Microwave dielectric property wide-range adjustment method of europium niobate-based microwave dielectric ceramic and preparation method of europium niobate-based microwave dielectric ceramic

Abstract

The invention relates to the technical field of ceramic materials, in particular to microwave dielectric property wide-range adjustment of europium niobate-based microwave dielectric ceramics and a preparation method of the europium niobate-based microwave dielectric ceramics, according to the method, three performance parameters of EuNbO4 are regulated and controlled through the cooperation of A / B site regulation, ratling effect and compact effect, the chemical formula of the europium niobate-based microwave dielectric ceramics is Eu1-xCaxNb1-xMoxO4 (0 < = x < = 0.38), Nb2O5, Eu2O3, CaCO3 and MoO3 are used as raw materials, and the europium niobate-based microwave dielectric ceramics are prepared through a one-step method. The europium niobate-based microwave dielectric ceramic is prepared by the processes of ball milling, sintering and the like, the prepared europium niobate-based microwave dielectric ceramic realizes wide-range adjustment of dielectric constant, quality factor and resonant frequency temperature coefficient, and the europium niobate-based microwave dielectric ceramic has the advantages of improving selectivity of working frequency of a device, simplifying heat dissipation design and the like when being made into a substrate integrated resonant antenna.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and in particular to the wide-range tuning of microwave dielectric properties of europium niobate-based microwave dielectric ceramics and their preparation methods. Background Technology

[0002] Microwave dielectric ceramics (MWDC) refer to ceramics used as dielectric materials in microwave frequency band (300MHz-300 GHz) circuits, performing one or more functions such as microwave waveguides, shielding, and resonance. They are key fundamental materials in modern communication technologies such as microwave communication, high-speed and high-frequency circuit boards, satellite positioning and navigation systems, and radar detection, and are widely used as resonators, filters, dielectric substrates, and dielectric waveguide circuits. The rapid development of modern mobile communication is driving the miniaturization, lightweighting, multi-functionality, and low cost of various microwave mobile communication terminal devices. With the deepening application of 5G technology, microwave communication technology is extending 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 1) To improve the transmission rate of electrical signals (a low dielectric constant can reduce the interaction coupling of electromagnetic signals and increase the propagation speed of electromagnetic waves); 2) Quality factor (low dielectric loss, usually requiring Q×f≥30000GHz) to improve the selectivity of device operating frequency and reduce the energy conversion consumption of the device; 3) Near-zero temperature coefficient of resonant frequency (τ). f To ensure signal stability during resonance and transmission, low dielectric and high quality factor microwave dielectric ceramic materials (dielectric constant ε) are used. r <20) has been explored and studied by researchers at home and abroad in recent years.

[0003] A series of recent dielectric constants ε r Microwave dielectric ceramic systems of monoclinic yttrium niobium ReNbO4 with a gradation of <20 have been reported, such as CeNbO4(ε r =11.9, Q×f=42,500GHz, τ f =-40.0ppm / ℃), NdNbO4(ε r =19.6, Q×f=33,000GHz, τ f =-24.0ppm / ℃), SmNbO4(ε r =18.8, Q×f=56,300GHz,τ f =-40.0ppm / ℃), DyNbO4(ε r =17.8, Q×f=38,500GHz, τ f =-66.0ppm / ℃), ErNbO4(ε r=16.6,Q×f=49,300GHz,τ f =-64.0ppm / ℃), LuNbO4(ε r =17.4, Q×f=56,600GHz, τ f =-64.0ppm / ℃), etc. This ceramic system possesses a low dielectric constant and a high quality factor, and its crystal structure is simple and flexible, but its τ... f The values ​​are all relatively large negative values. It is worth noting that Wu Haitao et al. reported EuNbO4(ε)... r =19.1,Q×f=15,014GHz,τ f =-16.4ppm / ℃) but has a τ value closer to zero. f It has a high value, but the material has a large loss rate.

[0004] Currently, some challenges remain in the research and development of EuNbO4 microwave dielectric ceramics. For example, research and development approaches for controlling EuNbO4 are all based on a single mechanism to regulate material properties, making it impossible to control Q×f, ε r , f To carry out overall planning and control. For example, Zhou Di et al. used V to control the growth of LaNbO4 ceramics. 5+ Nb replaces B 5+ The ions effectively reduced the sintering temperature, and the optimal microwave dielectric properties were: Q×f=75,940GHz, r=17.8, f=-36.8ppm / ℃. 5+ The incorporation of [a substance] lowered the sintering temperature and increased the Q×f value, but the performance of [a substance] in the ceramic deteriorated. A-site substitution has also been studied; researchers have investigated this by substituting Bi[a substance] at the A-site. 3+ By using ions to modulate the microwave dielectric properties of SmNbO4 ceramics, they found that decreasing the sintering temperature led to smaller grain size and a slightly lower Q×f value, ultimately resulting in (Sm 0.875 Bi 0.125 NbO4 ceramics have microwave dielectric properties of ε. r =21.9, Q×f=38,300GHz, and two different near-zero τ were obtained. f The values ​​are -9.0 and -6.6 ppm / ℃. While the aforementioned studies may optimize one parameter, they often worsen another, making it difficult to simultaneously control all three performance parameters.

[0005] The traditional approach is to adjust the dielectric properties of EuNbO4 microwave dielectric ceramics through alternative doping, by introducing other ions at the B site. When the radius of the introduced other ions is larger than that of Nb... 5+ When the BO bond is elongated, and other ions with radii smaller than Nb are introduced, the BO bond will be stretched. 5+At this time, its BO bond will shorten, or other ions will be introduced at the A site. When the radius of the introduced other ions is larger than that of Eu... 3+ When the AO bond is elongated, and other ions with radii smaller than Eu are introduced, the AO bond will elongate. 3+ When the AO bond length is adjusted, the temperature coefficient of the resonant frequency (τ) is shortened, meaning that the temperature coefficient of the resonant frequency can be adjusted by regulating the bond lengths of the AO and BO bonds. f ) and Q×f value. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing europium niobate-based microwave dielectric ceramics with controlled properties. The aim is to develop single-phase europium niobate-based microwave dielectric ceramics with low dielectric constant, low loss and near-zero resonant frequency temperature coefficient, and to provide theoretical and experimental support for the control of microwave dielectric properties of this ceramic system. The invention also establishes universal rules to provide strategies for controlling the microwave dielectric properties of europium niobate-based ceramics for subsequent researchers or inventors.

[0007] To achieve the above objectives, firstly, this patent discloses a method for wide-range adjustment of the microwave dielectric properties of europium niobate-based microwave dielectric ceramics. This method achieves the regulation of the three major performance parameters of EuNbO4 through the synergistic effect of "A / B site regulation + rattling effect + compressed effect". The europium niobate-based microwave dielectric ceramic has a monoclinic structure, with Ca ions replacing Eu ions at the A site and Mo ions replacing Nb ions at the B site. The chemical formula of the europium niobate-based microwave dielectric ceramic is: Eu 1-x Ca x Nb 1- x Mo x O4(0.1≤x≤0.32).

[0008] Secondly, the present invention also provides a method for preparing europium niobate-based microwave dielectric ceramics, comprising the following steps:

[0009] (1) According to Eu 1-x Ca x Nb 1-x Mo x Weigh Nb2O5, Eu2O3, CaCO3 and MoO3 raw material powders according to the atomic ratio of O4 (0.1≤x≤0.32);

[0010] (2) The raw material powder is stirred and mixed, and then wet milled for the first time under the condition of adding ball milling media. Then it is dried, and then mixed again. A second wet milling is performed under the condition of ball milling media, and then a second drying is performed to obtain dried powder. Then it is pre-calcined in an atmospheric atmosphere at 1000°C for 4 hours to obtain pre-calcined powder.

[0011] (3) Add a binder to the pre-fired powder to granulate, press it into shape, and finally sinter it in an atmospheric atmosphere at 1300-1400℃ for 6 hours to obtain europium niobate-based microwave dielectric ceramic.

[0012] Preferably, in step (1), the time for the first wet milling treatment and the second wet milling treatment is 6 hours, and the ball milling media used in both treatments is anhydrous ethanol.

[0013] Preferably, in step (3), the binder is a polyvinyl alcohol solution with a mass concentration of 5%, and the amount of binder added is 3% of the total mass of the raw material powder.

[0014] Preferably, in step (3), the sintering temperatures are 1400℃, 1375℃, and 1350℃.

[0015] This series of europium niobate-based microwave dielectric ceramics has a high quality factor (Q×f) value (64210~79950GHz) and low dielectric loss; its dielectric constant (ε) r The temperature coefficient of resonant frequency (τ) reaches 18.2–16.2. f The ppm value is between -32.3 ppm / ℃ and +8.0 ppm / ℃, indicating good temperature stability.

[0016] Thirdly, this invention also provides an application of europium niobate-based microwave dielectric ceramics, specifically a substrate integrated resonant antenna. The substrate integrated resonant antenna includes: a dielectric resonant antenna, a substrate, a rectangular slot microstrip coupling groove, and a metal feed line. The dielectric resonant antenna is made of Eu... 1-x Ca x Nb 1-x Mo x The antenna is made of O4 (x = 0.32) microwave dielectric ceramic material. A substrate is tightly fixed below the dielectric resonant antenna, which is positioned directly above the substrate. A rectangular slot is provided in the center of the substrate, which serves as a microstrip coupling slot to isolate the feed network at the bottom of the substrate, avoiding coupling losses. The upper surface of the substrate is coated with a layer of copper as a metal ground, and a metal feed line is provided on the lower surface of the substrate, which acts as a conductor.

[0017] Preferably, the center frequency of the dielectric resonant antenna is 3.67 GHz, and it is a cylindrical structure with a height of 8.06 mm and a diameter of 16.4 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 7.01 mm and a width of 2.28 mm. The metal feed line has a length of 29.8 mm and a width of 1.91 mm, with one end flush with the edge of the substrate and the other end extending into the middle of the substrate.

[0018] Beneficial effects

[0019] (1) The “A / B site regulation + rattling effect + compressed effect” method involved in this invention achieves coordinated regulation of the three major performance parameters of europium niobate-based ceramics, and can accurately predict the increase in quality factor (Q×f) value and increase τ f The value is made to approach zero, and ε is reduced. r The value provides a good strategy for regulating europium niobate-based ceramics.

[0020] (2) This series of europium niobate-based microwave dielectric ceramics has a high quality factor (Q×f) value (64210~79950GHz) and low dielectric loss; its dielectric constant (ε r The temperature coefficient of resonant frequency (τ) reaches 18.2–16.2. f The ppm value is between -32.3 ppm / ℃ and +8.0 ppm / ℃, indicating good temperature stability.

[0021] (3) The preparation method of this invention does not require the addition of modifying materials, and the obtained europium niobate-based microwave dielectric ceramic Eu 1- x Ca x Nb 1-x Mo x O4 (0.1≤x≤0.32) is a single pure phase. Due to its single composition, it ensures a high quality factor and low dielectric constant, which is beneficial for the quality factor (Q×f) and dielectric constant (ε) of microwave dielectric ceramic materials. r ) and temperature coefficient of resonant frequency (τ) f (Precise regulation)

[0022] (4) The substrate integrated resonant antenna designed in this invention utilizes Eu 1-x Ca x Nb 1-x Mo x O4 (x = 0.32) microwave dielectric ceramics have a good quality factor (Q×f) and a low dielectric constant (ε). rWith a near-zero temperature coefficient of resonant frequency, the designed substrate integrated resonant antenna has a gain of 6.2 dBi at the center resonant frequency (3.69 GHz). 11 The radiation efficiency in the <-10dB region reaches over 90%, meeting the operational requirements of 5G communication technology. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic flowchart of the preparation method of europium niobate-based microwave dielectric ceramic materials prepared in Examples 1-4 of the present invention.

[0025] Figure 2 Europium niobate-based microwave dielectric ceramics Eu prepared in Examples 1-4 of this invention 1-x Ca x Nb 1-x Mo x X-ray diffraction (XRD) pattern of O4.

[0026] Figure 3 Europium niobate-based microwave dielectric ceramics Eu prepared in Examples 1-4 of this invention 1-x Ca x Nb 1-x Mo x Scanning electron microscope (SEM) image of the surface morphology of O4.

[0027] Figure 4 The simulation diagrams for the substrate integrated resonant antenna are shown below (a: simulation structure design diagram; b: return loss; c: gain and efficiency diagrams). Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] Example 1

[0030] Reference Figure 1 A method for preparing a europium niobate-based microwave dielectric ceramic material includes the following steps:

[0031] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with a purity >99.9% were mixed according to Eu... 1-x Ca x Nb 1-x Mo x Weigh and mix the ingredients according to the atomic ratio of O4 (x=0.1) to obtain raw material powder;

[0032] (2) Stir and mix the raw material powder obtained in step (1), add anhydrous ethanol as the ball milling medium and perform a first wet milling for 6 hours, then dry it, mix it again after drying, and then perform a second wet milling for 6 hours under the anhydrous ethanol ball milling medium, and then dry it a second time. After drying, pre-calcine it in an atmospheric atmosphere at 1000℃ for 4 hours to obtain pre-calcineed powder.

[0033] (3) After adding a binder to the pre-calcined powder obtained in step (2) and granulating it, it is pressed into shape and finally sintered in an atmospheric atmosphere at 1400°C for 6 hours. The binder is a polyvinyl alcohol solution with a mass concentration of 5%. The amount of binder added is 3% of the total mass of the raw material powder.

[0034] Example 2

[0035] A method for preparing a europium niobate-based microwave dielectric ceramic material includes the following steps:

[0036] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with a purity >99.9% were mixed according to Eu... 1-x Ca x Nb 1-x Mo x Weigh and mix the ingredients according to the atomic ratio of O4 (x=0.2) to obtain raw material powder;

[0037] (2) Stir and mix the raw material powder obtained in step (1), add anhydrous ethanol as the ball milling medium and perform a first wet milling for 6 hours, then dry it, mix it again after drying, and then perform a second wet milling for 6 hours under the anhydrous ethanol ball milling medium, and then dry it a second time. After drying, pre-calcine it in an atmospheric atmosphere at 1000℃ for 4 hours to obtain pre-calcineed powder.

[0038] (3) After adding a binder to the pre-calcined powder obtained in step (2) and granulating it, it is pressed into shape and finally sintered at 1375°C in an atmospheric atmosphere for 6 hours. The binder is a 5% polyvinyl alcohol solution by mass, and the amount of binder added is 3% of the total mass of the raw material powder by mass.

[0039] Example 3

[0040] A method for preparing a europium niobate-based microwave dielectric ceramic material includes the following steps:

[0041] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with a purity >99.9% were mixed according to Eu... 1-x Ca x Nb 1-x Mo x Weigh and mix the ingredients according to the atomic ratio of O4 (x=0.3) to obtain raw material powder;

[0042] (2) Stir and mix the raw material powder obtained in step (1), add anhydrous ethanol as the ball milling medium and perform a first wet milling for 6 hours, then dry it, mix it again after drying, and then perform a second wet milling for 6 hours under the anhydrous ethanol ball milling medium, and then dry it a second time. After drying, pre-calcine it in an atmospheric atmosphere at 1000℃ for 4 hours to obtain pre-calcineed powder.

[0043] (3) After adding a binder to the pre-calcined powder obtained in step (2) and granulating it, it is pressed into shape and finally sintered in an atmospheric atmosphere at 1350°C for 6 hours. The binder is a polyvinyl alcohol solution with a mass concentration of 5%. The amount of binder added is 3% of the total mass of the raw material powder.

[0044] Example 4

[0045] A method for preparing a europium niobate-based microwave dielectric ceramic material includes the following steps:

[0046] (1) The original powders of Nb2O5, Eu2O3, CaCO3 and MoO3 with a purity >99.9% were mixed according to Eu... 1-x Ca x Nb 1-x Mo x Weigh and mix the ingredients according to the atomic ratio of O4 (x = 0.32) to obtain raw material powder;

[0047] (2) Stir and mix the raw material powder obtained in step (1), add anhydrous ethanol as the ball milling medium and perform a first wet milling for 6 hours, then dry it, mix it again after drying, and then perform a second wet milling for 6 hours under the anhydrous ethanol ball milling medium, and then dry it a second time. After drying, pre-calcine it in an atmospheric atmosphere at 1000℃ for 4 hours to obtain pre-calcineed powder.

[0048] (3) After adding a binder to the pre-calcined powder obtained in step (2) and granulating it, it is pressed into shape and finally sintered in an atmospheric atmosphere at 1350°C for 6 hours. The binder is a polyvinyl alcohol solution with a mass concentration of 5%. The amount of binder added is 3% of the total mass of the raw material powder.

[0049] Example 5

[0050] A method utilizing Eu 1-x Cax Nb 1-x Mo x The application of O4 (x = 0.32) microwave dielectric ceramic: Using the microwave dielectric ceramic prepared in Example 4, it is applied to fabricate a substrate integrated resonant antenna. This substrate integrated resonant antenna includes: a dielectric resonant antenna, a substrate, a rectangular slotted microstrip coupling groove, and a metal feed line. The dielectric resonant antenna is made of Eu... 1-x Ca x Nb 1-x Mo x The dielectric resonant antenna is made of O4 (x = 0.32) microwave dielectric ceramic material. A substrate is tightly fixed below the dielectric resonant antenna, which is positioned directly above the substrate. A rectangular slot is provided in the center of the substrate, which serves as a microstrip coupling slot to isolate the feed network at the bottom of the substrate, avoiding coupling losses. A copper layer is coated on the upper surface of the substrate as a metal ground, and a metal feed line is provided on the lower surface of the substrate, which acts as a conductor. The center frequency of the dielectric resonant antenna is 3.67 GHz, and it is a cylindrical structure with a height of 8.06 mm and a diameter of 16.4 mm. The substrate is a square Arlon CLTE-XT material 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 7.01 mm and a width of 2.28 mm. The metal feed line has a length of 29.8 mm and a width of 1.91 mm, with one end flush with the edge of the substrate and the other end extending into the middle of the substrate.

[0051] Figure 2 The series of europium niobate-based microwave dielectric ceramics Eu prepared in Examples 1-4 1-x Ca x Nb 1-x Mo x X-ray diffraction (XRD) pattern of O4 (0.1≤x≤0.32). The figure shows that when 0.1≤x≤0.32, Eu... 1-x Ca x Nb 1-x Mo x The phase composition of the O4 microwave dielectric ceramic is a pure monoclinic structure, consistent with the PDF card PDF#00-022-1099 for EuNbO4, and no impurity phases were found. This indicates that the preparation method of the aforementioned series of europium niobate-based microwave dielectric ceramics is feasible and effective, simple, and has low production costs.

[0052] Figure 3 The series of europium niobate-based microwave dielectric ceramics Eu prepared in Examples 1-4 1-x Ca x Nb 1-x Mo xSEM images of Europium niobate (0.1 ≤ x ≤ 0.32) are shown. The images reveal that the prepared ceramic grains are uniform in size, dense in structure, and free of obvious pores and second phases. This indicates that the method for preparing a series of europium niobate-based microwave dielectric ceramic materials is feasible and effective, and that this method can yield relatively dense Europium niobate ceramics. 1-x Ca x Nb 1-x Mo x O4 microwave dielectric ceramic material.

[0053] Figure 4 As described in Example 5, using Eu 1-x Ca x Nb 1-x Mo x Simulation diagram of the substrate integrated resonant antenna fabricated from O4 (x = 0.32) (a: simulation structure design; b: return loss; c: gain and efficiency). The diagram shows that the designed antenna has a gain of 6.2 dBi at the center resonant frequency (3.67 GHz). 11 The radiation efficiency in the <-10dB region reaches over 90%. This indicates that the preparation method of the europium niobate-based microwave dielectric ceramic is feasible and effective, meeting the operational requirements of 5G communication technology.

[0054] Furthermore, this invention uses the cylindrical dielectric resonator method to evaluate the microwave dielectric properties. Specifically, it measures the dielectric constant ε of the solid material using the Hakki-Coleman method. r Measurements can only be taken at a single resonant frequency corresponding to the TE011 mode. To avoid conduction and radiation losses, the Q-value of the microwave dielectric ceramic sample can be measured using the resonant cavity method, where the sample is placed in a low-loss spaced cavity. The temperature coefficient of resonant frequency (τ) f The resonant frequency (RF) can be used to measure the stability of devices made from materials under different operating environments. It represents the "drift" of the resonant frequency as the temperature changes. The relationship between resonant frequency and temperature is as follows:

[0055]

[0056] In the formula, 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 ceramic are shown in Table 1.

[0057] Table 1. Microwave dielectric properties of the series of europium niobate-based microwave dielectric ceramics prepared in Examples 1-4

[0058]

[0059] As shown in Table 1, the prepared series of europium niobate-based microwave dielectric ceramic materials have high quality factors (Q×f) values ​​(64210~79950GHz) and low dielectric losses; their dielectric constants reach 18.2~16.2, and their resonant frequency temperature coefficient τ is [not specified]. f The temperature stability is good within the range of -32.3 to 6.9 ppm / ℃. Furthermore, the prepared series of Eu... 1- x Ca x Nb 1-x Mo x O4 microwave dielectric ceramics are all single-phase, not easily deliquescent, have a stable crystal structure, and are suitable for mass production. The resulting series of Eu... 1-x Ca x Nb 1-x Mo x O4 microwave dielectric ceramic materials exhibit high quality factor and low dielectric loss without the need for modification. Wide-range tuning of dielectric constant, quality factor, and temperature coefficient of resonant frequency is achieved, completing the serialization of europium niobate-based microwave dielectric ceramics and significantly improving the previously reported microwave dielectric properties of europium niobate microwave dielectric ceramics. Ultimately, europium niobate microwave dielectric ceramics with low dielectric constant, low loss, and near-zero temperature coefficient of resonant frequency are obtained.

[0060] For EuNbO4, introducing Mo, which has a smaller ionic radius, at the B site... 6+ ( CN=6) replaces Nb 5 + ( CN=6), while using a larger cation Ca at site A. 2+ (

[0061] CN=8) replaces Eu 3+ ( With CN=8, conventionally, the average bond length of BO bonds should shorten, and the bond length of AO bonds should stretch. However, X-ray diffraction analysis, i.e., refined XRD results, shows that AO bonds gradually compress and BO bonds gradually stretch in this structure. This unexpected effect will result in the substituted series of ceramics having a near-zero temperature coefficient of resonant frequency (τ). f Lower dielectric loss, i.e., higher Q×f value; where the BO bond is anomalously stretched, the B-site cation will also produce a rattling effect, thus leading to a series of ceramics with higher τ. f The value increases and approaches zero; simultaneously, the AO bond undergoes anomalous compression, and the A-site cation also experiences a compressed effect, leading to an increase in the Q×f value of the series of ceramics. Additionally, Ca... 2+ and Mo 6+Average ionic polarization Below Eu 3+ / Nb 5+ Average ionic polarization This will bring ε r The method achieves the regulation of three major performance parameters of europium niobate-based ceramics through the synergistic effect of "A / B site regulation + rattling effect + compressed effect".

[0062] This series of ceramics enhances the selectivity of device operating frequencies, simplifies heat dissipation design, and can be widely used in the fabrication of microwave devices such as dielectric antenna substrates, resonators, and filters with good temperature stability. The Eu materials prepared from these ceramics... 1-x Ca x Nb 1-x Mo x An integrated resonant antenna was fabricated on a substrate of O4 (x = 0.32) microwave dielectric ceramic, achieving a gain of 6.2 dBi at the center resonant frequency (3.67 GHz). 11 The radiation efficiency in the <-10dB region reaches over 90%.

[0063] The above description is merely a preferred embodiment of a series of europium niobate-based microwave dielectric ceramics and their preparation method according to the present invention. It should not be construed as limiting the scope of the present invention. Those skilled in the art can understand that implementing all or part of the above embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for wide-range tuning of the microwave dielectric properties of europium niobate-based microwave dielectric ceramics, characterized in that, This method achieves the regulation of three major performance parameters of EuNbO4 through the synergistic effect of "A / B site regulation + rattling effect + compressed effect". The europium niobate-based microwave dielectric ceramic has a monoclinic structure, with Ca ions replacing Eu ions at the A site and Mo ions replacing Nb ions at the B site. The chemical formula of the europium niobate-based microwave dielectric ceramic is: Eu 1-x Ca x Nb 1-x Mo x O4(0.1≤x≤0.32).

2. The method for wide-range adjustment of microwave dielectric properties of europium niobate-based microwave dielectric ceramics as described in claim 1, characterized in that, The preparation method of the europium niobate-based microwave dielectric ceramic includes the following steps: (1) According to Eu 1-x Ca x Nb 1-x Mo x Weigh Nb2O5, Eu2O3, CaCO3 and MoO3 raw material powders according to the atomic ratio of O4 (0.1≤x≤0.32); (2) The raw material powder is stirred and mixed, and then wet milled for the first time under the condition of adding ball milling media. Then it is dried, and then mixed again. A second wet milling is performed under the condition of ball milling media, and then a second drying is performed to obtain dried powder. Then it is pre-calcined in an atmospheric atmosphere at 1000°C for 4 hours to obtain pre-calcined powder. (3) Add a binder to the pre-fired powder to granulate, press it into shape, and finally sinter it in an atmospheric atmosphere at 1300-1400℃ for 6 hours to obtain europium niobate-based microwave dielectric ceramic.

3. The method for wide-range adjustment of microwave dielectric properties of europium niobate-based microwave dielectric ceramics as described in claim 2, characterized in that, In step (1) of the preparation method of europium niobate-based microwave dielectric ceramic, the time for the first wet milling treatment and the second wet milling treatment is 6 hours, and the ball milling medium used in both treatments is anhydrous ethanol.

4. The method for wide-range adjustment of microwave dielectric properties of europium niobate-based microwave dielectric ceramics as described in claim 2, characterized in that, In step (3) of the method for preparing europium niobate-based microwave dielectric ceramics, the binder is a polyvinyl alcohol solution with a mass concentration of 5%, and the amount of binder added is 3% of the total mass of the raw material powder.

5. The method for wide-range adjustment of microwave dielectric properties of europium niobate-based microwave dielectric ceramics as described in claim 4, characterized in that, In step (1) of the preparation method of the europium niobate-based microwave dielectric ceramic, according to Eu 0.9 Ca 0.1 Nb 0.9 Mo 0.1 The ingredients are prepared in an atomic ratio of O4, and the sintering temperature in step (3) is 1400℃.

6. The method for wide-range adjustment of microwave dielectric properties of europium niobate-based microwave dielectric ceramics as described in claim 4, characterized in that, In step (1) of the preparation method of the europium niobate-based microwave dielectric ceramic, according to Eu 0.8 Ca 0.2 Nb 0.8 Mo 0.2 The ingredients are prepared in an atomic ratio of O4, and the sintering temperature in step (3) is 1375℃.

7. The method for wide-range adjustment of microwave dielectric properties of europium niobate-based microwave dielectric ceramics as described in claim 4, characterized in that, In step (1) of the preparation method of the europium niobate-based microwave dielectric ceramic, according to Eu 0.7 Ca 0.3 Nb 0.7 Mo 0.3 The ingredients are prepared in an atomic ratio of O4, and the sintering temperature in step (3) is 1350℃.

8. The method for wide-range adjustment of microwave dielectric properties of europium niobate-based microwave dielectric ceramics as described in claim 4, characterized in that, In step (1) of the preparation method of the europium niobate-based microwave dielectric ceramic, according to Eu 0.68 Ca 0.32 Nb 0.68 Mo 0.32 The ingredients are prepared in an atomic ratio of O4, and the sintering temperature in step (3) is 1350℃.

9. A method utilizing the Eu as described in claim 8 0.68 Ca 0.32 Nb 0.68 Mo 0.32 A substrate-integrated resonant antenna designed with O4 microwave dielectric ceramic material, characterized in that... The substrate-integrated resonant antenna includes: a dielectric resonant antenna, a substrate, a rectangular slotted microstrip coupling groove, and a metal feed line. The dielectric resonant antenna is composed of Eu... 1-x Ca x Nb 1-x Mo x The antenna is made of O4 (x = 0.32) microwave dielectric ceramic material. A substrate is tightly fixed below the dielectric resonant antenna, which is located directly above the substrate. A rectangular slot is provided in the center of the substrate, which serves as a microstrip coupling slot to isolate the feed network at the bottom of the substrate and avoid coupling losses. A layer of copper is coated on the upper surface of the substrate as a metal ground, and a metal feed line is provided on the lower surface of the substrate. The metal feed line serves as a conductor to conduct electricity.

10. The substrate integrated resonant antenna as described in claim 9, characterized in that, The dielectric resonant antenna has a center frequency of 3.67 GHz and is a cylindrical structure with a height of 8.06 mm and a diameter of 16.4 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 7.01 mm and a width of 2.28 mm. The metal feed line has a length of 29.8 mm and a width of 1.91 mm, with one end flush with the edge of the substrate and the other end extending into the middle of the substrate.

Images