CN111943670A

CN111943670A - LiWVO6-K2MoO4Base composite ceramic microwave material and preparation method thereof

Info

Publication number: CN111943670A
Application number: CN202010607150.4A
Authority: CN
Inventors: 刘亚晗; 宋开新; 季玉平; 刘兵; 徐军明; 高惠芳; 武军
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2020-11-17
Anticipated expiration: 2040-06-30
Also published as: CN111943670B

Abstract

The invention discloses LiWVO₆‑K₂MoO₄The composite ceramic microwave material has chemical general expression of (1-x) LiWVO₆‑xK₂MoO₄Wherein x is mass percent (x ═ 60, 65, 70, 75, 80, 90 wt%). K₂MoO₄The ceramic has excellent microwave performance and low sintering temperature of about 540 ℃,_rabout 7.5, Qf to 22300GHz, but τ_fThe value was-70 ppm/. degree.C. Recently, a vanadate LiWVO is discovered₆The dielectric ceramic material has a monoclinic structure, and the dielectric property obtained by high-temperature sintering at 700 ℃ is as follows:_r～11.5，Qf～13260GHz，τ_f+163.8 ppm/DEG C. The invention prepares densified LiWVO at the temperature of below 200 ℃ by a cold sintering method₆‑K₂MoO₄Composite ceramic to obtain (1-x) LiWVO with near-zero resonant frequency temperature coefficient₆‑xK₂MoO₄A base composite ceramic microwave material. The composite ceramic material can be widely applied to microwave devices such as resonators, filters and the like.

Description

LiWVO6-K2MoO4Base composite ceramic microwave material and preparation method thereof

Technical Field

The invention relates to the technical field of microwave communication electronic circuit device materials and low-carbon energy-saving production, in particular to a microwave communication electronic circuit device material with LiWVO as a component₆-K₂MoO₄A base composite ceramic microwave material and a low-carbon energy-saving preparation method thereof.

Background

Microwave dielectric ceramics are widely used in modern wireless communication systems as resonators, couplers, filters, substrates and capacitors. With the rapid development of mobile communication technology in the millimeter wave direction, modern electronic communication products are revolutionarily promoted in the direction of generalization, miniaturization and high efficiency, which increases the requirements and demands on high-performance microwave materials. In particular, microwave materials that can be used in modern mobile communication devices must have three conditions, the first: has a low dielectric constant (_r) The delay of the signal is reduced, and the transmission of the signal is accelerated. Secondly, the method comprises the following steps: has a high quality factor (Qf) to obtain good filtering characteristics and communication quality. Thirdly, the method comprises the following steps: having a temperature coefficient of resonance frequency (tau) close to zero_f) The microwave device can be used for ensuring that the device prepared by the microwave device can keep stable temperature and normally work in different environments. A large number of microwave dielectric ceramics now have excellent dielectric properties, but usually have too high a sintering temperature or a temperature coefficient of resonance frequency (tau)_f) Too large a situation, which limits its application in practical production and does not comply with the green production advocated by the state. In order to overcome the problems and reduce the production energy consumption, the invention adopts a sintering process-Cold Sintering Process (CSP) composite with negative tau to synthesize compact ceramics at low temperature (less than or equal to 200 ℃) by using water as an instant solvent under uniaxial pressure_fValue K₂MoO₄And has a positive τ_fLiWVO of value₆To regulate and control the temperature coefficient and prepare the (1-x) LiWVO with the temperature coefficient close to zero₆-xK₂MoO₄。

Disclosure of Invention

The invention aims to provide LiWVO₆-K₂MoO₄The microwave material and its preparation process can prepare compact microwave material with fine and homogeneous crystal grains and relative density over 92% at 200 deg.c. The dielectric constant of the composite ceramic microwave material (C:)_r) The range is 6.8-8.5, the range of the quality factor Qf is 2050 GHz-7180 GHz, and the temperature coefficient tau of the resonant frequency_fThe range of-49.3 ppm/DEG C to +24.8 ppm/DEG C. Compared with the traditional high temperature solid phase sintering (HTCC) and low temperature co-firing (LTCC) technologies, the method has the characteristics of low sintering temperature, short sintering time, low carbon and energy saving.

In order to achieve the purpose, the invention adopts the technical scheme that:

LiWVO₆-K₂MoO₄the chemical composition of the composite ceramic microwave material can be represented by the following general formula: (1-x) LiWVO₆-xK₂MoO₄Wherein x is mass percent (x is 60, 65, 70, 75, 80, 90 wt%); its dielectric constant_rThe range is 6.8-8.5, the range of the quality factor Qf is 2050 GHz-7180 GHz, and the temperature coefficient tau of the resonant frequency_fThe range of-49.3 ppm/DEG C to +24.8 ppm/DEG C.

The invention also provides LiWVO₆-K₂MoO₄The low-carbon energy-saving preparation method of the base composite ceramic microwave material comprises the following steps:

(1) preparing materials: firstly, according to the chemical general formula LiWVO₆The following experimental raw materials are weighed according to the stoichiometric ratio of Li, W and V elements in the raw materials: li₂CO₃(99.99％)、WO₃(99.99％)、NH₄VO₃(99.99％)；

(2) Mixing materials: pouring the weighed raw materials into a ball milling tank, taking absolute ethyl alcohol as a ball milling medium, and carrying out ball milling for 4 hours in the ball milling tank to obtain mixed slurry;

(3) drying: and pouring the mixed slurry into a tray with a spread preservative film, and putting the tray into a drying box to be dried to constant weight at 80 ℃ to obtain dry powder of the mixture.

(4) Pre-burning: and (3) sieving the mixture dry powder obtained in the last step by a 60-mesh sieve, then putting the mixture dry powder into a high-temperature furnace, heating to 700 ℃ at the heating rate of 5 ℃/min, preserving heat for 6h, and then naturally cooling. The mixture is subjected to preliminary reaction to synthesize LiWVO₆A compound;

(5) secondary ball milling: the preliminarily synthesized LiWVO₆Pouring into a ball milling tank, and repeating the steps (2) and (3).

(6) Preparing materials: synthesizing LiWVO₆And K₂MoO₄(purity 99%) raw materials are weighed according to weight ratio;

(7) mixing materials: the weighed raw materials are put into a mortar, deionized water accounting for 10 wt% of the total mass of the mixture is added, and the mixture is uniformly ground. LiWVO with different weight ratios is obtained₆-K₂MoO₄Mixing the slurry;

(8) and (3) cold sintering: placing the ground aqueous mixture slurry into a mould, then placing the mould into a hot press, heating to 160 ℃, applying pressure to 300MPa, and carrying out hot pressing for 60 minutes to obtain a densified sample;

(9) and (3) drying: further drying the obtained densified composite ceramic sample in a drying oven at 120 ℃ for 24 hours to remove residual moisture to obtain LiWVO₆-K₂MoO₄And (5) preparing a composite ceramic finished product.

In the above technical scheme, the raw material for preparing the composite ceramic is lithium carbonate (LiCO)₃) Tungsten trioxide (WO)₃) Ammonium metavanadate (NH)₄VO₃) And potassium molybdate (K)₂MoO₄). The low-carbon energy-saving preparation method comprises the following steps: firstly, weighing raw materials (lithium carbonate, tungsten trioxide and silicon dioxide) according to a certain stoichiometric ratio, uniformly ball-milling, drying, presintering to synthesize LiWVO₆A compound; then the prepared LiWVO is added₆And K₂MoO₄Weighing according to a certain weight ratio; adding 10 wt% of deionized water and mixing evenly LiWVO₆And K₂MoO₄Compounding powder; placing the composite mixture into a moldHeating in a hot press at 160 deg.C under 300MPa for 60min, cooling, taking out the sample, and drying at 120 deg.C for 24 hr to obtain compact (1-x) LiWVO₆-xK₂MoO₄Composite ceramic materials. The low-temperature energy-saving preparation method can prepare LiWVO with fine and uniform crystal grains and the relative density of more than or equal to 92 percent under the low-temperature condition of less than or equal to 200 DEG C₆-K₂MoO₄A base composite ceramic. Compared with the conventional ceramic sintering (HTCC and LTCC) technology, the method can not only realize densification in a lower temperature range to obtain the composite-based microwave ceramic material with good temperature stability, but also reduce carbon emission and energy consumption in the preparation and processing process.

In the technical scheme, the LiWVO adopted by the invention₆And K₂MoO₄Both ceramic materials have a low dielectric constant and a high quality factor. The low dielectric constant can shorten the propagation delay time of signals such as electromagnetism and the like and minimize the cross coupling between conductors, and the high quality factor can reduce the energy loss of a microwave system and expand the frequency selection range of the resonator. Meanwhile, LiWVO₆Having a positive temperature coefficient of the resonance frequency, K₂MoO₄Has negative temperature coefficient of resonant frequency, and the LiWVO with the temperature coefficient of resonant frequency close to zero can be obtained by compounding the two ceramic materials₆-K₂MoO₄A base composite ceramic microwave material. And the temperature coefficient of the near-zero resonant frequency can ensure the stability of the working frequency to the temperature change. The invention adopts Cold Sintering (CSP) technology to synthesize LiWVO₆-K₂MoO₄The microwave material based on composite ceramic realizes densification at a low temperature of less than or equal to 200 ℃, has simple process, much shorter period than the traditional sintering method for preparing ceramic, less energy consumption in the preparation process and greatly reduced pollutants, and has great potential in the aspect of the manufacturing process of wireless communication technology.

The invention has the beneficial effects that:

(1) the invention adopts the cold sintering technology to synthesize LiWVO₆-K₂MoO₄The composite ceramic microwave material is prepared by mixing with conventional high temperature sintering (CS) and low temperature co-firing (L) technologiesTCC) is adopted, the preparation process is simple, the sintering temperature is only 160 ℃, the sintering time is only 1 hour, the preparation period of the ceramic is greatly shortened, and the carbon emission is reduced.

(2) The invention does not need PVA binder, takes deionized water as instantaneous liquid, mixes the powder and water and puts the mixture into a die, and then prepares LiWVO with fine and uniform crystal grains and relative density more than or equal to 92 percent by sintering₆-K₂MoO₄A base composite ceramic.

Drawings

FIG. 1 is an XRD spectrum of a composite ceramic microwave material prepared in examples 1-6 of the present invention;

FIG. 2 is an SEM image of composite ceramic microwave materials prepared in examples 1-6 of the present invention;

FIG. 3 is a drawing showing relative densities of composite ceramic microwave materials prepared in examples 1 to 6 of the present invention;

FIG. 4 is a drawing showing the dielectric constants of composite ceramic microwave materials prepared in examples 1 to 6 of the present invention;

FIG. 5 is a figure showing quality factors of composite ceramic microwave materials prepared in examples 1 to 6 of the present invention;

FIG. 6 shows the temperature coefficients of the resonant frequencies of the composite ceramic microwave materials prepared in examples 1 to 6 of the present invention.

The following specific embodiments will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

The technical solution provided by the present invention will be further explained with reference to the accompanying drawings.

The invention provides LiWVO₆-K₂MoO₄The microwave material and the low-carbon preparation method of the base composite ceramic are specifically shown in the following examples.

Example 1: preparation of 40 wt% LiWVO₆-60wt％K₂MoO₄Composite ceramic microwave material

Sequentially weighing Li₂CO₃(99.99％)4.3758g、WO₃(99.99％)27.4597g、NH₄VO₃(99.99%) 13.8547 g. Putting the weighed materials into a ball milling tank with absolute ethyl alcohol as a medium for ball millingObtaining slurry raw materials after 12 hours; and pouring the mixed slurry into a tray with a plastic wrap, and putting the tray into a drying box to be dried to constant weight to obtain mixed dry powder. Grinding the dried mixed dry material, sieving with a 60-mesh sieve, placing into a high-temperature furnace, heating to 700 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 6 hours, and then naturally cooling. The mixture is subjected to preliminary reaction to synthesize 40g LiWVO₆A compound is provided.

Then sequentially weighing the synthesized LiWVO₆Powder 0.8000g, K₂MoO₄(99%) 1.2121g of the starting material were placed in a mortar to obtain 2.0121g of LiWVO₆、K₂MoO₄Mixing the powder. And dropwise adding deionized water accounting for 10 wt% of the total mass of the mixture into the powder, and uniformly grinding to form slurry. Selecting a steel die with an inner hole diameter of 12mm, dipping the degreased cotton into absolute ethyl alcohol to clean the inner wall of the die, an ejector rod and a cushion block respectively before the die is used, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying 300MPa pressure by using a single-shaft press, heating the die to 160 ℃ at a heating rate of 6 ℃/min, preserving the temperature for 60min, cooling, demolding and taking out a sample. The obtained sample was dried in a drying oven at 120 ℃ for 24 hours to further remove the residual moisture, to obtain 40 wt% LiWVO₆-60wt％K₂MoO₄Composite ceramic microwave material. XRD analysis of the product prepared in example 1 was carried out, and as shown in FIG. 1, the XRD pattern of the product prepared in example 1 contained LiWVO₆And K₂MoO₄Two phases, and the two do not react with each other, can well react with the standard PDF card PDF #26-1205 (LiWVO) of a crystal structure database₆) And PDF #29-1021 (K)₂MoO₄) Matching, demonstrates that example 1 successfully prepares 40 wt% LiWVO₆-60wt％K₂MoO₄Composite ceramic microwave material. Scanning the SEM image of the product prepared in example 1, as shown in figure 2, the SEM image of the product prepared in example 1 shows that the sample has good crystallization, clear grain boundary, uniform grain distribution and compact microstructure. The relative density calculation was performed on the product prepared in example 1, and as shown in fig. 3, the relative density of the product prepared in example 1 was 92.7%. For instance, a pair of fruitsDielectric constant of the product prepared in example 1: (_r) Testing, as shown in FIG. 4, of the product prepared in example 1_rWas 8.5. The product prepared in example 1 was subjected to a quality factor (Qf) test, as shown in fig. 5, and the Qf of the product prepared in example 1 was 2050 GHz. The product prepared in example 1 was subjected to a temperature coefficient of resonance frequency (. tau.)_f) Test for τ of the product prepared in example 1, as shown in FIG. 6_fIs +24.8 ppm/DEG C. As can be seen from the results of the figure, the product prepared in example 1 has high relative density and good microwave dielectric property.

Example 2: preparation of 35 wt% LiWVO₆-65wt％K₂MoO₄Composite ceramic microwave material

LiWVO synthesized in example 1 was weighed in order₆Powder 0.7000g, K₂MoO₄(99%) 1.3131g of the starting material were placed in a mortar to obtain 2.0131g of LiWVO₆-K₂MoO₄Mixing the powder. And dropwise adding deionized water accounting for 10 wt% of the mixed powder into the powder, and uniformly grinding to form slurry. Selecting a steel die with an inner hole diameter of 12mm, dipping the degreased cotton into absolute ethyl alcohol to clean the inner wall of the die, an ejector rod and a cushion block respectively before the die is used, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying 300MPa pressure by using a single-shaft press, heating the die to 160 ℃ at a heating rate of 6 ℃/min, preserving the temperature for 60min, cooling, demolding and taking out a sample. The obtained sample was dried in a drying oven at 120 ℃ for 24 hours to further remove the residual moisture, to obtain 35 wt% LiWVO₆-65wt％K₂MoO₄Composite ceramic microwave material. XRD analysis of the product prepared in example 2 was carried out, and as shown in FIG. 1, the XRD pattern of the product prepared in example 2 comprised LiWVO₆And K₂MoO₄Two phases, and the two do not react with each other, can well react with the standard PDF card PDF #26-1205 (LiWVO) of a crystal structure database₆) And PDF #29-1021 (K)₂MoO₄) Matching, illustrates example 2 successful preparation of 20 wt% LiWVO₆-80wt％K₂MoO₄Composite ceramic microwave material. SEM image scanning of the product prepared in example 2 is shown in figure 2, which is an example2, the SEM atlas of the product prepared shows that the sample has good crystallization, clear crystal boundary, even grain distribution, grown grains and compact microstructure. The relative density calculation was performed on the product prepared in example 2, and as shown in fig. 3, the relative density of the product prepared in example 2 was 94.6%. The product prepared in example 2 was subjected to dielectric constant: (_r) Testing, as shown in FIG. 4, of the product prepared in example 2_rIt was 8.2. The product prepared in example 2 was subjected to a quality factor (Qf) test, as shown in fig. 5, and the Qf of the product prepared in example 2 was 3260 GHz. The product prepared in example 2 was subjected to a temperature coefficient of resonance frequency (. tau.)_f) τ of the product prepared in example 2 was tested, as shown in FIG. 6_fIs +9.9 ppm/DEG C. As can be seen from the results of the figure, the product prepared in example 2 has high relative density and good microwave dielectric property.

Example 3: preparation of 30 wt% LiWVO₆-70wt％K₂MoO₄Composite ceramic microwave material

LiWVO synthesized in example 1 was weighed in order₆Powder 0.6000g, K₂MoO₄(99%) 1.3131g of the starting material was placed in a mortar to obtain 2.0141g of LiWVO₆-K₂MoO₄Mixing the powder. And dropwise adding deionized water accounting for 10 wt% of the mixed powder into the powder, and uniformly grinding to form slurry. Selecting a steel die with an inner hole diameter of 12mm, dipping the degreased cotton into absolute ethyl alcohol to clean the inner wall of the die, an ejector rod and a cushion block respectively before the die is used, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying 300MPa pressure by using a single-shaft press, heating the die to 160 ℃ at a heating rate of 6 ℃/min, preserving the temperature for 60min, cooling, demolding and taking out a sample. The obtained sample was dried in a drying oven at 120 ℃ for 24 hours to further remove the residual moisture, to obtain 30 wt% LiWVO₆-70wt％K₂MoO₄Composite ceramic microwave material. XRD analysis of the product prepared in example 3 was carried out, and as shown in FIG. 1, the XRD pattern of the product prepared in example 3 comprised LiWVO₆And K₂MoO₄Two phases, and no mutual reaction between the two phases, can be well matched with the crystal structureStandard PDF card PDF #26-1205 of database (LiWVO)₆) And PDF #29-1021 (K)₂MoO₄) Matching, demonstrates example 3 successfully preparing 30 wt% LiWVO₆-70wt％K₂MoO₄Composite ceramic microwave material. Scanning the SEM image of the product prepared in example 3 shows that the sample is well crystallized, the grain size is reduced, the grain boundary is clear, the gaps between the grains are reduced, and the distribution of the grains is compact as shown in figure 2. The relative density calculation was performed on the product prepared in example 3, and as shown in fig. 3, the relative density of the product prepared in example 3 was 95.3%. Dielectric constant of the product prepared in example 3: (_r) Testing, as shown in FIG. 4, of the product prepared in example 3_rIt was 7.8. The product prepared in example 3 was subjected to a quality factor (Qf) test, as shown in fig. 5, and the Qf of the product prepared in example 3 was 4510 GHz. The product prepared in example 3 was subjected to a temperature coefficient of resonance frequency (. tau.)_f) τ of the product prepared in example 3 was tested, as shown in FIG. 5_fIs +1.3 ppm/DEG C. As can be seen from the results of the figure, the product prepared in example 3 has high relative density and good microwave dielectric property.

Example 4: preparation of 25 wt% LiWVO₆-75wt％K₂MoO₄Composite ceramic microwave material

LiWVO synthesized in example 1 was weighed in order₆Powder 0.5000g, K₂MoO₄(99%) 1.5151g of the starting material were placed in a mortar to obtain 2.0151g of LiWVO₆-K₂MoO₄Mixing the powder. And dropwise adding deionized water accounting for 10 wt% of the mixed powder into the powder, and uniformly grinding to form slurry. Selecting a steel die with an inner hole diameter of 12mm, dipping the degreased cotton into absolute ethyl alcohol to clean the inner wall of the die, an ejector rod and a cushion block respectively before the die is used, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying 300MPa pressure by using a single-shaft press, heating the die to 160 ℃ at a heating rate of 6 ℃/min, preserving the temperature for 60min, cooling, demolding and taking out a sample. The obtained sample was dried in a drying oven at 120 ℃ for 24 hours to further remove the residual moisture, to obtain 25 wt% LiWVO₆-75wt％K₂MoO₄Composite ceramic microwave material. XRD analysis of the product prepared in example 4 was carried out as shown in figure 1, with the XRD pattern of the product prepared in example 4 comprising LiWVO₆And K₂MoO₄Two phases, and the two do not react with each other, can well react with the standard PDF card PDF #26-1205 (LiWVO) of a crystal structure database₆) And PDF #29-1021 (K)₂MoO₄) Matching, demonstrates example 4 successfully preparing 40 wt% LiWVO₆-60wt％K₂MoO₄Composite ceramic microwave material. Scanning the SEM image of the product prepared in the example 4, as shown in the attached figure 2, the SEM image of the product prepared in the example 4 shows that the sample is well crystallized, the grain size is smaller than that of the product prepared in the example 1, the grain boundary is clear, the gaps among the grains are reduced, and the distribution of the grains is compact. The relative density calculation was performed on the product prepared in example 4, as shown in fig. 3, and the relative density of the product prepared in example 4 was 96.6%. Dielectric constant of the product prepared in example 4: (_r) Testing, as shown in FIG. 4, of the product prepared in example 4_rIt was 7.6. The product prepared in example 4 was subjected to a quality factor (Qf) test, as shown in fig. 4, and the Qf of the product prepared in example 4 was 5315 GHz. The product prepared in example 4 was subjected to a temperature coefficient of resonance frequency (. tau.)_f) τ of the product prepared in example 4 was tested, as shown in FIG. 6_fAt-12.7 ppm/deg.C. As can be seen from the results of the figure, the product prepared in example 4 has high relative density and good microwave dielectric property.

Example 5: preparation of 20 wt% LiWVO₆-80wt％K₂MoO₄Composite ceramic microwave material

LiWVO synthesized in example 1 was weighed in order₆Powder 0.4000g, K₂MoO₄(99%) 1.6161g of the starting material were placed in a mortar to obtain 2.0161g of LiWVO₆-K₂MoO₄Mixing the powder. And dropwise adding deionized water accounting for 10 wt% of the mixed powder into the powder, and uniformly grinding to form slurry. Selecting a steel mould with an inner hole diameter of 12mm, dipping the degreased cotton into absolute ethyl alcohol to clean the inner wall of the mould, the ejector rod and the cushion block respectively before the mould is used, and drying the mouldWeighing a proper amount of slurry, putting the slurry into a mold, applying 300MPa pressure by using a single-shaft press, heating the mold to 160 ℃ at the heating rate of 6 ℃/min, preserving heat for 60min, cooling, demolding and taking out a sample. The obtained sample was dried in a drying oven at 120 ℃ for 24 hours to further remove the residual moisture, to obtain 20 wt% LiWVO₆-80wt％K₂MoO₄Composite ceramic microwave material. XRD analysis of the product prepared in example 5 was carried out, and as shown in FIG. 1, the XRD pattern of the product prepared in example 5 comprised LiWVO₆And K₂MoO₄Two phases, and no mutual reaction between the two phases, can well react with the standard crystal structure database PDF card PDF #26-1205 (LiWVO)₆) And PDF #29-1021 (K)₂MoO₄) Matching, indicating that example 5 successfully produced 50 wt% LiWVO₆-50wt％K₂MoO₄Composite ceramic microwave material. SEM image scanning of the product prepared in example 5, as shown in figure 2, the SEM image of the product prepared in example 5 showed that the sample crystallized well due to K₂MoO₄The crystal grain is smaller with K₂MoO₄The increase of the mass fraction reduces the grain size, the grain boundaries of the grains are clear, the gaps among the grains are reduced, the distribution of the grains is compact, and a compact microstructure is shown. The relative density calculation was performed on the product prepared in example 5, as shown in fig. 3, and the relative density of the product prepared in example 5 was 98.5%. The product prepared in example 5 was subjected to dielectric constant: (_r) Testing, as shown in FIG. 4, of the product prepared in example 5_rIt was 7.3. The product prepared in example 5 was subjected to a quality factor (Qf) test, as shown in fig. 5, and the Qf of the product prepared in example 5 was 5965 GHz. The product prepared in example 5 was subjected to a temperature coefficient of resonance frequency (. tau.)_f) τ of the product prepared in example 5 was tested, as shown in FIG. 6_fAt-20.1 ppm/deg.C. As can be seen from the results of the figure, the product prepared in example 5 has high relative density and good microwave dielectric property.

Example 6: preparation of 10 wt% LiWVO₆-90wt％K₂MoO₄Composite ceramic microwave material

LiWVO synthesized in example 1 was weighed in order₆Powder 0.1000g, K₂MoO₄(99%) 1.8181g of the starting material were placed in a mortar to obtain 2.0181g of LiWVO₆-K₂MoO₄Mixing the powder. And dropwise adding deionized water accounting for 10 wt% of the mixed powder into the powder, and uniformly grinding to form slurry. Selecting a steel die with an inner hole diameter of 12mm, dipping the degreased cotton into absolute ethyl alcohol to clean the inner wall of the die, an ejector rod and a cushion block respectively before the die is used, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying 300MPa pressure by using a single-shaft press, heating the die to 160 ℃ at a heating rate of 6 ℃/min, preserving the temperature for 60min, cooling, demolding and taking out a sample. The obtained sample was dried in a drying oven at 120 ℃ for 24 hours to further remove the residual moisture, to obtain 10 wt% LiWVO₆-90wt％K₂MoO₄Composite ceramic microwave material. XRD analysis of the product prepared in example 6 was carried out, and as shown in FIG. 1, the XRD pattern of the product prepared in example 6 contained LiWVO₆And K₂MoO₄Two phases, and no mutual reaction between the two phases, can well react with the standard crystal structure database PDF card PDF #26-1205 (LiWVO)₆) And PDF #29-1021 (K)₂MoO₄) Matching, indicating that example 6 successfully produced 60 wt% LiWVO₆-40wt％K₂MoO₄Composite ceramic microwave material. Scanning the SEM image of the product prepared in example 6, as shown in figure 2, the SEM image of the product prepared in example 6 shows that the sample is well crystallized, the grain boundaries are clear, the gaps among the grains are few, the distribution of the grains is compact, and a compact microstructure is shown. The relative density calculation was performed on the product prepared in example 6, as shown in fig. 3, and the relative density of the product prepared in example 6 was 98.7%. Dielectric constant of the product prepared in example 6: (_r) Testing, as shown in FIG. 3, of the product prepared in example 6_rIt was 6.8. The product prepared in example 6 was subjected to a quality factor (Qf) test, as shown in fig. 5, and the Qf of the product prepared in example 6 was 7180 GHz. The product prepared in example 6 was subjected to a temperature coefficient of resonance frequency (. tau.)_f) τ of the product prepared in example 6 was measured, as shown in FIG. 6_fIs-49.3 ppm/DEG C. As can be seen from the results of the figure, the product prepared in example 6 has high relative density and good microwave dielectric properties.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1.LiWVO₆-K₂MoO₄The base composite ceramic microwave material is characterized in that: the general formula of the chemical composition of the composite ceramic microwave material is as follows: (1-x) LiWVO₆-xK₂MoO₄X is mass percent; dielectric constant of the composite ceramic microwave material_rThe range is 6.8-8.5, the range of the quality factor Qf is 2050 GHz-7180 GHz, and the temperature coefficient tau of the resonant frequency_fThe range of-49.3 ppm/DEG C to +24.8 ppm/DEG C.

2. The LiWVO of claim₆-K₂MoO₄The base composite ceramic microwave material is characterized in that: x is 60, 65, 70, 75, 80 or 90 wt%.

3.LiWVO₆-K₂MoO₄The low-carbon preparation method of the base composite ceramic microwave material is characterized by comprising the following steps of:

(1) preparing materials: first, pressingGeneral formula LiWVO₆The following experimental raw materials are weighed according to the stoichiometric ratio of Li, W and V elements in the raw materials: li₂CO₃、WO₃、NH₄VO₃；

(2) Mixing materials: pouring the weighed raw materials into a ball milling tank, taking absolute ethyl alcohol as a ball milling medium, and performing ball milling in the ball milling tank to obtain mixed slurry;

(3) drying: pouring the mixed slurry into a tray with a spread preservative film, and putting the tray into a drying box to be dried to constant weight at 80 ℃ to obtain dry powder of the mixture;

(4) pre-burning: sieving the mixture dry powder obtained in the last step by a 60-mesh sieve, then putting the mixture dry powder into a high-temperature furnace, heating to 700 ℃ at the heating rate of 5 ℃/min, preserving heat for 6h, and then naturally cooling; the mixture is subjected to preliminary reaction to synthesize LiWVO₆A compound;

(5) secondary ball milling: the preliminarily synthesized LiWVO₆Pouring into a ball milling tank, and repeating the steps (2) and (3);

(6) preparing materials: synthesizing LiWVO₆And K₂MoO₄Weighing the raw materials according to the weight ratio;

(7) mixing materials: putting the weighed raw materials into a mortar, adding deionized water accounting for 10 wt% of the total mass of the mixture, and uniformly grinding; LiWVO with different weight ratios is obtained₆-K₂MoO₄Mixture paste, i.e., (1-x) LiWVO₆-xK₂MoO₄X is mass percent;

4. LiWVO of claim 3₆-K₂MoO₄The low-carbon preparation method of the base composite ceramic microwave material is characterized in that，Li₂CO₃Is at least 99.99%.

5. LiWVO of claim 3₆-K₂MoO₄The low-carbon preparation method of the base composite ceramic microwave material is characterized in that WO₃Is at least 99.99%.

6. LiWVO of claim 3₆-K₂MoO₄The low-carbon preparation method of the base composite ceramic microwave material is characterized in that NH₄VO₃Is at least 99.99%.

7. LiWVO of claim 3₆-K₂MoO₄The low-carbon preparation method of the base composite ceramic microwave material is characterized in that K₂MoO₄Is at least 99%.

8. LiWVO of claim 3₆-K₂MoO₄The low-carbon preparation method of the base composite ceramic microwave material is characterized in that x is 60, 65, 70, 75, 80 or 90 wt%.

9. LiWVO of claim 3₆-K₂MoO₄The low-carbon preparation method of the base composite ceramic microwave material is characterized in that the dielectric constant of the prepared composite ceramic microwave material_rThe range is 6.8-8.5, the range of the quality factor Qf is 2050 GHz-7180 GHz, and the temperature coefficient tau of the resonant frequency_fThe range of-49.3 ppm/DEG C to +24.8 ppm/DEG C.