Heat capacity investigation of dopant effects on the magnetic disordering temperature in Fe3O4

Abstract The heat capacities of ZnFe 2 O 4 , Zn 0.005 Fe 2.995 O 4 , Zn 0.066 Fe 2.934 O 4 , and Cd 0.010 Fe 2.990 O 4 were measured over the temperature range of 350–1000 K by means of differential scanning calorimetry. The temperatures at which the maximum in heat capacity occurs due to the ferrimagnetic anomaly in the doped-Fe 3 O 4 samples were found to decrease with increasing dopant. The excess entropy associated with the ferrimagnetic anomaly was estimated using three methods. One method, used previously for Fe 3 O 4 , employed a calculated lattice contribution for Fe 3 O 4 . The other two methods used the experimentally determined heat capacity of ZnFe 2 O 4 , either unmodified or mass adjusted, to approximate contributions from lattice vibrations.