A high-entropy silicate microwave dielectric material with temperature stability achieved through regulation of oxygen octahedron distortion and its preparation method

Abstract

The present invention discloses a high entropy silicate microwave dielectric material and a preparation method thereof that realizes temperature stability based on the regulation of oxygen octahedron distortion, belonging to the field of microwave electronic ceramic materials. The chemical composition of the material is: Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 )SiO4, the sintering temperature during preparation is 1060-1140℃; the near-zero τ provided by the present invention f τ of microwave dielectric materials f =-1.28ppm / ℃, ε r =9.1~9.8, Q×f=15 700~20 100GHz; τ near zero f The value can improve the stability of the manufactured microwave components and can be widely used in the new generation of wireless mobile communications and microwave communications.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave electronic ceramic materials, and in particular to a high-entropy silicate microwave dielectric material that achieves temperature stability based on oxygen octahedron distortion regulation and a preparation method thereof. Background Art

[0002] With the innovation of the new generation of wireless communication network technology, higher requirements are placed on the miniaturization and high stability of microwave components. Due to the main features of low latency (time delay), large bandwidth and high-speed data transmission of 5G technology, it has a low dielectric constant (ε r ) and new microwave dielectric materials with high quality factor (Q×f) need to be further explored. More importantly, the resonant frequency temperature coefficient (τ f ) is very important to ensure the operation stability of the equipment. Silicate is known for its high Q×f value and low ε r Most silicates have τ values ​​due to structural problems. f The value is relatively poor, which greatly limits the application of silicates in practice. Taking Mg2SiO4 with olivine structure as an example, the Q×f value of Mg2SiO4 can be as high as 240000GHz, while its poor τ f The value (-67ppm / ℃) has greatly limited its practical application. Therefore, how to improve the τ f Value is a pressing issue.

[0003] In 2004, Yeh et al. proposed the concept of high entropy alloys, which have many new advantages compared to traditional alloys. As high entropy alloy technology matures, the concept of high entropy has gradually been applied to other fields, such as high entropy ceramics. In 2015, Rost et al. prepared high entropy rock salt oxide ceramics and successfully applied high entropy to the field of ceramics. High entropy has a good improvement on the performance of various aspects of ceramics. Therefore, how to use high entropy to improve the τ of silicates? f It is worth people's exploration.

[0004] For materials with olivine structure, its τ f The value is usually affected by the presence of oxygen octahedrons in the structure. In recent years, more and more studies have used high entropy to control the distortion of oxygen octahedrons to improve τ. f For example, Liu et al. prepared high entropy silicates (Mg 0.2 Ni 0.2 Zn 0.2 Co 0.2 Mn 0.2 )2SiO4, its τ f The value is -38.2ppm / ℃, and the oxygen octahedron distortion is 1.8×10-3 , which improves the τ of Mg2SiO4 to a certain extent f value. But its τ f There is still much room for improvement. Summary of the Invention

[0005] One of the objectives of the present invention is to provide a high entropy silicate microwave dielectric material that achieves temperature stability based on the regulation of oxygen octahedron distortion to solve the above problems.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a high entropy silicate microwave dielectric material based on the regulation of oxygen octahedron distortion to achieve temperature stability, the chemical composition of the material is: Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 )SiO4, the sintering temperature during preparation is 1060~1140℃.

[0007] As a preferred technical solution, the sintering temperature during preparation is 1060-1100°C.

[0008] The present invention improves its τ by regulating the distortion of oxygen octahedron f value, the smaller the oxygen octahedron distortion, τ f The closer the value is to zero.

[0009] A second object of the present invention is to provide a method for preparing the high-entropy silicate microwave dielectric material based on the above-mentioned regulation of oxygen octahedral distortion to achieve temperature stability, comprising the following steps:

[0010] (1) Yb2O3, Ho2O3, Tm2O3, In2O3, Y2O3 and Li2CO3 are used as raw materials. 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 ) SiO4 stoichiometric ratio is weighed, and then the weighed raw materials are mixed and ball milled once, and the materials are dried to obtain a dried material;

[0011] (2) The dried material obtained in step (1) was placed in an alumina crucible and compacted, and the temperature was raised to 1000°C at a rate of 3-6°C / min, and then kept at this temperature for 2-6 hours, and then cooled to room temperature with the furnace to obtain Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 )SiO4 calcined material;

[0012] (3) Li(Yb) obtained in step (2) 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 ) The SiO4 pre-calcined material is placed in a ball mill and subjected to secondary ball milling to obtain a slurry;

[0013] (4) drying the slurry obtained in step (3) to constant weight, granulating the slurry, and pressing the slurry into samples;

[0014] (5) placing the sample obtained in step (4) in a high-temperature sintering furnace, heating the temperature to 400-600°C at a heating rate of 3-6°C / min and keeping the temperature for 2-6 hours, and finally cooling the sample to room temperature to obtain a green sample after debinding;

[0015] (6) The green sample obtained in step (5) is placed in a high-temperature sintering furnace, heated to 1060-1140°C at a heating rate of 3-6°C / min, and kept warm for 2-6 hours. Finally, the green sample is cooled to room temperature in the furnace to obtain a high entropy silicate microwave dielectric material with a resonant frequency temperature coefficient of near zero.

[0016] 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.

[0017] As a preferred technical solution, in step (4), 20 wt% PVA solution is added as a binder during granulation.

[0018] As a preferred technical solution, in step (4), the pressing pressure is 20 MPa, and the size of the pressed cylindrical sample is: diameter 12 mm × thickness 4 to 6 mm.

[0019] The main phase components of the microwave dielectric material of the present invention are LiTmSiO4 and LiY9(SiO4)6O2, and the near-zero τ f The microwave dielectric material presented by the present invention has a near-zero τ f value (-1.28ppm / ℃).

[0020] Compared with the prior art, the advantages of the present invention are: f = +23.3ppm / ℃) and improves the system by controlling the oxygen octahedral distortion through a high entropy strategy to achieve a near-zero τ f value, and does not cause significant deterioration in other microwave dielectric properties and sintering temperature. The near-zero τ f Microwave dielectric materials: Li(Yb 0.2 Ho 0.2 Tm0.2 In 0.2 Y 0.2 )SiO4, its sintering temperature is 1060~1140℃, τ f =-1.28ppm / ℃, ε r =9.1~9.8, Q×f=15 700~20 100GHz; τ near zero f The value can improve the stability of the manufactured microwave components and can be widely used in the new generation of wireless mobile communications and microwave communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the X-ray diffraction (XRD) pattern of the sample sintered at 1060-1140°C;

[0022] Figure 2 The microwave dielectric properties of the samples sintered at 1060-1140℃ are shown;

[0023] Figure 3 Li(Yb) 0.25 Ho 0.25 Tm 0.25 Y 0.25 ) X-ray diffraction (XRD) pattern of SiO4 sintered at 1040-1080°C;

[0024] Figure 4 Li(Yb) 0.25 Ho 0.25 Tm 0.25 Y 0.25 )Microwave dielectric properties of SiO4 sintered at 1040-1080℃. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the embodiments.

[0026] Example 1:

[0027] A high-entropy silicate microwave dielectric material that regulates oxygen octahedron distortion based on high entropy effect to achieve a near-zero resonant frequency temperature coefficient, and a specific preparation method thereof is as follows:

[0028] Step 1: According to Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2) SiO4 stoichiometric ratio of the raw materials were weighed and configured; the prepared raw materials were placed in a ball mill jar containing 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, after the ball milling was completed, the slurry was placed in a constant temperature drying oven and dried to constant weight for standby use;

[0029] Step 2: The powders agglomerated after drying in step 1 were crushed in a mortar, placed in a crucible and compacted, and then heated to 100°C at a rate of 5°C / min, then heated to 1000°C at a rate of 10°C / min for pre-sintering, then kept at this temperature for 4 hours, and then cooled to 500°C at a rate of 5°C / min and cooled to room temperature with the furnace to obtain Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 ) SiO4 pre-calcined material, and then put the pre-calcined material into a ball mill jar for secondary ball milling and mixing;

[0030] Step 3: Add 20 wt% PVA solution as a binder to the powder obtained in step 2, granulate, and uniaxially dry-press into cylinders of 12 mm (diameter) × 6 mm (thickness) at 20 MPa;

[0031] Step 4: Place the green sample obtained in step 3 into a high-temperature sintering furnace, increase the temperature to 100°C at a rate of 5°C / min, then increase the temperature to 600°C at a rate of 10°C / min and keep it at that temperature for 4 hours, and finally reduce the temperature to 500°C at a rate of 5°C / min and cool it to room temperature in the furnace to obtain a green sample after debinding;

[0032] 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, then to 1000°C at a rate of 10°C / min, and then to 1060°C at a rate of 5°C / min for sintering, and keep it warm for 4 hours. After the end of the heat preservation, cool it to 500°C at a rate of 5°C / min and then cool it to room temperature with the furnace to obtain a near-zero τ f High entropy silicate microwave dielectric materials with high values;

[0033] Figure 1 The XRD patterns of the samples at different sintering temperatures are shown in Figure 2. Figure 1 It can be seen that when the sintering temperature is 1060℃, the sample contains LiTmSiO4 and LiY9(SiO4)6O2 phases;

[0034] Li(Yb) 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 )SiO4 microwave dielectric properties such as Figure 2 As shown in the figure, when the sintering temperature is 1060℃, τ f =-1.28ppm / ℃, Q×f=20 100GHz, ε r =9.4, oxygen octahedron distortion is 2.50×10 -4 .

[0035] Example 2:

[0036] A high-entropy silicate microwave dielectric material that regulates oxygen octahedron distortion based on high entropy effect to achieve a near-zero resonant frequency temperature coefficient, and a specific preparation method thereof is as follows:

[0037] Step 1: According to Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 ) SiO4 stoichiometric ratio of the raw materials were weighed and configured; the prepared raw materials were placed in a ball mill jar containing 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, after the ball milling was completed, the slurry was placed in a constant temperature drying oven and dried to constant weight for standby use;

[0038] Step 2: The powders agglomerated after drying in step 1 were crushed in a mortar, placed in a crucible and compacted, and then heated to 100°C at a rate of 5°C / min, then heated to 1000°C at a rate of 10°C / min for pre-sintering, then kept at this temperature for 4 hours, and then cooled to 500°C at a rate of 5°C / min and cooled to room temperature with the furnace to obtain Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 ) SiO4 pre-calcined material, and then put the pre-calcined material into a ball mill jar for secondary ball milling and mixing;

[0039] Step 3: Add 20 wt% PVA solution as a binder to the powder obtained in step 2, grind and granulate, and uniaxially dry-press into cylinders of 12 mm (diameter) × 6 mm (thickness) at 20 MPa;

[0040] Step 4: Place the green sample obtained in step 3 into a high-temperature sintering furnace, increase the temperature to 100°C at a rate of 5°C / min, then increase the temperature to 600°C at a rate of 10°C / min and keep it at that temperature for 4 hours, and finally reduce the temperature to 500°C at a rate of 5°C / min and cool it to room temperature in the furnace to obtain a green sample after debinding;

[0041] Step 5: Place the green sample after debinding in step 4 into the high-temperature sintering furnace again, and heat it to 100℃ at a rate of 5℃ / min, then to 1000℃ at a rate of 10℃ / min, and then to 1100℃ at a rate of 5℃ / min for sintering, and keep it at that temperature for 4h. After the end of the heat preservation, cool it to 500℃ at a rate of 5℃ / min and then cool it to room temperature with the furnace to obtain a near-zero τ f High entropy silicate microwave dielectric materials;

[0042] The phase composition of the sample sintered at 1100℃ is as follows Figure 1 As shown in the figure, it can be seen that the phase composition of the sample at this time is LiTmSiO4 phase and LiY9(SiO4)6O2 phase. Figure 2 It can be seen from the microwave dielectric properties of the sample at 1100℃, τ f =+1.26ppm / ℃,Q×f=18 300GHz,ε r =9.8, oxygen octahedron distortion is 2.45×10 -4 .

[0043] Comparative Example 1:

[0044] In order to illustrate that the present invention is based on the high entropy effect, τ f The value is close to zero, not due to the multiphase composite effect, the microwave dielectric material Li (Yb 0.25 Ho 0.25 Tm 0.25 Y 0.25 ) The specific preparation method, properties and phase composition of SiO4 are described as follows:

[0045] Step 1: According to Li(Yb 0.25 Ho 0.25 Tm 0.25 Y 0.25 ) SiO4 stoichiometric ratio of the raw materials were weighed and configured; the prepared raw materials were placed in a ball mill jar containing 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, after the ball milling was completed, the slurry was placed in a constant temperature drying oven and dried to constant weight for standby use;

[0046] Step 2: The powders agglomerated after drying in step 1 were crushed in a mortar, placed in a crucible and compacted, and then heated to 100°C at a rate of 5°C / min, then heated to 1000°C at a rate of 10°C / min for pre-sintering, then kept at this temperature for 4 hours, and then cooled to 500°C at a rate of 5°C / min and cooled to room temperature with the furnace to obtain Li(Yb 0.25 Ho 0.25 Tm 0.25 Y 0.25) SiO4 pre-calcined material, and then put the pre-calcined material into a ball mill jar for secondary ball milling and mixing;

[0047] Step 3: Add 20 wt% PVA solution as a binder to the powder obtained in step 2, grind and granulate, and uniaxially dry-press into cylinders of 12 mm (diameter) × 6 mm (thickness) at 20 MPa;

[0048] Step 4: Place the green sample obtained in step 3 into a high-temperature sintering furnace, increase the temperature to 100°C at a rate of 5°C / min, then increase the temperature to 600°C at a rate of 10°C / min and keep it at that temperature for 4 hours, and finally reduce the temperature to 500°C at a rate of 5°C / min and cool it to room temperature in the furnace to obtain a green sample after debinding;

[0049] 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, then heat it to 1000°C at a rate of 10°C / min, and then heat it to 1040-1080°C at a rate of 5°C / min for sintering, and keep it warm for 4 hours. After the end of the heat preservation, cool it to 500°C at a rate of 5°C / min and then cool it to room temperature with the furnace to obtain the silicate microwave dielectric material Li(Yb 0.25 Ho 0.25 Tm 0.25 Y 0.25 )SiO4;

[0050] The phase composition of the sample sintered at 1040-1080℃ is as follows Figure 3 As shown in the figure, Li(Yb 0.25 Ho 0.25 Tm 0.25 Y 0.25 )SiO4 phase composition is LiTmSiO4 phase and Y2SiO5 phase. Figure 4 It can be seen from the microwave dielectric properties of the sample at 1060℃, τ f =+31.6ppm / ℃, Q×f=4800GHz, ε r =8.8. The oxygen octahedron is distorted to 7.1×10 -4 τ of LiInSiO4 f The value is -50ppm / ℃; according to the multiphase composite material τ f The calculation formula of the value, τ f [Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 )SiO4]=

[0051] 0.8τ f [Li(Yb 0.25 Ho0.25 Tm 0.25 Y 0.25 )SiO4]+0.2τ f [LiInSiO4] = 0.8 × 31.6 + 0.2 × (-50) = 15.28 ppm / °C, which is much larger than the τ of the above embodiment 1 at 1060°C. f This comparative example also proves that the addition of In element makes the material τ f Closer to zero.

[0052] It should be noted that the present invention is not limited to the above embodiments, and many changes in details are possible. 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 high entropy silicate microwave dielectric material that achieves temperature stability based on regulation of oxygen octahedron distortion, characterized in that: The chemical composition of the material is: Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 )SiO4, the sintering temperature during preparation is 1060~1140℃.

2. The high entropy silicate microwave dielectric material for achieving temperature stability based on regulation of oxygen octahedron distortion according to claim 1, characterized in that: The sintering temperature during preparation is 1060-1100°C.

3. The method for preparing a high entropy silicate microwave dielectric material with temperature stability achieved by regulating oxygen octahedron distortion according to claim 1 or 2, characterized in that: The steps include: (1) Yb2O3, Ho2O3, Tm2O3, In2O3, Y2O3 and Li2CO3 are used as raw materials. 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 ) SiO4 stoichiometric ratio is weighed, and then the weighed raw materials are mixed and ball milled once, and the materials are dried to obtain a dried material; (2) The dried material obtained in step (1) was placed in an alumina crucible and compacted, and the temperature was raised to 1000°C at a heating rate of 3-6°C / min, and then kept at this temperature for 2-6 hours, and then cooled to room temperature with the furnace to obtain Li(Yb 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 )SiO4 calcined material; (3) Li(Yb) obtained in step (2) 0.2 Ho 0.2 Tm 0.2 In 0.2 Y 0.2 ) The SiO4 pre-calcined material is placed in a ball mill and subjected to secondary ball milling to obtain a slurry; (4) drying the slurry obtained in step (3) to constant weight, granulating the slurry, and pressing the slurry into samples; (5) placing the sample obtained in step (4) in a high-temperature sintering furnace, heating the temperature to 400-600°C at a heating rate of 3-6°C / min and keeping the temperature for 2-6 hours, and finally cooling the sample to room temperature to obtain a green sample after debinding; (6) The green sample obtained in step (5) is placed in a high-temperature sintering furnace, heated to 1060-1140°C at a heating rate of 3-6°C / min, and kept warm for 2-6 hours. Finally, the green sample is cooled to room temperature in the furnace to obtain a high entropy silicate microwave dielectric material with a resonant frequency temperature coefficient of near zero.

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

6. The method according to claim 3, characterized in that In step (4), the pressing pressure is 20 MPa, and the size of the cylindrical sample pressed is: diameter 12 mm×thickness 4-6 mm.

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