Cation distribution in nanosized Ni-Zn ferrites

摘要

Nanoparticles of Ni_(1-x)Zn_(x)Fe_(2)O_(4) (x=0.0, 0.25, 0.50, 0.75, and 1.0) in the size range of 6-12 nm have been synthesized by chemical precipitation followed by hydrothermal treatment. A strong correlation between the particle size and the zinc concentration has been identified. Mossbauer studies on these systems show that the cation distribution not only depends on the particle size but also on the preparation route. There are indications that in the present nanophase samples Fe occupies more tetrahedral sites as compared to the normal occupancy in the spinel ferrite structure. The occupancy returns to normal values after heat treatment at 1000℃. Low-temperature Mossbauer studies indicate a significant amount of deviation of cation distribution from their bulk preferences.