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Magnetic Properties of Barium Ferrite Formed by Crystallization of a Glass
Author(s) -
SHIRK B. T.,
BUESSEM W. R.
Publication year - 1970
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.1151-2916.1970.tb12069.x
Subject(s) - barium ferrite , superparamagnetism , coercivity , materials science , spin glass , crystallization , single domain , analytical chemistry (journal) , antiferromagnetism , condensed matter physics , nuclear magnetic resonance , magnetic domain , thermodynamics , ferrite (magnet) , chemistry , magnetization , composite material , magnetic field , physics , chromatography , quantum mechanics
A glass with composition 0.265 B 2 O 3 ‐0.405 BaO‐0.33 Fe 2 O 3 (mole ratio) was prepared by a fast‐quenching technique. When it is heat‐treated, this glass exsolves up to ∼45 wt% BaFe 12 O 19 as the only magnetic phase. Magnetic measurements of glasses heated at various temperatures show that superparamagnetic, single‐domain, or multidomain magnetic behavior is present, depending on the thermal history. The volume of a typical superparamagnetic particle (calculated from the magnetic data) is equivalent to that of a sphere 47 Å in diameter. The intrinsic coercive forces of two heat‐treated glasses were independent of temperature at high levels of H ci (2600 and 2900 Oe) from 77° to 300°K. Another heat‐treated glass has an H ci of 5350 Oe at 300°K. Apparently, the coherent rotation model of Stoner and Wohlfarth describes the magnetic behavior of BaFe 12 O 19 very well. The single‐domain critical size for BaFe 12 O 19 was ∼0.5 μm. An attractive feature of this system is that the BaFe 12 O 19 powder can be recovered from the barium‐borate‐rich matrix by leaching with a weak acid.