Low coercivity YIG substrate material for LTCC circulator and preparation method thereof

Abstract

A low coercivity YIG substrate material for LTCC circulator and a preparation method thereof, belonging to the technical field of electronic ceramics. The present invention adopts Bi-Li-P combined substitution and introduces Bi 3+ , Li + , P 5+ Ion substitution of Y at 24c in YIG 3+ ions, Fe at positions 16a and 24d 3+ ions, resulting in significant lattice distortion, which greatly reduces the sintering temperature of the material, reducing the solid phase reaction broadening component in the ferromagnetic resonance line width of the sample. + , P 5+ The amount of ion substitution controls the ferrite grain growth and pore exclusion during the sintering process, so that the material obtains multiple dense microstructures; on the one hand, it is beneficial to increase the bulk density of the material and reduce the porosity, while obtaining a high saturation magnetization intensity and reducing the pore width in the ferromagnetic resonance line width; on the other hand, the increase in the average grain size of the material is beneficial to reducing the coercive force of the material.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic ceramics, and in particular relates to a low-coercive force YIG substrate material for LTCC circulator and a preparation method thereof. Background Art

[0002] YIG ferrite materials are widely used in the production of microwave circulator substrate materials due to their low coercivity and ferromagnetic resonance linewidth, high saturation magnetization, and good temperature stability. In recent years, microwave ferrite devices have gradually developed in the direction of light weight and high integration, and an important means to achieve this development direction is to use low-temperature co-fired ceramic technology (LTCC), which requires the sintering temperature of YIG materials (≤930℃). As the key substrate material for X-band circulators, how to make YIG ferrite materials at low temperatures and have good gyromagnetic properties (low coercivity, high saturation magnetization, low ferromagnetic resonance linewidth, and high Curie temperature) is an urgent problem to be solved.

[0003] At present, the research on low temperature sintering and gyromagnetic properties of YIG materials mainly focuses on ion substitution. The invention patent with application number 202110324952.9 discloses a preparation method of low temperature sintered YIG gyromagnetic ferrite material, which introduces Bi 3+ 、V 5+ 、Zn 2+ Three ions were used to obtain a single garnet phase at 930°C. The material properties are as follows: saturation magnetization 1485-1625Gs, ferromagnetic resonance line width 389Oe-607Oe, and coercivity 17-18Oe. The material line width and coercivity obtained by this method are relatively high, and no report on Curie temperature is involved. "R.Fu, YXLi et al. High Dielectric Constant YIG Ferrites with Low Sintering Temperature [J]. Journal of Materials Science-Materials in Electronics, 2022, 5: 4914-4923." The article uses Bi 3+ Ions and Ca 2+ Ion substitution of dodecahedral c-position (24c)Y 3+ ions, using Sn 4+ Ions and Zr 4+ Ion substitution of Fe at the octahedral site (16a) 3+ions, the study reduced the YIG sintering temperature to 960℃, the material properties are as follows: saturation magnetization 1756~1843Gs, ferromagnetic resonance line width 190~230Oe, the material sintering temperature of this method is relatively high, and there is no report on coercivity and Curie temperature. "CYTsay. Low temperature sintering of microwave magnetic garnet materials[J].Journal of Magnetism and Magnetic Materials,2002,29(11):490-494." The article uses Ca 2+ Ion substitution for dodecahedral c-position (24c), V 5+ Ions replace the tetrahedral position (24d) and the YIG material is prepared at 1250℃. 3+ Ions replace the c-site (24c) of the dodecahedron and reduce the sintering temperature to 1020°C. The performance of the material is as follows: saturation magnetization 1523Gs, ferromagnetic resonance line width 110Oe. The sintering temperature of the material prepared by this method is too high, and there is no report on coercivity and Curie temperature. In summary, in order to meet the needs of LTCC technology, it is necessary to explore new solutions to improve the comprehensive gyromagnetic properties of YIG materials (low coercivity, high saturation magnetization, low ferromagnetic resonance line width, high Curie temperature). Summary of the invention

[0004] The purpose of the present invention is to address the problems existing in the background technology and to propose a low coercive force YIG substrate material for LTCC circulator and a preparation method thereof.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A low coercivity YIG substrate material for LTCC circulators, with Bi 3+ , Li + , P 5+ Ion substitution of Y at 24c in YIG 3+ ions, Fe at positions 16a and 24d 3+ ions, Bi-Li-P combined substitution produces significant lattice distortion, which greatly reduces the sintering temperature of the YIG material. At the same time, the solid-phase reaction of the sample completely reduces the solid-phase reaction broadening component in the ferromagnetic resonance line width; and on this basis, the Li + , P 5+The amount of ion substitution controls the ferrite grain growth and pore removal during the sintering process, so that the sample obtains a dense multiple microstructure, which is beneficial to improving the bulk density of the material and reducing the porosity, while obtaining a high saturation magnetization intensity, reducing the pore width in the ferromagnetic resonance line width; on the other hand, the increase in the average grain size of the material is beneficial to reducing the coercive force of the material. The components of the YIG substrate material are: Fe2O3 44.39-45.75mol%, Y2O3 29.74-29.89mol%, Bi2O3 24.51-24.63mol%, P2O5 0.2-0.71mol%, and Li2CO3 0.1-0.37mol%.

[0007] A method for preparing a low coercive force YIG substrate material for a LTCC circulator comprises the following steps:

[0008] Step 1: Preparation of pre-burned materials:

[0009] 1.1 Take iron oxide (Fe2O3), yttrium oxide (Y2O3), bismuth trioxide (Bi2O3), phosphorus pentoxide (P2O5), and lithium carbonate (Li2CO3) as raw materials, weigh the raw materials according to the ratio of "Fe2O3 44.39-45.75mol%, Y2O3 29.74-29.89mol%, Bi2O3 24.51-24.63mol%, P2O5 0.2-0.71mol%, Li2CO3 0.1-0.37mol%", put them into a planetary ball mill for ball milling for 6-10h to obtain a primary ball mill material;

[0010] 1.2 Dry and sieve the primary ball mill obtained in step 1.1, and then place it in a calcination furnace for calcination in an oxygen atmosphere at a temperature of 800 to 850°C for 2.5 to 3.5 hours;

[0011] Step 2: Secondary ball milling:

[0012] The pre-sintered material obtained in step 1 is sieved and put into a planetary ball mill for secondary ball milling. The ball milling time is 10 to 12 hours. After the ball milling is completed, it is dried and sieved to obtain a second-milled powder;

[0013] Step 3: Molding and sintering:

[0014] 3.1 Add 8-12 wt% of polyvinyl alcohol binder to the second-milled powder obtained in step 2 for granulation, and then press it into a ring-shaped embryo sample using a hydraulic press;

[0015] 3.2 The green blank obtained in step 3.1 is placed in a sintering furnace for sintering, and the temperature is raised to 880-920°C at a rate of 1-3°C / min, and kept at this temperature for 2 hours. After sintering, the temperature is naturally lowered to obtain the YIG substrate material.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention significantly reduces the sintering temperature by replacing the activated lattice with Bi-Li-P. At the same time, the solid phase reaction completely reduces the solid phase reaction broadening component in the ferromagnetic resonance line width, which is beneficial to narrowing the line width.

[0018] 2. The present invention adjusts Li + , P 5+ The amount of ion substitution controls the ferrite grain growth and pore distribution during the sintering process, while ensuring high saturation magnetization intensity, reducing the pore width in the ferromagnetic resonance line width; and a larger average grain size is conducive to reducing the coercive force.

[0019] 3. In addition to having a relatively low sintering temperature (≤920°C), the YIG substrate material prepared by the present invention also has good gyromagnetic properties: low coercive force (Hc<10Oe), high saturation magnetization (4πMs>1600Gs), low ferromagnetic resonance line width (ΔH<260Oe), and high Curie temperature (Tc>300°C). The prepared substrate material not only meets the requirements of the LTCC process, but also has the excellent magnetic properties required for the substrate material for the circulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 SEM images of the YIG samples obtained in Comparative Example (a) and Example 1 (b);

[0021] Figure 2 This is the XRD spectrum of the YIG sample prepared in Example 1. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0023] Example 1

[0024] A method for preparing a low coercive force YIG substrate material for a LTCC circulator comprises the following steps:

[0025] Step 1: Preparation of pre-burned materials:

[0026] 1.1 Take iron oxide (Fe2O3), yttrium oxide (Y2O3), bismuth trioxide (Bi2O3), phosphorus pentoxide (P2O5), and lithium carbonate (Li2CO3) as raw materials, weigh the raw materials according to the ratio of "Fe2O3 45.07mol%, Y2O3 29.82mol%, Bi2O3 24.57mol%, P2O5 0.36mol%, Li2CO3 0.18mol%", put them into a planetary ball mill for 8h to obtain a primary ball mill;

[0027] 1.2 Dry and sieve the primary ball mill obtained in step 1.1, and then place it in a calcination furnace for calcination in an oxygen atmosphere at a temperature of 850°C for 3 hours;

[0028] Step 2: Secondary ball milling:

[0029] The pre-sintered material obtained in step 1 is sieved and put into a planetary ball mill for secondary ball milling. The ball milling time is 12 hours. After the ball milling is completed, it is dried and sieved to obtain a second-milled powder;

[0030] Step 3: Molding and sintering:

[0031] 3.1 Add 8-12 wt% of polyvinyl alcohol binder to the second-milled powder obtained in step 2 for granulation, and then press it into a ring-shaped embryo sample at a pressure of 10 MPa using a hydraulic press;

[0032] 3.2 The green blank obtained in step 3.1 is placed in a sintering furnace for sintering, the temperature is raised to 900°C at a rate of 2°C / min, and the temperature is kept for 2 hours. After the sintering is completed, the temperature is naturally lowered to obtain the YIG substrate material.

[0033] The properties of the circulator substrate material prepared in Example 1 are as follows: coercivity Hc 8.79Oe; saturation magnetization 4πMs1725Gs; ferromagnetic resonance line width ΔH 240Oe; Curie temperature Tc 320.1; density ρ5.51g / cm 3 .

[0034] Example 2

[0035] Compared with Example 1, the difference between this example and Example 1 is that in step 1.1, raw materials are weighed according to the ratio of "Fe2O3 44.90mol%, Y2O3 29.84mol%, Bi2O3 24.59mol%, P2O5 0.45mol%, Li2CO3 0.22mol%", and the other steps remain unchanged.

[0036] The properties of the circulator substrate material prepared in Example 2 are as follows: coercivity Hc 8.52Oe; saturation magnetization 4πMs1663Gs; ferromagnetic resonance line width ΔH 245Oe; Curie temperature Tc 318.3; density ρ5.46g / cm 3 .

[0037] Example 3

[0038] The present embodiment is different from the embodiment 1 in that the sintering temperature in step 3.2 is adjusted to 920° C., and the other steps remain unchanged.

[0039] The properties of the circulator substrate material prepared in Example 3 are as follows: coercivity Hc 8.63Oe; saturation magnetization 4πMs1730Gs; ferromagnetic resonance line width ΔH 260Oe; Curie temperature Tc 320.2; density ρ5.51g / cm 3 .

[0040] Comparative Example 1

[0041] Compared with Example 1, the difference between this comparative example and Example 1 is that in step 1.1, the raw materials are weighed according to the ratio of "Fe2O3 45.75mol%, Y2O3 29.74mol%, Bi2O3 24.51mol%, P2O5 0mol%, Li2CO3 0mol%", and the other steps remain unchanged.

[0042] The properties of the circulator substrate material prepared in Comparative Example 1 are as follows: coercivity Hc 14.45Oe; saturation magnetization 4πMs1500Gs; ferromagnetic resonance line width ΔH 936Oe; Curie temperature Tc 325.6; density ρ5.22g / cm 3 .

[0043] Comparative Example 2

[0044] The difference between this comparative example and Example 1 is that in step 1.1, the raw materials are weighed according to the ratio of "Fe2O3 44.35mol%, Y2O3 29.71mol%, Bi2O3 24.65mol%, P2O5 0.86mol%, Li2CO3 0.43mol%", and the other steps remain unchanged.

[0045] The properties of the circulator substrate material prepared in Comparative Example 2 are as follows: coercivity Hc 11.69Oe; saturation magnetization 4πMs1523Gs; ferromagnetic resonance line width ΔH 491Oe; Curie temperature Tc 316.3; density ρ5.06g / cm 3 .

[0046] Figure 1 SEM images of the YIG samples obtained in Comparative Example (a) and Example 1 (b); Figure 2 The XRD spectrum of the YIG sample obtained in Example 1 is shown in FIG. Figure 1 It can be seen that after the Bi-Li-P joint substitution, the grains of the material present a multiple structure, and the average grain size increases significantly, making the sample have a low coercive force. Figure 2 It can be seen that the sample prepared by the present invention is a single garnet phase. Table 1 is a comparison table of magnetic properties of comparative examples and examples. 3+ , Li + , P 5+ Ion substitution of Y at 24c in YIG 3+ions, Fe at positions 16a and 24d 3+ ions, the resulting lattice distortion causes the YIG material sintering temperature to drop significantly. + , P 5+ The amount of ion substitution enables the sample to obtain a dense structure, which is beneficial to improving the density of the material and reducing the porosity of the material, ensuring that the material has a high saturation magnetization intensity while reducing the pore widening in the ferromagnetic resonance line width.

[0047] Table 1: Comparison table of material properties of comparative examples and examples

[0048]

Claims

1. A low coercive force YIG substrate material for LTCC circulator, characterized in that: The components of the YIG substrate material are: Fe2O3 44.39-45.75mol%, Y2O3 29.74-29.89mol%, Bi2O3 24.51-24.63mol%, P2O5 0.2-0.71mol%, and Li2CO3 0.1-0.37mol%.

2. A method for preparing a low coercive force YIG substrate material for LTCC circulator, characterized in that: The following steps are involved: Step 1: Preparation of pre-burned materials: 1.1 Take Fe2O3, Y2O3, Bi2O3, P2O5 and Li2CO3 as raw materials, weigh the raw materials according to the ratio of "Fe2O3 44.39-45.75mol%, Y2O3 29.74-29.89mol%, Bi2O3 24.51-24.63mol%, P2O5 0.2-0.71mol%, Li2CO3 0.1-0.37mol%", put them into a planetary ball mill for 6-10h to obtain a primary ball mill; 1.2 Dry and sieve the primary ball mill obtained in step 1.1, and then pre-calculate it in an oxygen atmosphere at a temperature of 800-850°C for 2.5-3.5 hours; Step 2: Secondary ball milling: The pre-sintered material obtained in step 1 is sieved and then ball-milled for a second time for 10 to 12 hours. After the ball-milling is completed, it is dried and sieved to obtain a second-milled powder; Step 3: Molding and sintering: 3.1 Add polyvinyl alcohol binder to the second-milled powder obtained in step 2 for granulation, and then press into blanks; 3.2 The green blank obtained in step 3.1 is placed in a sintering furnace for sintering, and the temperature is raised to 880-920°C at a rate of 1-3°C / min, and kept at this temperature for 2 hours. After sintering, it is naturally cooled to room temperature to obtain the YIG substrate material.

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