Structural and photoluminescence properties of tin oxide and tin oxide: C core–shell and alloy nanoparticles synthesised using gas phase technique

In the present study, we report a controlled growth of tin oxide and tin oxide: carbon nanoparticles by an integrated method comprising of the gas phase agglomeration, electrical mobility based size selection, and in–flight sintering steps. The effect of in-flight sintering temperature and variation in growth environment (N2, H2 and O2) during nanoparticle formation, morphology and composition has been investigated by carrying out High Resolution Transmission Electron microscopy and X-Ray diffraction studies. The results highlight the novelty of the present technique to grow alloy and core-shell nanoparticles in which the stoichiometery (x) of SnOx and the mode of incorporation of carbon into the tin oxide lattice (alloy or core-shell structure), along with well-defined size can be controlled independently. Detailed Photoluminescence (PL) studies of well sintered monocrystalline SnO, SnOx and SnO2 nanoparticles along with SnOx:C and SnO2:C alloy and C@SnO core-shell nanoparticle has been carried out. The shift in the position and nature of PL peaks due to band edge, Sn interstitials and oxygen vacancy defect level energy states has been understood as a function of stoichiometery and nanoparticle structure (alloy and core-shell). These results suggest the possibility of tailoring the position of these levels by controlling the size, composition and alloying which is potentially important for gas sensing, photoconductivity and photo-electrochemical applications