CO2 Gas Sensing Response of YPO4 Nanobelts Produced By a Colloidal Method

YPO₄ has been extensively studied as host lattice for luminescence materials; however, little is known about its gas sensor properties. In this work, YPO₄ was synthesized by a colloidal method using yttrium nitrate, phosphorous acid and CTAB (as surfactant). The calcination at 500ºC produced single–phase YPO₄ nanobelts, having length between 3 and 10 mm, and width between 70 and 250 nm. Impedance measurements were performed on thick films made with the as–prepared YPO₄ nanobelts. The results show repeatability for detecting 200 ppm CO₂, from 350ºC; however, the response was enhanced at 400ºC. At this temperature YPO₄ responded in a wider frequency range, from 100 Hz to 100 kHz. Quantitative detection of CO₂, in the range 200 – 800 ppm, was evaluated through a variation of the dielectric constant of the film. Preliminary results of CO sensing displayed a fast response, but also large data scattering and a long term drift were present. According to its response to CO, a p–type semiconductor behavior was noticed.