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Rare‐Earth‐Substituted Sr 1− x Ln x Fe 12 O 19 Hexagonal Ferrites
Author(s) -
Seifert Daniela,
Töpfer Jörg,
Stadelbauer Markus,
Grössinger Roland,
Le Breton JeanMarie
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.04363.x
Subject(s) - analytical chemistry (journal) , solid solution , ferrite (magnet) , materials science , ion , crystallography , lattice constant , crystal structure , chemistry , metallurgy , diffraction , physics , organic chemistry , chromatography , optics , composite material
A systematic study on the phase formation and magnetic properties of M‐type hexagonal ferrite solid solutions Sr 1− x Ln x Fe 12 O 19 with rare‐earth ions Ln=Pr, Nd, Sm, Eu, and Gd was performed. All ferrite samples were prepared by the mixed oxide route and characterized with a combination of powder XRD, microscopy, electron‐probe microanalysis, and thermal analysis. For Ln=Pr, Nd, and Sm, the formation of M‐type ferrite solid solutions with limited solubility of rare earths was observed. The lattice parameters of Sr 1− x Ln x Fe 12 O 19 exhibit a linear variation with x within the range of ferrite solid solution, i.e., c 0 decreases with x . For Eu‐ and Gd‐containing samples substituted X‐type ferrites are observed. The solubility limits of the rare‐earth ions within the M‐type ferrite lattice range from x =0.46 for Pr to about x =0.17 for Sm. Eu and Gd can be substituted to lesser amounts in the X‐type ferrites. The saturation magnetization at T =5 K increases with increasing rare‐earth concentration for Pr, Nd, and Sm. Mössbauer spectrometry reveals signals originating from Fe 3+ on five different crystallographic positions of the M‐type structure as well as ferrous ions on Fe 2 a sites. The spectra of the hexagonal ferrites with different rare‐earth ions (La, Pr, Nd, Sm) are very similar and show systematic variations of the hyperfine fields with rare‐earth concentrations.