Defect assisted improved room temperature ferromagnetism in Ce doped SnO2 nanoparticles

In the present work, pure and Ce doped SnO2 have been prepared via sol-gel method and the effect of Ce doping on the structural, optical and magnetic properties of SnO2 are studied systematically. A detailed structural analysis has been carried out by X-ray diffraction (XRD), field emission scanning microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, Raman scattering, X-ray photoelectron spectroscopy (XPS). These studies reveal that pure and Ce doped SnO2 NPs have a polycrystalline single phase tetragonal rutile structure without any detectable impurity phases and most of the dopant ions occupy the lattice site into the host structure of SnO2. The core level XPS spectrum of Ce 3d reveals that most of the Ce ions are in 3+ valence state. Simulated O K-edge based soft X-ray absorption analysis, high resolution O 1s XPS results and photoluminescence study reveal that oxygen vacancies are generated in the doped samples. Band gap of SnO2 is found to decrease with increase in Ce content. Magnetic measurements show that all the Ce doped samples clearly display the room temperature ferromagnetic behavior while pure SnO2 shows diamagnetic nature. Magnetic parameters have been determined from the fitted M-H loops and transition from diamagnetic to ferromagnetic is observed when Ce ions are doped into SnO2 structure.