PARTICLE-SIZE EFFECTS ON THE VALUE OF T(C) OF MNFE2O4 - EVIDENCE FOR FINITE-SIZE-SCALING

Fe-57 Mossbauer measurements show that the T(c) of [12]-nm particles of MnFe2O4 is higher than that of the [33]-nm particles, which exhibit the bulk T(c) value (573 K). The Fe-57 isomer shift as well as the internal field are, however, independent of the particle size, as is the cation distribution determined by Mn and Fe extended x-ray absorption fine structure and Mn x-ray absorption near-edge structure measurements at different temperatures. The results confirm that the higher T(c) of the [12]-nm particles arises from finite-size scaling.