Low-temperature sintered microwave dielectric material and preparation method thereof

Abstract

The invention relates to the field of electronic information functional ceramics and electronic devices, and discloses a low-temperature sintered microwave dielectric material and a preparation method thereof.The composition expression of the microwave dielectric material is xLi [Mg0. 98 (Li2 / 3Sn1 / 3) 0.02] 3TiO6-(1-x) Ca0. 8Sm0. 4 / 3TiO3 + ywt.% MO, MO is a sintering aid, x is larger than or equal to 0.1 and smaller than or equal to 0.5, y is larger than or equal to 0.4 and smaller than or equal to 1, y is larger than or equal to 0.4 and smaller than or equal to 1, and y is larger than or equal to 1 and smaller than or equal to 1. A microwave dielectric ceramic material prepared from the prepared microwave dielectric material at the sintering temperature of 1100-1250 DEG C has excellent microwave dielectric properties, the dielectric constant can reach 40-55, the Q * f value can reach 45000-60000 GHz, and the frequency temperature coefficient tau f can reach 0.8-4.9 ppm / DEG C.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic information functional ceramics and electronic devices, and particularly relates to a low-temperature sintered microwave dielectric material and a preparation method thereof. Background Art

[0002] Microwave dielectric ceramic materials refer to ceramic materials that are used as dielectric materials in the 300MHz to 300GHz band and perform one or more functions. In modern communications, they are widely used in microwave components such as resonators, filters, capacitors and dielectric waveguide circuits. They are indispensable core materials for different applications such as millimeter wave communications, electronic circuit packaging, dielectric resonant antennas, base station communications and miniaturized mobile communications.

[0003] Ceramic materials with a medium dielectric constant and high quality factor are primarily used in the manufacture of high-end microwave components such as dielectric resonators, dielectric filters, GPS antennas, and ring isolators. Their high quality factor and relatively high dielectric constant enable microwave components to maintain excellent electrical performance while miniaturizing electronic components. With the continuous advancement of communication technology and the increasing awareness of environmental protection, the electronics industry's requirements for the quality of electronic devices are also constantly increasing. Ideal microwave dielectric ceramic materials should possess an appropriate dielectric constant, low dielectric loss, a high quality factor, and a resonant frequency temperature coefficient approaching zero.

[0004] At present, dielectric ceramic materials such as (Zr,Sn)TiO4, BaO-TiO2 and CaTiO3-NdAlO3 have been maturely studied and put into commercial production, but these systems still have shortcomings: (Zr,Sn)TiO4 ceramics are prone to oxygen vacancy defects due to the high sintering temperature, which increases dielectric loss; the stoichiometric ratio and sintering range of BaO-TiO2 ceramics are very narrow and difficult to control, and they are prone to produce second phases that deteriorate dielectric properties; the preparation of CaTiO3-NdAlO3 ceramics mainly has the defects of high sintering temperature and unstable performance. Therefore, there is an urgent need for a microwave dielectric material with a low sintering temperature, a suitable dielectric constant, a quality factor as high as possible, and a resonant frequency temperature coefficient close to zero. Summary of the Invention

[0005] In order to address the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a low-temperature sintered microwave dielectric material and a preparation method thereof. The microwave dielectric ceramic material prepared at a sintering temperature of 1100-1250°C has excellent microwave dielectric properties: the dielectric constant can reach 40-55, the Q×f value can reach 45000-60000 GHz, and the frequency temperature coefficient τf can reach 0.8-4.9 ppm / °C.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A low-temperature sintered microwave dielectric material, the composition expression of the microwave dielectric material is: xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 TiO3+ywt.%MO, MO is a sintering aid, wherein: 0.1≤x≤0.5, 0.4≤y≤1, and the sintering temperature of the microwave dielectric material is 1100-1250°C.

[0008] Preferably, the sintering aids are Li2B4O7 and ZnO, and the molar ratio of Li2B4O7 to ZnO is 1:1.

[0009] Preferably, the preparation method of the sintering aid comprises the following steps: lithium carbonate, boron oxide and zinc oxide powders are prepared in proportion and added into a ball mill, ball milled at a speed of 150 r / min for 2 hours, the ball milled slurry is dried and passed through a 200 mesh sieve to obtain a mixed powder raw material, which is then loaded into an alumina crucible, heated to 800°C at 4°C / min and kept warm for 2 hours, and then cooled to obtain a sintering aid.

[0010] Preferably, the microwave dielectric material has a dielectric constant of 40 to 55, a Q×f value of 45,000 to 60,000 GHz, and a frequency temperature coefficient τf of 0.8 to 4.9 ppm / °C.

[0011] Preferably, when x=0.1, the dielectric constant of the microwave dielectric material is 53.5, the Q×f value is 45300 GHz, and the frequency temperature coefficient τf is 4.9 ppm / °C; when x=0.33, the dielectric constant of the microwave dielectric material is 48.0, the Q×f value is 52140 GHz, and the frequency temperature coefficient τf is 2.6 ppm / °C; when x=0.5, the dielectric constant of the microwave dielectric material is 40.3, the Q×f value is 59800 GHz, and the frequency temperature coefficient τf is 0.8 ppm / °C.

[0012] A method for preparing a low-temperature sintered microwave dielectric material comprises the following steps:

[0013] S1. Ingredients: Lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide, calcium carbonate, samarium trioxide as raw materials, first according to Li2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6 composition expression: Weigh lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide and mix them evenly to obtain a mixture; according to Ca 0.8 Sm0.4 / 3 Composition Expression of TiO3 Calcium carbonate, samarium trioxide, and titanium dioxide are weighed and mixed uniformly to obtain mixture 2;

[0014] S2, mixing: ball-milling the mixed material 1 and the mixed material 2, mixing and pulverizing them, and drying them to obtain a dry powder 1 and a dry powder 2;

[0015] S3, pre-calcination: placing the dry powder material 1 and the dry powder material 2 in an alumina crucible respectively, and calcining them at high temperature in a pre-calcination furnace to obtain synthetic material 1 and synthetic material 2;

[0016] S4, secondary batching: according to xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 The composition expression of TiO3 is as follows: according to the value of x, synthetic material 1 and synthetic material 2 are weighed respectively, and then 0.4-1 wt.% of sintering aid is added to obtain a mixed material;

[0017] S5. Mixing and grinding: mixing and grinding the mixed materials in a ball mill using zirconium balls and deionized water as the milling media to obtain a mixed slurry;

[0018] S6, slurry granulation: adding 2 to 5 wt% of a polyvinyl alcohol binder to the mixed slurry, and then spray granulating to obtain granulated powder;

[0019] S7. Molding and sintering: The granulated powder is pressed and molded to obtain a green body, which is placed in a box-type electric furnace to increase temperature and remove binder, and then placed in a muffle furnace to be sintered into porcelain to prepare a microwave dielectric material.

[0020] Preferably, in step S2, the ball milling media are zirconium balls and ethanol, the mass ratio of the first mixture, ethanol and zirconium balls is 1:3:10, and the mass ratio of the second mixture, ethanol and zirconium balls is 1:3:10.

[0021] Preferably, the pre-firing temperature in step S3 is 1000-1150° C., and the pre-firing time is 3-4 hours.

[0022] Preferably, the debinding temperature in step S7 is 550-600° C., the heating rate is 3-5° C. / min, and the temperature is kept for 1-2 hours.

[0023] Preferably, the sintering temperature in step S7 is 1100-1250°C.

[0024] Beneficial effects of the present invention:

[0025] The present invention uses lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide, calcium carbonate, samarium trioxide to prepare the formula xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 TiO3 microwave dielectric material, using (Li 2 / 3 Sn 1 / 3 ) 2+ Ion substitution Mg 2+ The Li2Mg3TiO6 ceramics were modified by ion doping to improve the dielectric properties of microwave dielectric materials, and the low melting point sintering aids Li2B4O7 and ZnO were added to reduce the sintering temperature of microwave dielectric materials. 2 / 3 Sn 1 / 3 ) 2+ When the doping amount is 0.02 mol%, the microwave dielectric ceramic material sintered at 1100-1250°C obtains excellent microwave dielectric properties: the dielectric constant can reach 40-55, the Q×f value can reach 45000-60000 GHz, and the frequency temperature coefficient τf can reach 0.8-4.9 ppm / °C. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Example 1 A method for preparing a sintering aid comprises the following steps:

[0028] Lithium carbonate, boron oxide and zinc oxide powders were prepared in proportion to 50% Li2B4O7 and 50% ZnO (molar fraction) and added to a ball mill. The mixture was ball milled at a speed of 150 r / min for 2 h. After the ball milled slurry was dried, it was sieved through a 200-mesh sieve to obtain a mixed powder raw material. The raw material was then loaded into an alumina crucible, heated to 800°C at 4°C / min and kept warm for 2 h. After cooling, a sintering aid was prepared.

[0029] Example 2 A method for preparing a low-temperature sintered microwave dielectric material comprises the following steps:

[0030] S1. Ingredients: Lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide, calcium carbonate, samarium trioxide as raw materials, first according to Li2[Mg 0.98 (Li 2 / 3 Sn 1 / 3) 0.02 ]3TiO6 composition expression: Weigh lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide and mix them evenly to obtain a mixture; according to Ca 0.8 Sm 0.4 / 3 Composition Expression of TiO3 Calcium carbonate, samarium trioxide, and titanium dioxide are weighed and mixed uniformly to obtain mixture 2;

[0031] S2. Mixing: Mixture 1 and mixture 2 are respectively subjected to ball milling, mixed and crushed, and dried to obtain dry powder 1 and dry powder 2. The ball milling media are zirconium balls and ethanol. The mass ratio of mixture 1, ethanol and zirconium balls is 1:3:10, and the mass ratio of mixture 2, ethanol and zirconium balls is 1:3:10.

[0032] S3, pre-calcination: dry powder material 1 and dry powder material 2 are placed in alumina crucibles respectively, and calcined in a pre-calcination furnace at 1100° C. for 3 hours to obtain synthetic material 1 and synthetic material 2;

[0033] S4, secondary batching: according to xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 Composition expression of TiO3, when x is 0.1, synthetic material 1 and synthetic material 2 are weighed separately, and then 1 wt.% of the sintering aid prepared in Example 1 is added to obtain a mixed material;

[0034] S5. Mixing and grinding: The mixed materials are mixed and ground in a ball mill. The ball milling media are zirconium balls and deionized water. The mass ratio of zirconium balls, mixed materials, and deionized water is 10:1:3. The ball milling speed is 200 r / min and the ball milling time is 24 h to obtain a mixed slurry.

[0035] S6, slurry granulation: adding 4 wt% of polyvinyl alcohol binder to the mixed slurry, and then spray granulating to obtain granulated powder;

[0036] S7. Molding and sintering: The granulated powder is pressed and molded to obtain a green body, which is placed in a box-type electric furnace and heated to 600°C at 3°C / min and kept warm for 1 hour for debinding, and then placed in a muffle furnace and heated to 1100°C at 5°C / min to sinter into porcelain, thereby preparing a microwave dielectric material.

[0037] Example 3 A method for preparing a low-temperature sintered microwave dielectric material comprises the following steps:

[0038] S1. Ingredients: Lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide, calcium carbonate, samarium trioxide as raw materials, first according to Li2[Mg 0.98(Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6 composition expression: Weigh lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide and mix them evenly to obtain a mixture; according to Ca 0.8 Sm 0.4 / 3 Composition Expression of TiO3 Calcium carbonate, samarium trioxide, and titanium dioxide are weighed and mixed uniformly to obtain mixture 2;

[0039] S2. Mixing: Mixture 1 and mixture 2 are respectively subjected to ball milling, mixed and crushed, and dried to obtain dry powder 1 and dry powder 2. The ball milling media are zirconium balls and ethanol. The mass ratio of mixture 1, ethanol and zirconium balls is 1:3:10, and the mass ratio of mixture 2, ethanol and zirconium balls is 1:3:10.

[0040] S3, pre-calcination: dry powder material 1 and dry powder material 2 are placed in alumina crucibles respectively, and calcined in a pre-calcination furnace at 1100° C. for 3 hours to obtain synthetic material 1 and synthetic material 2;

[0041] S4, secondary batching: according to xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 Composition expression of TiO3, when x is 0.33, synthetic material 1 and synthetic material 2 are weighed separately, and then 1 wt.% of the sintering aid prepared in Example 1 is added to obtain a mixed material;

[0042] S5. Mixing and grinding: The mixed materials are mixed and ground in a ball mill. The ball milling media are zirconium balls and deionized water. The mass ratio of zirconium balls, mixed materials, and deionized water is 10:1:3. The ball milling speed is 200 r / min and the ball milling time is 24 h to obtain a mixed slurry.

[0043] S6, slurry granulation: adding 4 wt% of polyvinyl alcohol binder to the mixed slurry, and then spray granulating to obtain granulated powder;

[0044] S7. Molding and sintering: The granulated powder is pressed and molded to obtain a green body, which is placed in a box-type electric furnace and heated to 600°C at 3°C / min and kept warm for 1 hour for debinding, and then placed in a muffle furnace and heated to 1100°C at 5°C / min to sinter into porcelain, thereby preparing a microwave dielectric material.

[0045] Example 4 A method for preparing a low-temperature sintered microwave dielectric material comprises the following steps:

[0046] S1. Ingredients: Lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide, calcium carbonate, samarium trioxide as raw materials, first according to Li2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6 composition expression: Weigh lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide and mix them evenly to obtain a mixture; according to Ca 0.8 Sm 0.4 / 3 Composition Expression of TiO3 Calcium carbonate, samarium trioxide, and titanium dioxide are weighed and mixed uniformly to obtain mixture 2;

[0047] S2. Mixing: Mixture 1 and mixture 2 are respectively subjected to ball milling, mixed and crushed, and dried to obtain dry powder 1 and dry powder 2. The ball milling media are zirconium balls and ethanol. The mass ratio of mixture 1, ethanol and zirconium balls is 1:3:10, and the mass ratio of mixture 2, ethanol and zirconium balls is 1:3:10.

[0048] S3, pre-calcination: dry powder material 1 and dry powder material 2 are placed in alumina crucibles respectively, and calcined in a pre-calcination furnace at 1100° C. for 3 hours to obtain synthetic material 1 and synthetic material 2;

[0049] S4, secondary batching: according to xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 Composition expression of TiO3, when x is 0.5, synthetic material 1 and synthetic material 2 are weighed separately, and then 1 wt.% of the sintering aid prepared in Example 1 is added to obtain a mixed material;

[0050] S5. Mixing and grinding: The mixed materials are mixed and ground in a ball mill. The ball milling media are zirconium balls and deionized water. The mass ratio of zirconium balls, mixed materials, and deionized water is 10:1:3. The ball milling speed is 200 r / min and the ball milling time is 24 h to obtain a mixed slurry.

[0051] S6, slurry granulation: adding 4 wt% of polyvinyl alcohol binder to the mixed slurry, and then spray granulating to obtain granulated powder;

[0052] S7. Molding and sintering: The granulated powder is pressed and molded to obtain a green body, which is placed in a box-type electric furnace and heated to 600°C at 3°C / min and kept warm for 1 hour for debinding, and then placed in a muffle furnace and heated to 1100°C at 5°C / min to sinter into porcelain, thereby preparing a microwave dielectric material.

[0053] Example 5 A method for preparing a low-temperature sintered microwave dielectric material comprises the following steps:

[0054] S1. Ingredients: Lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide, calcium carbonate, samarium trioxide as raw materials, first according to Li2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6 composition expression: Weigh lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide and mix them evenly to obtain a mixture; according to Ca 0.8 Sm 0.4 / 3 Composition Expression of TiO3 Calcium carbonate, samarium trioxide, titanium dioxide, magnesium oxide, and niobium pentoxide are weighed and mixed uniformly to obtain mixture 2;

[0055] S2. Mixing: Mixture 1 and mixture 2 are respectively subjected to ball milling, mixed and crushed, and dried to obtain dry powder 1 and dry powder 2. The ball milling media are zirconium balls and ethanol. The mass ratio of mixture 1, ethanol and zirconium balls is 1:3:10, and the mass ratio of mixture 2, ethanol and zirconium balls is 1:3:10.

[0056] S3, pre-calcination: dry powder material 1 and dry powder material 2 are placed in alumina crucibles respectively, and calcined in a pre-calcination furnace at 1100° C. for 3 hours to obtain synthetic material 1 and synthetic material 2;

[0057] S4, secondary batching: according to xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 Composition expression of TiO3, when x is 0.33, synthetic material 1 and synthetic material 2 are weighed separately, and then 1 wt.% of the sintering aid prepared in Example 1 is added to obtain a mixed material;

[0058] S5. Mixing and grinding: The mixed materials are mixed and ground in a ball mill. The ball milling media are zirconium balls and deionized water. The mass ratio of zirconium balls, mixed materials, and deionized water is 10:1:3. The ball milling speed is 200 r / min and the ball milling time is 24 h to obtain a mixed slurry.

[0059] S6, slurry granulation: adding 4 wt% of polyvinyl alcohol binder to the mixed slurry, and then spray granulating to obtain granulated powder;

[0060] S7. Molding and sintering: The granulated powder is pressed and molded to obtain a green body, which is placed in a box-type electric furnace and heated to 600°C at 3°C / min and kept warm for 1 hour for debinding. The green body is then placed in a muffle furnace and heated to 1200°C at 5°C / min to sinter into porcelain, thereby preparing a microwave dielectric material.

[0061] Example 6 A method for preparing a low-temperature sintered microwave dielectric material comprises the following steps:

[0062] S1. Ingredients: Lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide, calcium carbonate, samarium trioxide as raw materials, first according to Li2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6 composition expression: Weigh lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide and mix them evenly to obtain a mixture; according to Ca 0.8 Sm 0.4 / 3 Composition Expression of TiO3 Calcium carbonate, samarium trioxide, and titanium dioxide are weighed and mixed uniformly to obtain mixture 2;

[0063] S2. Mixing: Mixture 1 and mixture 2 are respectively subjected to ball milling, mixed and crushed, and dried to obtain dry powder 1 and dry powder 2. The ball milling media are zirconium balls and ethanol. The mass ratio of mixture 1, ethanol and zirconium balls is 1:3:10, and the mass ratio of mixture 2, ethanol and zirconium balls is 1:3:10.

[0064] S3, pre-calcination: dry powder material 1 and dry powder material 2 are placed in alumina crucibles respectively, and calcined in a pre-calcination furnace at 1100° C. for 3 hours to obtain synthetic material 1 and synthetic material 2;

[0065] S4, secondary batching: according to xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 Composition expression of TiO3, when x is 0.33, synthetic material 1 and synthetic material 2 are weighed separately, and then 1 wt.% of the sintering aid prepared in Example 1 is added to obtain a mixed material;

[0066] S5. Mixing and grinding: The mixed materials are mixed and ground in a ball mill. The ball milling media are zirconium balls and deionized water. The mass ratio of zirconium balls, mixed materials, and deionized water is 10:1:3. The ball milling speed is 200 r / min and the ball milling time is 24 h to obtain a mixed slurry.

[0067] S6, slurry granulation: adding 4 wt% of polyvinyl alcohol binder to the mixed slurry, and then spray granulating to obtain granulated powder;

[0068] S7. Molding and sintering: The granulated powder is pressed and molded to obtain a green body, which is placed in a box-type electric furnace and heated to 600°C at 3°C / min and kept warm for 1 hour for debinding, and then placed in a muffle furnace and heated to 1250°C at 5°C / min to sinter into porcelain, thereby preparing a microwave dielectric material.

[0069] Example 7 A method for preparing a low-temperature sintered microwave dielectric material comprises the following steps:

[0070] S1. Ingredients: Lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide, calcium carbonate, samarium trioxide as raw materials, first according to Li2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6 composition expression: Weigh lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide and mix them evenly to obtain a mixture; according to Ca 0.8 Sm 0.4 / 3 Composition Expression of TiO3 Calcium carbonate, samarium trioxide, and titanium dioxide are weighed and mixed uniformly to obtain mixture 2;

[0071] S2. Mixing: Mixture 1 and mixture 2 are respectively subjected to ball milling, mixed and crushed, and dried to obtain dry powder 1 and dry powder 2. The ball milling media are zirconium balls and ethanol. The mass ratio of mixture 1, ethanol and zirconium balls is 1:3:10, and the mass ratio of mixture 2, ethanol and zirconium balls is 1:3:10.

[0072] S3, pre-calcination: dry powder material 1 and dry powder material 2 are placed in alumina crucibles respectively, and calcined in a pre-calcination furnace at 1100° C. for 3 hours to obtain synthetic material 1 and synthetic material 2;

[0073] S4, secondary batching: according to xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 Composition expression of TiO3, when x is 0.33, synthetic material 1 and synthetic material 2 are weighed separately, and then 0.5 wt.% of the sintering aid prepared in Example 1 is added to obtain a mixed material;

[0074] S5. Mixing and grinding: The mixed materials are mixed and ground in a ball mill. The ball milling media are zirconium balls and deionized water. The mass ratio of zirconium balls, mixed materials, and deionized water is 10:1:3. The ball milling speed is 200 r / min and the ball milling time is 24 h to obtain a mixed slurry.

[0075] S6, slurry granulation: adding 4 wt% of polyvinyl alcohol binder to the mixed slurry, and then spray granulating to obtain granulated powder;

[0076] S7. Molding and sintering: The granulated powder is pressed and molded to obtain a green body, which is placed in a box-type electric furnace and heated to 600°C at 3°C / min and kept warm for 1 hour for debinding, and then placed in a muffle furnace and heated to 1125°C at 5°C / min to sinter into porcelain, thereby preparing a microwave dielectric material.

[0077] Performance testing

[0078] The microwave dielectric materials prepared in Examples 2-7 were subjected to performance testing: the dielectric constant (εr), quality factor (Q×f) and resonant frequency temperature coefficient (τf) of the samples were tested using a microwave network analyzer; the resonant frequency f(T) at temperature T was measured, and the resonant frequency temperature coefficient was calculated using the formula: τf=(f T2 -f T1 ) / [f T2 ×(T2-T1)], where T2 is 85°C and T1 is 25°C. The data results are shown in Table 1.

[0079] Table 1 Sample performance test results

[0080]

[0081] It can be seen from the data in Table 1 that the microwave dielectric ceramic materials prepared in Examples 2-7 of the present invention at a sintering temperature of 1100-1250°C have excellent microwave dielectric properties: the dielectric constant can reach 40-55, the Q×f value can reach 45000-60000 GHz, and the frequency temperature coefficient τf can reach 0.8-4.9 ppm / °C.

[0082] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0083] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A low-temperature sintered microwave dielectric material, characterized in that: The composition expression of the microwave dielectric material is: xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 TiO3+ywt.%MO, MO is a sintering aid, wherein: 0.1≤x≤0.5, 0.4≤y≤1, and the sintering temperature of the microwave dielectric material is 1100-1250°C.

2. The low-temperature sintered microwave dielectric material according to claim 1, characterized in that: The sintering aids are Li2B4O7 and ZnO, and the molar ratio of Li2B4O7 to ZnO is 1:

1.

3. The low-temperature sintered microwave dielectric material according to claim 2, characterized in that: The preparation method of the sintering aid comprises the following steps: lithium carbonate, boron oxide and zinc oxide powders are mixed in proportion and added into a ball mill, ball milled at a speed of 150 r / min for 2 hours, the ball milled slurry is dried and passed through a 200-mesh sieve to obtain a mixed powder raw material, which is then placed into an alumina crucible, heated to 800° C. at a speed of 4° C. / min and kept at that temperature for 2 hours, and then cooled to obtain the sintering aid.

4. The low-temperature sintered microwave dielectric material according to claim 1, characterized in that: The microwave dielectric material has a dielectric constant of 40 to 55, a Q×f value of 45,000 to 60,000 GHz, and a frequency temperature coefficient τf of 0.8 to 4.9 ppm / °C.

5. The low-temperature sintered microwave dielectric material according to claim 1, characterized in that: When x=0.1, the dielectric constant of the microwave dielectric material is 53.5, the Q×f value is 45300 GHz, and the frequency temperature coefficient τf is 4.9 ppm / °C. When x=0.33, the dielectric constant of the microwave dielectric material is 48.0, the Q×f value is 52140 GHz, and the frequency temperature coefficient τf is 2.6 ppm / °C. When x=0.5, the dielectric constant of the microwave dielectric material is 40.3, the Q×f value is 59800 GHz, and the frequency temperature coefficient τf is 0.8 ppm / °C.

6. A method for preparing a low-temperature sintered microwave dielectric material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Ingredients: Lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide, calcium carbonate, samarium trioxide as raw materials, first according to Li2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6 composition expression: Weigh lithium carbonate, magnesium oxide, tin dioxide, titanium dioxide and mix them evenly to obtain a mixture; according to Ca 0.8 Sm 0.4 / 3 Composition Expression of TiO3 Calcium carbonate, samarium trioxide, and titanium dioxide are weighed and mixed uniformly to obtain mixture 2; S2, mixing: ball-milling the mixed material 1 and the mixed material 2, mixing and pulverizing them, and drying them to obtain a dry powder 1 and a dry powder 2; S3, pre-calcination: placing the dry powder material 1 and the dry powder material 2 in an alumina crucible respectively, and calcining them at high temperature in a pre-calcination furnace to obtain synthetic material 1 and synthetic material 2; S4, secondary batching: according to xLi2[Mg 0.98 (Li 2 / 3 Sn 1 / 3 ) 0.02 ]3TiO6-(1-x)Ca 0.8 Sm 0.4 / 3 The composition expression of TiO3 is as follows: according to the value of x, synthetic material 1 and synthetic material 2 are weighed respectively, and then 0.4-1 wt.% of sintering aid is added to obtain a mixed material; S5. Mixing and grinding: mixing and grinding the mixed materials in a ball mill using zirconium balls and deionized water as the milling media to obtain a mixed slurry; S6, slurry granulation: adding 2 to 5 wt% of a polyvinyl alcohol binder to the mixed slurry, and then spray granulating to obtain granulated powder; S7. Molding and sintering: The granulated powder is pressed and molded to obtain a green body, which is placed in a box-type electric furnace to increase temperature and remove binder, and then placed in a muffle furnace to be sintered into porcelain to prepare a microwave dielectric material.

7. The method for preparing a low-temperature sintered microwave dielectric material according to claim 6, characterized in that: In step S2, the ball milling media are zirconium balls and ethanol, the mass ratio of the first mixture, ethanol and zirconium balls is 1:3:10, and the mass ratio of the second mixture, ethanol and zirconium balls is 1:3:

10.

8. The method for preparing a low-temperature sintered microwave dielectric material according to claim 6, characterized in that: In step S3, the pre-firing temperature is 1000-1150° C., and the pre-firing time is 3-4 hours.

9. The method for preparing a low-temperature sintered microwave dielectric material according to claim 6, characterized in that: In step S7, the debinding temperature is 550-600° C., the heating rate is 3-5° C. / min, and the temperature is kept for 1-2 hours.

10. The method for preparing a low-temperature sintered microwave dielectric material according to claim 6, characterized in that: The sintering temperature in step S7 is 1100-1250°C.

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