Low-dielectric molybdenum-based microwave dielectric ceramic with adjustable wide-range microwave dielectric property and preparation method of low-dielectric molybdenum-based microwave dielectric ceramic

Abstract

The invention relates to the technical field of ceramic materials, in particular to low-dielectric molybdenum-based microwave dielectric ceramic with adjustable wide-range microwave dielectric property and a preparation method thereof, the chemical formula of the low-dielectric molybdenum-based microwave dielectric ceramic is Ca1-xEuxMo1-xNbxO4 (x is greater than or equal to 0.1 and less than or equal to 0.6), and the preparation method of the low-dielectric molybdenum-based microwave dielectric ceramic comprises the following steps: taking Nb2O5, Eu2O3, CaCO3 and MoO3 as raw materials, and carrying out primary ball milling, pre-sintering, drying, secondary ball milling, drying, granulating, developing, forming and sintering to prepare the low-dielectric molybdenum-based microwave dielectric ceramic. The molybdenum-based microwave dielectric ceramic material has the advantages that the molybdenum-based microwave dielectric ceramic material is prepared from Ca0. 4Eu0. 6Mo0. 4Nb0. 6O4 and Ca0. 4Eu0. 6Mo0. 4Nb0. 6O4, the regulation range of the molybdenum-based microwave dielectric ceramic material is widened in a process temperature and component doping coordinated regulation mode, the quality factor (Q * f) value of the Ca0. 4Eu0. 6Mo0. 4Nb0. 6O4 prepared at the sintering temperature of 1400 DEG C is 82930 GHz, the dielectric constant (epsilon r) is 15.6, and the temperature coefficient of resonance Meanwhile, a substrate integrated resonant antenna is designed, the gain at the center resonant frequency (3.69 GHz) is 6.1 dBi, and the gain is S11lt; and the radiation efficiency at a-10dB region reaches 90% or more, and the operation requirement of the 5G communication technology is met.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, in particular to low-dielectric molybdenum-based microwave dielectric ceramics with adjustable wide-range microwave dielectric properties. Background Art

[0002] Microwave dielectric ceramics (MWDC) refer to ceramics used as dielectric materials in microwave frequency band (300MHz-300 GHz) circuits and perform one or more functions such as microwave waveguide, shielding and resonance. They are key basic materials in modern communication technology fields such as microwave communications, high-speed and high-frequency circuit substrates, satellite positioning and navigation systems, radar detection, etc. They are widely used as components such as resonators, filters, dielectric substrates and dielectric waveguide circuits. The rapid development of modern mobile communications has driven the rapid development of various types of microwave mobile communication terminal equipment towards miniaturization, lightweight, multifunctionality and low cost. With the deepening application of 5G technology, microwave communication technology has extended to the millimeter wave band. Microwave dielectric ceramic materials in the extremely high frequency millimeter wave band need to: 1. Have a low dielectric constant (ε r ) to increase the transmission rate of electrical signals (low dielectric constant can reduce the mutual coupling of electromagnetic signals and increase the propagation rate of electromagnetic waves); 2. High quality factor (low dielectric loss, usually requiring Q×f ≥ 30000GHz) to improve the selectivity of the device's operating frequency and reduce the device's energy conversion consumption; 3. Near-zero resonant frequency temperature coefficient (τ f ) to ensure the stability of the signal during resonance and transmission. Therefore, low dielectric and high quality factor microwave dielectric ceramic materials (dielectric constant ε r <20) has been widely explored and studied by researchers at home and abroad in recent years.

[0003] Compounds with the general formula ABO4, such as CaWO4 and CaMoO4, have attracted attention due to their applications in solid-state fuel cell cathode materials, photocatalytic and photoluminescent materials, thermal barrier coatings, and other fields. Choi et al. first reported the microwave dielectric properties of tetragonal scheelite-structured CaMoO4 ceramics (ST = 1100 ° C, ε r =10.79, Q×f=89,700GHz, τ f =-57ppm / ℃), however, its large negative τ f It cannot meet the needs of practical applications. 1-x Cd x The use of Cd in MoO4 system 2+ Replace Ca 2+ , lower the sintering temperature to 1075-900℃, but τ fThere is no significant improvement. Zheng Mupeng et al. added a certain amount of Li2MoO4 to significantly reduce the sintering temperature of CaMoO4 to 600℃, and the microwave dielectric properties were ε r =15.1, Q×f=16,122GHz, τ f =-43.8ppm / ℃, which leads to a significant decrease in the quality factor. Considering that monoclinic scheelite BiVO4 has a low sintering temperature, Zhou Di et al. tried to 3+ With V 5+ Ca in the structure 2+ and Mo 6+ Simultaneous substitution was performed and it was found that with Bi 3+ With V 5+ As the amount of substitution increases, the crystal structure always maintains the tetragonal scheelite structure, τ f The value moves rapidly in the positive direction (-44.9~+71.6ppm / ℃), and the dielectric constant also increases rapidly from 15.1 to 34.5. When x=0.34, τ f The value is close to zero (+0.1ppm / ℃), but its dielectric constant is 21.9, which is higher than 20, and the Q×f value drops significantly to 18150GHz. Hu Yongda et al. prepared CaMoO4+10wt.%CaTiO3+0.75wt.%BaCu(B2O5) by adding sintering aids. Its microwave dielectric properties are ε r =14.92, Q×f=23,034GHz, τ f =-2.03ppm / ℃. However, this method achieves the purpose of regulating microwave dielectric properties by adding sintering aids to introduce a second phase or even a third phase.

[0004] By comparing with the existing technology, it can be seen that for molybdenum-based scheelite CaMoO4, although it has a high quality factor, its τ f However, it is a large negative value. At present, there are still the following technical problems in the modification and optimization of tetragonal scheelite structure CaMoO4 ceramics:

[0005] (1) To adjust the microwave dielectric properties of tetragonal scheelite structure CaMoO4 ceramics, other ions are currently used to replace the A or B position to improve the microwave dielectric properties. However, the adjustment method is single and the range of adjustment of microwave dielectric properties is narrow. The "process temperature + component doping" synergistic adjustment method has not been disclosed to broaden the adjustment range of microwave dielectric properties of CaMoO4 ceramics.

[0006] (2) For tetragonal scheelite structure CaMoO4 ceramics, a large number of performance control strategies are used to control τ fThe value of ε is often adjusted to cause a sharp deterioration of the quality factor and a significant increase in the dielectric constant. It is impossible to adjust the modified ceramics in the desired direction (even if ε r Reduced to ε r <20, so that Q×f is not significantly reduced compared with the Q×f of CaMoO4 ceramics (Q×f=89,700GHz), and τ f tends to zero), resulting in incomplete improvement of microwave dielectric properties.

[0007] (3) Although the prior art also discloses the preparation of ε r <20, τ f The Q×f value of molybdenum-based microwave dielectric ceramics is close to zero, but it is achieved by introducing the second phase regulation, and the Q×f value is obviously low. Summary of the Invention

[0008] The purpose of the present invention is to provide a low-dielectric molybdenum-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties and a preparation method thereof, and to provide a Ca 1-x Eu x Mo 1-x Nb x O4 microwave dielectric ceramic material and preparation method thereof.

[0009] To achieve the above objectives, in a first aspect, the present invention provides a low-K Mo-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties. The chemical formula of the molybdenum-based microwave dielectric ceramic is: Ca 1-x Eu x Mo 1-x Nb x O4 (0.1≤x≤0.6), its dielectric constant range is 11.4~15.8, its quality factor range is 21950~82930GHz, τ f It is -47.7ppm / ℃~+6.0ppm / ℃.

[0010] Preferably, the chemical formula of the molybdenum-based microwave dielectric ceramic is: Ca 0.4 Eu 0.6 Mo 0.4 Nb 0.6 O4, whose dielectric constant ranges from 15.6, quality factor ranges from 82930GHz, τ f +4.0ppm / ℃.

[0011] In a second aspect, the present invention further provides a method for preparing a low-K-type molybdenum-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties. The method broadens the adjustment range by synergistically controlling the process temperature and component doping. The method is characterized in that the method comprises the following steps:

[0012] (1) Weighing Nb2O5, Eu2O3, CaCO3 and MoO3 powders to obtain raw powders;

[0013] (2) the raw powders are stirred and mixed, subjected to a first wet grinding process in a ball milling medium, and then dried. After drying, the raw powders are mixed again, subjected to a second wet grinding process in a ball milling medium, and then dried a second time to obtain a dried powder, which is pre-sintered at 1000° C. in an atmosphere for 4 hours to obtain a pre-sintered powder;

[0014] (3) Adding a binder to the pre-sintered powder to form granules, pressing and molding, and finally sintering at 1250-1450° C. in an atmosphere for 6 hours to obtain a molybdenum-based microwave dielectric ceramic.

[0015] Preferably, in step (2), the wet milling treatment time is 6 hours, and the milling medium is anhydrous ethanol.

[0016] Preferably, in step (3), the binder is a polyvinyl alcohol solution with a mass concentration of 5%, and the added mass of the binder accounts for 3% of the total mass of the original powder.

[0017] Preferably, in step (3), the sintering temperature is 1350°C.

[0018] Preferably, in step (3), the sintering temperature is 1400°C.

[0019] In the third aspect, the present invention also provides an application of low-dielectric molybdenum-based microwave dielectric ceramics, specifically a substrate-integrated resonant antenna, which includes: a dielectric resonant antenna, a substrate, a rectangular slot microstrip coupling slot, and a metal feed line. The dielectric resonant antenna is composed of Ca 0.4 Eu 0.6 Mo 0.4 Nb 0.6 Made of O4 microwave dielectric ceramic material, a substrate is tightly secured beneath the dielectric resonant antenna, with the antenna positioned directly above it. A rectangular slot is located in the center of the substrate, serving as a microstrip coupling slot that isolates the feed network at the bottom of the substrate, preventing coupling losses. A layer of copper is coated on the upper surface of the substrate as a metal ground, while a metal feed line is located on the lower surface, serving as a conductive conductor.

[0020] Preferably, the center frequency of the dielectric resonant antenna is 4.23 GHz, and it has a cylindrical structure with a height of 8.07 mm and a diameter of 16.98 mm. The substrate is a square Arlon CLTE-XT with a dielectric constant of 2.94, a loss tangent of 0.0012, a length of 50 mm, a width of 50 mm, and a thickness of 0.76 mm. The rectangular slot has a size of 7.0 mm in length and 2.3 mm in width. The metal feed line has a length of 29.4 mm and a width of 1.91 mm. One end of the metal feed line is flush with the edge of the substrate, and the other end extends into the middle of the substrate.

[0021] Beneficial effects

[0022] (1) The molybdenum-based microwave dielectric ceramic material prepared by the present invention has a high quality factor (Q×f) value (21950~82930GHz), a low dielectric constant (ε r )11.4~15.8, resonant frequency temperature coefficient (τ f ) value can be adjusted between -47.7ppm / ℃ and +6.0ppm / ℃. Through the coordinated control method of "process temperature + component doping", the adjustment range of molybdenum-based microwave dielectric ceramic materials is broadened.

[0023] (2) The preparation method of the present invention does not require the addition of modifying materials, and the obtained molybdenum-based Ca 1-x Eu x Mo 1-x Nb x O4 (0.1≤x≤0.6) microwave dielectric ceramic material is a single pure phase. Due to its single composition, it ensures a high quality factor and low dielectric constant, which is beneficial to the quality factor (Q×f) value and dielectric constant (ε r ) and the resonant frequency temperature coefficient (τ f ) for precise control.

[0024] (3) The microwave dielectric ceramics prepared by the method of the present invention are not easy to deliquesce and have a stable crystal structure, and are suitable for preparing microwave devices in various environments.

[0025] (4) The substrate integrated resonant antenna designed by the present invention utilizes Ca 0.4 Eu 0.6 Mo 0.4 Nb 0.6 O4 microwave dielectric ceramics have a good quality factor (Q×f) value and a low dielectric constant (ε r ), the resonant frequency temperature coefficient approaches zero, and the designed substrate integrated resonant antenna has a gain of 6.1dBi at the center resonant frequency (3.69GHz). 11 The radiation efficiency in the <-10dB area reaches over 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 It is a schematic flow chart of the steps of the preparation method of the low-dielectric Mo-based microwave dielectric ceramic material with adjustable wide-range microwave dielectric properties prepared in Examples 1-10 of the present invention.

[0028] Figure 2 The low-dielectric Mo-based microwave dielectric ceramic Ca with adjustable wide-range microwave dielectric properties prepared in Examples 1-6 of the present invention 1-x Eu x Mo 1-x Nb x X-ray diffraction (XRD) patterns of O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6).

[0029] Figure 3 The low-dielectric Mo-based microwave dielectric ceramic Ca with adjustable wide-range microwave dielectric properties prepared in Examples 1-6 of the present invention 1-x Eu x Mo 1-x Nb x XRD structure refinement patterns of O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) (a: x = 0.1; b: x = 0.2; c: x = 0.3; d: x = 0.4; e: x = 0.5).

[0030] Figure 4 The low-dielectric Mo-based microwave dielectric ceramic Ca with adjustable wide-range microwave dielectric properties prepared in Examples 1, 3 and 5 of the present invention 1-x Eu x Mo 1-x Nb x Scanning electron microscope (SEM) surface morphology of O4 (x = 0.1, 0.3, 0.5) (a: x = 0.1; b: x = 0.3; c: x = 0.5).

[0031] Figure 5 The low-dielectric Mo-based microwave dielectric ceramic Ca prepared in Examples 6-10 of the present invention 0.4 Eu 0.6 Mo 0.4 Nb 0.6Scanning electron microscope (SEM) surface morphology of O4 (a: 1350℃; b: 1375℃; c: 1400℃; d: 1425℃; e: 1450℃).

[0032] Figure 6 Simulation diagram of substrate integrated resonant antenna (a: simulation structure design diagram; b: return loss; c: gain and efficiency diagram). DETAILED DESCRIPTION

[0033] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0034] Example 1

[0035] Reference Figure 1 , low-dielectric molybdenum-based microwave dielectric ceramics are prepared according to the following preparation method:

[0036] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with purity greater than 99.9% were prepared by 1-x Eu x Mo 1-x Nb x The composition of O4 (x=0.1) was weighed and prepared, wherein the molar ratio of Nb2O5, Eu2O3, CaCO3 and MoO3 was 1:1:18:18;

[0037] (2) the raw materials of step (1) were subjected to a first wet ball milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by drying, mixing after drying, and then subjected to a second wet milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by a second drying, and then pre-calcined in an atmosphere at 1000° C. for 4 hours;

[0038] (3) Adding a polyvinyl alcohol solution with a mass concentration of 5% as a binder to the powder obtained in step (2), the amount of polyvinyl alcohol added accounts for 3% of the total mass of the powder. After granulation, the powder is pressed into shape and finally sintered in an atmosphere at 1250°C for 6 hours to obtain a molybdenum-based microwave dielectric ceramic.

[0039] Example 2

[0040] Reference Figure 1 , low-dielectric molybdenum-based microwave dielectric ceramics are prepared according to the following preparation method:

[0041] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with purity greater than 99.9% were prepared by 1-x Eux Mo 1-x Nb x The composition of O4 (x=0.2) was weighed and prepared, wherein the molar ratio of Nb2O5, Eu2O3, CaCO3 and MoO3 was 1:1:8:8;

[0042] (2) the raw materials of step (1) were subjected to a first wet ball milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by drying, mixing after drying, and then subjected to a second wet milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by a second drying, and then pre-calcined in an atmosphere at 1000° C. for 4 hours;

[0043] (3) Adding a polyvinyl alcohol solution with a mass concentration of 5% as a binder to the powder obtained in step (2), the amount of polyvinyl alcohol added accounts for 3% of the total mass of the powder. After granulation, the powder is pressed into shape and finally sintered in an atmosphere at 1325°C for 6 hours to obtain a molybdenum-based microwave dielectric ceramic.

[0044] Example 3

[0045] Reference Figure 1 , low-dielectric molybdenum-based microwave dielectric ceramics are prepared according to the following preparation method:

[0046] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with purity greater than 99.9% were prepared by 1-x Eu x Mo 1-x Nb x The composition of O4 (x=0.3) was weighed and prepared, wherein the molar ratio of Nb2O5, Eu2O3, CaCO3 and MoO3 was 3:3:14:14;

[0047] (2) the raw materials of step (1) were subjected to a first wet ball milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by drying, mixing after drying, and then subjected to a second wet milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by a second drying, and then pre-calcined in an atmosphere at 1000° C. for 4 hours;

[0048] (3) Adding a polyvinyl alcohol solution with a mass concentration of 5% as a binder to the powder obtained in step (2), the amount of polyvinyl alcohol added accounts for 3% of the total mass of the powder. After granulation, the powder is pressed into shape and finally sintered in an atmosphere at 1325°C for 6 hours to obtain a molybdenum-based microwave dielectric ceramic.

[0049] Example 4

[0050] Reference Figure 1 , low-dielectric molybdenum-based microwave dielectric ceramics are prepared according to the following preparation method:

[0051] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with purity greater than 99.9% were prepared by 1-x Eu x Mo 1-x Nb x The composition of O4 (x=0.4) was weighed and prepared, wherein the molar ratio of Nb2O5, Eu2O3, CaCO3 and MoO3 was 1:1:3:3;

[0052] (2) the raw materials of step (1) were subjected to a first wet ball milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by drying, mixing after drying, and then subjected to a second wet milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by a second drying, and then pre-calcined in an atmosphere at 1000° C. for 4 hours;

[0053] (3) Adding a polyvinyl alcohol solution with a mass concentration of 5% as a binder to the powder obtained in step (2), the amount of polyvinyl alcohol added accounts for 3% of the total mass of the powder. After granulation, the powder is pressed into shape and finally sintered in an atmosphere at 1325°C for 6 hours to obtain a molybdenum-based microwave dielectric ceramic.

[0054] Example 5

[0055] Reference Figure 1 , low-dielectric molybdenum-based microwave dielectric ceramics are prepared according to the following preparation method:

[0056] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with purity greater than 99.9% were prepared by 1-x Eu x Mo 1-x Nb x The composition of O4 (x=0.5) was weighed and prepared, wherein the molar ratio of Nb2O5, Eu2O3, CaCO3 and MoO3 was 1:1:2:2;

[0057] (2) the raw materials of step (1) were subjected to a first wet ball milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by drying, mixing after drying, and then subjected to a second wet milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by a second drying, and then pre-calcined in an atmosphere at 1000° C. for 4 hours;

[0058] (3) Adding a polyvinyl alcohol solution with a mass concentration of 5% as a binder to the powder obtained in step (2), wherein the amount of polyvinyl alcohol added accounts for 3% of the total mass of the powder. After granulation, the powder is pressed into shape and finally sintered in an atmosphere at 1375°C for 6 hours to obtain a molybdenum-based microwave dielectric ceramic.

[0059] Example 6

[0060] Reference Figure 1 , low-dielectric molybdenum-based microwave dielectric ceramics are prepared according to the following preparation method:

[0061] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with purity greater than 99.9% were prepared by 1-x Eu x Mo 1-x Nb x The composition of O4 (x=0.6) was weighed and prepared, wherein the molar ratio of Nb2O5, Eu2O3, CaCO3 and MoO3 was 3:3:4:4;

[0062] (2) the raw materials of step (1) were subjected to a first wet ball milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by drying, mixing after drying, and then subjected to a second wet milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by a second drying, and then pre-calcined in an atmosphere at 1000° C. for 4 hours;

[0063] (3) Adding a polyvinyl alcohol solution with a mass concentration of 5% as a binder to the powder obtained in step (2), the amount of polyvinyl alcohol added accounts for 3% of the total mass of the powder. After granulation, the powder is pressed into shape and finally sintered in an atmosphere at 1350°C for 6 hours to obtain a molybdenum-based microwave dielectric ceramic.

[0064] Example 7

[0065] Referring to Example 6, the sintering temperature in step (3) was set to 1375°C, and the other parameters were the same as those in Example 6 to prepare Ca 1-x Eu x Mo 1-x Nb x O4 (x=0.6) molybdenum-based microwave dielectric ceramics.

[0066] Example 8

[0067] Referring to Example 6, the sintering temperature in step (3) was set to 1400°C, and the other parameters were the same as those in Example 6 to prepare Ca 1-x Eu x Mo 1-x Nb x O4 (x=0.6) molybdenum-based microwave dielectric ceramics.

[0068] Example 9

[0069] Referring to Example 6, the sintering temperature in step (3) was set to 1425°C, and the other parameters were the same as those in Example 6 to prepare Ca 1-x Eu x Mo 1-x Nb x O4 (x=0.6) molybdenum-based microwave dielectric ceramics.

[0070] Example 10

[0071] Referring to Example 6, the sintering temperature in step (3) was set to 1450°C, and the other parameters were the same as those in Example 6 to prepare Ca 1-x Eu x Mo 1-x Nb x O4 (x=0.6) molybdenum-based microwave dielectric ceramics.

[0072] Example 11

[0073] like Figure 5 As shown in (a), the microwave dielectric ceramic Ca prepared in Example 8 1-x Eu x Mo 1-x Nb x O4 (x = 0.6) is designed as a substrate integrated resonant antenna with a working center frequency of 4.23 GHz for satellite communication. The substrate integrated resonant antenna includes: a dielectric resonant antenna, a substrate, a rectangular slot microstrip coupling slot, and a metal feed line. The dielectric resonant antenna is made of the Ca obtained in Example 8. 0.4 Eu 0.6 Mo 0.4 Nb 0.6 Made of O4 microwave dielectric ceramic material, the dielectric resonant antenna has a center frequency of 4.23GHz and is a cylindrical structure with a height of 8.07mm and a diameter of 16.98mm. A substrate is tightly fixed below the dielectric resonant antenna, and the dielectric resonant antenna is located directly above the substrate. The substrate is a square Arlon CLTE-XT with a dielectric constant of 2.94, a loss tangent of 0.0012, a length of 50mm, a width of 50mm, and a thickness of 0.76mm. A rectangular slot measuring 7.0mm long and 2.3mm wide is provided in the center of the substrate. The rectangular slot serves as a microstrip coupling slot, isolating the feed network at the bottom of the substrate to avoid coupling losses. The upper surface of the substrate is coated with a layer of copper as a metal ground, and the lower surface of the substrate is provided with a metal feed line with a length of 29.4mm and a width of 1.91mm. One end of the metal feed line is flush with the edge of the substrate, and the other extends into the middle of the substrate. The metal feed line acts as a conductive wire. The specific size parameters are shown in Table 1 below, where r0 and h are the radius and height of the dielectric resonant antenna, respectively, a is the side length of the dielectric substrate, h0 is the thickness of the dielectric substrate, and the length of the rectangular gap microstrip coupling slot is l s , with a width of w s , w f is the width of the metal feeder, l x The distance that the metal feed line extends beyond the center of the dielectric substrate.

[0074] Table 1Ca0.4 Eu 0.6 Mo 0.4 Nb 0.6 O4 ceramic DRA design size parameters

[0075] parameter a <![CDATA[h0]]> <![CDATA[r0]]> h <![CDATA[l s ]]> <![CDATA[w s ]]> <![CDATA[w f ]]> <![CDATA[l x ]]> size 50 0.76 8.49 8.07 7.000 2.4 1.91 4.400

[0076] Data testing and analysis:

[0077] Furthermore, the present invention uses the cylindrical dielectric resonator method to evaluate the performance of microwave dielectric ceramics prepared in Examples 1-10. Specifically, the Hakki-Coleman method is used to measure the dielectric constant ε of solid materials. r It can only be measured at a resonant frequency corresponding to the TE011 mode. In order to avoid the problem of conduction and radiation losses, the Q value of microwave dielectric ceramic samples can be measured by the resonant cavity method, where the sample is placed in a low-loss spacer cavity. The resonant frequency temperature coefficient (τ f ) can be used to measure the stability of devices made of materials under different working environments. It represents the "drift" of the resonant frequency as the temperature changes. The relationship between resonant frequency and temperature is as follows:

[0078]

[0079] Where f0 is the initial resonant frequency, Δf is the change in resonant frequency, and ΔT is the temperature change. The properties of the prepared microwave dielectric ceramics are shown in Table 2:

[0080] Table 2 Microwave dielectric properties of a series of molybdenum-based microwave dielectric ceramics prepared in Examples 1 to 10

[0081]

[0082]

[0083] As can be seen from Table 2, the prepared low-dielectric Mo-based microwave dielectric ceramics with adjustable wide-range microwave dielectric properties have a high quality factor (Q×f) value (21950~82930GHz) and low dielectric loss; its dielectric constant reaches 11.4~15.6, and the resonant frequency temperature coefficient τ f The temperature stability is good between (-47.7~+6.0ppm / ℃). 1-x Eu x Mo 1-x Nb x The phases of O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) microwave dielectric ceramics are all single phase, not easy to deliquesce, with stable crystal structure and suitable for mass production. 1-x Eux Mo 1-x Nb x O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) microwave dielectric ceramic materials ensure high quality factor and low dielectric constant without adding modified materials, while completing the serialization of low-dielectric Mo-based microwave dielectric ceramics and improving the τ of the originally reported Mo-based microwave dielectric ceramics. f At the same time, the Ca prepared at a sintering temperature of 1350℃ 0.4 Eu 0.6 Mo 0.4 Nb 0.6 The microwave dielectric properties of O4 microwave dielectric ceramics are ε r =14.5, Q×f=84200GHz, τ f =4.0ppm / ℃.

[0084] Figure 2 The low-K Mo-based microwave dielectric ceramic Ca with adjustable wide-range microwave dielectric properties prepared in Examples 1-6 1- x Eu x Mo 1-x Nb x X-ray diffraction (XRD) spectra of O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6). It can be seen from the figure that when 0.1≤x≤0.6, Ca 1-x Eu x Mo 1-x Nb x The physical phase of O4 microwave dielectric ceramic is pure tetragonal scheelite structure, which is consistent with the PDF card PDF#01-085-0546 of CaMoO4, and no impurity phase is found. This shows that the preparation method of the present invention can ensure that the microwave dielectric ceramic material has a high quality factor and low dielectric constant without adding any modifying materials, and is beneficial to the quality factor (Q×f) value and dielectric constant (ε r ), resonant frequency temperature coefficient (τ f ) for precise control.

[0085] Figure 3 The low-K Mo-based microwave dielectric ceramic Ca with adjustable wide-range microwave dielectric properties prepared in Examples 1-6 1- x Eu x Mo 1-x Nb x XRD structure refinement patterns of O4 (x=0.1、0.2、0.3、0.4、0.5、0.6). Firstly, it can be seen from the figure that the lower reliability factor (R p 、Rwp and χ 2 <10) indicates that the refinement results are reliable. It further shows that the prepared ceramic is a single-phase ceramic material. In addition, from the specific bond length data obtained from the refinement, it is found that the AO bond is gradually stretched and the BO bond is gradually compressed. For molybdenum-based scheelite CaMoO4, the introduction of Nb with a larger ionic radius at the B position 5+ Replace Mo 6+ , while using a smaller cation Eu at the A position 3+ Replace Ca 2+ , according to the conventional average bond length of AO bond should be shortened, and the bond length of BO bond should be stretched. However, X-ray diffraction structure analysis, that is, XRD result refinement shows ( Figure 3 ), the AO bond gradually stretches and the BO bond gradually compresses. This unexpected effect is the reason why it has low dielectric constant, low loss and near-zero resonant frequency temperature coefficient. Through PVL complex chemical bond calculations, it was found that since the AO bond plays a dominant role in microwave dielectric polarization, the A-site cation caused by the stretching of the AO bond produces a rattling effect, which will lead to the τ f Value and ε r At the same time, the BO bond plays a dominant role in the total lattice energy and bond energy, so the compression of the BO bond can lead to an increase in the total lattice energy and bond energy, resulting in a decrease in dielectric loss and an increase in Q×f. Through the synergistic effect of the AO bond and the BO bond, the Ca 1-x Eu x Mo 1-x Nb x The microwave dielectric properties of O4 (0.1≤x≤0.6) give it low dielectric constant, low loss and near-zero resonant frequency temperature coefficient.

[0086] from Figure 4 It can be seen that the prepared ceramics have uniform grain size, dense structure and no obvious pores and second phases, indicating that relatively dense Ca2O3 can be obtained by this preparation method. 1-x Eu x Mo 1-x Nb x O4 microwave dielectric ceramic material.

[0087] from Figure 5 It can be seen that at 1350℃, there are obvious impurities and a large number of pores. As the sintering temperature rises, the pores gradually decrease. At 1400℃, the grain size is uniform, the structure is dense, and there are no obvious pores and second phases. As the temperature continues to rise, a small amount of pores and cracks begin to appear in the ceramic. At 1425℃, the grains grow abnormally and are slightly over-burned. This shows that Ca 1-x Eu x Mo 1-x Nbx The sintering temperature of O4 (x = 0.6) ceramics has a significant impact on their micromorphology, with the optimal sintering temperature being 1400°C. This indicates that the coordinated control of "process temperature + component doping" has broadened the adjustment range of molybdenum-based microwave dielectric ceramic materials.

[0088] from Figure 6 It can be seen that the designed substrate integrated resonant antenna has a gain of 6.1dBi at the center resonant frequency (3.69GHz). 11 The radiation efficiency in the <-10dB region reaches over 90%, indicating that the preparation method of the low-K Mo-based microwave dielectric ceramic is feasible and effective, meeting the operational requirements of 5G communication technology.

[0089] The above disclosure is merely a preferred embodiment of the present invention's low-K, molybdenum-based microwave dielectric ceramics with adjustable wide-range microwave dielectric properties and their preparation methods. This is not intended to limit the scope of the present invention. Persons skilled in the art will appreciate that equivalent variations made by implementing all or part of the above-described embodiments in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A low-K Mo-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties, characterized in that: The chemical formula of the molybdenum-based microwave dielectric ceramic is: Ca 1-x Eu x Mo 1-x Nb x O4 (0.1≤x≤0.6), its dielectric constant range is 11.4~15.8, its quality factor range is 21950~82930GHz, τ f The chemical formula of the molybdenum-based microwave dielectric ceramic is -47.7ppm / ℃~+6.0ppm / ℃: 1-x Eu x Mo 1-x Nb x O4(0.1≤x≤0.6).

2. The low-K Mo-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties according to claim 1, characterized in that: The chemical formula of the molybdenum-based microwave dielectric ceramic is: Ca 0.4 Eu 0.6 Mo 0.4 Nb 0.6 O4, whose dielectric constant ranges from 15.6, quality factor ranges from 82930GHz, τ f +4.0ppm / ℃.

3. The low-K Mo-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties according to claim 1, characterized in that: The preparation method of the molybdenum-based microwave dielectric ceramic comprises the following steps: (1) Weighing Nb2O5, Eu2O3, CaCO3 and MoO3 powders to obtain raw powders; (2) the raw powder of step (1) was subjected to a first wet ball milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by drying, mixing after drying, and then subjected to a second wet milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by a second drying, and then pre-calcined in an atmosphere at 1000° C. for 4 hours; (3) Adding a binder to the pre-sintered powder in step (2) to granulate, and pressing into shape, and finally sintering at 1250-1450° C. in an atmosphere for 6 hours to obtain a molybdenum-based microwave dielectric ceramic.

4. The low-K Mo-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties according to claim 2, characterized in that: The preparation method of the molybdenum-based microwave dielectric ceramic comprises the following steps: (1) Weighing Nb2O5, Eu2O3, CaCO3 and MoO3 powders to obtain raw powders; (2) the raw powder of step (1) was subjected to a first wet ball milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by drying, mixing after drying, and then subjected to a second wet milling treatment using anhydrous ethanol as a ball milling medium for 6 hours, followed by a second drying, and then pre-calcined in an atmosphere at 1000° C. for 4 hours; (3) Adding a binder to the pre-sintered powder in step (2) to granulate, and pressing into shape, and finally sintering at 1350-1450° C. in an atmosphere for 6 hours to obtain a molybdenum-based microwave dielectric ceramic.

5. The low-K Mo-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties according to claim 4, characterized in that: In the step (2), the wet milling treatment time is 6 hours, and the ball milling medium is anhydrous ethanol.

6. The low-K Mo-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties according to claim 5, characterized in that: In the step (3), the binder is a polyvinyl alcohol solution with a mass concentration of 5%, and the added mass of the binder accounts for 3% of the total mass of the original powder.

7. The low-K Mo-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties according to claim 6, characterized in that: In the step (3), the sintering temperature is 1350°C.

8. The low-K Mo-based microwave dielectric ceramic with adjustable wide-range microwave dielectric properties according to claim 7, characterized in that: In the step (3), the sintering temperature is 1400°C.

9. A substrate-integrated resonant antenna prepared using the molybdenum-based microwave dielectric ceramic according to claim 8, characterized in that: The substrate integrated resonant antenna comprises: a dielectric resonant antenna, a substrate, a rectangular slot microstrip coupling slot, and a metal feed line. 0.4 Eu 0.6 Mo 0.4 Nb 0.6 Made of O4 microwave dielectric ceramic material, a substrate is tightly secured beneath the dielectric resonant antenna, with the antenna positioned directly above it. A rectangular slot is located in the center of the substrate, serving as a microstrip coupling slot that isolates the feed network at the bottom of the substrate, preventing coupling losses. A layer of copper is coated on the upper surface of the substrate as a metal ground, while a metal feed line is located on the lower surface, serving as a conductive conductor.

10. The substrate integrated resonant antenna according to claim 9, characterized in that: The center frequency of the dielectric resonant antenna is 4.23 GHz, and it has a cylindrical structure with a height of 8.07 mm and a diameter of 16.98 mm. The substrate is a square Arlon CLTE-XT with a dielectric constant of 2.94, a loss tangent of 0.0012, a length of 50 mm, a width of 50 mm, and a thickness of 0.76 mm. The rectangular slot has a length of 7.0 mm and a width of 2.3 mm. The metal feed line is 29.4 mm long and 1.91 mm wide. One end of the metal feed line is flush with the edge of the substrate, and the other end extends into the middle of the substrate.

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