Synthesis of nanocrystalline Ni1-xCoxMnxFe2-xO4:: a material for liquefied petroleum gas sensing

Nanocrystalline nickel ferrites doped with cobalt and manganese, having an average crystallite size of 10-15 nm and surface area of 5060 m(2)/g, were synthesized by the hydrazine method and studied for gas sensing behavior to reducing gases like liquefied petroleum gas (LPG), Ethanol, CO and CH4. Powder X-ray diffraction, differential thermal analysis (DTA), Brunauer-Emmett-Teller (BET) surface area, Fr-IR, scanning electron microscopy and energy dispersive X-ray analysis (EDXA) were employed to characterize the composition, phase and particle size of these ferrites. It is observed that the gas sensitivity largely depends on the composition, crystallite size/surface area and the test gases to be detected. Incorporation of 1 wt.% I'd improved the sensitivity, selectivity, response time and reduced the operating temperature of the sensor for LPG. The response time for 1000 ppm LPG is less than 1 min at 180 degreesC. A mechanism supported by the LPG interaction with the ferrite has been proposed on the basis of FT-IR studies. (C) 2002 Elsevier Science B.V. All rights reserved.