Li3Mg2SbO6-based ceramic sintering characteristic and quality factor collaborative optimization method

Abstract

The invention discloses a Li3Mg2SbO6-based ceramic sintering characteristic and quality factor collaborative optimization method, which adopts a traditional solid phase process, introduces LiF into a Li3Mg2SbO6 structure, not only can improve the sintering characteristic (inhibits Li3Mg2SbO6 ceramic cracking and reduces the sintering temperature), but also can improve the quality factor (Q * f is increased by nearly one time at most), the dielectric constant is 10.7-11.4, the quality factor Q * f is 87500-95300 GHz, and the Li3Mg2SbO6-based ceramic has a good sintering property. And the temperature coefficient of resonance frequency is-16.0 to-10.5 ppm / DEG C. The method is rich in raw material source, low in cost, simple in preparation process and beneficial to industrial production, and the obtained ceramic material can be widely applied to manufacturing of microwave dielectric substrates, filters, antennas and other microwave devices.

Description

Technical Field

[0001] This invention belongs to the field of electronic ceramics and their manufacturing technology, specifically relating to a method for synergistic optimization of sintering characteristics and quality factor of Li3Mg2SbO6-based ceramics. Background Technology

[0002] Microwave dielectric ceramics are the core dielectric materials used in the fabrication of microwave components (such as resonators, filters, and dielectric antennas), and their performance directly determines the efficiency and stability of these devices in high-frequency signal transmission. With the technological evolution of 5.5G / 6G communication towards higher frequencies and greater integration, signal delay has become more prominent, and heat generation due to system losses has increased significantly, leading to a gradual deterioration in device thermal stability. Microwave dielectric ceramics face stringent challenges in multi-dimensional performance optimization: requiring them to possess low ε... r To reduce signal delay, high Q×f to improve frequency selectivity and reduce device losses and heat generation, and near-zero τ f To improve the thermal stability of the device, it is also required to have a lower sintering temperature to reduce energy consumption and production costs.

[0003] Typically, it is difficult for a single-phase material system to simultaneously meet the requirements of the above three performance parameters. Most single-phase materials with high Q×f values ​​have low ε... r Ceramics typically have a large negative τ. f It possesses a low ε value (-20 ~ -80 ppm / ℃) and a high sintering temperature. Rock salt structure Li3Mg2SbO6 is a rare example that simultaneously exhibits low ε values. r , near zero τ f Novel microwave dielectric materials with high ε values ​​and high Q×f values, but this low ε r Microwave dielectric ceramics also have some drawbacks: firstly, poor sintering characteristics (cracking after sintering, high sintering temperature); secondly, the preparation process of single-phase Li3Mg2SbO6 ceramics is relatively complex, making it unable to meet practical application requirements. Existing technologies mainly address the cracking problem of Li3Mg2SbO6-based ceramics after sintering through Sb-site ion substitution / non-stoichiometric substitution and Mg-site ion substitution. CN 110668794A introduces Sb-site lattice defects into the Li3Mg2SbO6 matrix. These Sb-site lattice defects and oxygen vacancies activate its lattice structure, which not only improves its sintering characteristics (suppressing cracking of Li3Mg2SbO6 ceramics and reducing its sintering temperature) but also improves its microwave dielectric properties (Q×f increased by up to approximately 170%). Its dielectric constant is 9.5–11.0, quality factor Q×f is 41700–86300 GHz, and resonant frequency temperature coefficient is -12.7–-7.9 ppm / ℃. However, the sintering temperature of this method is still as high as 1200-1275℃, which increases energy consumption costs and is not conducive to pollution prevention and emission reduction. Summary of the Invention

[0004] The purpose of this invention is to provide a new method to solve the poor sintering characteristics (cracking, high sintering temperature) of Li3Mg2SbO6 ceramics, which further reduces the ceramic sintering temperature while maintaining its excellent microwave dielectric properties.

[0005] To achieve the above objectives, this invention provides a method for synergistic optimization of the sintering characteristics and quality factor of Li3Mg2SbO6-based ceramics, which comprises the following steps:

[0006] Step 1: According to Li 3.3 Mg2SbO6F 0.3 According to the stoichiometric ratio, the raw materials Li2CO3, MgO, Sb2O3 and LiF are added to a ball mill jar, zirconium balls are used as grinding balls and anhydrous ethanol is used as the grinding medium, and the mixture is thoroughly mixed and milled for 6 to 10 hours, and then dried at 80 to 100°C.

[0007] Step 2: Pre-calcine the dried mixture from Step 1 at 580–620°C for 2–6 hours to obtain pre-calcined powder.

[0008] Step 3: Add the pre-calcined powder obtained in Step 2 into a ball mill jar, use zirconium balls as grinding balls and anhydrous ethanol as the ball milling medium, mix thoroughly and ball mill for 6 to 10 hours, and dry at 80 to 100°C.

[0009] Step 4: Add a 5% (w / w) polyvinyl alcohol aqueous solution to the pre-calcined powder dried in Step 3 for granulation, pass through an 80-120 mesh sieve, and press into cylindrical green bodies using a powder tablet press.

[0010] Step 5: Sinter the cylindrical green body at 1075-1125℃ for 2-10 hours.

[0011] In step 2 above, it is preferable to pre-calcine the dried mixture from step 1 at 600°C for 4 hours.

[0012] In step 5 above, it is preferable to sinter the cylindrical green blank at 1100°C for 5 hours.

[0013] The beneficial effects of this invention are as follows:

[0014] This invention optimizes the sintering characteristics and quality factor of Li3Mg2SbO6 by introducing LiF into the structure, based on multiple mechanisms. LiF forms a liquid phase at low temperatures, promoting particle rearrangement; F enters the oxygen lattice, lowering the lattice activation energy and effectively regulating the local structure and chemical bonding characteristics of Li3Mg2SbO6-based ceramics. This synergistic effect not only improves its sintering characteristics (inhibiting cracking in Li3Mg2SbO6 ceramics and lowering its sintering temperature) but also improves its microwave dielectric properties (Q×f is increased by nearly 100%). The raw materials used in this invention are abundant and inexpensive, the preparation process is simple, and the resulting ceramic material has lower pre-sintering / sintering temperatures and dielectric losses, making it widely applicable in the manufacture of microwave dielectric substrates, filters, antennas, and other microwave devices. Attached Figure Description

[0015] Figure 1 This is an X-ray powder diffraction pattern of the microwave dielectric ceramic prepared in Example 1.

[0016] Figure 2 This is an optical photograph of the cylindrical microwave dielectric ceramic prepared in Example 1.

[0017] Figure 3 This is a scanning electron microscope image of the cross-sectional thermal corrosion of the microwave dielectric ceramic prepared in Example 1. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0019] Example 1

[0020] Step 1: According to Li 3.3 Mg2SbO6F 0.3 Weigh out the raw materials Li2CO3 3.241g, MgO 2.132g, Sb2O3 4.220g and LiF 0.227g according to the stoichiometric ratio. Put the raw material mixture with zirconium balls and anhydrous ethanol into a nylon ball mill jar at a mass ratio of 1:2:2, mix thoroughly and ball mill for 8 hours, and dry at 85℃ for 5 hours.

[0021] Step 2: Place the dried mixture from Step 1 into an alumina crucible and pre-calcine it at 600°C for 4 hours to obtain pre-calcined powder.

[0022] Step 3: Load the pre-calcined powder into a nylon ball mill jar, add zirconium balls and anhydrous ethanol. The mass ratio of pre-calcined powder to zirconium balls and anhydrous ethanol is 1:2:2. Mix thoroughly and ball mill for 8 hours, then dry at 85°C for 5 hours.

[0023] Step 4: Add 5% (by weight) of a 5% (by mass) polyvinyl alcohol aqueous solution to the pre-calcined powder dried in Step 3 for granulation. Pass the granules through a 120-mesh sieve and press them into cylindrical green bodies with a diameter of 10 mm and a thickness of 5 mm using a powder press at a pressure of 4 MPa.

[0024] Step 5: Sinter the cylindrical green body from Step 4 at 1100℃ for 5 hours to prepare microwave dielectric ceramic.

[0025] Example 2

[0026] In step 5 of this embodiment, the cylindrical green body is sintered at 1075°C for 5 hours. The other steps are the same as in embodiment 1 to obtain microwave dielectric ceramic.

[0027] Example 3

[0028] In step 5 of this embodiment, the cylindrical green body is sintered at 1125°C for 5 hours. The other steps are the same as in embodiment 1 to obtain microwave dielectric ceramic.

[0029] The inventors characterized the microwave dielectric ceramic prepared in Example 1 using a Raguku D / Max 2550 (Japan) X-ray diffractometer. The results are shown in [Figure 1]. Figure 1 .Depend on Figure 1 It is evident that the prepared microwave dielectric ceramic is composed of a pure phase of rock salt structure, Li3Mg2SbO6, and no other obvious phases were detected.

[0030] The inventors used the closed-cavity resonance method and a ZVB20 vector network analyzer (manufactured by Rohde & Schwarz, Germany) to test the microwave dielectric properties of the microwave dielectric ceramics prepared in Examples 1-3. The temperature coefficient of the resonant frequency of the samples was tested within the temperature range of 20-80℃. 01δ The resonant mode frequency is in the range of 10.0–12.0 GHz, and the test results are consistent with those of Li3Mg2Sb prepared in Example 1 of CN110668794A. 0.9 O 6-δ Ceramics, Li3Mg reported in existing literature 1.94 Zn 0.06 SbO6 ceramic material (Chemical bond characteristics and microwave dielectric properties ofLi3Mg 2-x Zn x SbO6ceramics with near-zero τ f The microwave dielectric properties of the samples were compared (see Table 1).

[0031] Table 1 Comparison of microwave dielectric properties of different ceramic materials

[0032]

[0033] Experimental results show that, by introducing LiF into the Li3Mg2SbO6 structure in Examples 1-3 of this invention, not only can cylindrical Li3Mg2SbO6-based ceramics with intact and undamaged surfaces be obtained (see...) Figure 2 ), lower its densification sintering temperature (see Figure 3 Furthermore, it can improve its microwave dielectric properties (Q×f is increased by up to about 1 time). Simultaneously, it is similar to the literature report of Zn element substitution at the Mg site in Li3Mg. 1.94 Zn 0.06 SbO6 ceramics and the Li3Mg2Sb ceramic disclosed in patent CN 110668794A by introducing Sb site defects. 0.9 O 6-δ Compared to ceramics, Examples 1-3 of this invention, by introducing LiF into the Li3Mg2SbO6 structure, not only solved the cracking problem of Li3Mg2SbO6 ceramics, but also resulted in microwave dielectric ceramics with lower pre-sintering / sintering temperatures and dielectric losses. Therefore, this invention provides another novel approach to solving sintering cracking in Li3Mg2SbO6-based ceramics and improving their microwave dielectric properties.

Claims

1. A method for synergistic optimization of sintering characteristics and quality factor of Li3Mg2SbO6-based ceramics, characterized in that: The method includes the following steps: Step 1: According to Li 3.3 Mg2SbO6F 0.3 According to the stoichiometric ratio, the raw materials Li2CO3, MgO, Sb2O3 and LiF were added into a ball mill jar, zirconium balls were used as grinding balls and anhydrous ethanol was used as the ball milling medium, and the mixture was thoroughly mixed and ball milled for 6 to 10 hours, and then dried at 80 to 100°C. Step 2: Pre-calcine the dried mixture from Step 1 at 580–620°C for 2–6 hours to obtain pre-calcined powder; Step 3: Add the pre-calcined powder obtained in Step 2 into a ball mill jar, use zirconium balls as grinding balls and anhydrous ethanol as the ball milling medium, mix thoroughly and ball mill for 6 to 10 hours, and dry at 80 to 100°C; Step 4: Add a 5% (w / w) polyvinyl alcohol aqueous solution to the pre-calcined powder dried in Step 3 for granulation, pass through an 80-120 mesh sieve, and press into cylindrical green bodies using a powder tablet press. Step 5: Sinter the cylindrical green body at 1075-1125℃ for 2-10 hours.

2. The method for synergistic optimization of sintering characteristics and quality factor of Li3Mg2SbO6-based ceramics according to claim 1, characterized in that: In step 2, the mixture dried in step 1 is pre-fired at 600°C for 4 hours.

3. The method for synergistic optimization of sintering characteristics and quality factor of Li3Mg2SbO6-based ceramics according to claim 1, characterized in that: In step 5, the cylindrical green body is sintered at 1100℃ for 5 hours.

Images