YIG material for substrate surface sputtering and preparation method thereof

Abstract

The invention discloses a YIG material for substrate surface sputtering and a preparation method thereof, and relates to the technical field of electronic information materials. The surface composite layer is composed of a main body crystal phase Y3Fe4.8Ta0. 2O12, HfO2 quantum dots distributed along a crystal boundary and a Br (at) ZrO2 core-shell structure, the interface transition area contains gadolinium ions, the particle size of the HfO2 quantum dots is set to be 3-5 nm, and the surface density of the HfO2 quantum dots is set to be 2 * 10 < 12 >-4 * 10 < 12 > / cm < 2 >. According to the method, the HfO2 quantum dots with the particle size of 3-5 nm are introduced to the grain boundary, grain boundary diffusion is limited through the quantum size effect, meanwhile, carboxyl functional groups on the surfaces of the HfO2 quantum dots are bonded with main body crystal phases, and therefore the local pinning effect can be formed, and the sputtering yield fluctuation of the yttrium element is compressed from + / -5.2% to + / -0.8%.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic information materials, and particularly to a YIG material for sputtering on the surface of a substrate and a preparation method thereof. Background Art

[0002] Yttrium iron garnet (YIG, YFeO) is an important garnet-type ferrite material. Due to its excellent gyromagnetic effect, low ferromagnetic resonance linewidth, high resistivity, and low dielectric loss and other characteristics, it has a wide range of applications in microwave devices (such as circulators, isolators, filters) and optical devices (such as Faraday rotators, optical isolators). Especially in the field of microwave communication, the YIG substrate material is the core to realize high-performance magneto-optical devices, and its performance directly determines the key indicators such as the bandwidth, insertion loss, and isolation degree of the devices.

[0003] The Chinese invention patent with the publication number CN119592913A discloses a narrow hysteresis width thin film material, its preparation method and application. By doping vanadium dioxide thin film with magnetic rare earth element gadolinium (Gd) and titanium (Ti), as impurity ions, they can effectively replace or destroy the V 4+ -V 4+ covalent bond, thereby increasing the defects in the thin film to regulate the phase change characteristics of the vanadium dioxide thin film. The provided thin film material also has a narrow hysteresis width, which helps to achieve a breakthrough in the wide application of zero hysteresis width. At the same time, it also has excellent reversible phase change and cycle stability, as well as ultra-sensitive temperature response and fast switching characteristics, which can provide strong support for the development of the sensor field.

[0004] In the process of preparing the above-mentioned and existing YIG materials, due to the imbalance in the stripping rate between high sputtering yield elements and low yield elements, a dynamic depletion region of yttrium element is formed on the surface of the target, so that the film composition deviates exponentially from the design value with the sputtering time. At the same time, the low melting point dopant will undergo a thermally induced volatilization-migration coupling effect at high plasma temperature, resulting in a sharp reduction of 40% in the doping efficiency from the center to the edge of the substrate, and a Bi concentration gradient of 60% / 100nm in the thickness direction. Furthermore, it will trigger the synergistic deterioration of vacancies-stress, leading to the insertion loss-bandwidth performance of microwave devices deviating from the design tolerance. Summary of the Invention

[0005] The purpose of the present invention is to provide a YIG material for sputtering on the surface of a substrate and a preparation method thereof, so as to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A YIG material for sputtering on the surface of a substrate, including a main crystal phase Y3Fe 4.8 Ta 0.2 O 12, a surface composite layer composed of HfO2 quantum dots distributed along grain boundaries, a Br@ZrO2 core-shell structure, and an interfacial transition region containing gadolinium ions.

[0007] Furthermore, the particle size of the HfO2 quantum dots is set to 3 - 5 nm, and the areal density of the HfO2 quantum dots is set to 2*10 12 -4*10 12 / cm 2 .

[0008] Furthermore, the concentration of bismuth atoms in the surface composite layer shows a gradient distribution of 18 at% - 8 at% from the core to the surface of the shell.

[0009] Furthermore, in the interfacial transition region, the concentration increment of the gadolinium ions is 80% of the loss amount of yttrium element.

[0010] A preparation method of YIG material uses a YIG material for sputtering on the substrate surface described in any one of the above, and the preparation method includes the following steps:

[0011] S1: Prepare the main crystal phase. Grind the raw materials Y2O3, Fe2O3, and Ta2O5 with zirconia balls for 9 - 14 hours, and at the same time, pre-burn them in a high-temperature atmosphere furnace at a temperature of 25 - 950 °C to obtain pre-burned powder.

[0012] S2: Generate HfO2 quantum dots. Immerse the pre-burned powder in an HfCl4-based solution containing citric acid and polyethylene glycol for a period of time, and then perform vacuum infiltration and centrifugal removal under a cyclic pressure pulse of -0.1 Mpa - atmospheric pressure. At the same time, perform heat treatment in the temperature range of 400 - 700 °C to form HfO2 quantum dots at the grain boundaries of the pre-burned powder to obtain a matrix material.

[0013] S3: Combine the surface core-shell. Set a temperature gradient of 135 - 165 °C in a hydrothermal reaction kettle, and put the raw materials composed of bismuth nitrate and glucose into the hydrothermal reaction kettle to obtain bismuth nanoparticles. At the same time, put the bismuth nanoparticles into an ALD device, and deposit a ZrO2 shell layer on the surface of the bismuth nanoparticles in a gradient manner through a Zr(NEtMe)4 precursor to generate a core-shell structure. At the same time, through rapid hot pressing, combine the core-shell structure and the matrix material to obtain a metallurgical structure.

[0014] S4: Gadolinium ion gradient regulation. Put the metallurgical structure into a MEVVA ion implanter, and at an energy of 45 - 85 keV, inject 2.5*10 15 -6.5*10 15 ions / cm 2Gadolinium ions of a certain concentration are prepared. Meanwhile, the metallurgical structure injected with gadolinium ions is placed in a temperature gradient furnace for gradient annealing treatment in the temperature range of 1100 - 800 °C to generate a four - level gradient structure;

[0015] S5: Final sintering and forming. The four - level gradient structure is placed in a pressure - assisted cold isostatic press for cold isostatic pressing treatment under a pressure of 0 - 250 MPa and a pressure - holding time of 30 - 40 minutes. Meanwhile, the four - level gradient structure after cold isostatic pressing is placed in a three - temperature - zone atmosphere sintering furnace for staged sintering in the temperature range of 25 - 1400 °C to obtain a YIG material with a four - layer gradient composite structure.

[0016] Furthermore, during the grinding process of the zirconia balls, the ball - to - material ratio is set to 5:1. Meanwhile, an ethanol - glycerol solvent is provided inside the zirconia balls, and the volume ratio of the ethanol - glycerol solvent is 7:3 and the solid content is 35 wt%.

[0017] Furthermore, before placing the bismuth nanoparticles into the ALD device, the bismuth nanoparticles are immersed in a 0.1 M ascorbic acid solution, centrifugally washed, and then vacuum - dried at a temperature of 60 °C.

[0018] Furthermore, when the bismuth nanoparticles are placed in the ALD device, a ZrO2 shell layer is formed. The ZrO2 shell layer includes an inner layer, a transition layer, and an outer layer. The thickness of the inner layer is 0.5 nm - 1.0 nm, the thickness of the transition layer is 1.0 nm - 1.8 nm, and the thickness of the outer layer is 1.8 nm - 2.0 nm.

[0019] Furthermore, the temperature gradient furnace is provided with 5 heating zones. Meanwhile, the temperature of the first heating zone is set to 1100 °C, the temperature of the last heating zone is set to 800 °C, and the temperature gradient change between adjacent heating zones is set to 60 °C / cm.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] Firstly: By introducing HfO2 quantum dots with a particle size of 3 - 5 nm at the grain boundaries in the present invention, the grain boundary diffusion is restricted by using the quantum size effect. Meanwhile, the carboxyl functional groups on the surface of the HfO2 quantum dots are phase - bonded to the matrix crystal phase, thereby forming a local pinning effect, and compressing the fluctuation of the yttrium element sputtering yield from ±5.2% to ±0.8%;

[0022] Secondly: By gradient - depositing a ZrO2 shell layer to wrap the bismuth nanoparticles in the present invention, the diffusion coefficient of the bismuth element is reduced from 1×10 -14 m 2 / s to 2×10 -17 m 2 / s, such that the bismuth element concentration shows a gradient distribution of 18 at% to 8 at% from the core to the shell surface, effectively compensating for the plasma flux gradient;

[0023] Thirdly: In the present invention, gadolinium ions are implanted in the interface transition region, and the concentration increment thereof is 80% of the yttrium element loss amount. Through MEVVA ion implantation and gradient annealing operations, a negative correlation gradient is formed between the gadolinium concentration and the yttrium loss;

[0024] Fourthly: In the present invention, through staged cold isostatic pressing and three-temperature zone gradient sintering, and grinding with an ethanol-glycerol solvent, uniform dispersion of ultrafine powder is achieved. Description of the Drawings

[0025] Figure 1 It is the microstructure diagram of the YIG material with a four-layer gradient composite structure of the present invention;

[0026] Figure 2 It is the comparison diagram of the particle size distribution before and after grinding of the present invention;

[0027] Figure 3 It is the microstructure diagram of the YIG material with a four-layer gradient composite structure in Embodiment 1 of the present invention;

[0028] Figure 4 It is the microstructure diagram of the YIG material with a four-layer gradient composite structure in Embodiment 2 of the present invention. Detailed Embodiment

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] During the preparation of existing YIG materials, due to the imbalance in the sputtering rate between high-sputtering-yield elements and low-sputtering-yield elements, a dynamic depletion region of yttrium elements is formed on the surface of the target, causing the film composition to exponentially deviate from the designed value with the sputtering time. At the same time, low-melting-point dopants will undergo a thermally induced volatilization-migration coupling effect at high plasma temperatures, resulting in a sharp reduction of 40% in the doping efficiency from the center to the edge of the substrate, and a Bi concentration gradient of 60% / 100nm in the thickness direction. This will trigger vacancy-stress synergistic degradation, leading to the microwave device insertion loss-bandwidth performance deviating from the design tolerance. The technical solution of this application provides a YIG material with a four-layer gradient composite structure. Through the quantum size effect of the Y2O3 quantum well in this YIG material, the fluctuation of the yttrium element sputtering yield is compressed from ±5.2% to ±0.8%. At the same time, there is a negative correlation between the concentration of gadolinium ions and the concentration of yttrium elements, which can further reduce the depletion rate of yttrium elements. Further, the ZrO2 shell layer provided in this YIG material reduces the diffusion coefficient of bismuth elements from 1×10 -14 m 2 / s to 2×10 -17 m 2 / s, and the bismuth element concentration decreases from 15at% to 8at% from the inside to the outside, compensating for the plasma flux gradient and reducing the bismuth element doping efficiency at the edge of the substrate by only 8%.

[0031] Reference Figure 1 , this embodiment provides a YIG material for sputtering on the surface of a substrate. This YIG material has a four-layer gradient composite structure and includes a main crystal phase Y3Fe 4.8 Ta 0.2 O 12 , surface composite layer composed of HfO2 quantum dots distributed along the grain boundaries, Br@ZrO2 core-shell structure, and an interface transition region containing gadolinium ions. The particle size of the HfO2 quantum dots is set to 3 - 5nm, and the areal density of the HfO2 quantum dots is set to 2*10 12 -4*10 12 / cm 2 . At the same time, the surface of the HfO2 quantum dots is bonded to the main crystal phase Y3Fe 4.8 Ta 0.2 O 12 through carboxyl functional groups. Further, in the surface composite layer, the bismuth atom concentration shows a gradient distribution of 18at% - 8at% from the core to the surface of the shell. In the interface transition region, the concentration increment of gadolinium ions is 80% of the loss amount of yttrium elements.

[0032] Example 1

[0033] This embodiment provides a preparation method of a YIG material. This YIG material has a four-layer gradient composite structure. The specific preparation method includes the following steps:

[0034] Step 1: Prepare the main crystal phase. Fill the initial Y2O3 powder into a crucible, and evacuate the inside of the crucible to a vacuum of 10 -3 Pa to prepare the Y2O3 raw material. At the same time, place the tantalum metal powder in a tubular oxidation furnace, and fill the tubular oxidation furnace with an O2-Ar mixed gas with a ratio of 1:4 to prepare the Ta2O5 raw material.

[0035] Furthermore, from the composition Y3Fe 4.8 Ta 0.2 O 12 of the main crystal phase, it can be known that the molar ratio of yttrium element, iron element and tantalum element is 3:4.8:0.2. Therefore, the molar ratio of the raw materials Y2O3, Fe2O3 and Ta2O5 is 15:24:1, and the mass ratio of the raw materials Y2O3, Fe2O3 and Ta2O5 is 1113:1260:146.

[0036] That is to say, according to the mass ratio of the raw materials Y2O3, Fe2O3 and Ta2O5, put each raw material into zirconia balls, where the ball-to-material ratio is 5:1, and use an ethanol-glycerol solvent with a volume ratio of 7:3 and a solid content of 35 wt% for grinding. Specifically, within the first 4 minutes, rough grind the raw materials at a speed of 600 rpm so that the particle size of the raw materials is 5.0 μm and the specific surface area is 2.8 m 2 / g. Within the next 7 minutes, finely grind the raw materials at a speed of 350 rpm so that the particle size of the raw materials is 0.51 μm and the specific surface area is 12.5 m 2 / g.

[0037] Reference Figure 2 shows that: the particle size after rough grinding is concentrated in the range of 5.0 ± 0.3 μm, and the particle size after fine grinding is concentrated in the range of 0.5 ± 0.05 μm. That is to say, the particles after rough grinding are broken large particles, while the particles after fine grinding are ultrafine and uniform powders.

[0038] Furthermore, put the ground raw materials into a high-temperature atmosphere furnace, inject an Ar-5% H2O mixed gas into the high-temperature atmosphere furnace, and at the same time, within the temperature range of 25 - 680 °C in the high-temperature atmosphere furnace, raise the temperature at a heating rate of 8 °C per minute to remove the volatile components in the raw materials. Within the temperature range of 680 - 950 °C in the high-temperature atmosphere furnace, raise the temperature at a heating rate of 5 °C per minute to inhibit abnormal grain growth and obtain the pre-sintered powder.

[0039] Step 2: Generate HfO2 quantum dots. Mix the HfCl4-based solution and oxalic acid in a molar ratio of 1:2, adjust the pH of the mixed solution to 4.0, add 0.5 wt% PVP solution to the adjusted solution, and stir it with a magnetic stirrer at a rate of 300 rpm for 6 hours. Then, in an ultrasonic cleaner, perform ultrasonic treatment at 40 kHz for 30 minutes to remove the bubbles in the solution and obtain a sol solution.

[0040] Furthermore, immerse the pre-calcined powder obtained in Step 1 in the sol solution for 2 hours, perform vacuum infiltration under a cyclic pulse of 0.5 Hz pressure, and then centrifuge at a rate of 3000 rpm for 5 minutes to remove the unadsorbed sol in the pre-calcined powder.

[0041] Furthermore, place the pre-calcined powder after being treated with the sol solution into a tube furnace, heat it in the tube furnace at a temperature of 450 °C for 1 hour, and fill the tube furnace with N2 and 5% H2 to form HfO2 crystal nuclei with a size of 2 - 3 nm. Then, heat the temperature in the tube furnace to 650 °C and heat the HfO2 crystal nuclei at 650 °C for 2 hours. During the heating process, fill the tube furnace with pure N2 to control the size of the HfO2 crystal nuclei within the range of 3 - 5 nm. That is to say, HfO2 quantum dots are formed at the grain boundaries of the pre-calcined powder, and the matrix material is obtained.

[0042] Step 3: Combine the surface core-shell. Set the temperature of the bottom heating module of the double-layer hydrothermal reaction kettle to 160 °C and the temperature of the top circulating water cooling to 140 °C, so that the vertical temperature difference is 20 °C. At the same time, put the raw materials composed of bismuth nitrate and glucose into the hydrothermal reaction kettle in a molar ratio of 1:2, react for 12 hours, and adjust the pH value of the solution to 8.5 with ammonia water to obtain bismuth nanoparticles with a diameter of 58 nm.

[0043] Furthermore, immerse the obtained bismuth nanoparticles in a 0.1 M ascorbic acid solution with a pH value of 3.0, stir for 30 minutes under nitrogen, then centrifuge and wash at a speed of 6000 rpm for 5 minutes, and vacuum dry at a temperature of 60 °C for 2 hours to obtain the final bismuth nanoparticles.

[0044] Furthermore, the obtained bismuth nanoparticles are placed into an ALD device, and a ZrO₂ shell layer is deposited on the surface of the bismuth nanoparticles in a gradient manner through a Zr(NEtMe)₄ precursor to form a core-shell structure. Specifically, the inner layer thickness of the ZrO₂ shell layer ranges from 0.5 nm to 1.0 m, the transition layer thickness ranges from 1.0 m to 1.8 m, and the outer layer thickness ranges from 1.8 m to 2.0 m. During the formation of the inner layer thickness, the pulse time of the precursor is 0.08 s, the pulse time of the oxidant is 0.03 s, and meanwhile, the bismuth element concentration linearly decreases from 18 at% to 15 at%, and the operation cycle is 1 - 60. During the formation of the transition layer thickness, the pulse time of the precursor is 0.08 s, the pulse time of the oxidant is 0.03 s, and meanwhile, the bismuth element concentration exponentially decreases from 15 at% to 10 at%, and the operation cycle is 61 - 120. During the formation of the outer layer thickness, the pulse time of the precursor is 0.08 s, the pulse time of the oxidant is 0.03 s, and meanwhile, the bismuth element concentration stepwise decreases from 10 at% to 8 at%, and the operation cycle is 121 - 180.

[0045] Furthermore, the core-shell structure is placed into a rapid thermal press furnace and rapidly hot-pressed for 5 minutes under a pressure of 55 MPa, a frequency of 2 Hz, and a temperature of 800 °C to bond the core-shell structure and the matrix material to obtain a metallurgical structure. Meanwhile, during the rapid thermal pressing process, a mixed gas of Ar-H₂-CH₄ with a ratio of 1000:50:1 is filled to form a carbon film to inhibit the oxidation of bismuth elements.

[0046] Step 4: Gadolinium ion gradient regulation. The metallurgical structure obtained in Step 3 is placed into a MEVVA ion implanter. Meanwhile, in the MEVVA ion implanter, gadolinium ions with an energy of 50 keV and a concentration of 3×10 15 ions / cm 2 are implanted into the surface layer of the metallurgical structure with a thickness of 20 - 50 nm. Furthermore, gadolinium ions with an energy of 80 keV and a concentration of 6.5×10 15 ions / cm 2 are implanted into the transition layer of the metallurgical structure with a thickness of 50 - 100 nm.

[0047] It should be noted that when implanting gadolinium ions into the surface layer, the beam current density is set to 5 μA / cm 2 , and the implantation angle is 7° to avoid channeling effects. Meanwhile, when implanting gadolinium ions into the transition layer, the beam current density is set to 8 μA / cm 2 , and the non-implanted area on the metallurgical structure is protected by a polysilicon mask.

[0048] Furthermore, the metallurgical structure injected with gadolinium ions is placed in a temperature gradient furnace, which is provided with 5 independent heating zones. The temperature of the first heating zone is set at 1100 °C, and the temperature of the last heating zone is set at 800 °C. Meanwhile, the temperature gradient change between adjacent heating zones is 60 °C / cm, and the temperature gradient furnace rotates at a speed of 10 rpm.

[0049] Specifically, the axial temperature gradients of the 5 independent heating zones are respectively: 1100 °C, 1040 °C, 950 °C, 890 °C, and 800 °C. The metallurgical structure injected with gadolinium ions is placed in the temperature gradient furnace and moved axially at a speed of 1 cm / h for annealing treatment for 6 hours to generate a four-level gradient structure.

[0050] Step Five: Final sintering and forming. The four-level gradient structure generated in Step Four is placed in a cold isostatic press for staged pressure application and pressure relief treatment. Specifically, during the initial pressure application, it is pressurized from 0 MPa to 50 MPa at a rate of 5 MPa per second and held for 10 minutes to eliminate the voids between the powder particles and achieve pre-densification of the powder. During the main pressure application, it is pressurized to 250 MPa through stepped pressure application and held for 20 minutes to eliminate the elastic deformation of the powder and make it highly densified. During the pressure relief process, linear pressure relief is carried out at a rate of 2 MPa per second, and in coordination with the micro-vibration of the mold, the residual stress is released to prevent layer cracking of the powder.

[0051] Specifically, during the main pressure application, it is pressurized in two stages. In the first pressure application stage, it is pressurized from 50 MPa to 150 MPa at a rate of 10 MPa per second. In the second pressure application stage, it is pressurized from 150 MPa to 250 MPa at a rate of 5 MPa per second.

[0052] Furthermore, the four - level gradient structure after cold isostatic pressing is placed in a three - temperature - zone atmosphere sintering furnace for staged sintering to obtain a four - layer gradient composite structure YIG material. Specifically, during the staged sintering process in the three - temperature - zone atmosphere sintering furnace, it includes three stages: degreasing, pre - sintering, and final sintering. Among them, in the degreasing stage, a mixed gas of Ar - H2 with a ratio of 20:1 is introduced into the three - temperature - zone atmosphere sintering furnace, and the temperature is raised to 600 °C at a heating rate of 5 °C per minute and held for 2 hours to remove organic residues such as PEG / CTAB in the four - level gradient structure. In the pre - sintering stage, a mixed gas of O2 - H2O with a ratio of 100:3 is introduced into the three - temperature - zone atmosphere sintering furnace, and the temperature is raised to 1250 °C at a heating rate of 3 °C per minute and held for 4 hours to promote grain boundary migration in the four - level gradient structure and close residual pores. In the final sintering stage, O2 or H2O with a ratio of 20:1 is introduced into the three - temperature - zone atmosphere sintering furnace, and the temperature is raised to 1400 °C while being held for 6 hours to achieve full densification of the four - level gradient structure.

[0053] Furthermore, after the staged sintering of the four - level gradient structure, staged cooling is carried out to obtain a four - layer gradient composite structure YIG material. Specifically, when cooling from 1400 °C to 600 °C, the cooling rate is 5 °C per minute, and when cooling from 600 °C to 300 °C, the cooling rate is 2 °C per minute. Then it can be naturally cooled to room temperature to obtain a four - layer gradient composite structure YIG material.

[0054] Reference Figure 3 , Figure 3 is the micro - structure diagram of the four - layer gradient composite structure YIG material in this embodiment. It can be seen from Figure 3 that the grain texture fluctuation range is ±0.1, and the grain size is 1.2 ± 0.3 μm. At the same time, the depth of the base layer is 0 - 30 μm, where the quantum dot surface density is 3.2×10 12 / cm 2 and the size is 2 - 5 nm. The depth of the interface transition layer is 30 - 40 μm, where the gadolinium ion concentration gradient distribution is 0.5 - 1.2 at%. The depth of the surface composite layer is 40 - 55 μm, where the core diameter is normally distributed with 58 ± 5 nm, and at the same time, the shell thickness distribution is: 0.5 - 1.0 nm (inner layer), 1.0 - 1.8 nm (middle layer), and 1.9 - 2.0 nm (outer layer).

[0055] Example 2

[0056] This embodiment provides a preparation method of a YIG material. The YIG material is a four - layer gradient composite structure, and the preparation method specifically includes the following steps:

[0057] Step 1: Prepare the main crystal phase. According to the mass ratio among the raw materials Y2O3, Fe2O3 and Ta2O5, put each raw material into zirconia balls for grinding. Specifically, within the first 3 minutes, coarsely grind the raw materials at a rotation speed of 650 rpm, so that the particle size of the raw materials is 5.0 μm and the specific surface area is 2.8 m 2 / g. Within the subsequent 8 minutes, finely grind the raw materials at a rotation speed of 400 rpm, so that the particle size of the raw materials is 0.51 μm and the specific surface area is 12.5 m 2 / g.

[0058] Furthermore, put the ground raw materials into a high-temperature atmosphere furnace, inject an Ar-5% H2O mixed gas into the high-temperature atmosphere furnace, and at the same time, within the temperature range of 25 - 600 °C in the high-temperature atmosphere furnace, increase the temperature at a heating rate of 7.5 °C per minute. Within the temperature range of 600 - 950 °C in the high-temperature atmosphere furnace, increase the temperature at a heating rate of 6.5 °C per minute, so as to inhibit abnormal grain growth and obtain a pre-sintered powder.

[0059] Step 2: Generate HfO2 quantum dots. Immerse the pre-sintered powder obtained in Step 1 in the sol solution for 1.5 hours, perform vacuum infiltration under a cyclic pulse of 1 Hz pressure, and then centrifuge at a rate of 3000 rpm for 5 minutes to remove the unadsorbed sol in the pre-sintered powder.

[0060] Furthermore, put the pre-sintered powder treated with the sol solution into a tube furnace, and at the same time heat it at a temperature of 450 °C in the tube furnace for 0.6 hours, and fill the tube furnace with N2 and 5% H2 to form HfO2 crystal nuclei with a size of 2 - 3 nm. Then heat the temperature in the tube furnace to 700 °C and heat for 2 hours, and during the heating process, fill the tube furnace with pure N2 to obtain a matrix material.

[0061] Step 3: Combine the surface core-shell. Set the temperature of the bottom heating module of the double-layer hydrothermal reaction kettle to 155 °C and the temperature of the top circulating water cooling to 135 °C, so that the vertical temperature difference is 20 °C. At the same time, put the raw materials composed of bismuth nitrate and glucose into the hydrothermal reaction kettle according to a molar ratio of 1:2, react for 12 hours, and adjust the pH value of the solution to 8.5 with ammonia water to obtain bismuth nanoparticles with a diameter of 60 nm.

[0062] Furthermore, put the obtained bismuth nanoparticles into an ALD device, and gradient deposit a ZrO2 shell layer on the surface of the bismuth nanoparticles through a Zr(NEtMe)4 precursor to generate a core-shell structure. At the same time, put the core-shell structure into a rapid thermal press furnace, and rapidly hot press for 5 minutes at a pressure of 55 MPa, a frequency of 2 Hz, and a temperature of 800 °C to combine the core-shell structure and the matrix material to obtain a metallurgical structure.

[0063] Step 4: Gadolinium ion gradient regulation. Place the metallurgical structure obtained in Step 3 into a MEVVA ion implanter. Meanwhile, in the MEVVA ion implanter, with an energy of 50 keV and a gadolinium ion concentration of 4*10 15 ions / cm 2 inject gadolinium ions with a thickness of 20 - 50 nm into the surface layer of the metallurgical structure. Further, with an energy of 80 keV and a gadolinium ion concentration of 6.5*10 15 ions / cm 2 inject gadolinium ions with a thickness of 50 - 100 nm into the transition layer of the metallurgical structure.

[0064] Further, place the metallurgical structure injected with gadolinium ions into a temperature gradient furnace, where the temperature gradient furnace is provided with 5 independent heating zones. The temperature of the first heating zone is set to 1100°C, the temperature of the last heating zone is set to 800°C. Meanwhile, the temperature gradient change between adjacent heating zones is 60°C / cm, and the temperature gradient furnace rotates at a speed of 8 rpm.

[0065] Step 5: Final sintering and forming. Place the four - level gradient structure generated in Step 4 into a cold isostatic press and perform staged pressure application and pressure relief treatment. Specifically, during the initial pressure application, at a rate of 5.5 MPa / second, pressurize from 0 MPa to 50 MPa and hold the pressure for 8 minutes. During the main pressure application, pressurize to 250 MPa in a stepped - pressure manner and hold the pressure for 22 minutes. During the pressure relief process, perform linear pressure relief at a rate of 2 MPa / second.

[0066] Further, place the four - level gradient structure after cold isostatic pressing into a three - temperature - zone atmosphere sintering furnace for staged sintering to obtain a four - layer gradient composite YIG material. Specifically, during the staged sintering process of the three - temperature - zone atmosphere sintering furnace, it includes three stages: degreasing, pre - sintering, and final sintering. Among them, during the degreasing stage, introduce a mixed gas of Ar - H2 with a ratio of 20:1 into the three - temperature - zone atmosphere sintering furnace, and increase the temperature to 600°C at a heating rate of 5°C / minute and hold for 2 hours to remove organic residues such as PEG / CTAB in the four - level gradient structure. During the pre - sintering stage, introduce a mixed gas of O2 - H2O with a ratio of 100:3 into the three - temperature - zone atmosphere sintering furnace, and increase the temperature to 1250°C at a heating rate of 3°C / minute and hold for 4 hours to promote grain boundary migration in the four - level gradient structure and close residual pores. During the final sintering stage, introduce O2 or H2O with a ratio of 20:1 into the three - temperature - zone atmosphere sintering furnace, increase the temperature to 1400°C, and hold for 6 hours to achieve full densification of the four - level gradient structure.

[0067] Furthermore, after the staged sintering of the four-level gradient structure, staged cooling is carried out to obtain a four-layer gradient composite structure of YIG material. Specifically, when cooling from 1400 °C to 600 °C, the cooling rate is 5 °C per minute, and when cooling from 600 °C to 300 °C, the cooling rate is 2 °C per minute. Then it can be naturally cooled to room temperature to obtain a four-layer gradient composite structure of YIG material.

[0068] Reference Figure 4 , Figure 4 is the microstructure diagram of the YIG material with a four-layer gradient composite structure in this embodiment. As Figure 4 can be seen, the grain texture fluctuation range is ±0.08, the grain size is 1.0 ± 0.2 μm, and its grain distribution is more uniform compared with Figure 3 . At the same time, the depth of the base layer is 0 - 30 μm, where the surface density of HfO2 quantum dots is 4.5*10 12 / cm 2 . Compared with Figure 3 , it can be seen that the density of HfO2 quantum dots has increased by 20%. The depth of the interface transition layer is 30 - 40 μm, where the concentration gradient distribution of gadolinium ions is 0.6 - 1.4 at%. Compared with Figure 3 , it can be seen that the concentration gradient of gadolinium ions has expanded by 17%. The depth of the surface composite layer is 40 - 55 μm, where the core diameter is normally distributed with 60 ± 4 nm, and at the same time, the distribution of the shell thickness is: 0.6 - 1.2 nm (inner layer), 1.2 - 1.9 nm (middle layer), and 1.9 - 2.2 nm (outer layer). Compared with Figure 3 , it can be seen that the core-shell thickness has increased by 10%.

[0069] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A YIG material for sputtering on the surface of a substrate, characterized in that, Including a main crystal phase Y3Fe 4.8 Ta 0.2 O 12 , a surface composite layer composed of HfO2 quantum dots distributed along grain boundaries, a Br@ZrO2 core-shell structure, and an interfacial transition region containing gadolinium ions.

2. The YIG material for sputtering on the substrate surface according to claim 1, wherein The particle size of the HfO2 quantum dots is set to 3 - 5 nm, and the areal density of the HfO2 quantum dots is set to 2*10 12 - 4*10 12 / cm 2 .

3. A YIG material for sputtering on the surface of a substrate according to claim 1, characterized in that, The concentration of bismuth atoms in the surface composite layer shows a gradient distribution of 18 at% - 8 at% from the core to the surface of the shell layer.

4. A YIG material for sputtering on the surface of a substrate according to claim 1, characterized in that, In the interface transition region, the concentration increment of the gadolinium ions is 80% of the loss amount of the yttrium element.

5. A preparation method of YIG material, characterized in that, A YIG material for sputtering on the substrate surface described in any one of claims 1 - 4 is used, and the preparation method includes the following steps: S1: Prepare the main crystal phase. Grind the raw materials Y2O3, Fe2O3, and Ta2O5 with zirconia balls for 9 - 14 hours, and at the same time, pre - sinter in a high - temperature atmosphere furnace at a temperature of 25 - 950 °C to obtain the pre - sintered powder. S2: Generate HfO2 quantum dots. Immerse the pre - sintered powder in an HfCl4 - based solution containing citric acid and polyethylene glycol for a period of time, then perform vacuum infiltration and centrifugal removal under a cyclic pressure pulse of - 0.1 Mpa - atmospheric pressure, and at the same time, perform heat treatment in the temperature range of 400 - 700 °C to form HfO2 quantum dots at the grain boundaries of the pre - sintered powder to obtain the matrix material. S3: Combine the surface core - shell structure. Set a temperature gradient of 135 - 165 °C in a hydrothermal reaction kettle, put the raw materials composed of bismuth nitrate and glucose into the hydrothermal reaction kettle to obtain bismuth nanoparticles, and at the same time, put the bismuth nanoparticles into an ALD device, and deposit a ZrO2 shell layer on the surface of the bismuth nanoparticles in a gradient manner through a Zr(NEtMe)4 precursor to generate a core - shell structure. At the same time, combine the core - shell structure and the matrix material through rapid hot pressing to obtain a metallurgical structure. S4: Gadolinium ion gradient regulation. Place the metallurgical structure into a MEVVA ion implanter, and at an energy of 45 - 85 keV, inject gadolinium ions with a concentration of 2.5*10 15 - 6.5*10 15 ions / cm 2 into the interface transition region of the metallurgical structure. At the same time, place the metallurgical structure injected with gadolinium ions into a temperature gradient furnace and perform gradient annealing treatment in the temperature range of 1100 - 800 °C to generate a four - level gradient structure; S5: Final sintering and forming. Put the four - level gradient structure into a pressure - assisted cold isostatic press, perform cold isostatic pressing treatment under a pressure of 0 - 250 MPa and a pressure - holding time of 30 - 40 minutes. At the same time, put the four - level gradient structure after cold isostatic pressing treatment into a three - temperature - zone atmosphere sintering furnace for staged sintering in the temperature range of 25 - 1400 °C to obtain the YIG material with a four - layer gradient composite structure.

6. The preparation method of a YIG material according to claim 5, characterized in that, During the grinding process of the zirconia balls, the ball - to - material ratio is set to 5:

1. At the same time, an ethanol - glycerol solvent is arranged inside the zirconia balls, and the volume ratio of the ethanol - glycerol solvent is 7:3 and the solid content is 35 wt%.

7. The preparation method of a YIG material according to claim 5, characterized in that, Before putting the bismuth nanoparticles into the ALD device, immerse the bismuth nanoparticles in a 0.1 M ascorbic acid solution, perform centrifugal cleaning, and then perform vacuum drying at a temperature of 60 °C.

8. A method for preparing a YIG material according to claim 5 or 7, characterized in that, Put the bismuth nanoparticles into the ALD device, and the generated ZrO2 shell layer includes an inner layer, a transition layer, and an outer layer. The thickness of the inner layer is 0.5 nm - 1.0 nm, the thickness of the transition layer is 1.0 nm - 1.8 nm, and the thickness of the outer layer is 1.8 nm - 2.0 nm.

9. The preparation method of a YIG material according to claim 5, characterized in that, There are 5 heating zones set in the temperature gradient furnace. At the same time, the temperature of the first heating zone is set to 1100 °C, the temperature of the last heating zone is set to 800 °C, and the temperature gradient change between adjacent heating zones is set to 60 °C / cm.

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