Double-ferrite heterogeneous co-fired composite substrate material and preparation method thereof

Abstract

The invention belongs to the field of microwave devices and electronic materials, and discloses a double-ferrite heterogeneous co-fired composite substrate material and a preparation method thereof.The double-ferrite heterogeneous co-fired composite substrate material comprises central ferrite and external nested ferrite, the central ferrite is NiZn ferrite substituted by Cu < 2 + > ions, and the external nested ferrite is NiZn ferrite substituted by Cu < 2 + > ions. The central ferrite is YIG microwave ferrite, the external nested ferrite is YIG microwave ferrite substituted by Bi < 3 + > ions, the central ferrite and the external nested ferrite are compounded through co-firing, and the sintering temperature adopted for co-firing is 1100-1150 DEG C. According to the preparation method, Cu < 2 + > ions are introduced into the NiZn ferrite to generate partial substitution, so that co-firing matching of two heterogeneous ferrite materials, namely the NiZn ferrite and the YIG microwave ferrite, which are relatively large in sintering temperature difference and unmatched in shrinkage characteristics is successfully realized, and the NiZn-YIG ferrite co-fired composite substrate of which the outer ring is not cracked and even is relatively high in bonding quality is obtained; and the method has great potential application value in the field of broadband miniaturization of circulators.

Description

Technical Field

[0001] This invention belongs to the field of microwave devices and electronic materials, and more specifically, relates to a dual ferrite heterogeneous co-fired composite substrate material and its preparation method. The dual ferrite heterogeneous co-fired composite substrate material can be used to form a heterogeneous core-ring co-fired composite circulator. Background Technology

[0002] For decades, microwave ferrite devices primarily employed single-ferrite substrates. However, with the advancement of miniaturization, lightweighting, and broadband communication technologies in the 5G era, the limitations of designs based on single-ferrite materials have become increasingly apparent, hindering further miniaturization and broadband scaling of devices. This has given rise to dielectric ceramic-ferrite and ferrite-ferrite composite substrate designs. These designs can meet the demands for device miniaturization, lightweighting, and wideband response, opening a new chapter for composite substrates. The composite substrate consists of a cylindrical inner core made of high-saturation magnetization ferrite and an outer ring of low-saturation magnetization ferrite or non-magnetic dielectric ceramic. The interface between the cylinder and the ring in this composite substrate forms a perimeter mode. The magnetic field distribution of this anomalous mode exhibits a relatively stable field structure over a wide frequency range, enabling the application of such devices in overclocking circulators.

[0003] Based on the substrate connection method, composite substrates can be divided into bonded composite substrates and co-fired composite substrates. While adhesive bonding is relatively simple, it has significant drawbacks: i) epoxy resin, as an organic material, has poor aging resistance, leading to poor substrate temperature stability and short service life; ii) interface binders can severely affect circulator performance, for example, insertion loss may deteriorate. Directly co-firing microwave dielectric ceramic or ferrite ceramic rings with ferrite cores avoids the drawbacks of using binders in circulators. However, this connection method first requires solving the co-firing matching problem of the two materials (mainly including matching the sintering temperature and shrinkage characteristics of the heterogeneous ceramics), and also requires solving the problem of tight bonding and extremely low ion diffusion at the heterogeneous interface after co-firing; otherwise, cracking and deterioration of electromagnetic performance will occur, affecting practical applications. Therefore, solving both problems simultaneously is extremely difficult. Based on the above, achieving matching of sintering temperature and shrinkage characteristics of heterogeneous materials, as well as tight bonding and low ion interdiffusion rate at the interface, are the key technical requirements for realizing heterogeneous composite co-fired circulator substrates.

[0004] Heterogeneous co-fired composite substrates made of dual ferrite materials are beneficial for reducing the Fe content in the ferrite core, which has an extremely high Fe content. 3+The diffusion of ions affects the outer ring of the dielectric ceramic, which contributes to the stability of the overall electric field performance of the co-fired composite substrate. NiZn ferrite exhibits a stronger gyromagnetic effect due to its high saturation magnetization, which is crucial for miniaturizing circulators; while YIG materials possess superior dielectric properties and lower electromagnetic losses, which are also important for improving isolation performance and achieving circulator miniaturization. Pure YIG materials (Y3Fe5O3) are well-known in the art. 12 The sintering temperature of NiZn ferrite materials is generally higher than 1400 ℃, while that of pure NiZn ferrite materials (Ni x Zn 1-x Fe2O4, where 0.1 ≤ x ≤ 0.9, for example, x = 0.2, 0.4, etc.) The sintering temperature is generally between 1100 and 1250 ℃. Therefore, achieving co-firing of the two requires lowering the sintering temperature of YIG and matching the shrinkage characteristics of both. Lowering the sintering temperature of YIG to 1100-1250 ℃ usually requires active ions (such as Bi) 3+ The liquid-phase sintering achieved by ion substitution accelerates the rate of change in shrinkage. However, NiZn-based ferrites, sintered at 1100–1250 °C, generally do not rely on liquid-phase sintering, resulting in a relatively low rate of change in shrinkage. This mismatch in shrinkage characteristics leads to a higher risk of outer ring cracking during co-firing. Furthermore, at 1100–1250 °C, the shrinkage rate of NiZn ferrites is typically lower than that of Bi-based ferrites. 3+ The yield rates of ion-substituted YIG-based ferrites vary considerably, which can also lead to the presence of Bi. 3+ Cracking of the outer ring of ion-substituted YIG-based ferrites. Therefore, lower-temperature NiZn-based ferrites with Bi... 3+ The key to co-firing matching of ion-substituted YIG-based ferrites lies in solving the problem of matching their shrinkage characteristics, especially the matching of shrinkage rate change rate and shrinkage rate. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a dual ferrite heterogeneous co-fired composite substrate material and its preparation method, by introducing Cu into NiZn-based ferrite. 2+ Partial substitution by ion generation successfully achieved co-firing matching of two heterogeneous ferrite materials—NiZn-based ferrite and YIG-based microwave ferrite—which have significantly different sintering temperatures and mismatched shrinkage characteristics. This invention combines NiZn-based ferrite with Bi... 3+ Heterogeneous co-firing composites of ion-substituted YIG-based microwave ferrites, especially those with different Cu ratios, are possible. 2+ Ion substitution enables gradual and controllable adjustment of the shrinkage rate of NiZn ferrite, while simultaneously increasing its shrinkage rate change rate, thus solving the problem of Bi...3+ The problem of cracking in the outer ring of ion-substituted YIG-based ferrite has been addressed by preparing NiZn-YIG-based ferrite co-fired composite substrates with crack-free outer rings or even high bonding quality. This has great potential application value in the field of broadband miniaturization of circulators.

[0006] To achieve the above objectives, according to one aspect of the present invention, a dual-ferrite heterogeneous co-fired composite substrate is provided, comprising a central ferrite and an outer nested ferrite, characterized in that the central ferrite is Cu. 2+ Ion-substituted NiZn-based ferrites, wherein the outer nested ferrite is Bi 3+ The ion-substituted YIG-based microwave ferrite, wherein the central ferrite and the outer nested ferrite are co-fired together, and the sintering temperature used for co-firing is 1100 ~ 1150 ℃.

[0007] As a further preferred embodiment of the present invention, the Cu 2+ Ion-substituted NiZn ferrites have the general chemical formula Ni 1-a-b Zn b Cu a Fe2O4, of which 0.00

[0008] The Bi 3+ Ion-substituted YIG-based microwave ferrites, with the general chemical formula Yi... 3-c-d Bi d Al c Fe5O 12 , of which 0.0 <c ≤ 0.5,0.0<d ≤ 0.5。

[0009] As a further preferred embodiment of the present invention, the outer nested ferrite is a hollow circular annular ferrite or a hollow square ferrite, nested outside the central ferrite.

[0010] According to another aspect of the present invention, the present invention provides a method for preparing the above-mentioned dual ferrite heterogeneous co-fired composite substrate, characterized by comprising the following steps: (1) Using NiO powder, ZnO powder, CuO powder, Fe2O3 powder, Bi2O3 powder, Y2O3 powder, and Al2O3 powder as raw materials, respectively according to the general chemical formula Ni 1-a-b Zn b Cu a Fe2O4 and Y 3-c-d Bi d Al c Fe5O 12 ​The nominal stoichiometric ratio of the metallic elements in the raw materials is used to form NiZn-based ferrite mixed powder and YIG-based ferrite mixed powder; wherein, 0.00 (2) The NiZn-based ferrite mixed powder and the YIG-based ferrite mixed powder are respectively subjected to wet ball milling to obtain NiZn-based ferrite primary ball milling slurry and YIG-based ferrite primary ball milling slurry. (3) The ball mill slurry obtained in step (2) is dried, passed through a 40-80 mesh sieve, and pre-calcined to obtain NiZn-based ferrite pre-calcined powder and YIG-based ferrite pre-calcined powder; wherein, each type of pre-calcined powder is kept at a pre-calcination temperature of 850-950 ℃ for 2-4 h. (4) The pre-calcined powder obtained in step (3) is subjected to wet ball milling to obtain NiZn ferrite secondary ball milling slurry and YIG ferrite secondary ball milling slurry. (5) The secondary ball mill slurry obtained in step (4) is dried, passed through a 40-80 mesh sieve, and granulated by adding a binder to obtain NiZn ferrite granulated powder and YIG ferrite granulated powder. (6) Place the NiZn ferrite granulated powder obtained in step (5) into a mold and press it to obtain a NiZn ferrite cylindrical green body. (7) Using the cylindrical green body obtained in step (6) as the core mold, the YIG ferrite granulated powder obtained in step (5) is placed into the matching external nested mold for pressing and molding to obtain NiZn-YIG ferrite composite green body. (8) The NiZn-YIG ferrite composite green body obtained in step (7) is subjected to debinding treatment; (9) The NiZn-YIG ferrite composite green blank obtained in step (8) is placed in an air atmosphere in a sintering furnace for co-sintering at a sintering temperature of 1100 ~ 1150 ℃, thereby obtaining a dual ferrite heterogeneous co-fired composite substrate.

[0011] As a further preferred embodiment of the present invention, in step (6), the molding pressure used for pressing is 100 ~ 150 MPa, and the holding time is 30 ~ 60 s; In step (7), the molding pressure used for pressing is 150 ~ 200 MPa, and the holding time is 30 ~ 60 s.

[0012] As a further preferred embodiment of the present invention, in step (8), the glue removal temperature used in the glue removal process is 400~500 ℃. ​

[0013] As a further preferred embodiment of the present invention, in step (6), the diameter of the cylindrical green blank is 5.27 mm; In step (7), the outer nested mold is used to form a hollow annular structure with an inner diameter of 5.27 mm and an outer diameter of 11 mm.

[0014] According to another aspect of the present invention, the present invention provides the application of the above-described dual ferrite heterogeneous co-fired composite substrate in circulators or isolators.

[0015] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following beneficial effects: The sintering temperature of pure YIG materials is generally higher than 1400 ℃, while the sintering temperature of pure NiZn materials is generally between 1100 and 1250 ℃. This significant difference in sintering temperature, coupled with the mismatch in their shrinkage characteristics, makes co-firing difficult. This invention addresses this issue by introducing Cu into NiZn-based ferrites. 2+ Partial substitution by ions effectively regulates the sintering temperature and shrinkage characteristics of NiZn-based ferrites, allowing NiZn-based ferrites to combine with Bi... 3+ Ion-substituted YIG-based microwave ferrites can be co-fired at sintering temperatures of 1100~1150 ℃.

[0016] Based on this invention, a NiZn-YIG ferrite co-fired composite substrate with tight heterogeneous interface bonding and extremely low ion interdiffusion rate can be prepared, which has great potential application value in the field of broadband miniaturization of circulators. Taking the following embodiments as examples, this invention uses a sintering temperature of 1100~1150 ℃... M s = 20.2 emu / g, with excellent dielectric properties, such as Bi 3+ Ion-substituted YIG-based ferrites, acting as outer nested rings, enhance high saturation magnetization. M s A NiZn-based ferrite with a density of 76.2 emu / g was used as the central ferrite cylinder of the composite substrate, and Cu was used to... 2+ Ion substitution of NiZn ferrite modulates its shrinkage matching characteristics and sintering process, thereby effectively realizing the synthesis of NiZn ferrite and Bi-containing ferrite. 3+ The sintering process and shrinkage characteristics of ion-substituted YIG-based ferrites are matched, and the Fe content of the inner core ferrite material is reduced by using a dual-ferrite material. 3+The influence of ion diffusion on the electromagnetic properties of the outer ring of the dielectric was investigated. By forming the NiZn-YIG ferrite composite green blank through co-pressing, the heterogeneous co-fired composite substrate maintained extremely low ion interdiffusion while achieving a tight bond, with a maximum diffusion width of only 5.89 μm. This is beneficial for maintaining the excellent electromagnetic properties of the composite substrate and improving the reliability of the device. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the NiZn-YIG composite substrate sample preparation method of the present invention.

[0018] Figure 2 The XRD patterns are shown for the YIG ferrite monomers and NiZn ferrite monomers prepared according to the methods of Examples 1-3 and Comparative Example 1; wherein, Figure 2 (a) in the text corresponds to different Cu 2+ NiZn ferrite with varying ion substitution ratio; Figure 2 (b) in the text corresponds to YIG ferrite.

[0019] Figure 3 The graph shows the shrinkage rate and shrinkage rate variation of the YIG ferrite monomers prepared according to the preparation methods of Examples 1-3 and Comparative Example 1, and the NiZn ferrite monomers prepared according to the preparation methods of Examples 3 and Comparative Example 1; wherein, Figure 3 (a) in the figure corresponds to the change in shrinkage rate with temperature; Figure 3 (b) in the figure corresponds to the change in shrinkage rate with temperature.

[0020] Figure 4 The images show actual samples of NiZn-YIG ferrite core-ring heterogeneous co-fired composite substrates from Examples 1-3 and Comparative Example 1.

[0021] Figure 5 The images show the SEM image and elemental EDS mapping of the heterostructure interface of the NiZn-YIG ferrite core-ring heteroco-fired body prepared in Example 3; wherein, Figure 5 (a) in the image corresponds to the SEM image. Figure 5 (b) in the diagram corresponds to the Fe element EDS Mapping diagram. Figure 5 (c) in the diagram corresponds to the Ni element EDS Mapping diagram. Figure 5 (d) in the graph corresponds to the Zn element EDS Mapping graph. Figure 5 (e) in the diagram corresponds to the Cu element EDS Mapping. Figure 5 (f) in the diagram corresponds to the Y element in the EDS Mapping graph. Figure 5 (g) in the diagram corresponds to the Bi element EDS Mapping diagram. Figure 5(h) in the figure corresponds to the EDS Mapping diagram of Al element; the “transition region” in the figure is the bonding region between YIG ferrite and NiZn ferrite (NZFC), and the width of the “transition region” shown in the figure is about 15 μm.

[0022] Figure 6 The image shows the elemental EDS diagram and diffusion coefficient diagram of the heterostructure interface of the NiZn-YIG ferrite core-ring heterostructure prepared in Example 3; wherein, Figure 6 (a) in the image is a SEM image. Figure 6 (b) in the figure is the element line EDS plot corresponding to the SEM plot. Figure 6 (c) in the figure is the diffusion coefficient diagram at different diffusion distances (diffusion distance starts from 0 and goes to the farthest diffusion distance).

[0023] Figure 7 The images show the physical sample of Example 3 and the shrinkage rate of NiZn ferrite monomer and YIG ferrite monomer prepared according to the preparation method of Example 3 as a function of temperature. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] The dual-ferrite heterogeneous co-fired composite substrate of this invention uses NiZn-based ferrite as the central ferrite of the composite substrate and YIG-based ferrite as the outer nested ring. The general chemical formula of the NiZn-based ferrite is Ni... 1-a- b Zn b Cu a Fe2O4, 0.00 3-c- d Bi d Al c Fe5O 12 0.0 <c ≤ 0.5,0.0<d ≤ 0.5。

[0026] The corresponding preparation methods, such as Figure 1 As shown, the following steps may be included: (1) Formulation of NiZn-based and YIG-based ferrite powders: According to the chemical formula Ni 1-a-b Zn b Cu​a Fe2O4 and Y 3-c- d Bi d Al c Fe5O 12 The nominal stoichiometric ratio of metal elements in ferrite powder was calculated, and the masses of various raw materials were weighed to obtain Ni. 1-a-b Zn b Cu a Fe2O4 mixed powder and Y 3-c-d Bi d Al c Fe5O 12 Mixed powder; wherein the raw materials are NiO, ZnO, CuO, Fe2O3, Bi2O3, Y2O3, and Al2O3; 0.00 (2) First ball milling of NiZn-based and YIG-based ferrite powders: The two mixed powders obtained in step (1) are ball milled once (i.e., the corresponding mixed powders are placed in a ball mill jar with zirconium balls and dispersant and mixed evenly in a ball mill). The ball milling time for each mixed powder is 4 to 6 hours, and a ball mill slurry is obtained. The ball milling method used is wet ball milling, and the dispersant is water. (3) Pre-calcination of NiZn-based and YIG-based ferrite powders: The two slurries obtained in step (2) are dried and passed through a 40-80 mesh sieve. The NiZn-based ferrite powder and YIG-based ferrite powder after sieving are placed in a sintering furnace in an air environment for pre-calcination. The pre-calcination temperature is 850-950 ℃, and the pre-calcination holding time for each powder is 2-4 h, so as to obtain pre-calcined powders. (4) Secondary ball milling of NiZn-based and YIG-based ferrite powders: The pre-calcined powders obtained in step (3) are placed in ball mill jars and mixed with zirconium balls and dispersant. The mixture is then placed on a ball mill and mixed evenly. The ball milling time for each powder is 6 to 8 hours to obtain secondary ball milling slurry. The ball milling method used is wet ball milling, and the dispersant is water. (5) Granulation of NiZn-based and YIG-based ferrite powders: The ball mill slurry obtained in step (4) is dried and passed through a 40-80 mesh sieve to form powder. A binder is added for granulation to obtain granulated powder. The binder is PVA (containing 5wt% and 10wt%). During granulation, 4ml of 10wt% PVA is used for every 20g of NiZn-based powder, and 4ml of 5wt% PVA is used for every 20g of YIG-based powder. ​(6) NiZn ferrite cylinder molding: The NiZn ferrite particles obtained in step (5) are placed into a mold and pressed. The molding pressure is 100 ~ 150 MPa and the holding time is 30 ~ 60 s to obtain a cylindrical green blank with a diameter of Φ5.27 mm. (7) Forming of NiZn-YIG ferrite composite green body: The cylindrical green body with Φ5.27 mm obtained in step (6) is used as the core mold, and a YIG outer ring with Φ11 mm is formed at 150 ~ 200 MPa through the matching outer ring mold to make NiZn-YIG ferrite composite green body. (8) Removal of adhesive from NiZn-YIG ferrite composite substrate: Place the NiZn-YIG ferrite composite green blank obtained in step (7) in a sintering furnace and keep it at 400 ~ 500 ℃ in an air atmosphere for 4 ~ 5 h to remove the PVA colloid added during granulation.

[0027] (9) Sintering of NiZn-YIG ferrite composite substrate: The NiZn-YIG ferrite composite green blank obtained in step (8) after debinding is sintered in air at 1100 ~ 1150 °C for 4 ~ 6 h to prepare NiZn-YIG core-ring co-fired composite substrate.

[0028] The NiZn-YIG composite substrate sample of the present invention is prepared by integral molding into a NiZn-YIG composite green blank, which is conducive to the tight bonding of the NiZn-YIG bonding interface and avoids the problems of low efficiency and low success rate of manual assembly of NiZn-YIG composite green blank.

[0029] The general formula NiZn-based ferrites in the following embodiments and Comparative Example 1 are Ni 1-a-b Zn b Cu a Fe2O4 and YIG-based ferrites have the general formula Y 3-c-d Bi d Al c Fe5O 12 The values ​​of a, b, c, and d are set as shown in Table 1: Table 1

[0030] The following are specific examples: Example 1 In this embodiment, the NiZn-YIG dual ferrite heterogeneous co-fired composite substrate uses NiZn ferrite as the inner core ferrite of the composite substrate and YIG ferrite as the outer nested ring.

[0031] The general chemical formulas of the NiZn-based and YIG-based ferrites are Ni1-a-b Zn b Cu a Fe2O4 and Y 3-c- d Bi d Al c Fe5O 12 The values ​​of a, b, c, and d are shown in Table 1.

[0032] The method for preparing the NiZn-YIG dual ferrite heterogeneous co-fired composite substrate in this embodiment specifically includes the following steps: (1) Formulation of NiZn-based and YIG-based ferrite powders: According to the chemical formula Ni 1-a-b Zn b Cu a Fe2O4 and Y 3-c- d Bi d Al c Fe5O 12 The nominal stoichiometric ratios of the metal elements in Ni were calculated and various raw materials were weighed to obtain Ni. 1-a- b Zn b Cu a Fe2O4 mixed powder and Y 3-c-d Bi d Al c Fe5O 12 Mixed powder; wherein the raw materials are NiO, ZnO, CuO, Fe2O3, Bi2O3, Y2O3, and Al2O3; (2) First ball milling of NiZn-based and YIG-based ferrite powders: The two mixed powders obtained in step (1) are ball milled once (i.e., the corresponding mixed powders are placed in a ball mill jar with zirconium balls and dispersant and mixed evenly in a ball mill). The ball milling time for each mixed powder is 6 h, and a ball mill slurry is obtained. The dispersant is water. (3) Pre-calcination of NiZn-based and YIG-based ferrite powders: The two slurries obtained in step (2) are dried and passed through 40 and 80 mesh sieves respectively. Then, the NiZn-based ferrite powder and YIG-based ferrite powder after sieving are placed in a sintering furnace in an air environment for pre-calcination. The pre-calcination temperatures are 900 ℃ and 950 ℃ respectively. The pre-calcination holding time for each powder is 3 h to obtain pre-calcined powder. (4) Secondary ball milling of NiZn-based and YIG-based ferrite powders: The pre-calcined powders obtained in step (3) are placed in ball milling jars and mixed with zirconium balls and dispersant, and then placed on a ball mill for ball milling. The ball milling time for each powder is 8 h to obtain secondary ball milling slurry; wherein, the dispersant is water; (5) Granulation of NiZn-based and YIG-based ferrite powders: The ball mill slurry obtained in step (4) is dried and passed through an 80-mesh sieve to form powder. A binder is added for granulation to obtain granulated powder. The binder is PVA. During granulation, 4 ml of 10 wt% PVA is used for every 20 g of NiZn-based powder, and 4 ml of 5 wt% PVA is used for every 20 g of YIG-based powder. (6) NiZn ferrite cylinder molding: The NiZn ferrite particles obtained in step (5) are placed into a mold and pressed. The molding pressure is about 125 MPa and the holding time is 40 s to obtain a cylindrical blank with a diameter of Φ5.27 mm. (7) Forming of NiZn-YIG ferrite composite green body: The cylindrical green body with Φ5.27 mm obtained in step (6) is used as the core mold, and a YIG outer ring with Φ11 mm is formed at 150 MPa through the matching outer ring mold to make NiZn-YIG ferrite composite green body. (8) Removal of adhesive from NiZn-YIG ferrite composite substrate: Place the NiZn-YIG ferrite composite green blank obtained in step (7) in a sintering furnace and keep it at 400 ℃ in an air atmosphere for 4 h to remove the adhesive added during granulation.

[0033] (9) Sintering of NiZn-YIG ferrite composite substrate: The NiZn-YIG ferrite composite green blank obtained in step (8) after debinding was sintered in air at 1125 °C for 6 h to prepare NiZn-YIG composite co-fired body.

[0034] Example 2 In this embodiment, the NiZn-YIG dual ferrite heterogeneous co-fired composite substrate uses NiZn ferrite as the inner core ferrite of the composite substrate and YIG ferrite as the outer nested ring.

[0035] The general chemical formulas of the NiZn-based and YIG-based ferrites are Ni 1-a-b Zn b Cu a Fe2O4 and Y 3-c- d Bi d Al c Fe5O 12 The values ​​of a, b, c, and d are shown in Table 1.

[0036] Except for the change in ingredients in step (1), the preparation method is the same as in Example 1.

[0037] Example 3 In this embodiment, the NiZn-YIG dual ferrite heterogeneous co-fired composite substrate uses NiZn ferrite as the inner core ferrite of the composite substrate and YIG ferrite as the outer nested ring.

[0038] The general chemical formulas of the NiZn-based and YIG-based ferrites are Ni 1-a-b Zn b Cu a Fe2O4 and Y 3-c- d Bi d Al c Fe5O 12 The values ​​of a, b, c, and d are shown in Table 1.

[0039] Except for the change in ingredients in step (1), the preparation method is the same as in Example 1.

[0040] Comparative Example 1 The comparative example yields a NiZn-YIG dual ferrite heterogeneous co-fired composite substrate without Cu doping, with NiZn ferrite as the inner core ferrite of the composite substrate and YIG ferrite as the outer nested ring.

[0041] The general chemical formulas of the NiZn-based and YIG-based ferrites are Ni 1-a-b Zn b Cu a Fe2O4 and Y 3-c- d Bi d Al c Fe5O 12 The values ​​of a, b, c, and d are shown in Table 1.

[0042] Except for the change in the ingredients in step (1), the sintering temperature in step (9) is 1150 °C. All other steps are the same as in Example 1.

[0043] Performance testing: Following the preparation methods of Examples 1-3 and Comparative Example 1, YIG ferrite monomers and NiZn ferrite monomers were prepared under the component formulations and sintering processes corresponding to Examples 1-3 and Comparative Example 1, and their performance was tested. The results are shown in Table 2.

[0044] Table 2: Comparison of Material Properties

[0045] Meanwhile, the YIG ferrite monomers and NiZn ferrite monomers prepared according to the methods of Examples 1-3 and Comparative Example 1 were characterized by XRD, and the results are as follows. Figure 2As shown, it is not difficult to see that Cu 2+ The change in the amount of ion substitution did not cause any change in the phase structure of NiZn ferrite. At the same time, the decrease in sintering temperature from 1150 ℃ to 1125 ℃ did not cause any change in the phase structure of YIG main phase and NiZn or the generation of new phases. Both YIG main phase and NiZn ferrite phase remained the original phases. This stability of phase structure is conducive to maintaining the original excellent electromagnetic properties of the two ferrites.

[0046] Furthermore, based on the requirements for standard samples for shrinkage rate testing, the YIG ferrite monomer test standards prepared according to the preparation methods of Examples 1-3 and Comparative Example 1, and the NiZn ferrite monomer test standards prepared according to the preparation methods of Examples 3 and Comparative Example 1, were used to test the shrinkage rate of these samples using a thermal expansion analyzer (NETZSCH DIL402C, Germany) with a heating rate of 5℃ / min. The results are as follows: Figure 3 As shown; where, Figure 3 (a) in the figure corresponds to the change in shrinkage rate with temperature; Figure 3 (b) in the figure corresponds to the change in the rate of shrinkage with temperature. It is easy to see from this that, compared to Cu-free… 2+ Regarding the shrinkage characteristics of ion-substituted NiZn ferrites, when Cu 2+ When the ion substitution amount is 0.05 (corresponding to Example 3), the shrinkage characteristics of NiZn ferrite are significantly improved. The shrinkage initiation temperature is advanced, the rate of change of shrinkage is closer to that of YIG, and the final shrinkage is also closer to that of YIG. These optimizations increase the matching with the shrinkage characteristics of YIG, which is more conducive to their tight bonding and crack prevention. The shrinkage rate of NiZn ferrite monomers and YIG ferrite monomers prepared according to the preparation method of Example 3 changes with temperature, as follows: Figure 7 As shown.

[0047] On the other hand, regarding the heterogeneous co-fired composite substrates prepared in Examples 1-3 and Comparative Example 1, Figure 4 The images shown are physical samples of NiZn-YIG ferrite core-ring heterogeneous co-fired composite substrates from Examples 1-3 and Comparative Example 1. It is clear from these images that the sample prepared in Comparative Example 1 exhibits obvious cracking in the outer ring; while when Cu... 2+ When the ion substitution amount is 0.2 (corresponding to Example 1), the shrinkage characteristics of NiZn ferrite are altered, preventing cracking of the outer ring (although the interfacial reaction is relatively severe and the bonding is not very tight); furthermore, when Cu 2+ When the ion substitution amount is 0.1 (corresponding to Example 2), it can be clearly seen that the cracking of the outer ring is also avoided, and the interface reaction is reduced, resulting in improved sintering quality of NiZn ferrite (although its interface is still not very tight); while when Cu 2+When the ion substitution amount is 0.05 (corresponding to Example 3), it can be clearly seen that the cracking of the outer ring is also avoided, and the reaction at the bonding interface is minimal. The sintering quality of NiZn ferrite is improved, its bonding interface is tightly bonded and clearly demarcated, and the overall bonding quality of the NiZn-YIG ferrite core-ring heterogeneous co-fired composite substrate is improved.

[0048] The performance test results and composite conditions of the heterogeneous co-fired composite substrates prepared in Examples 1 to 3 and Comparative Example 1 are shown in Table 3.

[0049] Table 3: Composite configuration of heterogeneous co-fired composite substrates

[0050] Note: i. Prepare a NiZn-based cylindrical green blank according to step (6) of each embodiment or comparative example, and record the diameter of the green blank as Φ1; sinter the NiZn-based monomer according to the sintering process of the corresponding embodiment or comparative example, and record its diameter as Φ2. Then, the shrinkage rate of NiZn-based ferrite = 100%×(Φ1-Φ2) / Φ1; ii. Prepare YIG outer ring monomer green blanks separately according to step (7) of each embodiment or comparative example (at this time, a cylindrical solid mold of metal material with a diameter of 5.27 mm is used as the core mold), and record the inner diameter of the YIG outer ring monomer green blank as Φ3; sinter the YIG outer ring monomers according to the sintering process of the corresponding embodiment or comparative example, and record its inner diameter as Φ4. Then, the shrinkage rate of YIG ferrite = 100%×(Φ3-Φ4) / Φ3; The values ​​of Φ1, Φ2, Φ3, and Φ4 were all measured under normal temperature and pressure conditions.

[0051] Figure 5 The image shown is a SEM image and elemental EDS mapping of the heterostructure interface of the NiZn-YIG ferrite core-ring heteroco-fired body prepared in Example 3. From... Figure 5 As can be seen from (a) in the image, the micron-level heterogeneous interface is tightly bonded and clearly demarcated, confirming that the heterogeneous interface of the NiZn-YIG ferrite core-ring heterogeneous co-fired body achieves atomic-level bonding. From Figure 5 It is easy to see from (b) that both NiZn ferrite and YIG ferrite mainly contain Fe, which helps to reduce the impact of Fe diffusion. Figure 5 It is easy to see from (c)-(f) that the boundaries between Ni, Zn, Y, and Bi elements at the bonding interface are clear, indicating that the inter-ionic interdiffusion between the interfaces is extremely low. The contrast of Cu and Al elements is relatively dark, which also confirms that their interdiffusion is extremely low due to their extremely low content.

[0052] Figure 6The image shows the elemental EDS plot and diffusion coefficient diagram of the heterogeneous bonding interface of the NiZn-YIG ferrite core-ring heteropolymer prepared in Example 3. It is clear from the EDS mapping that, corroborated by the diagram, both the NiZn ferrite and YIG ferrite primarily contain Fe, which helps to reduce the influence of Fe diffusion. Furthermore, the gradient distribution of Ni, Zn, Y, and Bi elements at the bonding interface is extremely steep, indicating very low ion interdiffusion at the interface. Figure 6 The mass percentage distribution of the element shown in (b) was obtained by Boltzmann fitting and then calculated according to Fick's second law to obtain the diffusion coefficient as a function of diffusion distance. The diffusion distance was also measured, and the results are as follows: Figure 6 As shown in (c) above. Further, the average diffusion coefficient and the furthest diffusion distance were obtained, as shown in Table 4. It is easy to see that Ni... 2+ The ions exhibit the largest maximum diffusion distance and average diffusion coefficient, but are only 5.89 μm and 2.98 × 10⁻⁶, respectively. -13 cm 2 ·s -1 This once again confirms the conclusion that the ion interdiffusion rate at the interface is extremely low.

[0053] Table 4: Ion diffusion coefficient and diffusion distance at the interface

[0054] Comparative examples and comparative examples show that by adjusting the NiZn-based ferrite formulation and sintering temperature, the sintering temperature of the heterogeneous co-fired composite substrate was reduced from 1150 °C to 1125 °C. A trace amount of Cu... 2+ The replacement significantly improved the shrinkage characteristic curve of NiZn ferrite, with the shrinkage rate changing from 10 × 10⁻⁶. -4 K -1 Upgraded to 12×10 -4 K -1 The densification temperature is advanced to before the YIG ferrite, achieving heterogeneous co-firing bonding with the YIG ferrite. Additionally, Cu... 2+ Trace substitution of ions also increases the saturation magnetization of NiZn ferrite, which contributes to the improvement of the substrate's gyromagnetic properties. The NiZn-YIG ferrite heteroco-fired body exhibits a tight, crack-free interface with clear boundaries and extremely low ion interdiffusion. 2+ The ions exhibit the largest diffusion distance and diffusion coefficient, but only 5.89 μm and 2.98 × 10⁻⁶, respectively. -13 cm 2 ·s -1 It is precisely because of trace amounts of Cu 2+Ion substitution led to an increased yield rate and an earlier densification temperature in the NiZn system, which improved its co-firing compatibility with YIG, ultimately achieving heterogeneous co-firing of NiZn ferrite and YIG ferrite. When Cu... 2+ With ion substitution amounts of 0.1% and 0.2%, co-firing did not cause cracking of the YIG outer ring, indicating that the co-firing compatibility between NiZn ferrite and the YIG outer ring is significantly better than that without Cu. 2+ In the case of ion substitution, this is due to Cu 2+ Optimization of shrinkage rate of NiZn ferrite by ion substitution.

[0055] The above embodiments are merely examples. For instance, the YIG microwave ferrite nested on the outside of the dual ferrite heterogeneous co-fired composite substrate can be hollow ring-shaped or other shapes reported in the prior art (e.g., hollow square shape), as long as the shape and size of the central ferrite and the outer nested ferrite meet the requirements for nesting after co-pressing (that is, the outer diameter of the central ferrite can be less than or equal to the hollow inner diameter of the outer nested ferrite, as long as they can form an integral composite green body after co-pressing).

[0056] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-ferrite heterogeneous co-fired composite substrate, comprising a central ferrite and an outer nested ferrite, characterized in that, The central ferrite is Cu. 2+ Ion-substituted NiZn-based ferrites, wherein the outer nested ferrite is Bi 3+ The ion-substituted YIG-based microwave ferrite, wherein the central ferrite and the outer nested ferrite are co-fired together, and the sintering temperature used for co-firing is 1100 ~ 1150 ℃.

2. The dual ferrite heterogeneous co-fired composite substrate as described in claim 1, characterized in that, The described Cu 2+ ion-substituted NiZn ferrite has a chemical general formula of Ni 1-a-b Zn b Cu a Fe2O4, where 0.00 < a ≤ 0.20 and 0.2 ≤ b ≤ 0.4; preferably, 0.00 < a ≤ 0.05; The Bi 3+ Ion-substituted YIG-based microwave ferrites, with the general chemical formula Yi... 3-c-d Bi d Al c Fe5O 12 , of which 0.0 <c≤ 0.5,0.0<d ≤ 0.5。 3. The dual ferrite heterogeneous co-fired composite substrate as described in claim 1, characterized in that, The outer nested ferrite is a hollow circular ring-shaped ferrite or a hollow square ferrite, nested outside the central ferrite.

4. The method for preparing the dual ferrite heterogeneous co-fired composite substrate according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Using NiO powder, ZnO powder, CuO powder, Fe2O3 powder, Bi2O3 powder, Y2O3 powder, and Al2O3 powder as raw materials, respectively according to the general chemical formula Ni 1-a-b Zn b Cu a Fe2O4 and Y 3-c-d Bi d Al c Fe5O 12 The nominal stoichiometric ratio of the metallic elements in the raw materials is used to mix and form NiZn-based ferrite mixed powder and YIG-based ferrite mixed powder; wherein, 0.00 <a≤ 0.20,0.20 ≤ b ≤ 0.40,0.0<c ≤ 0.5,0.0<d ≤ 0.5; (2) The NiZn-based ferrite mixed powder and the YIG-based ferrite mixed powder are respectively subjected to wet ball milling to obtain NiZn-based ferrite primary ball milling slurry and YIG-based ferrite primary ball milling slurry. (3) The ball mill slurry obtained in step (2) is dried, passed through a 40-80 mesh sieve, and pre-calcined to obtain NiZn-based ferrite pre-calcined powder and YIG-based ferrite pre-calcined powder; wherein, each type of pre-calcined powder is kept at a pre-calcination temperature of 850-950 ℃ for 2-4 h. (4) The pre-calcined powder obtained in step (3) is subjected to wet ball milling to obtain NiZn ferrite secondary ball milling slurry and YIG ferrite secondary ball milling slurry. (5) The secondary ball mill slurry obtained in step (4) is dried, passed through a 40-80 mesh sieve, and granulated by adding a binder to obtain NiZn ferrite granulated powder and YIG ferrite granulated powder. (6) Place the NiZn ferrite granulated powder obtained in step (5) into a mold and press it to obtain a NiZn ferrite cylindrical green body. (7) Using the cylindrical green body obtained in step (6) as the core mold, the YIG ferrite granulated powder obtained in step (5) is placed into the matching external nested mold for pressing and molding to obtain NiZn-YIG ferrite composite green body. (8) The NiZn-YIG ferrite composite green body obtained in step (7) is subjected to debinding treatment; (9) The NiZn-YIG ferrite composite green blank obtained in step (8) is placed in an air atmosphere in a sintering furnace for co-sintering at a sintering temperature of 1100 ~ 1150 ℃, thereby obtaining a dual ferrite heterogeneous co-fired composite substrate.

5. The preparation method according to claim 4, characterized in that, In step (6), the molding pressure used for pressing is 100~150 MPa, and the holding time is 30~60 s; In step (7), the molding pressure used for pressing is 150 ~ 200 MPa, and the holding time is 30 ~ 60 s.

6. The preparation method according to claim 4, characterized in that, In step (8), the glue removal temperature used in the glue removal process is 400 ~ 500 ℃.

7. The preparation method according to claim 4, characterized in that, In step (6), the diameter of the cylindrical green blank is 5.27 mm; In step (7), the outer nested mold is used to form a hollow annular structure with an inner diameter of 5.27 mm and an outer diameter of 11 mm.

8. The application of the dual ferrite heterogeneous co-fired composite substrate as described in any one of claims 1-3 in circulators or isolators.

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