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Formaldehyde gas sensor based on silver-and-yttrium-co doped-lithium iron phosphate thin film optical waveguide

2012; Elsevier BV; Volume: 176; Linguagem: Inglês

10.1016/j.snb.2012.10.037

1873-3077

Patima Nizamidin, Abliz Yimit, Adalat Abdurrahman, Kiminori Itoh,

Spectroscopy and Laser Applications

Abstract Several formaldehyde gas sensors were fabricated using silver-and-yttrium-co doped-lithium iron phosphate (LiFe 1−0.01 x Y 0.005 x Ag 0.005 x PO 4 )-thin-film-based optical waveguides (OWGs). LiFe 1−0.01 x Y 0.005 x Ag 0.005 x PO 4 powders with different concentrations of the dopants Ag and Y were prepared in high purity via a one-step hydrothermal method, and characterized using their X-ray diffraction patterns and energy dispersion spectra. The obtained powders were subsequently utilized in a spin-coating procedure for the fabrication of LiFe 1−0.01 x Y 0.005 x Ag 0.005 x PO 4 thin films. The obtained thin films were characterized by refractive index, thickness, attenuation, and sensing properties to formaldehyde at room temperature. The response of LiFe 1−0.01 x Y 0.005 x Ag 0.005 x PO 4 -thin-film/tin-diffused-glass-based optical waveguide sensors to formaldehyde was higher than their responses to other VOCs. For a set of formaldehyde concentrations ranging from 1 ppb to 1000 ppm, the sensitivity of the sensors increased with a decrease in the dopant concentrations. Moreover, the ability to be used repeatability as well as the selectivity of the sensors was tested using lower gas concentrations; at the lower concentrations (below 250 ppm), the sensor only responsive to formaldehyde gas.