Recently, great attention has been paid to solid solutions and composite materials based on metal oxides in order to obtain nanostructures with enhanced sensing performance with respect to those of single-oxide counterparts [1]. Tin and titanium dioxides (SnO2 and TiO2) are wide-gap n-type semiconductors extensively investigated for the fabrication of solid-state devices for gas sensing applications. Albeit SnO2-based gas sensors exhibit high response to reducing gases, they suffer of poor selectivity and degradation of electrical properties at low oxygen partial pressure and high operating temperatures upon prolonged exposure to reducing gases [2]. Instead, TiO2 is more thermally stable than SnO2, but it has a lower sensitivity due to a higher density of surface states, that entails the pinning of the Fermi level [3]. SnO2 and TiO2 would easily form solid solutions because they can exhibit a rutile type structure where octahedrally coordinated Ti4+ and Sn4+ have similar ionic radii (i.e. 0.605 Å and 0.69 Å, respectively) [4,5]. In an earlier investigation, the sensing properties of Sn1-x TixO2 (0.2<0.7) oxides prepared through sol-gel route from stoichiometric solutions of the two metal-alkoxides have been explored [6]. Sn1-xTixO2 solid solution showed better sensing performances than SnO2 and TiO2 under different target gases, with the Sn0.7Ti0.3O2 solid solution overperforming with respect to the other investigated compounds [6]. Despite the Sn1-xTixO2 good sensing performances, a further improvement on the sensing aptitude of these materials has been attempted by means of a Nb doping. The incorporation of Nb5+ within the Sn0.7Ti0.3O2 lattice would increase the conductivity of the material, as niobium acts as donor dopant in n-type semiconductors and it can inhibit grain growth [7].
(Sn,Ti,Nb)xO2 Solid Solution: An Innovative Nanostructured Material and Its Chemoresistive Properties
Andrea Gaiardo;Matteo Valt;
2021-01-01
Abstract
Recently, great attention has been paid to solid solutions and composite materials based on metal oxides in order to obtain nanostructures with enhanced sensing performance with respect to those of single-oxide counterparts [1]. Tin and titanium dioxides (SnO2 and TiO2) are wide-gap n-type semiconductors extensively investigated for the fabrication of solid-state devices for gas sensing applications. Albeit SnO2-based gas sensors exhibit high response to reducing gases, they suffer of poor selectivity and degradation of electrical properties at low oxygen partial pressure and high operating temperatures upon prolonged exposure to reducing gases [2]. Instead, TiO2 is more thermally stable than SnO2, but it has a lower sensitivity due to a higher density of surface states, that entails the pinning of the Fermi level [3]. SnO2 and TiO2 would easily form solid solutions because they can exhibit a rutile type structure where octahedrally coordinated Ti4+ and Sn4+ have similar ionic radii (i.e. 0.605 Å and 0.69 Å, respectively) [4,5]. In an earlier investigation, the sensing properties of Sn1-x TixO2 (0.2<0.7) oxides prepared through sol-gel route from stoichiometric solutions of the two metal-alkoxides have been explored [6]. Sn1-xTixO2 solid solution showed better sensing performances than SnO2 and TiO2 under different target gases, with the Sn0.7Ti0.3O2 solid solution overperforming with respect to the other investigated compounds [6]. Despite the Sn1-xTixO2 good sensing performances, a further improvement on the sensing aptitude of these materials has been attempted by means of a Nb doping. The incorporation of Nb5+ within the Sn0.7Ti0.3O2 lattice would increase the conductivity of the material, as niobium acts as donor dopant in n-type semiconductors and it can inhibit grain growth [7].I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
