Influence of In doping on the structural, photo-luminescence and alcohol response characteristics of the SnO2 nanoparticles

Undoped and In-doped SnO2 nanoparticles were synthesized by the co-precipitation method. Upon In doping, the samples exhibit reduced crystallinity as compared to the undoped SnO2. The Raman spectra of the undoped samples exhibit three fundamental peaks at 467.3, 633.4 and 774.6 cm−1 corresponding to Eg, A1g and B2g vibration modes, respectively. The PL spectra show two strong emission bands at the wavelengths 417 nm and 479 nm, along with five weak emission peaks in the visible region. Alcohol response characteristics of the In-doped SnO2 samples were investigated for various concentrations (10–50 ppm) at different operating temperatures (150–250 °C). Among all the samples examined, the 3 at% In-doped SnO2 sample shows maximum response (96.5%) to propan-2-ol, followed by ethanol (92%) and methanol (90%) at the operating temperature of 250 °C for 50 ppm concentration. For each test alcohol, the response has been found to increase with the In dopant concentration.