A preparation method of lithium titanate-based rock salt structure microwave dielectric ceramic material and the product obtained

Abstract

The present invention discloses a preparation method of a lithium titanate-based rock salt structure microwave dielectric ceramic material and the product obtained, using Li2CO3, TiO2, ZnO and MoO3 as raw materials, and (Zn 0.5 Mo 0.5 ) 4+ Replace Ti in Li2TiO3 4+ , forming a chemical formula of Li2Ti 1‑x (Zn 0.5 Mo 0.5 ) x O3 microwave dielectric ceramic materials effectively adjust the temperature-frequency characteristics and dielectric loss of microwave dielectric ceramics, thereby obtaining Li2Ti with excellent dielectric properties, including moderate dielectric constant, high Qf value and good resonant frequency temperature coefficient. 1‑x (Zn 0.5 Mo 0.5 ) x O3 microwave dielectric ceramic material has broad application prospects in the field of high-frequency communications.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave dielectric ceramic materials, and in particular to a preparation method of a lithium titanate-based microwave dielectric ceramic material and a product obtained therefrom. Background Art

[0002] Microwave dielectric ceramics are a new type of electronic material used as dielectric materials in microwave frequency circuits. They are widely used in microwave resonators, filters, dielectric substrates, and dielectric antennas. Their high relative permittivity (10-100), very low dielectric loss, and near-zero resonant frequency temperature coefficient make them crucial in microwave communication technology. In 5G mobile communication systems, microwave dielectric ceramic components are key components of the radio frequency units (RFUs) in communication base stations. With the development of the times and the development of 6G communications, higher and newer performance requirements for microwave dielectric ceramics are being placed.

[0003] Li2TiO3, a common microwave dielectric ceramic, has become an important material in modern microwave communication technology due to its excellent dielectric properties and low preparation cost. However, the optimal sintering temperature for synthesizing single-phase Li2TiO3 microwave dielectric ceramics using traditional solid-phase synthesis is 1300°C, at which εr = 19.46, Qf = 39,749 GHz, and TCF = 19.87 ppm / °C. Therefore, the low Qf value, large positive TCF value, and lithium volatilization caused by high sintering temperatures of existing Li2TiO3 ceramics are significant challenges. Existing research has shown that the synergistic replacement of Ti ions in different systems can effectively adjust the resonant frequency temperature coefficient and reduce dielectric loss. However, existing modifications of lithium titanate-based microwave dielectric ceramics still face problems such as excessively high dielectric loss and TCF values ​​that are insufficient for practical applications. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing a microwave dielectric ceramic material with a lithium titanate-based rock salt structure. 0.5 Mo 0.5 ) 4+ Replace Ti in Li2TiO3 4+ , in order to effectively adjust the temperature-frequency characteristics and dielectric loss of microwave dielectric ceramics, thereby obtaining Li2Ti with excellent dielectric properties, including moderate dielectric constant, high Qf value and good resonant frequency temperature coefficient. 1-x (Zn 0.5 Mo 0.5 ) x O3 microwave dielectric ceramic material has a wide range of application prospects in the field of high-frequency communications. Another object of the present invention is to provide a product made by the preparation method of the above-mentioned lithium titanate-based rock salt structure microwave dielectric ceramic material.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The present invention provides a method for preparing a lithium titanate-based rock salt structure microwave dielectric ceramic material, wherein the chemical formula of the microwave dielectric ceramic material is Li2Ti 1-x (Zn 0.5 Mo 0.5 ) x O3, wherein 0≤x≤0.3; the preparation method comprises the following steps:

[0007] (1) According to the chemical formula, Li2CO3, TiO2, ZnO, and MoO3 are weighed as raw materials, and ball milled with anhydrous ethanol as a medium to obtain a mixture;

[0008] (2) After drying the mixed material, heating it to 870-960° C. at a rate of 3° C. / min for pre-calcining, and keeping the temperature for 1-3 hours to obtain a pre-calcined material;

[0009] (3) subjecting the pre-sintered material to secondary ball milling, secondary drying, granulation and press molding to obtain a green body;

[0010] (4) The green body is subjected to a binder removal treatment, and then the temperature is raised to 1030-1225° C. at a rate of 3° C. / min for sintering, and the temperature is kept at this temperature for 2-4 hours. The green body is then cooled to 200° C. at a rate of 3° C. / min, and then naturally cooled to room temperature to obtain a microwave dielectric ceramic material.

[0011] Furthermore, in step (3) of the present invention, the PVA solution is added to the powder obtained after secondary drying, and the mixture is granulated to obtain granular powder with a particle size of 0.125 to 0.25 mm. The pressure of the pressing molding is 8 to 12 MPa, and the holding time is 1 to 3 minutes.

[0012] Furthermore, in step (4) of the present invention, the binder removal treatment is carried out by maintaining the temperature at 450-550° C. for 4-6 hours.

[0013] The product is made by the above-mentioned method for preparing the microwave dielectric ceramic material of lithium titanate-based rock salt structure, and the dielectric constant ε of the microwave dielectric ceramic material is r The value is 15.5~21.0, the Qf value is 17380~81460Ghz, and the TCF value is 33.3~-34.9ppm / ℃.

[0014] The present invention has the following beneficial effects:

[0015] (1) The present invention is achieved by 0.5 Mo 0.5 ) 4+Composite ions are doped into Li2TiO3 with an ionic radius of Zn 2+ and the ionic radius is Mo 6+ The composite ions (Zn 0.5 Mo 0.5 ) 4+ , the substitution ionic radius is Ti 4 + , forming Li2Ti 1-x (Zn 0.5 Mo 0.5 ) x O3 solid solution causes the unit cell to be distorted, changes the unit cell parameters, and transforms the crystal from a monoclinic structure to a cubic structure, thereby achieving the effect of regulating TCF. 0.5 Mo 0.5 ) 4+ The ions inhibit the formation of oxygen vacancies, which reduces the dielectric loss of lithium titanate-based microwave dielectric ceramic materials.

[0016] (2) The present invention is carried out by (Zn 0.5 Mo 0.5 ) 4+ The Ti ions in Li2TiO3 are subjected to composite replacement to improve the quality factor while adjusting the temperature coefficient of resonant frequency (TCF). When x = 0.09, the TCF is close to 0 and reaches 1.0ppm / ℃, and the Qf value reaches a maximum of 81460GHz. Therefore, the method of the present invention not only optimizes the Qf value of lithium titanate-based rock salt structure microwave dielectric ceramics, but also achieves a near-zero TCF value. The optimization of these performance indicators can effectively reduce signal transmission delay, increase the stability of microwave devices during operation, and improve the efficiency and reliability of signal transmission. Therefore, the microwave dielectric ceramic material of the present invention has important application value and economic significance in the fields of electronic circuit substrates, dielectric resonators, filters, high-frequency satellite microwave device substrates and microstrip lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be described in further detail below with reference to the embodiments and accompanying drawings:

[0018] Figure 1 is the dielectric constant of the microwave dielectric ceramic material prepared in the embodiment of the present invention;

[0019] Figure 2 is the Q×f value of the microwave dielectric ceramic material prepared in the embodiment of the present invention;

[0020] Figure 3 is the TCF value of the microwave dielectric ceramic material prepared in the embodiment of the present invention. DETAILED DESCRIPTION

[0021] Example 1:

[0022] This embodiment provides a method for preparing a microwave dielectric ceramic material with a lithium titanate-based rock salt structure. The chemical formula of the microwave dielectric ceramic material is Li2Ti 0.95 (Zn 0.5 Mo 0.5 ) 0.05 O3; the preparation method comprises the following steps:

[0023] (1) According to the above chemical formula, Li2CO3, TiO2, ZnO, and MoO3 were weighed as raw materials, respectively, and ball milled with anhydrous ethanol at a ball:material ratio of 2:1 for 4 h (at a speed of 350 rpm) to obtain a mixed material;

[0024] (2) After drying the mixed material, pre-calcining it at 915° C. for 2 hours to obtain a pre-calcined material;

[0025] (3) After the pre-sintered material is subjected to a secondary ball milling treatment and secondary drying, a 5% PVA solution is added to granulate the material to obtain a granular powder with a particle size of 0.125 to 0.25 mm, which is then pressed under a pressure of 10 MPa to obtain a green body;

[0026] (4) The green body was kept at 550°C for 4 h for debinding treatment, then heated to 1225°C at a rate of 3°C / min for sintering, kept at that temperature for 2 h, and then cooled to 200°C at a rate of 3°C / min, and then naturally cooled to room temperature to obtain a microwave dielectric ceramic material.

[0027] Example 2:

[0028] The method for preparing a microwave dielectric ceramic material with a lithium titanate-based rock salt structure in this embodiment differs from that in the first embodiment in that:

[0029] The chemical formula of microwave dielectric ceramic material is Li2Ti 0.91 (Zn 0.5 Mo 0.5 ) 0.09 O3.

[0030] The sintering temperature of step (4) is 1175°C.

[0031] Example 3:

[0032] The method for preparing a microwave dielectric ceramic material with a lithium titanate-based rock salt structure in this embodiment differs from that in the first embodiment in that:

[0033] The chemical formula of microwave dielectric ceramic material is Li2Ti 0.89 (Zn 0.5 Mo 0.5 )0.11 O3.

[0034] The sintering temperature of step (4) is 1175°C.

[0035] Example 4:

[0036] The method for preparing a microwave dielectric ceramic material with a lithium titanate-based rock salt structure in this embodiment differs from that in the first embodiment in that:

[0037] The chemical formula of microwave dielectric ceramic material is Li2Ti 0.8 (Zn 0.5 Mo 0.5 ) 0.2 O3.

[0038] The pre-firing temperature in step (2) is 870°C.

[0039] The sintering temperature of step (4) is 1040°C.

[0040] Embodiment 5:

[0041] The method for preparing a microwave dielectric ceramic material with a lithium titanate-based rock salt structure in this embodiment differs from that in the first embodiment in that:

[0042] The chemical formula of microwave dielectric ceramic material is Li2Ti 0.7 (Zn 0.5 Mo 0.5 ) 0.3 O3.

[0043] The pre-firing temperature in step (2) is 870°C.

[0044] The sintering temperature of step (4) is 1030°C.

[0045] Performance testing:

[0046] The dielectric properties of the lithium titanate-based rock salt structure microwave dielectric ceramic material prepared in the embodiment of the present invention were tested using an Agilent 8720B network analyzer and a metal closed cavity. The test results are shown in Table 1.

[0047] Table 1 Dielectric properties of microwave dielectric ceramic materials according to embodiments of the present invention

[0048]

[0049] The microwave dielectric ceramic material prepared in the embodiment of the present invention is as follows Figure 1 As shown, its dielectric constant ε r As the value of x increases, it decreases. Figure 2 、 Figure 3As shown, when x=0.09, TCF is close to 0 and reaches 1.0ppm / ℃, and the Qf value reaches up to 81460GHz. Therefore, the method of the present invention not only optimizes the Qf value of lithium titanate-based rock salt structure microwave dielectric ceramics, but also achieves a TCF value close to zero.

Claims

1. A method for preparing a lithium titanate-based rock salt structure microwave dielectric ceramic material, characterized by: The chemical formula of the microwave dielectric ceramic material is Li2Ti 1-x (Zn 0.5 Mo 0.5 ) x O3, wherein 0<x≤0.3; the preparation method comprises the following steps: (1) According to the chemical formula, Li2CO3, TiO2, ZnO, and MoO3 are weighed as raw materials, and ball milled with anhydrous ethanol as a medium to obtain a mixture; (2) After drying the mixed material, heating it to 870-960° C. at a rate of 3° C. / min for pre-calcining, and keeping the temperature for 1-3 hours to obtain a pre-calcined material; (3) performing secondary ball milling, secondary drying, granulation and press molding on the pre-sintered material to obtain a green body; (4) The green body is subjected to a binder removal treatment, and then the temperature is increased to 1030-1225° C. at a rate of 3° C. / min for sintering, and the temperature is kept at this temperature for 2-4 hours. The green body is then cooled to 200° C. at a rate of 3° C. / min, and then naturally cooled to room temperature to obtain a microwave dielectric ceramic material.

2. The method for preparing the lithium titanate-based rock salt structure microwave dielectric ceramic material according to claim 1, characterized in that: In the step (3), PVA solution is added to the powder obtained after secondary drying and mixed and granulated to obtain granular powder with a particle size of 0.125 to 0.25 mm.

3. The method for preparing the lithium titanate-based rock salt structure microwave dielectric ceramic material according to claim 1, characterized in that: The pressure of the compression molding in the step (3) is 8 to 12 MPa, and the holding time is 1 to 3 minutes.

4. The method for preparing the lithium titanate-based rock salt structure microwave dielectric ceramic material according to claim 1, characterized in that: In the step (4), the debinding treatment is carried out by maintaining the temperature at 450-550° C. for 4-6 hours.

5. A product produced by the method for producing a lithium titanate-based rock salt structure microwave dielectric ceramic material according to any one of claims 1 to 4, characterized in that: The dielectric constant ε of the microwave dielectric ceramic material r The value is 15.5~21.0, the Qf value is 17380~81460Ghz, and the TCF value is 33.3~-34.9ppm / ℃.

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