Growth method of large-line-width garnet ferrite single crystal material applied to S-band broadband filter

Abstract

The invention discloses a growth method of a large-line-width garnet ferrite single crystal material applied to an S-band broadband filter, and belongs to the technical field of ferrite single crystal materials. According to the method, Ho < 3 + > ions and Ga < 3 + > ions are used for co-doping, and a PbO-PbF2 fluxing agent system is adopted for growing a garnet Y < 3-x > Ho < x > Fe < 5-y > Ga < y > O < 12 > single crystal, the ferromagnetic resonance line width of the Y (3-x) HoxFe (5-y) GayO12 ferrite single crystal material prepared by the method can reach 20 Oe to 30 Oe, the magnetocrystalline anisotropy field is about 50 Oe, the element doping concentration distribution uniformity is good, the saturation magnetization is 1000 + / -25Gs, and the Y (3-x) HoxFe (5-y) GayO12 ferrite single crystal material can be applied to an ultra-wide instantaneous band wide band-stop filter.

Description

Technical Field

[0001] The invention relates to the technical field of ferrite single crystal materials, and in particular to a method for growing a large-linewidth garnet ferrite single crystal material applied to an S-band broadband filter. Background Art

[0002] Garnet YIG ferrite single crystal material is a ferrimagnetic material with the characteristics of excellent saturation magnetization uniformity, narrow ferromagnetic resonance linewidth, and low dielectric loss. It is an excellent gyromagnetic material and is widely used in various low-frequency, high-Q, and low-insertion-loss microwave devices.

[0003] However, the low ferromagnetic resonance linewidth of YIG ferrite single crystal materials also makes the instantaneous bandwidth of microwave devices narrow. At present, the demand for ultra-wide instantaneous bandwidth ferrite microwave devices in complex electromagnetic environments is increasing. A feasible way to achieve ultra-wide instantaneous bandwidth is to use the ultra-wide resonance peak generated by the merging of ferromagnetic resonance and magnetostatic mode resonance of ferrite single crystal materials. However, due to the large frequency difference between ferromagnetic resonance and magnetostatic mode resonance, the smoothing of the merged peak requires the single crystal material to have a large ferromagnetic resonance linewidth. For example, a band-stop filter with a bandwidth greater than 500 MHz requires a ferrite single crystal ball with a ferromagnetic resonance linewidth greater than 20 Oe. The ferromagnetic resonance linewidth of traditional garnet-type YIG ferrite single crystal materials is generally low, generally about 1 Oe, which obviously cannot meet the needs of ultra-wide instantaneous bandwidth filters. Although the ferromagnetic resonance linewidth of polycrystalline YIG materials can reach tens of Oe, polycrystalline materials lack magnetocrystalline anisotropy and cannot slightly adjust the orientation of the spherical resonators to slightly offset the ferromagnetic resonance frequencies of each spherical resonator, making it difficult to further broaden the instantaneous bandwidth of the multi-stage filter. In addition, polycrystalline materials do not have a temperature-stable axis and have poor temperature characteristics, resulting in a large temperature drift in the ferromagnetic resonance frequency of the small spheres, making it difficult to apply in practice.

[0004] It should be noted that the larger the ferromagnetic resonance line width of ferrite materials, the better. Too large a line width will lead to excessive device insertion loss, which will in turn cause signal distortion. Therefore, the line width of the ferrite material selected for device design should be close to the lower limit of the ferromagnetic resonance line width while meeting the bandwidth requirements. In addition, the operating frequency band of ferrite devices is determined by the saturation magnetization intensity of the material. At present, there is no ferrite material that meets the needs of S-band broadband filters. Summary of the invention

[0005] The purpose of the present invention is to provide a method for growing a large linewidth garnet ferrite single crystal material for use in an S-band broadband filter, so as to solve the above-mentioned problem.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for growing a large linewidth garnet ferrite single crystal material for an S-band broadband filter, the preparation method comprising the following steps: (1) According to the crystal molecular formula Y 3-x Ho x Fe 5-y Ga y O 12 , where 0.07≤ x ≤0.12,0.2≤ y ≤0.3, calculate the mass ratio of the raw materials, which include Y2O3, Ho2O3, Ga2O3, Fe2O3 as solutes and PbO and PbF2 as fluxes, and then accurately weigh each raw material and mix them evenly; (2) placing the raw materials obtained in step (1) into a platinum crucible and compacting it, and then covering the crucible with a platinum crucible lid to seal it; (3) placing the sealed platinum crucible described in step (2) upright in a molten salt furnace for slow cooling growth; (4) After the growth is completed, the crystal in the platinum crucible of step (3) is taken out and the flux is removed to obtain a garnet ferrite single crystal.

[0007] Aiming at the demand for large line width ferrite single crystal materials for S-band ultra-wide instantaneous bandwidth ferrite devices, the present invention improves the raw material formula and uses Ho 3+ Ions and Ga 3+ Ion co-doping, that is, the appropriate amount of Ho 3+ Ions and Ga 3+ The ions partially replaced Y and Fe respectively, regulating the central value of their saturation magnetization intensity at 1000Gs and significantly increasing their ferromagnetic resonance linewidth to above 20 Oe~30 Oe.

[0008] Specifically, the present invention proposes a method for growing a large-linewidth garnet ferrite single crystal material with a saturation magnetization of 1000 Gs±25 Gs and a ferromagnetic resonance linewidth of 20Oe~30 Oe.

[0009] In general, the ferromagnetic resonance linewidth of single crystal materials is determined by the intrinsic properties of the material, fast relaxation ions, and surface finish. Among them, the intrinsic linewidth of YIG single crystal materials is very small, generally less than 1 Oe, and the surface finish is determined by the processing process. Therefore, fast relaxation ion doping is usually used to regulate the ferromagnetic resonance linewidth of single crystal materials. Fast relaxation ions have non-zero orbital angular momentum, which can quickly transfer the energy of consistent precession to the lattice through SL coupling and orbital-crystal field coupling. Therefore, fast relaxation ion doping can significantly increase the ferromagnetic resonance linewidth of single crystal materials. Generally speaking, in YIG single crystal materials, Tb 3+ 、Dy 3+ 、Ho3+ Isofast ions can easily replace Y 3+ ions, and Ho 3+ The ion has large orbital angular momentum and a stable valence state that is not easily changed, so it is a suitable fast relaxation ion for doping. 3+ The doping of ions will also cause the change of the saturation magnetization intensity of the material. Therefore, in order to adjust the saturation magnetization intensity of the single crystal material, Ga 3+ Therefore, the present invention uses Ho 3+ , Ga 3+ Ion co-doping is used to obtain a large-linewidth garnet ferrite single crystal material with controllable saturation magnetization intensity maintained near 1000 Gs.

[0010] As a preferred technical solution, in step (1), the purity of the raw material is ≥99.99wt% As a preferred technical solution, in step (1), the molar ratio of the flux PbO and PbF2 is between 1:1.2 and 1.4.

[0011] As a preferred technical solution, in step (1), the mixing method is ball milling, and the ball milling time is 10 to 12 hours.

[0012] As a preferred technical solution, in step (3), the slow cooling growth process is: heating to 1250°C~1350°C at a heating rate of 100°C / h~150°C / h, keeping the temperature for 10 h~12 h, then rapidly cooling to 1200°C at a cooling rate of 5°C / h~10°C / h, and then slowly cooling to 1050°C at a cooling rate of 0.5°C / h~1.5°C / h.

[0013] As a preferred technical solution, in step (4), the method for removing the flux is to put it into a mixed acid solution of nitric acid / glacial acetic acid dissolved in deionized water and boil it until the flux is completely removed. Preferably, the volume ratio of deionized water: nitric acid: glacial acetic acid is 5:3:2.

[0014] The invention improves the flux formula and the growth process to prepare a garnet-type Y 3-x Ho x Fe 5-y Ga y O 12 Ferrite single crystal materials are of great significance to the development of wide instantaneous bandwidth magnetically tunable filters.

[0015] Compared with the prior art, the advantages of the present invention are: the appropriate proportion of flux used in the present invention effectively reduces the Y 3-x Ho x Fe 5-y Ga y O12 The melting point of the crystal is reduced by 20% and the slow cooling growth process is used to avoid the inclusions and other impurity defects in the crystal. 3+ Ion, Ga 3+ Ion co-doping effectively regulates its saturation magnetization to 1000±25Gs, as well as the fast relaxation Ho 3+ The doping of ions effectively increases the ferromagnetic resonance line width. Compared with YIG and Ga:YIG single crystal materials, the Y 3-x Ho x Fe 5-y Ga y O 12 The ferromagnetic resonance line width of the single crystal is higher, and it can be used for S-band wide instantaneous bandwidth magnetic tuning filter; compared with the polycrystalline YIG material, the single crystal material obtained by the present invention has a higher YIG line width. 3-x Ho x Fe 5-y Ga y O 12 Single crystals have certain magnetocrystalline anisotropy, and the bandwidth of multi-stage filters can be further increased by fine-tuning the orientation of single crystal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Y prepared in Example 1 2.88 Ho 0.12 Fe 4.80 Ga 0.20 O 12 Appearance photo of ferrite single crystal; Figure 2 Y prepared in Example 1 2.88 Ho 0.12 Fe 4.80 Ga 0.20 O 12 Photo of ferrite spherical resonator; Figure 3 Y prepared in Example 1 2.88 Ho 0.12 Fe 4.80 Ga 0.20 O 12 XRD pattern of ferrite single crystal; Figure 4 Y prepared in Example 1 2.88 Ho 0.12 Fe 4.80 Ga 0.20 O 12 Room temperature hysteresis loops of ferrite single crystal along different directions; Figure 5 Y prepared in Example 1 2.88 Ho 0.12 Fe 4.80 Ga0.20 O 12 Ferromagnetic resonance linewidth of ferrite single crystal at 5 GHz. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] Embodiment 1:

[0019] A large line width garnet Y 2.88 Ho 0.12 Fe 4.80 Ga 0.20 O 12 Growth method of ferrite single crystal material: According to the formula, the required Y2O3 (weight 203g), Ho2O3 (weight 22g), Ga2O3 (weight 17g), Fe2O3 (weight 361g), PbO (weight 554g), and PbF2 (weight 824g) were weighed and ball-milled for 4 hours using a ball mill to mix them evenly. Then, the ball-milled raw materials were placed in a platinum crucible, and the pestle was used to compact them, and then the platinum crucible cover was used to seal the crucible; the process curve was set to increase the temperature to 1350℃ at a heating rate of 100℃ / h, keep the temperature for 12h, and then quickly cool down to 1250℃ at a cooling rate of 10℃ / h, and then slowly cool down to 1050℃ at a cooling rate of 1.0℃ / h; then cool down to room temperature with the furnace. After the growth is completed, the crystals are acid-boiled with a mixture of nitric acid (300ml), glacial acetic acid (200ml), and water (500ml) to remove the residual flux.

[0020] Embodiment 2:

[0021] A large line width garnet Y 2.93 Ho 0.07 Fe 4.7 Ga 0.3 O 12 Growth method of ferrite single crystal material: Compared with Example 1, this example only contains “Y2O3 (weight 210 g), Ho2O3 (weight 10 g), Ga2O3 (weight 18.7 g), Fe2O3 (weight 359 g)”, and the rest is the same as Example 1. The chemical composition of the obtained single crystal is Y 2.93 Ho 0.07 Fe 4.70 Ga 0.30 O 12 .

[0022] Comparative Example 1 Compared with Example 1, this comparative example has only "Y2O3 (weight 218g), Ho2O3 (weight 0g), Ga2O3 (weight 21g), Fe2O3 (weight 358g)", and the rest is the same as Example 1. The chemical composition of the obtained single crystal is Y3Fe 4.56 Ga 0.44 O 12 .

[0023] Comparative Example 2 Compared with Example 1, this comparative example only contains “Y2O3 (weight 172g), Ho2O3 (weight 79g), Ga2O3 (weight 0g), Fe2O3 (weight 385g)”, and the rest is the same as Example 1. The chemical composition of the obtained single crystal is Y 2.54 Ho 0.46 Fe5O 12 .

[0024] The morphology of the obtained bulk single crystal of Example 1 is shown in the figure Figure 1 As shown in the figure, the crystal size can reach centimeters, with a maximum linear dimension of 2.0 cm. In order to characterize the physical and chemical properties of the obtained single crystal, XRD and ICP-Ms were used to test and analyze the crystal structure and components. The XRD results are shown in Figure 3 As shown, it shows that the obtained single crystal has good structural integrity and low defects, and its chemical composition is Y 2.88 Ho 0.12 Fe 4.80 Ga 0.20 O 12 , which is in line with the expected design; the obtained single crystals are batch processed and polished into spherical resonators, such as Figure 2 As shown; according to GB / T9633-2012 "Measurement Method for Performance of Gyromagnetic Materials for Microwave Frequency Applications", the saturation magnetization intensity 4πMs of the test sample ball is 1000Gs±25Gs (such as Figure 4 ), and there are differences in the hysteresis loops along different directions, indicating that there is a certain magnetocrystalline anisotropy; the ferromagnetic resonance line width ΔH at 5 GHz is 29.8 Oe (as shown Figure 5 Its ferromagnetic resonance linewidth is significantly higher than that of Ga:YIG single crystal with the same saturation magnetization intensity.

[0025] The saturation magnetization intensity and ferromagnetic resonance line width of the single crystal materials grown in Examples 1 and 2 and Comparative Examples 1 and 2 were tested. Three single crystal balls were tested for each material. The results are shown in Table 1: Table 1 Test results of saturation magnetization intensity and ferromagnetic resonance line width of single crystal materials grown in various embodiments and comparative examples

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for growing a large linewidth garnet ferrite single crystal material for use in an S-band broadband filter, characterized in that: The preparation method comprises the following steps: (1) According to the crystal molecular formula Y 3-x Ho x Fe 5-y Ga y O 12 , where 0.07≤ x ≤0.12,0.2≤ y ≤0.3, calculate the mass ratio of the raw materials, which include Y2O3, Ho2O3, Ga2O3, Fe2O3 as solutes and PbO and PbF2 as fluxes, and then accurately weigh each raw material and mix them evenly; (2) placing the raw materials obtained in step (1) into a platinum crucible and compacting it, and then covering the crucible with a platinum crucible lid to seal it; (3) placing the sealed platinum crucible described in step (2) upright in a molten salt furnace for slow cooling growth; (4) After the growth is completed, the crystal in the platinum crucible of step (3) is taken out and the flux is removed to obtain a garnet ferrite single crystal.

2. The method according to claim 1, characterized in that: In step (1), the purity of the raw material is ≥99.99wt%.

3. The method according to claim 1, characterized in that In step (1), the molar ratio of the flux PbO to PbF2 is between 1:1.2 and 1.

4.

4. The method according to claim 1, characterized in that In step (1), the mixing method is ball milling, and the ball milling time is 10 to 12 hours.

5. The method according to claim 1, characterized in that In step (3), the slow cooling growth process is: heating up to 1250°C~1350°C at a heating rate of 100°C / h~150°C / h, keeping the temperature for 10 h~12 h, then rapidly cooling to 1200°C at a cooling rate of 5°C / h~10°C / h, and then slowly cooling to 1050°C at a cooling rate of 0.5°C / h~1.5°C / h.

6. The method according to claim 1, characterized in that In step (4), the method for removing the flux is to place it in a mixed acid solution of nitric acid / glacial acetic acid dissolved in deionized water and boil it until the flux is completely removed.

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