阅读说明：本技术 一种铈酸锶系中介电常数微波介质陶瓷材料及其制备方法 (Strontium cerate-based microwave dielectric ceramic material with medium dielectric constant and preparation method thereof ) 是由 张启龙 王浩 杨辉 于 2021-08-17 设计创作，主要内容包括：本发明涉及材料科学领域,旨在提供一种铈酸锶系中介电常数微波介质陶瓷材料及其制备方法。该微波介质陶瓷材料的化学表达式为：(100-x)wt％Sr-(2)CeO-(4)+x wt％M+y wt％N；其中,M为TiO-(2)、CaTiO-(3)或Sr-(2)TiO-(4)中的一种或几种混合,N为Li-(2)CO-(3)、Bi-(2)O-(3)或ZnO中的一种或几种混合,y为N占Sr-(2)CeO-(4)和M总质量的质量分数,其中10≤x≤20,1≤y≤5。相对于铈酸锶Sr-(2)CeO-(4)微波介质陶瓷而言,本发明在保持其极高Q×f值和中介电常数性能的同时,大大降低了烧结温度,并使谐振频率温度系数保持稳定,因而能够满足谐振器、滤波器、GPS天线等微波元器件对中介电常数微波介质陶瓷材料的需求。本发明制备工艺简单,烧结温度低,可重复性好。(The invention relates to the field of material science, and aims to provide a strontium cerate-based microwave dielectric ceramic material with a medium dielectric constant and a preparation method thereof. The chemical expression of the microwave dielectric ceramic material is as follows: (100-x) wt% Sr 2 CeO 4 + x wt% M + y wt% N; wherein M is TiO 2 、CaTiO 3 Or Sr 2 TiO 4 One or more of them are mixed, N is Li 2 CO 3 、Bi 2 O 3 Or one or more of ZnO, y is N in Sr 2 CeO 4 And mass fraction of the total mass of M, wherein x is more than or equal to 10 and less than or equal to 20, and y is more than or equal to 1 and less than or equal to 5. Strontium cerate Sr 2 CeO 4 As for microwave dielectric ceramics, the invention greatly reduces the sintering temperature and keeps the temperature coefficient of the resonant frequency stable while keeping the performance of extremely high Q multiplied by f value and medium dielectric constant, thereby being capable of meeting the requirements of microwave components such as resonators, filters, GPS antennas and the likeThe requirement for microwave dielectric ceramic material with medium dielectric constant. The invention has simple preparation process, low sintering temperature and good repeatability.)

1. A strontium cerate-based microwave dielectric ceramic material with medium dielectric constant is characterized in that the chemical expression of the microwave dielectric ceramic material is as follows: (100-x) wt% Sr₂CeO₄+ x wt% M + y wt% N; wherein M is TiO₂、CaTiO₃Or Sr₂TiO₄One or more of them are mixed, N is Li₂CO₃、Bi₂O₃Or one or more of ZnO, y is N in Sr₂CeO₄And mass fraction of the total mass of M, wherein x is more than or equal to 10 and less than or equal to 20, and y is more than or equal to 1 and less than or equal to 5.

2. A method for preparing a microwave dielectric ceramic material as claimed in claim 1, characterized by comprising the steps of:

(1) according to Sr₂CeO₄The raw material SrCO is weighed according to the molar ratio of the elements₃And CeO₂Powder is subjected to ball milling and mixing for 4 hours; pre-burning for 4h at 1150 ℃, and performing secondary ball milling to obtain Sr₂CeO₄Ceramic powder;

(2) according to Sr₂CeO₄The mass ratio of M to M is (100-x), x is to weigh M which is TiO₂、CaTiO₃Or Sr₂TiO₄X is more than or equal to 10 and less than or equal to 20; according to N and Sr₂CeO₄And the ratio y of the total mass of M: 100 weighing N, N is Li₂CO₃、Bi₂O₃Or one or more of ZnO is mixed, and y is more than or equal to 1 and less than or equal to 5; sr is₂CeO₄Carrying out ball milling and mixing on the ceramic powder, the M powder and the N powder, and drying to obtain ceramic mixed powder;

(3) adding a polyvinyl alcohol solution into the ceramic mixed powder prepared in the step (2), and uniformly mixing; pressing under 150MPa to prepare a cylindrical blank;

(4) and (4) sintering the blank obtained in the step (3) for 4 hours at the temperature of 800-950 ℃ to obtain the strontium cerate-based microwave dielectric ceramic material with medium dielectric constant.

3. The method of claim 2, wherein in the step (1), the ball milling is performed by using ethanol as a ball milling medium.

4. The method according to claim 2, wherein in the step (2), the ball milling time is 4h, and the drying temperature is 80 ℃.

5. The method according to claim 2, wherein in the step (3), the polyvinyl alcohol solution is added in an amount of 10% by mass and the polyvinyl alcohol is added in an amount of 8% by mass based on the ceramic mixed powder.

6. The method according to claim 2, wherein in the step (3), the cylindrical billet has a diameter of 12.4mm and a height of 6.2 mm.

7. The method according to claim 2, wherein in the step (4), the temperature increase rate at the time of sintering is controlled to be 5 ℃/min.

Technical Field

The invention belongs to the field of material science, and particularly relates to a microwave dielectric ceramic material with a medium dielectric constant and a preparation method thereof.

Background

The microwave dielectric ceramic is a ceramic material which is applied to a microwave frequency band and plays the functions of dielectric isolation, dielectric waveguide, dielectric resonance and the like. In recent years, with the rapid development of 5G mobile communication, satellite communication, wireless network and other technologies, microwave devices are being miniaturized and high-frequency, and resonators, filters, dielectric antennas and the like made of microwave dielectric ceramic materials have become core components of communication equipment. This puts higher demands on microwave dielectric ceramic materials, such as the serialization of dielectric constants, high Q × f value, stable frequency temperature coefficient, and the like.

Strontium cerate Sr₂CeO₄The microwave dielectric ceramic has extremely high Q multiplied by f value and medium dielectric constant, shows great application prospect in the field of microwave dielectric ceramic, and draws wide attention. But its higher sintering temperature and poor temperature coefficient of resonant frequency limit its further applications.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects of the existing material system and technology and provides a medium-dielectric-constant microwave dielectric ceramic material with low sintering temperature and stable temperature coefficient of resonant frequency and a preparation method thereof.

In order to solve the technical problem, the solution provided by the invention is as follows:

provides a strontium cerate system microwave dielectric ceramic material with medium dielectric constant, the chemical expression of the microwave dielectric ceramic material is as follows: (100-x) wt% Sr₂CeO₄+ x wt% M + y wt% N; wherein M is TiO₂、CaTiO₃Or Sr₂TiO₄One or more of them are mixed, N is Li₂CO₃、Bi₂O₃Or one or more of ZnO, y is N in Sr₂CeO₄And mass fraction of the total mass of M, wherein x is more than or equal to 10 and less than or equal to 20, and y is more than or equal to 1 and less than or equal to 5.

The invention further provides a preparation method of the microwave dielectric ceramic material, which comprises the following steps:

(1) according to Sr₂CeO₄The raw material SrCO is weighed according to the molar ratio of the elements₃And CeO₂Powder is subjected to ball milling and mixing for 4 hours; pre-burning for 4h at 1150 ℃, and performing secondary ball milling to obtain Sr₂CeO₄Ceramic powder;

(2) according to Sr₂CeO₄The mass ratio of M to M is (100-x), x is to weigh M which is TiO₂、CaTiO₃Or Sr₂TiO₄X is more than or equal to 10 and less than or equal to 20; according to N and Sr₂CeO₄And the ratio y of the total mass of M: 100 weighing N, N is Li₂CO₃、Bi₂O₃Or one or more of ZnO is mixed, and y is more than or equal to 1 and less than or equal to 5; sr is₂CeO₄Carrying out ball milling and mixing on the ceramic powder, the M powder and the N powder, and drying to obtain ceramic mixed powder;

(3) adding a polyvinyl alcohol solution into the ceramic mixed powder prepared in the step (2), and uniformly mixing; pressing under 150MPa to prepare a cylindrical blank; polyvinyl alcohol is added to maintain the strength of the ceramic body by making the ceramic particles cohered.

(4) And (4) sintering the blank obtained in the step (3) for 4 hours at the temperature of 800-950 ℃ to obtain the strontium cerate-based microwave dielectric ceramic material with medium dielectric constant.

Preferably, in the step (1), ethanol is used as a ball milling medium for ball milling mixing.

Preferably, in the step (2), the ball milling time is 4h, and the drying temperature is 80 ℃.

Preferably, in the step (3), the mass fraction of the polyvinyl alcohol solution is 10%, and the adding amount is controlled so that the polyvinyl alcohol accounts for 8% of the mass of the ceramic mixed powder.

Preferably, in the step (3), the diameter of the cylindrical billet is 12.4mm, and the height of the cylindrical billet is 6.2 mm.

Preferably, in the step (4), the temperature increase rate during sintering is controlled to be 5 ℃/min.

Description of the inventive principles:

Sr₂CeO₄has a negative temperature coefficient (-62 ppm/DEG C) of the resonance frequency, which can cause the problem that the carrier signal drifts along with the temperature in practical application, thereby influencing the use performance of the device. TiO with positive resonant frequency temperature coefficient₂、CaTiO₃Or Sr₂TiO₄The negative resonance frequency temperature coefficient of the ceramic can be adjusted; li₂CO₃、Bi₂O₃Or low melting point sintered body such as ZnOThe addition of the bonding assistant can reduce the sintering temperature of the composite microwave dielectric ceramic material. The invention adopts the compound addition of the two types of ceramics to successfully maintain the original ceramic system Sr₂CeO₄The dielectric constant and the Qxf value core performance are excellent, the sintering temperature and the temperature coefficient of the resonant frequency are effectively improved, and the adoption of the compound auxiliary agent has great application prospect in the field of microwave dielectric ceramics.

Compared with the prior art, the invention has the beneficial effects that:

1. the microwave dielectric ceramic with the medium dielectric constant obtained by the invention has the dielectric constant of 18-27, the Qxf value of 28000-58500 GHz and the temperature coefficient of resonance frequency of tau being more than or equal to minus 10_fNot more than +5 ppm/DEG C, has the characteristics of medium dielectric constant, higher Q multiplied by f value, stable temperature coefficient of resonance frequency and the like;

strontium cerate Sr₂CeO₄As for the higher sintering temperature (about 1450 ℃) and the poorer temperature coefficient of the resonant frequency (about 62 ppm/DEG C) of the microwave dielectric ceramic, the invention greatly reduces the sintering temperature (from 1450 ℃ to 800-_fNot more than +5 ppm/DEG C), thereby meeting the requirements of microwave components such as resonators, filters, GPS antennas and the like on medium dielectric constant microwave dielectric ceramic materials.

2. The invention has simple preparation process, low sintering temperature and good repeatability.

Detailed Description

The following examples are presented to enable those skilled in the art to more fully understand the present invention and are not intended to limit the invention in any way.

Example 1:

the preparation method of the microwave dielectric ceramic material with medium dielectric constant in this embodiment comprises the following steps:

step (1): according to Sr₂CeO₄The raw material SrCO is weighed according to the molar ratio of the elements₃And CeO₂Powder is mixed by ball milling for 4 hours by taking ethanol as a medium; presintering at 1150 deg.C for 4 hr, and performing secondary sinteringObtaining Sr by secondary ball milling₂CeO₄Ceramic powder;

step (2): according to Sr₂CeO₄With CaTiO₃Weighing CaTiO in a mass ratio of 90:10₃According to Li₂CO₃And Sr₂CeO₄And CaTiO₃Ratio of total mass 1: 100 weigh Li₂CO₃(ii) a Sr is₂CeO₄Ceramic powder, CaTiO₃And Li₂CO₃Ball milling and mixing the powder for 4 hours, and then drying at 80 ℃;

and (3): adding the mixed powder prepared in the step (2) into a polyvinyl alcohol solution with the mass fraction of 10% to be uniformly mixed, and controlling the mass percentage of polyvinyl alcohol in the ceramic powder to be 8%; pressing under 150MPa to prepare a cylindrical blank with the diameter of 12.4mm and the height of 6.2 mm;

and (4): and (4) sintering the blank obtained in the step (3) at 800 ℃ for 4h, and controlling the temperature rise rate in the sintering process to be 5 ℃/min to prepare the strontium cerate microwave dielectric ceramic material with the medium dielectric constant.

The medium-temperature sintered low-dielectric microwave dielectric ceramic material prepared according to the formula and the steps has the following performance indexes: dielectric constant ε_r18, quality factor Q × f 28000GHz, temperature coefficient of resonance frequency τ_f＝-10ppm/℃。

Example 2:

the preparation method of the microwave dielectric ceramic material with medium dielectric constant in this embodiment comprises the following steps:

step (1): according to Sr₂CeO₄The raw material SrCO is weighed according to the molar ratio of the elements₃And CeO₂Powder is mixed by ball milling for 4 hours by taking ethanol as a medium; pre-burning for 4h at 1150 ℃, and performing secondary ball milling to obtain Sr₂CeO₄Ceramic powder;

step (2): according to Sr₂CeO₄With TiO₂Weighing TiO with the mass ratio of 80:20₂According to Bi₂O₃And Sr₂CeO₄And TiO₂The proportion of the total mass is 5: 100 weigh Bi₂O₃(ii) a Sr is₂CeO₄Ceramic powder, TiO₂And Bi₂O₃Ball milling and mixing the powder for 4 hours, and then drying at 80 ℃;

and (3): adding the mixed powder prepared in the step (2) into a polyvinyl alcohol solution with the mass fraction of 10% to be uniformly mixed, and controlling the mass percentage of polyvinyl alcohol in the ceramic powder to be 8%; pressing under 150MPa to prepare a cylindrical blank with the diameter of 12.4mm and the height of 6.2 mm;

and (4): and (4) sintering the blank obtained in the step (3) at 950 ℃ for 4h, and controlling the temperature rise rate in the sintering process to be 5 ℃/min to prepare the strontium cerate microwave dielectric ceramic material with the medium dielectric constant.

The medium-temperature sintered low-dielectric microwave dielectric ceramic material prepared according to the formula and the steps has the following performance indexes: dielectric constant ε_r27, quality factor Q × f 58500GHz, temperature coefficient of resonance frequency τ_f＝+5ppm/℃。

Example 3:

the preparation method of the microwave dielectric ceramic material with medium dielectric constant in this embodiment comprises the following steps:

step (1): according to Sr₂CeO₄The raw material SrCO is weighed according to the molar ratio of the elements₃And CeO₂Powder is mixed by ball milling for 4 hours by taking ethanol as a medium; pre-burning for 4h at 1150 ℃, and performing secondary ball milling to obtain Sr₂CeO₄Ceramic powder;

step (2): according to Sr₂CeO₄And Sr₂TiO₄The weight ratio of Sr is 85:15₂TiO₄According to ZnO and Sr₂CeO₄And Sr₂TiO₄Ratio of total mass 3: 100 weighing ZnO; sr is₂CeO₄Ceramic powder material, Sr₂TiO₄Ball-milling and mixing the ZnO powder and the ZnO powder for 4 hours, and then drying at 80 ℃;

and (3): adding the mixed powder prepared in the step (2) into a polyvinyl alcohol solution with the mass fraction of 10% to be uniformly mixed, and controlling the mass percentage of polyvinyl alcohol in the ceramic powder to be 8%; pressing under 150MPa to prepare a cylindrical blank with the diameter of 12.4mm and the height of 6.2 mm;

and (4): and (4) sintering the blank obtained in the step (3) at 930 ℃ for 4h, and controlling the temperature rise rate in the sintering process to be 5 ℃/min to prepare the strontium cerate microwave dielectric ceramic material with the medium dielectric constant.

The medium-temperature sintered low-dielectric microwave dielectric ceramic material prepared according to the formula and the steps has the following performance indexes: dielectric constant ε_r25, quality factor Qxf 53000GHz, temperature coefficient of resonance frequency tau_f＝+1.2ppm/℃。

Example 4:

the preparation method of the microwave dielectric ceramic material with medium dielectric constant in this embodiment comprises the following steps:

step (1): according to Sr₂CeO₄The raw material SrCO is weighed according to the molar ratio of the elements₃And CeO₂Powder is mixed by ball milling for 4 hours by taking ethanol as a medium; pre-burning for 4h at 1150 ℃, and performing secondary ball milling to obtain Sr₂CeO₄Ceramic powder;

step (2): according to Sr₂CeO₄And Sr₂TiO₄-TiO₂Weighing Sr at a mass ratio of 83:17₂TiO₄And TiO₂Wherein Sr is₂TiO₄And TiO₂The mass ratio of (A) to (B) is 2: 1; according to Li₂CO₃-Bi₂O₃Ratio to the total mass of the aforementioned powders 4: 100 weigh Li₂CO₃And Bi₂O₃Wherein Li₂CO₃And Bi₂O₃The mass ratio of (A) to (B) is 4: 1; ball-milling and mixing all the powder for 4 hours, and then drying at 80 ℃;

and (3): adding the mixed powder prepared in the step (2) into a polyvinyl alcohol solution with the mass fraction of 10% to be uniformly mixed, and controlling the mass percentage of polyvinyl alcohol in the ceramic powder to be 8%; pressing under 150MPa to prepare a cylindrical blank with the diameter of 12.4mm and the height of 6.2 mm;

and (4): and (4) sintering the blank obtained in the step (3) at 920 ℃ for 4h, and controlling the temperature rise rate in the sintering process to be 5 ℃/min to prepare the strontium cerate microwave dielectric ceramic material with the medium dielectric constant.

The medium-temperature sintered low-dielectric microwave dielectric ceramic material prepared according to the formula and the steps has the following performance indexes: dielectric constant ε_r24.6, quality factor Qxf 46000GHz, temperature coefficient of resonance frequency tau_f＝-3.6ppm/℃。

Example 5:

the preparation method of the microwave dielectric ceramic material with medium dielectric constant in this embodiment comprises the following steps:

step (1): according to Sr₂CeO₄The raw material SrCO is weighed according to the molar ratio of the elements₃And CeO₂Powder is mixed by ball milling for 4 hours by taking ethanol as a medium; pre-burning for 4h at 1150 ℃, and performing secondary ball milling to obtain Sr₂CeO₄Ceramic powder;

step (2): according to Sr₂CeO₄And Sr₂TiO₄-CaTiO₃The weight ratio of Sr is 80:20₂TiO₄And CaTiO₃Wherein Sr is₂TiO₄And CaTiO₃The mass ratio of (1): 2; according to ZnO-Bi₂O₃Ratio to the total mass of the aforementioned powders 3: 100 portions of ZnO and Bi₂O₃Wherein ZnO and Bi₂O₃The mass ratio of (A) to (B) is 3: 2; ball-milling and mixing all the powder for 4 hours, and then drying at 80 ℃;

and (3): adding the mixed powder prepared in the step (2) into a polyvinyl alcohol solution with the mass fraction of 10% to be uniformly mixed, and controlling the mass percentage of polyvinyl alcohol in the ceramic powder to be 8%; pressing under 150MPa to prepare a cylindrical blank with the diameter of 12.4mm and the height of 6.2 mm;

and (4): and (4) sintering the green body obtained in the step (3) at 870 ℃ for 4h, and controlling the temperature rise rate in the sintering process to be 5 ℃/min to prepare the strontium cerate microwave dielectric ceramic material with the medium dielectric constant.

The medium-temperature sintered low-dielectric microwave dielectric ceramic material prepared according to the formula and the steps has the following performance indexes: dielectric constant ε_r21.5, quality factor Q × f 32000GHz, resonant frequency temperature coefficient τ_f＝+0.6ppm/℃。