Low Temperature Heat Capacity of Zn Substituted Cobalt Ferrite Nanosphere: The Relation between Magnetic Properties and Microstructure

Co( 1− x )Zn x Fe 2 O 4 nanospheres ( x = 0, 0.5, 0.8) with a unidirectional cubic spinel structure were prepared by a solvothermal method. By using a range of theoretical and empirical models, the experimental heat capacity values were fitted as a function of temperature over a suitable temperature range to explain the possible relationship between the magnetic properties and microstructure of the nanospheres. As a result, at a low temperature ( T < 10 K), the parameter B fsw decreases with increasing Zn concentration, implying that the exchange interaction between A and B sites decreases. At a relatively high temperature ( T > 50 K), the Debye temperature decreases with increasing Zn concentration, which is due to the weakening of the interatomic bonding force after the addition of non-magnetic materials to the CoFe 2 O 4 spinel ferrite.