Medium-temperature sintered high-Q-value microwave dielectric ceramic material and preparation method thereof

Abstract

The invention relates to the technical field of ceramic materials, and discloses a medium-temperature sintered high-Q-value microwave dielectric ceramic material and a preparation method thereof, the medium-temperature sintered high-Q-value microwave dielectric ceramic material comprises a main phase ceramic, an oxide modifier and a sintering aid; the main phase ceramic is (1-x) CaTiO3-x Sm < 0.9 > Y < 0.1 > Al < 1 + y > O < 3 >; the oxide modifier is prepared from mwt% of CeO2, nwt% of MnO2, pwt% of La2O3 and qwt% of Nd2O3 according to the mass percent of the main phase ceramic; the sintering aid comprises three or more of SiO2, Al2O3, SrCO3, TiO2, ZrO2 and B2O3, the addition amount of the sintering aid accounts for zwt% of the main phase ceramic, and z is greater than or equal to 0.3 and less than or equal to 0.8. The ceramic material disclosed by the invention can be sintered compactly at 1250-1400 DEG C, the sintering heat preservation time is shortened, and the ceramic material has excellent microwave dielectric properties, is simple to prepare and has good repeatability.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic materials, and in particular to a medium-temperature sintered high-Q value microwave dielectric ceramic material and a preparation method thereof. Background Art

[0002] In recent years, with the development of microwave communication technology, especially the rapid iteration of 5G mobile communication technology, the research and application of microwave dielectric ceramic materials have been vigorously promoted, and have been widely used in the preparation of components such as dielectric resonators, dielectric filters and dielectric antennas. Ohsato et al. pointed out in the article "Forsterite ceramics for millimeterwave dielectrics" published in Journal of Electroceramics, Vol. 17, 2006, pp. 445-450 that the development direction of microwave dielectric ceramics includes high Q value and low ε for millimeter wave applications. r Materials, high Q value and high ε for base stations r Ceramics and high ε for miniaturized devices r Ceramics. It can be seen that suitable dielectric constant and high Q value are the basic requirements for microwave dielectric ceramic materials.

[0003] CaTiO 3 -ReAlO 3 (Re=La, Nd, Sm, Y) is an important high Q value medium dielectric constant material. This series of ceramics has good physical and mechanical properties, with a thermal expansion coefficient of 10ppm / ℃ and a strength of more than 150MPa. The invention patent with publication number CN105000884A discloses a microwave dielectric ceramic material and its preparation method and application, including ReAlO 3 The Quf value of the series of materials reaches 40000 GHz, but the sintering temperature is as high as 1550°C, which limits its industrial application scope. The invention patent with publication number CN108752016A discloses a microwave dielectric ceramic sintering aid and its preparation method. The sintering aid can reduce CaTiO 3 -LaAlO 3 The sintering temperature of the ceramic system was reduced from 1450℃ to 1280℃, but the Quf value of the material decreased significantly with the decrease of sintering temperature. At 1280℃, it was only 25000GHz. In the medium and high temperature material system with sintering temperature of 1200~1400℃, BaTi 4 O 9 and Ba 2 Ti 9 O 20Intermediate materials have similar dielectric properties, but these materials usually have a thermal expansion coefficient of 8ppm / ℃ and a bending strength of about 80-100MPa. The products prepared are at great risk of cracking when subjected to thermal shock or external force impact. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a medium-temperature sintered high-Q value microwave dielectric ceramic material and a preparation method thereof. The material can achieve densification sintering within a medium temperature range (1250-1400°C), and at the same time has a near-zero frequency temperature coefficient, high strength and thermal expansion coefficient. The preparation method has simple process, good repeatability, low energy consumption, and is suitable for mass industrial production and application.

[0005] The purpose of the present invention is achieved through the following technical solutions: In the first aspect, the present invention provides a medium-temperature sintered high-Q value microwave dielectric ceramic material, comprising a main phase ceramic, an oxide modifier and a sintering aid; the main phase ceramic is (1-x)CaTiO 3 -x Sm 0.9 Y 0.1 Al 1+y O 3 , wherein 0.2≤x≤0.4, -0.05≤y≤0.03; in terms of mass percentage of the main phase ceramic, the oxide modifier comprises mwt% CeO 2 、nwt%MnO 2 , pwt%La 2 O 3 and qwt% Nd 2 O 3 , wherein 0≤m≤0.5, 0≤n≤0.3, 0≤p≤0.5, 0≤q≤0.3, and m, n, p, q are not all 0 at the same time; the sintering aid includes SiO 2 、Al 2 O 3 、SrCO 3 、TiO 2 、ZrO 2 and B 2 O 3 For three or more of the above, the amount of sintering aid added is zwt% of the main phase ceramic, 0.3≤z≤0.8.

[0006] Preferably, the main phase ceramic is (1-x)CaTiO 3 -x Sm 0.9 Y 0.1 Al 1+y O 3 , where 0.2≤x≤0.4, 0≤y≤0.03.

[0007] Preferably, the main phase ceramic is (1-x)CaTiO 3 -x Sm 0.9 Y 0.1 Al 1+y O 3 , where 0.2≤x≤0.4, 0<y≤0.03.

[0008] Preferably, the oxide modifier comprises mwt% CeO 2 、nwt%MnO 2 、pwt%La 2 O 3 and qwt% Nd 2 O 3 , where 0≤m≤0.5, 0≤n≤0.3, 0≤p≤0.5, 0≤q≤0.3, and at most one of m, n, p, q is 0.

[0009] Preferably, the composition of the sintering aid is awt% SiO 2 -bwt%Al 2 O 3 -cwt% SrCO 3 -dwt% ZrO 2 -ewt%TiO 2 -fwt%B 2 O 3 , where: 30≤a≤45, 20≤b≤35, 20≤c≤30, 0≤d≤5, 0≤e≤5, 0≤f≤15, and a+b+c+d+e+f=100.

[0010] Preferably, the sintering aid is a raw material SiO 2 、Al 2 O 3 、SrCO 3 、TiO 2 、ZrO 2 and H 3 BO 3 The molten mixture of three or more of the above at 1450-1550° C. is cooled to obtain the product.

[0011] In a second aspect, the present invention also provides a method for preparing a medium-temperature sintered high-Q value microwave dielectric ceramic material, comprising the following steps: S1, according to (1-x)CaTiO 3 -x Sm 0.9 Y 0.1 Al 1+y O 3 Weigh the raw material CaCO in the stoichiometric ratio 3 、TiO2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , adding water to wet mix and drying, sieving the mixture, and then calcining to synthesize the main crystal phase to obtain the main phase base material; S2, the raw material SiO 2 、Al 2 O 3 、SrCO 3 、TiO 2 、ZrO 2 and H 3 BO 3 Three or more of the above are mixed, anhydrous ethanol is added to wet-mix the mixture, and then the mixture is dried, the mixture is sieved, and then melted, and then the melt is quenched to obtain a sintering aid; S3, mixing the main phase base material, oxide modifier and sintering aid, adding water to wet mix and then drying; S4. Add a binder, press and sinter to obtain a microwave dielectric ceramic material.

[0012] Preferably, in S1, the wet mixing is: the material-water mass ratio is 1:1.5-2.5, and the wet mixing time is 16-24h.

[0013] Preferably, in S1, the calcination is: heating to 1200-1270°C and maintaining the temperature for calcination for 2-4 hours.

[0014] Preferably, in S2, the wet mixing is: the material-water mass ratio is 1:1.0-2.0, and the wet mixing time is 18-24h.

[0015] Preferably, in S2, the melting is: firstly heating from room temperature to 1000°C at a heating rate of 5-8°C / min, then heating to 1450-1550°C at a heating rate of 1-3°C / min, and maintaining the melting for 1-2h.

[0016] Preferably, in S2, according to awt% SiO 2 -bwt%Al 2 O 3 -cwt% SrCO 3 -dwt% ZrO 2 -ewt%TiO 2 -fwt%B 2 O 3 Weigh the raw material SiO in the stoichiometric ratio 2 、Al 2 O 3 、SrCO3 、TiO 2 、ZrO 2 and H 3 BO 3 , where: 30≤a≤45, 20≤b≤35, 20≤c≤30, 0≤d≤5, 0≤e≤5, 0≤f≤15, and a+b+c+d+e+f=100.

[0017] Preferably, in S2, the melt is quenched in water at a temperature of 20-30°C from room temperature.

[0018] Preferably, in S3, the wet mixing is: the material-water mass ratio is 1:1.0-1.5, and the wet mixing time is 12-18 hours.

[0019] Preferably, in S4, the amount of the binder added is 2-5wt% of the ceramic material obtained in step S3; after the binder is added, the mixture is mixed, granulated, pressed and sintered in sequence to obtain a microwave dielectric ceramic material.

[0020] Preferably, in S4, the pressing is performed to form an embryo body according to the shape of the final product; the pressing pressure is 100-500 MPa.

[0021] Preferably, in S4, the sintering temperature is 1250-1530° C. and the sintering time is 4-8 hours.

[0022] Preferably, in S4, the sintering temperature is 1250-1400° C. and the sintering time is 4-8 hours.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) In (1-x)CaTiO 3 -x Sm 0.9 Y 0.1 Al 1+y O 3 In the main phase ceramics, Sm 3+ and Y 3+ Occupancy of Ca 2+ Node location, Al 3 + Occupy Ti 4+ The node position forms a solid solution structure, which can obtain excellent dielectric properties. 3+ The excessive non-stoichiometric formula design can play the role of acceptor dopant, which can better inhibit the Ti 4+ Reduced to Ti 3+ , thereby reducing the dielectric loss caused by vacancies.

[0024] (2) Oxide modifier CeO 2and MnO 2 Can be respectively through Ce 4+ Convert to Ce 3+ and Mn 4+ Converted to Mn 3+ The price change process further inhibits Ti 4+ Reduced to Ti 3+ , the same as La 2 O 3 and / or Nd 2 O 3 Adding them together can also increase the grain boundary density, thereby reducing the extrinsic loss of the material.

[0025] (3) During the sintering process, the sintering aid forms a liquid phase to infiltrate the main phase grains, promote the rearrangement of the powder particles, and achieve a compact spatial stacking effect at a lower temperature; on the other hand, it can also promote the dissolution of small particles with sharp edges in the green body in the liquid phase, and quickly realize crystallization on the surface of coarse particles through liquid phase diffusion, significantly accelerating the reaction process. Therefore, the ceramic material prepared by the present invention can be densely sintered at 1250-1400°C and shorten the sintering insulation time. It has certain low energy consumption advantages and can shorten the production cycle, and has great practical value.

[0026] (4) The ceramic material obtained by the present invention can be sintered to a compact size at 1250-1400°C and has excellent microwave dielectric properties (ε r =41-47), the quality factor Q×f value reaches above 27000GHz, the temperature coefficient τ f Nearly zero adjustable. Moreover, the preparation process is simple, with good repeatability, low energy consumption, and low raw material cost. It can be used to prepare dielectric resonators for base stations, dielectric filters for 5G small base stations and other products. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the microwave dielectric ceramic material prepared in Example 10.

[0028] Figure 2 This is a scanning electron microscope image of the microwave dielectric ceramic material prepared in Example 19.

[0029] Figure 3 This is a scanning electron microscope image of the microwave dielectric ceramic material prepared in Example 21. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is described below with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0031] Example 1 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO3 -0.3Sm 0.9 Y 0.1 Al 0.96 O 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0032] S2. Add deionized water to the main phase base material at a material-water mass ratio of 1:1.2, wet mix the materials for 14 hours, and then dry them at 120° C. to obtain a ceramic material.

[0033] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter and keep warm at 1530° C. for 5 hours to obtain a microwave dielectric ceramic material.

[0034] Example 2 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm 0.9 Y 0.1 Al 0.98 O 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0035] S2. Add deionized water to the main phase base material at a material-water mass ratio of 1:1.2, wet mix the materials for 14 hours, and then dry them at 120° C. to obtain a ceramic material.

[0036] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter and keep warm at 1530° C. for 5 hours to obtain a microwave dielectric ceramic material.

[0037] Example 2 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm 0.9 Y 0.1 AlO 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0038] S2. Add deionized water to the main phase base material at a material-water mass ratio of 1:1.2, wet mix the materials for 14 hours, and then dry them at 120° C. to obtain a ceramic material.

[0039] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter and keep warm at 1530° C. for 5 hours to obtain a microwave dielectric ceramic material.

[0040] Example 4 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm 0.9 Y 0.1 Al 1.02 O 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3, add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0041] S2. Add deionized water to the main phase base material at a material-water mass ratio of 1:1.2, wet mix the materials for 14 hours, and then dry them at 120° C. to obtain a ceramic material.

[0042] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter and keep warm at 1530° C. for 5 hours to obtain a microwave dielectric ceramic material.

[0043] Example 5 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm 0.9 Y 0.1 Al 1.04 O 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0044] S2. Add deionized water to the main phase base material at a material-water mass ratio of 1:1.2, wet mix the materials for 14 hours, and then dry them at 120° C. to obtain a ceramic material.

[0045] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter and keep warm at 1530° C. for 5 hours to obtain a microwave dielectric ceramic material.

[0046] Example 6 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm 0.9 Y0.1 AlO 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0047] S2, the main phase base material and oxide modifier (0.3wt% CeO 2 ) The ingredients were prepared according to the mass ratio in Table 1, deionized water was added at a material-water mass ratio of 1:1.2, the wet mixing was performed for 14 hours and then the mixture was dried at 120° C. to obtain a ceramic material.

[0048] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter it at 1500° C. for 5 hours, and obtain a microwave dielectric ceramic material.

[0049] Example 7 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm 0.9 Y 0.1 AlO 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0050] S2, the main phase base material and oxide modifier (0.3wt% CeO 2 +0.4wt%La 2 O 3) The ingredients were prepared according to the mass ratio in Table 1, deionized water was added at a material-water mass ratio of 1:1.2, the wet mixing was performed for 14 hours and then the mixture was dried at 120° C. to obtain a ceramic material.

[0051] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter it at 1500° C. for 5 hours, and obtain a microwave dielectric ceramic material.

[0052] Example 8 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm 0.9 Y 0.1 AlO 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0053] S2, the main phase base material and oxide modifier (0.15wt% CeO 2 +0.3wt%MnO 2 +0.25wt%La 2 O 3 +0.3wt%Nd 2 O 3 ) The ingredients were prepared according to the mass ratio in Table 1, deionized water was added at a material-water mass ratio of 1:1.2, the wet mixing was performed for 14 hours and then the mixture was dried at 120° C. to obtain a ceramic material.

[0054] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter it at 1500° C. for 5 hours, and obtain a microwave dielectric ceramic material.

[0055] Example 9 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm0.9 Y 0.1 AlO 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0056] S2, the main phase base material and oxide modifier (0.15wt% CeO 2 +0.1wt%MnO 2 +0.25wt%La 2 O 3 +0.3wt%Nd 2 O 3 ) The ingredients were prepared according to the mass ratio in Table 1, deionized water was added at a material-water mass ratio of 1:1.2, the wet mixing was performed for 14 hours and then the mixture was dried at 120° C. to obtain a ceramic material.

[0057] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter it at 1500° C. for 5 hours, and obtain a microwave dielectric ceramic material.

[0058] Example 10 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm 0.9 Y 0.1 AlO 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0059] S2, the main phase base material and oxide modifier (0.15wt% CeO 2 +0.3wt%MnO 2 +0.25wt%La 2 O 3 +0.2wt%Nd 2 O 3 ) The ingredients were prepared according to the mass ratio in Table 1, deionized water was added at a material-water mass ratio of 1:1.2, the wet mixing was performed for 14 hours and then the mixture was dried at 120° C. to obtain a ceramic material.

[0060] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter it at 1500° C. for 5 hours, and obtain a microwave dielectric ceramic material.

[0061] Embodiment 11 The preparation of microwave dielectric ceramic materials includes the following steps: S1, according to 0.7CaTiO 3 -0.3Sm 0.9 Y 0.1 Al 1.02 O 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0062] S2, the main phase base material and oxide modifier (0.15wt% CeO 2 +0.3wt%MnO 2 +0.25wt%La 2 O 3 +0.2wt%Nd 2 O 3 ) The ingredients were prepared according to the mass ratio in Table 1, deionized water was added at a material-water mass ratio of 1:1.2, the wet mixing was performed for 14 hours and then the mixture was dried at 120° C. to obtain a ceramic material.

[0063] S3. Add 3 wt % polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter it at 1500° C. for 5 hours, and obtain a microwave dielectric ceramic material.

[0064] Table 1 The volume density of the sintered ceramic samples was determined by the Archimedean drainage method, and the dielectric constant ε was measured by the Agilent 8719ET network analyzer according to the Hakki-Coleman resonant cavity method. r And Q×f value, the frequency temperature coefficient is tested in the temperature range of 25~85℃, and according to the formula τ f =(f 85 -f 25 ) / (f 25 ×60) is calculated and determined, where f 85 and f 25 are the center frequencies of the samples at 85° C. and 25° C. respectively. The test data of Examples 1-11 are shown in Table 2.

[0065] Table 2 Examples 12-21 The preparation of medium temperature sintered high Q value microwave dielectric ceramic material includes the following steps: S1, according to (1-x)CaTiO 3 -xSm 0.9 Y 0.1 Al 1+y O 3 The raw material CaCO 3 、TiO 2 、Sm 2 O 3 , Y 2 O 3 and Al 2 O 3 , add deionized water at a material-water mass ratio of 1:1.8, wet mix for 24 hours and then dry at 120°C, pass the dried mixture through a 40-mesh sieve, put it into an alumina crucible, calcine at 1230°C for 4 hours to synthesize the main crystalline phase, grind and pass through a 40-mesh sieve as the main phase base material for later use.

[0066] S2, according to awt%SiO 2 -bwt%Al 2 O 3 -cwt% SrCO 3-dwt% ZrO 2 -ewt%TiO 2 -fwt%B 2 O 3 The raw material SiO 2 、Al 2 O 3 、SrCO 3 、TiO 2 、ZrO 2 and H 3 BO 3 , add anhydrous ethanol at a mass ratio of 1:1.5 between the mixture and anhydrous ethanol, dry at 80°C after wet mixing for 18 hours, pass the dried mixture through a 250-mesh sieve, put it into a crucible, heat it from room temperature to 1000°C at a rate of 5°C / min, then heat it to 1550°C at a rate of 3°C / min, keep it warm for 1 hour, then pour the melt into deionized water at room temperature to quench it, crush and grind the obtained glass slag, and pass it through a 250-mesh sieve to obtain a sintering aid for use.

[0067] S3, the main phase base material, oxide modifier (mwt% CeO 2 +nwt%MnO 2 +pwt%La 2 O 3 +qwt%Nd 2 O 3 ) and sintering aids were mixed according to the mass ratio in Table 3, deionized water was added at a material-water mass ratio of 1:1.2, and the wet mixing was carried out for 14 hours and then dried at 120°C to obtain a ceramic material.

[0068] S4. Add 3 wt% polyvinyl alcohol (PVA) binder to the ceramic material for granulation, press it into a cylindrical body with a diameter of 20 mm and a thickness of 8 to 9 mm at 100 MPa, sinter and keep warm at 1250 to 1400°C for 5 hours to obtain a medium-temperature sintered high-Q value microwave dielectric ceramic material.

[0069] Table 3 Table 4 The volume density of the sintered ceramic samples was determined by the Archimedean drainage method, and the dielectric constant ε was measured by the Agilent 8719ET network analyzer according to the Hakki-Coleman resonant cavity method. r And Q×f value, the frequency temperature coefficient is tested in the temperature range of 25~85℃, and according to the formula τ f =(f 85 -f 25 ) / (f 25×60) is calculated and determined, where f 85 and f 25 are the center frequencies of the samples at 85° C. and 25° C. respectively. The test data of Examples 12-21 are shown in Table 5.

[0070] Table 5 serial number Sintering temperature(℃) <![CDATA[Porcelain body density (g / cm 3 )]]> <![CDATA[ε r ]]> Q×f(GHz) <![CDATA[τ f (ppm / ℃)]]> Example 12 1375 4.79 44.75 38400 1.8 Example 13 1375 4.78 44.13 42500 4.1 Embodiment 14 1350 4.81 44.8 41000 3.2 Embodiment 15 1350 4.78 42.8 36500 -5.3 Example 16 1375 4.78 45.1 36450 6.1 Embodiment 17 1375 4.69 41.6 32000 -4.2 Embodiment 18 1325 4.78 44.2 35300 4.7 Embodiment 19 1350 4.79 43.4 39520 0.2 Embodiment 20 1300 4.71 43.8 30200 2.6 Embodiment 21 1250 4.64 42.1 27450 3.8 As shown in Table 1, the microwave dielectric ceramic materials in Examples 1-4 contain only the main phase ceramic (1-x)CaTiO 3 -xSm 0.9 Y 0.1 Al 1+y O 3 , where Al 3+ (1+y) is a non-stoichiometric formula design. When the value of y changes from negative to positive, the Q×f value of the ceramic material mainly shows a trend of first increasing and then decreasing, as shown in Table 2. 3+ The non-stoichiometric formula design (y>0) can significantly improve the Q×f value of the material. In addition, the microwave dielectric ceramic materials in Examples 6-11 contain only the main phase ceramic and the oxide modifier, and the oxide modifier includes mwt% CeO 2 、nwt%MnO 2 、pwt%La 2 O 3 ,qwt%Nd 2 O 3 As shown in Table 2, adding oxide modifiers to the main phase ceramics can improve the Q×f value of the material, and the type and ratio of metal oxides in the oxide modifiers will also affect the Q×f value, but it is still better than the Q×f value of the material without the addition of oxide modifiers. Sintering at 1500°C can also achieve a higher density and dielectric constant.

[0071] As shown in Table 3 and Table 4, the microwave dielectric ceramic materials in Examples 12-21 and Examples 1-4 contain a main phase ceramic, an oxide modifier and a sintering aid. As shown in Table 5, the microwave dielectric ceramic materials prepared by adding the sintering aid have a significantly lower sintering densification temperature and have a relatively high Q×f value and a near-zero adjustable temperature coefficient. Figure 2 and Figure 3 As shown in FIG. 19 and FIG. 21, the microwave dielectric ceramic materials obtained in Example 19 and Example 21 can obtain a fine-grained and dense microstructure at a lower temperature. Figure 1 The microwave dielectric ceramic material obtained in Example 10 shown in the figure has larger grains and lower relative density. Figure 3 Relative to Figure 2The grains of the ceramic material are smaller because the sintering temperature of Example 21 is lower, but in fact the porosity between the grains is also relatively high. Therefore, the Q×f value of the material of Example 21 is lower than that of Example 19, but it is still higher than the Q×f value of the ceramic material with a sintering temperature of 1250°C in the prior art.

[0072] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the specification of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A medium-temperature sintered high-Q value microwave dielectric ceramic material, characterized in that: It includes a main phase ceramic, an oxide modifier and a sintering aid; the main phase ceramic is (1- x ) CaTiO3- x Sm 0.9 Y 0.1 Al 1+y O3, where 0.2≤ x ≤0.4, -0.05≤ y ≤0.03; Calculated by mass percentage of the main phase ceramic, the oxide modifier includes m wt%CeO2, n wt% of MnO2, p wt% La2O3 and q wt% Nd2O3, where 0≤ m ≤0.5,0≤ n ≤0.3,0≤ p ≤0.5,0≤ q ≤0.3, and m , n , p , q The sintering aid includes three or more of SiO2, Al2O3, SrCO3, TiO2, ZrO2 and B2O3, and the amount of the sintering aid added is 10% of the main phase ceramic. z wt%,0.3≤ z ≤0.

8.

2. The medium-temperature sintered high-Q value microwave dielectric ceramic material according to claim 1, characterized in that: The composition of the sintering aid is a wt% SiO2- b wt% Al2O3- c wt% SrCO3- d wt% ZrO2- e wt% TiO2- f wt% B2O3, of which: 30≤ a ≤45,20≤ b ≤35, 20≤ c ≤30,0≤ d ≤5,0≤ e ≤5,0≤ f ≤15, and a + b + c + d + e + f =100.

3. The medium-temperature sintered high-Q value microwave dielectric ceramic material according to claim 1 or 2, characterized in that: The sintering aid is prepared by cooling a molten mixture of three or more of the raw materials SiO2, Al2O3, SrCO3, TiO2, ZrO2 and H3BO3 at 1450-1550°C.

4. A method for preparing a medium-temperature sintered high-Q value microwave dielectric ceramic material as claimed in any one of claims 1 to 3, characterized in that: The steps include: S1, press (1- x ) CaTiO3- x Sm 0.9 Y 0.1 Al 1+y The raw materials CaCO3, TiO2, Sm2O3, Y2O3 and Al2O3 are weighed in a stoichiometric ratio in O3, wet mixed with water and then dried, the mixed material is sieved, and then calcined to synthesize the main crystalline phase to obtain the main phase base material; S2, mixing three or more of the raw materials SiO2, Al2O3, SrCO3, TiO2, ZrO2 and H3BO3 in proportion, adding anhydrous ethanol to wet-mix and drying, sieving the mixture, melting it, and then quenching the melt to obtain a sintering aid; S3, mixing the main phase base material, oxide modifier and sintering aid, adding water to wet mix and then drying; S4. Add a binder, press and sinter to obtain a microwave dielectric ceramic material.

5. The method for preparing a medium-temperature sintered high-Q value microwave dielectric ceramic material according to claim 4, characterized in that: In S1, the wet mixing is: the mass ratio of material to water is 1:1.5-2.5, and the wet mixing time is 16-24h.

6. The method for preparing a medium-temperature sintered high-Q value microwave dielectric ceramic material according to claim 4 or 5, characterized in that: In S1, the calcination is: heating to 1200-1270°C and maintaining the temperature for calcination for 2-4 hours.

7. The method for preparing a medium-temperature sintered high-Q value microwave dielectric ceramic material according to claim 4, characterized in that: In S2, the wet mixing is: the mass ratio of material to water is 1:1.0-2.0, and the wet mixing time is 18-24h.

8. The method for preparing a medium-temperature sintered high-Q value microwave dielectric ceramic material according to claim 4 or 7, characterized in that: In S2, the melting is: firstly heating from room temperature to 1000°C at a heating rate of 5-8°C / min, then heating to 1450-1550°C at a heating rate of 1-3°C / min, and maintaining the melting for 1-2h.

9. The method for preparing a medium-temperature sintered high-Q value microwave dielectric ceramic material according to claim 4 or 7, characterized in that: In S2, according to a wt% SiO2- b wt% Al2O3- c wt% SrCO3- d wt% ZrO2- e wt% TiO2- f wt% Stoichiometric ratio in B2O3 Weigh the raw materials SiO2, Al2O3, SrCO3, TiO2, ZrO2 and H3BO3, where: 30≤ a ≤45,20≤ b ≤35, 20≤ c ≤30,0≤ d ≤5,0≤ e ≤5,0≤ f ≤15, and a + b + c + d + e + f =100.

10. The method for preparing a medium-temperature sintered high-Q value microwave dielectric ceramic material according to claim 4, characterized in that: In S3, the wet mixing is: the mass ratio of material to water is 1:1.0-1.5, and the wet mixing time is 12-18 hours.

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