CN-122000163-A - Neodymium-cobalt co-substituted M-type strontium ferrite dual-band wave-absorbing material and preparation method thereof

Abstract

The invention relates to the technical field of electromagnetic wave absorbing materials, in particular to a neodymium-cobalt co-substituted M-type strontium ferrite dual-band wave absorbing material and a preparation method thereof. The chemical formula of the body dual-band wave absorbing material is Sr 1‑x Nd x Co 0.2 Fe 11.8 O 19 , wherein x=0.1-0.4. The method adopts strontium source, neodymium source, cobalt source and iron source and citric acid monohydrate to form sol, and the target product is obtained through ammonia water to regulate pH, heating to glue, drying and grinding, and then heat treatment at 250 ℃, 450 ℃ and 1400 ℃. After being compounded with paraffin, the obtained material can show wave-absorbing response in wave bands of 2-18GHz and 26.5-40GHz, and can be used as wave-absorbing filler for electromagnetic protection materials.

Inventors

• CUI JIEWU
• Feng Menglei
• ZHANG YONG
• WU YUCHENG

Assignees

• 合肥工业大学

Dates

Publication Date

20260508

Application Date

20260409

Claims (7)

1. 1. The neodymium-cobalt co-substituted M-type strontium ferrite dual-band wave-absorbing material is characterized in that the chemical formula of the wave-absorbing material is Sr 1-x Nd x Co 0.2 Fe 11.8 O 19 , wherein x=0.1-0.4.
2. 2. A method for preparing the neodymium-cobalt co-substituted M-type strontium ferrite dual-band wave-absorbing material according to claim 1, which is characterized by comprising the following steps: S1, mixing strontium nitrate, neodymium nitrate, cobalt nitrate, ferric nitrate, citric acid monohydrate and deionized water to form light brown transparent sol; S2, heating the sol obtained in the step S1 to react to form wet gel, drying and grinding to obtain precursor powder; and S3, carrying out heat treatment on the precursor powder obtained in the step S2, cooling to room temperature, and finely grinding to obtain the neodymium-cobalt co-substituted M-type strontium ferrite dual-band wave-absorbing material.
3. 3. The method according to claim 2, wherein the strontium nitrate, neodymium nitrate, cobalt nitrate and iron nitrate are added in the form of hydrate in step S1.
4. 4. The method according to claim 2, wherein the molar ratio of strontium nitrate, neodymium nitrate, cobalt nitrate, iron nitrate and citric acid monohydrate in step S1 is (1-x): x:0.2:11.8:14, wherein x = 0.1-0.4.
5. 5. The method according to claim 2, wherein the heating temperature in step S2 is 120 ℃ for 3.5 to 4.5 hours with a stirring speed of 500rpm.
6. 6. The method according to claim 2, wherein the drying temperature in step S2 is 120 ℃ and the drying time is 15 hours.
7. 7. The preparation method according to claim 2, wherein the specific position of the heat treatment process in step S3 is firstly heated from room temperature to 250 ℃ for 1h, then heated to 450 ℃ for 2h, finally heated to 1400 ℃ for 3h, and the heating rate is 5 ℃/min.

Description

Neodymium-cobalt co-substituted M-type strontium ferrite dual-band wave-absorbing material and preparation method thereof Technical Field The invention relates to the technical field of electromagnetic wave absorbing materials, in particular to a neodymium-cobalt co-substituted M-type strontium ferrite dual-band wave absorbing material and a preparation method thereof. Background The M-type strontium ferrite has been widely focused in the fields of permanent magnet materials, microwave devices and electromagnetic wave absorption due to the high magnetocrystalline anisotropy field, proper saturation magnetization and good chemical stability. With the rapid development of fifth generation mobile communication technology, millimeter wave radar and intelligent electronic equipment, the electromagnetic wave frequency range is continuously expanded to a higher range, the problems of electromagnetic interference and electromagnetic radiation pollution are increasingly outstanding, and the application requirements of wideband, thinness and strong absorption are provided for the wave absorbing material. By means of the characteristic natural resonance characteristic of the M-type strontium ferrite, remarkable magnetic loss can be generated in a microwave high-frequency band, electromagnetic wave energy is converted into heat energy to be dissipated, and the M-type strontium ferrite has the basic condition of becoming a high-performance wave absorbing material. However, the conventional M-type strontium ferrite has obvious limitation in electromagnetic parameter regulation and control. The complex dielectric constant and complex magnetic permeability of the material are difficult to realize good impedance matching, so that electromagnetic waves are difficult to effectively enter the material to be dissipated, most of incident waves are reflected on the surface of the material, and the wave absorption efficiency is severely limited. Meanwhile, the single-component M-type strontium ferrite has a narrow effective absorption frequency band, is difficult to cover the multi-frequency band working requirements related to modern electronic equipment, particularly has obviously reduced wave absorption performance in a millimeter wave band, and limits the application and popularization of the single-component M-type strontium ferrite in the fields of high-end electronic countermeasure, covert communication, automobile anti-collision radar and the like. To improve the electromagnetic properties of M-type strontium ferrites, researchers have attempted to modify the material by means of ion substitution. Transition metal ions such as cobalt, titanium, zinc and the like are introduced into ferrite lattices to partially replace iron ions so as to adjust magnetocrystalline anisotropy and saturation magnetization, thereby optimizing magnetic loss characteristics. Rare earth elements are also used for replacing strontium sites due to the unique 4f electron layer structure, and the regulation and control of magnetic anisotropy field and coercive force are realized by introducing lattice distortion and enhancing spin-orbit coupling action. The existing research shows that the substitution of a single element can improve the wave absorbing performance in a specific frequency band, but the adjusting range of electromagnetic parameters is still limited, and the requirements of impedance matching and loss enhancement are difficult to meet in a wider frequency band. In recent years, research ideas of rare earth and transition metal co-substitution modification are increasingly paid attention to. In theory, the synergistic effect of two ions is expected to realize finer regulation and control on the electromagnetic performance of the material, rare earth elements mainly influence magnetocrystalline anisotropy and dielectric polarization behaviors, and transition metals act on magnetic moment arrangement and natural resonance characteristics more. However, the existing co-doping research mostly adopts a synchronous substitution mode, namely two types of ions are simultaneously introduced according to a fixed proportion, and deep knowledge on the occupation behavior, interaction mechanism and comprehensive influence on electromagnetic parameters of the ions in a crystal lattice is lacking. Because the substitution sites of the two types of ions are different, the difference exists in the regulation and control paths of the magnetic structure, the blind composite doping often causes larger performance fluctuation, the expected synergistic enhancement effect is difficult to realize, and even the conditions that the magnetic properties cancel each other and the wave absorption frequency band is narrowed are occurred. Aiming at the problems, how to establish a systematic ion substitution modification strategy so that the material can keep excellent impedance matching and loss characteristics under different frequency bands becomes a technical probl