title: Physicochemical aspects of novel surfactantless, self-templated mesoporous SnO2 thin films.
abstract: A novel method of synthesis consisting of the production of ordered arrangements of tubular pores distributed inside SnO2 annealed thin films, which are prepared from a rotating disk process carried out at 2000-3500 rpm, is herein described. The main novelty is that no surfactant molecules are required in order to create these ordered pore structures; the templating entities are supramolecular assemblies of oligomeric chains formed during the extra-long aging allowed to the sol-gel processing of tin(IV) tetra-tert-amiloxide, Sn(OAm(t))4, chelated with acetylacetone molecules. Low angle X-ray diffraction peaks of SnO2 thin films calcined at 500 degrees C clearly certify the existence of ordered mesostructures when employing the right H2O/Sn(OAm(t))4 molar ratio during the SnO2 sol-gel synthesis. The final SnO2 ordered mesostructures are reminiscent of those linked to MCM-41 and SBA-15 substrates. Pore-size distribution analyses proceeding from N2 sorption isotherms at 76 K on the SnO2 thin films calcined at 500 degrees C unequivocally confirm the presence of tubular mesopores (mode pore sizes ranging from 5 to 7 nm). The thicknesses of the SnO2 films range from 80 to 150 nm after performing a drying process at 100 degrees C and from 70 to 125 nm after calcining in air at 500 degrees C; these film thicknesses show, in general, decreasing trends when either the spinning rate or the H2O/(Sn(OAm(t))4 ratio is increased.
authors.affiliation: Departamento de Química, Universidad Autónoma Metropolitana--Iztapalapa, P.O. Box 55-534, México, DF 09340, México.
authors.forename: Celso
authors.initials: C
authors.lastname: Velasquez
authors.forename: Fernando
authors.initials: F
authors.lastname: Rojas
authors.forename: J Marcos
authors.initials: JM
authors.lastname: Esparza
authors.forename: Armando
authors.initials: A
authors.lastname: Ortiz
authors.forename: Antonio
authors.initials: A
authors.lastname: Campero