Multi-susceptibile Single-Phased Ceramics with Both Considerable Magnetic and Dielectric Properties by Selectively Doping

Abstract

Multiferroic ceramics with extraordinary susceptibilities coexisting are vitally important for the multi-functionality and integration of electronic devices. However, multiferroic composites, as the most potential candidates, will introduce inevitable interface deficiencies and thus dielectric loss from dissimilar phases. In this study, single-phased ferrite ceramics with considerable magnetic and dielectric performances appearing simultaneously were fabricated by doping target ions in higher valence than that of Fe3+, such as Ti4+, Nb5+ and Zr4+, into BaFe12O19. In terms of charge balance, Fe3+/Fe2+ pair dipoles are produced through the substitution of Fe3+ by high-valenced ions. The electron hopping between Fe3+ and Fe2+ ions results in colossal permittivity. Whilst the single-phased ceramics doped by target ions exhibit low dielectric loss naturally due to the diminishment of interfacial polarization and still maintain typical magnetic properties. This study provides a convenient method to attain practicable materials with both outstanding magnetic and dielectric properties, which may be of interest to integration and multi-functionality of electronic devices.

Calculation of exchange integrals and Curie temperature for La-substituted barium hexaferrites

“…Owing to the large magnetocrystalline anisotropy, high Curie temperature T c and saturation magnetization M s , barium hexaferrites [BaFe 12 O 19 , BaM] are of great interest for magnetic recording, microwave magnetic devices, and permanent magnets123. Many schemes34567 have been attempted in the past few decades to improve the intrinsic magnetic properties of barium hexaferrites.…”

Medium Modulated Oxygen Reduction Activity of Fe/Co Active Centre‐engrafted Electrocatalysts

“…[38] The results indicate the analogy with the previous reports where the pyridinic and graphitic content increase with the annealing. [39][40] The formation of Fe 2 + and Fe 3 + is observed in FeÀ N-GVC and Fe/2CoÀ N-GVC, whereas Co 2 + is present in the CoÀ N-GVC and Fe/2CoÀ N-GVC composites.…”

Formation of BaFe12−xNbxO19 and its high electromagnetic wave absorption properties in millimeter wave frequency range

“…where γ is the gyromagnetic ratio, g is Landé factor, and H a is anisotropy field. It is known that H a of barium ferrite is contributed by magnetic ions Fe 3+ in seriously deformed oxide polyhedrons, and the H a would decrease continuously with increasing Fe 3+ ions being substituted by nonmagnetic Nb 5+ ions . That is to say, the more the Fe 3+ ions are replaced by Nb 5+ ions, the lower the natural resonance peak frequency might be.…”

“…It is known that H a of barium ferrite is contributed by magnetic ions Fe 3+ in seriously deformed oxide polyhedrons, and the H a would decrease continuously with increasing Fe 3+ ions being substituted by nonmagnetic Nb 5+ ions. 9,13,14 That is to say, the more the Fe 3+ ions are replaced by Nb 5+ ions, the lower the natural resonance peak frequency might be. The decreased resonance peak frequency with Nb 5+ content and temperature improving in Figure 6 is hence ascribed to the enhanced substitution amount of Nb 5+ for Fe 3+ .…”

“…The barium hexaferrite BaFe 12 O 19 , a kind of versatile material, has been widely used as permanent magnet and high-density recording media due to its high coercive force, large saturation magnetization, and corrosion resistivity. [9][10][11][12] Lately, barium ferrite with Fe 3+ being substituted by ions with higher valence, such as Zr 4+ or Ti 4+ , has been suggested to use in high-efficiency EM absorption area owing to their multiple natural resonance peaks in permeability and large permittivity contributing broad bandwidth and thin matching thickness. 13,14 It implies that substituting Fe 3+ ions of barium ferrite by higher valence ions might be an effective way to develop absorption materials with extraordinary properties.…”