Ltcf phase shifter composite gyromagnetic ferrite substrate material and method of manufacturing the same

Abstract

The application discloses a composite gyromagnetic ferrite substrate material for an LTCF phase shifter and belongs to the technical field of electronic ceramic materials. 4+ 3+ 3+ The main LiZn ferrite is selected from Ti 4+ , Mn 3+ , Bi 3+ ion substituted iron-deficient formula, which ensures low-temperature sintering and has high saturation magnetization and low ferromagnetic resonance line width; the auxiliary SrM ferrite is selected from micro-nano structure particles with high Curie temperature, the SrM ferrite with the structure has high sintering activity, and is beneficial to forming a multiple dense microstructure mainly with fine grains in the low-temperature sintering process, so that the material has high residual magnetism ratio and high saturation magnetization.

Description

Technical Field

[0001] This invention belongs to the field of electronic ceramic materials technology, specifically relating to a composite ferrite substrate material for LTCF phase shifters and its preparation method. Background Technology

[0002] Low-temperature co-fired ferrite (LTCF) technology, with its excellent electrical, thermal, mechanical, and processing characteristics, provides an effective solution for the miniaturization and high integration of microwave ferrite devices. As a key substrate material for X-Ka band LTCF phase shifters, LiZn gyromagnetic ferrite presents a pressing problem: how to meet the requirements of low-temperature sintering (<960℃) while simultaneously achieving excellent comprehensive gyromagnetic properties (high saturation magnetization, high remanence, low ferromagnetic resonance linewidth, and high Curie temperature).

[0003] Currently, research on the low-temperature sintering and gyromagnetic properties of LiZn ferrite mainly focuses on ion substitution and low-melting-point oxide doping modification. Patent application CN202110324931.7 discloses a high-saturation magnetization, low-temperature sintered LiZn ferrite material and its preparation method, which uses Zr... 4+ Ion partial substitution of Zn in LiZn ferrite 2+ The material obtained by sintering at 925℃ using ions to reduce the ferromagnetic resonance linewidth has the following properties: specific saturation magnetization of 102.4 emu / g, ferromagnetic resonance linewidth of 205 Oe, and remanence ratio of 0.82. This method produces a material with a relatively high ferromagnetic resonance linewidth, which is detrimental to reducing the insertion loss of the phase shifter, and the low remanence ratio is not conducive to increasing the phase shift. Furthermore, no reports have been found regarding Curie temperature. Patent application CN201811197231.0 discloses a low-temperature sintering, low-loss LiZn ferrite material and its preparation method, which involves multi-element ion doping (Bi... 3+ Ions, V 5+ Ions, Ti 4+The method uses ions to activate the ferrite lattice, achieving low-temperature sintering while reducing microwave loss. The properties of the material sintered at 900℃ are as follows: saturation magnetization 4335 Gs, ferromagnetic resonance linewidth 159 Oe, remanence ratio 0.88. The ferromagnetic resonance linewidth of the material prepared by this method is still relatively high, and there are no reports related to Curie temperature. “Renquan Wang, Tingchuan Zhou, Zhiyong Zhong. Low-temperature processing of LiZn-based ferrite ceramics by co-doping of V2O5 and Sb2O3: Composition, microstructure and magnetic properties[J]. Journal of Materials Science & Technology, 2022, 99(04): 1-8.” The article improves the microstructure of LiZn ferrite by co-doping with trace amounts of V2O5 and Sb2O3, thereby reducing the ferromagnetic resonance linewidth and increasing the specific saturation magnetization. A LiZn ferrite material with a specific saturation magnetization of 82.51 emu / g, a remanence ratio of 0.85, and a ferromagnetic resonance linewidth of 153.8 Oe was obtained by sintering at 920℃. However, the ferromagnetic resonance linewidth of the material prepared by this method is still relatively large, and there are no reports on the Curie temperature. In summary, in order to meet the requirements of miniaturization and high integration, a better solution is urgently needed to improve the comprehensive performance indicators (high saturation magnetization, high remanence ratio, high Curie temperature, low ferromagnetic resonance linewidth, etc.) of gyromagnetic ferrite substrate materials for LTCF phase shifters. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by proposing a composite ferrite substrate material for LTCF phase shifters and its preparation method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A composite gyromagnetic ferrite substrate material for LTCF phase shifters is prepared by low-temperature co-firing of the main material LiZn ferrite (LZTMBF) and the auxiliary material SrM. Firstly, the main material LiZn ferrite is selected from Ti... 4+ Mn 3+ Bi 3+The ion-substituted iron-deficient formulation ensures both high saturation magnetization and low ferromagnetic resonance linewidth while maintaining low-temperature sintering. Secondly, the auxiliary material SrM ferrite is selected from micro-nano structured particles (regular hexagonal flakes, radial diameter 1-2 μm, thickness 30-50 nm) with high Curie temperature. This structure of SrM ferrite has high sintering activity, which is conducive to the formation of multiple dense microstructures dominated by fine grains during low-temperature sintering, ensuring that the material has a high remanence ratio and high saturation magnetization. Finally, a small amount of low-melting-point Bi2O3 additive is added. The main material, LiZn ferrite, has the following composition: Li₂CO₃ 11.65–12.33 mol%, ZnO 17.61–22.18 mol%, TiO₂ 8.22–13.31 mol%, Mn₃O₄ 1.85–1.96 mol%, Fe₂O₃ 50.93–59.79 mol%, Bi₂O₃ 0.08–0.09 mol%. The auxiliary material, strontium ferrite, has the following composition: Fe(NO₃)₃ 15.11–15.36 mol%, Sr(NO₃)₂ 2.19–3.78 mol%, NaOH 81.11–82.44 mol%. The content of the auxiliary material, strontium ferrite, relative to the main material, LiZn ferrite, is 1–5 wt.%.

[0007] A method for preparing a composite gyromagnetic ferrite substrate material for an LTCF phase shifter includes the following steps:

[0008] Step 1, Pre-fired material preparation:

[0009] 1.1 Using analytically pure lithium carbonate (LiCO3), zinc oxide (ZnO), titanium dioxide (TiO2), manganese tetroxide (Mn3O4), ferric oxide (Fe2O3), and bismuth trioxide (Bi2O3) as raw materials, the raw materials were weighed according to the following proportions: Li2CO3 11.65–12.33 mol%, ZnO 17.61–22.18 mol%, TiO2 8.22–13.31 mol%, Mn3O4 1.85–1.96 mol%, Fe2O3 50.93–59.79 mol%, Bi2O3 0.08–0.09 mol%. The raw materials were then transferred to the stainless steel ball mill jar of a planetary ball mill and wet-milled for 3–5 hours to obtain a primary slurry.

[0010] 1.2 After drying and sieving the primary slurry obtained in step 1.1, pre-calcine it in an oxygen furnace at 800-850℃ for 1.5-2.5 hours. After cooling to room temperature in the furnace, remove it to obtain the pre-calcined main material.

[0011] Step 2, Secondary ball milling:

[0012] After sieving the main pre-calcined material obtained in step 1, add 1-5 wt.% of auxiliary material and 2-4 wt.% of Bi2O3 equivalent to the added auxiliary material. Put the resulting mixture into a planetary ball mill for secondary ball milling for 5-8 hours. After drying the obtained secondary slurry, composite ferrite abrasive can be obtained.

[0013] Step 3: Shaping and sintering:

[0014] 3.1 After passing the composite ferrite abrasive obtained in step 2 through an 80-mesh sieve, add 8-12 wt.% polyvinyl alcohol (PVA) binder equivalent to the powder mass to granulate, and then press it into a green sample using a hydraulic press.

[0015] 3.2 The green sample obtained in step 3.1 is placed in a sintering furnace and heated to 910-930°C at a rate of 2°C / min. The temperature is held for 2 hours. After sintering, the sample is naturally cooled to room temperature in the furnace to obtain the composite ferrite substrate material.

[0016] The preparation process of the excipients in step 2 is as follows: Fe(NO3)3, Sr(NO3)2, and NaOH raw materials are weighed according to the ratio of "Fe(NO3)3 15.11-15.36 mol%, Sr(NO3)2 2.19-3.78% mol%, NaOH 81.11-82.44 mol%"; the weighed Fe(NO3)3 and Sr(NO3)2 are added to deionized water to prepare the desired solution. A salt solution was prepared by adding weighed NaOH to deionized water. The alkaline solution was added dropwise to the salt solution, and the resulting solid-liquid mixture was transferred to a reactor. The temperature was raised to 220°C at an initial pressure of 1.5 MPa and a heating rate of 1°C / min, and then held for 2 hours. After cooling to room temperature in the furnace, the mixed slurry was removed, filtered, washed, and dried to obtain the auxiliary material.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1. The LiZn ferrite selected in this invention is processed by Ti... 4+ Mn 3+ Bi 3+ Multi-ion co-substitution can reduce magnetocrystalline anisotropy and improve ferromagnetic resonance linewidth while ensuring low-temperature sintering. The selected auxiliary material, SrM ferrite, has a high Curie temperature; two-phase composite control yielded a sample with both low ferromagnetic resonance linewidth and high Curie temperature. Furthermore, by treating the LiZn ferrite with an oxygen atmosphere, Fe... 2+ The generation of ions optimizes the magnetic loss of the material.

[0019] 2. The SrM ferrite material of this invention is selected from micro-nano structured particles (regular hexagonal flakes, radial diameter 1-2 μm, thickness 30-50 nm) with high Curie temperature. This structure of SrM ferrite has high low-temperature sintering activity. During the low-temperature sintering process, SrM ferrite mainly stays at the grain boundaries, which is conducive to the formation of a multi-layered dense microstructure dominated by fine grains, ensuring that the material has a high remanence ratio and high saturation magnetization.

[0020] 3. The composite gyromagnetic ferrite substrate material for LTCF phase shifters prepared by this invention, in addition to having a low co-sintering temperature (910–930°C), also possesses excellent gyromagnetic properties: high saturation magnetization (4πM). s The fabricated ferromagnetic ferrite substrate material exhibits characteristics such as >3600Gs, low ferromagnetic resonance linewidth (ΔH@9.3GHz<120Oe), high remanence ratio (Br / Bs≥0.88), and high Curie temperature (Tc>320℃). It meets the requirements of the LTCF process and possesses the excellent magnetic properties of key substrate materials needed for phase shifters. Attached Figure Description

[0021] Figure 1 SEM images of the composite ferrite samples prepared for comparison.

[0022] Figure 2 This is a SEM image of the composite ferrite sample prepared in Example 1. Detailed Implementation

[0023] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0024] Example 1

[0025] Step 1, Pre-fired material preparation:

[0026] 1.1 Using analytically pure lithium carbonate (LiCO3), zinc oxide (ZnO), titanium dioxide (TiO2), manganese tetroxide (Mn3O4), ferric oxide (Fe2O3), and bismuth trioxide (Bi2O3) as raw materials, the raw materials were weighed according to the following ratio: Li2CO3 11.98 mol%, ZnO 19.96 mol%, TiO2 10.84 mol%, Mn3O4 1.9 mol%, Fe2O3 55.24 mol%, Bi2O3 0.08 mol%. The raw materials were then transferred to the stainless steel ball mill jar of a planetary ball mill and wet-milled for 4 hours to obtain a primary slurry.

[0027] 1.2 After drying and sieving the primary slurry obtained in step 1.1, it is pre-calcined in an oxygen furnace at 820°C for 2 hours. After cooling to room temperature in the furnace, it is taken out to obtain the main pre-calcined material.

[0028] Step 2, Secondary ball milling:

[0029] After sieving the main pre-calcined material obtained in step 1, add auxiliary materials equivalent to 2 wt.% of the main pre-calcined material and Bi2O3 equivalent to 3 wt.% of the added auxiliary materials. Put the resulting mixture into a planetary ball mill for secondary ball milling for 6 hours. After drying the resulting secondary slurry, composite ferrite abrasive can be obtained.

[0030] Step 3: Shaping and sintering:

[0031] 3.1 After passing the composite ferrite abrasive obtained in step 2 through an 80-mesh sieve, add 10 wt.% of polyvinyl alcohol (PVA) binder equivalent to the powder mass to granulate, and then press it into a green sample using a hydraulic press.

[0032] 3.2 The green sample obtained in step 3.1 is placed in a sintering furnace and heated to 920°C at a rate of 2°C / min. The temperature is held for 2 hours. After sintering, the sample is naturally cooled to room temperature in the furnace to obtain the composite gyromagnetic ferrite substrate material.

[0033] The preparation process of the excipients in step 2 is as follows: Fe(NO3)3, Sr(NO3)2, and NaOH raw materials are weighed according to the ratio of "Fe(NO3)3 15.23 mol%, Sr(NO3)2 3.05% mol%, NaOH 81.72 mol%"; the weighed Fe(NO3)3 and Sr(NO3)2 are added to deionized water to prepare the desired solution. A salt solution was prepared by adding weighed NaOH to deionized water. The alkaline solution was added dropwise to the salt solution, and the resulting solid-liquid mixture was transferred to a reactor. The temperature was raised to 220°C at an initial pressure of 1.5 MPa and a heating rate of 1°C / min, and then held for 2 hours. After cooling to room temperature in the furnace, the mixed slurry was removed, filtered, washed, and dried to obtain the auxiliary material.

[0034] The composite gyromagnetic ferrite substrate material prepared in Example 1 has the following properties: saturation magnetization 4πM. s 3718 Gs; Ferromagnetic resonance linewidth ΔH@9.3 GHz 108 Oe; Remanence ratio Br / Bs 0.90; Curie temperature Tc 323.5℃.

[0035] Example 2

[0036] The difference between this embodiment and embodiment 1 is that the auxiliary material added in step 2 is equivalent to 1 wt.% of the mass of the pre-calcined main material.

[0037] The composite gyromagnetic ferrite substrate material prepared in Example 2 has the following properties: saturation magnetization of 4πM. s3733 Gs; Ferromagnetic resonance linewidth ΔH@9.3 GHz 95 Oe; Remanence ratio Br / Bs 0.88; Curie temperature Tc 321.6℃.

[0038] Example 3

[0039] The difference between this embodiment and Embodiment 1 is that the sintering temperature in step 3 is 910℃.

[0040] The composite gyromagnetic ferrite substrate material prepared in Example 3 has the following properties: saturation magnetization of 4πM. s 3666 Gs; Ferromagnetic resonance linewidth ΔH@9.3 GHz 116 Oe; Remanence ratio Br / Bs 0.89; Curie temperature Tc 327.6℃.

[0041] Example 4

[0042] The difference between this embodiment and Embodiment 1 is that the sintering temperature in step 3 is 930℃.

[0043] The composite gyromagnetic ferrite substrate material prepared in Example 4 has the following properties: saturation magnetization of 4πM. s 3779 Gs; Ferromagnetic resonance linewidth ΔH@9.3 GHz 107 Oe; Remanence ratio Br / Bs 0.89; Curie temperature Tc 326.5℃.

[0044] Example 5

[0045] The difference between this embodiment and embodiment 3 is that the auxiliary material added in step 2 is equivalent to 1 wt.% of the mass of the pre-fired main material.

[0046] The composite gyromagnetic ferrite substrate material prepared in Example 5 has the following properties: saturation magnetization of 4πM. s 3628 Gs; Ferromagnetic resonance linewidth ΔH@9.3 GHz 107 Oe; Remanence ratio Br / Bs 0.89; Curie temperature Tc 325.4℃.

[0047] Example 6

[0048] The difference between this embodiment and embodiment 4 is that the auxiliary material added in step 2 is equivalent to 1 wt.% of the mass of the pre-fired main material.

[0049] The composite gyromagnetic ferrite substrate material prepared in Example 6 has the following properties: saturation magnetization 4πM. s 3726 Gs; Ferromagnetic resonance linewidth ΔH@9.3 GHz 108 Oe; Remanence ratio Br / Bs 0.88; Curie temperature Tc 322.7℃.

[0050] Comparative Example

[0051] Compared with Example 1, the difference in the comparative example is that the auxiliary material added in step 2 is equivalent to 0 wt.% of the mass of the pre-calcined main material, that is, no auxiliary material is added.

[0052] The composite gyromagnetic ferrite substrate material prepared in the comparative example has the following properties: saturation magnetization 4πM. s 3912 Gs; Ferromagnetic resonance linewidth ΔH@9.3 GHz 103 Oe; Remanence ratio Br / Bs 0.80; Curie temperature Tc 319.2℃.

[0053] Figure 1 SEM images of the composite ferrite samples prepared for comparison. Figure 2 This is a SEM image of the composite ferrite sample prepared in Example 1. Figure 1 and Figure 2 It is evident that introducing micro / nano structures into SrM powder is beneficial for obtaining a dense microstructure dominated by fine grains. Table 1 shows the gyromagnetic properties of the comparative examples and embodiments. Ti is selected as the main material in this invention. 4+ Mn 3+ Bi 3+ The co-substitution of LiZn ferrite with multiple ions reduces magnetocrystalline anisotropy while ensuring low-temperature sintering, which is beneficial for obtaining a narrow ferromagnetic resonance linewidth. The auxiliary material selected is SrM ferrite with a high Curie temperature. By controlling the ratio of the two phases, a composite gyromagnetic material with both low ferromagnetic resonance linewidth and high Curie temperature can be obtained. Furthermore, the introduction of micro / nano particle technology promotes low-temperature co-sintering of the composite ferrite material, while obtaining a multi-layered dense microstructure dominated by fine grains. This effectively improves the remanence of the composite gyromagnetic ferrite substrate material while maintaining high saturation magnetization.

[0054] Table 1 Performance parameters of comparative examples and embodiments

[0055]

Claims

1. A composite ferrite substrate material for LTCF phase shifters, characterized in that, The material comprises a main component, LiZn ferrite, and an auxiliary component, strontium ferrite. The main component, LiZn ferrite, has the following composition: Li₂CO₃ 11.65~12.33 mol%, ZnO 17.61~22.18 mol%, TiO₂ 8.22~13.31 mol%, Mn₃O₄ 1.85~1.96 mol%, Fe₂O₃ 50.93~59.79 mol%, Bi₂O₃ 0.08~0.09 mol%. The auxiliary component, strontium ferrite, has the following composition: Fe(NO₃)₃ 15.11~15.36 mol%, Sr(NO₃)₂ 2.19~3.78% mol%, NaOH 81.11~82.44 mol%. The content of the auxiliary component, strontium ferrite, is 1~5 wt.% relative to the main component, LiZn ferrite.

2. The composite ferrite substrate material for LTCF phase shifters according to claim 1, characterized in that, The strontium ferrite excipient is a regular hexagonal sheet with a radial diameter of 1~2μm and a thickness of 30~50nm.

3. A method for preparing the composite gyromagnetic ferrite substrate material for LTCF phase shifters as described in claim 1, characterized in that, Includes the following steps: Step 1, Pre-fired material preparation: 1.1 Using LiCO3, ZnO, TiO2, Mn3O4, Fe2O3, and Bi2O3 as raw materials, the raw materials were weighed according to the following proportions: Li2CO3 11.65~12.33 mol%, ZnO 17.61~22.18 mol%, TiO2 8.22~13.31 mol%, Mn3O4 1.85~1.96 mol%, Fe2O3 50.93~59.79 mol%, Bi2O3 0.08~0.09 mol%. The raw materials were ball-milled once for 3~5 hours to obtain a primary slurry. 1.2 After drying and sieving the primary slurry obtained in step 1.1, pre-calcine it in an oxygen furnace at 800-850 ℃ for 1.5-2.5 h. After cooling to room temperature in the furnace, remove it to obtain the pre-calcined main material. Step 2, Secondary ball milling: After sieving the main pre-calcined material obtained in step 1, add 1-5 wt.% of auxiliary material and 2-4 wt.% of Bi2O3 equivalent to the mass of the auxiliary material. The resulting mixture is ball-milled for 5-8 hours. After drying the resulting secondary slurry, composite ferrite abrasive can be obtained. Step 3: Shaping and sintering: 3.1 After sieving the composite ferrite abrasive obtained in step 2, polyvinyl alcohol binder was added to granulate the abrasive, and then a hydraulic press was used to press it into a green sample. 3.2 Place the green sample obtained in step 3.1 into a sintering furnace, heat it to 910-930 ℃, hold it at that temperature for 2 hours, and allow it to cool naturally to room temperature after sintering to obtain the composite gyromagnetic ferrite substrate material.

4. The method for preparing the composite gyromagnetic ferrite substrate material for LTCF phase shifters according to claim 3, characterized in that, The preparation process of the excipients in step 2 is as follows: Fe(NO3)3 is weighed according to the following ratio: Fe(NO3)3 15.11~15.36 mol%, Sr(NO3)2 2.19~3.78% mol%, NaOH 81.11~82.44 mol%. 3、 Sr(NO3) 2、 NaOH raw material; add weighed Fe(NO3)3 and Sr(NO3)2 to deionized water to prepare the solution. A 3.25~3.5 mol / L salt solution; prepare by adding weighed NaOH to deionized water. A 5.359~5.367 mol / L alkaline solution was prepared. The salt solution was added dropwise to the alkaline solution, and the resulting solid-liquid mixture was transferred to a reaction vessel. The mixture was heated to 220°C under 1.5 MPa pressure and held at that temperature for 2 hours. After cooling to room temperature in the furnace, the mixed slurry was removed, filtered, washed, and dried to obtain the auxiliary material.

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