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Ethanol-sensing characteristics of cadmium ferrite prepared by chemical coprecipitation

Advanced Materials Research Center, Division of Materials Engineering, School of Applied Science, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore; Department of Inorganic Materials, Shanghai University, 201800 Shanghai, China; Microelectronics Centre, School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore
Materials Chemistry and Physics (Impact Factor: 2.07). 01/1999; DOI: 10.1016/S0254-0584(99)00133-9

ABSTRACT The microstructure, electrical property and gas-sensing characteristics of complex compounds in the CdO–Fe2O3 system have been investigated. Raw powder with Cd/Fe = 1 : 2 was prepared by chemical coprecipitation method. The results from thermal gravimetric-differential thermal analysis and X-ray diffraction measurement indicate that decomposition of CdCO3 takes place from 350 to 500°C, and the solid reaction in CdO–Fe2O3 system starts at 570°C; the completion of this reaction is up to 800°C. Single phase of CdFe2O4 is composed of spheroidic grains with narrow size distribution between 50 and 150 nm. Sample calcined at 650°C consists of smaller grains with different shape and sizes due to the presence of three phases, i.e., CdFe2O4, CdO and α-Fe2O3. The sensors based on Cd–Fe complex oxides show a high sensitivity and selectivity to C2H5OH gas over CO, H2 and i-C4H10. The sensor made of 650°C sample operates at 380°C, and its sensitivity to 200 ppm C2H5OH gas is up to 90, but its sensitivity to 1000 ppm H2, CO or i-C4H10 are only 7.5, 4 and 5, respectively.

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    ABSTRACT: Room temperature ferromagnetism and an increase in saturation magnetization due to Mn-doping are observed in CoFe2O4 nanoparticles. The ethanol sensitivity of undoped and Mn-doped (3 at.%) CoFe2O4 nanoparticles were experimented at ambient temperature using optical fiber based on evanescent wave adsorption phenomenon. By modifying the clad exposure to gas vapor, the sensitivities were calculated to be 0.07 and 0.12 counts/ppm for undoped and Mn-doped CoFe2O4 nanoparticles respectively, showing significant enhancement in ethanol sensitivity for Mn-doped sample.
    07/2011;
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    ABSTRACT: Present paper reports the preparation and characterization of nanorods and mixed shaped (nanospheres/nanocubes) copper ferrite for liquefied petroleum gas (LPG) sensing at room temperature. The structural, surface morphological, optical, electrical as well as LPG sensing properties of the copper ferrite were investigated. Single phase spinel structure of the CuFe2O4 was confirmed by XRD data. The minimum crystallite size of copper ferrite was found 25 nm. The stoichiometry was confirmed by elemental analysis and it revealed the presence of oxygen, iron and copper elements with 21.91, 12.39 and 65.70 atomic weight percentages in copper ferrite nanorods. The band gap of copper ferrite was 3.09 and 2.81 eV, respectively for nanospheres/nanocubes and nanorods. The sensing films were made by using screen printing technology and investigated with the exposure of LPG. Our results show that the mixed shaped CuFe2O4 had an improved sensing performance over that of the CuFe2O4 nanorods, of which a possible sensing mechanism related to a surface reaction process was discussed. Sensor based on mixed shaped copper ferrite is 92% reproducible after one month. The role of PEG in the synthesis for obtaining nanospheres/nanocubes has also been demonstrated.Highlights► Mixed shaped (nanocubes/nanospheres) and nanorods of copper ferrite were synthesized by co-precipitation method. ► The influence of surface morphology on the LPG sensing properties of copper ferrite was investigated. ► The role of PEG in the synthesis for obtaining uniform sphericals/nanocubes like surface morphology has been demonstrated. ► Mixed shaped copper ferrite shows an improved sensing performance in comparison with that of the CuFe2O4 nanorods. ► The maximum sensor response obtained with mixed shaped CuFe2O4 to LPG is 57.
    Applied Surface Science 01/2011; 257(24):10763-10770. · 2.54 Impact Factor
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    IEEE Sensors Journal 05/2012; · 1.48 Impact Factor

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