Investigation of magnetic properties for Hf4+ substituted CeO2 nanoparticles for spintronic applications

The single phase HfxCe1-xO2 (x = 0.01, 0.05 and 0.1) nanoparticles were produced via microwave refluxing technique. The substitution of Hf-ions into CeO2 lattice has been demonstrated by X-ray diffraction and transmission electron microscopy analyses. X-ray photoelectron spectroscopy analysis indicated that Ce was present in + 3 and + 4 states whereas Hf in + 4 state. Raman, UV-Vis and photoluminescence spectroscopic analyses revealed the formation of surface defects including oxygen vacancies in the samples. The estimated defect concentration was 1.09 x 10(21), 1.32 x 10(21) and 1.49 x 10(21) cm(-3) for x = 0.01, 0.05 and 0.1 samples respectively. The room temperature ferromagnetic behavior for the samples originate from the surface oxygen vacancies. The prevalence of ferromagnetic clusters considerably raised the M-S value for x = 0.05 sample. The augmentation in the M-S values with increased Hf concentration could be attributed to the increase in the defect concentration.