  119Sn nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation
rate (1/T1) in SnO2 nanoparticles were measured as a function of temperature
and compared with those of SnO2 bulk sample. A 15% loss of 119Sn NMR signal
intensity for the nano sample compared to the bulk sample was observed. This is
indicative of ferromagnetism from a small fraction of the sample. Another major
finding is that the recovery of the 119Sn longitudinal nuclear magnetization in
the nano sample follows a stretched exponential behavior, as opposed to that in
bulk which is exponential. Further, the 119Sn 1/T1 at room temperature is found
to be much higher for the nano sample than for its bulk counterpart. These
results indicate the presence of magnetic fluctuations in SnO2 nanoparticles in
contrast to the bulk (non-nano) which is diamagnetic. These local moments could
arise from surface defects in the nanoparticles.
