WO2023160504A1 - Dielectric ceramic, dielectric ceramic material, filter, radio frequency unit, and communication device - Google Patents

Abstract

The present application provides a dielectric ceramic, having a crystal phase of a tungsten bronze structure, and comprising Ba, Nd, Eu, Ti, Al and O elements, wherein Nd in Ba6-3xNd8+2xTi18O54 ceramic is replaced with Eu element, and part of Ti in Ba6-3xNd8+2xTi18O54 ceramic is replaced with Al element, wherein Eu replaces 10% or less of Nd by moles. The present application further provides a microwave dielectric ceramic material, a dielectric filter comprising the microwave dielectric ceramic material, and a radio frequency unit and a communication device comprising the dielectric filter. By replacing part of Nd in Ba6-3xNd8+2xTi18O54 ceramic with Eu element, and replacing part of Ti with Al element, excellent comprehensive microwave dielectric properties of dielectric ceramic materials are achieved, and a high dielectric constant, a high Qf value, and a near-zero temperature coefficient of resonant frequency τf are achieved.

Description

Dielectric ceramics, dielectric ceramic materials, filters, radio frequency units and communication equipment

Cross References to Related Applications

This application claims the priority of the Chinese patent application with the application number 202210171618.9 and the application name "dielectric ceramics, dielectric ceramic materials, filters, radio frequency units and communication equipment" filed on February 24, 2022, the entire content of which Incorporated herein by reference.

technical field

The present application relates to a dielectric ceramic, a microwave dielectric ceramic material, a dielectric filter including the microwave dielectric ceramic material, a radio frequency unit and a communication device including the dielectric filter.

Background technique

The filter is one of the core components of the radio frequency unit, which is used to pass specific frequency components in the signal and greatly attenuate other frequency components. In 5G massive antenna (Massive MIMO) technology, the number of antennas and filters has increased dramatically, and the high integration and miniaturization of 5G base stations have higher requirements for the size and loss of filters. Dielectric ceramics have a high dielectric constant, which is conducive to the small size and light weight of the filter. At the same time, the dielectric ceramic material has a high Qf value, which helps to greatly reduce the insertion loss of the dielectric ceramic filter. Therefore, the dielectric ceramic filter It will become the mainstream filter of 5G base stations.

With the increase in the number of transceiver channels of 5G base stations, higher requirements are put forward for the miniaturization and low insertion loss of dielectric filters, which have higher dielectric constants (Dk value is greater than or equal to 60, and the dielectric constant generally refers to the relative dielectric constant, which characterizes the dielectric Dielectric properties of materials or physical parameters of polarization properties), high quality coefficient (generally refers to Qf value, dielectric loss tanδ at microwave frequency, Q is 1/tanδ, f is resonance frequency, Qf value is Q value and resonance The product of the frequency f) and the temperature coefficient of the zero resonant frequency (to measure the stability of the resonant frequency in a certain temperature range, that is, the change of the resonant frequency in a specific temperature range) are necessary.

Contents of the invention

The first aspect of the embodiment of the present application provides a dielectric ceramic, which has a tungsten bronze structure crystal phase, including Ba, Nd, Eu, Ti, Al and O elements, which are Eu elements instead of Ba _6-3x Nd _8+2x Ti Nd in ₁₈ O ₅₄ ceramics, and part of Ti in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics is replaced by Al element, wherein Eu replaces less than or equal to 10 mol% of Nd.

In this application, Eu elements replace part of Nd in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics, and Al elements replace part of Ti in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics, so as to achieve The material has excellent comprehensive microwave dielectric properties, with high dielectric constant, high Qf value, and zero resonance frequency temperature coefficient τ _f .

In the embodiment of the present application, the molecular formula of the dielectric ceramic is Ba _6-3x (Nd _1-z Eu _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y <4, 0<z≤0.1.

It can be clearly understood from the molecular formula that the range of the molar substitution content of Eu and Al elements in the dielectric ceramic, for example, Eu substitutes less than or equal to 10 mole percent of Nd in the Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramic.

In the embodiment of the present application, the molecular formula of the dielectric ceramic is Ba _6-3x (Nd _1-z Eu _z ) _8+2x+y/3 Ti _18-y Aly _{O 54} , where 0.6 <x<0.8, 0.1<y≤3, 0<z≤0.1.

It can be clearly understood from the molecular formula that the range of the molar substitution content of Eu and Al elements in the dielectric ceramic, for example, Eu substitutes less than or equal to 10 mole percent of Nd in the Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramic.

In the embodiment of the present application, the dielectric ceramic further includes Sm element, and the Sm element and the Eu element replace less than or equal to 30 mol% of Nd in the Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramic.

In the embodiment of the present application, the dielectric ceramic has a molecular formula of Ba _6-3x [Nd _1-z (Sm _1-a Eu _a ) _z ] _8+2x+y/3 Ti _18-y Aly _{O 54} , wherein 0.6<x<0.8, 0.1<y<4, 0<z≤0.3, 0<a≤0.1.

It can be clearly understood from the molecular formula that the molar content range of Eu, Sm, and Al elements in the dielectric ceramics, for example, Eu and Sm jointly replace Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics to less than or equal to 30% moles of Nd, and the range of molar ratios of both Eu and Sm.

In the embodiment of the present application, the dielectric ceramic has a molecular formula of Ba _6-3x (Nd _1-z (Sm _1-a Eu _a ) _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where 0.6<x<0.8,0.1<y<4,0<z≤0.3,0<a≤0.1.

It can be clearly understood from the molecular formula that the molar content range of Eu, Sm, and Al elements in the dielectric ceramics, for example, Eu and Sm jointly replace Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics to less than or equal to 30% moles of Nd, and the range of molar ratios of both Eu and Sm.

In the implementation manner of the present application, the dielectric constant of the dielectric ceramic is 63-67, and the Qf value is >14000 GHz.

In the dielectric ceramic of the present application, part of Nd in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramic is replaced by Eu element, and part of Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramic is replaced by Al element Ti, so as to realize the excellent comprehensive microwave dielectric properties of the material, with high dielectric constant and high Qf value.

In the embodiment of the present application, the resonant frequency temperature coefficient τ _f of the dielectric ceramic satisfies -3<τ _f <3ppm/°C, |Δτ _f /ΔT|<30ppb/°C ² at -40°C≤T≤+105°C within the temperature range.

The dielectric ceramic of the present application has a resonant frequency temperature coefficient τ _f that tends to zero.

The second aspect of the embodiment of the present application provides a microwave dielectric ceramic material, including dielectric ceramics, the dielectric ceramics have a tungsten bronze structure crystal phase, including Ba, Nd, Eu, Ti, Al and O elements, which are Eu Elements replace Nd in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics, and Al elements replace part of Ti in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics, where Eu replaces less than or equal to 10% Moore's Nd.

This application aims at the low Qf value of the Ba _6-3x Ln _8+2x Ti ₁₈ O ₅₄ tungsten bronze system at microwave frequencies. By selecting appropriate rare earth elements and doping with asymmetric elements, the system maintains a high dielectric constant, Under the premise of low resonance frequency temperature coefficient, its Qf value is greatly improved.

In the implementation manner of the present application, the microwave dielectric ceramic material includes at least one of the following dielectric ceramics:

Dielectric ceramics with molecular formula Ba _6-3x (Nd _1-z Eu _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y<4, 0<z≤0.1 ;

Dielectric ceramics with molecular formula Ba _6-3x (Nd _1-z Eu _z ) _8+2x+y/3 Ti _18-y Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y≤3, 0<z ≤0.1;

Dielectric ceramics with molecular formula Ba _6-3x [Nd _1-z (Sm _1-a Eu _a ) _z ] _8+2x+y/3 Ti _18-y Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y<4,0<z≤0.3,0<a≤0.1;

Dielectric ceramics with molecular formula Ba _6-3x (Nd _1-z (Sm _1-a Eu _a ) _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y< 4. 0<z≤0.3, 0<a≤0.1.

From the molecular formula, it can be clearly understood that the range of the molar substitution content of Eu, Sm, Al and other elements in the dielectric ceramics.

In the embodiment of the present application, the microwave dielectric ceramic material further includes at least one of the following crystal phases: Al ₂ O ₃ , (Nd,Eu) ₂ Ti ₂ O ₇ , BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ and TiO ₂ .

In the preparation process of microwave dielectric ceramic materials, the purpose is to obtain a powder with a tungsten bronze structural phase, but a small amount of other crystal phases, such as (Nd,Eu) ₂ Ti ₂ , may also be generated while obtaining a powder with a tungsten bronze structural phase. At least one of O ₇ , BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ , and a small amount of unreacted raw materials Al ₂ O ₃ and TiO ₂ .

The third aspect of the embodiment of the present application provides a dielectric filter, including a dielectric ceramic body, an input terminal and an output terminal connected to the dielectric ceramic body, and the material of the dielectric ceramic body includes the material described in the first aspect of the embodiment of the present application. The dielectric ceramic mentioned above or the microwave dielectric ceramic material described in the second aspect of the embodiment of the present application.

The dielectric filter has good performance due to the use of a dielectric ceramic body with a high relative permittivity, a high quality coefficient Qf value, and a temperature coefficient τf close to 0ppm/°C. The dielectric filter has the advantages of miniaturization, low insertion advantage of loss.

A fourth aspect of the embodiment of the present application provides a radio frequency unit, including the dielectric filter described in the third aspect of the embodiment of the present application.

A fifth aspect of the embodiment of the present application provides a communication device, including the dielectric filter described in the third aspect of the embodiment of the present application.

Description of drawings

FIG. 1 is a scanning electron microscope image of a dielectric ceramic according to an embodiment of the present application.

FIG. 2 is an X-ray diffraction diagram of a dielectric ceramic according to an embodiment of the present application.

Fig. 3 is a schematic diagram of a dielectric filter according to an embodiment of the present application.

Description of main component symbols

Dielectric filter 100

Dielectric Ceramic Body 10

Input terminal 11

Output terminal 13

Detailed ways

Embodiments of the present application are described below with reference to the drawings in the embodiments of the present application. The data range values recorded in this application shall include the end values unless otherwise specified.

With the increase in the number of transceiver channels in 5G base stations, higher requirements are put forward for the miniaturization and low insertion loss of dielectric filters, thus requiring dielectric materials to have higher dielectric constants, high Qf values, and zero-resonant frequency temperature coefficient τ _f .

Ba _6-3x Ln _8+2x Ti ₁₈ O ₅₄ is a high dielectric material with a tungsten bronze structure crystal phase. In this structure, titanium oxide octahedrons (TiO ₆ ) share vertices and connect in a three-dimensional space to form an underfilled tungsten bronze structure. There are three different shapes of voids in each unit cell. According to the order of the voids from large to small, they are pentagonal voids (A2), quadrangular rhomboid voids (A1) and triangular voids (C). Among them, Ba ²⁺ with the largest ionic radius Generally occupy the largest pentagonal void; the smaller quadrangular rhombus void is mainly occupied by Ln ³⁺ , and Ba ²⁺ will partially occupy the quadrangular rhombus void after filling the pentagonal void; the smallest triangular void is not filled Type tungsten bronze structure is empty, generally not occupied by ions. It is precisely because of the possibility that the quadrangular rhombohedral voids can be shared by two types of ions, "Ba ²⁺ " and "Ln ³⁺ ", makes this material system present a complex heterogeneous isomorphism.

By substituting tetragonal rhombohedral voids, pentagonal voids, or B-site Ti atoms of (TiO ₆ ), the dielectric constant of the material system can be adjusted to vary between 55 and 90, and a lower or even approaching Resonant frequency temperature coefficient at 0ppm/°C. Note: The resonant frequency temperature coefficient is a parameter of thermal stability, which refers to the degree of resonant frequency drift of microwave dielectric ceramic materials when the temperature changes.

Ba _6-3x Ln _8+2x Ti ₁₈ O ₅₄ system high dielectric material has a low Qf value at microwave frequency. Currently, the Qf value of this system material is about 10000-12000 GHz, although it can meet the needs of some specific scenarios. However, for the 5G base station's demand for low insertion loss of the dielectric filter, a higher Qf value is required to meet it.

This application aims at the technical problem that the Qf value of the Ba _6-3x Ln _8+2x Ti ₁₈ O ₅₄ tungsten bronze system cannot meet the requirements of 5G base station filters. Under the premise of high dielectric constant and low resonant frequency temperature coefficient, its Qf value is greatly improved.

Based on the continuous research on the Ba _6-3x Ln _8+2x Ti ₁₈ O ₅₄ tungsten bronze system in academia and industry, it is clear that the Qf value in the microwave band is strongly related to the lattice stress and the TiO ₆ octahedron tilt angle, and the element Doping modification can change the above factors. Among the known doping modification methods, it is found that Al element doping modification has the most obvious effect on the Qf value of Ba _6-3x Ln _8+2x Ti ₁₈ O ₅₄ material, and there are five ways of Al element doping, Listed in Table 1, wherein V in the chemical formula in Table 1 represents a vacancy.

Table 1

In the first way of Al doping, Al ³⁺ ions replace Ti ⁴⁺ ions, and the charge balance is maintained by an additional 1/3 Nd ³⁺ ions entering the A1-type sublattice. The second way of Al element doping, Al ³⁺ ions replace Ti ⁴⁺ ions, and the charge balance is entered by the extra 1/3 Nd ³⁺ and extra 1/2 Ba ²⁺ ions into the A1-type subcrystal of the system crystal grid to maintain. In the third way of Al doping, Al ³⁺ ions replace Ti ⁴⁺ ions, and the charge balance is maintained by the addition of 1/2 Ba ²⁺ ions into the A1-type sublattice. In the fourth way of Al element doping, 3/4 Al ³⁺ ions replace Ti ⁴⁺ ions and 1/4 Al ³⁺ ions enter the vacant C sites of the structure, thereby balancing the charge. In the fifth way of Al doping, Al ³⁺ ions replace Ti ⁴⁺ ions, and the charge balance is maintained by entering the oxygen vacancies of the oxygen sublattice.

Through the preparation, testing and analysis of a large number of samples, it is found that the Al doping of Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ (Ln chooses Nd) system ceramics can obtain a high Qf value with a resonant frequency temperature coefficient (τ _f ) close to zero Formulations, in particular by the 1st and 4th doping methods or by a combination of the two doping methods; some examples of formulations based on the above-mentioned doping methods are listed in Table 2.

Table 2

In addition, it can be seen from Table 2 that although the Al doping of Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics can significantly reduce the value of _τf , and even obtain a high-Qf formulation with a value of _τf close to zero, but | _Δτf /ΔT| is kept above 30ppb/°C ² , so in order to reduce |Δτ _f /ΔT| to below 30ppb/°C ² , other doping elements (such as Sm, Eu and other elements) can be used to partially replace Ba, and the |Δτ _f It is most effective to lower the /ΔT| value to below 30ppb/°C ² .

The application provides a dielectric ceramic, which has a crystal phase of tungsten bronze structure, including Ba, Nd, Eu, Ti, Al and O elements, which are Eu elements replacing Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics. Less than or equal to 10% (mol percent) of Nd, and Al element replaces part of Ti in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics, so as to achieve excellent comprehensive microwave dielectric properties of the material, with high dielectric Constant, high Qf value, and zero resonant frequency temperature coefficient τ _f .

In some embodiments, the molecular formula of the dielectric ceramic is Ba _6-3x (Nd _1-z Eu _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , wherein 0.6<x<0.8, 0.1<y< 4. 0<z≤0.1. From the molecular formula, it can be clearly understood the range of the substitution molar content of elements such as Eu and Al in the dielectric ceramic. The molecular formula of the dielectric ceramic can be converted according to the valence state balance, Eu and Nd have the same valence state, then Eu replaces Nd in the Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics less than z mole percentage expressed as (Nd _1-z Eu _z ) _8+2x ; y mole parts of Al replace part of Ti, in order to satisfy the valence balance, Ti needs to be reduced by 3y/4 mole parts, which is expressed as Ti _18-3y/4 Al _y .

In some embodiments, the molecular formula of the dielectric ceramic is Ba _6-3x (Nd _1-z Eu _z ) _8+2x+y/3 Ti _18-y Aly _{O 54} , where 0.6<x<0.8, 0.1< y≤3, 0<z≤0.1. The molecular formula of the dielectric ceramic can be converted according to the stoichiometric ratio. If y molar parts of Al replace the y molar parts of Ti in the Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics, then the corresponding reduction of y molar parts of Ti is represented by For Ti _{18-y Aly} , Eu replaces Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics with less than z mole percent of Nd expressed as (Nd _1-z Eu _z ) _8+2x , and in order to make the overall If the valence state is balanced, then (Nd _1-z Eu _z ) needs to increase y/3 mole fraction to express as (Nd _1-z Eu _z ) _8+2x+y/3 .

From the z values in the above two molecular formulas, it can be seen that Eu replaces less than or equal to 10 mole percent of Nd in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics.

The dielectric ceramic may further include a Sm element, and the Sm element and the Eu element replace 30% or less of Nd by mole in the Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramic.

In some embodiments, the dielectric ceramic has a molecular formula of Ba _6-3x [Nd _1-z (Sm _1-a Eu _a ) _z ] _8+2x+y/3 Ti _18-y Aly _{O 54} , where 0.6 <x<0.8, 0.1<y<4, 0<z≤0.3, 0<a≤0.1. The molecular formula of the dielectric ceramic can be converted according to the stoichiometric ratio. If y molar parts of Al replace the y molar parts of Ti in the Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics, then the corresponding reduction of y molar parts of Ti is represented by For Ti _18-y Al _y , Eu and Sm jointly replace Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics with less than z mole percentage of Nd expressed as (Nd _1-z Eu _z ) _8+2x , and in order to make The overall valence state of the molecular formula is balanced, then [Nd _1-z (Sm _1-a Eu _a ) _z ] needs to increase y/3 mole parts and express it as [Nd _1-z (Sm _1-a Eu _a ) _z ] _{8+2x +y/3} .

In some embodiments, the dielectric ceramic has a molecular formula of Ba _6-3x (Nd _1-z (Sm _1-a Eu _a ) _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where 0.6<x <0.8, 0.1<y<4, 0<z≤0.3, 0<a≤0.1. The molecular formula of the dielectric ceramic can be converted according to the valence balance. Eu, Sm and Nd have the same valence, then Eu and Sm jointly replace less than z mole percentage of Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics Nd is expressed as (Nd _1-z (Sm _1-a Eu _a ) _z ) _8+2x ; y mole parts of Al replace part of Ti, in order to meet the valence balance Ti needs to be reduced by 3y/4 mole parts, it is expressed as Ti _18-3y/4 Al _y .

It can be seen from the z value of the above two molecular formulas that Eu and Sm jointly replace the Nd in the Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics less than or equal to 30% by mole. It can be known from the a value that both Eu and Sm range of molar ratios.

The dielectric constant of the above-mentioned dielectric ceramic is 63-67, and the Qf value is >14000GHz. The resonant frequency temperature coefficient (τ _f ) of the dielectric ceramic satisfies -3<τ _f <3ppm/°C, and |Δτ _f /ΔT|<30ppb/°C ² in the temperature range of -40°C≤T≤+105°C.

The present application also provides a microwave dielectric ceramic material, including the main crystal phase of the tungsten bronze structural phase, and the main crystal phase is at least one of the above-mentioned dielectric ceramics, that is, at least one of the following:

Dielectric ceramics with molecular formula Ba _6-3x (Nd _1-z Eu _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y<4, 0<z≤0.1 ;

Dielectric ceramics with molecular formula Ba _6-3x (Nd _1-z Eu _z ) _8+2x+y/3 Ti _18-y Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y≤3, 0<z ≤0.1;

Dielectric ceramics with molecular formula Ba _6-3x [Nd _1-z (Sm _1-a Eu _a ) _z ] _8+2x+y/3 Ti _18-y Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y<4,0<z≤0.3,0<a≤0.1;

Dielectric ceramics with molecular formula Ba _6-3x (Nd _1-z (Sm _1-a Eu _a ) _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y< 4. 0<z≤0.3, 0<a≤0.1.

In some embodiments, the microwave dielectric ceramic material may also include a small amount of at least one of the following crystal phases: Al ₂ O ₃ , (Nd,Eu) ₂ Ti ₂ O ₇ , BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ and TiO ₂ .

The purpose of this application is to improve the Qf value and resonant frequency temperature coefficient of Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramic materials. The preparation method of dielectric ceramics specifically includes the following steps:

(1) Ingredients: Raw materials can be high-purity powders such as BaCO ₃ , TiO ₂ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ and Al ₂ O ₃ , but not limited thereto. Measuring ratio ingredients;

(2) ball milling, to grind the raw material powder into a required particle size, for example less than 100 mesh;

(3) High-temperature solid-phase synthesis to obtain a powder with a tungsten bronze structural phase, generally heat-treated in air at 1100°C to 1200°C for 3 to 10 hours;

(4) Secondary ball milling to obtain tungsten bronze structural phase powder with required particle size;

(5) Sintering: Add the tungsten bronze structural phase powder to the binder and mix evenly, then press it into a green body of the desired shape, then sinter the green body at 1360 ° C ~ 1420 ° C, and then anneal at 1100 ° C for 5 ~ 10 hours.

Take Ba _6-3x (Nd _1-z Eu _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ in Table 2 as an example, where x=0.85, y=1, z=0.15; The weighed raw material powder is mixed with yttrium stabilized zirconia balls (grinding media) and a certain amount of pure water in a planetary mixer for 12 hours, and the obtained slurry is placed in a blast oven to dry, and then the dried powder Sieve through a 100-mesh nylon sieve, place the sieved powder in a 99% Al ₂ O ₃ ceramic crucible, and heat-treat it in air at 1150°C for 10 hours, in order to obtain a powder with a tungsten bronze structure phase (to obtain tungsten The powder of the bronze structure phase may also generate a small amount of other crystal phases, such as at least one of (Nd,Eu) ₂ Ti ₂ O ₇ , BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ , and a small amount of unreacted Raw materials Al ₂ O ₃ and TiO ₂ ), after that, use the planetary ball mill to mill the synthesized powder for 7 hours again, dry and sieve the obtained slurry; add a small amount of polyvinyl alcohol aqueous solution binder to the dried powder And mix evenly, after that, use a uniaxial press to press the powder into a green disc with a diameter of 7mm to 13mm and a thickness of 3.5mm to 6.5mm, and sinter at 1360°C to 1420°C, and then sinter at 1100°C Anneal for 5-10 hours to obtain the sample. Please refer to the scanning electron microscope image of the sample in Figure 1, it can be seen that the microstructure of the obtained sample is dense, the crystal grains are rod-shaped, and the uniform size is about 3-5 μm. Please refer to the X-ray diffraction pattern of the sample in Figure 2, it can be seen that the prepared sample is a crystal phase of pure tungsten bronze structure.

The microwave dielectric properties of the sample are measured in the frequency range of 1-6.8 GHz: for the test sample whose diameter to thickness ratio is between 1.8 and 2.2, the dielectric constant of the microwave band is tested by the Hakki-coleman method, and the closed Cavity resonance method to test Qf value and resonant frequency temperature coefficient; measured microwave dielectric properties: dielectric constant 66.6, Qf = 15700GHz, τ _f = +3.0ppm/℃ and |Δτ _f /ΔT| = 28ppb/℃ ² in -40℃≤T≤+105℃ temperature range.

In another embodiment in Table 2, Ba _6-3x (Nd _1-z Eu _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where x=0.85, y=4, z=0.15, the same The preparation process conditions were prepared and tested by the same test method, which can achieve a dielectric constant of 66.5, Qf = 15500GHz, τ _f = -1.06ppm/°C and |Δτ _f /ΔT| = 23ppb/°C ² at -40°C ≤T≤+105℃ temperature range.

As shown in FIG. 3 , the present application also provides a dielectric filter 100 , including a dielectric ceramic body 10 , an input terminal 11 and an output terminal 13 connected to the dielectric ceramic body 10 . The material of the dielectric ceramic body 10 is the microwave dielectric ceramic material mentioned above. In this embodiment, the dielectric ceramic body 10 is in the shape of a rectangular block, but it is not limited thereto, and the specific shape can be designed according to the needs of the product. In this embodiment, the input terminal 11 and the output terminal 13 are protruded on the surface of the dielectric ceramic body 10 at intervals, and the input terminal 11 and the output terminal 13 can be conductive needles and pass through solder (such as solder ) is connected to the surface of the dielectric ceramic body 10, and shallower grooves (not shown in the figure) can also be arranged in the regions where the input terminals 11 and the output terminals 13 are arranged, and solder is filled in the grooves. The dielectric ceramic body 10 is provided with a plurality of strip-shaped through holes (not shown) passing through the dielectric ceramic body 10 and a plurality of circular blind holes (not shown) not penetrating the dielectric ceramic body 10 , The shape and arrangement of through holes and blind holes can also be designed according to the needs of the product. The dielectric filter 100 has good performance due to the use of a dielectric ceramic body 10 with a high relative permittivity, a high quality factor Qf, and a temperature coefficient τf close to 0 ppm/°C.

The present application also provides a radio frequency unit, including the dielectric filter.

The present application also provides a communication device, including the dielectric filter.

It should be noted that the above is only a specific implementation of the application, but the scope of protection of the application is not limited thereto, and any person familiar with the technical field can easily think of changes or substitutions within the scope of the technology disclosed in the application , should be covered within the protection scope of the present application; in the case of no conflict, the implementation modes and the features in the implementation modes of the application can be combined with each other. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims (14)

1. A kind of dielectric ceramic, has tungsten bronze structure crystal phase, is characterized in that, comprises Ba, Nd, Eu, Ti, Al and O element, and it is that Eu element replaces Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics Nd, and Al element replaces part of Ti in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics, wherein Eu replaces less than or equal to 10 mol% of Nd.
2. The dielectric ceramic according to claim 1, wherein the molecular formula of the dielectric ceramic is Ba _6-3x (Nd _1-z Eu _z ) _8+2x Ti _{18-3y/4 Aly} O ₅₄ , wherein 0.6<x<0.8, 0.1<y<4, 0<z<0.1.
3. The dielectric ceramic according to claim 1, wherein the molecular formula of the dielectric ceramic is Ba _6-3x (Nd _1-z Eu _z ) _8+2x+y/3 Ti _18-y Aly _{O 54} , where 0.6<x<0.8, 0.1<y≤3, 0<z≤0.1.
4. The dielectric ceramic according to claim 1, wherein the dielectric ceramic further comprises Sm element, and the Sm element and the Eu element replace the Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramic 30 mol% or less of Nd.
5. The dielectric ceramic according to claim 4, wherein the dielectric ceramic has a molecular formula of Ba _6-3x [Nd _1-z (Sm _1-a Eu _a ) _z ] _8+2x+y/3 Ti _18-y Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y<4, 0<z≤0.3, 0<a≤0.1.
6. The dielectric ceramic according to claim 4, wherein the dielectric ceramic has a molecular formula of Ba _6-3x (Nd _1-z (Sm _1-a Eu _a ) _z ) _8+2x Ti _{18-3y/ 4} Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y<4, 0<z≤0.3, 0<a≤0.1.
7. The dielectric ceramic according to any one of claims 1 to 6, characterized in that, the dielectric constant of the dielectric ceramic is 63-67, and the Qf value is >14000 GHz.
8. The dielectric ceramic according to any one of claims 1 to 7, characterized in that the resonant frequency temperature coefficient τ _f of the dielectric ceramic satisfies -3<τ _f <3ppm/°C, |Δτ _f /ΔT| <30ppb/°C ² in the temperature range of -40°C≤T≤+105°C.
9. A microwave dielectric ceramic material, comprising a dielectric ceramic, is characterized in that the dielectric ceramic has a tungsten bronze structure crystal phase, including Ba, Nd, Eu, Ti, Al and O elements, which are Eu elements replacing Ba _6- Nd in _3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics, and part of Ti in Ba _6-3x Nd _8+2x Ti ₁₈ O ₅₄ ceramics replaced by Al element, wherein Eu replaces less than or equal to 10 mol% of Nd.
10. The microwave dielectric ceramic material according to claim 9, wherein the microwave dielectric ceramic material comprises at least one of the following dielectric ceramics:

    Dielectric ceramics with molecular formula Ba _6-3x (Nd _1-z Eu _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y<4, 0<z≤0.1 ;

    Dielectric ceramics with molecular formula Ba _6-3x (Nd _1-z Eu _z ) _8+2x+y/3 Ti _18-y Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y≤3, 0<z ≤0.1;

    Dielectric ceramics with molecular formula Ba _6-3x [Nd _1-z (Sm _1-a Eu _a ) _z ] _8+2x+y/3 Ti _18-y Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y<4,0<z≤0.3,0<a≤0.1;

    Dielectric ceramics with molecular formula Ba _6-3x (Nd _1-z (Sm _1-a Eu _a ) _z ) _8+2x Ti _18-3y/4 Al _y O ₅₄ , where 0.6<x<0.8, 0.1<y< 4. 0<z≤0.3, 0<a≤0.1.
11. The microwave dielectric ceramic material according to claim 9 or 10, characterized in that the microwave dielectric ceramic material further comprises at least one of the following crystal phases: Al ₂ O ₃ , (Nd,Eu) ₂ Ti ₂ O ₇ , BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ and TiO ₂ .
12. A dielectric filter, comprising a dielectric ceramic body, an input terminal connected to the dielectric ceramic body, and an output terminal, characterized in that the material of the dielectric ceramic body includes any one of claims 1 to 8 Dielectric ceramics or the microwave dielectric ceramic material according to any one of claims 9 to 11.
13. A radio frequency unit, characterized in that the radio frequency unit comprises the dielectric filter according to claim 12.
14. A communication device, characterized in that the communication device comprises the dielectric filter according to claim 12.