Metatitanate ceramic having high temperature stability and method for producing the same

Abstract

The application discloses a metatitanate ceramic with high temperature stability and a preparation method thereof, and belongs to the field of microwave electronic ceramic materials.The chemical composition of the metatitanate ceramic is (Mg 1 / 2Zn 1 / 2 ) 0.4+x (Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) 0.6‑x TiO3, wherein 0<=x<0.6; the preparation method comprises the steps of weighing, primary ball milling, pre-sintering, secondary ball milling, granulation, primary sintering, secondary sintering and the like; and the application regulates the resonance frequency temperature coefficient of the ceramic through high entropy, optimizes the five kinds of ceramics with tau f all about-50 ppm / degree Celsius in the separate case to-17 ppm / degree Celsius through the high entropy effect without adding positive tau f materials, meanwhile, epsilon r =19.74, Qf=11500 GHz, and the application provides a new idea for the regulation of tau f .

Description

Technical Field

[0001] The present invention relates to the field of microwave electronic ceramic materials, and in particular to a metatitanate ceramic with high temperature stability and a preparation method thereof. Background Art

[0002] With the innovation of the new generation of wireless communication network technology, the environment in which electronic components are used has become more complex, which has put forward higher requirements on the stability of microwave components. f ), an important indicator of the temperature stability of microwave dielectric ceramics. The closer its absolute value is to 0, the better the temperature stability of the ceramic. Therefore, the demand for microwave dielectric ceramics with a resonant frequency temperature coefficient approaching zero in the field of communication equipment is becoming increasingly urgent.

[0003] In order to improve the temperature stability of ceramics, many scholars have f The material is used as a resonant frequency temperature coefficient compensator. Two-phase composite is a common method to improve the ceramic τ with temperature coefficient compensation. f Method, τ of 0.96MgTiO3-0.04CaTiO3 composite ceramics f The value is -2 ppm / ℃, but the Qf value is 26 100 GHz, and the different crystal structures of MgTiO3 and CaTiO3 cause them to coexist as different phases, which may cause changes in the dielectric properties of the composite material.

[0004] Multilayer co-firing is also commonly used to improve the positive temperature coefficient compensation τ f Methods such as Yue et al. prepared MgTiO3 / Li2TiO3 / MgTiO3 ceramics by multilayer co-firing. f The value is -3 ppm / ℃. This method of laminating and sintering two materials can make up for the shortcomings of the traditional mixed sintering method in producing other crystal phases. However, it requires good sintering compatibility between the two materials, and the actual production process is also more complicated than the traditional mixture.

[0005] Ion substitution is a commonly used method to improve the performance of microwave dielectric ceramics. Although most ion substitutions optimize the quality factor of ceramics, for example, Xu et al. used Ce 2+ Substitute Ca in the A position 2+ and use W 6+ Substitute Nb in the B position 5+ , optimizes the resonant frequency temperature coefficient, (Ce 0.85 Ca 0.15 )(Nb 0.85 W 0.15 )O4ε r = 19.7, Qf = 35,450 GHz,τ f= 0.8 ppm / ℃; however, due to the scarcity and high price of Ce and Nb metal reserves, it is difficult to widely use them in engineering practice.

[0006] Titanates have attracted widespread attention due to their superior properties. As a member of the MgO-TiO2 system, MgTiO3 has good dielectric properties: ε r =17, Qf = 160 000 GHz, the microwave dielectric ceramic device made of MgTiO3 as the matrix can reduce the dielectric loss of the microwave device, but it has a large negative resonant frequency temperature coefficient (τ f = -50 ppm / ℃), which limits its wide application in microwave communication systems. ZnTiO3 (τ f = -55 ppm / ℃), CoTiO3 (τ f = -53 ppm / ℃), NiTiO3 (τ f = -48 ppm / ℃), MnTiO3 (τ f = -64 ppm / ℃) also has a large negative resonant frequency temperature coefficient and a low Qf value.

[0007] Therefore, there is an urgent need in the art for a metatitanate ceramic with high temperature stability to meet the demand. Summary of the Invention

[0008] One of the objectives of the present invention is to provide a metatitanate ceramic with high temperature stability to solve the above problems.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows: a metatitanate ceramic with high temperature stability, the chemical composition of the metatitanate ceramic is: (Mg 1 / 2 Zn 1 / 2 ) 0.4+x (Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) 0.6-x TiO3, where 0≤x<0.6.

[0010] The microwave dielectric ceramics have a sintering temperature of 1000-1300°C, a resonant frequency temperature coefficient of -17ppm / °C, a dielectric constant between 16.5 and 20, and a Qf value of up to 58,700 GHz. They have broad application prospects in the next generation of wireless mobile communications and microwave communications.

[0011] As a preferred technical solution, x = 0. When x = 0 and the sintering temperature is 1200 ° C, the dielectric properties of the obtained microwave dielectric material are better, which is: τ f= -17 ppm / ℃, Qf = 11 500 GHz, ε r = 19.74.

[0012] A second object of the present invention is to provide a method for preparing the above-mentioned metatitanate ceramic with high temperature stability, comprising the following steps:

[0013] (1) Weighing materials and primary ball milling: Use at least four of MgO, ZnO, CoCO3, NiCO3, MnCO3 and TiO2 as raw materials, according to (Mg 1 / 2 Zn 1 / 2 ) 0.4+x (Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) 0.6-x TiO3, 0≤x<0.6, the ratio of the raw materials is weighed, and then ball milled and dried to obtain a dried material;

[0014] (2) Pre-burning: compact the dried material obtained in step (1), and then heat it to 800-1100 °C at a heating rate of 3-6 °C / min, then keep the material warm for 2-6 h, and then cool it to room temperature in the furnace to obtain a pre-burned material;

[0015] (3) Secondary ball milling: the pre-burned material obtained in step (2) is placed in a ball milling tank and subjected to secondary ball milling to obtain a slurry;

[0016] (4) Granulation: The slurry obtained in step (3) is dried to a constant weight, granulated, and pressed into samples;

[0017] (5) Primary sintering: Place the sample obtained in step (4) in a sintering furnace, heat it to 400-600 °C at a heating rate of 3-6 °C / min and keep it at that temperature for 2-6 h, and finally cool it to room temperature in the furnace to obtain a green sample after debinding;

[0018] (6) Secondary sintering: Place the green sample obtained in step (5) in a sintering furnace, raise the temperature to 1000-1300 °C at a heating rate of 3-6 °C / min, and keep it at that temperature for 2-6 h. Finally, cool it to room temperature in the furnace.

[0019] As a preferred technical solution, in both step (1) and step (3), zirconia balls are used as grinding balls and deionized water is used as the ball milling medium.

[0020] As a preferred technical solution, in step (4), 20 wt% PVA solution is added as a binder during granulation; the concentration of the PVA solution is 8~10 wt%.

[0021] As a preferred technical solution, the pressure during tableting after granulation in step (4) is 20 MPa, and the size of the pressed cylindrical sample is: diameter 12 mm × thickness 4~6 mm.

[0022] The present invention is based on (Mg 1 / 2 Zn 1 / 2 ) 0.4+x (Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) 0.6-x The value of x in TiO3, when x=0, the main phase component is MTiO3 (M is Mg, Zn, Co, Ni and Mn), when x≥0.1, the main phase components are MTiO3 and MTi2O5. Through the high entropy effect, τ is obtained f =-17 ppm / ℃ high entropy metatitanate microwave dielectric ceramics. The microwave dielectric material provided by the present invention, without adding a material with a positive temperature coefficient, reduces τ f The material with a value of around -50 ppm / ℃ has been significantly improved to -17 ppm / ℃.

[0023] Compared with the prior art, the advantages of the present invention are: the present invention regulates the resonant frequency temperature coefficient of the ceramic by high entropy, and changes the temperature coefficient of the resonant frequency of the ceramic to the temperature coefficient of the resonant frequency of the ceramic. f The five ceramics are all around -50 ppm / ℃. Through the high entropy effect, without adding positive τ f In the case of materials, it was optimized to -17 ppm / ℃, and ε r = 19.74, Qf = 11 500 GHz, the present invention is τ f It provides new ideas for regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 X-ray diffraction (XRD) pattern of the sample with x = 0 sintered at 1200 °C;

[0025] Figure 2 (Mg 1 / 2 Zn 1 / 2 ) 0.4+x (Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) 0.6-x Dielectric properties of TiO3 samples with x=0.0~0.6 sintered at 1200 ℃.

[0026] Figure 3 The dielectric properties of the sample with x = 0 sintered at 1000 ℃~1300 ℃.

[0027] Figure 4 This is the temperature coefficient diagram of the resonant frequency of the titanate sample sintered at 1200 ℃ when the configuration entropy ranges from 0 to 1.609R. DETAILED DESCRIPTION

[0028] The present invention is described below with reference to embodiments and further described in detail with reference to the accompanying drawings, but is not limited to the embodiments.

[0029] Example 1:

[0030] A metatitanate ceramic with high temperature stability, the preparation process of which is as follows:

[0031] Step 1: Follow (Mg 1 / 2 Zn 1 / 2 ) 0.4+x (Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) 0.6-x Weigh and prepare the raw materials in a ratio of TiO3 (x = 0.0-0.6); place the prepared raw materials in a ball mill filled with zirconium balls, use deionized water as the ball milling medium, set the ball mill speed to 250 rpm, and set the ball milling time to 4 hours. After the ball milling is completed, place the slurry in a constant temperature drying oven and dry it to constant weight for later use;

[0032] Step 2: The agglomerated powders after drying in step 1 were crushed in a mortar, placed in a crucible and compacted, and pre-sintered at a heating rate of 5°C / min to 100°C, then at a heating rate of 10°C / min to 1000°C; the material was then kept warm for 4 h, then cooled to 500°C at a rate of 5°C / min, and then cooled to room temperature with the furnace to obtain the pre-sintered material, which was placed in a ball mill for secondary ball milling and mixing;

[0033] Step 3: The powder obtained in step 2 was added with 20 wt% PVA solution as a binder, granulated, and uniaxially dry-pressed at 20 MPa into cylinders of 12 mm (diameter) × 6 mm (thickness);

[0034] Step 4: Place the green sample obtained in step 3 into a high-temperature sintering furnace, increase the temperature to 100°C at a heating rate of 5°C / min, then increase the temperature to 600°C at a heating rate of 10°C / min and keep it at that temperature for 4 h. Finally, reduce the temperature to 500°C at a heating rate of 5°C / min and cool it to room temperature in the furnace to obtain the green sample after debinding.

[0035] Step 5: Place the green sample after debinding in step 4 back into the high-temperature sintering furnace, and heat it to 100 °C at a rate of 5 °C / min, then to 1000 °C at a rate of 10 °C / min, and then to 1200 °C at a rate of 5 °C / min for sintering, and keep it at that temperature for 4 h. After the heat preservation is completed, reduce the temperature to 500 °C at a rate of 5 °C / min and cool it to room temperature in the furnace to obtain τ f Significantly improved high-entropy metatitanate microwave dielectric materials;

[0036] Figure 1 is the XRD pattern of the sample when x = 0. Figure 1 It can be seen that the sample prepared when x = 0 is a single phase;

[0037] Different x values ​​(Mg 1 / 2 Zn 1 / 2 ) 0.4+x (Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) 0.6-x Phase composition and microwave dielectric properties of TiO3 Figure 2 As shown. Figure 2 As can be seen from the figure, as x increases, the entropy of the ceramic decreases, τ f As the entropy value decreases, τ f = -17~-60ppm / ℃, when x = 0, τ f = -17 ppm / ℃, Qf = 11 500 GHz, ε r = 19.74.

[0038] Example 2:

[0039] A metatitanate ceramic with high temperature stability, the preparation process of which is as follows:

[0040] Step 1: Follow (Mg 0.2 Zn 0.2 Co 0.2 Ni 0.2 Mn 0.2 )TiO3 in a certain proportion to weigh and prepare the raw materials; the prepared raw materials were placed in a ball mill jar filled with zirconium balls, deionized water was used as the ball milling medium, the ball mill speed was set to 250rpm, the ball milling time was set to 4h, and after the ball milling was completed, the slurry was placed in a constant temperature drying oven and dried to constant weight for use.

[0041] Step 2: The agglomerated powders after drying in step 1 were crushed in a mortar, placed in a crucible and compacted, and pre-sintered at a heating rate of 5°C / min to 100°C, then at a heating rate of 10°C / min to 1000°C; the material was then kept warm for 4 h, then cooled to 500°C at a rate of 5°C / min, and then cooled to room temperature with the furnace to obtain the pre-sintered material, which was placed in a ball mill for secondary ball milling and mixing;

[0042] Step 3: The powder obtained in step 2 was added with 20 wt% PVA solution as a binder, granulated, and uniaxially dry-pressed at 20 MPa into cylinders of 12 mm (diameter) × 6 mm (thickness);

[0043] Step 4: Place the green sample obtained in step 3 into a high-temperature sintering furnace, increase the temperature to 100°C at a heating rate of 5°C / min, then increase the temperature to 600°C at a heating rate of 10°C / min and keep it at that temperature for 4 h. Finally, reduce the temperature to 500°C at a heating rate of 5°C / min and cool it to room temperature in the furnace to obtain the green sample after debinding.

[0044] Step 5: Place the green sample after debinding in step 4 into the high-temperature sintering furnace again, and heat it to 100 °C at a rate of 5 °C / min, and then heat it to 1000 °C at a rate of 10 °C / min. Sinter one of them at 1000 °C, and heat the remaining three to 1100 °C, 1200 °C, and 1300 °C at a rate of 5 °C / min, respectively, and keep them warm for 4 h. After the end of the heat preservation, reduce the temperature to 500 °C at a rate of 5 °C / min and then cool it to room temperature in the furnace to obtain τ f Significantly improved high-entropy metatitanate microwave dielectric materials;

[0045] (Mg at different sintering temperatures 0.2 Zn 0.2 Co 0.2 Ni 0.2 Mn 0.2 ) Phase composition and microwave dielectric properties of TiO3 Figure 3 When the sintering temperature is 1000℃, the ceramic reaches the densification temperature, which makes the parameters abnormal. When the sintering temperature is 1100℃~1300℃, τ f Between -31 ppm / ℃ and -17 ppm / ℃, Qf between 10 600 GHz and 12 000 GHz, ε r Between 19.28 and 19.74, when the sintering temperature is 1200 ℃, τ f = -17 ppm / ℃, Qf = 11 500 GHz, ε r = 19.74.

[0046] Example 3:

[0047] A metatitanate ceramic with high temperature stability, the preparation process of which is as follows:

[0048] Step 1: According to MgTiO3, (Mg 0.5 Zn 0.5 )TiO3, (Mg 1 / 3 Zn 1 / 3 B 1 / 3 )TiO3(B = Co, Ni and Mn) and (Mg 0.25 Zn 0.25 Ni 0.25 Mn 0.25 )TiO3 ratio to weigh and prepare the raw materials; the prepared raw materials were placed in a ball mill jar filled with zirconium balls, deionized water was used as the ball milling medium, the ball mill speed was set to 250 rpm, the ball milling time was set to 4h, and after the ball milling was completed, the slurry was placed in a constant temperature drying oven and dried to constant weight for use.

[0049] Step 2: The agglomerated powders after drying in step 1 were crushed in a mortar, placed in a crucible and compacted, and pre-sintered at a heating rate of 5°C / min to 100°C, then at a heating rate of 10°C / min to 1000°C; the material was then kept warm for 4 h, then cooled to 500°C at a rate of 5°C / min, and then cooled to room temperature with the furnace to obtain the pre-sintered material, which was placed in a ball mill for secondary ball milling and mixing;

[0050] Step 3: The powder obtained in step 2 was added with 20 wt% PVA solution as a binder, granulated, and uniaxially dry-pressed at 20 MPa into cylinders of 12 mm (diameter) × 6 mm (thickness);

[0051] Step 4: Place the green sample obtained in step 3 into a high-temperature sintering furnace, increase the temperature to 100°C at a heating rate of 5°C / min, then increase the temperature to 600°C at a heating rate of 10°C / min and keep it at that temperature for 4 h. Finally, reduce the temperature to 500°C at a heating rate of 5°C / min and cool it to room temperature in the furnace to obtain the green sample after debinding.

[0052] Step 5: Place the green sample after debinding in step 4 back into the high-temperature sintering furnace, and heat it to 100 °C at a rate of 5 °C / min, then to 1000 °C at a rate of 10 °C / min, and then to 1200 °C at a rate of 5 °C / min for sintering, and keep it at that temperature for 4 h. After the heat preservation is completed, reduce the temperature to 500 °C at a rate of 5 °C / min and cool it to room temperature in the furnace to obtain τ f Significantly improved titanate microwave dielectric materials.

[0053] The resonant frequency temperature coefficients of metatitanates with different compositions are as follows: Figure 4 As shown in the figure, it can be seen that as the number of elements at the A position of the metatitanate increases, the configuration entropy of the ceramic also increases. f It shows a trend closer to 0. When the A position is 4-membered, that is, when the configuration entropy is 1.386R, τ f = -27ppm / ℃, when the A position is 5-membered, that is, when the configuration entropy is 1.609R, τ f = -17ppm / ℃.

[0054] In addition, during the research and development process, the inventors tried to use a 50:50 combination of six elements: Mg, Zn, Co, Ni, Cu, and Mn, but almost no peak was found when measuring Qf, proving that its dielectric properties were poor.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A metatitanate ceramic with high temperature stability, characterized in that: The chemical composition of the metatitanate ceramic is: (Mg 1 / 2 Zn 1 / 2 ) 0.4+x (Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) 0.6-x TiO3, where 0≤ x <0.

4.

2. The metatitanate ceramic with high temperature stability according to claim 1, characterized in that x =0。 3. The method for preparing metatitanate ceramics with high temperature stability according to claim 1 or 2, characterized in that: The steps include: (1) Weighing materials and primary ball milling: MgO, ZnO, CoCO3, NiCO3, MnCO3 and TiO2 are used as raw materials. 1 / 2Zn 1 / 2 ) 0.4+x (Co 1 / 3 Ni 1 / 3 Mn 1 / 3 ) 0.6-x TiO3, 0≤ x The raw materials are weighed and then ball-milled and dried to obtain dried materials; (2) Pre-burning: compact the dried material obtained in step (1), and then heat it to 800-1100 °C at a heating rate of 3-6 °C / min, then keep the material warm for 2-6 h, and then cool it to room temperature in the furnace to obtain a pre-burned material; (3) Secondary ball milling: the pre-burned material obtained in step (2) is placed in a ball milling tank and subjected to secondary ball milling to obtain a slurry; (4) Granulation: The slurry obtained in step (3) is dried to a constant weight, granulated, and pressed into samples; (5) Primary sintering: Place the sample obtained in step (4) in a sintering furnace, heat it to 400-600 °C at a heating rate of 3-6 °C / min and keep it at that temperature for 2-6 h, and finally cool it to room temperature in the furnace to obtain a green sample after debinding; (6) Secondary sintering: Place the green sample obtained in step (5) in a sintering furnace, raise the temperature to 1000-1300 °C at a heating rate of 3-6 °C / min, and keep it at that temperature for 2-6 h. Finally, cool it to room temperature in the furnace.

4. The preparation method according to claim 3, characterized in that In both steps (1) and (3), zirconia balls are used as grinding balls and deionized water is used as the ball milling medium.

5. The preparation method according to claim 3, characterized in that In step (4), 20 wt% PVA solution is added as a binder during granulation.

6. The preparation method according to claim 3, characterized in that The pressure during tableting after granulation in step (4) is 20 MPa, and the size of the pressed cylindrical sample is: diameter 12 mm × thickness 4~6 mm.

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