Abstract Partially europium (Eu) substituted Ni0.4Cu0.2Zn0.4EuxFe2-xO4 (0.0 ≤ x ≤ 0.10) nanostructured spinel ferrites (NSFs) were produced by sol-gel auto-combustion strategy. The XRD analyses verified the existence of the single-phase composition in all the investigated samples. The Mossbauer spectra were used to estimate the values of the line-width disparity, isomeric shift (IS), quadrupole splitting, and hyperfine magnetic field (HMF). The values of HMF of the A and B sites decreased with the rise in Eu substitutions. The paramagnetic contribution of the NSFs increased with the rise in Eu3+ contents. The S-parameters of the proposed NSFs were measured using co-axial method. The frequency dispersions of the permittivity and permeability were utilized to determine the reflection losses in the 1–20 GHz frequency range. The occurrences of the natural ferromagnetic resonance (NFMR) enabled substantial absorption of the electromagnetic energy ranged from 2.5 to 9.5 GHz. There was established a strong correlation between the level of chemical substitution (x) and amplitude-frequency characteristics of the studied spinel ferrites was established. Furthermore, the increase of Eu substitution strongly influenced the frequency characteristics of the NSFs. Anomalous changing of the resonant amplitude (more than 4 times) was shown. This can be explained by the appearance of indirect exchange interactions between Fe3+ (3 d5) and Eu3+ (4f6) electronic shells. Results revealed a potential for practical applications of such kinds of materials in functional radio electronic devices.

中文翻译：

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Eu3+ 离子取代对 Ni-Cu-Zn 尖晶石铁氧体结构、磁性和微波特性的影响

摘要 通过溶胶-凝胶自燃策略制备了部分铕 (Eu) 取代的 Ni0.4Cu0.2Zn0.4EuxFe2-xO4 (0.0 ≤ x ≤ 0.10) 纳米结构尖晶石铁氧体 (NSFs)。XRD 分析证实了所有研究样品中都存在单相组成。穆斯堡尔谱用于估计线宽差异、异构位移 (IS)、四极分裂和超精细磁场 (HMF) 的值。A 和 B 位点的 HMF 值随着 Eu 取代的增加而降低。NSFs 的顺磁贡献随着 Eu3+ 含量的增加而增加。所提出的 NSF 的 S 参数是使用同轴方法测量的。利用介电常数和磁导率的频率色散来确定 1-20 GHz 频率范围内的反射损耗。自然铁磁共振 (NFMR) 的出现使得能够大量吸收 2.5 至 9.5 GHz 范围内的电磁能。在化学取代水平 (x) 和所研究的尖晶石铁氧体的幅频特性之间建立了很强的相关性。此外，Eu 取代的增加强烈影响了 NSF 的频率特性。显示了共振幅度的异常变化（超过 4 次）。这可以通过 Fe3+ (3 d5) 和 Eu3+ (4f6) 电子壳之间的间接交换相互作用的出现来解释。结果揭示了此类材料在功能无线电电子设备中的实际应用潜力。