Utilization of strontium added NiAl(2)O(4) composites for the detection of methanol vapors

Strontium added NiAl(2)O(4) 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 77K 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 degrees C for 5 h were subjected to dc resistance measurements in the temperature range of 30-250 degrees 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 degrees C for the composites NiSA1 and NiSA6 while for the other composites up to 150 degrees C and thereafter decreased. The sensitivity increased with increase in methanol concentration from 100 to 5000 ppm at 150 degrees C. Among the different composites NiSA5 showed the best sensitivity to methanol detection at an operating temperature of 150 degrees C.