Zn-doped and undoped SnO2 nanoparticles: A comparative structural, optical and LPG sensing properties study

SnO2 nanoparticles were prepared by the co-precipitation method with SnCl4·5H2O as the starting material and Zn(CH3COO)2·2H2O as the source of dopant. All the materials prepared have been found to be polycrystalline SnO2 possessing tetragonal rutile structure with crystallite sizes in the range 11–25 nm. Optical analyses reveal that for the SnO2 nanoparticles, both undoped and Zn-doped, direct transition occurs with the bandgap energies in the range 3.05–3.41 eV. Variation in the room temperature resistivity of the SnO2 nanoparticles as a function of dopant concentration has been explained on the basis of two competitive processes: (i) replacement of Sn4+ ion by an added Zn2+ ion, and (ii) ionic compensation of Zn2+ by the formation of oxygen vacancies. Among all the samples examined for LPG sensing, the 1 at% Zn-doped sample exhibits fast and maximum response (∼87%) at 300 °C for 1 vol% concentration of LPG in air.