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Structural and Chemical Alterations of Delta Fe 2 O 3 and Their Effect on Magnetic Properties
Author(s) -
CONLEY ROBERT F.
Publication year - 1967
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.1151-2916.1967.tb15060.x
Subject(s) - ferrimagnetism , nucleation , remanence , particle size , crystal structure , materials science , thermal stability , precipitation , ultrafine particle , chemical engineering , oxide , iron oxide , crystallography , mineralogy , chemistry , metallurgy , nanotechnology , magnetization , magnetic field , organic chemistry , physics , quantum mechanics , meteorology , engineering
The defect structure, δ‐Fe 2 O 3 , was grown epitaxially with ultrafine, activated Al 2 Si 2 O 5 (OH) 4 . More uniform particle size and consistent structure result with this process than with auto‐nucleation. The low ferrimagnetic character is influenced by precipitation parameters. Magnetic properties and crystal order can be promoted by a novel thermal conversion process using a high‐boiling aliphatic hydrocarbon. The process induces the formation of a more complex iron oxide. A structure is believed to form of an order higher than δ‐Fe 2 O 3 but lower than γ‐Fe 2 O 3 . Analyses (C, H, CO 2 , and H 2 O) are correlated with magnetic properties. Specimens having a mean particle size of 20 mμ were produced with coercivities up to 290 oe and remanent inductions up to 1800 gauss/cm 3 . Stability tests over a five‐year period showed no degradation.