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Thick film microsensors based on nanosized titania sol-gel powder

Carotta M. C., Butturi M. A., Martinelli G., Di Vona M. L., Licoccia S., Traversa E.

Electron Technology

2000

Vol. 33, No. 1/2

113-117

Thick films of nanostructured TiO₂ and tantalum-doped TiO₂ have based fabricated by screen-printing technology starting from pure titania and tantalum-doped titania powders prepared by sol-gel method. The titania powders, obtained via sol-gel, show crystalline anatase structure and the particles are homogeneous and nanosized (30 ÷ 50 nm). Two series of films each one composed by pure and Ta-doped titania samples have been obtained by firing the pastes in air atmosphere at the temperatures of 650°C and 850°C, respectively. SEM observations and electrical characterizations showed that the firing temperature strongly influences the nanostructure and the gas response of the pure titania samples. The addition of tantalum inhibits the grain sintering at the higher temperature. Moreover the electrical data show that the tantalum addition (10 at.%) does not affect the conductance of the films in air while significantly enhances the response towards CO and leaves almost unaltered or enhances its ability to sense NO₂ depending on the thermal treatments.

Physics and technology of thick film sensors and thier applications for environmental gas monitoring

Martinelli G., Carotta M. C., Malagu C.

Electron Technology

2000

Vol. 33, No. 1/2

40-44

Nanostructured thick film gas sensor based on semiconducting oxides appears as an excellent candidate for a large--scale distribution of environmental detection points. In this paper we show that semiconducting oxides-based thick film gas sensors exhibit adequate properties for atmospheric environmental monitoring provided that the physical and microstructural properties of the materials are properly correlated to the required electrical features. To demonstrate the possibility of using semiconducting thick film gas sensors for the atmosphetic environmental monitoring, the sensors were tested in laboratory and in the field. They have been placed in an array inserted in a self-consistent unit and exposed to real atmosphere beside a conventional station of environmental monitoring nearby a cross light in Ferrara. The conventional monitoring station is controlled by ARPA (Regional Agency for Environmental Prevention) - Section of Ferrara. The electrical response of the thick films based on TiO₂ and Nb doped TiO₂ has been compared with the concentrations of CO in the atmosphere, as measured by the analytical equipments with the methods approved by the international standards.