Nonstoichiometric spinel ferrites obtained from alpha-NaFeO2 via molten media reactions.
Different solid/liquid "exchange" reactions involving divalent cations, protons, or ammonium ions have been performed at low/moderate temperatures (between 80 and 500 degrees C) on alpha-NaFeO2 dipped in molten salts (or acid) media. Several ferrites have been obtained which are nonstoichiometric with partially inverse spinel structures. When sodium is replaced by divalent cations (Mg2+, Co2+, Ni2+, and Zn2+), the obtained ferrites are hyperstoichiometric (cation/oxygen ratio higher than 3/4) whereas proton or ammonium reactions result in hypostoichiometric materials (cation/oxygen lower than 3/4). All these ferrites present a platelet-like morphology and show ferrimagnetic, soft magnet behavior.
Morán
Emilio
E
Dpto. Química Inorgánica, Fac. CC. Químicas, Universidad Complutense, 28040-Madrid, Spain. emoran@ quim.ucm.es
Blesa
Ma Carmen
MC
Medina
M-Eloisa
ME
Tornero
Jesús D
JD
Menéndez
Nieves
N
Amador
Ulises
U