Ferrite multiphase/carbon nanotube composites sintered by microwave sintering and spark plasma sintering

Abstract

Ni-Carbon nanotube (CNT)-Ni0.5Zn0.5Fe2O4 multiphase composites were successfully prepared using microwave sintering (MWS) and spark plasma sintering (SPS) techniques. The obtained samples were characterized by scanning electron microscopy, electrical conductivity, and physical properties measurement system with vibrating sample magnetometer. The SPS prepared composites exhibited higher density, fine grain size, and to maintain favorable three-dimensional conductive network of CNTs compared with the microwave sintered (MWS) ones. Whether use MWS or SPS, both the density and the grain size are increasing with the CNT content increment. The increasing of density and grain size is the main contribution of the saturation magnetization increasing. In the composites of high content of CNTs (such as 5 wt %), the spinel structure of ferrite was totally destroyed, as indicated by a considerable decrease in the saturation magnetization. Interestingly, it is found that the Curie temperature increases with the increment of CNT content while the high saturation magnetization was maintained, which has implication that the multiphase ferrite composites will find application in a broad temperature range.