Growth method of high-uniformity Ga-doped YIG single crystal material

Abstract

The invention discloses a growth method of a high-uniformity Ga-doped YIG single crystal material, and belongs to the technical field of ferrite single crystal materials.According to the method, a garnet Y3Fe (5-x) GaxO12 single crystal is grown through a high-temperature and high-pressure optical floating zone method, compared with a traditional fluxing agent method, the method can effectively avoid the influence of the element segregation phenomenon on doping uniformity, and the doping uniformity of the garnet Y3Fe (5-x) GaxO12 single crystal is improved. The prepared Y3Fe5-xGaxO12 single crystal material has good doping uniformity, high saturation magnetization consistency and almost no gradient distribution, and can be applied to YIG oscillators and magneto-optical isolators with high requirements on the quality of the single crystal material.

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 high-uniformity Ga-doped YIG single crystal material. Background Art

[0002] Garnet YIG ferrite single crystal material is a ferrimagnetic material with excellent uniformity of saturation magnetization, narrow ferromagnetic resonance line width, and low dielectric loss. It is an excellent gyromagnetic material and is widely used in various low-frequency, high-Q value, and low insertion loss microwave devices. In order to meet the needs of different frequency bands and application scenarios, it is usually necessary to modify the garnet YIG ferrite single crystal material by ion doping to adjust the electromagnetic performance parameters such as saturation magnetization and ferromagnetic resonance line width.

[0003] However, the flux method is currently widely used to grow garnet-type YIG ferrite single crystal materials, and the doping elements generally have element segregation in the flux, which will lead to the concentration of the doping elements in the grown crystal being inconsistent with the concentration of the doping elements in the raw material formula, and also cause the concentration of the doping elements in the crystal to gradually change with the growth of the crystal, thereby causing the distribution of the doping elements in the crystal to be uneven, resulting in poor uniformity of the crystal's saturation magnetization, ferromagnetic resonance linewidth, Faraday rotation angle and other index parameters. Taking the Ga-doped YIG single crystal material grown by the flux method as an example, its saturation magnetization distribution deviation can generally reach 100 Gs to 200 Gs. For example, for a crystal with a saturation magnetization center value of 1000 Gs, its actual distribution may be between 900 Gs and 1100 Gs. The serious non-uniformity of the distribution of doping elements may lead to problems such as deterioration of the phase noise of the oscillator and wavefront distortion of the magneto-optical isolator in actual device applications, making it difficult to meet the use needs of devices such as oscillators and magneto-optical isolators that have extremely high requirements on the quality of single crystal materials. Summary of the invention

[0004] In response to the demand for high-uniformity ferrite single crystal materials for oscillators, magneto-optical isolators, etc., the present invention grows Ga-YIG single crystal materials with high doping uniformity based on the high-temperature and high-pressure floating zone method, greatly improves the uniformity of the saturation magnetization intensity distribution of the Ga-YIG single crystal material, and proposes a growth method for high-uniformity Ga-doped YIG single crystal materials.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for growing a highly uniform Ga-doped YIG single crystal material, comprising the following steps: (1) According to the crystal molecular formula Y 3 Fe 5-x Ga x O 12, the raw material Fe 2 O 3 , Y 2 O 3 and Ga 2 O 3 , according to the molar ratio Y 2 O 3 :Fe 2 O 3 :Ga 2 O 3 =3:5- x : x (0≤ x ≤1) weighing and grinding and mixing uniformly to obtain a raw material main body mixed powder, recorded as A powder; (2) The raw material Fe 2 O 3 , Y 2 O 3 and Ga 2 O 3 , according to the molar ratio Y 2 O 3 :Fe 2 O 3 :Ga 2 O 3 =1:0.6~0.8×(5- x ): 0.6~0.8× x (0≤ x ≤1) weighing and grinding and mixing uniformly to obtain flux mixed powder, which is recorded as B powder; (3) placing the powder A and powder B obtained in step (1) and step (2) in containers respectively, sintering them at 1000°C to 1300°C for more than 20 hours respectively, and then naturally cooling them to room temperature before taking them out; (4) grinding and fully crushing the sintered powder A and powder B obtained in step (3); (5) Take a clean straight balloon and fill the B powder that has been crushed in step (4) as a flux into the straight balloon; then continue to fill the A powder that has been crushed in step (4) as the main raw material into the balloon; (6) Tightening the balloon filled with the powder in step (5), and pressing it in an isostatic press to obtain an initial raw material rod; (7) placing the initial material rod obtained in step (6) in a muffle furnace for sintering, and then naturally cooling it to room temperature before taking it out; (8) The material rod sintered in step (7) is vertically suspended in a high-temperature and high-pressure optical floating zone furnace (such as SciDreHKZ-100 bar), and high-purity oxygen is introduced. The parameters of the floating zone furnace are adjusted to maintain a maximum light flux of 45% to 55%. The moving speed of the upper and lower drive rods is 1 mm / h to 3 mm / h. The growth time is 30 to 40 hours to obtain Y 3 Fe 5-x Ga x O 12 Single crystal material.

[0006] The resulting single crystal material was more than 5 centimeters long and about 4 millimeters in diameter.

[0007] In order to improve the uniformity of element doping of YIG single crystal materials and obtain a highly uniform Ga-doped YIG single crystal material to meet the needs of devices such as oscillators and magneto-optical isolators, the present invention grows highly uniform Ga-doped YIG single crystal materials based on the high temperature and high pressure floating zone method, and the crystal size can reach Φ4*50 mm 3 , the ferromagnetic resonance linewidth is less than 1 Oe, and the saturation magnetization intensity deviation is ≤±15Gs.

[0008] As a preferred technical solution, in step (1) and step (2), the raw material is a high-purity raw material with a purity of ≥99.99wt%.

[0009] As a preferred technical solution, in step (4), the particle sizes of the two powders after crushing are both less than 10 μm.

[0010] As a preferred technical solution, in step (5), the filling depth of the B powder is 2 mm to 5 mm, and the filling depth of the A powder is 30 mm to 60 mm.

[0011] As a preferred technical solution, in step (6), the material is pressed into a cylinder with a length of more than 4 cm and a diameter of 5 to 6 mm.

[0012] As a preferred technical solution, in step (7), the sintering temperature is 1300°C to 1400°C, and the sintering time is more than 24 hours.

[0013] As a preferred technical solution: in step (8), the purity of the high-purity oxygen is 99.999%.

[0014] The present invention adopts the floating zone method to prepare garnet-type Y 3 Fe 5-x Ga x O 12 Ferrite single crystal materials are of great significance to the development of devices such as oscillators and magneto-optical isolators.

[0015] Compared with the conventional flux-based Ga-YIG single crystal growth process, the present invention has the following advantages: the floating zone method adopted by the present invention limits the flux to only a small fixed area (i.e., the floating zone). During the crystal growth process, the melting of the raw material and the crystallization and precipitation of the solute are carried out simultaneously, maintaining the stability of the floating zone components, thereby keeping the components of the growing crystal unchanged, avoiding the influence of the element segregation phenomenon in the conventional flux-based growth method, greatly improving the doping uniformity of the Ga element, and further improving the uniformity of the saturation magnetization intensity distribution of the single crystal material. The high-uniformity Ga-YIG single crystal material obtained by the present invention has a higher uniformity of saturation magnetization intensity distribution than the Ga-YIG single crystal material grown by the conventional flux-based method, and can be used in a YIG oscillator to improve phase noise. It can also be used in a magneto-optical isolator to effectively improve the wavefront distortion problem of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Y prepared in Example 1 3 Fe 4.56 Ga 0.44 O 12 Appearance photo of ferrite single crystal; Figure 2 Y prepared in Example 1 3 Fe 4.56 Ga 0.44 O 12 XRD pattern of ferrite single crystal; Figure 3 Y prepared in Example 1 3 Fe 4.56 Ga 0.44 O 12 Ferromagnetic resonance linewidth of ferrite single crystal; Figure 4 Y prepared in Example 1 3 Fe 4.56 Ga 0.44 O 12 EDS elemental analysis photos of ferrite single crystal; Figure 5 Y prepared in Comparative Example 1 3 Fe 4.56 Ga 0.44 O 12 Appearance photo of ferrite single crystal; Figure 6 For comparative example 2, Y 3 Fe 4.56 Ga 0.44 O 12 The ferrite crystal is an unstable floating zone image and the crystal cannot grow. DETAILED DESCRIPTION

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

[0018] Embodiment 1:

[0019] A method for growing a highly uniform Ga-doped YIG single crystal material comprises the following steps: (1) Weigh the raw materials and ball mill them separately: Weigh the Y required for the raw material A separately 2 O 3 (weight 13.55 g), Ga 2 O 3 (weight 1.61 g), Fe 2 O 3 (weight 14.60 g), and use a ball mill for 4 hours to mix it evenly; at the same time, weigh the Y required for flux powder B 2 O 3 (weight 2.26 g), Ga 2 O 3 (weight 0.65 g), Fe 2 O 3 (weight 5.84 g), and ball milled for 4 hours using a ball mill to make it uniformly mixed; (2) Sintering and ball milling: The ball-milled powder A and powder B are placed in clean alumina ceramic crucibles and sintered at 1200 °C for 20 h. After cooling to room temperature, they are taken out and crushed again to a particle size of less than 10 μm. (3) Material filling: First, fill the B powder used as flux into a clean straight balloon to a depth of 4 mm; then continue to fill the main raw material A powder into the balloon to a depth of 50 mm; (4) Isostatic pressing and secondary sintering: After loading, the powder is pressed into a cylinder at a pressure of 100 MPa in an isostatic press to obtain an initial raw material rod, which is then sintered at 1300 °C for 24 hours and then naturally cooled to room temperature before being taken out. (5) Crystal growth: The sintered material rod is then vertically suspended in a high-temperature and high-pressure optical floating zone furnace (SciDreHKZ-100bar) and high-purity oxygen (99.999%) is introduced. The floating zone furnace parameters are adjusted to maintain 50% of the maximum light flux, and the movement rate of the upper and lower drive rods is 1 mm / h. Stable growth is carried out for 40 hours. The morphology of the obtained rod-shaped single crystal is shown in the figure Figure 1 As shown, the crystal has a shiny surface and is cylindrical in shape, about 5 cm long and 4 mm in diameter.

[0020] In order to characterize the physical and chemical properties of the obtained single crystal, XRD and EDS were used to test and analyze the crystal structure and components. The results are as follows: Figure 2 , Figure 4 As shown, it shows that the obtained single crystal has good structural integrity and low defects, and its chemical composition is Y 3 Fe 4.56 Ga 0.44 O 12 , in line with the expected design.

[0021] Embodiment 2:

[0022] A method for growing a highly uniform Ga-doped YIG single crystal material comprises the following steps: Compared with Example 1, this example only weighs Ga 2 O 3 (weight 0 g), Fe 2 O 3 (Weight 15.97g)", "Flux powder B weighs Ga 2 O 3 (weight 0 g), Fe 2 O 3 (weight 4.79 g)", the rest is the same as in Example 1, and the chemical composition of the obtained single crystal is Y 3 Fe 5 O 12 .

[0023] Embodiment 3:

[0024] A method for growing a highly uniform Ga-doped YIG single crystal material comprises the following steps: Compared with Example 1, this example only weighs Ga 2 O 3 (weight 3.75 g), Fe 2 O 3 (Weight 12.78 g)", "Flux powder B weighs Ga 2 O 3 (weight 1.13 g), Fe 2 O 3 (weight 3.83 g)", the rest is the same as in Example 1, the chemical composition of the obtained single crystal is Y 3 Fe 4 GaO 12 .

[0025] According to GB / T9633-2012 "Measurement Method for Performance of Gyromagnetic Materials for Microwave Frequency Applications", the saturation magnetization intensity 4πMs and the ferromagnetic resonance line width ΔH at 5GHz of the sample were tested. The test results are shown in Table 1. The 4πMs distribution is 1000Gs±15Gs, ΔH£0.845 Oe (such as Figure 3 The EDS element distribution analysis is shown as follows Figure 4As shown, it shows that the Ga element is evenly distributed in the crystal cross section.

[0026] The saturation magnetization intensity and ferromagnetic resonance line width of the single crystal materials grown in Examples 1-3 were tested, and the results are shown in Table 1: Table 1 Test results of saturation magnetization and ferromagnetic resonance line width of single crystal materials grown in Example 1, Example 2 and Example 3

[0027] Comparative Example 1: Compared with Example 1, this comparative example is the same as Example 1 except that "in step (5), the moving speed of the upper and lower driving rods is 5 mm / h." The rest is the same as Example 1. The obtained crystal is as follows Figure 5 As shown, the surface is dull and matte.

[0028] Comparative Example 2: Compared with Example 1, this comparative example only includes "in step (1), the flux powder B is weighed Y 2 O 3 (weight 2.26 g), Ga 2 O 3 (weight 1.3 g), Fe 2 O 3 (weight 11.68 g)", the rest is the same as in Example 1, and the results are as follows Figure 6 As shown, no crystalline material can be grown.

[0029] 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 highly uniform Ga-doped YIG single crystal material, characterized in that: The steps include: (1) According to the crystal molecular formula Y3Fe 5-x Ga x O 12 , the raw materials Fe2O3, Y2O3 and Ga2O3 are mixed according to the molar ratio of Y2O3:Fe2O3:Ga2O3=3:5- x : x , where 0≤ x ≤1, weigh and grind and mix evenly to obtain a mixed powder of the main raw materials, recorded as A powder; (2) The raw materials Fe2O3, Y2O3 and Ga2O3 are mixed according to the molar ratio of Y2O3:Fe2O3:Ga2O3=1:0.6~0.8×(5- x ): 0.6~0.8× x , where 0≤ x ≤1, weigh and grind and mix evenly to obtain flux mixed powder, recorded as B powder; (3) placing the powder A and powder B obtained in step (1) and step (2) in containers respectively, sintering them at 1000°C to 1300°C for more than 20 hours respectively, and then naturally cooling them to room temperature before taking them out; (4) grinding and fully crushing the sintered powder A and powder B obtained in step (3); (5) Take a clean straight balloon and fill the powder B that has been crushed in step (4) as a flux into the balloon; then continue to fill the powder A that has been crushed in step (4) as the main raw material into the balloon; (6) Tightening the balloon filled with the powder in step (5), and pressing it in an isostatic press to obtain an initial raw material rod; (7) placing the initial material rod obtained in step (6) in a muffle furnace for sintering, and then naturally cooling it to room temperature before taking it out; (8) The material rod sintered in step (7) is vertically suspended in a high-temperature and high-pressure optical floating zone furnace, and high-purity oxygen is introduced. The floating zone furnace parameters are adjusted to maintain a maximum light flux of 45% to 55%. The moving speed of the upper and lower drive rods is 1 mm / h to 3 mm / h. The growth time is 30 to 40 hours to obtain Y3Fe 5-x Ga x O 12 Single crystal material.

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

3. The method according to claim 1, characterized in that In step (4), the particle sizes of the two powders after crushing are both less than 10 μm.

4. The method according to claim 1, characterized in that In step (5), the filling depth of the B powder is 2 mm to 5 mm, and the filling depth of the A powder is 30 mm to 60 mm.

5. The method according to claim 1, characterized in that In step (6), the product is pressed into a cylinder having a length of more than 4 cm and a diameter of 5 to 6 mm.

6. The method according to claim 1, characterized in that In step (7), the sintering temperature is 1300°C to 1400°C, and the sintering time is more than 24 hours.

7. The method according to claim 1, characterized in that: In step (8), the purity of the high-purity oxygen is 99.999%.

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