부산대학교 도서관

Sn1−xLaxO2 nanoparticles (x = 0, 0.001, 0.01 and 0.1) were prepared using a polyol method. X-ray diffraction patterns showed that only the tetragonal rutile phase is present for x = 0, 0.001, and 0.01. For Sn0.9La0.1O2, in addition to the tetragonal phase, a SnO impurity phase is present for x = 0.1. Fourier transform infrared spectroscopy (FTIR) measurements spotted the variation of local defects and grain size of the prepared nanoparticles. Scanning electron microscope (SEM) images revealed no variation in the microstructure of SnO2 with La doping except for x = 0.1. Ultraviolet–visible absorbance spectroscopy (UV–vis) was utilized to investigate the optical properties and the evolution of the band gap with lanthanum doping. A Brunauer-Emmett-Teller (BET) specific surface area (SSA) method was performed to determine the surface properties of the prepared samples. Vibrating-sample magnetometer (VSM) measurements revealed room temperature ferromagnetism in all the prepared samples. The electron spin resonance (ESR) response shows a clear dependence on La doping. Deep analysis of VSM and ESR results was performed in the frame of the bound magnetic polaron model to understand the origin of room temperature ferromagnetism in these compounds.