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Strontium(II) Added MgAl2O4 Composites For Ammonia Detection

K.S.Nagaraja, J.Judith Vijaya, L.John Kennedy and G.Sekaran

Strontium(II) added MgAl2O4 composites prepared by sol–gel technique was utilized for the detection of ammonia vapors. XRD, SEM and BET surface area measurements were employed to identify the structural phases and surface morphology. The composites were prepared with the mole ratios of Mg: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 aluminium mole ratio as constant for all the compositions and were labeled as MgSA1, MgSA2, MgSA3, MgSA4, MgSA5 and MgSA6 respectively. The samples sintered at 900°C for 5 h were subjected to dc resistance measurements in the temperature range of 30-200°C to study the ammonia vapor detection characteristics. The results revealed that the sensitivity in detecting ammonia vapor increased with increase in temperature up to 150°C and thereafter decreased. The sensitivity increased with increase in ammonia concentration from 100- 5000 ppm at 150°C. Among the composites MgSA5 showed the best sensitivity to ammonia detection at an operating temperature of 150°C. ï›™ 2006 Trade Science Inc. - INDIA