Synthesis and Structural and Magnetic Characterization of BaZn x Fe12−x O19 Hexaferrite: Hyperfine Interactions

To study the effect of Zn substitution on structural magnetic properties and hyperfine interactions of barium hexaferrite, BaFe12-x Zn (x) O-19 (0.0aexae0.3) hexaferrites were synthesized via sol-gel auto-combustion technique. Rietveld analysis of XRD powder patterns confirmed the formation of single-phase hexaferrites for all products. Due to the larger ionic size of Zn2+ as compared with Fe3+, while x increases, the lattice constant parameters increase to a small degree. Nanoplate morphology of the products is presented by SEM analyses. It was observed that both saturation magnetization and coercivity decrease in almost the same manner with zinc concentration for all substitutions. Cation distribution calculations showed that Zn2+ occupies 12k, 4 f (2), 4 f (1), and 2b sites and at the same time pushes Fe3+ ions towards 2a and 12 k (1) sites. From(57)Fe Mossbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting, and hyperfine magnetic field values on Zn2+ substitution have been determined

Impact of Tm³⁺ and Tb³⁺ rare earth cations substitution on the structure and magnetic parameters of Co-Ni nanospinel ferrite

Tm-Tb co-substituted Co-Ni nanospinel ferrites (NSFs) as (Co0.5Ni0.5) [TmxTbxFe2−2x]O4 (x = 0.00–0.05) NSFs were attained via the ultrasound irradiation technique. The phase identification and morphologies of the NSFs were explored using X-rays diffraction (XRD), selected area electron diffraction (SAED), and transmission and scanning electronic microscopes (TEM and SEM). The magnetization measurements against the applied magnetic field (M-H) were made at 300 and 10 K with a vibrating sample magnetometer (VSM). The various prepared nanoparticles revealed a ferrimagnetic character at both 300 and 10 K. The saturation magnetization (Ms), the remanence (Mr), and magneton number (nB) were found to decrease upon the Tb-Tm substitution effect. On the other hand, the coercivity (Hc) was found to diminish with increasing x up to 0.03 and then begins to increase with further rising Tb-Tm content. The Hc values are in the range of 346.7–441.7 Oe at 300 K to 4044.4–5378.7 Oe at 10 K. The variations in magnetic parameters were described based on redistribution of cations, crystallites and/or grains size, canting effects, surface spins effects, super-exchange interaction strength, etc. The observed magnetic results indicated that the synthesized (Co0.5Ni0.5)[TmxTbxFe2−x]O4 NSFs could be considered as promising candidates to be used for room temperature magnetic applications and magnetic recording media

Synthesis and Characterization of Cu–Mn Substituted SrFe12O19 Hexaferrites

In this study, bimetallic (Cu-Mn) substituted SrFe12O19 hexaferrites [Sr1-2xMnxCuxFe12O19 (0.0 <= x <= 0.1)] were synthesized via sol-gel auto-combustion approach. The effect of bimetallic substitution on structure, morphology and magnetism of SrFe12O19 was investigated. SEM images divulge the nano-size of the prepared products with speck morphology. X-ray powder diffraction analysis affirmed their complete conversion to SrFe12O19 hexagonal crystal phase. The results from Fe-57 Mossbauer suggested that all five important sextets of Sr1-2xMnxCuxFe12O19 hexaferrites effected due to the substitution of Cu and Mn ions. Cation distribution calculation showed that as the percentage of Mn and Cu increased in Sr1-2xMnxCuxFe12O19 (0.0 <= x <= 0.1), particularly for x = 0.03 the relative area of 12k and 4f(2) site increased. This indicates that Fe ions are migrated towards 12k and 4f(2) octahedral site