size to 100 mesh, put the granules into the molding mold and dry press to obtain the green body.

[0076] Step 4: The green body obtained in Step 4 is sintered at 1310℃ for 10 hours and then annealed at 850℃ for 4 hours to obtain the final microwave dielectric ceramic material, denoted as (R3)2BaZnO5.

[0077] Example 4

[0078] Step 1: Prepare raw materials Y2O3, BaCO3, ZnO, basic magnesium carbonate, Nd2O3, Sm2O3, Tm2O3, and Yb2O3 in the following mass ratios: 5.05%, 44.14%, 16.74%, 1.74%, 7.80%, 7.87%, 8.11%, and 8.55%, respectively. Grind the resulting mixture for 8 hours using zirconia balls as the milling medium and anhydrous ethanol as the solvent, with a weight ratio of mixture:milling balls:ethanol of 1:5:2, to obtain a homogeneous mixture.

[0079] Step 2: The ball-milled mixture is dried at 80°C and passed through a 100-mesh sieve to obtain a dry powder. Then, it is pre-calcined at 990°C for 4 hours to obtain a sample calcined block.

[0080] Step 3: Crush the sample block into powder, use zirconium dioxide balls as the ball milling medium and anhydrous ethanol as the solvent, grind for 3 hours according to the weight ratio of sample block: zirconium dioxide balls: anhydrous ethanol of 1:5:2, dry and granulate, control the particle size to 100 mesh, put the granules into the molding mold and dry press to obtain the green body.

[0081] Step 4: The green body obtained in Step 4 is sintered at 1330℃ for 7 hours and then annealed at 850℃ for 4 hours to obtain the final microwave dielectric ceramic material, denoted as (R4)2BaZnO5.

[0082] Example 5

[0083] Step 1: Prepare raw materials Y2O3, BaCO3, ZnO, basic magnesium carbonate, Nd2O3, Eu2O3, Gd2O3, and Yb2O3 in the following mass ratios: 5.06%, 44.24%, 17.88%, 0.44%, 7.54%, 7.89%, 8.13%, and 8.83%, respectively. Grind the resulting mixture for 6 hours using zirconia balls as the milling medium and anhydrous ethanol as the solvent, with a weight ratio of mixture:zirconia balls:anhydrous ethanol of 1:5:2, to obtain a homogeneous mixture.

[0084] Step 2: The ball-milled mixture is dried at 80°C and passed through a 100-mesh sieve to obtain a dry powder. Then, it is pre-calcined at 930°C for 4 hours to obtain a sample calcined block.

[0085] Step 3: Crush the sample block into powder, use zirconium dioxide balls as the ball milling medium and anhydrous ethanol as the solvent, grind for 2 hours according to the weight ratio of sample block: zirconium dioxide balls: anhydrous ethanol of 1:5:2, dry and granulate, control the particle size to 100 mesh, put the granules into the molding mold and dry press to obtain the green body.

[0086] Step 4: The green body obtained in Step 4 is sintered at 1350℃ for 9 hours and then annealed at 850℃ for 4 hours to obtain the final microwave dielectric ceramic material, denoted as (R5)2BaZnO5.

[0087] Example 6

[0088] Step 1: Prepare raw materials Y2O3, BaCO3, ZnO, basic magnesium carbonate, Nd2O3, Er2O3, Tm2O3, and Yb2O3 in the following mass ratios: 4.98%, 43.56%, 17.24%, 0.86%, 7.70%, 8.44%, 8.52%, and 8.70%, respectively. Grind the resulting mixture for 8 hours using zirconia balls as the milling medium and anhydrous ethanol as the solvent, with a weight ratio of mixture:zirconia balls:anhydrous ethanol of 1:5:2, to obtain a homogeneous mixture.

[0089] Step 2: The ball-milled mixture is dried at 80°C and passed through a 100-mesh sieve to obtain a dry powder. Then, it is pre-calcined at 900°C for 4 hours to obtain a sample calcined block.

[0090] Step 3: Crush the sample block into powder, use zirconium dioxide balls as the ball milling medium and anhydrous ethanol as the solvent, grind for 3 hours according to the weight ratio of sample block: zirconium dioxide balls: anhydrous ethanol of 1:5:2, dry and granulate, control the particle size to 120 mesh, put the granules into the molding mold and dry press to obtain the green body.

[0091] Step 4: The green body obtained in Step 4 is sintered at 1300℃ for 8 hours and then annealed at 850℃ for 4 hours to obtain the final microwave dielectric ceramic material, denoted as (R6)2BaZnO5.

[0092] Example 7

[0093] Step 1: Prepare raw materials Y2O3, BaCO3, ZnO, basic magnesium carbonate, Nd2O3, Gd2O3, Er2O3, and Tm2O3 in the following mass ratios: 5.03%, 43.95%, 17.04%, 1.30%, 7.49%, 8.07%, 8.52%, and 8.59%, respectively. Grind the resulting mixture for 7 hours using zirconia balls as the milling medium and anhydrous ethanol as the solvent, with a weight ratio of mixture:zirconia balls:ethanol of 1:5:2, to obtain a homogeneous mixture.

[0094] Step 2: The ball-milled mixture is dried at 80°C and passed through a 100-mesh sieve to obtain a dry powder. Then, it is pre-calcined at 990°C for 4 hours to obtain a sample calcined block.

[0095] Step 3: Crush the sample block into powder, use zirconia balls as the ball milling medium and anhydrous ethanol as the solvent, grind for 4 hours according to the weight ratio of sample block:zirconia balls:anhydrous ethanol of 1:5:2, dry and granulate, control the particle size to 120 mesh, put the granules into the molding mold and dry press to obtain the green body.

[0096] Step 4: The green body obtained in Step 4 is sintered at 1320℃ for 6 hours and then annealed at 850℃ for 4 hours to obtain the final microwave dielectric ceramic material, denoted as (R7)2BaZnO5.

[0097] Example 8

[0098] Step 1: Prepare raw materials Y2O3, BaCO3, ZnO, basic magnesium carbonate, Eu2O3, Gd2O3, Er2O3, and Yb2O3 in the following mass ratios: 5.00%, 43.69%, 16.58%, 1.72%, 7.79%, 8.03%, 8.47%, and 8.72%, respectively. Grind the resulting mixture for 6 hours using zirconia balls as the milling medium and anhydrous ethanol as the solvent, with a weight ratio of mixture:zirconia balls:anhydrous ethanol of 1:5:2, to obtain a homogeneous mixture.

[0099] Step 2: The ball-milled mixture is dried at 80°C and passed through a 100-mesh sieve to obtain a dry powder. Then, it is pre-calcined at 950°C for 4 hours to obtain a sample calcined block.

[0100] Step 3: Crush the sample block into powder, use zirconium dioxide balls as the ball milling medium and anhydrous ethanol as the solvent, grind for 3 hours according to the weight ratio of sample block: zirconium dioxide balls: anhydrous ethanol of 1:5:2, dry and granulate, control the particle size to 120 mesh, put the granules into the molding mold and dry press to obtain the green body.

[0101] Step 4: The green body obtained in Step 4 is sintered at 1280℃ for 7 hours and then annealed at 850℃ for 4 hours to obtain the final microwave dielectric ceramic material, denoted as (R8)2BaZnO5.

[0102] Table 2. Processes and microwave dielectric properties used in each embodiment.

[0103]

[0104] As can be seen from Table 2, the microwave dielectric ceramic materials of each embodiment, after testing, have a dielectric constant between 14 and 18, a high Q×f value between 30,000 and 70,000 GHz, and a τ value between 14 and 18. f The value is adjustable between -30 and -8 ppm / °C, and the resonant frequency is 8.8 to 9.6 GHz. In particular, Examples 4 and 7 simultaneously exhibit high Q×f values ​​and low τ. f Its overall performance meets the requirements for high-frequency, low-loss applications of millimeter-wave devices.

[0105] Figure 1 X-ray diffraction (XRD) patterns of Examples 1, 2, 4, 6, and 8 are shown. Analysis of the patterns reveals that the ceramic diffraction peaks in these examples are consistent with those of Y₂BaZnO₅, indicating that all lanthanide elements successfully entered the Y element positions, and Mg ions completely entered the Zn element positions, forming a solid solution. Furthermore, no secondary phases were observed in the patterns, indicating that all samples maintained an orthogonal pure-phase structure. This result demonstrates the effectiveness of the high-entropy strategy, successfully achieving effective elemental substitution without introducing secondary phases.

[0106] Figure 2 Raman spectra of Examples 2, 3, 5, 7, and 8 are shown. Analysis of these spectra reveals that the ceramics of each example exhibit similar Raman scattering spectra, and no significant Raman frequency shift was observed, indicating the successful synthesis of the solid solution material. Although the ions substituting the Y position differ significantly in properties, the phonon vibrational modes produced by these ions are very similar, without leading to the emergence of different vibrational modes. This phenomenon further verifies the homogeneity of the material, indicating that the structure and phonon vibrational properties of the material remain stable despite elemental substitution.

[0107] Figure 3 Scanning electron microscope (SEM) images of Example 3 are shown. Under the conditions of long-term sintering and subsequent annealing provided by the present invention, sufficient and uniform grain growth can be clearly observed. The grain density of the ceramic is significantly improved, and no pores were found, indicating excellent densification.

[0108] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A low-dielectric, high-entropy, high-Q microwave dielectric ceramic material, characterized in that, The chemical formula is (Y 0.2 B 0.2 C 0.2 D 0.2 E 0.2 )2BaZn 1-x Mg x O5, wherein B, C, D, and E are selected from one of the La-series rare elements, including Nd, Sm, Eu, Gd, Er, Tm, and Yb, where 0 < x < 0.

1.

2. The low-dielectric-high-entropy, high-Q microwave dielectric ceramic material according to claim 1, characterized in that, The dielectric constant of the low-dielectric, high-entropy, high-Q microwave dielectric ceramic material is 14~18, the Q×f value is between 30,000 and 70,000 GHz, and the τf value is -30~-8 ppm / ℃.

3. A method for preparing a low-dielectric, high-entropy, high-Q microwave dielectric ceramic material as described in claim 1 or 2, characterized in that, Includes the following steps: A. Mix the raw materials Mg(OH)2·4MgCO3·5H2O, yttrium oxide, barium carbonate, zinc oxide and the La-series rare element oxides according to the molar ratio of the chemical formula to obtain a mixture for later use; B. One-time ball milling: Using zirconia balls as the ball milling medium, the mixture from step A is mixed with zirconia balls and anhydrous ethanol and milled for 5-7 hours to obtain a uniformly mixed ball milling material. C. Drying and sieving: Dry the ball milling material obtained in step B and sieve it through a 100-mesh sieve to obtain dry powder; D. Pre-calcination: The dried powder obtained in step C is placed in an alumina crucible and pre-calcined to obtain pre-calcined powder; E. Secondary ball milling: The pre-calcined powder obtained in step D is subjected to a second ball milling. Zirconia balls are used as the ball milling medium. The pre-calcined powder, zirconia balls, and anhydrous ethanol are mixed and ground for 2-4 hours to obtain secondary ball milling material. F. Drying and sieving: The secondary ball milling material obtained in step E is dried and sieved through a 100-mesh sieve to obtain dried powder; G. Granulation and molding: The dried powder obtained in step F is mixed with polyvinyl alcohol aqueous solution and then granulated. The granulation size is controlled at 80~100 mesh. The granules are placed in a molding die and dry-pressed to obtain a green body. H. Sintering: The green blank obtained in step G is placed in a sintering furnace and sintered and annealed to obtain a low dielectric high entropy high Q value microwave dielectric ceramic material.

4. The preparation method according to claim 3, characterized in that, In step B, the mass ratio of the mixture, zirconium dioxide balls and anhydrous ethanol is 1:(5~7):(2~4).

5. The preparation method according to claim 3, characterized in that, In step D, the pre-firing temperature is 900~1000℃, and the pre-firing time is 3~5 hours.

6. The preparation method according to claim 3, characterized in that, In step E, the mass ratio of the pre-calcined powder, zirconium dioxide balls, and anhydrous ethanol is 1:(3~5):(1~2).

7. The preparation method according to claim 3, characterized in that, In step H, the sintering furnace is heated at a rate of 3-5 °C / min and sintered at 1250-1350 °C for 6-10 hours, then cooled to 850 °C at a rate of 3 °C / min and annealed for 4 hours to obtain a low-dielectric, high-entropy, high-Q microwave dielectric ceramic material.

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