Utilization of strontium added NiAl2O4 composites for the detection of methanol vapors

Strontium added NiAl2O4 composites prepared by sol-gel technique was utilized for the detection of methanol vapors. X-ray diffraction, scanning electron microscopy (SEM), FT-IR spectroscopy and nitrogen adsorption/desorption isotherm at 77 K was employed respectively to identify the structural phases, surface morphology, vibrational stretching frequencies and BET surface area of the composites. The composites were prepared with the molar ratios of Ni:Sr as (1.0:0.0, 0.8:0.2, 0.6:0.4, 0.4:0.6, 0.2:0.8, 0.0:1.0) keeping the aluminum molar ratio as constant for all the compositions and were labeled as NiSA1, NiSA2, NiSA3, NiSA4, NiSA5 and NiSA6, respectively. The samples sintered at 900 °C for 5 h were subjected to dc resistance measurements in the temperature range of 30-250 °C to study the methanol vapor detection characteristics. The results revealed that the sensitivity in detecting methanol vapor increased with increase in temperature up to 175 °C for the composites NiSA1 and NiSA6 while for the other composites up to 150 °C and thereafter decreased. The sensitivity increased with increase in methanol concentration from 100 to 5000 ppm at 150 °C. Among the different composites NiSA5 showed the best sensitivity to methanol detection at an operating temperature of 150 °C.