Cerium-doped yttrium iron garnet single crystal thick film and preparation method thereof

Abstract

The invention relates to the technical field of magneto-optical materials, and particularly provides a cerium-doped yttrium iron garnet single crystal thick film and a preparation method thereof. The chemical formula of the cerium-doped yttrium iron garnet single crystal thick film is Ce < x > R < 3-x > Fe < y > M < z > A < 5-y-z > O < 12 >, x is equal to 0.3 to 1.4, y is equal to 0.05 to 5, and z is equal to 0.01 to 1; in the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, the element R is europium Eu, and / or the element A is selected from at least one of zirconium Zr, silicon Si and tin Sn. According to the method, the Ce < 4 + > concentration in the growth stage of the single crystal thick film is reduced, so that the product quality of the cerium-doped yttrium iron garnet single crystal thick film is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magneto - optical materials, and more particularly, to a cerium - doped yttrium iron garnet single - crystal thick film and a preparation method thereof. Background Art

[0002] YIG (yttrium iron garnet) is a garnet - type ferrite with good gyromagnetic effect, low resonance linewidth, high resistivity, and low dielectric loss. These properties make YIG have important applications in microwave technology. The crystal structure of YIG is a complex body - centered cubic structure, belonging to the cubic crystal system. There are 8 molecules and a total of 160 atoms in each unit cell.

[0003] Ce 3+ Doping can significantly improve the magneto - optical response of YIG, especially enhancing its Faraday rotation angle in the near - infrared region. This enhancement is due to the interaction between Ce 3+ and Fe 3+ in the YIG lattice, resulting in new optical and electronic transitions in the crystal. However, during the preparation of cerium - doped yttrium iron garnet, there is a transformation from Ce 3+ to Ce 4+ and the formation of CeO2 heterophase. Ce 4+ makes no contribution to the magneto - optical effect and increases the absorption rate, increasing the optical loss of the device. The common method to reduce Ce 4+ at present is to use a reducing atmosphere (such as H2) to increase the proportion of Ce 3+ during the thermal annealing treatment after the thick film is grown. Passing hydrogen during annealing increases energy consumption on the one hand and has limited inhibition on the Ce 4+ concentration on the other hand. Therefore, how to reduce the Ce 4+ concentration during the single - crystal thick - film growth stage has become an urgent problem to be solved. Summary of the Invention

[0004] The present invention aims to reduce the Ce 4+ concentration during the single - crystal thick - film growth stage to improve the product quality of the cerium - doped yttrium iron garnet single - crystal thick film.

[0005] To solve the above problems, the present invention provides a cerium - doped yttrium iron garnet single - crystal thick film and a preparation method thereof. The specific technical solutions are as follows:

[0006] As a first aspect, the present invention provides a cerium - doped yttrium iron garnet single - crystal thick film, and the chemical formula of the cerium - doped yttrium iron garnet single - crystal thick film is Ce x R 3-x Fe y M z A 5-y-z O 12, where x = 0.3 to 1.4, y = 0.05 to 5, and z = 0.01 to 1;

[0007] In the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, the R element is europium (Eu), and / or the A element is selected from at least one of zirconium (Zr), silicon (Si), and tin (Sn).

[0008] Optionally, in the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, if the A element is selected from at least one of zirconium (Zr), silicon (Si), and tin (Sn), the R element is selected from at least one of europium (Eu), yttrium (Y), samarium (Sm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), bismuth (Bi), and lanthanum (La).

[0009] Optionally, in the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, the M element is selected from at least one of indium (In), chromium (Cr), aluminum (Al), gallium (Ga), cobalt (Co), scandium (Sc), and manganese (Mn).

[0010] As a second aspect, the present invention also provides a method for preparing a cerium-doped yttrium iron garnet single crystal thick film for preparing the above-mentioned cerium-doped yttrium iron garnet single crystal thick film, including: preparing the cerium-doped yttrium iron garnet single crystal thick film by liquid phase epitaxy.

[0011] Optionally, the liquid phase epitaxy method includes:

[0012] Weigh CeO2, Fe2O3, the oxide of R, the oxide of M, and the oxide of A according to the molar ratio, and at the same time add a flux, mix evenly to obtain a raw material mixture;

[0013] Heat the raw material mixture to melting and keep it warm to obtain a molten raw material;

[0014] After cooling the molten raw material, immerse the substrate in the molten raw material for single crystal thick film growth to obtain a cerium-doped yttrium iron garnet single crystal thick film.

[0015] Optionally, the weighing of CeO2, Fe2O3, the oxide of R, the oxide of M, and the oxide of A according to the molar ratio includes:

[0016] In terms of molar ratio, Fe2O3 / (CeO2 + the oxide of R) = (10 to 30):1, Fe2O3 / (the oxide of M and the oxide of A) = (4 to 100):1, (CeO2 + Fe2O3 + the oxide of R + the oxide of M + the oxide of A) / (CeO2 + Fe2O3 + the oxide of R + the oxide of M + the oxide of A + the flux) = (0.1 to 0.7):1, CeO2 / the oxide of R = (2 to 8):1, and the oxide of M / the oxide of A = (1 to 5):1.

[0017] Optionally, the flux includes B2O3 and PbO, and the molar ratio of PbO to B2O3 is (1 to 15):1.

[0018] Optionally, the step of heating the raw material mixture until it is melted and then keeping the temperature to obtain a raw material melt comprises: heating the raw material mixture to 1050° C.-1250° C. and keeping the temperature, and rotating the raw material mixture at a rotation speed of 10 to 60 rpm while heating.

[0019] Optionally, after cooling the raw material melt, immersing the substrate into the raw material melt, and growing a single crystal thick film comprises: after cooling the temperature of the raw material melt to a supersaturation temperature, immersing the substrate into the raw material melt and maintaining the temperature for 30 to 90 minutes.

[0020] Optionally, after cooling the raw material melt, immersing the substrate into the raw material melt to grow a single crystal thick film to obtain a cerium-doped yttrium iron garnet single crystal thick film, the method further includes: heat-bathing the cerium-doped yttrium iron garnet single crystal thick film in a nitric acid aqueous solution, with a heat-bathing temperature of 60°C to 130°C and a heat-bathing time of 30min to 120min.

[0021] The beneficial effects of the present invention compared to the prior art are:

[0022] The present invention introduces one or more elements of Zr, Si, Sn and Eu into the cerium-doped yttrium iron garnet single crystal thick film through material reverse design, and optimizes Ce by regulating the doping amount of each element. 4+ The concentration of Eu occupies the R element position, Zr, Si, and Sn occupy the A element position, and Zr 4+ 、Si 4+ Sn 2+ 、Eu 2+ The reducibility of each 4+ Restore to Ce 3+ , thereby keeping Ce stably at +3 valence, and achieving Ce in the liquid phase epitaxial growth stage 3+ Concentration stability. The present invention overcomes the problem of many defects in YIG thick films caused by the presence of CeO2 impurity phase in the growth of traditional cerium-doped YIG thick films, stabilizes the crystal field environment related to the magneto-optical effect, helps the single crystal grow to a higher thickness, improves the Faraday rotation angle, and meets the application requirements of high isolation and low loss of non-reciprocal devices such as optical isolators. Therefore, the present invention can fundamentally reduce the concentration of CeO2 impurity phase, effectively avoid lattice distortion, improve the product quality of cerium-doped yttrium iron garnet single crystal thick film, and does not require subsequent treatment, which simplifies the post-processing process of single crystal thick film, effectively saves production costs, and is conducive to the industrialization and mass production of cerium-doped single crystal thick films. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the flow chart for the preparation of cerium-doped yttrium iron garnet single crystal thick film in the embodiments of the present invention;

[0024] Figure 2 This is the XRD pattern of the cerium-doped yttrium iron garnet single crystal thick film in Embodiments 1 to 3 of the present invention;

[0025] Figure 3 This is the transmission spectrum of the cerium-doped yttrium iron garnet single crystal thick film in Embodiments 1 to 3 of the present invention;

[0026] Figure 4 This is the Faraday loop diagram of the cerium-doped yttrium iron garnet single crystal thick film in Embodiments 1 to 3 of the present invention;

[0027] Figure 5 This is the MH diagram of the cerium-doped yttrium iron garnet single crystal thick film in Embodiments 1 to 3 of the present invention. Detailed implementation manners

[0028] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following provides a detailed description of the specific embodiments of the present invention.

[0029] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific implementation manners and are not intended to limit this application;

[0030] The term "including" and its variations used herein are open-ended, that is, "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc. mentioned in the present invention are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0031] In the preparation process of yttrium iron garnet single crystal thick film, a common method to reduce Ce 4+The methods mainly include the following: (1) Raw material preparation stage: Add B2O3, PbO, etc. as fluxes to the raw materials. By controlling the melt composition and temperature, ensure the uniform distribution of Fe and Ce elements in the melt. At the same time, control the melt temperature between 800 - 850 °C to avoid the formation of Ce 4+ ; (2) Growth stage: After immersing the substrate in the melt, by optimizing the cooling rate and supersaturation, the crystal growth rate can be slowed down, enabling Ce 3+ to enter the YIG lattice more stably and reducing lattice distortion and local oxygen vacancies caused by rapid growth; (3) Post-treatment stage: Anneal in a reducing atmosphere (H2, N2) to inhibit the oxidation of Ce 4+ to Ce 3+ .

[0032] However, the above methods have limited inhibitory effect on the Ce 4+ concentration. In order to further reduce the Ce 4+ concentration in the single-crystal thick film growth stage, the present invention provides a cerium-doped yttrium iron garnet single-crystal thick film and a preparation method thereof.

[0033] As a first aspect, the present invention relates to a cerium-doped yttrium iron garnet single-crystal thick film. The chemical formula of the cerium-doped yttrium iron garnet single-crystal thick film is Ce x R 3-x Fe y M z A 5-y-z O 12 , where x = 0.3 to 1.4, y = 0.05 to 5, z = 0.01 to 1; in the chemical formula of the cerium-doped yttrium iron garnet single-crystal thick film, the R element is europium Eu, and / or the A element is selected from at least one of zirconium Zr, silicon Si, and tin Sn.

[0034] Through material reverse design, the present invention introduces one or more elements of Zr, Si, Sn, Eu into the cerium-doped yttrium iron garnet single-crystal thick film. By regulating the doping amount of each element, the inhibitory effect on the Ce 4+ concentration is optimized. Among them, Eu occupies the position of the R element, and Zr, Si, Sn occupy the position of the A element. Utilize the respective reducibility of Zr 4+ , Si 4+ , Sn 2+ , Eu 2+ to reduce Ce 4+ to Ce 3+ , thereby stably maintaining Ce at +3 valence and realizing the inhibition of Ce 3+Stability of concentration. The present invention overcomes the problem of more defects in YIG thick films caused by the presence of CeO2 heterophase in the growth of traditional cerium-doped YIG thick films, stabilizes the crystal field environment related to the magneto-optical effect, helps the single crystal to grow to a higher thickness, increases the Faraday rotation angle, and meets the application requirements of high isolation and low loss for non-reciprocal devices such as optical isolators. Therefore, the present invention can fundamentally reduce the concentration of CeO2 heterophase, effectively avoid lattice distortion, eliminate the need for subsequent processing, simplify the post-treatment process of single crystal thick films, effectively save production costs, and is conducive to the industrialization and batch production of cerium-doped single crystal thick films.

[0035] In some alternative embodiments, in the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, if the A element is selected from at least one of zirconium Zr, silicon Si, and tin Sn, then the R element is selected from at least one of europium Eu, yttrium Y, samarium Sm, gadolinium Gd, terbium Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, ytterbium Yb, lutetium Lu, bismuth Bi, and lanthanum La.

[0036] It should be understood that in the cerium-doped yttrium iron garnet single crystal thick film of the embodiment of the present invention, at least one element of Eu, Zr, Si, and Sn should be doped. Among them, when Eu is doped, the Eu element occupies the R element position of yttrium iron garnet, and the R element is generally at the c position of the dodecahedron; when Zr, Si, or Sn is doped, Zr, Si, or Sn respectively occupies the A element position of yttrium iron garnet, and at this time, other elements such as Eu and Y can occupy the R element position of yttrium iron garnet.

[0037] Furthermore, in some alternative embodiments, the M element is selected from at least one of indium In, chromium Cr, aluminum Al, gallium Ga, cobalt Co, scandium Sc, and manganese Mn.

[0038] It should be noted that in the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film of the present invention, each of the R and M elements can respectively include one or several elements. For example, in some alternative embodiments, in the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, the R element includes europium Eu and / or yttrium Y, and the M element is selected from one or two of indium In, aluminum Al, scandium Sc, cobalt Co, and manganese Mn.

[0039] In the embodiment of the present invention, by further introducing the above elements into the YIG lattice, the lattice structure, magnetic properties, optical properties, and interface characteristics of YIG can be regulated, and the directional optimization of material properties can be achieved. Specifically, for example, the doping of indium (In 3+ ) can slightly expand the lattice constant, reduce the lattice stress, improve the quality of the single crystal, reduce the lattice mismatch between the thin film and the substrate, inhibit the generation of dislocations, and improve the optical uniformity. For example, the doping of gallium (Ga 3+ ) and aluminum (Al 3+ ) can replace Fe 3+sites, weakening the super-exchange interaction, reducing the Curie temperature and saturation magnetization intensity. During practical applications, the working temperature range of magneto-optical devices can be adjusted, and the high-frequency magnetic loss can be reduced. The doping of scandium (Sc 3+ ) introduces local lattice distortion, enhances magnetocrystalline anisotropy, is beneficial to optimizing the magnetic domain structure, and improving the response speed of magneto-optical devices. The doping of Co, Mn, and Cr is beneficial to enhancing the magneto-optical effect. The co-doping of Ce with the above elements can achieve the synergistic enhancement of the Faraday rotation angle and reduce the Ce 3+ oxidation tendency through lattice relaxation, improving the doping stability.

[0040] In some alternative embodiments, the thickness of the cerium-doped yttrium iron garnet single crystal thick film is 10 to 500 μm.

[0041] The cerium-doped yttrium iron garnet single crystal thick film in the present invention has a large thickness range and can meet the thickness requirements of different scenarios. For example, in magneto-optical devices, a sufficient thickness (100 to 300 microns) is required to enhance the Faraday rotation angle and balance the optical loss, but in microwave devices, a thinner film (10 to 100 microns) is required to reduce signal delay and loss.

[0042] As a second aspect, the present invention also provides a method for preparing a cerium-doped yttrium iron garnet single crystal thick film for preparing the above-mentioned cerium-doped yttrium iron garnet single crystal thick film. Referring to Figure 1 as shown, this preparation method includes: preparing the cerium-doped yttrium iron garnet single crystal thick film by liquid phase epitaxy.

[0043] Specifically, the above liquid phase epitaxy method includes the following steps:

[0044] S1: Raw material mixing: Weigh CeO2, Fe2O3, the oxides of R, the oxides of M, and the oxides of A according to the molar ratio, and at the same time add a flux, mix evenly to obtain a raw material mixture. Specifically, in terms of molar ratio, Fe2O3 / (CeO2 + the oxides of R) = (10 to 30):1, Fe2O3 / (the oxides of M and A) = (4 to 100):1, (CeO2 + Fe2O3 + the oxides of R + the oxides of M + the oxides of A) / (CeO2 + Fe2O3 + the oxides of R + the oxides of M + the oxides of A + the flux) = (0.1 to 0.7):1, CeO2 / the oxides of R = (2 to 8):1, the oxides of M / the oxides of A = (1 to 5):1.

[0045] As an example, in some alternative embodiments, the oxide of R may be Eu2O3 and Y2O3, the oxide of M may be Sc2O3, Al2O3, In2O3, Co2O3 and MnO, the oxide of A may be SnO2, and each substance is weighed and mixed according to the stoichiometric ratio. The flux may include B2O3 and PbO, and the molar ratio of PbO to B2O3 is (1 to 15):1. In addition, to improve the mixing effect, a ball mill may be used to fully mix the above-mentioned weighed raw materials. The ball mill is set at 500 rpm and ball milling is maintained for 24 h.

[0046] S2: Melting of the raw material mixture: The raw material mixture is heated to melting and then kept warm to obtain a molten raw material. Specifically, the raw material mixture may be filled into a crucible for liquid phase epitaxy, and then the crucible is placed inside the liquid phase epitaxy furnace and heated to 1050 °C - 1250 °C and kept warm. While heating, the raw material mixture is rotated at a speed of 10 - 60 rpm until the oxide is fully melted. After the oxide is fully melted, it may be kept warm at 1050 °C - 1250 °C for 2 - 12 hours until there are no particles, film-like substances and unmelted lumpy impurities on the liquid surface.

[0047] S3: Thick film growth: After the molten raw material is cooled, the substrate is immersed in the molten raw material for single crystal thick film growth to obtain a cerium-doped yttrium iron garnet single crystal thick film. Specifically, the temperature of the molten raw material may be reduced by 150 °C - 550 °C to the supersaturation temperature to ensure that no particles, film-like substances and lumpy impurities precipitate at this temperature. Then the cleaned substrate is placed on a substrate fixture and installed on a lifting rod. The lifting rod is controlled to slowly descend to immerse the substrate in the molten raw material and kept for 30 min to 90 min to ensure that the substrate gradually adapts to the growth temperature. During the single crystal thick film growth process, the molten raw material (crucible) and the substrate are rotated respectively. After the growth is completed, the lifting rod is slowly lifted out to obtain a single crystal thick film with impurities adhered. During this process, the concentration of Ce 3+ becomes stable after the single crystal thick film growth is completed, and there is no process of Ce 3+ transforming to Ce 4+ , and subsequent valence reduction treatment with a reducing gas is not required.

[0048] It should be noted that the substrates used for single crystal thick film growth include but are not limited to any one of GGG, SGGG, GSGG, YSGG, NGG, LCLNGG, Al2O3, Si, SiC, GYSGG.

[0049] S4: Thick film cleaning: The cerium-doped yttrium iron garnet single crystal thick film is subjected to a hot bath in an aqueous nitric acid solution, the hot bath temperature is 60 °C to 130 °C, and the hot bath time is 30 min to 120 min.

[0050] The present invention will be described in detail below through specific embodiments:

[0051] Embodiment 1

[0052] The cerium-doped yttrium iron garnet single crystal thick film is prepared according to the following steps:

[0053] S1: Raw material mixing: Weigh CeO2, Eu2O3, Fe2O3, Y2O3, Sc2O3, Al2O3, B2O3 and PbO according to the following molar ratios: Fe2O3 / (CeO2 + Eu2O3 + Y2O3) = 10:1, Fe2O3 / (Sc2O3 + Al2O3) = 8:1, PbO / B2O3 = 2:1, (CeO2 + Eu2O3 + Fe2O3 + Y2O3 + Sc2O3 + Al2O3) / (CeO2 + Eu2O3 + Fe2O3 + Y2O3 + Sc2O3 + Al2O3 + B2O3 + PbO) ＝ 0.25:1, CeO2 / (Eu2O3 + Y2O3) = 2:1. Use a ball mill to fully mix the above-weighed raw materials. The ball mill is set at 500 rpm and the ball milling time is 24 h to obtain a raw material mixture.

[0054] S2: Melting of the raw material mixture: Fill the raw material mixture into a crucible, place the crucible inside the liquid phase epitaxy furnace chamber, set the rotation speed of the crucible to 15 rpm, heat up to 1200 °C. At this time, the oxides are fully melted. After the oxides are fully melted, keep warm for 2 hours until the liquid surface of the melt is as smooth as a mirror to obtain a raw material melt.

[0055] S3: Thick film growth: Place the cleaned SGGG substrate on a platinum fixture and install it on the lifting rod. Cool the raw material melt to the supersaturation temperature of 850 °C. At this time, control the axial movement of the lifting rod to slowly immerse the SGGG substrate into the oxide melt for 1 h to grow the thick film. During the growth process, the rotation speed of the crucible is 10 rpm and the rotation speed of the substrate is 20 rpm. After the growth is completed, slowly lift the lifting rod to obtain a single crystal thick film with impurities attached.

[0056] S4: Thick film cleaning: Mix nitric acid and water at a ratio of 1:1 and heat to 120 °C to obtain a nitric acid aqueous solution. Then heat-bath the single crystal thick film with impurities attached in the nitric acid aqueous solution for 1 h. Through EDS testing, obtain a clean cerium-doped yttrium iron garnet single crystal thick film with the molecular formula of Ce1Eu 0.5 Y 1.5 Fe 4.7 Sc 0.2 Al 0.1 O 12 of.

[0057] In this embodiment, in the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, the R element is yttrium Y and europium Eu, the M element is scandium Sc and aluminum Al, x = 1, y = 4.7, and z = 0.3.

[0058] Example 2

[0059] S1: Raw material mixing: Weigh CeO2, Eu2O3, Fe2O3, Y2O3, In2O3, Al2O3, B2O3, and PbO according to the following molar ratios. Among them, Fe2O3 / (CeO2 + Eu2O3 + Y2O3) = 10:1, Fe2O3 / (In2O3 + Al2O3) = 5.5:1, PbO / B2O3 = 2:1, (CeO2 + Eu2O3 + Fe2O3 + Y2O3 + In2O3 + Al2O3) / (CeO2 + Eu2O3 + Fe2O3 + Y2O3 + In2O3 + Al2O3 + B2O3 + PbO) = 0.4:1, and CeO2 / (Eu2O3 + Y2O3) = 1.8:1. Use a ball mill to fully mix the above-mentioned weighed raw materials. Set the ball mill to 500 rpm and the ball milling time to 24 h to obtain a raw material mixture.

[0060] S2: Melting of the raw material mixture: Fill the raw material mixture into a crucible, place the crucible inside the liquid phase epitaxy furnace chamber, set the rotation speed of the crucible to 15 rpm, heat up to 1250 °C. At this time, the oxides are fully melted. After the oxides are fully melted, keep warm for 4 hours until the liquid surface of the melt is as smooth as a mirror to obtain a raw material melt.

[0061] S3: Thick film growth: Place the cleaned SGGG substrate on a platinum fixture and install it on the lifting rod. Cool the raw material melt to the supersaturation temperature of 800 °C. At this time, control the axial movement of the lifting rod to slowly immerse the SGGG substrate into the oxide melt for 1 h to grow the thick film. During the growth process, the rotation speed of the crucible is 10 rpm and the rotation speed of the substrate is 20 rpm. After the growth is completed, slowly lift the lifting rod to obtain a single crystal thick film with impurities attached.

[0062] S4: Thick film cleaning: Mix nitric acid and water at a ratio of 1:1 and heat to 120 °C to obtain a nitric acid aqueous solution. Then, heat-bath the single crystal thick film with impurities attached in the nitric acid aqueous solution for 1 h. Through EDS testing, obtain a clean cerium-doped yttrium iron garnet single crystal thick film with the molecular formula Ce1Eu1Y1Fe 4.5 In 0.3 Al 0.2 O 12 of.

[0063] In this embodiment, in the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, the R element is yttrium Y and europium Eu, the M element is indium In and aluminum Al, x = 1, y = 4.5, and z = 0.5.

[0064] Example 3

[0065] S1: Raw material mixing: Weigh CeO2, SnO2, MnO, Fe2O3, Co2O3, Y2O3, B2O3, and PbO according to the following stoichiometric ratios: Fe2O3 / (CeO2 + Y2O3) = 12:1, Fe2O3 / (SnO2 + MnO + Co2O3) = 5:1, PbO / B2O3 = 2:1, (CeO2 + SnO2 + MnO + Fe2O3 + Co2O3 + Y2O3) / (CeO2 + SnO2 + MnO + Fe2O3 + Co2O3 + Y2O3 + B2O3 + PbO) = 0.45:1, CeO2 / Y2O3 = 2.5:1, MnO + Co2O3 / SnO2 = 2.1:1. Use a ball mill to fully mix the above-weighed raw materials. Set the ball mill to 500 rpm and the ball milling time to 24 h to obtain a raw material mixture.

[0066] S2: Melting of the raw material mixture: Fill the raw material mixture into a crucible, place the crucible inside the liquid phase epitaxy furnace chamber, set the rotation speed of the crucible to 15 rpm, heat up to 1150 °C. At this time, the oxides are fully melted. After the oxides are fully melted, keep them warm for 6 h until the surface of the melt is as smooth as a mirror to obtain a raw material melt.

[0067] S3: Thick film growth: Place the cleaned SGGG substrate on a platinum fixture and install it on the lifting rod. Cool the raw material melt to the supersaturation temperature of 835 °C. At this time, control the axial movement of the lifting rod to slowly immerse the SGGG substrate into the oxide melt for 1 h to grow the thick film. During the growth process, the rotation speed of the crucible is 10 rpm and the rotation speed of the substrate is 20 rpm. After the growth is completed, slowly lift the lifting rod to obtain a single crystal thick film with impurities attached.

[0068] S4: Thick film cleaning: Mix nitric acid and water at a ratio of 1:1 and heat to 120 °C to obtain a nitric acid aqueous solution. Then, heat-bath the single crystal thick film with impurities attached in the nitric acid aqueous solution for 1 h. Through EDS testing, obtain a clean cerium-doped yttrium iron garnet single crystal thick film with the molecular formula Ce1Y2Fe4Co 0.5 Sn 0.3 Mn 0.2 O 12 Sn.

[0069] In this embodiment, in the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, the R element is yttrium Y, the M element is cobalt Co and manganese Mn, the A element is tin Sn, x = 1, y = 4, and z = 0.7.

[0070] The XRD patterns, transmission spectra, Faraday loop diagrams, and MH diagrams of the cerium-doped yttrium iron garnet single crystal thick films prepared in Examples 1 to 3 of the present invention are successively as Figures 2 to 5 shown.

[0071] Figure 2 from bottom to top in the figure are the blank SGGG substrate and the XRD patterns of the cerium-doped yttrium iron garnet single crystal thick films in Examples 1 to 3. It can be Figure 2 seen that the three single crystal thick films have obvious epitaxial peaks (444) on the SGGG substrate, indicating that the cerium-doped yttrium iron garnet single crystal thick film of the present invention can be successfully crystallized.

[0072] Figure 3 In the figure, the abscissa is the wavelength of light and the ordinate is the transmittance. It can be Figure 3 seen that after the single crystal thick films in the three examples are doped with Eu and Sn respectively, in the near-infrared band (such as a wavelength of 1000 nm), the transmittance can reach more than 90%, and the absorption rate is significantly reduced.

[0073] Figure 4 In the figure, the abscissa is the magnetic field strength and the ordinate is the Faraday rotation angle. It can be Figure 4 seen that after the single crystal thick films in the three examples are doped with Eu and Sn respectively, they have the giant Faraday effect, and the unit Faraday rotation angle is on the order of 10 4 deg / cm, and the Faraday rotation angle of the single crystal thick film in Example 2 with a higher Eu 3+ concentration is larger.

[0074] Figure 5 In the figure, the abscissa is the magnetic field strength and the ordinate is the magnetization intensity of the material. It can be Figure 5 seen that when the externally applied magnetic field strength gradually increases, the magnetization intensities of the single crystal thick films in Examples 1 to 3 increase accordingly and reach the saturation magnetization intensity, and they all have good magnetism.

[0075] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A cerium-doped yttrium iron garnet single crystal thick film, characterized in that, The chemical formula of the cerium-doped yttrium iron garnet single crystal thick film is Ce x R 3-x Fe y M z A 5-y-z O 12 , where x = 0.3 to 1.4, y = 0.05 to 5, z = 0.01 to 1; In the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, the R element is europium (Eu), and / or the A element is selected from at least one of zirconium (Zr), silicon (Si), and tin (Sn).

2. The cerium-doped yttrium iron garnet single crystal thick film according to claim 1, characterized in that In the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, if the A element is selected from at least one of zirconium (Zr), silicon (Si), and tin (Sn), the R element is selected from at least one of europium (Eu), yttrium (Y), samarium (Sm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), bismuth (Bi), and lanthanum (La).

3. The cerium-doped yttrium iron garnet single crystal thick film according to claim 1, wherein In the chemical formula of the cerium-doped yttrium iron garnet single crystal thick film, the M element is selected from at least one of indium (In), chromium (Cr), aluminum (Al), gallium (Ga), cobalt (Co), scandium (Sc), and manganese (Mn).

4. A method for preparing a cerium-doped yttrium iron garnet single crystal thick film, characterized in that, To prepare the cerium-doped yttrium iron garnet single crystal thick film according to any one of claims 1-3, it includes: preparing the cerium-doped yttrium iron garnet single crystal thick film by liquid phase epitaxy.

5. The preparation method of the cerium-doped yttrium iron garnet single crystal thick film according to claim 4, characterized in that, The liquid phase epitaxy method includes: Weighing CeO2, Fe2O3, the oxide of R, the oxide of M, and the oxide of A according to the molar ratio, and at the same time adding a flux, mixing them evenly to obtain a raw material mixture; Heating the raw material mixture to melting and then holding it to obtain a molten raw material; After cooling the molten raw material, dipping a substrate into the molten raw material to grow a single crystal thick film, thereby obtaining a cerium-doped yttrium iron garnet single crystal thick film.

6. The preparation method of the cerium-doped yttrium iron garnet single crystal thick film according to claim 5, characterized in that, The step of weighing CeO2, Fe2O3, the oxide of R, the oxide of M, and the oxide of A according to the molar ratio includes: In terms of molar ratio, Fe2O3 / (CeO2 + the oxide of R) = (10 to 30):1, Fe2O3 / (the oxide of M and the oxide of A) = (4 to 100):1, (CeO2 + Fe2O3 + the oxide of R + the oxide of M + the oxide of A) / (CeO2 + Fe2O3 + the oxide of R + the oxide of M + the oxide of A + the flux) = (0.1 to 0.7):1, CeO2 / the oxide of R = (2 to 8):1, the oxide of M / the oxide of A = (1 to 5):

1.

7. The preparation method of the cerium-doped yttrium iron garnet single crystal thick film according to claim 6, characterized in that, The flux includes B2O3 and PbO, and the molar ratio of PbO to B2O3 is (1 to 15):

1.

8. The preparation method of the cerium-doped yttrium iron garnet single crystal thick film according to claim 5, characterized in that, The step of heating the raw material mixture to melting and then holding it to obtain a molten raw material includes: Heating the raw material mixture to 1050°C - 1250°C and holding it, and rotating the raw material mixture at a speed of 10 to 60 rpm while heating.

9. The preparation method of the cerium-doped yttrium iron garnet single crystal thick film according to claim 5, wherein After cooling the molten raw material, dipping a substrate into the molten raw material to grow a single crystal thick film includes: After cooling the temperature of the molten raw material to the supersaturation temperature, dipping a substrate into the molten raw material and holding it for 30 min to 90 min.

10. The preparation method of the cerium-doped yttrium iron garnet single crystal thick film according to claim 9, characterized in that, After the step of cooling the molten raw material, dipping a substrate into the molten raw material to grow a single crystal thick film to obtain a cerium-doped yttrium iron garnet single crystal thick film, it further includes: Performing a hot bath on the cerium-doped yttrium iron garnet single crystal thick film in an aqueous nitric acid solution, where the hot bath temperature is 60°C to 130°C and the hot bath time is 30 min to 120 min.

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