INFRARED-ABSORPTION SPECTRA OF MANGANESE OXIDES LA1-X-YRYCAXMNO3-DELTA

Infrared transmission spectra were measured systematically in polycrys talline La1-xCaxMnO3-delta and several systems substituted by other ra re earth (RE) ions such as Sm3+, Gd3+, Dy3+, etc., at La3+ sites or Fe ions at Mn sites but keeping the nominal Mn4+/Mn3+ approximate to 3/7 . Two strong absorption peaks located around 600 and 350 cm(-1), which are associated with internal phonon modes, i.e., stretching and bendi ng modes of MnO6 octahedra, have been observed. Both of them are influ enced by the concentrations of Ca and other RE ions substituting at th e La and Mn sites. The details of the absorption peaks will be discuss ed on the basis of changes of the bond length of Mn-O and bond angle o f Mn-O-Mn in MnO6 octahedra. (C) 1997 American Institute of Physics.