阅读说明：本技术 一种Li系尖晶石微波铁氧体材料及其制备方法 (Li-series spinel microwave ferrite material and preparation method thereof ) 是由 曹迪 袁礼新 张立春 杜兆富 闫旭 于 2021-06-23 设计创作，主要内容包括：本发明公开一种Li系尖晶石微波铁氧体材料及其制备方法。本发明首先公开了一种Li系尖晶石微波铁氧体材料,所述Li系尖晶石微波铁氧体材料化学分子式为Li-((0.5-0.5a-0.5b))Zn-(a)Cu-(b)Mn-(0.02)Fe-((2.48-0.5a-0.5b))O-(4),其中0.20＜a＜0.30,0.01≤b＜0.03,本发明还提供了一种制备上述铁氧体材料的方法。本发明所得材料具有高饱和磁化强度、低介电损耗和低铁磁共振线宽的优点。另外,在本发明方法中引入助溶剂和低熔点氧化物玻璃相助烧剂后,有助于降低制备铁氧体材料过程中的烧结温度,将该铁氧体材料应用于环行器、隔离器或移相器等铁氧体微波器件中,该器件具有低插损、高隔离等优点,具有很好的应用前景。(The invention discloses a Li-series spinel microwave ferrite material and a preparation method thereof. The invention firstly discloses a Li-series spinel microwave ferrite material, and the chemical molecular formula of the Li-series spinel microwave ferrite material is Li (0.5‑0.5a‑0.5b) Zn a Cu b Mn 0.02 Fe (2.48‑0.5a‑0.5b) O 4 Wherein a is more than 0.20 and less than 0.30, and b is more than or equal to 0.01 and less than 0.03, and the invention also provides a method for preparing the ferrite material.The material obtained by the invention has the advantages of high saturation magnetization, low dielectric loss and low ferromagnetic resonance line width. In addition, after the cosolvent and the low-melting-point oxide glass phase sintering aid are introduced in the method, the sintering temperature in the process of preparing the ferrite material is favorably reduced, and the ferrite material is applied to ferrite microwave devices such as a circulator, an isolator or a phase shifter and the like, so that the device has the advantages of low insertion loss, high isolation and the like and has good application prospect.)

1. The Li-series spinel microwave ferrite material is characterized in that the chemical molecular formula of the Li-series spinel microwave ferrite material is Li_{(0.5-0.5a-0.5b)}Zn_aCu_bMn_0.02Fe_{(2.48-0.5a-0.5b)}O₄Wherein a is more than 0.20 and less than 0.30, and b is more than or equal to 0.01 and less than 0.03.

2. The Li-based spinel microwave ferrite material of claim 1, wherein the chemical formula of the Li-based spinel microwave ferrite material is Li_0.36Zn_0.26Cu_0.02Mn_0.02Fe_2.34O₄，Li_0.365Zn_0.26Cu_0.01Mn_0.02Fe_{2.34 5}O₄Or Li_0.37Zn_0.24Cu_0.02Mn_0.02Fe_2.35O₄。

3. The method for preparing a Li-spinel microwave ferrite material according to claim 1 or 2, comprising the steps of:

(1) with Li₂CO₃，ZnO，CuCO₃Cu(OH)₂·xH₂O，MnCO₃，Fe₂O₃Is an initialRaw materials, calculating and weighing each raw material according to the chemical molecular formula of the ferrite material, mixing, adding a fluxing agent, performing ball milling or sanding, and drying to obtain primary mixed powder;

(2) pre-burning the primary mixed powder, and keeping the temperature to obtain a pre-burned material;

(3) adding a low-melting-point oxide glass phase sintering aid into the pre-sintering material, carrying out ball milling or sand milling, and drying to obtain secondary mixed powder;

(4) adding a solvent, a dispersing agent, an adhesive and a plasticizer into the secondary mixed powder, and carrying out ball milling for 24-48h to obtain casting slurry;

(5) sieving the casting slurry, defoaming and casting to obtain a ferrite green tape;

(6) and laminating, slitting and sintering the ferrite green porcelain tape to obtain the low-temperature sintered Li-series spinel microwave ferrite material.

4. The method of claim 3, wherein the low-melting-point oxide glass phase sintering aid comprises SiO_2-B₂O₃CaO-M glasses, where M comprises MgO, Al₂O₃、PbO、BaO、Bi₂O₃、ZnO、Na₂O、K₂One or more of O; preferably, the flux comprises Bi₂O₃。

5. The method of claim 4, wherein the SiO is_2-B₂O₃The addition amount of the CaO-M glass is 3.0 to 5.0 wt% of the initial raw material pre-sintering material; preferably, the amount of the flux added is 0.2 to 1.0 wt% of the total mass of the starting materials.

6. The method of claim 4, wherein the SiO is_2-B₂O₃in-CaO-M glasses, SiO₂In an amount of 40-60 wt%, B₂O₃The content of (B) is 8-30 wt%, the content of CaO is 2-25 wt%, and the content of M is 5-30 wt%.

7. The method of claim 3, wherein the solvent comprises one or more of ethanol, n-butanol, acetone, butanone, xylene; preferably, the dispersant comprises one or more of triolein, triethanolamine, tributyl phosphate, triethyl phosphate; preferably, the binder comprises one or more of polyvinyl butyral, ethyl cellulose; preferably, the plasticizer comprises one or more of dibutyl phthalate, dioctyl phthalate and polyvinyl alcohol.

8. The preparation method according to claim 3, wherein the pre-sintering temperature is 820-880 ℃, and the heat preservation time is 2-4 h; preferably, the grain diameter D50 of the secondary mixed powder is 2.0-3.0 microns; preferably, the viscosity of the casting slurry is 500-1500 mPas.

9. The method as claimed in claim 3, wherein the sintering temperature is 850-920 ℃ and the sintering time is 15-60 min.

10. A ferrite microwave device comprising the Li-based spinel microwave ferrite material according to claim 1 or 2; preferably, the ferrite microwave device comprises a circulator, an isolator or a phase shifter.

Technical Field

The invention relates to the field of microwave ferrite materials. More particularly, relates to a Li-series spinel microwave ferrite material and a preparation method thereof.

Background

With the development of radar technology and the demand of application fields, microwave/millimeter wave devices such as phase shifters for phased array radar are developing towards high power, high precision and high frequency. The Li-series microwave ferrite has the advantages of high saturation magnetization, good process stability, low manufacturing cost and the like, and can be well applied to ferrite microwave devices in Ka wave bands and frequency bands above the Ka wave bands. However, a large number of air holes exist in the microstructure, so that the high-strength ferrite substrate is difficult to prepare, and the application of the ferrite substrate in a microstrip circulator and an isolator is limited. Along with the development of miniaturization of an active phased array transceiver module (T/R module), the circulator/isolator has higher and higher requirements on miniaturization and integration, a raw porcelain band with accurate thickness and compactness is manufactured by sintering ferrite powder at low temperature, and required circuit patterns are manufactured on the raw porcelain band by processes of laser drilling, precise conductor paste printing and the like, so that the integrated manufacturing of the circulator/isolator can be realized.

However, in the conventional method, the sintering temperature of the Li-based ferrite is about 1000 ℃, which can meet the application requirements, but when the sintering temperature is too low, the single-phase ferrite is difficult to form, the porosity is high, the electromagnetic properties such as high saturation magnetization, low ferromagnetic resonance line width, low dielectric loss and the like cannot be simultaneously met, and the requirements of the circulator/isolator on low insertion loss and high isolation cannot be met, which becomes an important problem to be solved in the field. The development of low-temperature sintered spinel type microwave ferrite material and raw belt casting process is required, the sintering temperature is less than 920 ℃, and the microwave ferrite has the characteristics of high saturation magnetization and low dielectric loss.

In order to solve the problems, a Li-based spinel microwave ferrite material with excellent performance and low sintering temperature is developed, and the method has important significance for the application of the Li-based ferrite material in the aspect of microwave ferrite devices.

Disclosure of Invention

The first purpose of the invention is to provide a Li-series spinel microwave ferrite material which has the advantages of high saturation magnetization, low ferromagnetic resonance line width, low sintering temperature, low dielectric loss and the like.

The second purpose of the invention is to provide a preparation method of the Li-based spinel microwave ferrite material.

The third purpose of the invention is to provide a ferrite microwave device, which comprises the Li-series spinel microwave ferrite material, and realizes the manufacture of an integrated circulator/isolator by combining the low-temperature co-fired ceramic screen printing and the low-temperature co-fired process, and the ferrite microwave device has the advantages of low insertion loss, high isolation and the like.

In order to achieve the first object, the present invention provides a Li-based spinel microwave ferrite material, wherein the chemical formula of the Li-based spinel microwave ferrite material is Li_{(0.5-0.5a-0.5b)}Zn_aCu_bMn_0.02Fe_{(2.48-0.5a-0.5b)}O₄Wherein a is more than 0.20 and less than 0.30, and b is more than or equal to 0.01 and less than 0.03.

In the technical scheme of the invention, proper Zn, Cu and Mn ions are selected for substitution and Bi are selected according to the ion occupying characteristics in the Li-series spinel ferrite₂O₃The sintering temperature is reduced; in addition, low melting point oxide glass SiO is added₂-B₂O₃CaO-M, with a softening temperature of 570-610 ℃, can further promote the sintering process of the material and reduce the sintering temperature.

Preferably, the chemical formula of the Li-based spinel microwave ferrite material is Li_0.36Zn_0.26Cu_0.02Mn_0.02Fe_2.34O₄，Li_0.365Zn_0.26Cu_0.01Mn_0.02Fe_2.345O₄Or Li_0.37Zn_0.24Cu_0.02Mn_0.02Fe_2.35O₄。

In the technical scheme of the invention, the Li-based spinel microwave ferrite materials are all at the sintering temperatureObtained at a temperature of less than or equal to 920 ℃, and has the advantages of high saturation magnetization, low ferromagnetic resonance line width, low sintering temperature, low dielectric loss and the like by substituting Zn and a small amount of Cu and Mn ions according to the ion occupying characteristics of the Li-series spinel ferrite. However, since the sintering temperature of the pure ferrite material is difficult to be lowered to 950 ℃ or lower due to the characteristics of the Li-based spinel ferrite itself, Bi added before the pre-sintering is added₂O₃And the sintering temperature of the material is further reduced under the combined action of the low-melting-point glass added after pre-sintering.

The invention realizes the combination of the electromagnetic property and the low-temperature sintering of the Li-series ferrite by the synergistic action of ion substitution and doping and the sintering assistance of bismuth oxide and low-melting glass.

In order to achieve the second object, the invention also provides a preparation method of the Li-based spinel microwave ferrite material, which comprises the following preparation steps:

(1) with Li₂CO₃，ZnO，CuCO₃Cu(OH)₂·xH₂O，MnCO₃，Fe₂O₃The preparation method comprises the following steps of (1) calculating and weighing raw materials according to the chemical molecular formula of ferrite as initial raw materials, mixing the raw materials, adding a fluxing agent, carrying out ball milling or sanding, and drying to obtain primary mixed powder;

(2) presintering the primary mixed powder, and keeping the temperature to obtain a presintering material;

(3) adding a low-melting-point oxide glass phase sintering aid into the pre-sintering material, and carrying out ball milling or sand milling and drying to obtain secondary mixed powder;

(4) adding the secondary mixed powder into a solvent, a dispersing agent, an adhesive and a plasticizer according to a ratio, and carrying out ball milling for 24-48h to obtain casting slurry;

(5) screening the casting slurry, defoaming and casting to obtain a ferrite green tape;

(6) and laminating, slitting and sintering the ferrite green ceramic tape to obtain the Li-series spinel microwave ferrite material.

Preferably, the low melting point oxide vitreous phase sintering aid comprises SiO_2-B₂O₃CaO-M glass, prepared by high-temperature melting and chemically reacted to form a single glassA glassy phase.

Preferably, M comprises MgO, Al₂O₃、PbO、BaO、Bi₂O₃、ZnO、Na₂O、K₂One or more of O.

Preferably, the flux comprises Bi₂O₃。

Preferably, the SiO_2-B₂O₃The amount of CaO-M glass added is between 3.0 and 5.0% by weight of the initial raw material pre-sinter.

Preferably, the amount of the flux added is 0.2 to 1.0 wt% of the total mass of the starting materials.

Preferably, the SiO_2-B₂O₃in-CaO-M glasses, SiO₂In an amount of 40-60 wt%, B₂O₃The content of (A) is 8-30 wt%, the content of CaO is 2-25 wt%, and the content of M is 5-30 wt% to ensure SiO_2-B₂O₃CaO-M can form a single glass phase, in which SiO₂、B₂O₃CaO forms a main network structure of single glass, and the addition of M adjusts the fining temperature, softening temperature and wettability with Li-based ferrite of the glass.

Wherein the addition of M can adjust the softening point and clarification temperature of oxide glass, simultaneously increase the wettability between glass powder and Li-series ferrite, promote ion diffusion in the low-temperature sintering process, reduce the sintering activation energy of the ferrite, and when the glass component contains MgO and Al₂O₃Or ZnO, which is favorable for improving the wettability of the glass and the Li-series ferrite powder, when the glass component contains PbO, BaO and Bi₂O₃Or ZnO, which can be beneficial to regulating the softening point of the glass when the glass component contains Na₂O or K₂O, which is advantageous in lowering the fining temperature of the glass, is superior to the effect of containing M alone in its synergistic effect when the glass component contains M with different effects as described above.

The application also provides a SiO₂-B₂O₃-a method for producing a CaO-M glass comprising the steps of:

step 1, taking an oxide or carbonate of a target product as an initial raw material, and batching according to a mass ratio;

step 2, putting the mixed powder obtained in the step 1 into a corundum crucible or a platinum crucible, melting for 1 hour at the temperature of 1400 ℃ and 1550 ℃, and quenching into deionized water to obtain glass broken slag;

step 3, ball-milling the glass broken slag obtained in the step 2, controlling the particle size D50 of the powder to be 1.0-3.0 microns to ensure good dispersibility of the casting slurry, and then drying to obtain SiO₂-B₂O₃CaO-M glass.

Preferably, the solvent includes, but is not limited to, one or more of ethanol, n-butanol, acetone, butanone, xylene.

According to a specific embodiment of the present invention, the solvent adopted in the present invention may be a mixed solvent, specifically, the mass ratio of ethanol to acetone is 3: 2, the solvent accounts for 50-100% of the mass of the powder.

Preferably, the dispersing agent comprises one or more of glycerol trioleate, triethanolamine, tributyl phosphate and triethyl phosphate, and accounts for 1-3% of the mass of the powder.

According to a particular embodiment of the invention, the dispersant is tributyl phosphate.

Preferably, the adhesive comprises one or more of polyvinyl butyral and ethyl cellulose, and accounts for 10-20% of the mass of the powder.

According to a particular embodiment of the invention, the binder is polyvinyl butyral.

Preferably, the plasticizer comprises one or more of dibutyl phthalate, dioctyl phthalate and polyvinyl alcohol, and accounts for 5-10% of the mass of the powder.

According to a particular embodiment of the invention, the plasticizer is dibutyl phthalate.

Preferably, the pre-sintering temperature is 820-880 ℃, and the heat preservation time is 2-4 h.

Preferably, the grain diameter D50 of the secondary mixed powder is 2.0-3.0 microns.

In the scheme of the invention, the average grain diameter D50 of the secondary mixed powder is controlled to be 2.0-3.0 microns, and a large number of experiments prove that the average grain diameter D50 provided by the invention is beneficial to preparing the low-temperature sintered Li-series spinel microwave ferrite material.

Preferably, the viscosity of the casting slurry is 500-1500mPa & s, so as to ensure that the slurry has good leveling property in the casting process.

Preferably, the sintering temperature is 850-920 ℃, and the sintering time is 15-60 min.

To achieve the third object, the present invention also provides a ferrite microwave device comprising the above Li-based spinel microwave ferrite material.

Preferably, the ferrite microwave device includes, but is not limited to, a circulator, an isolator or a phase shifter.

Unless otherwise indicated, all starting materials for the present invention are commercially available and any ranges recited herein include any endpoints and any numbers between the endpoints and any subranges between the endpoints or any numbers between the endpoints.

The invention has the following beneficial effects:

the invention adjusts the content of the cosolvent, the type and the content of the glass phase sintering aid and the particle size of the powder in the preparation of the Li-series spinel microwave ferrite material, so that the Li-series spinel microwave ferrite material has high saturation magnetization (more than or equal to 4550Gs), low ferromagnetic resonance line width (delta H less than or equal to 400Oe) and low dielectric loss (tan delta less than or equal to 1.5 multiplied by 10)^-3) Low-temperature sintering (less than or equal to 920 ℃), and the like.

The preparation method of the low-temperature sintered Li-series spinel microwave ferrite material has simple process and low sintering temperature, and the low-temperature sintered Li-series spinel microwave ferrite material is applied to ferrite microwave devices such as circulators, isolators or phase shifters, and has the advantages of low insertion loss, high isolation and the like and good application prospect.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 shows a physical representation of a low temperature sintered microwave ferrite cast green tape prepared in example 1.

FIG. 2 shows the DSC chart of the prepared low melting point oxide glass.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

Example 1

Provides a compound of the formula Li_0.36Zn_0.26Cu_0.02Mn_0.02Fe_2.34O₄The Li spinel microwave ferrite and the preparation method thereof. The specific manufacturing steps are as follows:

(1) with Li₂CO₃，ZnO，CuCO₃Cu(OH)₂·xH₂O，MnCO₃，Fe₂O₃Taking the raw materials as initial raw materials, calculating and weighing the raw materials according to the chemical molecular formula of ferrite, mixing, adding 1.0 wt% of Bi₂O₃Ball-milling the powder for 20h, and then drying for 5h to obtain primary mixed powder.

(2) And putting the primary mixed powder into a corundum crucible, presintering at 850 ℃, preserving heat for 4 hours, and cooling along with a furnace to obtain a presintering material.

(3) Adding the pre-sintering material into 5.0 wt% of SiO₂-B₂O₃CaO-M glass, in which the glass component is SiO₂54 wt% of B₂O₃The content of the CaO accounts for 18 weight percent, the content of the CaO accounts for 10 weight percent, and M is MgO, PbO or Na₂O、K₂And (3) performing ball milling on the mixture of O with the content of 18 wt% for 24h, and drying for 5h to obtain secondary mixed powder.

(4) Mixing ethanol and acetone according to a mass ratio of 3: 2, mixing the mixed solvent, powder, tributyl phosphate, polyvinyl butyral and dibutyl phthalate according to a mass ratio of 1: 1: 0.095: 0.762: 1.905, and preparing casting slurry by ball milling for 48 hours.

(5) And (3) passing the casting slurry through a 120-mesh screen, defoaming, controlling the viscosity to be 1000mPa & s, and casting to obtain the ferrite green tape.

(6) Laminating and cutting the ferrite green porcelain tape, and sintering at 915 ℃ for 40min to finally obtain Li_0.36Zn_0.26Cu_0.02Mn_0.02Fe_2.34O₄A microwave ferrite material.

The glass powder has a DSC curve shown in FIG. 2, and has a softening temperature of 583.87 deg.C and a low softening point, which can promote sintering of the material. The material has a saturation magnetization of 4580Gs and a dielectric loss tangent less than or equal to 1.48 multiplied by 10^-3The ferromagnetic resonance line width Δ H is 367 Oe.

Example 2

Provides a compound of the formula Li_0.365Zn_0.26Cu_0.01Mn_0.02Fe_2.345O₄The Li spinel microwave ferrite and the preparation method thereof. Referring to the preparation steps of example 1, only the kinds and the proportions of the glass components, specifically SiO, were adjusted₂56 wt% of B₂O₃The content of the CaO is 18 weight percent, the content of the CaO is 8 weight percent, and M is MgO, BaO or Na₂O、K₂The content of the mixture of O is 18 wt%, the sintering temperature is changed to 920 ℃, the sintering time is 40min, and other technological parameters are not changed.

The glass powder has a DSC curve shown in FIG. 2, and has a softening temperature of 587.14 deg.C and a low softening point, which can promote sintering of the material. The material has the saturation magnetization of 4620Gs and the dielectric loss tangent less than or equal to 1.22 multiplied by 10^-3The ferromagnetic resonance line width Δ H is 378 Oe.

Example 3

Provides a compound of the formula Li_0.37Zn_0.24Cu_0.02Mn_0.02Fe_2.35O₄The Li spinel microwave ferrite and the preparation method thereof. Referring to the preparation steps of example 1, only the kinds and the proportions of the glass components, specifically SiO, were adjusted₂56 wt% of B₂O₃20 wt% of CaO, 10 wt% of M is PbO, ZnO and Na₂O、K₂O mixture, the mixture content being 14% by weight, the other process parameters being unchanged.

The glass powder has a DSC curve shown in FIG. 2, and has a softening temperature of 579.46 deg.C and a low softening point, which can promote sintering of the material. The material has a saturation magnetization of 4570Gs and a dielectric loss tangent less than or equal to 1.34 multiplied by 10^-3The ferromagnetic resonance line width Δ H is 360 Oe.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.