Recently, great attention has been paid to nanostructures solid solutions based on metal oxides to enhance sensing performance with respect to those of single-oxide counterparts. 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. They would easily form solid solutions since they can exhibit a rutile type structure where octahedrally coordinated Ti4+ and Sn4+ have similar ionic radii. Such solid solution combines the positive qualities of the singles oxides, e.g. high sensitivity towards reducing gases and low influence by humidity [1,2]. Despite the good sensing performances of Sn1-xTixO2, a further improvement has been attempted by means of an Nb doping. The incorporation of Nb5+ would increase the conductivity of the material, as niobium acts as donor dopant in n-type semiconductors, and inhibit grain growth [3]. (Sn,Ti,Nb)xO2 powders were synthetized through co-precipitation by keeping the Sn/Ti proportion constant at the optimal value for sensing performance, while changing Nb concentrations and calcination temperature. Powder compositions, structures and morphologies were investigated by different techniques. Observations at SEM microscopy revealed that the morphology consists of rounded nanoparticles (Fig.1) and X-ray powder diffraction analyses confirm that (Sn,Ti,Nb)xO2 samples were a rutile-type solid solution of tin, titanium and niobium. Electrical characterization of the films showed that the niobium concentration and the heating treatment of powders are fundamental parameters to optimise the sensing characteristics of the chemiresistive film in terms of sensibility (Fig.2) and selectivity. [1] C. Malagù, V. Guidi, M.C. Carotta, G. Martinelli, Appl. Phys. Lett. 84, (2004) 4158 [2] M.C. Carotta, et al., Sensors and Actuators B 139 (2009) 329–339 [3] Ferroni, M., et al. Sensors and Actuators B: Chemical 68.1-3 (2000) 140-145
Design of a Nanostructured Metal-Oxide Solid Solution for Gas Sensing Applications
Matteo Ardit;Vincenzo Guidi
2022
Abstract
Recently, great attention has been paid to nanostructures solid solutions based on metal oxides to enhance sensing performance with respect to those of single-oxide counterparts. 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. They would easily form solid solutions since they can exhibit a rutile type structure where octahedrally coordinated Ti4+ and Sn4+ have similar ionic radii. Such solid solution combines the positive qualities of the singles oxides, e.g. high sensitivity towards reducing gases and low influence by humidity [1,2]. Despite the good sensing performances of Sn1-xTixO2, a further improvement has been attempted by means of an Nb doping. The incorporation of Nb5+ would increase the conductivity of the material, as niobium acts as donor dopant in n-type semiconductors, and inhibit grain growth [3]. (Sn,Ti,Nb)xO2 powders were synthetized through co-precipitation by keeping the Sn/Ti proportion constant at the optimal value for sensing performance, while changing Nb concentrations and calcination temperature. Powder compositions, structures and morphologies were investigated by different techniques. Observations at SEM microscopy revealed that the morphology consists of rounded nanoparticles (Fig.1) and X-ray powder diffraction analyses confirm that (Sn,Ti,Nb)xO2 samples were a rutile-type solid solution of tin, titanium and niobium. Electrical characterization of the films showed that the niobium concentration and the heating treatment of powders are fundamental parameters to optimise the sensing characteristics of the chemiresistive film in terms of sensibility (Fig.2) and selectivity. [1] C. Malagù, V. Guidi, M.C. Carotta, G. Martinelli, Appl. Phys. Lett. 84, (2004) 4158 [2] M.C. Carotta, et al., Sensors and Actuators B 139 (2009) 329–339 [3] Ferroni, M., et al. Sensors and Actuators B: Chemical 68.1-3 (2000) 140-145
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