MAGNETIC-PROPERTIES OF NICKEL FERRI ALUMINATES

The structural and magnetic properties of mixed spinel system NiAlxFe2 -xO4 (x =0.0,0.2,0.4,0.6,0.8 and 1.0) have been investigated by X-ray diffraction, magnetization, Mossbauer spectroscopy and a c susceptibil ity measurements. Magnetization and Mossbauer results for x = 0.0 to 1 .0 exhibit a collinear ferrimagnetic structure. This is further suppor ted by the fact that the decrease in Curie temperature deduced from a c susceptibility measurements is found to be linear for x less than or equal to 1.0, with increase in Al-content (x). The Curie temperatures calculated theoretically by applying modified molecular field theory are in good agreement to those determined experimentally.