A low-temperature sintered modified molybdenum-based microwave dielectric ceramic and its preparation method

Abstract

The present invention discloses a low-temperature sintered modified molybdenum-based microwave dielectric ceramic and a preparation method thereof, belonging to the production technology field of microwave dielectric ceramics. The raw materials of the modified molybdenum-based microwave dielectric ceramic are Al2O3, MoO3, MnCO3 and TiO2, and its chemical formula is Al2Mo 3‑x (MnTi) x O 12 , wherein x = 0.01 to 0.02; a method for preparing a modified molybdenum-based microwave dielectric ceramic, comprising the following steps: batching; ball milling, drying, screening, pre-sintering; re-ball milling, drying, granulation; pressing, debinding, and heat preservation to obtain a low-temperature sintered modified molybdenum-based microwave dielectric ceramic, the chemical formula of which is Al2Mo 3‑x (MnTi) x O 12 , wherein x = 0.01 to 0.02. The present invention utilizes (MnTi) 6+ The composite ions partially replace the lattice position of Mo, and with the help of the low melting point of MnCO3, the Al2Mo3O 12 The crystal structure was improved and its optimal sintering temperature was lowered. Finally, the system achieved excellent microwave dielectric properties at a lower sintering temperature (725℃).

Description

Technical Field

[0001] The present invention belongs to the technical field of production of microwave dielectric ceramics, and specifically relates to a molybdenum-based microwave dielectric ceramic and a preparation method thereof, and in particular to a low-temperature sintered modified molybdenum-based microwave dielectric ceramic and a preparation method thereof. Background Art

[0002] Fifth-generation mobile communications technology places higher demands on the high-frequency performance of electronic components, such as excellent frequency selectivity, low insertion loss, and low signal transmission delay. Microwave dielectric ceramics, materials that exhibit specific functionality in the 300MHz to 300GHz range, are used to manufacture key electronic components such as dielectric waveguides, dielectric filters, substrates, and dielectric antennas. Their importance has garnered widespread attention as the demand for technologies such as 5G mobile communications and the Internet of Things (IoT) grows.

[0003] The performance indicators of microwave dielectric ceramics include relative dielectric constant εr, quality factor Q (Q×f reflects the quality factor at a certain resonant frequency), and resonant frequency temperature coefficient τf. Compared with 4G communication systems, 5G networks are densely distributed base station networks. Base station antennas and portable terminals will need to adopt large-scale millimeter-wave (30GHz to 300GHz) phased array antenna technology (Massive MIMO), and their number will show explosive growth. This has greatly stimulated the development of filters towards miniaturization, lightweight, high integration, high frequency, ultra-low insertion loss, and high stability. This requires ceramics to have a high Q value and inexpensive raw materials. At the same time, considering the transmission delay and transmission loss of the signal, the ceramic εr value should also be low (εr ≤ 10). Low-Temperature Cofired Ceramic (LTCC), a novel three-dimensional integrated packaging and interconnect technology, boasts small size, light weight, high reliability, excellent temperature stability, and high-density packaging. It is widely used in wireless communication electronic components, microwave and millimeter-wave substrates, microwave and millimeter-wave functional modules, and high-power devices. Therefore, developing low-temperature sintered microwave dielectric ceramics suitable for LTCC technology presents a technical challenge.

[0004] Because the internal electrodes in LTCC technology are typically silver or copper, ceramics must exhibit excellent high-frequency microwave dielectric properties under low-temperature conditions (for example, the optimal temperature for co-firing with silver should be below 900°C). However, the firing temperature of ceramic materials is generally high (greater than 1100°C), so the majority of low-temperature sintered ceramics for LTCC applications are glass-ceramics. Glass-ceramics refer to materials that incorporate a certain proportion of glass material into a ceramic matrix. Leveraging the glass's low melting point, a liquid phase is formed. This liquid-phase sintering mechanism not only allows for low-temperature sintering, but also achieves excellent microwave dielectric properties through the matching design between the glass additive and the ceramic matrix. However, glass materials generally have high dielectric loss, which significantly degrades the microwave dielectric performance of the ceramic. Furthermore, because different ceramic matrices exhibit significant selectivity for glass additives, the matching design between the two is not universally applicable.

[0005] Molybdenum-based microwave dielectric ceramics are a new type of glass-free low dielectric constant material system. The standard product chemical formula is Al2Mo3O 12 Its sintering temperature is lower than the melting point of silver electrodes (961°C). Unlike glass-ceramics, this type of material does not require the addition of glass additives and typically has a single-phase structure, offering advantages such as structural stability, reliability, and good repeatability. Its low-temperature synthesis characteristics allow for direct densification during low-temperature sintering. Therefore, this type of ceramic has broad potential applications and is a candidate for LTCC dielectrics.

[0006] However, Al2Mo3O 12 The microwave dielectric properties of the system sintered at 800°C are: εr of 6.76, Q×f of 27330 GHz, and τf of -59.5 ppm / °C. While this system exhibits excellent microwave dielectric properties, the higher sintering temperature increases energy consumption and the risk of silver diffusion when co-firing with silver electrodes. Therefore, further reducing the sintering temperature while maintaining excellent performance remains a challenge.

[0007] Generally speaking, microwave dielectric properties can be regulated by single ion or composite ion doping under the premise of forming a solid solution. However, the traditional preparation method of Al2Mo3O12 system does not involve composite ion substitution. Summary of the Invention

[0008] The purpose of the present invention is to provide a low-temperature sintered modified molybdenum-based microwave dielectric ceramic and a preparation method thereof in order to solve the above problems.

[0009] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0010] A low-temperature sintered modified molybdenum-based microwave dielectric ceramic, wherein the raw materials of the low-temperature sintered modified molybdenum-based microwave dielectric ceramic are Al2O3, MoO3, MnCO3 and TiO2, and the chemical formula thereof is Al2Mo 3-x (MnTi) x O 12 , wherein x = 0.01 to 0.02. Among the above raw materials, Al2O3 is aluminum oxide, MoO3 is molybdenum trioxide, MnCO3 is manganese carbonate, and TiO2 is titanium dioxide.

[0011] A method for preparing a low-temperature sintered modified molybdenum-based microwave dielectric ceramic comprises the following steps:

[0012] Step 1: Prepare the raw materials Al2O3, MoO3, MnCO3 and TiO2 according to the chemical formula Al2Mo 3-x (MnTi) x O 12 The ingredients are batched, wherein x=0.01-0.02;

[0013] Step 2: The raw material powder prepared in step 1 is placed in a ball mill, and zirconium balls and anhydrous ethanol are selected as grinding media for ball milling. After the ball milling is completed, the mixed slurry is placed in an oven for drying, and then sieved with a 60-100 mesh screen. The sieved powder is pre-calcined in an atmosphere of 675°C to 700°C for 2-4 hours;

[0014] Step 3: The pre-calcined powder from step 2 is re-loaded into a ball mill, and zirconium balls and anhydrous ethanol are used as grinding media for ball milling. After the ball milling is completed, the mixed slurry is placed in an oven for drying, and an acrylic acid solution is added to the dried powder as a binder for granulation to obtain a ceramic raw material.

[0015] Step 4: Press the ceramic raw material obtained in step 3 into a shape, then remove the binder at a temperature of 400°C to 450°C at a heating rate of 2°C / min to 5°C / min for 2 to 4 hours, and then heat it to 725°C to 775°C at the same rate and keep it at that temperature for 4 to 6 hours to obtain a low-temperature sintered modified molybdenum-based microwave dielectric ceramic, the chemical formula of which is Al2Mo 3-x (MnTi) x O 12 , where x = 0.01 ~ 0.02.

[0016] Preferably, in step 2, the mass ratio of the raw material powder, zirconium balls and anhydrous ethanol is 1:5:(2-4), and the ball milling time is 4-6 hours; in step 3, the mass ratio of the pre-calcined powder, zirconium balls and anhydrous ethanol is 1:5:(2-4), and the ball milling time is 4-6 hours.

[0017] Preferably, the ball milling in step 2 and step 3 is performed by planetary ball milling.

[0018] The beneficial effects of the present invention are:

[0019] The present invention adds MnCO3 and TiO2 to the raw materials to obtain (MnTi) 6+ Composite ions, using (MnTi) 6+ Composite ions partially replace traditional Al2Mo3O 12 The lattice position of Mo in the structure, but (MnTi) 6+ The trace doping of composite ions will not cause Al2Mo3O 12 The crystal structure of Al2Mo3O 12 The crystal structure was improved and the optimal sintering temperature was lowered. Finally, the system achieved excellent microwave dielectric properties at a lower sintering temperature (725 ° C): εr was 6.87 and tanδ was as low as 5.85×10 -4 , Q×f value is as high as 24408GHz (f=14.0GHz); On the one hand, the present invention fills the gap of composite ion doping on Al2Mo3O 12 It fills the research gap in the crystal structure and phase composition of the system, and at the same time further improves the low-temperature sintering characteristics of the system, expands its application potential in the field of LTCC technology, and will promote energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is Al2Mo in the embodiment of the present invention. 2.98 (MnTi) 0.02 O 12 XRD patterns of ceramics;

[0021] Figure 2 It is Al2Mo in the embodiment of the present invention. 2.98 (MnTi) 0.02 O 12 SEM images of ceramics. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the embodiments and drawings:

[0023] The raw materials of the low temperature sintered modified molybdenum-based microwave dielectric ceramic of the present invention are Al2O3, MoO3, MnCO3 and TiO2, and its chemical formula is Al2Mo 3-x (MnTi) x O 12 , where x = 0.01~0.02.

[0024] The method for preparing the low-temperature sintered modified molybdenum-based microwave dielectric ceramic of the present invention comprises the following steps:

[0025] Step 1: Prepare the raw materials Al2O3, MoO3, MnCO3 and TiO2 according to the chemical formula Al2Mo 3-x (MnTi) x O 12 The ingredients are batched, wherein x=0.01-0.02;

[0026] Step 2: The raw material powder prepared in step 1 is loaded into a ball mill, and zirconium balls and anhydrous ethanol are selected as grinding media for planetary ball milling. The mass ratio of raw material powder, zirconium balls, and anhydrous ethanol is 1:5:(2-4), and the ball milling time is 4-6 hours. After the ball milling is completed, the mixed slurry is placed in an oven for drying, and then sieved with a 60-100 mesh sieve. The sieved powder is pre-calcined in an atmosphere of 675°C to 700°C for 2-4 hours;

[0027] Step 3: The pre-calcined powder of step 2 is loaded into a ball mill again, and zirconium balls and anhydrous ethanol are selected as grinding media for planetary ball milling. The mass ratio of the pre-calcined powder, zirconium balls, and anhydrous ethanol is 1:5:(2-4), and the ball milling time is 4-6 hours. After the ball milling is completed, the mixed slurry is placed in an oven for drying, and then an acrylic acid solution is added to the dried powder as a binder for granulation to obtain a ceramic raw material;

[0028] Step 4: Press the ceramic raw material obtained in step 3 into a shape, then remove the binder at a temperature of 400°C to 450°C at a heating rate of 2°C / min to 5°C / min for 2 to 4 hours, and then heat it to 725°C to 775°C at the same rate and keep it at that temperature for 4 to 6 hours to obtain a low-temperature sintered modified molybdenum-based microwave dielectric ceramic, the chemical formula of which is Al2Mo 3-x (MnTi) x O 12 , where x = 0.01 ~ 0.02.

[0029] The present invention is described in detail below with reference to a preferred embodiment:

[0030] Example:

[0031] The modified molybdenum-based microwave dielectric ceramics sintered at low temperature were prepared as follows:

[0032] Step 1: Prepare the raw materials Al2O3, MoO3, MnCO3 and TiO2 according to the chemical formula Al2Mo 2.98 (MnTi) 0.02 O 12 Make the ingredients;

[0033] Step 2: The raw material powder prepared in step 1 is loaded into a ball mill, and zirconium balls and anhydrous ethanol are selected as grinding media for planetary ball milling. The mass ratio of raw material powder, zirconium balls, and anhydrous ethanol is 1:5:3, and the ball milling time is 6 hours. After the ball milling is completed, the mixed slurry is placed in an oven for drying, and then sieved with a 60-mesh sieve. The sieved powder is pre-calcined in an atmosphere of 700°C for 4 hours;

[0034] Step 3: The pre-calcined powder of step 2 is loaded into a ball mill again, and zirconium balls and anhydrous ethanol are selected as grinding media for planetary ball milling. The mass ratio of the pre-calcined powder, zirconium balls, and anhydrous ethanol is 1:5:2, and the ball milling time is 4 hours. After the ball milling is completed, the mixed slurry is placed in an oven for drying, and then an acrylic acid solution is added to the dried powder as a binder for granulation to obtain a ceramic raw material;

[0035] Step 4: The ceramic raw material obtained in step 3 is pressed into shape, and then the binder is removed at 450°C at a heating rate of 2°C / min for 2 hours, and then the temperature is raised to 725°C at the same rate and kept at this temperature for 6 hours to obtain a low-temperature sintered modified molybdenum-based microwave dielectric ceramic, the chemical formula of which is Al2Mo 2.98 (MnTi) 0.02 O 12 .

[0036] The modified molybdenum-based microwave dielectric ceramic Al2Mo prepared in this embodiment is sintered at low temperature. 2.98 (MnTi) 0.02 O 12 X-ray diffraction test (ie XRD test) and scanning electron microscope observation (ie SEM observation) were performed respectively, and the following results were obtained:

[0037] Figure 1 Al2Mo 2.98 (MnTi) 0.02 O 12 The XRD spectrum of the ceramic shows that the peak positions of all diffraction peaks match those of the standard diffraction card JCPDS No.89-8579. In addition, no extra diffraction peaks appear, indicating that the Al2Mo 2.98 (MnTi) 0.02 O 12 The phase structure of the ceramics has not changed, which also shows that (MnTi) 6+ The trace doping of composite ions will not cause Al2Mo3O 12 The crystal structure changes.

[0038] Figure 2 Al2Mo 2.98 (MnTi) 0.02 O 12The SEM image of the ceramic shows that Al2Mo 2.98 (MnTi) 0.02 O 12 The grain growth of the ceramic is sufficient, the grain size is about 3μm, and the microstructure is dense and the porosity is low, indicating that the Al2Mo 2.98 (MnTi) 0.02 O 12 Ceramics have good sintering characteristics.

[0039] Al2Mo was prepared by mixing different raw materials and sintering temperatures. 3-x (MnTi) x O 12 , and conduct tests to obtain the performance parameter results shown in the following table:

[0040]

[0041]

[0042] From the above table data, it can be seen that when the sintering temperature is 725℃, Al2Mo 2.98 (MnTi) 0.02 O 12 The dielectric constant of the ceramic is 5.93, corresponding to the lowest dielectric loss of 5.85×10-4. At this time, the Q×f value also reaches the optimal value of 24408GHz. When the sintering temperature continues to rise, the dielectric constant increases more slowly, while the Q×f value deteriorates to a certain extent. The change in the Q×f value may be attributed to the excessively high sintering temperature causing the grains to grow again, destroying the uniformity of grain growth. 6+ The doping of composite ions, under the premise of ensuring that the ceramic phase structure does not change, makes Al2Mo 2.98 (MnTi) 0.02 O 12 The ceramics have achieved the effect of lower temperature sintering and also achieved better Q×f value, which improved the Al2Mo 2.98 (MnTi) 0.02 O 12 The low-temperature sintering characteristics of ceramics enhance their application potential in the field of LTCC technology.

[0043] The above embodiments are only preferred embodiments of the present invention and are not limitations on the technical solutions of the present invention. Any technical solution that can be implemented on the basis of the above embodiments without creative work should be deemed to fall within the scope of protection of the patent of the present invention.

Claims

1. A low-temperature sintered modified molybdenum-based microwave dielectric ceramic, characterized by: The raw materials of the low temperature sintered modified molybdenum-based microwave dielectric ceramic are Al2O3, MoO3, MnCO3 and TiO2, and its chemical formula is Al2Mo 3-x (MnTi) x O 12 , where x = 0.01 ~ 0.

02.

2. A method for preparing the low-temperature sintered modified molybdenum-based microwave dielectric ceramic according to claim 1, characterized in that: The following steps are involved: Step 1: Prepare the raw materials Al2O3, MoO3, MnCO3 and TiO2 according to the chemical formula Al2Mo 3-x (MnTi) x O 12 The ingredients are batched, wherein x=0.01-0.02; Step 2: The raw material powder prepared in step 1 is placed in a ball mill, and zirconium balls and anhydrous ethanol are selected as grinding media for ball milling. After the ball milling is completed, the mixed slurry is placed in an oven for drying, and then sieved with a 60-100 mesh screen. The sieved powder is pre-calcined in an atmosphere of 675°C to 700°C for 2-4 hours; Step 3: The pre-calcined powder from step 2 is re-loaded into a ball mill, and zirconium balls and anhydrous ethanol are used as grinding media for ball milling. After the ball milling is completed, the mixed slurry is placed in an oven for drying, and an acrylic acid solution is added to the dried powder as a binder for granulation to obtain a ceramic raw material. Step 4: Press the ceramic raw material obtained in step 3 into a shape, then remove the binder at a temperature of 400°C to 450°C at a heating rate of 2°C / min to 5°C / min for 2 to 4 hours, and then heat it to 725°C to 775°C at the same rate and keep it at that temperature for 4 to 6 hours to obtain a low-temperature sintered modified molybdenum-based microwave dielectric ceramic, the chemical formula of which is Al2Mo 3-x (MnTi) x O 12 , where x = 0.01 ~ 0.

02.

3. The method for preparing the low-temperature sintered modified molybdenum-based microwave dielectric ceramic according to claim 2, characterized in that: In the step 2, the mass ratio of the raw material powder, zirconium balls, and anhydrous ethanol is 1:5:(2-4), and the ball milling time is 4-6 hours; in the step 3, the mass ratio of the pre-calcined powder, zirconium balls, and anhydrous ethanol is 1:5:(2-4), and the ball milling time is 4-6 hours.

4. The method for preparing the low-temperature sintered modified molybdenum-based microwave dielectric ceramic according to claim 2 or 3, characterized in that: The ball milling in step 2 and step 3 both adopts planetary ball milling.

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