CN111499372A

CN111499372A - Low-temperature energy-saving preparation of L iMgPO4Method for microwave ceramic material

Info

Publication number: CN111499372A
Application number: CN202010262068.2A
Authority: CN
Inventors: 陈金荣; 宋开新; 刘兵; 徐军明; 高惠芳; 武军
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2020-04-06
Filing date: 2020-04-06
Publication date: 2020-08-07

Abstract

The invention discloses a low-temperature energy-saving preparation method of L iMgPO₄Method of microwave ceramic material L iMgPO₄Mixing with water or acetic acid not higher than 20 wt% to form a solid-liquid mixture, compacting by hot pressing at 150 deg.C, 200 deg.C, 250 deg.C or 300 deg.C, 30min, 60min or 90min, and applying pressure (P) to obtain L iMgPO₄Ceramic having a dielectric constant of_r) The range is 5.1 to 6.5, the range of the quality factor Q × f is 3,600GHz to 16,000GHz, and the range of the temperature coefficient of resonance frequency (TCF) is-46.1 ppm/DEG C to-59.5 ppm/DEG C, the L iMgPO prepared by the method₄The microwave ceramic material can be used as the material of electronic components such as substrates, resonant antennas and the like in microwave radio frequency systems (such as 5G/6G communication systems) and the like, compared with the conventional ceramic sintering (HTCC and L TCC) technology, the microwave ceramic material has the advantages thatThe method can not only realize densification in a lower temperature range, but also reduce carbon emission and energy consumption in the preparation and processing process.

Description

Low-temperature energy-saving preparation of L iMgPO4Method for microwave ceramic material

Technical Field

The invention relates to the technical field of communication electronic circuit component materials and low-carbon energy-saving production, in particular to a material with the component of L iMgPO₄A low-carbon energy-saving manufacturing method of microwave ceramic material.

Background

The development of 5G/6G mobile communication technology is required, in order to further provide 5G/6G communication technology with faster and more reliable broadband access, larger capacity and shorter response time delay, high-quality integrated ceramic components operating in 5G/6G frequency band are required to be developed, according to the electromagnetic propagation theory, the time delay of signal transmission depends on the dielectric constant of the dielectric material at millimeter wave frequency, the lower the dielectric constant of electromagnetic signals passing through the dielectric material is, the smaller the time delay of signal transmission and response is, in 5G/6G communication network, the dielectric constant of communication base station and terminal dielectric material plays a role in signal delay of an integral system, in addition, the temperature stability and dielectric loss of the device at the operating environment temperature are important parameters for ensuring the operating reliability of the device, therefore, the ceramic materials used in the 5G/6G devices have the critical temperature stability and dielectric loss of the device at the operating environment temperature and the critical performance of the integrated ceramic components of the high-quality and the high-temperature sintering temperature coefficient of the ceramic materials (L) which can be reduced by using microwave dielectric ceramic materials, and the ceramic materials used in the conventional sintering process of co-fired ceramic components (sintering process), and the ceramic materials, the high-temperature and the co-fired ceramic components are used in the microwave integrated ceramic materials, and the high-sintering process of high-temperature ceramic materials, and the high-temperature ceramic components (the high-temperature ceramic materials can be used in the high-temperature ceramic materials under the high-temperature and the high-temperature ceramic materials, and the high-temperature ceramic components of the high-temperature ceramic materials of the high-temperature ceramic components of the high-temperature ceramic materials.

Disclosure of Invention

The invention aims to provide a composition of L iMgPO₄The low-temperature energy-saving preparation method of the microwave ceramic material realizes that the densified ceramic with fine and uniform crystal grains and the relative density of more than or equal to 82 percent is prepared at the temperature of less than or equal to 300 ℃, and the L iMgPO is obtained by the method₄Dielectric constant of microwave ceramic material: (_r) The range is 5.4-6.5, the numerical range of the quality factor Q × f is 3,600 GHz-16,000 GHz, the range of the temperature coefficient of resonance frequency (TCF) is-46.1 ppm/DEG C-59.5 ppm/DEG C, compared with the traditional high-temperature solid phase sintering (HTCC) and low-temperature co-firing (L TCC) technology, the method has the characteristics of low sintering temperature, short sintering time and low energy consumption, and simultaneously, because of the characteristic of low-temperature sintering, the method is not easy to generate impure phases in the process.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

low-temperature energy-saving preparation of L iMgPO₄Method of microwave ceramic material L iMgPO₄Mixing with water or acetic acid not higher than 20 wt% to form a solid-liquid mixture, compacting by hot pressing at 150 deg.C, 200 deg.C, 250 deg.C or 300 deg.C, 30min, 60min or 90min, and applying pressure (P) to obtain L iMgPO₄Ceramic having a dielectric constant of_r) The range is 5.1 to 6.5, the range of the quality factor Q × f is 3,600GHz to 16,000GHz, and the range of the temperature coefficient of resonance frequency (TCF) is-46.1 ppm/DEG C to-59.5 ppm/DEG C.

The technical scheme relates to four process parameters including sintering temperature, heat preservation time, pressure and solvent type, and the method mainly comprises the following steps of 1) sintering temperature lower than 300 ℃, 2) sintering time lower than 1.5 hours, 3) pressure lower than 600MPa, 4) solvent, water and acetic acid, wherein L iMgPO prepared by the method is used as raw material₄Dielectric constant of microwave ceramic material: (_r) The range is 5.1 to 6.5, the value of the quality factor Q × f ranges from 3,600GHz to 16,000GHz, the range of the resonant frequency Temperature (TCF) ranges from-46.1 ppm/DEG C to-59.5 ppm/DEG C, and the material can be used as an electronic element such as a substrate, a resonant antenna and the like in a microwave radio frequency system (such as a 5G/6G communication system) and the likeAnd (4) using a device material.

The raw material for preparing the ceramic is basic magnesium carbonate ((MgCO)₃)₄˙Mg(OH)₂˙5H₂O), lithium carbonate (L i)₂CO₃) Ammonium dihydrogen phosphate (NH)₄H₂PO₄) The low-carbon energy-saving preparation method comprises the steps of weighing raw materials (basic magnesium carbonate, lithium carbonate and ammonium dihydrogen phosphate) according to a certain stoichiometric ratio, uniformly ball-milling, drying, and presintering to synthesize L iMgPO₄Compound powder, adding 15 wt% of water, uniformly mixing, placing the semi-dry semi-wet mixture into a mould, heating to a certain temperature in a hot press, applying pressure of 600MPa, hot-pressing for 60min, cooling, taking out a sample, and drying at 120 ℃ for 24 h to obtain compact L iMgPO₄Compared with the conventional ceramic sintering (HTCC and L TCC) technology, the method not only can realize densification in a lower temperature range, but also can reduce carbon emission and energy consumption in the preparation and processing processes of the ceramic material.

As a further improvement, the method further comprises the following steps:

(1) the ingredients are firstly mixed according to the chemical formula of L iMgPO₄The stoichiometric ratio of L i, Mg and P elements in the raw materials is L i₂CO₃(purity 99.99%), (MgCO)₃)₄˙Mg(OH)₂˙5H₂O (purity 99.99%) and NH₄H₂PO₄(purity 99.99%);

(2) mixing materials: pouring the raw materials into a ball milling tank, using isopropanol as a ball milling medium, and carrying out ball milling and mixing for 4 hours to obtain a slurry raw material;

(3) drying: pouring out the ball-milled slurry, and drying in an oven at 80 ℃ to obtain dry powder of the mixture;

(4) calcining, namely calcining the mixture dry powder obtained in the previous step in a high-temperature furnace for 4 hours at the presintering temperature of 500 ℃, and calcining the obtained powder for 4 hours at the temperature of 800 ℃ to obtain the final L iMgPO₄Block, grind and pass through a 300 mesh nylon screen.

(5) Mixing materials: adding 15 wt% of deionized water or acetic acid solution (1M) into the mixture, and mixing to obtain a dough-like aqueous mixture;

(6) and (3) low-temperature sintering: putting the aqueous mixture slurry obtained in the last step into a shape mould, moving the mould into a hot press, heating to different sintering temperature points, applying pressure under 600MPa, and carrying out hot pressing for 30 minutes, 60 minutes and 90 minutes to obtain densified ceramic;

(7) drying, namely further drying the densified ceramic sample obtained in the last step in a drying oven at the temperature of 120 ℃ for 24 hours to remove residual moisture to obtain L iMgPO₄And (5) obtaining a ceramic finished product.

In the technical scheme, L iMgPO obtained by the invention₄The ceramic material has low dielectric constant and high quality factor, the low dielectric constant can shorten the propagation delay time of electromagnetic signals and the like and minimize the cross coupling between conductors, and the high quality factor can reduce the energy loss of electric signals and improve the frequency selection precision of the resonant filter.

The invention has the beneficial effects that:

(1) the invention adopts low-temperature energy-saving technology to sinter and densify L iMgPO₄Compared with the traditional ceramic high-temperature and low-temperature solid-phase sintering, the ceramic material has the advantages of simple preparation process, lower sintering temperature, short time, energy consumption saving and pollution reduction, especially L i⁺And (5) volatilizing and polluting.

(2) The invention does not need PVA binder, takes deionized water as catalyst, mixes the powder and water, puts the mixture into a die, and sinters the mixture under the pressure of 600MPa and the temperature of less than 300 ℃, thus preparing L iMgPO with fine and uniform crystal grains and the relative density of more than or equal to 82 percent₄A ceramic.

Drawings

FIG. 1 shows L iMgPO prepared according to examples 1-4, 7 and 8 of the present invention₄(abbreviation L MP) XRD pattern of microwave ceramic material;

FIG. 2 shows L iMgPO prepared in examples 1-6 of the present invention₄Relative density drawing of microwave ceramic material；

FIG. 3 shows L iMgPO prepared by the methods of examples 3, 7 and 8 of the present invention₄Relative density attached drawing of microwave ceramic material;

FIG. 4 shows L iMgPO prepared according to examples 2, 7, 8, 9-11 of the present invention₄Relative density attached drawing of microwave ceramic material;

FIG. 5 shows L iMgPO prepared by examples 1-6 of the present invention₄Dielectric constant of microwave ceramic material: (_r) The accompanying drawings;

FIG. 6 shows L iMgPO prepared by the methods of examples 3, 7 and 8 of the present invention₄Dielectric constant of microwave ceramic material: (_r) The accompanying drawings;

FIG. 7 shows L iMgPO prepared according to examples 2, 7, 8, 9-11 of the present invention₄Dielectric constant of microwave ceramic material: (_r) The accompanying drawings;

FIG. 8 shows L iMgPO prepared by examples 1-6 of the present invention₄Figure of merit factor (Q × f) for microwave ceramic material;

FIG. 9 shows L iMgPO prepared by the methods of examples 3, 7 and 8 of the present invention₄Figure of merit factor (Q × f) for microwave ceramic material;

FIG. 10 shows L iMgPO prepared according to examples 2, 7, 8, 9-11 of the present invention₄Figure of merit factor (Q × f) for microwave ceramic material;

FIG. 11 shows L iMgPO prepared by the methods of examples 1-6 of the present invention₄The temperature coefficient of resonance frequency (TCF) diagram of the microwave ceramic material;

FIG. 12 shows L iMgPO prepared by the methods of examples 3, 7 and 8 of the present invention₄The temperature coefficient of resonance frequency (TCF) diagram of the microwave ceramic material;

FIG. 13 shows L iMgPO prepared according to examples 2, 7, 8, 9-11 of the present invention₄The temperature coefficient of resonance frequency (TCF) diagram of the microwave ceramic material;

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 a composition of L iMgPO₄Microwave ceramic material and microwave ceramic materialThe low-carbon energy-saving preparation method is specifically shown in the following examples.

Example 1 preparation of L iMgPO at 150 ℃ to 600MPa to 30min₄Microwave ceramic material

Weigh L iMgPO₄Powder 1.40g (L iMgPO prepared successfully in

steps

1, 2, 3 and 4 is weighed)₄Powder), measure deionized water (L iMgPO)₄15% of the powder mass, i.e. 0.21ml), L iMgPO was added dropwise₄Selecting a steel die with an inner hole diameter of 12mm, dipping absorbent 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, putting the water-containing mixture into the die after the die is dried, applying pressure of 600MPa by using a single-shaft press, heating the die to 150 ℃ at the heating rate of 10 ℃/min, preserving the temperature for 30min, cooling, demolding, taking out a sample, drying the obtained sample in a drying box at the temperature of 120 ℃ for 24 hours to further remove residual water to obtain L iMgPO₄XRD analysis of the product prepared in example 1, as shown in figure 1, the XRD pattern of the product prepared in example 1, which contains only pure phases, compares well with L iMgPO₄A standard PDF card (PDF #32-0574) of the crystal structure database of (1), which demonstrates the successful preparation of L iMgPO by example 1₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 1, and as shown in fig. 2, the relative density of the product prepared in example 1 was 82%. The product prepared in example 1 was subjected to dielectric constant: (_r) Testing, as shown in FIG. 5, of the product prepared in example 1_rAnd 5.4. the product prepared in example 1 was subjected to a quality factor (Q × f) test, as shown in fig. 8, and the product prepared in example 1 had a Q × f of 6,900 ghz. the product prepared in example 1 was subjected to a temperature coefficient of resonance frequency (TCF) test, as shown in fig. 11, and the product prepared in example 1 had a TCF of-46.1 ppm/° c. as can be seen from the results of the figure, the product prepared in example 1 had a high relative density and good microwave dielectric properties.

Example 2 preparation of L iMgPO at 200 ℃ -350MPa-30min₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, and then taking the powderAdding deionized water 15% (0.21 ml) of the mass of the mold into the powder, grinding uniformly to form slurry, selecting a steel mold with an inner hole diameter of 12mm, dipping absorbent cotton into absolute ethyl alcohol before using the mold, wiping the inner wall, the ejector rod and the cushion block of the mold clean respectively, weighing a proper amount of slurry into the mold after drying the mold, applying a pressure of 350MPa by using a single-shaft press, heating the mold to 200 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 30min, cooling, demolding, taking out a sample, drying the obtained sample in a drying oven at 120 ℃ for 24 hours to further remove residual moisture to obtain L iMgPO, and drying the obtained sample in the drying oven at 120 ℃ to obtain L iMgPO₄XRD analysis of the product prepared in example 2 showed that the XRD pattern of the product prepared in example 2 was pure phase, which compares well with standard PDF card PDF #32-0574 (L iMgPO) of the crystal structure database, as shown in FIG. 1₄) Matching, indicating that example 2 successfully produced L iMgPO₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 2, and as shown in fig. 2, the relative density of the product prepared in example 2 was 85%. The product prepared in example 2 was subjected to dielectric constant: (_r) Testing, as shown in FIG. 5, of the product prepared in example 2_rAnd 5.6. the product prepared in example 2 was subjected to a quality factor (Q × f) test, as shown in fig. 8, and the product prepared in example 2 had a Q × f of 14,000 ghz. the product prepared in example 2 was subjected to a temperature coefficient of resonance frequency (TCF) test, as shown in fig. 11, and the product prepared in example 2 had a TCF of-52.6 ppm/° c. as can be seen from the results of the figure, the product prepared in example 2 had a high relative density and good microwave dielectric properties.

Example 3 preparation of L iMgPO at 250 deg.C-600 MPa-30min₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, and then 15 percent (namely 0.21ml) of deionized water based on the mass of the powder is dripped into the powder and uniformly ground to form slurry. Choose the steel mould that the hole diameter is 12mm for use, dip in anhydrous alcohol with absorbent cotton earlier before the mould uses and clean mould inner wall, ejector pin, cushion respectively, treat that the mould is dry after, weigh appropriate amount thick liquids again and put into the mould, use single-shaft press to apply 600 MPa's pressure to press 10 ℃long & gtHeating the mould to 250 deg.C at min temperature rising rate, maintaining the temperature for 30min, cooling, demolding, taking out the sample, drying the obtained sample in a drying oven at 120 deg.C for 24 hr to further remove residual water to obtain L iMgPO₄XRD analysis of the product prepared in example 3, as shown in FIG. 1, the XRD pattern of the product prepared in example 3, which contains only pure phases, compares well with standard PDF card PDF #32-0574 (L iMgPO) of the crystal structure database₄) Matching, indicating that L iMgPO was successfully prepared in example 3₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 3, as shown in fig. 2, and the relative density of the product prepared in example 3 was 90%. Dielectric constant of the product prepared in example 3: (_r) Testing, as shown in FIG. 5, of the product prepared in example 2_r6.1. the product prepared in example 3 was subjected to a quality factor (Q × f) test as shown in FIG. 8, and the product prepared in example 3 had a Q × f of 12,000 GHz. the product prepared in example 3 was subjected to a temperature coefficient of resonance frequency (TCF) test as shown in FIG. 11, and the product prepared in example 3 had a TCF of-56.0 ppm/. degree.C.As can be seen from the results of the figure, the product prepared in example 3 had a high relative density and good microwave dielectric properties.

Example 4 preparation of L iMgPO at 300 deg.C-600 MPa-30min₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, then adding 15 percent (namely 0.21ml) of deionized water of the mass of the powder into the powder in a dropwise manner, uniformly grinding to form slurry, selecting a steel die with an inner hole diameter of 12mm, dipping the die with absorbent cotton into absolute ethyl alcohol before use to clean the inner wall, a mandril and a cushion block of the die respectively, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying a pressure of 600MPa by using a single-shaft press, heating the die to 300 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 30min, cooling, demolding, taking out a sample, drying the obtained sample in a drying oven at 120 ℃ for 24 hours to further remove residual moisture to obtain L iMgPO, and finally obtaining L iMgPO₄A ceramic material. XRD analysis of the product prepared in example 4, as shown in figure 1, the XRD pattern of the product prepared in example 4 contains only pure phases, and is well consistent with the number of crystal structuresStandard PDF card PDF #32-0574 (L iMgPO) of database₄) Matching, indicating that L iMgPO was successfully prepared in example 4₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 4, as shown in fig. 2, and the relative density of the product prepared in example 4 was 87%. Dielectric constant of the product prepared in example 4: (_r) Testing, as shown in FIG. 5, of the product prepared in example 4_r6.0. the product prepared in example 4 was subjected to a quality factor (Q × f) test as shown in fig. 8, and the product prepared in example 4 had a Q × f of 11,000 ghz. the product prepared in example 4 was subjected to a temperature coefficient of resonance frequency (TCF) test as shown in fig. 11, and the product prepared in example 4 had a TCF of-53.6 ppm/° c. as can be seen from the results of the figure, the product prepared in example 4 had a high relative density and good microwave dielectric properties.

Example 5 preparation of L iMgPO at 200 ℃ -350MPa-30min₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, then adding 15 percent (namely 0.21ml) of deionized water of the mass of the powder into the powder in a dropwise manner, uniformly grinding to form slurry, selecting a steel die with an inner hole diameter of 12mm, dipping the die with absorbent cotton into absolute ethyl alcohol before use to wipe the inner wall of the die, an ejector rod and a cushion block clean respectively, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying a pressure of 350MPa by using a single-shaft press, heating the die to 200 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 30min, cooling, demolding, taking out a sample, drying the obtained sample in a drying oven at 120 ℃ for 24 hours to further remove residual moisture to obtain L iMgPO, and finally obtaining L iMgPO₄XRD analysis of the product prepared in example 5, the XRD pattern of which contained only pure phases, as described in reference to example 2 of FIG. 1, compares well with standard crystal structure database PDF card PDF #32-0574 (L iMgPO)₄) Matching, indicating that L iMgPO was successfully prepared in example 5₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 5, as shown in fig. 2, and the relative density of the product prepared in example 5 was 85%. The product prepared in example 5 was subjected to dielectric constant: (_r) Test, as shown in FIG. 5, prepared in example 5Of the product_rAnd 5.6. the product prepared in example 5 was subjected to a quality factor (Q × f) test, as shown in fig. 8, and the product prepared in example 5 had a Q × f of 14,000 ghz. the product prepared in example 5 was subjected to a temperature coefficient of resonance frequency (TCF) test, as shown in fig. 11, and the product prepared in example 5 had a TCF of-50.3 ppm/° c. as can be seen from the results of the figure, the product prepared in example 5 had a high relative density and good microwave dielectric properties.

Example 6 preparation of L iMgPO at 200 deg.C-600 MPa-60min₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, then adding 15 percent (namely 0.21ml) of deionized water of the mass of the powder into the powder in a dropwise manner, uniformly grinding to form slurry, selecting a steel die with an inner hole diameter of 12mm, dipping the die with absorbent cotton into absolute ethyl alcohol before use to wipe the inner wall of the die, an ejector rod and a cushion block clean respectively, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying a pressure of 600MPa by using a single-shaft press, heating the die to 200 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 60min, cooling, demolding, taking out a sample, drying the obtained sample in a drying oven at 120 ℃ for 24 hours to further remove residual moisture to obtain L iMgPO, and finally obtaining the L iMgPO₄XRD analysis of the product prepared in example 7 and the XRD pattern of the product prepared in example 6 containing only pure phases, as described in example 2 of FIG. 1, was well suited to the crystal structure database standard PDF card PDF #32-0574 (L iMgPO)₄) Matching, indicating that L iMgPO was successfully prepared in example 7₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 7, as shown in fig. 2, and the relative density of the product prepared in example 6 was 90%. Dielectric constant of the product prepared in example 6: (_r) Testing, as shown in FIG. 5, of the product prepared in example 6_r6.1. quality factor (Q × f) test for the product prepared in example 6, as shown in FIG. 8, Q × f for the product prepared in example 6 was 10,000 GHz. temperature coefficient of resonance frequency (TCF) test for the product prepared in example 4, as shown in FIG. 11, TCF for the product prepared in example 4 was-55.8 ppm/. degree.C.As can be seen from the results of the figure, the relative position of the product prepared in example 6 was measuredHigh density, good microwave dielectric property, compatibility with silver electrode and application prospect in devices.

Example 7 preparation of L iMgPO at 250 ℃ -600MPa-60min₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, then adding 15 percent (namely 0.21ml) of deionized water of the mass of the powder into the powder in a dropwise manner, uniformly grinding to form slurry, selecting a steel die with an inner hole diameter of 12mm, dipping the die with absorbent cotton into absolute ethyl alcohol before use to wipe the inner wall of the die, an ejector rod and a cushion block clean respectively, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying a pressure of 600MPa by using a single-shaft press, heating the die to 250 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 60min, cooling, demolding, taking out a sample, drying the obtained sample in a drying oven at 120 ℃ for 24 hours to further remove residual moisture to obtain L iMgPO, and finally obtaining the L iMgPO₄XRD analysis of the product prepared in example 7, as shown in FIG. 1, the XRD pattern of the product prepared in example 8, which contains only pure phases, compares well with the standard PDF card PDF #32-0574 (L iMgPO) of the crystal structure database₄) Matching, illustrates that the example successfully produced L iMgPO₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 7, as shown in figure 3, and the relative density of the product prepared in example 8 was 93%. Dielectric constant of the product prepared in example 8: (_r) Testing, as shown in FIG. 6, of the product prepared in example 7_r6.5 quality factor (Q × f) was measured for the product prepared in example 8, as shown in FIG. 9, and Q × f was 16,000GHz for the product prepared in example 7. temperature coefficient of resonance frequency (TCF) was measured for the product prepared in example 7, as shown in FIG. 12, and the TCF was-58.0 ppm/deg.C for the product prepared in example 7. as can be seen from the results of the figure, the product prepared in example 7 had high relative density and good microwave dielectric properties.

Example 8 preparation of L iMgPO at 250 deg.C-600 MPa-90min₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, then adding deionized water accounting for 15 percent (namely 0.21ml) of the mass of the powder into the powder in a dropwise manner, and uniformly grinding to form slurrySelecting a steel die with an inner hole diameter of 12mm, dipping absorbent cotton into absolute ethyl alcohol to clean the inner wall, an ejector rod and a cushion block of the die respectively before the die is used, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying a pressure of 600MPa by using a single-shaft press, heating the die to 250 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 90min, cooling, demolding, taking out a sample, drying the obtained sample in a drying box at 120 ℃ for 24 hours to further remove residual moisture to obtain L iMgPO₄XRD analysis of the product prepared in example 10, as shown in FIG. 1, the XRD pattern of the product prepared in example 8, which contains only pure phases, compares well with the standard PDF card PDF #32-0574 (L iMgPO) of the crystal structure database₄) Matching, indicating that L iMgPO was successfully prepared in example 8₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 9, as shown in fig. 3, and the relative density of the product prepared in example 8 was 89%. Dielectric constant of the product prepared in example 9: (_r) Testing, as shown in FIG. 6, of the product prepared in example 8_r6.2 quality factor (Q × f) test was performed on the product prepared in example 8, as shown in FIG. 9, Q × f was 3,600GHz for the product prepared in example 8. temperature coefficient of resonance frequency (TCF) test was performed on the product prepared in example 8, as shown in FIG. 12, TCF was-47.0 ppm/deg.C for the product prepared in example 8. as can be seen from the results of the figure, the product prepared in example 8 had high relative density and good microwave dielectric properties.

Example 9 preparation of L iMgPO from 200 ℃ to 600MPa to 30min-acetic acid₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, and then 15 percent (namely 0.21ml) of acetic acid based on the mass of the powder is added into the powder and is uniformly ground 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 a pressure of 600MPa by using a single-shaft press, heating the die to 200 ℃ at a heating rate of 10 ℃/min, preserving the temperature for 30min, 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 L iMgPO₄XRD analysis of the product prepared in example 6 and the XRD pattern of the product prepared in example 9 containing only pure phases, as described in example 3 of FIG. 1, was well suited to the standard crystal structure database PDF card PDF #32-0574 (L iMgPO)₄) Matching, indicating that L iMgPO was successfully prepared in example 6₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 6, as shown in fig. 4, and the relative density of the product prepared in example 9 was 89%. Dielectric constant of the product prepared in example 9: (_r) Testing, as shown in FIG. 7, of the product prepared in example 6_rTo 6.1. the product prepared in example 9 was subjected to a quality factor (Q × f) test as shown in fig. 10, and the product prepared in example 9 had a Q × f of 11,000 ghz. the product prepared in example 9 was subjected to a temperature coefficient of resonance frequency (TCF) test as shown in fig. 13, and the product prepared in example 9 had a TCF of-54.9 ppm/° c. as can be seen from the results of the figure, the product prepared in example 9 had a high relative density and good microwave dielectric properties.

Example 10 preparation of L iMgPO from 250 ℃ to 600MPa to 60min-acetic acid₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, then taking 15 percent (namely 0.21ml) of acetic acid solvent of the mass of the powder to be dripped into the powder and uniformly ground to form slurry, selecting a steel die with the inner hole diameter of 12mm, dipping the degreased cotton into absolute ethyl alcohol before the die is used to wipe the inner wall, a mandril and a cushion block of the die clean respectively, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying 600MPa of pressure by using a single-shaft press, heating the die to 250 ℃ at the heating rate of 10 ℃/min, preserving the temperature for 60min, cooling, demolding, taking out a sample, drying the obtained sample in a drying oven at the temperature of 120 ℃ for 24 hours to further remove residual moisture to obtain L iMgPO, and finally obtaining the L iMgPO₄XRD analysis of the product prepared in example 10, the XRD pattern of the product prepared in example 10 containing only pure phases, as described in example 7 of FIG. 1, is well suited to the crystal structure database standard PDF card PDF #32-0574 (L iMgPO)₄) Piece of clothShows that L iMgPO was successfully prepared in example 9₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 10, and as shown in fig. 4, the relative density of the product prepared in example 10 was 93%. Dielectric constant of the product prepared in example 9: (_r) Testing, as shown in FIG. 7, of the product prepared in example 10_r6.5 quality factor (Q × f) was measured for the product prepared in example 10, as shown in FIG. 10, and Q × ff of the product prepared in example 10 was 15,000 GHz. temperature coefficient of resonance frequency (TCF) was measured for the product prepared in example 10, as shown in FIG. 13, and TCF of-59.5 ppm/deg.C for the product prepared in example 10. as can be seen from the results of the figure, the product prepared in example 10 had a high relative density and good microwave dielectric properties.

Example 11 preparation of L iMgPO from 250 ℃ to 600MPa to 90min-acetic acid₄Microwave ceramic sample

Weighing L iMgPO₄1.40g of powder, then adding 15 percent (namely 0.21ml) of acetic acid solvent of the mass of the powder into the powder in a dropwise manner and uniformly grinding to form slurry, selecting a steel die with an inner hole diameter of 12mm, dipping the die with absorbent cotton into absolute ethyl alcohol before use to wipe the inner wall, a mandril and a cushion block of the die clean respectively, weighing a proper amount of slurry after the die is dried, putting the slurry into the die, applying a pressure of 600MPa by using a single-shaft press, heating the die to 250 ℃ at a heating rate of 10 ℃/min, preserving the temperature for 90min, cooling, demolding, taking out a sample, drying the obtained sample in a drying oven at 120 ℃ for 24 hours to further remove residual moisture to obtain L iMgPO, and finally obtaining L iMgPO₄XRD analysis of the product prepared in example 11, the XRD pattern of the product prepared in example 11 containing only pure phases, as described in example 8 of FIG. 1, compares well with the crystal structure database standard PDF card PDF #32-0574 (L iMgPO)₄) Matching, indicating that L iMgPO was successfully prepared in example 11₄Microwave ceramic material. The relative density calculation was performed on the product prepared in example 11, and as shown in fig. 4, the relative density of the product prepared in example 11 was 80%. Dielectric constant of the product prepared in example 9: (_r) Testing, as shown in FIG. 7, of the product prepared in example 11_rTo 5.1, the product prepared in example 11 was subjected to a quality factor (Q × f) test as shown in fig. 10, and the product prepared in example 11 had a Q × f of 10,000ghz, and the product prepared in example 11 was subjected to a temperature coefficient of resonance frequency (TCF) test as shown in fig. 13, and the product prepared in example 11 had a TCF of-49.0 ppm/° c.

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. Low-temperature energy-saving preparation of L iMgPO₄The microwave ceramic material is prepared with L iMgPO₄Mixing with water or acetic acid not higher than 20 wt% to form a solid-liquid mixture, compacting by hot pressing at 150 deg.C, 200 deg.C, 250 deg.C or 300 deg.C, 30min, 60min or 90min, and applying pressure (P) to obtain L iMgPO₄Ceramic having a dielectric constant of_r) The range is 5.1 to 6.5, the range of the quality factor Q × f is 3,600GHz to 16,000GHz, and the range of the temperature coefficient of resonance frequency (TCF) is-46.1 ppm/DEG C to-59.5 ppm/DEG C.

2. The method of claim 1, comprising the steps of:

(4) calcining, namely calcining the mixture dry powder obtained in the previous step in a high-temperature furnace for 4 hours at the presintering temperature of 500 ℃, and calcining the obtained powder for 4 hours at the temperature of 800 ℃ to obtain the final L iMgPO₄Block, grinding and sieving with 300 mesh nylon sieve;

(5) mixing materials, weighing L iMgPO₄Adding 15 wt% of deionized water into the powder, and uniformly mixing to form a dough-like aqueous mixture;

(6) and (3) low-temperature sintering: placing the water-containing mixture obtained in the last step into a shape mould, moving the mould into a hot press, heating to a certain sintering temperature point of not more than 300 ℃, applying 600MPa pressure to the mould, and carrying out hot pressing for 30, 60 and 90 minutes to obtain densified ceramic;