FAR INFRARED AND MICROSTRUCTURAL STUDIES OF MECHANICALLY ACTIVATED NICKEL MANGANITE

Abstract

Nickel manganite powder was mechanically activated in a high energy planetary ball mill for 5-60 min. Then the powders were pressed and sintered for 60 minutes at 9000C, 10500C and 12000C. Morphological changes of nickel manganite ceramics were monitored using scanning electron microscopy, while changes in structural characteristics were followed using X-ray diffraction. Far infrared reflectivity spectra at room temperature for all sintered samples were recorded in the frequency range between 50 and 1200 cm-1. Transversal and longitudinal optical modes were calculated for six ionic oscillators (four strong, and two shoulders) belonging to the partially inverse spinel structure of nickel manganite.