A microwave dielectric ceramic material and its application

Abstract

This invention belongs to the field of microwave dielectric ceramics technology, and discloses a microwave dielectric ceramic material and its application, specifically the application of the microwave dielectric ceramic material as an LTCC material. The chemical formula of the microwave dielectric ceramic material satisfies Ba... x Sr 1‑x (Cu y Mg 1‑y The microwave dielectric ceramic material has the following properties: Ba2Ge2O7, where 0.7 ≤ x ≤ 1 and 0.7 ≤ y ≤ 1; the co-firing temperature of this microwave dielectric ceramic material does not exceed 950℃; or, the chemical formula of the microwave dielectric ceramic material satisfies Ba2O7. x Sr 1‑x (Cu z Co 1‑z )2Ge2O7, where 0≤x≤1; when x=0, 0≤z≤1; when 0

Description

Technical Field

[0001] This invention belongs to the field of microwave dielectric ceramics technology, and more specifically, relates to a microwave dielectric ceramic material and its application, especially for microwave dielectric ceramic materials with BaCu2Ge2O7 as the main crystal phase, which can be used as low-temperature sintered LTCC materials. Background Technology

[0002] Microwave dielectric ceramics refer to ceramic materials used as dielectrics in microwave frequency bands (300MHz~300GHz) circuits. With the continuous development of communication technology, the applied microwave frequency bands are constantly increasing. The development of the Internet of Things (IoT) demands higher signal transmission quality and faster signal transmission rates. Dielectric materials with low relative permittivity can significantly improve signal transmission rates and quality, and reduce heat loss generated during device operation at high frequencies. Existing technologies have successfully prepared BaCu2Ge2O7 single crystals, primarily for applications based on weak ferromagnetism.

[0003] Low-Temperature Co-fired Ceramics (LTCC) technology encapsulates electronic components within a ceramic substrate using a multilayer substrate, while simultaneously co-firing the ceramic with a metal conductor. Considering all factors, Ag (melting point: 961℃) is commonly used as the metal electrode for co-firing, requiring the sintering temperature of the LTCC ceramic to be below 950℃. Its unique multilayer sintering process improves the reliability of components at high frequencies. LTCC technology has facilitated the rapid development of microwave components in terms of modularity, miniaturization, and multifunctionality.

[0004] Currently, due to the high sintering temperature of microwave ceramics, sintering aids such as glass, oxides, and fluorides are typically added to lower the sintering temperature to below 950℃. However, this process introduces a second phase, such as a glass phase. In the high-frequency band of microwaves, this leads to increased dielectric loss. To meet the requirements of materials in high-frequency microwave communication applications, it is crucial to prepare a low-relative-permittivity, low-loss LTCC microwave dielectric ceramic. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a microwave dielectric ceramic material and its applications. By improving the material composition, a BaCu2Ge2O7-based microwave dielectric ceramic is obtained, significantly expanding the range of microwave dielectric ceramic materials. Furthermore, microwave dielectric ceramic materials with BaCu2Ge2O7 as the main crystal phase are particularly suitable as low-dielectric (i.e., low relative permittivity) LTCC materials, applicable to the fabrication of dielectric resonators, microwave antennas, filters, and other devices in LTCC (Low Temperature Co-fired Ceramic Technology) and millimeter-wave communication applications. This invention greatly broadens the selection range of low relative permittivity LTCC microwave dielectric ceramic materials.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided an application of a microwave dielectric ceramic material as an LTCC material, wherein the chemical formula of the microwave dielectric ceramic material satisfies Ba 1-x , 1-z ,

[0012] , 1-x , 1-y , , 1-x , ,

[0011] , , 1-y , x , y , x , , z , x , y ,

[0010] ,

[0009] Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0.7 ≤ x ≤ 1 and 0.7 ≤ y ≤ 1; the co-firing temperature of the microwave dielectric ceramic material does not exceed 950 °C;

[0007] Alternatively, the chemical formula of the microwave dielectric ceramic material satisfies Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0 ≤ x ≤ 1; when x = 0, 0 ≤ z ≤ 1; when 0 < x ≤ 1, 0.7 ≤ z ≤ 1; the co-firing temperature of the microwave dielectric ceramic material does not exceed 950 °C.

[0008] As a further preference of the present invention, the co-firing temperature is 850 °C to 950 °C.

[0009] As a further preference of the present invention, the microwave dielectric ceramic material is obtained by first weighing raw materials of BaCO3, SrCO3, CuO, MgO and GeO2 according to the nominal stoichiometric ratio of each cation element in Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7 and mixing them evenly, and then sintering at a temperature of 850 °C to 950 °C;

[0010] Alternatively, the microwave dielectric ceramic material is obtained by first weighing raw materials of BaCO3, SrCO3, CuO, CoO and GeO2 according to the nominal stoichiometric ratio of each cation element in Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7 and mixing them evenly, and then sintering at a temperature of 850 °C to 950 °C.

[0011] According to another aspect of the present invention, the present invention provides an application of a microwave dielectric ceramic material as a microwave dielectric material, wherein the chemical formula of the microwave dielectric ceramic material satisfies Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1;

[0012] Alternatively, the chemical formula of the microwave dielectric ceramic material satisfies Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0≤x≤1, 0≤z≤1.

[0013] As a further preferred embodiment of the present invention, the microwave dielectric ceramic material has the chemical formula Ba. x Sr 1-x (Cu y Mg 1-y The microwave dielectric ceramic material, 2Ge₂O₇, has the following properties: 0.7 ≤ x ≤ 1, 0.3 ≤ y ≤ 1. It has a relative permittivity of 8–10.1, a quality factor Q×f of 45000–85000 GHz, and a resonant frequency temperature coefficient of -25 ppm / ℃ ≤ τ. f ≤-10ppm / ℃;

[0014] The chemical formula of microwave dielectric ceramic material is Ba. x Sr 1-x (Cu z Co 1-z The microwave dielectric ceramic material, 2Ge₂O₇, has the following properties: 0.70 ≤ x ≤ 1, 0.7 ≤ z ≤ 1. It has a relative permittivity of 8–10, a quality factor Q×f of 45000–85000 GHz, and a resonant frequency temperature coefficient of -22 ppm / ℃ ≤ τ. f ≤-10ppm / ℃;

[0015] Alternatively, the microwave dielectric ceramic material has the chemical formula BaCu2Ge2O7, a relative permittivity of 9–10.1, a quality factor Q×f of 45000–65000 GHz, and a resonant frequency temperature coefficient of -20 ppm / ℃ ≤ τ. f ≤-10ppm / ℃.

[0016] According to another aspect of the invention, a microwave dielectric ceramic material is provided, characterized in that the chemical formula of the microwave dielectric ceramic material satisfies Ba... x Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0≤x≤1, 0≤y≤1, and x and y cannot be equal to 1 at the same time;

[0017] Alternatively, the chemical formula of the microwave dielectric ceramic material satisfies Ba x Sr 1-x (Cu z Co 1-z)2Ge2O7, where 0 ≤ x ≤ 1, 0 ≤ z ≤ 1, and x and z cannot be equal to 1 simultaneously.

[0018] According to another aspect of the present invention, the present invention provides a method for preparing the above-mentioned microwave dielectric ceramic material, which is characterized by including the following steps:

[0019] (S1) Weigh raw materials of BaCO3, SrCO3, CuO, MgO, and GeO2 according to the nominal stoichiometric ratio of each cation element in Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7. Mix these raw materials and conduct wet ball milling treatment. After ball milling, dry them and then perform pre-sintering to obtain pre-sintered ceramic powder;

[0020] Alternatively, weigh raw materials of BaCO3, SrCO3, CuO, CoO, and GeO2 according to the nominal stoichiometric ratio of each cation element in Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7. Mix these raw materials and conduct wet ball milling treatment. After ball milling, dry them and then perform pre-sintering to obtain pre-sintered ceramic powder;

[0021] (S2) For the pre-sintered ceramic powder obtained in step (S1), conduct wet ball milling again, dry it after ball milling, then add a binder for granulation, press into a sheet and degrease, and then perform sintering to obtain the microwave dielectric ceramic material.

[0022] As a further preference of the present invention, the microwave dielectric ceramic material is Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0.7 ≤ x ≤ 1, 0.7 ≤ y ≤ 1; or it is Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0 ≤ x ≤ 1; when x = 0, 0 ≤ z ≤ 1; when 0 < x ≤ 1, 0.7 ≤ z ≤ 1;

[0023] In step (S​​​

[0025] As a further preference of the present invention, the microwave dielectric ceramic material is Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0 ≤ x < 0.70 and 0 ≤ y ≤ 1, or 0 ≤ x ≤ 1 and 0 ≤ y < 0.7; or it is Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0 < x ≤ 1 and 0 ≤ z < 0.7;

[0026] In the step (S1), the temperature of the pre-sintering is 850°C to 1000°C, and the pre-sintering duration is 6 to 12 hours;

[0027] In the step (S2), the tablet pressing is carried out at 100 to 150 MPa to form a green body; the debinding temperature is 500°C to 600°C, and the debinding time is 1 to 2 hours; the sintering temperature is 1000°C to 1150°C, and the sintering time is 3 to 4 hours.

[0028] As a further preference of the present invention, in the step (S2), the binder is PVA; after adding PVA, the mass fraction of PVA preferably accounts for 5wt% to 7wt%;

[0029] In the steps (S1) and (S2), the wet ball milling is carried out using deionized water as the liquid medium; the ball milling time is 4 to 8 hours.

[0030] Through the above technical solutions conceived by the present invention, compared with the prior art, the present invention obtains BaCu2Ge2O7-based microwave dielectric ceramics, greatly expanding the types of microwave dielectric ceramic materials. Different from the prior art that applies BaCu2Ge2O7 single crystals to the magnetic aspect, the present invention first uses them as microwave dielectric ceramics, showing good relative dielectric constant, quality factor, and resonant frequency temperature coefficient. ​​​​​​​​​​​​​​​​​)2Ge2O7(0 ≤ x ≤ 1; when x = 0, 0 ≤ z ≤ 1; when 0 < x ≤ 1, 0.7 ≤ z ≤ 1), especially can be used as LTCC material, and its sintering temperature is below 950 °C (that is, Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7, Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7 compounds have the advantages that the porcelain-forming temperature does not exceed 950 °C), no sintering aids are needed, and the sintering temperature can be lower than the co-firing temperature of Ag electrodes (950 °C), etc.; and, in addition to being able to co-fire with electrodes such as Ag as LTCC materials, they also maintain excellent microwave properties.

[0032] Taking undoped BaCu2Ge2O7 as an example, the relative dielectric constant of this microwave dielectric ceramic is 8.2 - 10.1, the relative dielectric constant is low, the quality factor is 45000 - 65000 GHz, and the resonant frequency temperature coefficient is -30 ppm / °C ≤ τ f ≤ -5 ppm / °C, belonging to low-dielectric LTCC materials. For microwave dielectric ceramic materials, the lower the relative dielectric constant, the more beneficial it is to improve the signal transmission rate, signal transmission quality, and reduce the heat loss generated during the operation of devices in the high-frequency band. And, this material has a high quality factor and is very suitable for use as an LTCC material substrate

[0033] The preparation method of the BaCu2Ge2O7-based microwave dielectric ceramic obtained in this invention is simple and convenient. Still taking BaCu2Ge2O7 as an example, it can be prepared by the solid-phase reaction method to obtain a BaCu2Ge2O7 material with an orthorhombic crystal structure (as shown later Figure 2 ). This microwave dielectric ceramic is a low-dielectric microwave dielectric ceramic, with a relative dielectric constant of 8,2 - 10.1, a sintering temperature range of 850 °C - 950 °C, lower than the co-firing temperature of silver electrodes ({{950}} °C). It has low loss (Q×f = 45000 - 65000 GHz), and a near-zero resonant frequency temperature coefficient (-30 ppm / °C ≤ τ f ≤ -5 ppm / °C). And further through ion substitution, Sr 2+ substitutes for Ba[[ID=--]] 2+ Mg 2+ or Co 2+ substitutes for Cu 2+ , which can adjust the sintering temperature, quality factor, and resonant frequency temperature coefficient of the material to meet different requirements. And, when the Sr 2+ doping ratio (that is, the Sr:(Ba + Sr) molar ratio) does not exceed 30 atom% and Mg2+ The doping ratio (i.e., the molar ratio of Mg:(Cu + Mg)) does not exceed 30 atom%, or when Sr 2+ the doping ratio is 100 atom% (i.e., no Ba element) and Cu 2+ and Co 2+ are in any ratio, or when Sr 2+ the doping ratio is greater than or equal to 0, less than 100 atom% and Co 2+ the doping ratio (i.e., the molar ratio of Co:(Cu + Co)) does not exceed 30 atom%, the doped polycrystalline microwave dielectric ceramic material still has a low sintering temperature and can be particularly used as a LTCC material for low-temperature sintering.

[0034] For LTCC materials with low-temperature sintering, during preparation, particularly, BaCO3, CuO, GeO2, etc. can be used as raw materials and synthesized by the solid-phase reaction method. Since the sintering temperature does not exceed 950 °C, the preparation process is simple, there is no pollution to the environment, and the operation process is simple. Taking the synthesis of BaCu2Ge2O7 microwave dielectric ceramic material as an example, BaCO3, CuO and GeO2 can be used as raw materials and synthesized by the solid-phase reaction method.

[0035] Generally speaking, the present invention can achieve the following beneficial effects:

[0036] (1) The present invention uses compounds with the chemical formula Ba[[ID=2l]] x Sr 1-x (Cu y Mg 1-y )2Ge2O7 (0.70 ≤ x ≤ 1, 0.7 ≤ y ≤ 1), Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7 (when x = 0, 0 ≤ z ≤ 1; when 0 < x ≤ 1, 0.7 ≤ z ≤ 1) to prepare microwave dielectric ceramic materials and LTCC materials. This new type of microwave dielectric ceramic has advantages such as a low relative dielectric constant, excellent quality factor, a wide sintering region, a single phase structure, a low sintering temperature, and a near-zero temperature coefficient of resonant frequency.

[0037] [[ID=3l]](2) The present invention provides a LTCC material that simultaneously has a low relative dielectric constant, excellent microwave dielectric properties, does not require the addition of a sintering aid, has a sintering temperature not exceeding 950 °C, and is prepared by the LTCC preparation process. The preparation process of the present invention is simple, has no pollution to the environment, and the operation process is simple. It is an ideal LTCC preparation process. Brief Description of the Drawings

[0038] Figure 1Ba obtained in Example 16 of this invention with different values ​​of x and a sintering temperature of 875°C. x Sr 1- x A comparison of X-ray diffraction data of Cu2Ge2O7 material with the standard card of BaCu2Ge2O7 material.

[0039] Figure 2 This is a schematic diagram of the crystal structure of BaCu2Ge2O7 material.

[0040] Figure 3 Yes x Sr 1-x The trend of cell parameters of Cu2Ge2O7 single-phase solid solution with the value of (1-x). Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0042] The present invention will be further illustrated by the following examples.

[0043]

[0044] Example 1:

[0045] Ba 0.95 Sr 0.05 Cu2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0046] (1) Weighing and Batching: Weigh the raw materials (BaCO3, SrCO3, CuO, and GeO2, all with a purity greater than 99.9%) that have undergone calcination and drying pretreatment, according to the chemical formula Ba 0.95 Sr 0.05 Weigh and mix the ingredients according to the nominal stoichiometric ratio of each cation element in Cu2Ge2O7.

[0047] (2) First ball milling: The weighed raw material is transferred into a ball mill jar, and deionized water is used as the liquid medium and zirconium dioxide grinding beads are used as the grinding medium. The mixture is ball milled for 6 hours.

[0048] (3) Pre-calcination: The slurry after ball milling is dried at 80°C for 12 hours. The dried powder is then ground through a 40-mesh standard sieve and pre-calcined at 875°C for 6 hours at a heating rate of 5°C per minute, followed by furnace cooling.

[0049] (4) Secondary ball milling: The pre-calcined powder is ball milled a second time, and the specific process is the same as the primary ball milling.

[0050] (5) Drying, granulation and molding: The slurry after secondary ball milling is dried at 80°C for 12 hours. Using 5% PVA solution as a binder, it is thoroughly mixed and passed through a 40-mesh standard sieve. Then, the granulated powder is poured into a steel mold and made into a green body with a diameter of about 12 mm and a height of about 5 mm under a pressure of 100 MPa to 150 MPa.

[0051] (6) Debinding and sintering: The green body was debinded at 550℃ for 2 hours, and then heated to 875℃, 900℃, 925℃ and 950℃ respectively at a heating rate of 5℃ per minute for 4 hours. After that, it was cooled to room temperature with the furnace to obtain microwave dielectric ceramic samples, which were recorded as sample 1-1, sample 1-2, sample 1-3 and sample 1-4 respectively.

[0052] Taking sample 1-1 as an example, the relative permittivity is 9.38±0.7, Q×f is 65810±5000GHz, and the temperature coefficient of resonant frequency is -13.5±2ppm / ℃.

[0053] Example 2:

[0054] Ba 0.9 Sr 0.1 Cu2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0055] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the proportions of the raw materials in step (1) are based on the chemical formula Ba. 0.9 Sr 0.1 The nominal stoichiometric ratios of each cation element in Cu2Ge2O7 were weighed. The pre-calcination temperature in step (3) was 850℃.

[0056] Similarly, the four samples obtained in step (6) are respectively named sample 2-1, sample 2-2, sample 2-3, and sample 2-4.

[0057] Taking sample 2-1 as an example, the relative permittivity is 9.33±0.7, Q×f is 72750±5000GHz, and the resonant frequency temperature is -15.6ppm±2 / ℃.

[0058] Example 3:

[0059] Ba 0.85 Sr 0.15 Cu2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0060] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the proportions of the raw materials in step (1) are based on the chemical formula Ba. 0.85 Sr 0.15 Weigh the nominal stoichiometric ratio of each cation element in Cu2Ge2O7; the pre-calcination temperature in step (3) is 850℃.

[0061] Similarly, the four samples obtained in step (6) are respectively named sample 3-1, sample 3-2, sample 3-3, and sample 3-4.

[0062] Taking sample 3-1 as an example, the relative permittivity is 9.26±0.7, Q×f is 85660±5000GHz, and the temperature coefficient of resonant frequency is -15.2±2ppm / ℃.

[0063] Example 4:

[0064] BaCu 1.8 Mg 0.2 Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0065] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the raw materials in step (1) are BaCO3, MgO, CuO, and GeO2 (all with a purity greater than 99.9%), according to the chemical formula Ba(CuO) 0.9 Mg 0.1 Weigh and mix the ingredients according to the nominal stoichiometric ratio of each cation element in 2Ge2O7. The pre-calcination temperature in step (3) is 850℃.

[0066] Similarly, the four samples obtained in step (6) are respectively named sample 4-1, sample 4-2, sample 4-3, and sample 4-4.

[0067] Taking sample 4-3 as an example, the relative permittivity is 9.32±0.7, Q×f is 71270±5000GHz, and the temperature coefficient of resonant frequency is -10.4±2ppm / ℃.

[0068] Example 5:

[0069] BaCu 1.6 Mg 0.4 Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0070] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the raw materials in step (1) are BaCO3, MgO, CuO, and GeO2 (all with a purity greater than 99.9%), according to the chemical formula Ba(CuO) 0.8 Mg0.2 Weigh and mix the ingredients according to the nominal stoichiometric ratio of each cation element in 2Ge2O7. The pre-calcination temperature in step (3) is 850℃.

[0071] Similarly, the four samples obtained in step (6) are respectively named sample 5-1, sample 5-2, sample 5-3, and sample 5-4.

[0072] Taking sample 5-4 as an example, the relative permittivity is 9.36±0.7, Q×f is 67246±5000GHz, and the temperature coefficient of resonant frequency is -10.2±2ppm / ℃.

[0073] Example 6:

[0074] BaCo2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0075] Steps (2), (4), and (5) are the same as in Example 1, except that in this example, the raw materials in step (1) are BaCO3, CoO, and GeO2 (all with a purity greater than 99.9%), and are weighed and prepared according to the nominal stoichiometric ratio of each cation element in the chemical formula BaCo2Ge2O7. The pre-firing temperature in step (3) is 1100℃. The sintering temperatures in step (6) are 1050℃, 1075℃, 1100℃, and 1125℃, respectively.

[0076] Similarly, the four samples obtained in step (6) are respectively named sample 6-1, sample 6-2, sample 6-3 and sample 6-4.

[0077] Taking sample 6-3 as an example, the relative permittivity is 9.09±0.7, Q×f is 35420±5000GHz, and the temperature coefficient of resonant frequency is -15.7±2ppm / ℃.

[0078] Example 7:

[0079] SrCo2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0080] Steps (2), (3), (4), and (5) are the same as in Example 1, except that in this example, the raw materials in step (1) are SrCO3, CoO, and GeO2 (all with a purity greater than 99.9%), and are weighed and prepared according to the nominal stoichiometric ratio of each cation element in the chemical formula SrCo2Ge2O7. The sintering temperatures in step (6) are 900℃, 925℃, and 950℃, and the four samples obtained are recorded as Sample 7-1, Sample 7-2, and Sample 7-3, respectively.

[0081] Taking sample 7-3 as an example, the relative permittivity is 8.95±0.7, Q×f is 32660±5000GHz, and the temperature coefficient of resonant frequency is -21.7±2ppm / ℃.

[0082] Example 8:

[0083] BaMg2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0084] Steps (2), (4), and (5) are the same as in Example 1, except that in this example, the raw materials in step (1) are BaCO3, MgO, and GeO2 (all with a purity greater than 99.9%), and are weighed and prepared according to the nominal stoichiometric ratio of each cation element in the chemical formula BaMg2Ge2O7. The pre-firing temperature in step (3) is 1025℃. The sintering temperatures in step (6) are 1075℃, 1100℃, 1125℃, and 1150℃, respectively, and the resulting samples are recorded as Sample 8-1, Sample 8-2, Sample 8-3, and Sample 8-4, respectively.

[0085] Taking sample 8-2 as an example, the relative permittivity is 8.32±0.7, Q×f is 58351±5000GHz, and the temperature coefficient of resonant frequency is -24.5±2ppm / ℃.

[0086] Example 9:

[0087] Ba 0.8 Sr 0.2 Cu2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0088] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the proportions of the raw materials in step (1) are based on the chemical formula Ba. 0.8 Sr 0.2 The nominal stoichiometric ratios of each cation element in Cu2Ge2O7 were weighed. The pre-calcination temperature in step (3) was 850℃.

[0089] Similarly, the four samples obtained in step (6) are respectively named sample 9-1, sample 9-2, sample 9-3 and sample 9-4.

[0090] Taking sample 9-1 as an example, the relative permittivity is 9.33±0.7, Q×f is 65820±5000GHz, and the resonant frequency temperature is -13.3±2ppm / ℃.

[0091] Example 10:

[0092] Ba 0.75 Sr 0.25Cu2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0093] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the proportions of the raw materials in step (1) are based on the chemical formula Ba. 0.75 Sr 0.25 The nominal stoichiometric ratios of each cation element in Cu2Ge2O7 were weighed. The pre-calcination temperature in step (3) was 850℃.

[0094] Similarly, the four samples obtained in step (6) are respectively named sample 10-1, sample 10-2, sample 10-3, and sample 10-4.

[0095] Taking sample 10-1 as an example, the relative permittivity is 9.48±0.7, Q×f is 62470±5000GHz, and the resonant frequency temperature is -11.5±2ppm / ℃.

[0096] Example 11:

[0097] BaCu2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0098] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the raw materials in step (1) are weighed according to the nominal stoichiometric ratio of each cation element in the chemical formula BaCu2Ge2O7. The pre-calcination temperature in step (3) is 850°C.

[0099] Similarly, the four samples obtained in step (6) are respectively named sample 11-1, sample 11-2, sample 11-3, and sample 11-4.

[0100] Taking sample 11-1 as an example, the relative permittivity is 9.38±0.7, Q×f is 65810±5000GHz, and the resonant frequency temperature is -11.8±2ppm / ℃.

[0101] Example 12:

[0102] BaCu 1.8 Co 0.2 Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0103] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the ratio of raw materials in step (1) is based on the chemical formula BaCu. 1.8 Co 0.2 The nominal stoichiometric ratios of the cations in Ge2O7 were weighed. The pre-calcination temperature in step (3) was 850℃.

[0104] Similarly, the four samples obtained in step (6) are respectively named sample 12-1, sample 12-2, sample 12-3, and sample 12-4.

[0105] Taking sample 12-1 as an example, the relative permittivity is 9.35±0.7, Q×f is 70356±5000GHz, and the resonant frequency temperature is -13.4±2ppm / ℃.

[0106] Example 13:

[0107] BaCu 1.6 Co 0.4 Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0108] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the ratio of raw materials in step (1) is based on the chemical formula BaCu. 1.6 Co 0.4 The nominal stoichiometric ratios of the cations in Ge2O7 were weighed. The pre-calcination temperature in step (3) was 850℃.

[0109] Similarly, the four samples obtained in step (6) are respectively named sample 13-1, sample 13-2, sample 13-3 and sample 13-4.

[0110] Taking sample 13-1 as an example, the relative permittivity is 9.36±0.7, Q×f is 68246±5000GHz, and the resonant frequency temperature is -16.2±2ppm / ℃.

[0111] Example 14:

[0112] BaCu 1.4 Co 0.6 Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0113] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the ratio of raw materials in step (1) is based on the chemical formula BaCu. 1.4 Co 0.6 The nominal stoichiometric ratios of the cations in Ge2O7 were weighed. The pre-calcination temperature in step (3) was 850℃.

[0114] Similarly, the four samples obtained in step (6) are respectively named sample 14-1, sample 14-2, sample 14-3, and sample 14-4.

[0115] Taking sample 14-1 as an example, the relative permittivity is 9.31±0.7, Q×f is 60364±5000GHz, and the resonant frequency temperature is -18.9±2ppm / ℃.

[0116] Example 15:

[0117] SrCu2Ge2O7 microwave dielectric ceramic and its preparation method, the preparation process includes the following steps:

[0118] Steps (2), (4), (5), and (6) are the same as in Example 1, except that in this example, the raw materials in step (1) are weighed according to the nominal stoichiometric ratio of each cation element in the chemical formula SrCu2Ge2O7. The pre-calcination temperature in step (3) is 850°C.

[0119] Similarly, the four samples obtained in step (6) are respectively named sample 15-1, sample 15-2, sample 15-3 and sample 15-4.

[0120] Taking sample 15-1 as an example, the relative permittivity is 9.26±0.7, Q×f is 23940±5000GHz, and the resonant frequency temperature is -7.02±2ppm / ℃.

[0121] Example 16:

[0122] This embodiment discusses different Sr element doping levels (i.e., Ba). x Sr 1-x (Cu y Mg 1-y The effect of different (1-x) values ​​on the material properties of 2Ge2O7, where x varies in increments of 0.05 within the range of [0.65, 1.00].

[0123] The preparation process is as follows:

[0124] (1) Weighing and batching: Weigh and batch the raw materials BaCO3, SrCO3, CuO and GeO2 (all with a purity greater than 99.9%) that have undergone calcination and drying pretreatment according to the nominal stoichiometric ratio of each cation element in the chemical formula.

[0125] (2) First ball milling: The weighed raw material is transferred into a ball mill jar, and deionized water is used as the liquid medium and zirconium dioxide grinding beads are used as the grinding medium. The mixture is ball milled for 6 hours.

[0126] (3) Pre-calcination: The slurry after ball milling is dried at 80°C for 12 hours. The dried powder is then ground through a 40-mesh standard sieve and pre-calcined at 875°C for 6 hours at a heating rate of 5°C per minute, followed by furnace cooling.

[0127] (4) Secondary ball milling: The pre-calcined powder is ball milled a second time, and the specific process is the same as the primary ball milling.

[0128] (5) Drying, granulation and molding: The slurry after secondary ball milling is dried at 80°C for 12 hours. Using 5% PVA solution as a binder, it is thoroughly mixed and passed through a 40-mesh standard sieve. Then, the granulated powder is poured into a steel mold and made into a green body with a diameter of about 12 mm and a height of about 5 mm under a pressure of 100 MPa to 150 MPa.

[0129] (6) Debinding and sintering: The green body was debinded at 550℃ for 2 hours, and then sintered at 875℃ for 4 hours at a heating rate of 5℃ per minute. After that, it was cooled to room temperature in the furnace to obtain microwave dielectric ceramic samples.

[0130] The Ba obtained in this embodiment x Sr 1-x The Cu2Ge2O7 sample was characterized by XRD, and the results are as follows: Figure 1 As shown. By Figure 1 As can be seen, when the Ba:(Ba+Sr) molar ratio x is in the range of 0.7 to 1, the diffraction peaks of all samples are in perfect agreement with the standard card of tetragonal (Pnma)BaCu2Ge2O7, showing no signs of impurity phases or phase transitions. This observation confirms that Sr... 2+ Right 2 + The successful substitution resulted in the formation of a single-phase solid solution, Ba. x Sr 1-x Cu2Ge2O7. However, when x = 0.65, a small amount of impurity phase appeared. Therefore, Ba x Sr 1-x The solid solution range of Cu2Ge2O7 is between x = 0.65 and 0.7.

[0131] according to Figure 1 The XRD pattern shown shows the refined lattice parameters. Figure 3 As shown. Figure 3 As shown, the lattice parameters a, b, and c, and the volume V, change linearly with different values ​​of (1-x). The underlying mechanism is speculated to be: when the coordination number is 8, Ba... 2+ and Sr 2+ The ionic radii are respectively and Due to Sr 2+ The radius of the ion is smaller than that of Ba. 2+ The ions, lattice parameters a, b, and c decrease linearly with increasing (1-x), causing the lattice volume V to decrease from... monotonically decrease to

[0132] Further on Figure 3 After linear fitting of the lattice parameters a, b, and c in the model, the slopes of the corresponding fitted curves are respectively... and When Sr 2+ Replace Ba 2+ The significant anisotropy of the shrinkage rates of lattice parameters a and c relative to b indicates that there is significant anisotropy in the ion distribution in different directions of the lattice.

[0133] As can be seen, the dielectric constant of the microwave dielectric ceramic materials in Examples 1-15 is 8-10, the quality factor Q×f is up to 85000 GHz, and the temperature coefficient of resonant frequency τ is... f The concentration is -25ppm / ℃ to -5ppm / ℃. Among these, Ba in preferred embodiments 1-5 and 8-10 is preferred. x Sr 1-x Cu2Ge2O7 and Ba(Cu y Mg 1-y The 2Ge2O7 microwave dielectric ceramic material can meet the requirements of new LTCC microwave dielectric devices. Furthermore, the minimum sintering temperature of the prepared ceramic material is 875℃, and the maximum sintering temperature is 950℃, which can achieve densification at low temperature.

[0134] Comparative Example 1

[0135] During the research and development process, this invention also explored different material composition systems. Their preparation processes were similar to those in Example 1, except for the target material composition (i.e., the chemical formula of the material), the corresponding raw materials and their proportions, and the calcination temperature. Specifically, the design of their target chemical formulas, calcination temperatures (ST), and the measured relative permittivity (ε) of the corresponding products were all different. r-mea The quality factor (Q×f) and the temperature coefficient of the resonant frequency are (τ). f The results are shown in the table below; it can be seen that the performance of these material systems as microwave dielectric ceramic materials is not as good as that of the above embodiments.

[0136]

[0137] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An application of a microwave dielectric ceramic material as an LTCC material, characterized in that, The chemical formula of microwave dielectric ceramic materials satisfies Ba x Sr 1-x (Cu y Mg 1-y The microwave dielectric ceramic material is 2Ge2O7, wherein 0.7≤x≤1 and 0.7≤y<1; the co-firing temperature of this material does not exceed 950℃. Alternatively, the chemical formula of the microwave dielectric ceramic material satisfies Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0 ≤ x ≤ 1; when x = 0, 0 ≤ z < 1; when 0 < x ≤ 1, 0.7 ≤ z < 1; the co-firing temperature of the microwave dielectric ceramic material does not exceed 950 °C.

2. The application as described in claim 1, characterized in that, The co-firing temperature is 850℃~950℃.

3. The application as described in claim 1, characterized in that, The microwave dielectric ceramic material is first processed according to Ba... x Sr 1-x (Cu y Mg 1-y The nominal stoichiometric ratio of each cation element in 2Ge2O7 is obtained by weighing BaCO3, SrCO3, CuO, MgO and GeO2 raw materials, mixing them evenly, and then sintering them at a temperature of 850℃~950℃. Alternatively, the microwave dielectric ceramic material is first prepared according to Ba... x Sr 1-x (Cu z Co 1-z The nominal stoichiometric ratio of each cation element in 2Ge2O7 is obtained by weighing BaCO3, SrCO3, CuO, CoO and GeO2 raw materials, mixing them evenly, and then sintering them at a temperature of 850℃~950℃.

4. An application of a microwave dielectric ceramic material as a microwave dielectric material, characterized in that, The chemical formula of microwave dielectric ceramic materials satisfies Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0≤x≤1, 0≤y<1; Alternatively, the chemical formula of the microwave dielectric ceramic material satisfies Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0≤x≤1, 0≤z<1.

5. The application as described in claim 4, characterized in that, The chemical formula of microwave dielectric ceramic material is Ba. x Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0.7≤x≤1, 0.3≤y<1, the relative permittivity of this microwave dielectric ceramic material is 8~10.1, and the quality factor is Q×f Values ​​range from 45000 to 85000 GHz, with a resonant frequency temperature coefficient of -25 ppm / ℃ ≤ τ f ≤ -10ppm / ℃; The chemical formula of microwave dielectric ceramic material is Ba. x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0.70≤x≤1, 0.7≤z<1, the relative permittivity of this microwave dielectric ceramic material is 8~10, and the quality factor is Q×f The value is 45000-85000GHz, and the temperature coefficient of the resonant frequency is -22ppm / ℃ ≤ τ. f ≤ -10ppm / ℃; Alternatively, the microwave dielectric ceramic material has the chemical formula BaCu2Ge2O7, a relative permittivity of 9–10.1, and a quality factor of [missing information]. Q×f Values ​​range from 45000 to 65000 GHz, with a resonant frequency temperature coefficient of -20 ppm / ℃ ≤ τ f ≤-10ppm / ℃.

6. A microwave dielectric ceramic material, characterized in that, The chemical formula of microwave dielectric ceramic materials satisfies Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0≤x≤1, 0≤y<1; Alternatively, the chemical formula of the microwave dielectric ceramic material satisfies Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0≤x≤1, 0≤z<1.

7. The method for preparing the microwave dielectric ceramic material according to any one of claims 1-6, characterized in that, Includes the following steps: (S1) Press Ba x Sr 1-x (Cu y Mg 1-y The nominal stoichiometric ratio of each cation element in 2Ge2O7 was determined by weighing BaCO3, SrCO3, CuO, MgO and GeO2 raw materials, mixing these raw materials and performing wet ball milling, drying after ball milling, and then pre-firing to obtain pre-fired ceramic powder. Or, according to Ba x Sr 1-x (Cu z Co 1-z The nominal stoichiometric ratio of each cation element in 2Ge2O7 was determined by weighing BaCO3, SrCO3, CuO, CoO and GeO2 raw materials, mixing these raw materials and performing wet ball milling, drying after ball milling, and then pre-firing to obtain pre-fired ceramic powder. (S2) The pre-fired ceramic powder obtained in step (S1) is subjected to wet ball milling again, dried after ball milling, then granulated by adding binder, pressed into sheets and debinded, and then sintered to obtain microwave dielectric ceramic material.

8. The preparation method according to claim 7, characterized in that, The microwave dielectric ceramic material is Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0.7 ≤ x ≤ 1 and 0.7 ≤ y < 1; or it is Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0 ≤ x ≤ 1; when x = 0, 0 ≤ z < 1; when 0 < x ≤ 1, 0.7 ≤ z < 1; In step (S1), the pre-firing temperature is 800℃~850℃, and the pre-firing time is 6~12h; In step (S2), the pressing is performed by pressing the sheet into a blank at 100-150 MPa; the glue removal temperature is 500℃-600℃ and the glue removal time is 1-2h; the sintering temperature is 850℃-950℃ and the sintering time is 3-4h.

9. The preparation method according to claim 7, characterized in that, The microwave dielectric ceramic material is Ba x Sr 1-x (Cu y Mg 1-y )2Ge2O7, where 0 ≤ x < 0.70 and 0 ≤ y < 1, or 0 ≤ x ≤ 1 and 0 ≤ y < 0.7; or it is Ba x Sr 1-x (Cu z Co 1-z )2Ge2O7, where 0 < x ≤ 1 and 0 ≤ z < <0.7; In step (S1), the pre-firing temperature is 850℃~1000℃, and the pre-firing time is 6~12h; In step (S2), the pressing is performed by pressing the sheet into a blank at 100-150 MPa; the glue removal temperature is 500℃-600℃ and the glue removal time is 1-2h; the sintering temperature is 1000℃-1150℃ and the sintering time is 3-4h.

10. The preparation method according to claim 7, characterized in that, In step (S2), the adhesive is PVA; after adding PVA, the mass fraction of PVA is 5wt% to 7wt%. In steps (S1) and (S2), deionized water is used as the liquid medium for wet ball milling; the milling time is 4-8 hours.

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