Room temperature ferromagnetism in Th1-xFexO2-δ (x = 0.0, 0.05, 0.10, 0.15, 0.20 and 0.25) nanoparticles

Nanocrystalline (Th1-xFex)O2-δ particles with different Fe concentrations (x = 0.0, 0.05, 0.10, 0.15, 0.20 and 0.25) have been prepared by a gel combustion method. Rietveld refinement analyses of X-ray diffraction data revealed the formation of an impurity free cubic type Th1-xFexO2-δ structure up to x = 0.20. This observation is further confirmed from the detailed studies conducted on 10 at.% Fe doped ThO2 using high-resolution transmission electron microscopy (HRTEM) imaging and indexing of the selected-area electron diffraction (SAED) patterns. DC magnetization studies as a function field indicate that they are ferromagnetic with Curie temperature (Tc) well above room temperature