Sol-gel processing and characterization of pure and metal-doped SnO2 thin films

A chloride-based inorganic sol-gel route was used for preparing pure and me tal (osmium, nickel, palladium, platinum)-doped SnO2 sol, SnCl4 was first r eacted with propanol, then the resulting compound was hydrolyzed and subseq uently mixed with solutions of the metal dopants, The obtained sols were us ed for depositing thin films by spin coating or for preparing powders by so lvent evaporation at 110 degreesC. FTIR spectroscopy and thermal analysis o f the powders revealed that chlorine still bound to tin stabilized the sol against gelation by hindering the condensation reactions. Film characteriza tions showed that platinum and palladium, unlike nickel and osmium, were li kely to form nanoparticles in the SnO2 lattice, This result was discussed w ith regard to the different ways that platinum and palladium, on one hand, and nickel and osmium, on the other, modified the growth of SnO2 grains and the film roughness and morphology, Dopants that formed nanoparticles (plat inum, palladium) resulted in the roughest film, while dopants that did not form particles (nickel, osmium) resulted in SnO2 grain size very close to t hat of pure SnO2.