This paper reports infrared spectroscopic studies on GdBaCo2O5.5
layered perovskite which exhibits successive magnetic transitions from
paramagnetic to ferromagnetic to antiferromagnetic states as well as high
temperature metal to insulator transition and a change in charge transport
mechanism at low temperature. Infrared absorption spectra recorded at various
temperatures in the range 80 K to 350 K reveal changes in the positions of Co-O
stretching and bending frequencies which provide an explanation to the magnetic
and transport behaviour of this compound.Comment: 5 figure