CN108934155B - Ferrite-based low-frequency electromagnetic wave-absorbing material and preparation method thereof - Google Patents
Ferrite-based low-frequency electromagnetic wave-absorbing material and preparation method thereof Download PDFInfo
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- CN108934155B CN108934155B CN201811114062.XA CN201811114062A CN108934155B CN 108934155 B CN108934155 B CN 108934155B CN 201811114062 A CN201811114062 A CN 201811114062A CN 108934155 B CN108934155 B CN 108934155B
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- 229910000859 α-Fe Inorganic materials 0.000 title claims abstract description 43
- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- 239000011358 absorbing material Substances 0.000 title claims abstract description 24
- 229910001308 Zinc ferrite Inorganic materials 0.000 claims abstract description 66
- KUJOABUXCGVGIY-UHFFFAOYSA-N lithium zinc Chemical compound [Li].[Zn] KUJOABUXCGVGIY-UHFFFAOYSA-N 0.000 claims abstract description 66
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 41
- 239000002245 particle Substances 0.000 claims abstract description 33
- 229910052742 iron Inorganic materials 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 10
- 238000003980 solgel method Methods 0.000 claims abstract description 8
- 238000011065 in-situ storage Methods 0.000 claims abstract description 5
- 230000009467 reduction Effects 0.000 claims abstract description 5
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 39
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 36
- 229910052751 metal Inorganic materials 0.000 claims description 27
- 239000002184 metal Substances 0.000 claims description 27
- 239000012279 sodium borohydride Substances 0.000 claims description 27
- 229910000033 sodium borohydride Inorganic materials 0.000 claims description 27
- 239000012266 salt solution Substances 0.000 claims description 25
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 24
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 23
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 23
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 23
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 20
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 claims description 20
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 claims description 17
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 claims description 16
- 229910052684 Cerium Inorganic materials 0.000 claims description 15
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 15
- 239000008367 deionised water Substances 0.000 claims description 15
- 229910021641 deionized water Inorganic materials 0.000 claims description 15
- 239000000499 gel Substances 0.000 claims description 15
- 239000000243 solution Substances 0.000 claims description 15
- 238000003756 stirring Methods 0.000 claims description 15
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 13
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 13
- 150000002736 metal compounds Chemical class 0.000 claims description 13
- 239000007864 aqueous solution Substances 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 10
- 239000011790 ferrous sulphate Substances 0.000 claims description 10
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 10
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 10
- 239000000843 powder Substances 0.000 claims description 10
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 239000011240 wet gel Substances 0.000 claims description 8
- 229910052725 zinc Inorganic materials 0.000 claims description 8
- 239000011701 zinc Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 7
- 238000005303 weighing Methods 0.000 claims description 7
- 230000009471 action Effects 0.000 claims description 5
- 239000007795 chemical reaction product Substances 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 5
- 239000012467 final product Substances 0.000 claims description 5
- 238000000227 grinding Methods 0.000 claims description 5
- 238000003760 magnetic stirring Methods 0.000 claims description 5
- 229910021645 metal ion Inorganic materials 0.000 claims description 5
- 239000011259 mixed solution Substances 0.000 claims description 5
- 230000007935 neutral effect Effects 0.000 claims description 5
- 238000007747 plating Methods 0.000 claims description 5
- 239000000376 reactant Substances 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- 238000001291 vacuum drying Methods 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- 238000001354 calcination Methods 0.000 claims description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000001509 sodium citrate Substances 0.000 claims description 3
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims description 3
- 239000011258 core-shell material Substances 0.000 abstract description 11
- 238000010521 absorption reaction Methods 0.000 abstract description 10
- 239000006096 absorbing agent Substances 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 5
- 238000003837 high-temperature calcination Methods 0.000 abstract description 4
- 239000002105 nanoparticle Substances 0.000 abstract description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- LEQAOMBKQFMDFZ-UHFFFAOYSA-N glyoxal Chemical compound O=CC=O LEQAOMBKQFMDFZ-UHFFFAOYSA-N 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- FUSNOPLQVRUIIM-UHFFFAOYSA-N 4-amino-2-(4,4-dimethyl-2-oxoimidazolidin-1-yl)-n-[3-(trifluoromethyl)phenyl]pyrimidine-5-carboxamide Chemical compound O=C1NC(C)(C)CN1C(N=C1N)=NC=C1C(=O)NC1=CC=CC(C(F)(F)F)=C1 FUSNOPLQVRUIIM-UHFFFAOYSA-N 0.000 description 2
- ZVNPWFOVUDMGRP-UHFFFAOYSA-N 4-methylaminophenol sulfate Chemical compound OS(O)(=O)=O.CNC1=CC=C(O)C=C1.CNC1=CC=C(O)C=C1 ZVNPWFOVUDMGRP-UHFFFAOYSA-N 0.000 description 2
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 description 2
- QXNVGIXVLWOKEQ-UHFFFAOYSA-N Disodium Chemical compound [Na][Na] QXNVGIXVLWOKEQ-UHFFFAOYSA-N 0.000 description 2
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical class OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 2
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 2
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- FTDUHBOCJSQEKS-UHFFFAOYSA-N borane;n-methylmethanamine Chemical compound B.CNC FTDUHBOCJSQEKS-UHFFFAOYSA-N 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 239000008139 complexing agent Substances 0.000 description 2
- 229960002089 ferrous chloride Drugs 0.000 description 2
- 229940015043 glyoxal Drugs 0.000 description 2
- 239000012493 hydrazine sulfate Substances 0.000 description 2
- 229910000377 hydrazine sulfate Inorganic materials 0.000 description 2
- 150000002505 iron Chemical class 0.000 description 2
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 2
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 2
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 2
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 2
- 239000002135 nanosheet Substances 0.000 description 2
- LJCNRYVRMXRIQR-OLXYHTOASA-L potassium sodium L-tartrate Chemical compound [Na+].[K+].[O-]C(=O)[C@H](O)[C@@H](O)C([O-])=O LJCNRYVRMXRIQR-OLXYHTOASA-L 0.000 description 2
- 229940074439 potassium sodium tartrate Drugs 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000001488 sodium phosphate Substances 0.000 description 2
- 229910000162 sodium phosphate Inorganic materials 0.000 description 2
- 235000011006 sodium potassium tartrate Nutrition 0.000 description 2
- ZAWGLAXBGYSUHN-UHFFFAOYSA-M sodium;2-[bis(carboxymethyl)amino]acetate Chemical compound [Na+].OC(=O)CN(CC(O)=O)CC([O-])=O ZAWGLAXBGYSUHN-UHFFFAOYSA-M 0.000 description 2
- 125000000383 tetramethylene group Chemical group [H]C([H])([*:1])C([H])([H])C([H])([H])C([H])([H])[*:2] 0.000 description 2
- UEUXEKPTXMALOB-UHFFFAOYSA-J tetrasodium;2-[2-[bis(carboxylatomethyl)amino]ethyl-(carboxylatomethyl)amino]acetate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-]C(=O)CN(CC([O-])=O)CCN(CC([O-])=O)CC([O-])=O UEUXEKPTXMALOB-UHFFFAOYSA-J 0.000 description 2
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005674 electromagnetic induction Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/0018—Mixed oxides or hydroxides
- C01G49/0063—Mixed oxides or hydroxides containing zinc
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Soft Magnetic Materials (AREA)
- Hard Magnetic Materials (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Abstract
The invention discloses a ferrite-based low-frequency electromagnetic wave-absorbing material and a preparation method thereof, wherein the ferrite-based low-frequency electromagnetic wave-absorbing material comprises the following components: the ferrite-based low-frequency electromagnetic wave-absorbing particles are of a similar core-shell structure; the core-shell structure comprises micron-sized lithium zinc ferrite particles and nano-sized iron sheets. The preparation method comprises the following steps: sol-gel method, high temperature calcination and in-situ reduction method; the lithium zinc ferrite is prepared by a sol-gel method and high-temperature calcination; and growing iron sheets on the surface of the prepared lithium zinc ferrite by an in-situ reduction method. The invention can provide an electromagnetic wave absorber based on lithium zinc ferrite; the lithium zinc ferrite has good electromagnetic wave absorption effect in the low-frequency electromagnetic wave band of 0.1-4 GHz.
Description
Technical Field
The invention relates to the technical field of electromagnetic wave absorption and protection, in particular to a ferrite-based low-frequency electromagnetic wave absorption material and a preparation method thereof.
Background
With the increasing play of the power industry in the aspects of society and life, the reliability requirement of modern society on power supply is higher and higher, and the status of power safety supply is more important than that of the prior art at any time. In recent years, with the increasing economic growth speed, the upgrading of power grid construction, the improvement of voltage level and the increase of electric power coverage area are promoted. With the wide use of various electronic devices and equipment with high sensitivity and large information amount in the links of power generation production, power transmission, power distribution, power utilization and the like of an electric power system, the electromagnetic environment (the electromagnetic environment refers to the sum of all electromagnetic phenomena existing in a given space range, including a natural electromagnetic environment and a man-made electromagnetic environment) of the electric power system is very complex and varied, and the problem of electromagnetic interference is increasingly serious. The interference of electromagnetic environment to power electronic equipment is mainly caused by electromagnetic interference caused by a large amount of electromagnetic waves radiated by electronic equipment in a power system when the electronic equipment works, overvoltage and electromagnetic induction generated by various operations, and the like. Therefore, the normal work of other surrounding electronic instruments is influenced and interfered, the performance of the electronic instruments is reduced or even fails, and the automatic control failure, the information transmission failure, the electric wave transmission interruption and the like of the system can be caused in serious cases, so that serious economic loss and casualties are directly or indirectly caused. In the electric power system of China, accidents caused by electromagnetic interference frequently occur, and consequently, huge economic loss is caused and normal living order of people is influenced. The electromagnetic environment faced by the current power system is increasingly severe, and it is necessary to solve the problems of electromagnetic compatibility (EMC) and protection of power electronic equipment while the power system and technology are developed at a high speed, so as to construct a good electromagnetic environment, and ensure that the power system can supply power safely and efficiently. However, the electromagnetic wave frequency band of the electronic power equipment interfering the power system is mainly concentrated below 4GHz, so that the preparation of low-frequency electromagnetic wave absorbing material is imminent.
Disclosure of Invention
In view of the above defects in the prior art, the present invention aims to provide a ferrite-based low-frequency electromagnetic wave-absorbing material and a preparation method thereof, which can provide an electromagnetic wave-absorbing agent based on lithium zinc ferrite; the lithium zinc ferrite has good electromagnetic wave absorption effect in the low-frequency electromagnetic wave band of 0.1-4 GHz.
One of the purposes of the invention is realized by the technical scheme, the ferrite-based low-frequency electromagnetic wave-absorbing material comprises: the ferrite-based low-frequency electromagnetic wave-absorbing particles are of a similar core-shell structure;
the core-shell structure comprises micron-sized lithium zinc ferrite particles and nano-sized iron sheets.
The other purpose of the invention is realized by the technical scheme, and the preparation method of the ferrite-based low-frequency electromagnetic wave-absorbing material comprises the following steps:
the preparation method comprises the following steps: sol-gel method, calcination at 1500 ℃ of 1000-;
the lithium zinc ferrite is prepared by a sol-gel method and high-temperature calcination;
and growing iron sheets on the surface of the prepared lithium zinc ferrite by an in-situ reduction method.
Further, the ferrite-based low-frequency electromagnetic wave-absorbing material is prepared by reacting lithium zinc ferrite particles, sodium borohydride, ferrous sulfate heptahydrate, polyvinylpyrrolidone (PVP) and sodium hydroxide.
Further, the concentration of each reactant of the ferrite-based low-frequency electromagnetic wave-absorbing material is as follows: 0.5-0.8 mol/L of lithium zinc ferrite particles, 1-1.5 mol/L of sodium borohydride, 0.05-0.1 mol/L of ferrous sulfate, 0.001-0.002 mol/L of PVP and 0.06-0.10 mol/L of sodium hydroxide.
Further, the preparation method comprises the following steps:
s1: dissolving sodium borohydride and sodium hydroxide powder in deionized water and forming transparent sodium borohydride aqueous solution under the action of magnetic stirring;
s2: adding a proper amount of lithium zinc ferrite particles, ferrous sulfate and PVP into deionized water, and mechanically stirring for 30 min;
s3: dropping a sodium borohydride aqueous solution and a mixed solution containing lithium zinc ferrite into a chemical plating reaction tank for full reaction;
s4: collecting the reaction product with a magnet, washing, drying, and grinding to obtain the final product: the surface of the lithium zinc ferrite powder is provided with nano iron sheets.
Further, the lithium zinc ferrite is prepared from a metal salt solution, sodium citrate and ammonia water.
Further, the lithium zinc ferrite comprises: lithium element, zinc element, iron element, cerium element and oxygen element;
the stoichiometric ratio of various elements is as follows: zinc: iron: cerium: 0-0.4% of oxygen: 0.1-1: 2-2.45: 0.2-0.7: 4;
the metal salt solution comprises lithium nitrate, zinc nitrate, ferric nitrate and cerous nitrate solution.
Further, the molar ratio of the total moles of metal ions in the metal salt solution to the citric acid molecules is 0.8-1.2.
Further, the preparation process of the lithium zinc ferrite comprises the following steps:
a. weighing quantitative metal compounds of lithium nitrate, zinc nitrate, ferric nitrate and cerium nitrate according to a specific stoichiometric ratio of the lithium zinc ferrite, dissolving the metal compounds in deionized water together, and electromagnetically stirring the metal compounds until a uniform transparent mixed metal salt solution is obtained;
b. sequentially adding citric acid and ammonia water into the transparent metal salt solution in the step (a), and stirring the solution and the ammonia water into sol under the assistance of electromagnetism, wherein the pH value of the solution or the sol is neutral by the dropwise added ammonia water;
c. placing the sol obtained in the step (b) in a water bath thermostat, and setting the temperature to be 60-80 ℃; after several hours, transferring the formed wet gel into a vacuum drying oven, and drying the wet gel into dry gel after 8-12 hours at the temperature of 120 ℃;
d. then the dried gel is placed in a horizontal tube furnace, the temperature rise rate is increased to 1000-1500 ℃ at 160, 200, 240 and 280 ℃/h to calcine the dried gel, and finally the lithium zinc ferrite doped with the rare earth element cerium is obtained by furnace cooling.
Due to the adoption of the technical scheme, the invention has the following advantages: the invention provides an electromagnetic wave absorbing agent based on lithium zinc ferrite. The lithium zinc ferrite has good electromagnetic wave absorption effect in the low-frequency electromagnetic wave band of 0.1-4 GHz. The lithium zinc ferrite material has good frequency characteristic, larger relative permeability and smaller relative dielectric constant, so that the lithium zinc ferrite has good electromagnetic wave absorption effect in a low-frequency electromagnetic wave band. Meanwhile, the ferrite has wide sources and is easy to obtain, and the preparation process is simple and easy to operate. The invention also dopes rare earth element cerium which is an element with unpaired electrons shielded by outermost layer electrons on the basis of the lithium zinc ferrite, so that atoms and ions of the rare earth element cerium have special electromagnetic properties. By utilizing the characteristics of the ferrite, the ferrite is doped and substituted, the electromagnetic characteristic parameters of the ferrite can be changed, the corresponding loss mechanism of a system is enhanced, and the purposes of improving wave-absorbing performance, expanding absorption bandwidth and meeting matching requirements are achieved. More importantly, in order to further enhance the intensity and absorption bandwidth of the wave absorber for better absorbing electromagnetic waves in a low-frequency band, the invention designs a similar core-shell structure, and a large number of nano-scale iron sheets grow on the surface of the cerium-doped ferrite. The nano sheet is beneficial to increasing the diffuse reflection of incident microwaves and bringing more interface charge polarization, so that the nano sheet has a wider absorption frequency range and stronger absorption intensity.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
The drawings of the invention are illustrated as follows:
FIG. 1 is a schematic diagram of a ferrite-based low-frequency electromagnetic wave-absorbing material.
Detailed Description
The invention is further illustrated by the following figures and examples.
Example, as shown in fig. 1; a ferrite-based low-frequency electromagnetic wave-absorbing material comprises: the ferrite-based low-frequency electromagnetic wave-absorbing particles are of a similar core-shell structure;
the core-shell structure comprises micron-sized lithium zinc ferrite particles and nano-sized iron sheets.
The other purpose of the invention is realized by the technical scheme, and the preparation method of the ferrite-based low-frequency electromagnetic wave-absorbing material comprises the following steps:
the preparation method comprises the following steps: sol-gel method, calcination at 1500 ℃ of 1000-;
the lithium zinc ferrite is prepared by a sol-gel method and high-temperature calcination;
and growing iron sheets on the surface of the prepared lithium zinc ferrite by an in-situ reduction method.
The ferrite-based low-frequency electromagnetic wave-absorbing material is prepared by reacting lithium zinc ferrite particles, sodium borohydride, ferrous sulfate heptahydrate, polyvinylpyrrolidone (PVP) and sodium hydroxide.
The concentration of each reactant of the ferrite-based low-frequency electromagnetic wave-absorbing material is as follows: 0.5-0.8 mol/L of lithium zinc ferrite particles, 1-1.5 mol/L of sodium borohydride, 0.05-0.1 mol/L of ferrous sulfate, 0.001-0.002 mol/L of PVP and 0.06-0.10 mol/L of sodium hydroxide.
The preparation method comprises the following steps:
s1: dissolving sodium borohydride and sodium hydroxide powder in deionized water and forming transparent sodium borohydride aqueous solution under the action of magnetic stirring;
s2: adding a proper amount of lithium zinc ferrite particles, ferrous sulfate and PVP into deionized water, and mechanically stirring for 30 min;
s3: dropping a sodium borohydride aqueous solution and a mixed solution containing lithium zinc ferrite into a chemical plating reaction tank for full reaction;
s4: collecting the reaction product with a magnet, washing, drying, and grinding to obtain the final product: the surface of the lithium zinc ferrite powder is provided with nano iron sheets.
The lithium zinc ferrite is prepared from a metal salt solution, sodium citrate and ammonia water.
The lithium zinc ferrite comprises: lithium element, zinc element, iron element, cerium element and oxygen element;
the stoichiometric ratio of various elements is as follows: zinc: iron: cerium: 0-0.4% of oxygen: 0.1-1: 2-2.45: 0.2-0.7: 4;
the metal salt solution comprises lithium nitrate, zinc nitrate, ferric nitrate and cerous nitrate solution.
The molar ratio of the total moles of metal ions in the metal salt solution to the citric acid molecules is 0.8-1.2.
The preparation steps of the lithium zinc ferrite are as follows:
a. weighing quantitative metal compounds of lithium nitrate, zinc nitrate, ferric nitrate and cerium nitrate according to a specific stoichiometric ratio of the lithium zinc ferrite, dissolving the metal compounds in deionized water together, and electromagnetically stirring the metal compounds until a uniform transparent mixed metal salt solution is obtained;
b. c, sequentially adding citric acid and ammonia water into the transparent metal salt solution in the step a, and stirring the solution and the ammonia water into sol under the assistance of electromagnetism, wherein the pH value of the solution or the sol is neutral by the dropwise added ammonia water;
c. b, placing the sol obtained in the step b in a water bath thermostat, and setting the temperature to be 60-80 ℃; after several hours, transferring the formed wet gel into a vacuum drying oven, and drying the wet gel into dry gel after 8-12 hours at the temperature of 120 ℃;
d. then the dried gel is placed in a horizontal tube furnace, the temperature rise rate is increased to 1000-1500 ℃ at 160, 200, 240 and 280 ℃/h to calcine the dried gel, and finally the lithium zinc ferrite doped with the rare earth element cerium is obtained by furnace cooling.
Example 1, a ferrite-based electromagnetic wave absorber was prepared;
the lithium zinc ferrite particles of the present example have the following stoichiometric ratios of the components:
stoichiometric ratio of each element of metal salt solution lithium: zinc: iron: cerium: oxygen 0.4: 0.2: 2.35:0.3: 4;
the metal salt solution comprises lithium nitrate, zinc nitrate, ferric nitrate and cerous nitrate solution;
the molar ratio of the total moles of metal ions in the metal salt solution to the citric acid molecules is 1.
The invention also provides a preparation method of the lithium zinc ferrite, which comprises the following steps:
a. weighing quantitative metal compounds such as lithium nitrate, zinc nitrate, ferric nitrate, cerium nitrate and the like according to the specific stoichiometric ratio of the lithium zinc ferrite, dissolving the metal compounds together in deionized water, and electromagnetically stirring the mixture until a uniform and transparent mixed metal salt solution is obtained.
b. Weighing a citric acid solution according to the total mole number of the metal salt in the step (a), and adding citric acid and ammonia water into the transparent metal salt solution in the step (a) in sequence with electromagnetic stirring. The ammonia is added dropwise in such an amount that the solution/sol is neutral in ph.
c. Placing the sol obtained in the step (b) in a water bath thermostat, and setting the temperature to be 70 ℃. After several hours, the formed wet gel is transferred into a vacuum drying oven and dried into dry gel after 8-12 hours at the temperature of 120 ℃.
d. Then the dried gel is placed in a horizontal tube furnace, the temperature is raised to 1200 ℃ at the heating rate of 160, 200, 240 or 280 ℃/h to calcine the dried gel, and finally the lithium zinc ferrite doped with the rare earth element cerium is obtained after furnace cooling.
In the embodiment, the preparation of the ferrite-based low-frequency electromagnetic wave-absorbing particles comprises 0.6mol/L of lithium zinc ferrite particles, 1.4mol/L of sodium borohydride, 0.05mol/L of ferrous sulfate, 0.002mol/L of PVP0 and 0.06mol/L of sodium hydroxide according to the concentration of reactants.
The preparation method of the ferrite-based low-frequency electromagnetic wave-absorbing particles in the embodiment specifically comprises the following steps:
a. dissolving sodium borohydride and sodium hydroxide powder in deionized water and forming transparent sodium borohydride aqueous solution under the action of magnetic stirring;
b, adding a proper amount of lithium zinc ferrite particles, ferrous sulfate and PVP into deionized water, and mechanically stirring for 30 min.
c. Dropping a sodium borohydride aqueous solution and a mixed solution containing lithium zinc ferrite into a chemical plating reaction tank for full reaction;
e. collecting the reaction product with a magnet, washing, drying, and grinding to obtain the final product: the surface of the lithium zinc ferrite powder is provided with nano iron sheets.
In this embodiment, the reducing agent is sodium borohydride. Under the same operation condition, replacing sodium borohydride by formaldehyde, potassium sodium tartrate, hydrazine sulfate, glyoxal, dimethyl ammonia borane and metol according to the same molar ratio concentration; or replacing the mixture with two or more than two according to the same weight percentage to obtain the qualified flower-shaped carbonyl iron particles.
In this embodiment, the iron salt is ferrous sulfate heptahydrate. Under the same operation condition, replacing ferrous sulfate heptahydrate with at least one of ferric chloride, ferric sulfate, ferrous chloride and ferric nitrate according to the same molar concentration to obtain the ferrite-based low-frequency wave-absorbing particles with similar core-shell structures.
In this embodiment, the complexing agent is polyvinylpyrrolidone (PVP). Under the same operation condition, replacing polyvinylpyrrolidone (PVP) with sodium aminotriacetate (NTA), ethylene diamine tetraacetic acid salt (disodium or tetrasodium EDTA), diethylenetriamine pentacarboxylate (DTPA) and ethylene diamine tetramethylene sodium phosphate (EDTMPS) according to the same molar concentration; or two or more mixtures are replaced according to the same molar concentration to obtain the ferrite-based low-frequency wave-absorbing particles with similar core-shell structures.
Example 2, a ferrite-based electromagnetic wave absorber was prepared;
the lithium zinc ferrite particles of the present example have the following stoichiometric ratios of the components:
stoichiometric ratio of each element of metal salt solution lithium: zinc: iron: cerium: oxygen 0.25: 0.5: 2.3:0.2: 4;
the metal salt solution comprises lithium nitrate, zinc nitrate, ferric nitrate and cerous nitrate solution;
the molar ratio of the total moles of metal ions in the metal salt solution to the citric acid molecules is 1.
The invention also provides a preparation method of the lithium zinc ferrite, which comprises the following steps:
a. weighing quantitative metal compounds such as lithium nitrate, zinc nitrate, ferric nitrate, cerium nitrate and the like according to the specific stoichiometric ratio of the lithium zinc ferrite, dissolving the metal compounds together in deionized water, and electromagnetically stirring the mixture until a uniform and transparent mixed metal salt solution is obtained.
b. Weighing a citric acid solution according to the total mole number of the metal salt in the step (a), and adding citric acid and ammonia water into the transparent metal salt solution in the step (a) in sequence with electromagnetic stirring. The ammonia is added dropwise in such an amount that the solution/sol is neutral in ph.
c. Placing the sol obtained in the step (b) in a water bath thermostat, and setting the temperature to be 70 ℃. After several hours, the formed wet gel is transferred into a vacuum drying oven and dried into dry gel after 8-12 hours at the temperature of 120 ℃.
d. Then the dried gel is placed in a horizontal tube furnace, the temperature is raised to 1100 ℃ at the heating rate of 160, 200, 240 or 280 ℃/h to calcine the dried gel, and finally the lithium zinc ferrite doped with the rare earth element cerium is obtained after furnace cooling.
In the embodiment, the preparation of the ferrite-based low-frequency electromagnetic wave-absorbing particles comprises 0.6mol/L of lithium zinc ferrite particles, 1.4mol/L of sodium borohydride, 0.05mol/L of ferrous sulfate, 0.002mol/L of PVP0 and 0.06mol/L of sodium hydroxide according to the concentration of reactants.
The preparation method of the ferrite-based low-frequency electromagnetic wave-absorbing particles in the embodiment specifically comprises the following steps:
a. dissolving sodium borohydride and sodium hydroxide powder in deionized water and forming transparent sodium borohydride aqueous solution under the action of magnetic stirring;
b. and adding a proper amount of lithium zinc ferrite particles, ferrous sulfate and PVP into deionized water, and mechanically stirring for 30 min.
c. Dropping a sodium borohydride aqueous solution and a mixed solution containing lithium zinc ferrite into a chemical plating reaction tank for full reaction;
e. collecting the reaction product with a magnet, washing, drying, and grinding to obtain the final product: the surface of the lithium zinc ferrite powder is provided with nano iron sheets.
In this embodiment, the reducing agent is sodium borohydride. Under the same operation condition, replacing sodium borohydride by formaldehyde, potassium sodium tartrate, hydrazine sulfate, glyoxal, dimethyl ammonia borane and metol according to the same molar ratio concentration; or replacing the mixture with two or more than two according to the same weight percentage to obtain the qualified flower-shaped carbonyl iron particles.
In this embodiment, the iron salt is ferrous sulfate heptahydrate. Under the same operation condition, replacing ferrous sulfate heptahydrate with at least one of ferric chloride, ferric sulfate, ferrous chloride and ferric nitrate according to the same molar concentration to obtain the ferrite-based low-frequency wave-absorbing particles with similar core-shell structures.
In this embodiment, the complexing agent is polyvinylpyrrolidone (PVP). Under the same operation condition, replacing polyvinylpyrrolidone (PVP) with sodium aminotriacetate (NTA), ethylene diamine tetraacetic acid salt (disodium or tetrasodium EDTA), diethylenetriamine pentacarboxylate (DTPA) and ethylene diamine tetramethylene sodium phosphate (EDTMPS) according to the same molar concentration; or two or more mixtures are replaced according to the same molar concentration to obtain the ferrite-based low-frequency wave-absorbing particles with similar core-shell structures.
The invention has the advantages that: the electromagnetic wave-absorbing particles based on the ferrite prepared by the invention have good electromagnetic wave-absorbing effect in a low-frequency electromagnetic band, and mainly absorb the frequency band of 0.1-4 GHz. The electromagnetic wave absorbing particles are mainly researched and developed aiming at the electromagnetic interference problem of various civil electronic power equipment, and can absorb electromagnetic waves radiated by radar, television broadcast transmitting systems, radio frequency and microwave treatment equipment, microwave ovens, electromagnetic ovens, computers, televisions, mobile phones and the like.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (7)
1. A preparation method of a ferrite-based low-frequency electromagnetic wave-absorbing material is characterized by comprising the following steps: sol-gel method, calcination at 1500 ℃ of 1000-;
preparing lithium zinc ferrite by a sol-gel method and calcination at the temperature of 1000-1500 ℃;
growing iron sheets on the surface of the prepared lithium zinc ferrite by an in-situ reduction method;
the lithium zinc ferrite comprises: lithium element, zinc element, iron element, cerium element and oxygen element;
the stoichiometric ratio of various elements is as follows: zinc: iron: cerium: 0-0.4% of oxygen: 0.1-1: 2-2.45: 0.2-0.7: 4;
the preparation method comprises the following steps:
s1: dissolving sodium borohydride and sodium hydroxide powder in deionized water and forming transparent sodium borohydride aqueous solution under the action of magnetic stirring;
s2: adding a proper amount of lithium zinc ferrite particles, ferrous sulfate and polyvinylpyrrolidone (PVP) into deionized water, and mechanically stirring for 30 min;
s3: dropping a sodium borohydride aqueous solution and a mixed solution containing lithium zinc ferrite into a chemical plating reaction tank for full reaction;
s4: collecting the reaction product with a magnet, washing, drying, and grinding to obtain the final product: the surface of the lithium zinc ferrite powder is provided with nano iron sheets.
2. The method for preparing the ferrite-based low-frequency electromagnetic wave-absorbing material according to claim 1, wherein the ferrite-based low-frequency electromagnetic wave-absorbing material is prepared by reacting lithium zinc ferrite particles, sodium borohydride, ferrous sulfate heptahydrate, polyvinylpyrrolidone (PVP) and sodium hydroxide.
3. The method for preparing the ferrite-based low-frequency electromagnetic wave-absorbing material according to claim 2, wherein the concentration of each reactant of the ferrite-based low-frequency electromagnetic wave-absorbing material is as follows: 0.5-0.8 mol/L of lithium zinc ferrite particles, 1-1.5 mol/L of sodium borohydride, 0.05-0.1 mol/L of ferrous sulfate, 0.001-0.002 mol/L of PVP and 0.06-0.10 mol/L of sodium hydroxide.
4. The method for preparing the ferrite-based low-frequency electromagnetic wave-absorbing material as claimed in claim 1, wherein the lithium zinc ferrite is prepared from a metal salt solution, sodium citrate and ammonia water.
5. The method for preparing the ferrite-based low-frequency electromagnetic wave-absorbing material as claimed in claim 4, wherein the metal salt solution comprises lithium nitrate, zinc nitrate, ferric nitrate and cerium nitrate solutions.
6. The method for preparing the ferrite-based low-frequency electromagnetic wave absorbing material as claimed in claim 4, wherein the molar ratio of the total moles of metal ions in the metal salt solution to the citric acid molecules is 0.8-1.2.
7. The preparation method of the ferrite-based low-frequency electromagnetic wave-absorbing material as claimed in claim 1, wherein the preparation steps of the lithium zinc ferrite are as follows:
a. weighing quantitative metal compounds of lithium nitrate, zinc nitrate, ferric nitrate and cerium nitrate according to a preset stoichiometric ratio of the lithium zinc ferrite, dissolving the metal compounds in deionized water together, and electromagnetically stirring the metal compounds until a uniform transparent mixed metal salt solution is obtained;
b. b, sequentially adding citric acid and ammonia water into the metal salt solution in the step a, and stirring the mixture into sol under the assistance of electromagnetism, wherein the dropwise added ammonia water can enable the pH value of the solution or the sol to be neutral;
c. b, placing the sol obtained in the step b in a water bath thermostat, and setting the temperature to be 60-80 ℃; after several hours, transferring the formed wet gel into a vacuum drying oven, and drying the wet gel into dry gel after 8-12 hours at the temperature of 120 ℃;
d. then the dried gel is placed in a horizontal tube furnace, the temperature is raised to 1000-1500 ℃ at the heating rate of 160, 200, 240 or 280 ℃/h to calcine the dried gel, and finally the lithium zinc ferrite doped with the rare earth element cerium is obtained by furnace cooling.
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