LAUSR

Abstract Transition-metal-doped SnO2 quantum dots were synthesized by chemical co-precipitation technique and investigated experimentally. The dots have the chemical composition Sn1-xTxO2, where T = Cr, Mn, Fe, Co, and Ni (x = 0.02 and 0.04), and were capped by polyvinylpyrrolidone. X-ray diffraction analysis has confirmed an impurity-phase-free rutile structure of the samples and the size of the synthesized particles is of the order of 2.5 nm which is supported by the transmission electron micrograph. The fluorescence spectra of the samples confirm a strong blue shift in the near band edge (excitonic) emission peak. We also found emissions from surface localized excitons, tin atoms related defects and oxygen vacancies. The room-temperature M-H loops of the samples does not saturate in magnetic fields of up to 5 T. The magnetic data of the samples were explained on the basis of spin-flop transitions in uncompensated anti-ferromagnets.