Vibrational spectra of lithium ferrites:: infrared spectroscopic studies of Mn-substituted LiFe5O8

Investigations on the series of manganese-substituted lithium ferrites reveal the destructive effect of manganese ions on the ordering of Li+ cations in the spinel-type crystal lattice. A spectacular order-disorder transition with increasing substitution of Mn3+ ions has been observed with infrared spectroscopy, in the region of lattice vibrations. The preference of manganese ions for the octahedral coordination, appears to be associated with the migration of Li+ from octahedral to tetrahedral positions. Results for the LiFe5-yMnyO8 solid solution have been confronted with an order-disorder transition in the pure lithium ferrite. (C) 2001 Elsevier Science Ltd. All rights reserved.