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CN-122010186-A - Preparation method of ion-doped yttrium iron garnet powder

CN122010186ACN 122010186 ACN122010186 ACN 122010186ACN-122010186-A

Abstract

The invention relates to a preparation method of ion-doped yttrium iron garnet powder, belonging to the field of material preparation. A preparation method of ion doped yttrium iron garnet powder comprises the following steps of firstly synthesizing polymer network gel containing Ce, bi, Y, fe ions, calcining the obtained polymer network gel to obtain loose porous oxide precursor powder, and placing the obtained oxide precursor powder in a high-temperature horizontal throwing ball mill for high-temperature controlled pressure atmosphere ball milling to finally obtain the ion doped yttrium iron garnet powder, wherein the chemical composition of the ion doped yttrium iron garnet powder is Ce a Bi b Y (3‑a‑b) Fe 5 O 12 , a is less than or equal to 0.4, b is less than or equal to 0.4, and a and b are different from 0. The method can obtain the composite oxide powder with high phase purity, low defect density and good density and grain uniformity.

Inventors

  • ZHAO QING
  • HUANG XINGXI
  • ZHANG JING
  • WANG SHANGFEI
  • XING XIAOYAN
  • LIU CHENGJUN

Assignees

  • 东北大学

Dates

Publication Date
20260512
Application Date
20260415

Claims (10)

  1. 1. The preparation method of the ion doped yttrium iron garnet powder is characterized in that the chemical composition of the ion doped yttrium iron garnet powder is Ce a Bi b Y (3-a-b) Fe 5 O 12 , wherein a is less than or equal to 0.4, b is less than or equal to 0.4, and a and b are not 0 at the same time, and the method comprises the following process steps: S1, preparing mixed metal nitrate solution containing Y, fe ions and Ce and Bi ions required by the target chemical composition according to the chemical composition Ce a Bi b Y (3-a-b) Fe 5 O 12 of the target ion doped yttrium iron garnet powder, adding complexing agent citric acid monohydrate, regulating pH value, adding hydrophilic polymerizable monomer acrylamide, cross-linking agent N, N-methylene bisacrylamide and initiator ammonium persulfate, polymerizing to obtain polymeric network wet gel, and drying to obtain polymeric network xerogel; S2, treating the polymeric network xerogel obtained in the step S1 at 300-500 ℃ for a period of time to obtain loose porous oxide precursor powder; S3, placing the oxide precursor powder obtained in the step S2 into a ball milling tank of a high-temperature horizontal drop-off ball mill, filling three grinding balls with the diameters of 5mm, 8mm and 12 mm, wherein the mass fractions of the three grinding balls are respectively 20% -30%, 50% -55% and 20% -30%, the sum of the mass fractions of the three grinding balls is 100%, the ball material ratio is 40:1, ball milling is started after filling, ball milling comprises three stages of heating, heat preservation and cooling, ball milling is kept at the same ball milling rotation speed, wherein the ball milling rotation speed is 65% -85% of the critical rotation speed of the ball mill, the heat preservation temperature is 500-700 ℃, the total gauge pressure of the ball mill is 0.11-0.20 MPa, the ball mill atmosphere is in the heating and heat preservation stages, argon with the oxygen content of less than or equal to 0.005% is introduced, argon with the oxygen content of 0.05% is introduced in the cooling stage, and argon with the oxygen content of less than or equal to 0.005% is introduced in the rest stage of cooling.
  2. 2. The method of claim 1, wherein the step S1 is characterized in that a mixed metal nitrate solution containing Y, fe ions and Ce and Bi ions required by the target chemical composition is prepared according to the chemical composition Ce a Bi b Y (3-a-b) Fe 5 O 12 of the target ion doped yttrium iron garnet powder, complexing agent citric acid monohydrate is added into the mixed metal nitrate solution, stirring is carried out until the complexing agent citric acid monohydrate is dissolved, ammonia water with the mass fraction of 25% is added to adjust the pH of the solution to 5.0+/-0.1, a metal-citric acid complexing precursor solution is obtained, a monomer-cross-linking agent system is obtained after hydrophilic polymerizable monomer acrylamide and cross-linking agent N, N-methylene bisacrylamide are dissolved in water, the monomer-cross-linking agent system is added into the metal-citric acid complexing precursor solution, the mixed solution is obtained after uniform mixing, the water bath temperature is kept at 40 ℃, initiator ammonium persulfate is added into the mixed solution according to 0.5% -1.5% of the mass of the hydrophilic polymerizable monomer, stirring is carried out in a 70 ℃ water bath for 3 h, a polymerization network wet gel is formed, and the polymerization network wet gel is dried for 70-90-32 hours, and a dry polymerization network is obtained.
  3. 3. The method according to claim 2, wherein the concentration of Fe ions in the mixed metal nitrate solution is 0.5 to 1 mol/L.
  4. 4. The method according to claim 2, wherein the concentration of the hydrophilic polymerizable monomer acrylamide in water is 4.0-7.5 mol/L, and the concentration of the cross-linking agent N, N-methylenebisacrylamide in water is 0.4-1.2 mol/L.
  5. 5. The method according to claim 2, wherein the ratio of the hydrophilic polymerizable monomer acrylamide to the total metal cations in the mixed metal nitrate solution is 5-25:1, and the ratio of the complexing agent citric acid monohydrate to the total metal cations in the mixed metal nitrate solution is 1.25-2:1.
  6. 6. The method according to claim 1, wherein the step S2 is to treat the polymeric network xerogel obtained in the step S1 in a muffle furnace at 300-500 ℃ for 2-8 hours to obtain loose porous oxide precursor powder.
  7. 7. The method according to claim 1, wherein step S2 is performed under an air or oxygen-containing atmosphere.
  8. 8. The method according to claim 1, wherein in the step S3, the effective inner diameter of the ball milling tank is 0.15 m, the ball milling rotation speed is 71-93 r/min, and the heat preservation ball milling time is 4-8 h.
  9. 9. The method according to claim 1, wherein in the step S3, the temperature rising rate is 2.5-4 ℃ per minute, and the temperature lowering rate is 80-100 ℃ per hour.
  10. 10. The method according to claim 1, wherein in the step S3, the ball mill tank is a 304 austenitic stainless steel ball mill tank, and the grinding balls are 304 austenitic stainless steel grinding balls.

Description

Preparation method of ion-doped yttrium iron garnet powder Technical Field The invention relates to a preparation method of ion-doped yttrium iron garnet powder, belonging to the field of material preparation. Background Yttrium iron garnet has a complex cubic structure with a chemical formula of Y 3Fe5O12 (YIG), each unit cell contains eight molecular units, and the crystal structure contains three interstitial sites, Y 3+ with a larger radius, occupying the 24c site (oxydodecahedron interstitial), and Fe 3+ occupying the 16a site (oxyoctahedral interstitial) and the 24d site (oxytetrahedral interstitial). The multi-lattice structure provides rich possibilities for ion doping, for example, bi, ce, dy, la, gd plasma can replace Y ion at c position for improving saturation magnetization, magneto-optical Faraday effect, curie temperature and resistivity, and Ni, ga plasma can replace Fe ion at a position or d position for adjusting magnetic dilution and light absorption. The key properties of YIG and its Ce, bi, gd, ga dopant are determined by both crystal chemistry and defect chemistry. The valence state of Fe determines the magneto-optical properties of the base, while the valence state and occupation of Ce and Bi directly determine the effect of doping modification and the phase purity and density. By locking the trivalent state of the valence-changing element, a phase stability area can be effectively defined, and the defect concentration can be regulated, so that the performance index of the cured material can be improved. For the preparation of YIG powder, the prior art has undergone a series of evolutions. In order to shorten the flow and reduce the cost, chemical preparation processes are becoming a research hotspot. For example, in chinese patent CN117602674a published in 2024, liu Guixiang et al describe a method for obtaining nano YIG powder by sintering by sol-gel method and fuel combustion method using nitrate, citric acid and glycine as raw materials. Although the prior art realizes flow shortening and cost control to a certain extent, with the continuous improvement of the performance requirements of the magneto-optical ceramics in the industry, the prior preparation technology still faces thermodynamic and kinetic barriers which are difficult to overcome when facing to multi-component complex ion doping. In order to reduce the synthesis temperature, jiang Linwen discloses a method for preparing YIG powder by combining self-propagating combustion by taking citric acid as a complexing agent and combining the self-propagating combustion in the 'self-propagating combustion method for preparing YIG powder and the performance study' of the YIG powder in the 'Shuoshi' paper (2006). Although this approach attempts to improve uniformity through the wet precursor route, it still relies substantially on the chemical complexation equilibrium of metal ions with citric acid. In Bi, ce, fe, Y and other multicomponent systems, the complexing constants of the ions are greatly different, and micro segregation is very easy to occur in the gel drying process. Chinese patent CN102942226a also shows that the xerogel after self-propagating combustion still needs to be calcined at high temperature of 800-1000 ℃ to obtain single-phase YIG with good crystallization. Meanwhile, studies in H.A. Harwig et al, thermochimica Acta, 1979, 28 (1): 121-131, indicate that bismuth oxide has a melting point of only about 825 ℃ and undergoes a sharp phase transition above 730 ℃. This means that the above path cannot fundamentally solve the contradiction between volatilization of the low-melting point dopant and the high temperature required for phase formation, and it is difficult to prepare a powder with high Bi content and accurate stoichiometric ratio. Chinese patent CN109133167a discloses a method for preparing copper zirconate powder by high temperature mechanochemical method, wherein the reaction is promoted by introducing argon gas for protection and heating during ball milling. While this prior art discloses a "high temperature + ball milling" process version, it is directed to zirconate systems and employs only a single inert atmosphere control. For Ce, bi and YIG systems, there is an extremely complex "valence-volatilization" contradiction that Ce 3+ is very easily oxidized to Ce 4+ at high temperatures, while Bi 3+ is very volatile at low or high temperatures. Simple argon protection technology cannot accurately prevent Ce from being oxidized, and lacks a mechanism for inhibiting Bi volatilization. Chinese patent CN106517865B discloses that conventional solid phase processes typically require long sintering times at high temperatures above 1100 ℃, far exceeding the melting point limit of Bi, leading to severe volatilization. The chemical coprecipitation method is limited by the large difference in precipitation behavior between Fe 3+ and Y 3+, zhang W et al MATERIALS CHEMISTRY AND PHYSICS, 2011, 125 (3): 646-651. The pub