CN113511888B

CN113511888B - Narrow-linewidth LTCF gyromagnetic substrate material and preparation method thereof

Info

Publication number: CN113511888B
Application number: CN202110372118.7A
Authority: CN
Inventors: 贾利军; 沈阳; 邱华; 许伦; 张怀武
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2021-04-07
Filing date: 2021-04-07
Publication date: 2022-05-03
Anticipated expiration: 2041-04-07
Also published as: CN113511888A

Abstract

A narrow-linewidth LTCF gyromagnetic substrate material and a preparation method thereof belong to the technical field of electronic ceramics. The gyromagnetic substrate material comprises a main material and an auxiliary material, wherein the structural formula of the main material is as follows: li_{0.65‑0.5x‑0.5y}Zn_xTi_0.3‑yFe_{2.05‑0.5x+1.5y‑z}O₄Wherein x is more than or equal to 0.35 and less than or equal to 0.4, y is more than or equal to 0 and less than or equal to 0.12, and z is more than or equal to 0 and less than or equal to 0.12; relative to the main material, the content of the auxiliary material is as follows: 0 to 0.2 wt% of BZB glass, 0.3 to 0.4 wt% of Bi₂O₃. The narrow-linewidth LTCF gyromagnetic substrate material prepared by the invention has a low sintering temperature and also has good gyromagnetic characteristics: narrow ferromagnetic resonance linewidth: (<100Oe), low coercivity: (<1.2Oe), low microwave dielectric loss: (<1×10^‑3) And higher saturation magnetization: (>3200Oe)。

Description

Narrow-linewidth LTCF gyromagnetic substrate material and preparation method thereof

Technical Field

The invention belongs to the technical field of electronic ceramics, and particularly relates to an LTCF gyromagnetic substrate material with narrow ferromagnetic resonance line width, low coercive force, low dielectric loss and high saturation magnetization and a preparation method thereof.

Background

Because the LiZn ferrite has the characteristics of wide saturation magnetization adjustable range, low coercive force, low microwave loss, good temperature stability, low cost and the like at room temperature, the LiZn ferrite is widely applied to substrate materials of microwave locking phase shifters and high-power devices. With the development of electronic information systems towards miniaturization, integration and high frequency, the volume of the microwave device becomes a key factor restricting the development of the microwave device. The advent of low temperature co-fired ferrite (LTCF) technology has provided an effective solution for the miniaturization of microwave ferrite devices. However, to achieve high densification and low ferromagnetic resonance linewidths, LiZn ferrite typically requires sintering at high temperatures around 1100 ℃ which is much higher than the process requirements of LTCF technology (< 920 ℃). Therefore, it is an urgent problem to realize a low-temperature sintering process compatible with LTCF technology and to improve the gyromagnetic properties of low-temperature sintered LiZn ferrite, especially to narrow the ferromagnetic resonance line width.

Currently, research around low-temperature sintering and gyromagnetic property optimization of LiZn-based ferrite materials is mainly focused on low-melting point oxides and glass doping modification. The invention patent with the application number of 201110001941.3 discloses a LiZn ferrite material for a Ka-band phase shifterIn a lithium-rich manner with the addition of Bi₂O₃、NiO、V₂O₅Oxygen introduction sintering of the sintering aid is carried out, and the obtained sample has high saturation magnetization (4800 kA/m), low ferromagnetic resonance line width (12kA/m) and low coercive force (<120A/m), however, are difficult to be compatible with LTCF technology due to the tendency of oxidation of the electrode material caused by the sintering process using an oxygen atmosphere at-1000 c. The invention patent with the application number of 201410705259.6 discloses a preparation method of a low-coercivity LiZnTi gyromagnetic ferrite material, which adds ZBSL glass and nano Al into the gyromagnetic ferrite₂O₃And the sintering aid reduces the sintering temperature to 900-940 ℃, so that the saturation magnetic induction density of the sample is 260-330 mT, the coercive force of the sample is 150-380A/m, the coercive force of the sample prepared by the method is still high, and the dielectric loss and the ferromagnetic resonance line width are not reported. "F Xie, L Jia, Y ZHao, et al, Low-temperature characteristics and magnetic characteristics of LiZnTiMn crystals with Bi₂O₃-CuO eutectic mixture[J]Journal of Alloys and Compounds,2017,695:3233-₂O₃And 0.29 wt.% of CuO, wherein the sample sintered at 900 ℃ has the saturation magnetic induction intensity of 324mT and the sintered density of 4.66g/cm³The ferromagnetic resonance line width is 155Oe, the coercive force is 379A/m, and the coercive force and the ferromagnetic resonance line width of the sample prepared by the method are still high. In summary, the requirements of small-scale integration and high-performance application of microwave ferrite devices are met, and a better solution is urgently needed for improving the comprehensive performance indexes (narrow ferromagnetic resonance line width, low coercive force, low microwave dielectric loss, high saturation magnetization and the like) of the LTCF gyromagnetic substrate.

Disclosure of Invention

The invention aims to provide a narrow-linewidth LTCF gyromagnetic substrate material and a preparation method thereof, aiming at the defects of wider ferromagnetic resonance linewidth, larger microwave dielectric loss, higher coercive force, lower sample density and saturation magnetization and the like of the conventional low-temperature sintered LiZn gyromagnetic substrate material.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

narrow linewidth LTCFThe gyromagnetic substrate is made of heavily doped Zn²⁺The iron-deficiency formula of the ions is used for weakening the exchange effect between an oxygen tetrahedral position (A position) and an octahedral position (B position), so that the magnetocrystalline anisotropy broadening is greatly reduced; secondly, adopting oxygen atmosphere for preburning to inhibit Fe in the material²⁺The occurrence of ions further reduces the dielectric loss of microwaves; introduction of Bi₂O₃-ZnO-B₂O₃(BZB) glass and Bi₂O₃The flux system is combined, so that the uniform growth and densification of ferrite grains are realized, the dielectric loss is reduced while the widening of air holes is reduced, and the increase of saturation magnetization is facilitated. The gyromagnetic substrate material is characterized by comprising main materials and auxiliary materials, wherein the structural formula of the main materials is as follows: li_{0.65-0.5x-0.5y}Zn_xTi_0.3-yFe_{2.05-0.5x+1.5y-z}O₄Wherein x is more than or equal to 0.35 and less than or equal to 0.4, y is more than or equal to 0 and less than or equal to 0.12, and z is more than or equal to 0 and less than or equal to 0.12;

the auxiliary materials comprise BZB glass and Bi₂O₃The powder material comprises the following auxiliary materials in percentage by weight relative to the main material: 0 to 0.2 weight percent of BZB glass and 0.3 to 0.4 weight percent of Bi₂O₃。

A preparation method of a narrow-linewidth LTCF gyromagnetic substrate material is characterized by comprising the following steps:

step 1, pre-sintering material preparation:

1.1 to analytically pure iron oxide (Fe)₂O₃) Lithium carbonate (Li)₂CO₃) Zinc oxide (ZnO) and titanium dioxide (TiO)₂) As a raw material, according to the chemical formula: li_{0.65-0.5x-0.5y}Zn_xTi_0.3-yFe_{2.05-0.5x+1.5y-z}O₄Weighing raw materials according to the proportion that x is more than or equal to 0.35 and less than or equal to 0.4, y is more than or equal to 0 and less than or equal to 0.12, and z is more than or equal to 0 and less than or equal to 0.12, weighing the raw materials after calculating the mass of each raw material according to the proportion, and then putting the weighed powder into a planetary ball mill for primary ball milling for 5-6 hours;

1.2 drying and sieving the primary ball-milled material obtained in the step 1.1, putting the material into an alumina crucible, presintering the material for 2-3 hours at 800-850 ℃ in an oxygen atmosphere, cooling the material to room temperature along with a furnace, and taking the material out to obtain a LiZnTi ferrite presintering material;

step 2, adding BZB-Bi₂O₃Carrying out secondary ball milling on the sintering aid:

sieving the LiZnTi ferrite pre-sintering material obtained in the step 1, and adding Bi with the mass equivalent to 0.3-0.4 wt.% of the pre-sintering material₂O₃And 0-0.2 wt% of BZB glass, then carrying out secondary ball milling in a planetary ball mill for 8-12 h, taking the materials after the ball milling is finished, and drying to obtain a LiZnTi ferrite secondary grinding material;

step 3, forming and sintering:

3.1, sieving the secondary grinding materials obtained in the step 2, adding a polyvinyl alcohol (PVA) aqueous solution with the mass being 10-12 wt.% of that of the powder, granulating, and pressing by using a hydraulic machine under the pressure of 8-9 Mpa to prepare an annular biscuit sample;

and 3.2, putting the sample obtained in the step 3.1 into a sintering furnace, heating to 900-920 ℃ at the speed of 2 ℃/min, preserving heat for 2-3 h, and naturally cooling to room temperature along with the furnace after sintering is completed to obtain the narrow-linewidth LTCF gyromagnetic substrate material.

Further, in step 1.2, the partial pressure of oxygen is 0.3-0.4 MPa, and the flow rate is 200-300 mL/min.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention adopts the cooperative regulation and control of Li⁺、Zn²⁺、Ti⁴⁺、Fe³⁺The occupation of ions in the ferrite lattice changes the A, B-bit magnetic moment and the A, B-bit exchange effect, so that the effect of remarkably reducing the ferromagnetic resonance line width and simultaneously obtaining low coercive force and higher saturation magnetization is achieved. Further, on the basis of an iron-deficiency formula, Fe is inhibited through oxygen atmosphere pre-burning treatment²⁺The generation of ions, and thus the microwave dielectric loss of the material, is optimized.

2. The invention introduces BZB glass with low melting point and Bi on the basis of optimizing the crystal structure of the gyromagnetic ferrite material₂O₃A gradient fluxing system is formed, and the grain growth and densification processes are finely regulated, so that the microstructure of the material is improved, the saturation magnetization and dielectric loss of the material are further improved, and the coercive force is reduced.

3. The narrow-linewidth LTCF gyromagnetic substrate material prepared by the invention has low sintering temperature (900 ℃) and good gyromagnetic property: narrow ferromagnetic resonance linewidth: (<100Oe), low coercivity: (<1.2Oe), low microwave dielectric loss: (<1×10^-3) And higher saturation magnetization: (>3200 Oe). The prepared gyromagnetic substrate material not only meets the requirements of the LTCF process, but also has excellent gyromagnetic performance of a key substrate material required by a microwave ferrite device.

Drawings

FIG. 1 is an SEM image of ferrite samples obtained in comparative example (a), example 2(b) and example 3 (c).

Detailed Description

The technical scheme of the invention is detailed in the following by combining the drawings and the embodiment.

Narrow-linewidth LTCF gyromagnetic substrate material for cooperatively regulating and controlling Li⁺、Zn²⁺、Ti⁴⁺、Fe³⁺BZB-Bi is introduced on the basis of occupying distribution of ions in ferrite crystal lattice₂O₃The gradient flux system obtains a compact polycrystalline structure, so that the obtained LiZnTi gyromagnetic ferrite material has narrow ferromagnetic resonance line width, low coercive force, low microwave dielectric loss and high saturation magnetization.

Example 1

A preparation method of a narrow-linewidth LTCF gyromagnetic substrate material comprises the following specific steps:

step 1, pre-sintering material preparation:

1.1 to analytically pure iron oxide (Fe)₂O₃) Lithium carbonate (Li)₂CO₃) Zinc oxide (ZnO) and titanium dioxide (TiO)₂) As a raw material, according to the chemical formula: li_{0.65-0.5x-0.5y}Zn_xTi_0.3-yFe_{2.05-0.5x+1.5y-z}O₄(x is 0.4, y is 0, and z is 0.06), weighing the raw materials after calculating the mass of each raw material, and then putting the weighed powder into a planetary ball mill for primary ball milling for 6 hours;

1.2 drying and sieving the primary ball-milled material obtained in the step 1.1, putting the material into an alumina crucible, presintering the material for 2 hours at 800 ℃ in an oxygen atmosphere (oxygen partial pressure of 0.3Mpa and flow rate of 200mL/min), cooling the material to room temperature along with a furnace, and taking the material out to obtain a LiZnTi ferrite presintering material;

sieving the LiZnTi ferrite pre-sintering material obtained in the step 1, and adding BZB glass which is equivalent to k wt.% of the pre-sintering material and t wt.% of Bi₂O₃(k is 0, t is 0.4), then carrying out secondary ball milling in a planetary ball mill for 12h, taking materials after the ball milling is finished, and drying to obtain a LiZnTi ferrite secondary grinding material;

step 3, molding and sintering:

3.1 sieving the secondary grinding materials obtained in the step 2, adding a polyvinyl alcohol (PVA) aqueous solution with the mass equivalent to 10 wt.% of the powder for granulation, and pressing the mixture into an annular biscuit sample by using a hydraulic machine under the pressure of 9 Mpa;

and 3.2, putting the sample obtained in the step 3.1 into a sintering furnace, heating to 920 ℃ at the speed of 2 ℃/min, preserving heat for 2 hours, and naturally cooling to room temperature along with the furnace after sintering is finished to obtain the narrow-linewidth LTCF gyromagnetic substrate material.

The narrow linewidth LTCF gyromagnetic substrate material prepared in the embodiment 1 has the following properties: ferromagnetic resonance line width Δ H @9.3GHz 91 Oe; coercive force H_c0.91 Oe; saturation magnetization of 4 pi M_s3203 Oe; dielectric loss tangent tan delta_ε@9.3GHz 7.20×10^-4(ii) a Sample density ρ 4.65g/cm³。

Example 2

This example is different from example 1 in that: step 1.1, wherein y is 0.06; in the step 2, k is 0.09, and t is 0.3; the sintering temperature in step 3.2 was 900 ℃ and the rest of the procedure was the same as in example 1.

The narrow linewidth LTCF gyromagnetic substrate material prepared in the embodiment 2 has the following properties: ferromagnetic resonance line width Δ H @9.3GHz 99 Oe; coercive force H_c1.15 Oe; saturation magnetization of 4 pi M_s3872 Oe; dielectric loss tangent tan delta_ε@9.3GHz 6.53×10^-4(ii) a Sample density ρ 4.70g/cm³。

Example 3

This example is different from example 1 in that: step 1.1, wherein y is 0.06; in the step 2, k is 0.12, and t is 0.3; the sintering temperature in step 3.2 was 900 ℃ and the rest of the procedure was the same as in example 1.

The narrow linewidth LTCF gyromagnetic substrate material prepared in the embodiment 3 has the following properties: ferromagnetic resonance line width Δ H @9.3GHz 94 Oe; coercive force H_c1.13 Oe; saturation magnetization of 4 pi M_s3918 Oe; dielectric loss tangent tan delta_ε@9.3GHz 5.32×10^-4(ii) a Sample density ρ 4.72g/cm³。

Comparative example

The comparative example is different from example 1 in that: step 1.1 the same procedure as in example 1 was followed, wherein x is 0, y is 0, and z is 0.

The performance of the gyromagnetic ferrite material prepared by the comparative example is as follows: ferromagnetic resonance linewidth Δ H @9.3GHz451 Oe; coercive force H_c3.15 Oe; saturation magnetization of 4 pi M_s2194 Oe; dielectric loss tangent tan delta_ε@9.3GHz>100×10^-4(ii) a Sample density ρ 4.46g/cm³。

FIG. 1(a), FIG. 1(b) and FIG. 1(c) are the micrographs of comparative example, example 2 and example 3, respectively, from which it can be seen that BZB-Bi is introduced₂O₃The fluxing system is beneficial to obtaining a uniform and compact microstructure. Table 1 shows the performance parameters of the comparative examples and examples. By heavily doping Zn²⁺Ions, weakening magnetocrystalline anisotropy, greatly reducing ferromagnetic resonance line width of the material, and simultaneously modulating Li by cooperation⁺、Ti⁴⁺、Fe³⁺The occupied distribution of plasma metal ions in the ferrite crystal lattice changes the magnetic moment of molecules, thereby improving the saturation magnetization. BZB glass and Bi₂O₃The combined doping has obvious effect on improving the density of the material, and is beneficial to increasing the saturation magnetization and reducing the microwave dielectric loss.

TABLE 1 Performance parameters of comparative examples and examples

Claims

1. The narrow-linewidth LTCF gyromagnetic substrate material is characterized by comprising main materials and auxiliary materials, wherein the main materials have the structural formula: li_{0.65-0.5x-0.5y}Zn_xTi_0.3-yFe_{2.05-0.5x+1.5y-z}O₄Wherein x is more than or equal to 0.35 and less than or equal to 0.4, y is more than or equal to 0 and less than or equal to 0.12, and z is more than or equal to 0 and less than or equal to 0.12;

relative to the main material, the contents of the auxiliary materials are as follows: 0.09 to 0.2 weight percent of BZB glass and 0.3 to 0.4 weight percent of Bi₂O₃。

2. A preparation method of a narrow-linewidth LTCF gyromagnetic substrate material is characterized by comprising the following steps:

step 1, pre-sintering material preparation:

1.1 using iron oxide, lithium carbonate, zinc oxide and titanium dioxide as raw materials according to a chemical formula: li_0.65-0.5x- _0.5yZn_xTi_0.3-yFe_{2.05-0.5x+1.5y-z}O₄X is more than or equal to 0.35 and less than or equal to 0.4, y is more than or equal to 0 and less than or equal to 0.12, and z is more than or equal to 0 and less than or equal to 0.12, and then the weighed powder is subjected to primary ball milling;

1.2 drying and screening the primary ball-milled material obtained in the step 1.1, presintering the material at 800-850 ℃ for 2-3 h in an oxygen atmosphere, cooling the material to room temperature along with a furnace, and taking out the material to obtain a LiZnTi ferrite presintering material;

step 2, secondary ball milling:

sieving the LiZnTi ferrite pre-sintering material obtained in the step 1, and adding Bi with the mass equivalent to 0.3-0.4 wt.% of the pre-sintering material₂O₃And BZB glass accounting for 0.09-0.2 wt% of the raw materials, performing secondary ball milling, taking the materials after the ball milling is finished, and drying to obtain a LiZnTi ferrite secondary grinding material;

step 3, forming and sintering:

3.1, sieving the secondary grinding materials obtained in the step 2, adding polyvinyl alcohol with the mass being 10-12 wt.% of that of the powder materials for granulation, and then pressing and forming by using a hydraulic machine under the pressure of 8-9 Mpa;

3.2, putting the sample obtained in the step 3.1 into a sintering furnace, heating to 900-920 ℃, preserving heat for 2-3 hours, and naturally cooling to room temperature along with the furnace after sintering is completed to obtain the narrow-linewidth LTCF gyromagnetic substrate material.

3. The method for preparing the narrow-linewidth LTCF gyromagnetic substrate material according to claim 2, wherein in the step 1.2, the partial pressure of oxygen is 0.3-0.4 MPa, and the flow rate is 200-300 mL/min.