Enhanced humidity sensing performance of Samarium doped Lanthanum Aluminate at room temperature

In the present research, the enhanced room temperature operable humidity sensing response of lanthanum aluminate (LA) and (1 mol%) Sm3+ doped Lanthanum aluminate (SDLA) compound synthesized by solution combustion method using in-toxic and bio-degradable sucrose (C12H22O11) as fuel, is been discussed. Structural analysis are carried out by many analytical methods like X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier Transform infrared (FTIR) spectroscopy. The crystallite size for the compound is about 40-60 nm as depicted by XRD studies, the SEM images and BET studies show increased porosity and specific surface area correlated with the decreased crystallite size of SDLA compared to LA. Intensified agglomeration forming the greater pores available for sensing further confirmed by Transmission electron microscopy (TEM) images. The shifting in absorption bands at tetrahedral and octahedral sites is confirmed by FTIR spectra. SDLA has shown maximum sensing response of 92 % in the relative humidity (RH) range 11%-97%. The response time for the compound was found to be 40s and 60 s and the stability was tested for 3 months. The mechanism of humidity sensing is schematically represented using various steps of adsorption processes. (C) 2020 Elsevier B.V. All rights reserved.