Abstract: Lithium-zinc ferrite hollow microspheres (LiZn FHMs) containing special surface crystals were synthesized by self-reactive quenching technology. The samples were heat-treated at 1200 °C and held for 4 h. The influence of the heat-treatment on LiZn FHMs was studied. The results show that the surface of hollow microspheres is smooth without heat-treatment. The phase components are Fe₂O₃, Fe₃O₄, Li_0.435Zn_0.195Fe_2.37O₄, and Li_0.5Fe_2.5O₄. The minimum reflectivity is −13.5 dB, and the corresponding frequency is 7.5 GHz. The effective absorption band lower than −10 dB is 6.2–8.5 GHz, and the bandwidth is 2.3 GHz. After heat-treatment, crystals on the surface of hollow microspheres grow significantly. Multiple-shape micro-nano crystals containing triangular, polygonal, and irregular crystal are generated. However, the phase composition does not change. The real part of the permittivity (e′), the imaginary part of permittivity (e″), the real part of permeability (µ′), and the imaginary part of permeability (µ″) all increase, and the microwave absorption properties at low frequency are significantly increased, with the absorption peak moving to a lower frequency range. The minimum reflectivity is −26.5 dB, and the corresponding frequency changes to 3.4 GHz. The effective absorption band is 2.6–4 GHz, and the bandwidth is 1.4 GHz.

热处理对自反应淬熄法制备低频LiZn铁氧体空心微珠的影响

[1]Cai XD, Wang JJ, Xu BC, et al., 2013. Effect of heat-treatment temperature on structure and microwave electromagnetic properties of hollow multiphase ceramic microspheres. Journal of the Chinese Ceramic Society, 41:1331-1338 (in Chinese).

[2]Cai XD, Wang JJ, Liang GH, et al., 2015a. Effect of NaNO₃ foaming agent on barium ferrite hollow microspheres prepared by self-reactive quenching technology. Journal of Alloys and Compounds, 636:348-356.

[3]Cai XD, Wang JJ, Yang RX, et al., 2015b. Influence of the foaming agent on the particle size and microwave absorption properties of hollow ceramic microspheres. International Journal of Applied Ceramic Technology, 12: E8-E16.

[4]Cai XD, Wang JJ, Xu BC, et al., 2015c. Preparation of LiZn ferrites hollow microspheres based self-reactive quenching technology and study on their low-frequency microwave absorption properties. Rare Metal Materials and Engineering, 391:2335-2339.

[5]Feng YB, Tang CM, Qiu T, 2013. Effect of ball milling and moderate surface oxidization on the microwave absorption properties of FeSiAl composites. Materials Science and Engineering: B, 178(16):1005-1011.

[6]Gruskova A, Slama J, Dosoudil R, 2008. Microwave properties of some substituted LiZn ferrites. Journal of Magnetism and Magnetic Materials, 320(20):e860-e864.

[7]Hu GX, Cai X, Rong YH, 2010. Fundamentals of Materials Science. Shanghai Jiao Tong University Press, Shanghai, China, p.20-22 (in Chinese).

[8]Jiang H, Guo Z, Zhao L, et al., 2010. Preparation and microwave absorption properties of LiZn ferrite. Journal of Inorganic Materials, 25(1):73-76.

[9]Lan YH, Gao XX, Bao XQ, 2007. Study of barium ferrite based on self-propagating high-temperature synthesis. Materials Review, 21:333-335.

[10]Liu CY, Lan ZW, Jiang XN, et al., 2008. Effects of sintering temperature on the microstructure and magnetic properties of LiZn ferrites. Journal of Magnetism and Magnetic Materials, 39:36-38.

[11]Liu SH, Guo HJ, 2002. Electromagnetic shielding and wave-absorbing materials. Journal of Functional Materials and Devices, 8:213-216.

[12]Liu SH, Liu JM, Dong XL, 2007. Electromagnetic Wave Shielding and Absorbent. Chemical Industrial Press, Beijing, China, p.67-70 (in Chinese).

[13]Lou HF, 2014. Designing, Synthesis and Study on High-frequency Absorbing Performance of Ferrite Hollow Microspheres by Self-reactive Quenching Technology. MS Thesis, Mechanical Engineering College, Shijiazhuang, China (in Chinese).

[14]Qu LY, 2009. Preparation and properties of low frequency band absorbing material. Modern Defense Technology, 37:131-133.

[15]Si Q, Dong FQ, 2006. Study on electromagnetic shielding effectiveness in low frequency of coatings doping aggregate and iron carbonyl. Functional Materials, 37: 883-892.

[16]Sun C, 2007. Synthesis and Microwave Absorbing Properties of Low Frequency Absorber. MS Thesis, Shandong University, Jinan, China (in Chinese).

[17]Sun C, Sun KN, 2007. Preparation and characterization of magnesium-substituted LiZn ferrites by a sol-gel method. Physical Review B, 391:335-338.

[18]Tong SY, Wu JM, Tung MJ, et al., 2012. Effect of Ni concentration on electromagnetic wave absorption of (Ni, Mn, Zn)Fe₂O₄/resin particulate composites. Journal of Alloys and Compounds, 525:143-148.

[19]Xia DG, Lu BS, Wang HK, 2010. Preparation Principle and Technology of Soft Magnetic Ferrites. Shaanxi Press, Xi’an, China, p.325-327 (in Chinese).

[20]Xie GZ, Yuan LK, Wang P, et al., 2010. GHz microwave properties of melt spun Fe-Si alloys. Journal of Non-crystalline Solids, 356(2):83-86.

[21]Yang M, 2010. Technology Handbook of Heat-treatment. China Machine Press, Beijing, China, p.124-126 (in Chinese).

[22]Yin C, Stark B, Chen YQ, et al., 2013. Adaptive minimum energy cognitive lighting control: integer order vs fractional order strategies in sliding mode based extremum seeking. Mechatronics, 23(7):863-872.

[23]Yu J, Chen SJ, Chen X, et al., 2015. Experimental investigation on mechanical properties and permeability evolution of red sandstone after heat treatments. Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 16(9):749-759.

[24]Yu Z, Chen DZ, Lan ZW, et al., 2007. Effect of Bi₂O₃ on properties of LiZn ferrites. Journal of Inorganic Materials, 22:1173-1177.

[25]Zan MSD, Kato I, Ab-Rahman MS, et al., 2009. Characterization of a-Si:H/SiN multilayer waveguide polarization using an optical pumping application-LED. Journal of Zhejiang University-SCIENCE A, 10(10):1421-1427.

[26]Zhang KC, Zhang LH, 1981. Crystal Growth. Science Press, Beijing, China, p.232-233 (in Chinese).

[27]Zhang ZQ, Li TH, Jing DQ, 2007. Present status and perspectives of the radar absorbing material. Materials Review, 21:307-310.