Spin-glass behaviour of Zn/sup 57/Fe/sub 2/O/sub 4/ nanoparticles dispersed in a ZnO matrix

Summary form only given. Magnetic nanoparticles dispersed in a nonmagnetic matrix were prepared. The X-ray diffraction pattern of the resulting Zn/sub 0.99/(/sup 57/Fe/sub 0.01/)O powder was indexed with the ZnO hexagonal structure, space group P6/sub 3/mc, with cell parameters a=b=3.250(1) /spl Aring/ c=5.210(1) /spl Aring/. The relative amount of ZnFe/sub 2/O/sub 4/ phase estimated from the profile analysis was 1.1/spl plusmn/0.8%, which is in the limit of X-ray detection. The refined cell parameter for the cubic (SG Fd3m) ZnFe/sub 2/O/sub 4/ phase was a=8.448(5) /spl Aring/. Room temperature Mossbauer spectra displayed values of isomer shift and quadrupole splitting characteristic of the Fe/sup 3+/ oxidation state. Magnetization curves taken at H=1 kOe showed paramagnetic-like behavior at high temperature, with a maximum at T/sub M/=17(1) K. Below this maximum, irreversible behavior develops.