Low-temperature sintered high-q dielectric constant microwave dielectric ceramic material and preparation method thereof

Abstract

The application relates to a low-temperature sintered high-Q-value microwave dielectric ceramic material and a preparation method thereof. The chemical composition of the high-Q-value microwave dielectric ceramic material is (1-x)(Mg 0.9 Zn 0.05 Mn 0.05 )TiO3‑xBa 0.9 Nd 0.2 / 3Zr 0.95 Sn 0.05 O3, wherein 0.1<=x<=0.9.

Description

Technical Field

[0001] This invention relates to a low-temperature sintering microwave dielectric ceramic material with high Q value dielectric constant and its preparation method. It can be used in devices such as TE mode, TM mode, and TEM mode dielectric resonators, dielectric duplexers, dielectric substrates, and 5G dielectric filters in the modern communication field, and belongs to the field of electronic information functional ceramic materials. Background Technology

[0002] The new 5G antenna brings about a significant increase in the use of filters: With the advent of the 5G era, the demand for base station antenna materials has changed significantly: 1) As the AAU will support more channels and the device integration is higher, the complexity of ceramic dielectric filter processes and the value of products will increase accordingly; 2) The number of filters used in the AAU is greater than that in the 4G RF front end; 3) The 5G operating frequency band is higher and the transmission power is greater, which places higher demands on the transmission loss and heat dissipation performance of filter materials.

[0003] In the 5G era, traditional metal cavity filters cannot achieve high suppression for system compatibility, while ceramic dielectric material cavities can solve these problems. Microwave dielectric ceramic filters are an important solution for future 5G. Developing microwave dielectric ceramics with standardized dielectric constants and excellent performance has always been a key research topic both domestically and internationally. Currently, MgTiO3-Ca... 0.6 La 0.8 / 3 The problems with TiO3-based microwave materials are: firstly, the sintering temperature is too high, exceeding 1350℃, which easily leads to excessively large grains and high energy consumption; secondly, the sintering range is narrow, resulting in low product yield; and thirdly, the Qf value of the material is too low, below 50000GHz, which leads to high insertion loss of resonators or filters, affecting device performance. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a microwave dielectric ceramic with a high quality factor, near-zero frequency temperature coefficient, and a sintering temperature below 1300℃ that can be ceramicized in an air atmosphere. It not only possesses excellent microwave properties but also has a stable preparation and production process.

[0005] On one hand, the present invention provides a high-Q value microwave dielectric ceramic material with a dielectric constant, wherein the chemical composition of the high-Q value microwave dielectric ceramic material is (1-x)(Mg 0.9 Zn 0.05 Mn 0.05 TiO3-xBa 0.9 Nd 0.2 / 3Zr 0.95 Sn 0.05 O3, where 0.1≤x≤0.9.

[0006] In the microwave dielectric ceramic material prepared by this invention, since the radii of Zn ions and Mg ions are close, the main function of doping with an appropriate amount of ZnO is to replace some Mg ions, reduce porosity defects, and lower the sintering temperature. The main function of doping with MnO2 is to overcome insufficient oxygen concentration during sintering, prevent Ti ion reduction, and promote liquid phase sintering to improve the quality factor. The function of doping with SnO is to replace some Ti ions to prevent titanium-rich aggregation and lower the sintering temperature. The purpose of three ball millings is to reduce the particle size distribution, and the purpose of the two solid-phase reactions is to allow the excess free oxides to react fully to obtain a purer solid phase composition.

[0007] Ideally, 0.2 ≤ x ≤ 0.5.

[0008] Preferably, the Q×f value of the high Q value dielectric constant microwave dielectric ceramic material is 16000~100500, more preferably 55000~75000GHz;

[0009] The relative permittivity of the high-Q value microwave dielectric ceramic material is 17-40, preferably 18-30;

[0010] The resonant frequency temperature coefficient of the high Q value dielectric constant microwave dielectric ceramic material is ±50ppm / ℃, preferably ±10ppm / ℃.

[0011] The density of the high Q-value dielectric constant microwave dielectric ceramic material is above 99%.

[0012] Preferably, the high Q-value dielectric constant microwave dielectric ceramic material is prepared by sintering in air at 1200℃~1300℃.

[0013] On the other hand, the present invention provides a method for preparing a microwave dielectric ceramic material with a high Q value dielectric constant, comprising:

[0014] (1) Using MgO powder, ZnO powder, MnO2 powder, TiO2 powder, BaO powder, ZrO2 powder, SnO2 powder, and Nd2O3 powder as raw materials, according to the chemical formula (1-x)(Mg 0.9 Zn 0.05 Mn 0.05 TiO3-xBa 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 The molar ratio of O3 was weighed and mixed to obtain a mixed powder.

[0015] (2) The mixed powder is subjected to a first solid-phase synthesis and a second solid-phase synthesis to obtain the raw material powder;

[0016] (3) The raw material powder and binder are mixed and then granulated to obtain granulated powder;

[0017] (4) The granulated powder is pressed into shape and sintered in air at 1200℃~1300℃ for 6~10 hours to obtain a main crystalline phase of (Mg). 0.9 Zn 0.05 Mn 0.05 TiO3-Ba 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 O3 is a microwave dielectric ceramic material with high Q value and dielectric constant.

[0018] Preferably, the temperature of the first solid-phase synthesis is 1000℃~1100℃, and the synthesis time is 3~5 hours.

[0019] Preferably, the temperature of the secondary solid-phase synthesis is 1100℃~1200℃ and the temperature of the secondary solid-phase synthesis is greater than the temperature of the primary solid-phase synthesis, and the synthesis time is 3~5 hours.

[0020] Preferably, the binder is a polyvinyl alcohol solution with a concentration of 1-2 wt%; the ratio of the binder to the raw material powder is (6-10) mL: 1 g.

[0021] Preferably, the pressing pressure is 80-200 MPa, and more preferably 100 MPa.

[0022] The present invention has the following advantages:

[0023] Compared with existing undoped MgTiO3-CaLaTiO3-based microwave ceramics (sintering temperature above 1300℃ and relatively low Qf value), the high Q value microwave dielectric ceramic material of the present invention has a sintering temperature of ≤1300℃, preferably ≤1200℃, which has energy-saving advantages and excellent performance.

[0024] In this invention, the sintering conditions for microwave dielectric ceramic materials with high Q-value dielectric constants are simple, the sintering atmosphere is air, the sintering range is wide, the stability is high, and the quality factor is greatly improved, which has great practical value.

[0025] In this invention, the raw materials for the high Q-value dielectric constant microwave dielectric ceramic material are all domestically sourced, with moderate prices. The formula does not contain heavy metals, making it an environmentally friendly and pollution-free microwave dielectric ceramic.

[0026] In this invention, low-temperature sintered (Mg) 0.9 Zn 0.05 Mn 0.05 TiO3-Ba 0.9 Nd 0.2 / 3 Zr0 .95 Sn 0.05O3-based microwave dielectric ceramics, which significantly improve their Qf value while reducing raw material costs and exhibiting stable processing, have great scientific research value and market prospects. Attached Figure Description

[0027] Figure 1 The XRD analysis results are for the microwave dielectric ceramic material prepared in Example 3;

[0028] Figure 2 This is a SEM image of the microwave dielectric ceramic material prepared in Example 3. Detailed Implementation

[0029] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0030] In this invention, the composition of the low-temperature sintered high-Q dielectric constant microwave dielectric ceramic material can be (1-x)(Mg 0.9 Zn 0.05 Mn 0.05 TiO3-xBa 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 O3, where 0.1 ≤ x ≤ 0.9. The high Q-value dielectric constant microwave dielectric ceramic sintered at low temperature requires no additives and is prepared by sintering in air at a temperature between 1200℃ and 1300℃. Because the radii of Zn and Mg ions are close, Zn ions can replace some Mg ions without changing the Mg ion cell structure, lowering the melting point and sintering temperature of the system, thus acting as a sintering aid. Mn acts as a strong oxidizing agent, releasing oxygen during sintering to prevent Ti ion reduction, inhibiting the formation of black cores in the sample, and improving the Q-value. The substitution of Ba with trivalent lanthanide ions (Nd) can significantly improve the Q-value of BaTiO3, attributed to the ordered arrangement caused by Nd substitution of A-site Ba ions. Sn substitution of some Zr can generate a liquid phase earlier, lowering the sintering temperature; 0.05 is the upper limit of Sn's solid solubility in Zr, and any excess or deficiency will reduce the Q-value of the system.

[0031] This invention employs a traditional solid-state synthesis process, using chemical raw materials, with low sintering temperature, low cost, no pollution, and ease of mass production. The following exemplarily illustrates a method for preparing microwave dielectric ceramic materials with high Q-value dielectric constant.

[0032] Using MgO powder, ZnO powder, MnO2 powder, TiO2 powder, BaO powder, ZrO2 powder, SnO2 powder, and Nd2O3 powder as raw materials, according to the chemical formula (1-x)(Mg 0.9 Zn 0.05 Mn 0.05TiO3-xBa 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 The molar ratio of O3 is weighed and mixed to obtain a mixed powder (or mixture). x = 0.1 to 0.9.

[0033] The mixing method is ball milling (referred to as primary mixing). Specifically, the prepared raw materials are added to deionized water and ball-milled once. After ball milling, the slurry is passed through an 80-mesh sieve and dried to obtain primary ball-milled material. Ball milling is performed in a nylon ball mill jar using deionized water or alcohol as the medium. The mass ratio of ball-milled material to zirconium balls to medium is 1:3:2. The ball milling speed can be 200–400 rpm, and the milling time can be 1–3 hours.

[0034] A small amount of water is added to the mixed powder (i.e., primary ball milling material), and it is pressed into shape. Solid-state synthesis is then carried out at 1000℃~1100℃ for 3~5 hours. The purpose is to dissolve multiple raw materials into the main crystalline phase (Mg). 0.9 Zn 0.05 Mn 0.05 TiO3-Ba 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 O3 (the reaction in this step forms a phase) is used to obtain a primary solid-phase synthetic powder.

[0035] The primary solid-phase synthesis powder is mixed with deionized water and then ball-milled a second time. After ball milling, the slurry is passed through an 80-mesh sieve and dried to obtain the secondary ball-milled material. Ball milling is performed in a nylon ball mill jar using deionized water or alcohol as the medium. The mass ratio of the ball-milled material to the zirconium balls to the medium is 1:3:2. The ball milling speed can be ~ rpm, and the milling time can be 1 to 3 hours.

[0036] Add a small amount of water to the secondary ball milling material, press it into shape, and then perform solid-phase synthesis at a temperature of 1100℃~1200℃ for 3~5 hours. The purpose is to make the remaining free oxides after the first synthesis more closely contact each other and react more fully (this step forms a phase), thus obtaining the secondary solid-phase synthesized powder.

[0037] The secondary solid-phase synthesis powder is crushed, then deionized water is added for secondary ball milling for 1-2 hours. The ball-milled slurry is then dried through an 80-mesh sieve to obtain the tertiary ball-milled material. The ball milling speed can be 200-400 rpm.

[0038] The tertiary ball milling material is mixed with 1-2% polyvinyl alcohol solution (binder) and then granulated. The granulated powder is pressed into cylinders with a diameter of 15 mm (e.g., at a pressure of 20 MPa) to obtain a green preform.

[0039] The green blank was sintered at 1200℃~1300℃ in air atmosphere for 6~10 hours to obtain a main crystalline phase of (Mg). 0.9 Zn 0.05 Mn 0.05 TiO3-Ba 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 O3-based microwave dielectric ceramic materials with high dielectric constant.

[0040] Performance testing:

[0041] In this invention, the microwave dielectric properties are measured using the Hakki-Coleman open cylindrical network dielectric resonance method. The TE011 mode is used to determine the relative permittivity εr and quality factor Q×f of the sample at the microwave frequency. The instrument used is an Agilent E8362B vector network analyzer. The test sample is a Φ12×6mm cylinder. The temperature coefficient of the resonant frequency of the sample is measured using a VT7004 oven with a test temperature range of 25~85℃.

[0042] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0043] Example 1

[0044] (1) Ingredients: MgO powder, ZnO powder, MnO2 powder, TiO2 powder, BaO powder, ZrO2 powder, SnO2 powder, and Nd2O3 powder are used as raw materials, according to the chemical formula (1-x)(Mg 0.9 Zn 0.05 Mn 0.05 TiO3-xBa 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 The ingredients (mixture) are prepared according to the molar ratio of O3, where x = 0.1; see Table 1 for the specific formula;

[0045] (2) First ball milling: Add the mixture prepared in step 1 to deionized water and mix for first ball milling. After ball milling, the slurry is passed through an 80-mesh sieve and dried to obtain the first ball milling material. Ball milling is carried out in a nylon ball milling jar. The medium is deionized water or alcohol. The ratio of the ball milling material to the zirconium balls to the medium is 1:3:2. The ball milling time is 1 to 3 hours.

[0046] (3) Solid-phase synthesis: Add a small amount of water to the primary ball milling material, press it into shape, and perform solid-phase synthesis at 1130℃ for 4 hours to obtain solid-phase synthesized powder.

[0047] (4) Secondary ball milling: The solid-phase synthetic powder is mixed with deionized water and ball milled twice. After ball milling, the slurry is passed through an 80-mesh sieve and dried to obtain the secondary ball milled material.

[0048] (5) Secondary solid-phase synthesis: Add a small amount of water to the secondary ball milling material, press it into shape, and perform solid-phase synthesis at 1150℃ for 4 hours to obtain solid-phase synthesized powder.

[0049] (6) Three-stage ball milling: The solid-phase synthetic powder is crushed, and then deionized water is added for a second ball milling. The ball milling time is 1 to 2 hours. The ball-milled slurry is dried through an 80-mesh sieve to obtain the three-stage ball-milled material.

[0050] (7) Granulation and molding: Add 1-2% polyvinyl alcohol solution to the three-stage ball milling material, mix, granulate, and then press into a cylinder with a diameter of 15 mm and a pressure of 100 MPa to obtain a green blank;

[0051] (8) Sintering; The green blank was sintered at 1200℃ in air for 4 hours to obtain a main crystalline phase of (Mg). 0.9 Zn 0.05 Mn 0.05 TiO3-Ba 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 O3-based microwave dielectric ceramic materials with high Q-value dielectric constant.

[0052] Example 2

[0053] The preparation process of the high Q value dielectric constant microwave dielectric ceramic material in Example 2 is the same as in Example 1, except that x = 0.2.

[0054] Example 3

[0055] The preparation process of the high Q value dielectric constant microwave dielectric ceramic material in Example 3 is the same as in Example 1, except that x = 0.3.

[0056] Example 4

[0057] The preparation process of the high Q value dielectric constant microwave dielectric ceramic material in Example 4 is the same as in Example 1, except that x = 0.4.

[0058] Example 5

[0059] The preparation process of the high Q value dielectric constant microwave dielectric ceramic material in Example 5 is the same as in Example 1, except that x = 0.5.

[0060] Example 6

[0061] The preparation process of the high Q value dielectric constant microwave dielectric ceramic material in Example 6 is the same as in Example 1, except that x = 0.6.

[0062] Comparative Example 1

[0063] The preparation process of the microwave dielectric ceramic material with high Q value dielectric constant in Comparative Example 1 is the same as that in Example 2, except that the first phase is MgTiO3.

[0064] Comparative Example 2

[0065] The preparation process of the high Q-value dielectric constant microwave dielectric ceramic material in Comparative Example 2 is the same as in Example 2, except that the second phase is Ba. 0.9 Nd 0.2 / 3 ZrO3.

[0066] Comparative Example 3

[0067] The preparation process of the high Q-value dielectric constant microwave dielectric ceramic material in Comparative Example 3 is the same as that in Example 2, except that the first phase is Mg. 0.9 Zn 0.1 TiO3.

[0068] Comparative Example 4

[0069] The preparation process of the high Q-value dielectric constant microwave dielectric ceramic material in Comparative Example 4 is the same as in Example 2, except that the first phase is Mg. 0.9 Mn 0.1 TiO3.

[0070] Table 1 shows the composition and microwave dielectric properties of the high Q-value microwave dielectric ceramic material in this invention:

[0071]

[0072] As shown in Table 1, the optimal solutions among Examples 1-6 are Examples 2, 3, 4, and 5. However, this invention is not limited to the above six specific embodiments.

[0073] The test results from the examples lead to the conclusion that: (Mg 0.9 Zn 0.05 Mn 0.05 TiO3 is produced by doping with fixed proportions of ZnO, MnO2, and SnO2, and adding different proportions of Ba. 0.9 Nd 0.2 / 3 Zr 0.95 Sn0.05 O3 can lower the sintering temperature of microwave dielectric ceramic materials with high dielectric constant. The higher the addition ratio, the higher the dielectric constant increases linearly, but the Q×f value decreases linearly. When the addition ratio exceeds 0.6, the Q×f value drops significantly. Therefore, the optimal addition ratio x is 0.2-0.5. At the same time, within a certain range, the frequency temperature coefficient is close to zero, which fully meets the requirements for filter use.

[0074] from Figure 1 and 2 It can be seen that the microwave dielectric material of the present invention has two main crystal phases in its grain composition, namely (Mg) 0.9 Zn 0.05 Mn 0.05 )TiO3 phase and Ba 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 The O3 phase has two crystal phases that are evenly distributed, with clear grain boundaries and uniform grain size. It has low porosity, dense material, and is suitable for mass production.

Claims

1. A low temperature sintered high Q value, high dielectric constant microwave dielectric ceramic material, characterized by, The high Q value dielectric constant microwave dielectric ceramic material has a chemical composition of (1-x)(Mg 0.9 Zn 0.05 Mn 0.05 )TiO3-xBa 0.9 Nd 0.2 / 3Zr 0.95 Sn 0.05 O3, wherein 0.2≤x≤0.

5. The high Q value dielectric constant microwave medium ceramic material has a Qxf value of 56000-77000. The high Q value dielectric constant microwave medium ceramic material has a relative dielectric constant of 19.5-30.

5. The high Q value dielectric constant microwave medium ceramic material has a resonance frequency temperature coefficient of ±11.8ppm / ℃.

2. The high Q value, medium dielectric constant microwave dielectric ceramic material according to claim 1, characterized by, The high Q value dielectric constant microwave medium ceramic material has a compactness of more than 99%.

3. The high Q, medium dielectric constant microwave dielectric ceramic material of claim 1, wherein, The high Q value dielectric constant microwave medium ceramic material is prepared by sintering at 1200-1300℃ in air atmosphere.

4. A method of producing the high Q-value, medium dielectric constant microwave dielectric ceramic material according to any one of claims 1 to 3, characterized by, Comprise: (1) MgO powder, ZnO powder, MnO2 powder, TiO2 powder, BaO powder, ZrO2 powder, SnO2 powder, and Nd2O3 powder are used as raw materials, and are weighed and mixed according to the molar ratio of (1-x)(Mg 0.9 Zn 0.05 Mn 0.05 )TiO3-xBa 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 O3, to obtain a mixed powder; (2) performing primary solid-phase synthesis and secondary solid-phase synthesis on the mixed powder to obtain raw material powder; (3) granulating the raw material powder and a binder to obtain granulated powder; (4) The granulated powder is pressed and formed, and sintered at 1200-1300 °C for 6-10 hours in air atmosphere to obtain high Q-value microwave dielectric ceramic material with main crystal phase of (Mg 0.9 Zn 0.05 Mn 0.05 )TiO3-Ba 0.9 Nd 0.2 / 3 Zr 0.95 Sn 0.05 O3.

5. The preparation method according to claim 4, characterized in that, The temperature of the primary solid-phase synthesis is 1000-1100℃, and the synthesis time is 3-5 hours.

6. The preparation method according to claim 4, characterized in that, The temperature of the secondary solid-phase synthesis is 1100-1200℃, and the temperature of the secondary solid-phase synthesis is higher than that of the primary solid-phase synthesis, and the synthesis time is 3-5 hours.

7. The preparation method according to claim 4, characterized in that, The binder is a polyvinyl alcohol solution with a concentration of 1-2wt%, and the ratio of the binder to the raw material powder is (6-10)mL:1g.

8. The preparation method according to claim 4, characterized in that, The pressure of the press forming is 80-200MPa.

9. The preparation method according to claim 8, characterized in that, The pressure of the press forming is 100MPa.

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