A high-Q resonator based on SrTiO3-LaAlO3-based microwave dielectric ceramic materials and its preparation method

Abstract

The object of the present invention is to provide a preparation process of SrTiO3-LaAlO3-based microwave dielectric ceramics and their resonators, with the chemical formula Sr(y-z)CazTi1-mCemO3-xLa1-nGanAlO3, where 0.7 ≤ x ≤ 1.15, 0.98 ≤ y ≤ 1.01, 0.05 ≤ z ≤ 0.15; 0.001 ≤ m ≤ 0.01; 0.001 ≤ n ≤ 0.015; the sintering conditions of the resonator are: in air, the sintering temperature is 1500 °C to 1600 °C; the resonance frequency is 2.4 to 2.6 GHz, the Q value is 17700 to 19800, and the temperature coefficient of resonance frequency is 0 ± 5 ppm / °C. The sintering conditions of this resonator are relatively simple, the sintering atmosphere is air, the performance has been greatly improved, the performance is stable, and it can meet the application requirements of modern communication technologies, and can be widely used in the preparation of microwave components such as microwave dielectric resonators.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic information functional materials, and relates to a preparation method of microwave dielectric ceramic materials and resonators, and particularly relates to high-quality factor microwave communication components such as dielectric resonators and dielectric filters that can be used in modern communication technologies. Background Art

[0002] The frequencies used in microwave communication technologies are mainly between 300 MHz and 300 GHz, and it has the characteristics of high frequency, wide bandwidth, large information capacity, multi-channel communication, etc. Microwave dielectric resonators play a crucial role in the field of microwave communication due to their small size, light weight, high dielectric constant and Q value, and good temperature stability. A dielectric resonator is a most basic microwave component. Using dielectric resonators, microwave circuits such as filters, oscillators and antennas can be formed, which helps to realize the miniaturization and high frequency of microwave circuits and systems. Its development in circuit applications is related to the urgent requirements of the development of space and military electronic technologies for the miniaturization, integration and high reliability of microwave circuits. With the rapid development of 5G communication technology, the requirements for microwave communication devices have become more stringent, which also means that more excellent underlying materials for microwave communication technologies are needed to prepare resonators with excellent performance. Traditional metal devices cannot meet the performance requirements of the new generation of communication systems due to the limitations of weight and volume. Therefore, microwave dielectric ceramics have attracted much attention as a key material. Microwave dielectric ceramics have excellent properties such as low dielectric loss, high quality factor and stable resonant frequency temperature coefficient, and these properties directly affect the performance of microwave resonators prepared using them.

[0003] (1-x)MTiO3-xLnAlO3 (M = Ba, Sr, Ca; Ln = La, Nd, Sm, etc.) series of microwave dielectric ceramics are a type of composite ceramics with a perovskite solid solution structure, and MTiO3-LnAlO3 has the advantages of low dielectric loss, adjustable dielectric constant and good microwave performance. Its dielectric constant and dielectric loss can both meet the research requirements, and it is widely used in fields such as military radars, mobile communication base stations and Ku-band digital TV receiving systems. SrTiO3-LaAlO3-based ceramics are a type of microwave dielectric ceramics with good prospects and have been widely studied due to their excellent dielectric properties. When the ratio of SrTiO3 to LaAlO3 reaches a certain value, its dielectric constant is ε r = 40, Q×f ≥ 40000 GHz, frequency temperature coefficient τ f= 0 ± 5 ppm / °C. However, for pure SrTiO3-LaAlO3, due to the excessively high sintering temperature (>1650 °C) and the phenomenon of oxygen loss at high temperature during sintering, resulting in a black core, its dielectric properties are severely deteriorated. Therefore, the application value of pure SrTiO3-LaAlO3 ceramics is relatively low. The research on SrTiO3-LaAlO3 microwave dielectric ceramics began in the 1990s. In 1998, Sun PH, Nakamura T et al. reported the properties of SrTiO3-LaAlO3 ceramics in the article "Dielectric behavior of (1-x)SrTiO3-xLaAlO3 solid solution system at microwave frequencies" in the Japanese Journal of Applied Physics. In 1999, Seo-Yong Cho et al. reported the dielectric properties of ceramics sintered by separately synthesizing SrTiO3 and LaAlO3 powders and then mixing them in a certain proportion in the literature "Mixture-like behavior in the microwave dielectric properties of the (1-x)SrTiO3-xLaAlO3 system" in Materials Research Bulletin. In 2001, Huang C L et al. published the research "Improved high Q value of 0.5LaA1O3-0.5SrTiO3 microwave dielectric ceramics at low sintering" in Materials Research Bulletin. When 0.25%-1% wt of B2O3 was doped, the sintering temperature of 0.5LaA1O3-0.5SrTiO3 ceramics was reduced to 1430 °C, but the large addition of the glass phase led to the deterioration of microwave properties. In the following years, a large number of researchers studied SrTiO3-LaAlO3 series ceramics, and their research mainly focused on the phase change mechanism during the composite process of ceramics and doping CuO etc. to reduce the sintering temperature.In 2009, T. Shimada et al. reported in the journal Ferroelectrics, "Effect of Sintering Atmosphere on Dielectric Properties of SrTiO3-LaAlO3 System." Sintering ceramics at different O2 partial pressures, they found that as the proportion of SrTiO3 increased, the dielectric loss of SrTiO3-LaAlO3 ceramics increased; increasing the oxygen content in the sintering atmosphere decreased the dielectric loss. XPS analysis concluded that this was due to the semiconductorization of SrTiO3-LaAlO3 ceramics at high temperatures, with the mechanism being Ti. 4+ →Ti 3+ , which produces oxygen vacancies and causes the performance of microwave dielectric ceramics to deteriorate. Ceramics with high-quality microwave dielectric properties can be obtained by sintering in an O2 atmosphere, but the conditions required increase the requirements for sintering equipment and require higher sintering temperatures, which makes the promotion of practical ceramics very difficult. In 2015, Zhang et al. published an article in Ceramics International titled "(1-x)LaAlO3-xCa 0.2 Sr 0.8 Investigation on microwave dielectric properties and microstructures of (1-x)LaAlO3-xCa 0.2 Sr 0.8 TiO3 ceramics) reported (1-x)LaAlO3-xCa 0.2 Sr 0.8 The structure, microstructure and microwave dielectric properties of TiO3 ceramics confirm the formation of solid solution. Its lattice parameters, average grain size and dielectric constant (ε r )With Ca 0.2 Sr 0.8 The quality factor (Q×f) of TiO3 increases with the increase of TiO3 dosage, while the quality factor (Q×f) decreases. 3+ Effect of GaAs Substitution on Microwave Dielectric Properties of 0.67CaTiO3-0.33LaAlO3 Ceramics 3+substitution on the microwave dielectric properties of 0.67CaTiO3-0.33LaAlO3 ceramics), Dou et al. prepared 0.67CaTiO3-0.33La(Al 1-x Ga x )O3(0<x<0.4)(CTLAG) pure perovskite-structured ceramics and investigated the effect of Ga 3+ substitution for Al 3+ on the microwave dielectric properties of the ceramics. The article found that with the increase of Ga content, the ionic polarization of the ceramics increased, resulting in an increase in the dielectric constant (ε r ). At the same time, with the increase of Ga content, the tolerance factor (t) and the A-site bond valence of CTLAG ceramics were both considered to have an impact on the temperature coefficient of the resonance frequency (τ f ). The results also showed that the quality factor (Q×f) increased with Ga 3+It changes with the increase in content, which is due not only to internal factors but also to external factors such as bimodal grain size distribution, change in relative density, and filler fraction. In 2017, Huang et al. reported in Ceramics International the effects of CaO / SnO2 additives on the sintering performance, phase composition, microstructure, and dielectric properties of 0.6SrTiO3-0.4LaAlO3 (6ST-4LA) microwave dielectric ceramics prepared by the conventional solid-state reaction method. The results showed that CaO / SnO2 as an additive had no obvious effect on the phase composition of 6ST-4LA ceramics, and all samples exhibited a pure ABO3 perovskite structure. Adding an appropriate amount of CaO / SnO2 not only effectively reduced the sintering temperature from 1550 °C to 1400 °C, but also improved the dielectric properties due to the formation of a perovskite solid solution, and reduced microstructure defects and internal losses. In 2022, Huang et al. reported in Journal of Materials Science: Materials in Electronics the article "Effect of Si / Mg mole ratio on the phase transformation, sintering, and dielectric properties of 0.63SrTiO3-0.37LaAlO3 ceramics", in which 0.63SrTiO3-0.37LaAlO3 (63ST-37LA) ceramics were prepared by the solid-phase method, and the effects of the Si / Mg mole ratio on the phase transformation, sintering, and dielectric characteristics of 63ST-37LA ceramics were studied. When the molar ratio R = 0.53 and the MgO addition amount was 2 mol%, at 1350 °C, the dielectric characteristics of 63ST-37LA ceramics were remarkable, with a dielectric constant of 45.97, a Q central point f value of 69928 GHz, and a frequency temperature coefficient of 1.7 ppm / °C.In 2022, Luo et al. reported the article "Effects of Y2O3 doping on the dielectric properties and microstructures of SrTiO3-LaAlO3 microwave dielectric ceramics" in "Ceramics International". The article prepared Y2O3-doped SrTiO3-LaAlO3 (ST-LA) microwave dielectric ceramics by the conventional solid-state reaction method. X-ray energy spectrum analysis showed that Y... 3+ was evenly distributed in the grains. The change in the doping amount of Y2O3 significantly affected the dielectric properties of ST-LA ceramics at microwave frequencies. The 0.55SrTiO3-0.45LaAlO3 ceramic doped with 0.3wt% Y2O3 had excellent microwave dielectric properties, ε r = 44.01, Q×f = 59065 GHz (5.966 GHz), and τ f = 6.09 ppm / °C.

[0004] In summary, based on SrTiO3-LaAlO3-based ceramics, by overcoming the black core formed during sintering, studying microwave dielectric ceramics with high quality factor (high Q×f value), which can be sintered at medium temperature in air (<1600 °C), have low raw material cost and good process repeatability, and using this dielectric ceramic to prepare high-quality factor resonators, has great scientific research value and market prospects, and has the potential to be applied to high-performance resonators. Summary of the Invention

[0005] The object of the present invention is to provide a preparation process for SrTiO3-LaAlO3-based microwave dielectric ceramics and their resonators. The resonator made of this microwave dielectric ceramic has a dielectric constant close to 40, a relatively high Q value, a low frequency temperature coefficient, and a sintering temperature less than 1600 °C, high stability, is easy to industrialize, and can be widely used in the preparation of microwave components such as microwave dielectric resonators.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A SrTiO3-LaAlO3-based microwave dielectric ceramic, whose chemical formula is Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1- n Ga nAlO3, wherein 0.70≤x≤1.15, 0.98≤y≤1.01, 0.05≤z≤0.15; 0.001≤m≤0.01; 0.001≤n≤0.015; in the above-mentioned microwave dielectric ceramic material, the role of Ca replacing Sr is to lower the sintering temperature and adjust the temperature coefficient; the role of Ce replacing Ti is to reduce the reduction of tetravalent titanium in the ceramic and improve the microwave dielectric properties; the role of Ga replacing La is to overcome the defects generated during its high-temperature sintering process, thereby improving the microwave dielectric properties; the addition of the above-mentioned elements to SrTiO3-LaAlO3-based microwave dielectric ceramics enables it to be sintered in air and adjust the microwave dielectric properties.

[0008] The present invention also provides a resonator based on SrTiO3-LaAlO3-based microwave dielectric ceramics, wherein the resonator is a microwave dielectric ceramic having a chemical formula of Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3, wherein 0.70≤x≤1.15, 0.98≤y≤1.01, 0.05≤z≤0.15; 0.001≤m≤0.01; 0.001≤n≤0.015; the sintering conditions of the resonator are: in air, the sintering temperature is 1500℃~1600℃; the resonant frequency is 2.4~2.6GHz, the Q value is 17700~19800, and the resonant frequency temperature coefficient is 0±5ppm / ℃.

[0009] In addition, the present invention also provides a method for preparing a resonator based on SrTiO3-LaAlO3-based microwave dielectric ceramics, comprising the following steps:

[0010] Step 1: Ingredients: CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3 and TiO2 are used as raw materials, according to the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n The raw materials SrCO3, CaCO3, La2O3, Al2O3 and TiO2 except CeO2 and Ga2O3 are mixed in a molar ratio to obtain a mixture, wherein 0.70≤x≤1.15, 0.98≤y≤1.01, 0.05≤z≤0.15; 0.001≤m≤0.01; 0.001≤n≤0.015; and the purity of each raw material is >99.5%.

[0011] Step 2: Primary ball milling: The mixture prepared in Step 1 is subjected to primary ball milling with deionized water and zirconium balls. The mass ratio of the mixture, deionized water, and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, the milled material is dried at 110°C and sieved through a 60-mesh sieve to obtain the primary milled material.

[0012] Step 3: Pre-sintering: The primary milled material obtained in Step 2 is pre-sintered at a temperature of 1300°C - 1500°C for 2 - 5 hours to obtain the pre-sintered powder.

[0013] Step 4: Sieving: The powder obtained in Step 3 is sieved through a 60-mesh sieve to obtain a powder with fine particles.

[0014] Step 5: Secondary ball milling: The powder after sieving in Step 4 is added to the weighed CeO2 and Ga2O3 raw materials in Step 1 and mixed evenly. Then, it is subjected to secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixture, alcohol, and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, the obtained slurry is dried at 80°C to obtain the dried powder after secondary ball milling.

[0015] Step 6: Granulation: Deionized water and a polyvinyl alcohol solution with a concentration of 5% - 7% are added to the dried powder after secondary ball milling obtained in Step 5 and mixed evenly. The mass ratio of the powder, deionized water, and polyvinyl alcohol solution is 1:1 - 2:0.15 - 0.3. After mixing evenly, the obtained mixed slurry is spray granulated using a spray granulation device to obtain the dried powder.

[0016] Step 7: Molding: The dried powder obtained in Step 6 is placed into a mold and dry-pressed into a green body.

[0017] Step 8: Sintering: The green body obtained in Step 7 is sintered at a temperature of 1500°C - 1600°C in an air atmosphere for 4 - 10 hours to obtain the final resonator device.

[0018] Compared with the existing technology, the present invention has the following characteristics:

[0019] 1. The formula of this resonator does not contain volatile or heavy metal elements such as Pb and Cd, and it is an environmentally friendly and pollution-free dielectric resonator.

[0020] 2. The sintering temperature of SrTiO3-LaAlO3 ceramics without adding doping elements is greater than 1650°C, and the Q value of the resonator prepared using it is relatively low. The sintering temperature of this ceramic is between 1500°C and 1600°C. The Q value of the resonator using this dielectric ceramic is higher, and the preparation process has certain energy-saving advantages.

[0021] 3. The sintering conditions of this resonator are relatively simple. The sintering atmosphere is air. There has been a significant improvement in performance, and the performance is stable, which can meet the application requirements of modern communication technologies and has great practical value for popularization. It can be widely used in the preparation of microwave components such as microwave dielectric resonators.

[0022] 4. The raw materials are abundantly supplied in the country and are inexpensive, making them suitable for manufacturing high-performance microwave communication components in modern communication technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the XRD analysis result of the resonator prepared in Example 3 of the present invention.

[0024] Figure 2 It is the SEM image of the resonator prepared in Example 3 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] A SrTiO3-LaAlO3-based microwave dielectric ceramic. Its chemical formula is Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1- n Ga n AlO3, where 0.70 ≤ x ≤ 1.15, 0.98 ≤ y ≤ 1.01, 0.05 ≤ z ≤ 0.15; 0.001 ≤ m ≤ 0.01; 0.001 ≤ n ≤ 0.015; in the above microwave dielectric ceramic material, the role of Ca substituting Sr is to reduce the sintering temperature and adjust the temperature coefficient; the role of Ce substituting Ti is to reduce the reduction of tetravalent titanium in the ceramic and improve the microwave dielectric properties; the role of Ga substituting La is to overcome the defects generated during its high-temperature sintering process, thereby improving the microwave dielectric properties; doping the above elements into the SrTiO3-LaAlO3-based microwave dielectric ceramic enables it to be sintered in air and adjust the microwave dielectric properties.

[0027] The resonator prepared using the above-mentioned microwave dielectric ceramic has a sintering temperature in air of 1500°C to 1600°C, a resonant frequency of 2.4 to 2.6 GHz, a Q value of 17000 to 19800, a resonant frequency temperature coefficient of 0±5ppm / °C, and a dense structure and good mechanical properties. Therefore, it can be used to prepare microwave components such as microwave dielectric resonators.

[0028] Example 1

[0029] Step 1: Ingredients: CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3 and TiO2 are used as raw materials, according to the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n The raw materials SrCO3, CaCO3, La2O3, Al2O3 and TiO2 except CeO2 and Ga2O3 were mixed to obtain a mixed material.

[0030] Step 2: primary ball milling: ball mill the mixture prepared in step 1 with deionized water and zirconium balls. The mass ratio of the mixture, deionized water and zirconium balls is 1:1-2:1.5-2. The ball milling time is 5-10 hours. After ball milling, the ball mill is dried at 110°C and passed through a 60-mesh sieve to obtain a primary ball mill.

[0031] Step 3: Pre-calcination: Pre-calcine the primary ball mill material obtained in step 2 at 1300° C. for 3 hours to obtain pre-calcined powder.

[0032] Step 4: Sieve: Pass the powder obtained in step 3 through a 60-mesh sieve to obtain a powder with fine particles.

[0033] Step 5: Secondary ball milling: Add the powder sieved in step 4 to the weighed CeO2 and Ga2O3 raw materials in step 1 and mix them evenly, then perform secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixture, alcohol and zirconium balls is 1:1~2:1.5~2. The ball milling time is 5~10 hours. After ball milling, the obtained slurry is dried at 80°C to obtain secondary ball milled dried powder.

[0034] Step 6: Granulation: Add deionized water and a polyvinyl alcohol solution with a concentration of 5% to 7% to the secondary ball-milled dried powder obtained in step 5 and mix evenly. The mass ratio of powder, deionized water and polyvinyl alcohol solution is 1:1 to 2:0.15 to 0.3. After mixing evenly, use a spray granulation device to spray granulate the obtained mixed slurry to obtain a dry powder.

[0035] Step 7: Molding: Place the dried powder obtained in Step 6 into a mold and perform dry pressing to form a green body.

[0036] Step 8: Sintering: Sinter the green body obtained in Step 7 at a temperature of 1500 °C and in an air atmosphere for 9 hours to obtain the final resonator device.

[0037] Example 2

[0038] Step 1: Batching: Using CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3, and TiO2 as raw materials, batch according to the molar ratio of the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3 (x = 0.85, y = 0.99, z = 0.15, m = 0.003, n = 0.015). Mix the SrCO3, CaCO3, La2O3, Al2O3, and TiO2 raw materials except for CeO2 and Ga2O3 to obtain a mixed material.

[0039] Step 2: Primary ball milling: Perform primary ball milling on the mixed material prepared in Step 1 with deionized water and zirconium balls. The mass ratio of the mixed material, deionized water, and zirconium balls is 1:1 - 2:1.5 - 2, the ball milling time is 5 - 10 hours. After ball milling, dry the ball milled material at 110 °C and pass through a 60-mesh sieve to obtain the primary ball milled material.

[0040] Step 3: Pre-sintering: Pre-sinter the primary ball milled material obtained in Step 2 at a temperature of 1350 °C for 4 hours to obtain the pre-sintered powder.

[0041] Step 4: Sieving: Pass the powder obtained in Step 3 through a 60-mesh sieve to obtain a powder with fine particles.

[0042] Step 5: Secondary ball milling: Add the sieved powder obtained in Step 4 to the CeO2 and Ga2O3 raw materials weighed in Step 1, mix evenly, and then perform secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixed material, alcohol, and zirconium balls is 1:1 - 2:1.5 - 2, the ball milling time is 5 - 10 hours. After ball milling, dry the obtained slurry at 80 °C to obtain the dried powder of secondary ball milling.

[0043] Step 6: Granulation: Deionized water and a polyvinyl alcohol solution with a concentration of 5% - 7% are added to the secondary ball-milled and dried powder obtained in Step 5 and mixed evenly. The mass ratio of the powder, deionized water, and polyvinyl alcohol solution is 1:1 - 2:0.15 - 0.3. After mixing evenly, a spray granulation device is used to perform spray granulation on the obtained mixed slurry to obtain a dry powder.

[0044] Step 7: Molding: The dry powder obtained in Step 6 is placed into a mold and dry-pressed to form a green body.

[0045] Step 8: Sintering: The green body obtained in Step 7 is sintered at a temperature of 1550 °C and in an air atmosphere for 6 hours to obtain the final resonator device.

[0046] Example 3

[0047] Step 1: Batching: Using CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3, and TiO2 as raw materials, batching is carried out according to the molar ratio of the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3 (x = 0.75, y = 1, z = 0.15, m = 0.005, n = 0.005). The raw materials of SrCO3, CaCO3, La2O3, Al2O3, and TiO2 except CeO2 and Ga2O3 are mixed to obtain a mixed material.

[0048] Step 2: Primary ball milling: The mixed material prepared in Step 1 is subjected to primary ball milling with deionized water and zirconium balls. The mass ratio of the mixed material, deionized water, and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, the ball-milled material is dried at 110 °C and passed through a 60-mesh sieve to obtain a primary ball-milled material.

[0049] Step 3: Pre-sintering: The primary ball-milled material obtained in Step 2 is pre-sintered at a temperature of 1400 °C for 4 hours to obtain a pre-sintered powder.

[0050] Step 4: Sieving: The powder obtained in Step 3 is passed through a 60-mesh sieve to obtain a powder with fine particles.

[0051] Step 5: Secondary ball milling: The powder after sieving in Step 4 is added with the CeO2 and Ga2O3 raw materials weighed in Step 1 and mixed evenly, and then subjected to secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixed material, alcohol, and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, the obtained slurry is dried at 80 °C to obtain a secondary ball-milled and dried powder.

[0052] Step 6: Granulation: Add deionized water equivalent to 1 to 2 times the mass of the secondary ball-milled and dried powder obtained in Step 5, and a polyvinyl alcohol solution with a concentration of 5% to 7% and a mass of 15% to 30% of the secondary ball-milled and dried powder. After mixing evenly, use a spray granulation device to spray granulate the obtained mixed slurry to obtain a dry powder.

[0053] Step 7: Molding: Place the dry powder obtained in Step 6 into a mold and dry-press it to form a green body.

[0054] Step 8: Sintering: Sinter the green body obtained in Step 7 at a temperature of 1570 °C and an atmosphere of air for 7 hours to obtain the final resonator device.

[0055] Example 4

[0056] Step 1: Batching: Using CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3, and TiO2 as raw materials, batch according to the molar ratio of the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3 (x = 1.05, y = 1, z = 0.1, m = 0.01, n = 0.005). Mix the raw materials of SrCO3, CaCO3, La2O3, Al2O3, and TiO2 except CeO2 and Ga2O3 to obtain a mixed material.

[0057] Step 2: Primary ball milling: Perform primary ball milling on the mixed material prepared in Step 1 with deionized water and zirconium balls. The mass ratio of the mixed material, deionized water, and zirconium balls is 1:1 to 2:1.5 to 2, and the ball milling time is 5 to 10 hours. After ball milling, dry the ball-milled material at 110 °C and pass it through a 60-mesh sieve to obtain the primary ball-milled material.

[0058] Step 3: Pre-sintering: Pre-sinter the primary ball-milled material obtained in Step 2 at a temperature of 1370 °C for 4.5 hours to obtain a pre-sintered powder.

[0059] Step 4: Sieving: Pass the powder obtained in Step 3 through a 60-mesh sieve to obtain a powder with fine particles.

[0060] Step 5: Secondary ball milling: Add the powder sieved in Step 4 to the CeO2 and Ga2O3 raw materials weighed in Step 1, mix evenly, and then perform secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixed material, alcohol, and zirconium balls is 1:1 to 2:1.5 to 2, and the ball milling time is 5 to 10 hours. After ball milling, dry the obtained slurry at 80 °C to obtain the secondary ball-milled and dried powder.

[0061] Step 6: Granulation: Deionized water and a polyvinyl alcohol solution with a concentration of 5% - 7% are added to the secondary ball-milled and dried powder obtained in Step 5 and mixed evenly. The mass ratio of the powder, deionized water, and polyvinyl alcohol solution is 1:1 - 2:0.15 - 0.3. After mixing evenly, the obtained mixed slurry is spray granulated using a spray granulation device to obtain a dry powder.

[0062] Step 7: Molding: The dry powder obtained in Step 6 is placed into a mold and dry-pressed to form a green body.

[0063] Step 8: Sintering: The green body obtained in Step 7 is sintered at a temperature of 1530 °C in an air atmosphere for 6 hours to obtain the final resonator device.

[0064] Example 5

[0065] Step 1: Batching: Using CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3, and TiO2 as raw materials, batching is carried out according to the molar ratio of the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3 (x = 1.1, y = 1.01, z = 0.2, m = 0.007, n = 0.003). The raw materials of SrCO3, CaCO3, La2O3, Al2O3, and TiO2 except CeO2 and Ga2O3 are mixed to obtain a mixed material.

[0066] Step 2: Primary ball milling: The mixed material prepared in Step 1 is subjected to primary ball milling with deionized water and zirconium balls. The mass ratio of the mixed material, deionized water, and zirconium balls is 1:1 - 2:1.5 - 2, the ball milling time is 5 - 10 hours. After ball milling, the ball-milled material is dried at 110 °C and sieved through a 60-mesh sieve to obtain a primary ball-milled material.

[0067] Step 3: Pre-sintering: The primary ball-milled material obtained in Step 2 is pre-sintered at a temperature of 1420 °C for 4.5 hours to obtain a pre-sintered powder.

[0068] Step 4: Sieving: The powder obtained in Step 3 is sieved through a 60-mesh sieve to obtain a powder with fine particles.

[0069] Step 5: Secondary ball milling: The powder after sieving in Step 4 is added with the CeO2 and Ga2O3 raw materials weighed in Step 1 and mixed evenly, and then subjected to secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixed material, alcohol, and zirconium balls is 1:1 - 2:1.5 - 2, the ball milling time is 5 - 10 hours. After ball milling, the obtained slurry is dried at 80 °C to obtain a secondary ball-milled and dried powder.

[0070] Step 6: Granulation: Deionized water and a polyvinyl alcohol solution with a concentration of 5% - 7% are added to the secondary ball-milled and dried powder obtained in Step 5 and mixed evenly. The mass ratio of the powder, deionized water, and polyvinyl alcohol solution is 1:1 - 2:0.15 - 0.3. After mixing evenly, a spray granulation device is used to perform spray granulation on the obtained mixed slurry to obtain a dry powder.

[0071] Step 7: Molding: The dry powder obtained in Step 6 is placed into a mold and dry-pressed into a green body.

[0072] Step 8: Sintering: The green body obtained in Step 7 is sintered at a temperature of 1600°C and in an air atmosphere for 5 hours to obtain the final resonator device.

[0073] Example 6

[0074] Step 1: Batching: Using CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3, and TiO2 as raw materials, batching is carried out according to the molar ratio of the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3 (x = 0.78, y = 1.01, z = 0.1, m = 0.005, n = 0.01). The raw materials of SrCO3, CaCO3, La2O3, Al2O3, and TiO2 except CeO2 and Ga2O3 are mixed to obtain a mixed material.

[0075] Step 2: Primary ball milling: The mixed material prepared in Step 1 is subjected to primary ball milling with deionized water and zirconium balls. The mass ratio of the mixed material, deionized water, and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, the ball-milled material is dried at 110°C and sieved through a 60-mesh sieve to obtain a primary ball-milled material.

[0076] Step 3: Pre-sintering: The primary ball-milled material obtained in Step 2 is pre-sintered at a temperature of 1450°C for 4 hours to obtain a pre-sintered powder.

[0077] Step 4: Sieving: The powder obtained in Step 3 is sieved through a 60-mesh sieve to obtain a powder with fine particles.

[0078] Step 5: Secondary ball milling: Add the powder sieved in step 4 to the weighed CeO2 and Ga2O3 raw materials in step 1 and mix them evenly, then perform secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixture, alcohol and zirconium balls is 1:1~2:1.5~2. The ball milling time is 5~10 hours. After ball milling, the obtained slurry is dried at 80°C to obtain secondary ball milled dried powder.

[0079] Step 6: Granulation: Add deionized water and a polyvinyl alcohol solution with a concentration of 5% to 7% to the secondary ball-milled dried powder obtained in step 5 and mix evenly. The mass ratio of powder, deionized water and polyvinyl alcohol solution is 1:1 to 2:0.15 to 0.3. After mixing evenly, use a spray granulation device to spray granulate the obtained mixed slurry to obtain a dry powder.

[0080] Step 7: Molding: The dry powder obtained in step 6 is placed in a mold and dry-pressed to obtain a green body.

[0081] Step 8: Sintering: The green body obtained in step 7 is sintered at a temperature of 1560° C. in an air atmosphere for 8 hours to obtain the final resonator device.

[0082] Example 7

[0083] Step 1: Ingredients: CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3 and TiO2 are used as raw materials, according to the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n The raw materials SrCO3, CaCO3, La2O3, Al2O3 and TiO2 except CeO2 and Ga2O3 were mixed to obtain a mixed material.

[0084] Step 2: primary ball milling: ball mill the mixture prepared in step 1 with deionized water and zirconium balls. The mass ratio of the mixture, deionized water and zirconium balls is 1:1-2:1.5-2. The ball milling time is 5-10 hours. After ball milling, the ball mill is dried at 110°C and passed through a 60-mesh sieve to obtain a primary ball mill.

[0085] Step 3: Pre-calcination: Pre-calcine the primary ball mill material obtained in step 2 at 1470° C. for 3.5 hours to obtain pre-calcined powder.

[0086] Step 4: Sieve: Pass the powder obtained in step 3 through a 60-mesh sieve to obtain a powder with fine particles.

[0087] Step 5: Secondary ball milling: Add the sieved powder in Step 4 to the weighed CeO2 and Ga2O3 raw materials in Step 1, mix them evenly, and then perform secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixture, alcohol, and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, dry the obtained slurry at 80 °C to obtain the secondary ball milled and dried powder.

[0088] Step 6: Granulation: Add deionized water and a polyvinyl alcohol solution with a concentration of 5% - 7% to the secondary ball milled and dried powder obtained in Step 5, and mix them evenly. The mass ratio of the powder, deionized water, and polyvinyl alcohol solution is 1:1 - 2:0.15 - 0.3. After mixing evenly, use a spray granulation device to perform spray granulation on the obtained mixed slurry to obtain dry powder.

[0089] Step 7: Molding: Place the dry powder obtained in Step 6 into a mold and perform dry pressing molding to obtain a green body.

[0090] Step 8: Sintering: Sinter the green body obtained in Step 7 at a temperature of 1540 °C and in an air atmosphere for 9 hours to obtain the final resonator device.

[0091] Example 8

[0092] Step 1: Batching: Using CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3, and TiO2 as raw materials, batch according to the molar ratio of the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3 (x = 0.9, y = 0.98, z = 0.15, m = 0.005, n = 0.01). Mix the SrCO3, CaCO3, La2O3, Al2O3, and TiO2 raw materials except for CeO2 and Ga2O3 to obtain a mixture.

[0093] Step 2: Primary ball milling: Perform primary ball milling on the mixture prepared in Step 1 with deionized water and zirconium balls. The mass ratio of the mixture, deionized water, and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, dry the ball milled material at 11°C and pass through a 60-mesh sieve to obtain the primary ball milled material.

[0094] Step 3: Pre-sintering: Pre-sinter the primary ball milled material obtained in Step 2 at a temperature of 1480 °C for 3 hours to obtain the pre-sintered powder.

[0095] Step 4: Sieving: Pass the powder obtained in Step 3 through a 60-mesh sieve to obtain a powder with fine particles.

[0096] Step 5: Secondary ball milling: Add the sieved powder in Step 4 to the weighed CeO2 and Ga2O3 raw materials in Step 1, mix them evenly, and then perform secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixture, alcohol, and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, dry the obtained slurry at 80°C to obtain the secondary ball milled and dried powder.

[0097] Step 6: Granulation: Add deionized water and a polyvinyl alcohol solution with a concentration of 5% - 7% to the secondary ball milled and dried powder obtained in Step 5, and mix them evenly. The mass ratio of the powder, deionized water, and polyvinyl alcohol solution is 1:1 - 2:0.15 - 0.3. After mixing evenly, use a spray granulation device to spray granulate the obtained mixed slurry to obtain the dried powder.

[0098] Step 7: Molding: Place the dried powder obtained in Step 6 into a mold and perform dry pressing to form a green body.

[0099] Step 8: Sintering: Sinter the green body obtained in Step 7 at a temperature of 1550°C and in an air atmosphere for 6 hours to obtain the final resonator device.

[0100] For the resonator obtained through the above experimental steps, combine a network analyzer (Agilent Technologies E5071C) and the single - cavity test method to test the microwave dielectric properties of the resonator samples, and obtain the dielectric constant (ε r ), quality factor (Q), resonance frequency (f 25 ) at 25°C, and resonance frequency (f 85 ) at 85°C of each sample in the examples. According to the measured performance data, calculate the Q×f 25 value at 25°C, the frequency drift (Δf) between 85°C and 25°C of the resonator, and the frequency temperature coefficient (τ f ). The frequency temperature coefficient is calculated by the formula τ f = (f 85 - f 25 )(f 25 ×60).

[0101] For Examples 1 - 8, the raw material compositions and sintering processes for preparing the resonators are shown in Table 1:

[0102] Table 1 Specific formulations and sintering processes for preparing resonators in Examples 1 - 8

[0103]

[0104] For Examples 1 - 8, the microwave dielectric properties of the prepared resonators are shown in Table 2:

[0105] Table 2 Microwave dielectric properties of the resonators prepared in Examples 1-8

[0106]

[0107] The optimized solution in the examples is Example 3. The present invention is not limited to the above 8 specific examples. It should be noted that it is entirely feasible to obtain microwave dielectric ceramic resonators with excellent performance by appropriately adjusting the dopants and preparation processes, but these all fall within the scope of the present invention.

Claims

1. A SrTiO3-LaAlO3-based microwave dielectric ceramic with the chemical formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3, where 0.7 ≤ x ≤ 1.15, 0.98 ≤ y ≤ 1.01, 0.05 ≤ z ≤ 0.15; 0.001 ≤ m ≤ 0.01; 0.001 ≤ n ≤ 0.

015.

2. A resonator based on SrTiO3-LaAlO3 based microwave dielectric ceramics, characterized in that: The harmonic oscillator uses a microwave dielectric ceramic, and the chemical formula of the microwave dielectric ceramic is Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3, where 0.7 ≤ x ≤ 1.15, 0.98 ≤ y ≤ 1.01, 0.05 ≤ z ≤ 0.15; 0.001 ≤ m ≤ 0.01; 0.001 ≤ n ≤ 0.015; the sintering conditions of the harmonic oscillator are: in air, the sintering temperature is 1500°C to 1600°C; the resonance frequency is 2.4 to 2.6 GHz, the Q value is 17700 to 19800, and the temperature coefficient of resonance frequency is 0 ± 5 ppm / °C.

3. The preparation method of a resonator based on SrTiO3-LaAlO3-based microwave dielectric ceramics according to claim 2, characterized in that Including the following steps: Step 1: Batching: Using CeO2, Ga2O3, SrCO3, CaCO3, La2O3, Al2O3, and TiO2 as raw materials, batch according to the molar ratio of the chemical composition formula Sr (y-z) Ca z Ti 1-m Ce m O3-xLa 1-n Ga n AlO3, mix the raw materials of SrCO3, CaCO3, La2O3, Al2O3, and TiO2 except CeO2 and Ga2O3 to obtain a mixed material, where 0.7 ≤ x ≤ 1.15, 0.98 ≤ y ≤ 1.01, 0.05 ≤ z ≤ 0.15; 0.001 ≤ m ≤ 0.01; 0.001 ≤ n ≤ 0.015; the purity of each raw material > 99.5%; Step 2: Primary ball milling: The mixed material prepared in Step 1 is subjected to primary ball milling with deionized water and zirconium balls. The mass ratio of the mixed material, deionized water and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, the ball-milled material is dried at 110°C and sieved through a 60-mesh sieve to obtain the primary ball-milled material; Step 3: Pre-sintering: The primary ball-milled material obtained in Step 2 is pre-sintered at a temperature of 1300°C - 1500°C for 2 - 5 hours to obtain the pre-sintered powder; Step 4: Sieving: The powder obtained in Step 3 is sieved through a 60-mesh sieve to obtain a powder with fine particles; Step 5: Secondary ball milling: The powder sieved in Step 4 is added with the weighed CeO2 and Ga2O3 raw materials in Step 1 and mixed evenly, and then subjected to secondary ball milling with alcohol and zirconium balls. The mass ratio of the mixed material, alcohol and zirconium balls is 1:1 - 2:1.5 - 2. The ball milling time is 5 - 10 hours. After ball milling, the obtained slurry is dried at 80°C to obtain the dried powder of secondary ball milling; Step 6: Granulation: Deionized water and a polyvinyl alcohol solution with a concentration of 5% - 7% are added to the dried powder of secondary ball milling obtained in Step 5 and mixed evenly. The mass ratio of the powder, deionized water and polyvinyl alcohol solution is 1:1 - 2:0.15 - 0.

3. After mixing evenly, the obtained mixed slurry is spray granulated by a spray granulation device to obtain the dried powder; Step 7: Forming: The dried powder obtained in Step 6 is placed into a mold and dry-pressed to form a green body; Step 8: Sintering: The green body obtained in Step 7 is sintered at a temperature of 1500°C - 1600°C in an air atmosphere for 4 - 10 hours to obtain the final resonator device.

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