Temperature-regulated high-entropy Fe_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2Fe₂O₄ ferrites for superior microwave absorption properties

Abstract

The high-entropy strategy has recently gained significant attention as an effective approach for enhancing microwave absorption performance. In this paper, a simple hydrothermal method followed by calcination was used to synthesize Fe_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2Fe₂O₄ high-entropy spinel ferrite for microwave absorption. The effects of calcination temperature on the microstructure and microwave absorption performance of the material were systematically investigated. Phase analysis reveals that a pure spinel ferrite phase with microwave absorption capability forms at 400°C, while minor maghemite impurities emerge at 800°C. As temperature rises, the effective absorption bandwidth first increases and then decreases, with its frequency range shifting toward higher frequencies. The sample calcined at 400°C achieves an excellent reflection loss of −77.48 dB with an effective absorption bandwidth of 3.74 GHz. The sample optimized at 800°C exhibits an excellent absorption bandwidth of 6.71 GHz (10.61–17.32 GHz), along with a minimum reflection loss of −31.17 dB at a thickness of only 2.19 mm. It also demonstrates a significant radar cross-section reduction of 26.04 dB·m². The excellent microwave absorption performance is primarily attributed to enhanced dipole polarization induced by the high-entropy effect, favorable electrical conductivity, effective magnetic loss, and adequate impedance matching. This work provides a good example for constructing high-performance spinel oxides through high-entropy strategies, demonstrating significant potential in the development of advanced microwave absorption materials.

Keywords

high-entropy ceramics / spinel ferrite / microwave absorption / calcination temperature / radar cross-section

References

[1] Singh S, Kumar A, Singh D. Enhanced microwave absorption performance of SWCNT/SiC composites. J. Electron. Mater., 2020, 49(12):7279.

[2] X.J. Han, Y.F. Feng, N. Zhang, et al., Bio-based multifunctional carbon aerogels for ultrawide electromagnetic wave absorption and thermal insulation, Carbon, 388(0225), art. No. 120231.

[3] J.X. Hu, W.R. Yan, C. Yi, et al., Optimized atomic occupancy unlocks high-temperature magnetic stability and electromagnetic wave absorption in Y₂Fe₉Co₈ alloys, J. Alloy. Compd., 1022(2025), art. No. 179907.

[4] Y.N. Shi, X.A. Li, J.J. Yang, et al, Controlling of pseudographite proportion in amorphous carbon to enhance dipole polarization for microwave absorption, J. Colloid Interface Sci., 691(2025), art. No. 137422.

[5] P. He, Q.Q. Zhou, Z. Chen, et al., Comparison of microwave absorption performance under solid and hollow structures of ferroferric oxide nanospheres, J. Phys. Chem. Solids, 203(2025), art. No. 112703.

[6] Z.Z. He, L.Z. Shi, R. Sun, et al., Low-temperature oxidation induced phase evolution with gradient magnetic heterointerfaces for superior electromagnetic wave absorption, Nano Micro Lett., 17(2024), No. 1, art. No. 7.

[7] Y.M. Lu, X.N. Zhao, Y. Lin, et al., in-situ growth of MoO₂/MoS₂ microspheres on reduced graphene oxide with enhanced dielectric polarization and impedance matching for boosting electromagnetic wave absorption, Carbon, 238(2025), art. No. 120298.

[8] W. Chen, Y.P. Duan, S.D. Gu, M. Zhang, and C.Y. Xia, Resonator-free metamaterials based on ferromagnetic dielectrics for mandatory microwave loss and compact stealth cloaks, Adv. Mater., 37(2025), No. 39, art. No. 2507366.

[9] Singh S, Sharma V. Improvement in magnetic behaviour on erbium addition to Co–Mn ferrite nanoparticles for magnetic device applications. Ceram. Int., 2025, 51(3):3714.

[10] Erdil T, Ozgur C, Geyikci U, Lokcu E, Toparli C. Earth-abundant divalent cation high-entropy spinel ferrites as bifunctional electrocatalysts for oxygen evolution and reduction reactions. ACS Appl. Energy Mater., 2024, 7(18):7775.

[11] S.P. Shao, S.Z. Xing, K. Bi, et al., Tailored multi-band microwave absorption performance via entropy engineering in spinel ferrite/carbon nanofiber composites, Small, 21(2025), No. 23, art. No. 2502349.

[12] S. Mandal, N. Sharma, S. Marik, and T. Chakraborty, Structural, microstructural, and dielectric properties of Al, Ga, and Cr based high-entropy spinel oxides, Solid State Commun., 404(2025), art. No. 116069.

[13] X.Y. Wang, B.Y. Cao, H.B. Yin, P.F. Yan, and T. Liu, Obtaining low-frequency and broadband absorbing ferrite@C microspheres through the high entropy engineering and construction of opened-hollow multi-shell architecture, Adv. Funct. Mater., 35(2025), No. 38, art. No. 2504653.

[14] N. Aggarwal and S.B. Narang, Effect of co-substitution of Co–Zr on electromagnetic properties of Ni–Zn spinel ferrites at microwave frequencies, J. Alloy. Compd., 866(2021), art. No. 157461.

[15] A. Radoń, L. Hawełek, D. Łukowiec, J. Kubacki, and P. Włodarczyk, Dielectric and electromagnetic interference shielding properties of high entropy (Zn,Fe,Ni,Mg,Cd)Fe₂O₄ ferrite, Sci. Rep., 9(2019), art. No. 20078.

[16] X.Y. Liu, Z.K. Zhang, F.Y. Wu, et al., Insight of multi-polarization effect by constructing high-entropy spinel ferrite/perovskite@amorphous carbon for enhancing electromagnetic wave absorption, Chem. Eng. J., 516(2025), art. No. 164053.

[17] X.Y. Liu, F.Y. Tian, J. Sheng, Y.S. Yu, and W.W. Yang, High-entropy porous spinel ferrite@amorphous carbon nanocomposites with abundant structural defects for wide-band electromagnetic wave absorption, Chem. Eng. J., 490(2024), art. No. 151848.

[18] B. Zhao, Y.Q. Du, Z.K. Yan, et al., Structural defects in phaseregulated high-entropy oxides toward superior microwave absorption properties, Adv. Funct. Mater., 33(2023), No. 1, art. No. 2209924.

[19] Ma JB, Zhao B, Xiang HM, et al.High-entropy spinel ferrites MFe₂O₄ (M = Mg, Mn, Fe, Co, Ni, Cu, Zn) with tunable electromagnetic properties and strong microwave absorption. J. Adv. Ceram., 2022, 11(5):754.

[20] Liu PY, Cui ZM, Sun Y, et al.Research on high-entropy spinel microwave absorption materials: Exploration of machine learning and experimental integration. Ceram. Int., 2024, 50(23):49906.

[21] G.H. Jin, C. Luo, Z.G. Wang, et al., Unraveling phase transition pathway of spinel (FeCoCrNiMn)₃O₄ high-entropy oxide anodes for long-life Li-ion batteries, Mater. Today Chem., 48(2025), art. No. 102949.

[22] T. Warski, J. Kubacki, D. Łukowiec, et al., Magnetodielectric and low-frequency microwave absorption properties of entropy stabilised ferrites and 3D printed composites, Composites Part B, 243(2022), art. No. 110126.

[23] Mohammadabadi FH, Masoudpanah SM, Alamolhoda S, Koohdar HR. Electromagnetic microwave absorption properties of high entropy spinel ferrite ((MnNiCuZn)_1−xCo_xFe₂O₄/graphene nanocomposites. J. Mater. Res. Technol., 2021, 14: 1099.

[24] Li MX, Ye XL, Guo SH, et al.High entropy design endows spinel compounds with excellent bifunctional catalysis for hydrogen production from water electrolysis. Int. J. Hydrogen Energy, 2025, 130: 644.

[25] Wang DD, Liu ZJ, Du SQ, et al.Low-temperature synthesis of small-sized high-entropy oxides for water oxidation. J. Mater. Chem. A, 2019, 7(42):24211.

[26] Chen HY, Tang ZP, Yin LJ, Zhang LB, Xu X. Low-frequency microwave absorption of CIPs@Mn_0.8Zn_0.2Fe₂O₄-CNTs composites. J. Inorg. Mater., 2024, 39(1):71.

[27] Zhao YM, Wang LH, Liu ZL, et al.Simple synthesis of hollow CoFe carbon fiber composites with enhanced heterogeneous interfaces and impedance matching for broadband microwave absorption. J. Mater. Sci. Technol., 2025, 238: 178.

[28] Ai JP, Shuai YP, Hu M, et al.Microstructural evolution and catalytic properties of novel high-entropy spinel ferrites MFe₂O₄ (M = Mg, Co, Ni, Cu, Zn). Ceram Int., 2023, 49(14):22941.

[29] McCormack SJ, Navrotsky A. Thermodynamics of high entropy oxides. Acta Mater., 2021, 202: 1.

[30] B. Zhao, Z.K. Yan, Y.Q. Du, et al., High-entropy enhanced microwave attenuation in titanate perovskites, Adv. Mater., 35(2023), No. 11, art. No. 2210243.

[31] B.X. Zhai, J. Gong, L.P. Liu, X.M. Cui, and Y. He, Cation (Cr³⁺, Zn²⁺, Cu²⁺ and Mn³⁺) doping to construct high entropy spinel oxide nanocrystals for modulation of oxygen evolution reaction, Fuel, 393(2025), art. No. 134992.

[32] S.I. Daradkeh, M.M. Allaham, T. Spusta, et al., Temperature-dependent evolution of electronic structure and ferrimagnetic properties in high-entropy oxide (Cr, Mn, Fe, Co, Ni)₃O₄, J. Alloy. Compd., 1031(2025), art. No. 180922.

[33] Alves RF, Raimundo RA, Lima BASG, et al.The effect of particle size on structural and catalysts for oxygen evolution reaction of (CoFeNiMnCr)₃O₄ prepared by controlled synthesis with polyvinylpyrrolidone (PVP). J. Colloid Interface Sci., 2025, 680: 818.

[34] Sharma N, Mandal S, Marik S. Structure, Raman spectroscopy, and magnetic properties of new Al, Ga, and Mn-based high entropy oxides. Ceram. Int., 2024, 50(22):48200.

[35] S. Mandal, J. Sharma, T. Chakraborty, S.K. Mahatha, and S. Marik, Structural, magnetic and X-ray absorption spectroscopy studies of new Cr-based low, medium and high-entropy spinel oxides, J. Alloy. Compd., 1010(2025), art. No. 177993.

[36] Mishra RK, Araújo EB, Shahi RR. Studies on synthesis, Raman, and electrical properties of novel spinel high entropy ceramics. J. Electroceram., 2025, 53: 18.

[37] Wang Y, Han Y, Suo WR, et al.Transition-metal oxides with peak oxygen vacancy content for oxygen electrocatalysis. Sci. China Mater., 2023, 66(11):4357.

[38] M.R. Li, W. Li, Y.X. Wang, et al., Entropy-driven microwave absorption enhancement in hexagonal (Ba_1/3Sr_1/3Ca_1/3)FeO₃ perovskite, J. Adv. Ceram., 14(2025), No. 4, art. No. 9221059.

[39] Y.L. Xu, Q. Fu, S.J. Lei, et al., Preparation of quinary CuNi_xZn_2−xInS₄ nanocrystals with wurtzite structure and tunable band gap, J. Alloy. Compd., 820(2020), art. No. 153436.

[40] Q.F. Wan, F.M. Zhang, and Y.F. Xiong, High-entropy engineering enables spinel oxides toward high-performance infrared radiation materials, Chem. Eng. J., 506(2025), art. No. 160248.

[41] Duan CQ, Tian KH, Li XL, et al.New spinel high-entropy oxides (FeCoNiCrMnXLi)₃O₄ (X = Cu, Mg, Zn) as the anode material for lithium-ion batteries. Ceram. Int., 2021, 47(22):32025.

[42] Z.Q. Xu, J. Huang, Z.X. Liu, Z.Y. Chen, and G.M. Yuan, Magnetic nanoparticles deposition based on the peculiar pore structure of nanocellulose: Preparation and properties of efficient thin-layer wave-absorbing materials, Carbohydr. Polym., 362(2025), art. No. 123679.

[43] Gupta AK, Kumari P, Prakash A, Giri NK, Shahi RR. Synthesis, characterizations, and magnetic behavior of novel (CuNiTiZnFe)₃O₄ high entropy spinel oxide. Ceram. Int., 2022, 48(24):36258.

[44] Huo YY, Wang ZY, Zhang YL, Wang YZ. High-entropy ferrite with tunable magnetic properties for excellent microwave absorption. Int. J. Miner. Metall. Mater., 2025, 32(3):668.

[45] Y.X. Guo, X.X. Zhang, H.H. Wei, H.T. Yu, and Y. Xie, Construction of spinel (Fe_0.2Co_0.2Ni_0.2Cr_0.2M_0.2)₃O₄ (M = Mg, Mn, Zn, and Cu) high-entropy oxides with tunable valance states for oxygen evolution reaction, J. Alloy. Compd., 989(2024), art. No. 174304.

[46] M.S. Patil, A.D. Sheikh, R.S. Devan, and K.K.K. Sharma, Annealing designed ZnFe₂O₄: Interplay of cationic inversion and catalytic reactions in efficient dye degradation, Inorg. Chem. Commun., 180(2025), art. No. 115088.

[47] Y.H. Bai, Z.L. Yao, Y. Yang, et al., Joule heating-driven ultra-fast synthesis of (Fe_1−xMn_x)₂AlB₂ and its electromagnetic wave absorption properties, J. Adv. Ceram., 14(2025), No. 4, art. No. 9221057.

[48] X.Y. Zhou, J. Wang, L.L. Zhou, Y.G. Wang, and D.S. Yao, Structure, magnetic and microwave absorption properties of NiZnMn ferrite ceramics, J. Magn. Magn. Mater., 534(2021), art. No. 168043.

[49] Yan Z, Luo JH. Effects of Ce–Zn co-substitution on structure, magnetic and microwave absorption properties of nickel ferrite nanoparticles. J. Alloy. Compd., 2017, 695: 1185.

[50] Qian K, Yao ZJ, Lin HY, et al.The influence of Nd substitution in Ni–Zn ferrites for the improved microwave absorption properties. Ceram. Int., 2020, 46(1):227.

[51] Du JL, Bao S, Li W, Chen YQ, Fan BB. Structural, thermal, magnetic and microwave-absorbing properties of spinel-structured high entropy oxide (MnFeCoNiX)₃O₄ (X = Zn, Cu, Cr). Ceram. Int., 2024, 50(9):14697.

[52] F.H. Mohammadabadi, S.M. Masoudpanah, S. Alamolhoda, and H.R. Koohdar, High-performance microwave absorbers based on (CoNiCuZn)_1−xMn;_xFe₂O₄ spinel ferrites, J. Alloy. Compd., 909(2022), art. No. 164637.

[53] Dai GH, Deng RX, You X, Zhang T, Yu Y, Song LX. Entropy-driven phase regulation of high-entropy transition metal oxide and its enhanced high-temperature microwave absorption by in-situ dual phases. J. Mater. Sci. Technol., 2022, 116: 11.

[54] B.Q. Wang, Y. Xu, Q.H. Shi, et al., FeCoNiTiNd/MWCNTs composite for L-band applications: Integrated thin-layer strong absorption and corrosion resistance, Carbon, 24722026), art. No. 120984.

[55] J. Guo, Y.K. Sun, X. Li, et al., Hollow core-shell structured Fe₃O₄@Polypyrrole composites for enhanced electromagnetic wave absorption, Compos. Sci. Technol., 258(2024), art. No. 110917.

[56] Gao CG, Sun XL, Chen J, et al.SiBCN-rGO ceramic fibers based on wet spinning technology: Microstructure, mechanical and microwave-absorbing properties. J. Inorg. Mater., 2025, 40(3):290.

[57] H.Y. Ding, Y.J. Yang, H. Li, Z.Y. Zhang, and Z.H. Geng, Broadband microwave absorption enhancement in FeCoNiCrMn HEAs through optimal MgO incorporation, J. Alloy. Compd., 1038(2025), art. No. 182759.

[58] Zhang WM, Zhao B, Xiang HM, Dai FZ, Wu SJ, Zhou YC. One- step synthesis and electromagnetic absorption properties of high entropy rare earth hexaborides (HE REB6) and high entropy rare earth hexaborides/borates (HE REB₆/HE REBO₃) composite powders. J. Adv. Ceram., 2021, 10(1):62.

[59] Gao ZG, Yang K, Zhao ZH, et al.Design principles in MOF-derived electromagnetic wave absorption materials: Review and perspective. Int. J. Miner. Metall. Mater., 2023, 30(3):405.

[60] Y.F. Yan, G.Y. Qin, K.L. Zhang, et al., Enhancing microwave absorption performance of MoS₂ by synergistic effect of Fe doping, J. Adv. Ceram., 14(2025), No. 3, art. No. 9221039.

[61] X.F. Zhou, Z.R. Jia, X.X. Zhang, et al., Electromagnetic wave absorption performance of NiCo₂X₄ (X = O, S, Se, Te) spinel structures, Chem. Eng. J., 420(2021), art. No. 129907.

[62] Basfer NM, Almaghamsi H. Magnetic, dielectric and electrical modulus of Ce³⁺ doped cobalt-magnesium ferrite nanoparticles. J. Rare Earths, 2024, 42(2):373.

[63] J.H. Li, K.K. Cheepurupalli, N.J. English, S. Bandaru, and X.F. Zhang, Unraveling cation distribution and defect roles in substituted ferrite performance: An atomistic DFT study, J. Appl. Phys., 138(2025), No. 12, art. No. 125001.

[64] Yadav RS, Kuritka I. Recent developments on nanocomposites based on spinel ferrite and carbon nanotubes for applications in electromagnetic interference shielding and microwave absorption. Crit. Rev. Solid State Mater. Sci., 2024, 49(3):371.

[65] Wu ZH, Deng Y, Meng ZZ, Zhang GL, Zhang LP, Wang YB. Microwave absorbing properties of novel SiC/C_f composites containing SiC array modified coating. J. Inorg. Mater., 2021, 36(3):306.

[66] Zeng BL, Zhang FR, Zhao KH, et al.Multilayered heterostructures and multicomponent synergy in MnO@HsGDY@NC/Ni magnetic nanofibers for enhanced electromagnetic wave absorption. J. Mater. Sci. Technol., 2026, 251: 193.

[67] B.S. Lei, G. Wang, C.Y. Li, et al., Rapid synthesis and enhanced microwave absorption of carbon-supported high-entropy metal oxide, J. Alloy. Compd., 1010(2025), art. No. 176964.

[68] Hu PT, Xu JR, Dong S, et al.Compositional and structural engineering of multicomponent borides hollow microspheres with superior microwave absorption performance. J. Mater. Sci. Technol., 2026, 247: 81.

[69] Zhu ZW, Feng R, Liu Y, Zhang Y, Xie WH, Dong LJ. Preparation and property of CoFe₂O₄ nanofibers with fishbonelike structure. J. Inorg. Mater., 2020, 35(9):1011.

[70] M. Kaur and S. Bahel, Characterization of sol–gel synthesized Zn_0.25Co_0.75(NiZr)_xFe_2−2xO₄ (0.05 ≤ x ≤ 0.25) spinel ferrites based microwave absorbers in Ka frequency band, J. Phys. Chem. Solids, 184(2024), art. No. 111671.

[71] Mao AQ, Quan F, Xiang HZ, Zhang ZG, Kuramoto K, Xia AL. Facile synthesis and ferrimagnetic property of spinel (CoCrFeMnNi)₃O₄ high- entropy oxide nanocrystalline powder. J. Mol. Struct., 2019, 1194: 11.

[72] R. Kalia, A. Chauhan, R. Jasrotia, M.F. Ijaz, K.M. Batoo, and R. Verma, Bi-doped cobalt ferrite nanoparticles for electromagnetic interference (EMI) shielding applications, J. Mater. Sci. Mater. Electron., 36(2025), art. No. 483.

[73] Guan JL, Li HM, Ren JN, et al.MOFs-derived flower-like cobalt@carbon multiscale hierarchical composites with effective microwave absorption in the low frequency range. Int. J. Miner. Metall. Mater., 2025, 32(4):954.

[74] Zhang YC, Gao ST, Zhang XZ, Ma DC, Zhu CL, He J. Structural and microwave absorption properties of CoFe₂O₄/residual carbon composites. Int. J. Miner. Metall. Mater., 2025, 32(1):221.

Rights & permissions

University of Science and Technology Beijing