Disclosure of Invention
The invention provides a high-Q-value lithium titanate-based microwave dielectric ceramic material and a preparation method thereof, and aims to solve the problem of pure Li2TiO3By applying Li to the technical problem that the Qf value of (B) does not meet the production requirements2TiO3Different dopants are added to improve the ceramic crystal phase and promote the densification and sintering of the ceramic, thereby improving Li2TiO3To improve the quality factor of lithium titanate. .
The invention is realized by the following technical scheme:
according to one aspect of the invention, a high-Q-value lithium titanate-based microwave dielectric ceramic material is provided, and the chemical formula of the high-Q-value lithium titanate-based microwave dielectric ceramic material is Li2TiO3+ xM, wherein M is Li2CO3、MgO、LiF、MgF2Or MgO + LiF, x being M in Li2TiO3X is 1 wt.% to 3 wt.%.
Further, in the case where M is MgO + LiF, the molar ratio of MgO to LiF is 1: 2.
according to another aspect of the present invention, there is provided a preparation method of the above high-Q lithium titanate-based microwave dielectric ceramic material, the method comprises the following steps:
(1) mixing Li2CO3And TiO2In stoichiometric formula Li2TiO3Mixing materials, namely performing ball milling on the mixed materials, deionized water and grinding balls in a ball milling tank for 4-24 hours;
(2) drying the raw materials obtained after ball milling in the step (1), and sieving the dried raw materials with a 40-mesh sieve;
(3) putting the powder sieved in the step (2) into a crucible for presintering at 800-1000 ℃, preserving heat for 2-8 hours, and then sieving with a 40-mesh sieve;
(4) adding M dopant into the powder sieved in the step (3) according to the mass percentage of x, wherein M is Li2CO3、MgO、LiF、MgF2Or MgO + LiF, x 1 wt.% to 3 wt.%; carrying out ball milling on the mixed ingredients added with the M dopant, deionized water and the milling balls in a ball milling tank for 4-24 hours;
(5) drying the raw materials obtained after ball milling in the step (4), and sieving the dried raw materials with a 40-mesh sieve;
(6) adding a binder into the powder obtained in the step (5) for granulation, and sieving the powder with a 80-mesh sieve;
(7) pressing the powder obtained in the step (6) into a green body;
(8) and (4) sintering the green body obtained in the step (7) at 1100-1180 ℃, and preserving heat for 2-8 hours to obtain the high-Q-value lithium titanate-based microwave dielectric ceramic material.
Further, ball milling is carried out in the steps (1) and (4) by adopting a planetary ball mill, and the rotating speed of the ball mill is 400 r/m; the grinding balls are zirconia balls, and the ball milling tanks are polyester ball milling tanks.
Furthermore, the mass ratio of the mixed ingredients, the deionized water and the zirconia balls in the step (1) and the step (4) is 1:30: 15.
Further, the drying temperature in the step (2) and the drying time in the step (5) are both 100-120 ℃, and the drying time is both 4-6 hours.
Further, the crucible in the step (3) is an alumina crucible.
Further, the binder in the step (6) is paraffin with the mass percent content of 8%.
And (3) further, pressing the green body by using a powder tablet press in the step (7), wherein the working pressure of the powder tablet press is 2-6 MPa.
Further, the diameter of the green body in the step (7) is 10mm, and the thickness of the green body is 4-5 mm.
The invention has the beneficial effects that:
the invention is in Li2TiO3Based on a microwave dielectric material system, by adding Li2TiO3Into which different kinds of dopants, including Li, are introduced2CO3MgO, LiF and MgF, improves the sintering characteristic of the microwave dielectric ceramic, and compares with pure Li2TiO3The Qf value (Qf-63,000) is greatly improved, and Li is prepared2TiO3+ xM microwave dielectric material, where M is Li2CO3、MgO、LiF、MgF2Or MgO + LiF, wherein x is the mass percent, and x is 0.6 wt.% to 3.6 wt.%. Under the microwave frequency band, the material product has higher quality factor Qf value 103406-156398 GHz and moderate dielectric constant epsilonrThe value is 19.474-24.9112, the preparation process of the ceramic system is simple, and the microwave dielectric device manufactured and researched by the ceramic system has wide application prospect.
Detailed Description
The invention is described in further detail below by means of specific examples and comparative examples:
example 1
(1) Mixing Li2CO3And TiO2The molar ratio of the massage is Li2CO3And TiO21: 1, proportioning, namely putting powder into a polyester ball milling tank, wherein the mass ratio of the raw materials to deionized water and zirconia balls is 1:30:15, and carrying out ball milling on a planetary ball mill for 6 hours at the ball milling rotating speed of 400/min;
(2) putting the ball-milled raw materials in the step (1) into a drying oven, drying for 4 hours at 120 ℃, and then sieving by a 40-mesh sieve;
(3) putting the powder sieved in the step (2) into a medium temperature furnace, presintering at 900 ℃, preserving heat for 4 hours, and synthesizing Li2TiO3Then sieving the mixture by a 40-mesh sieve;
(4) adding 8 mass percent of paraffin wax as an adhesive into the powder sieved in the step (3) for granulation, and sieving the powder with a 80-mesh sieve;
(5) pressing the powder material obtained in the step (4) into a green body by using a powder tablet press under the pressure of 2 MPa;
(6) sintering the green body obtained in the step (5) at 1140 ℃, and preserving heat for 4 hours to obtain the lithium titanate-based microwave dielectric ceramic material of the embodiment;
(7) the microwave dielectric properties of the articles obtained in this example were tested by a network analyzer.
Example 2
(1) Mixing Li2CO3And TiO2The molar ratio of the massage is Li2CO3And TiO21: 1, proportioning, namely putting powder into a polyester ball milling tank, wherein the mass ratio of the raw materials to deionized water and zirconia balls is 1:30:15, and carrying out ball milling on a planetary ball mill for 6 hours at the ball milling rotating speed of 400/min;
(2) putting the ball-milled raw materials in the step (1) into a drying oven, drying for 4 hours at 120 ℃, and then sieving by a 40-mesh sieve;
(3) putting the powder sieved in the step (2) into a medium temperature furnace, presintering at 850 ℃, preserving heat for 4 hours, and synthesizing Li2TiO3Then sieving the mixture by a 40-mesh sieve;
(4) adding MgF with the mass percentage content of 1 wt% to the powder sieved in the step (3)2Mixing, putting the mixed powder into a polyester ball milling tank, wherein the mass ratio of the raw materials to deionized water and zirconia balls is 1:30:15, and carrying out ball milling on a planetary ball mill for 12 hours at the ball milling rotating speed of 400/rpm;
(5) putting the raw materials subjected to ball milling in the step (4) into a drying oven, drying for 4 hours at 120 ℃, and then sieving by a 40-mesh sieve;
(6) adding 8 mass percent of paraffin wax as an adhesive into the powder sieved in the step (5) for granulation, and sieving the powder with a 80-mesh sieve;
(7) pressing the powder material obtained in the step (6) into a green body by using a powder tablet press under the pressure of 2 MPa;
(8) sintering the green body obtained in the step (7) at 1120 ℃, and preserving heat for 4 hours to obtain the lithium titanate-based microwave dielectric ceramic material;
(9) the microwave dielectric properties of the articles obtained in this example were tested by a network analyzer.
Example 3
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the pre-sintering time in the step (3) is 950 ℃, and the temperature is kept for 6 hours; MgF with the mass percent of 1.5 wt% is added in the step (4)2Mixing; the sintering temperature in the step (8) is 1120 ℃, and the temperature is kept for 6 hours; the rest of the process conditions were the same as in example 2.
Example 4
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 4 hours; MgF with the mass percent of 2 wt% is added in the step (4)2Mixing; the sintering temperature in the step (8) is 1120 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
Example 5
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 4 hours; MgF with the mass percent of 3 wt% is added in the step (4)2Mixing; the sintering temperature in the step (8) is 1100 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
Example 6
Preparing the lithium titanate-based microwave dielectric ceramic material and testing the microwave dielectric property of the obtained product according to the method of the embodiment 2, wherein the pre-sintering time in the step (3) is 800 ℃, and the temperature is kept6 hours; in the step (4), MgO with the mass percentage of 0.6469 wt% and MgF with the mass percentage of 0.8327 wt% are added in the step (4)2Mixing; (ii) a The sintering temperature in the step (8) is 1160 ℃, and the temperature is kept for 6 hours; the rest of the process conditions were the same as in example 2.
Example 7
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the pre-sintering time in the step (3) is 950 ℃, and the temperature is kept for 4 hours; in the step (4), the MgO with the mass percentage of 0.9704 wt% and the MgF with the mass percentage of 1.2491 wt% are added in the step (4)2Mixing; (ii) a The sintering temperature in the step (8) is 1140 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
Example 8
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 4 hours; in the step (4), the MgO with the mass percentage of 1.2938 wt% and the MgF with the mass percentage of 1.6654 wt% are added in the step (4)2Mixing; the sintering temperature in the step (8) is 1160 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
Example 9
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 4 hours; in the step (4), the MgO with the mass percentage of 1.9408 wt% and the MgF with the mass percentage of 2.4981 wt% are added in the step (4)2Mixing; (ii) a The sintering temperature in the step (8) is 1180 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
Example 10
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of example 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 6 hours; adding 0.8327 wt% LiF in the step (4) and mixing; the sintering temperature in the step (8) is 1180 ℃, and the temperature is kept for 6 hours; the rest of the process conditions were the same as in example 2.
Example 11
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 850 ℃, and the heat preservation is carried out for 8 hours; adding 1.2491 wt% LiF in the step (4) and mixing; the sintering temperature in the step (8) is 1160 ℃, and the temperature is kept for 8 hours; the rest of the process conditions were the same as in example 2.
Example 12
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of example 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 6 hours; adding 1.6654 wt% LiF in percentage by mass in the step (4) for mixing, wherein the ball milling time is 6 hours; the sintering temperature in the step (8) is 1180 ℃, and the temperature is kept for 6 hours; the rest of the process conditions were the same as in example 2.
Example 13
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 950 ℃, and the temperature is kept for 4 hours; adding 2.4981 wt% LiF in the step (4) and mixing; the sintering temperature in the step (8) is 1160 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
Example 14
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 850 ℃, and the temperature is kept for 2 hours; adding MgO with the mass percentage content of 0.6469 wt% in the step (4) for mixing; the sintering temperature in the step (8) is 1120 ℃, and the temperature is kept for 2 hours; the rest of the process conditions were the same as in example 2.
Example 15
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of example 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 1000 ℃, and the temperature is kept for 6 hours; adding 0.9704 wt% MgO in the step (4) and mixing, wherein the ball milling time is 6 hours; the sintering temperature in the step (8) is 1100 ℃, and the temperature is kept for 6 hours; the rest of the process conditions were the same as in example 2.
Example 16
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of example 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 4 hours; adding 1.2938 wt% MgO in the step (4) and mixing; the sintering temperature in the step (8) is 1120 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
Example 17
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 950 ℃, and the temperature is kept for 4 hours; adding 1.9408 wt% MgO in the step (4) and mixing; the sintering temperature in the step (8) is 1140 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
Example 18
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of example 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 2 hours; in the step (4), 1.1860 wt% of Li is added2CO3Mixing; the sintering temperature in the step (8) is 1100 ℃, and the temperature is kept for 2 hours; the rest of the process conditions were the same as in example 2.
Example 19
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of example 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 4 hours; in the step (4), 1.7790 wt% of Li is added2CO3Mixing; sintering in step (8)Keeping the temperature at 1120 ℃ for 4 hours; the rest of the process conditions were the same as in example 2.
Example 20
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of example 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 900 ℃, and the temperature is kept for 4 hours; in the step (4), 2.3720 wt% of Li is added2CO3Mixing, and ball milling for 6 hours; the sintering temperature in the step (8) is 1140 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
Example 21
Preparing a lithium titanate-based microwave dielectric ceramic material according to the method of the embodiment 2 and testing the microwave dielectric property of the obtained product, wherein the difference is that the pre-sintering time in the step (3) is 850 ℃, and the temperature is kept for 4 hours; in the step (4), 3.5581 wt% of Li is added2CO3Mixing; the sintering temperature in the step (8) is 1120 ℃, and the temperature is kept for 4 hours; the rest of the process conditions were the same as in example 2.
The results of the microwave dielectric property tests of examples 1-21 are detailed in Table 1
TABLE 1
Therefore, the invention can prepare the lithium titanate-based microwave dielectric ceramic material with higher Qf value (>100,000 GHz).
Although the preferred embodiments of the present invention have been described, the present invention is not limited to the above-mentioned embodiments, which are only illustrative and not restrictive, and those skilled in the art can make various modifications without departing from the spirit and scope of the present invention, which falls within the protection scope of the present invention.