• Dr. Rajendra R. Attarde

Abstract : Nanostructured MnO2 powders were synthesized by hydrolysis of AR grade manganese chloride in aqueous-alcohol solution with bismuth chloride (dopant in the proportion 1, 3, 5 and 7 wt %) to get fine powder. Thick films of Bi2O3-doped MnO2 powders were prepared by screen printing technique. The structural properties of these films were studied by X-ray diffraction technique. The XRD spectrum revels that the films are polycrystalline in nature and monoclinic in structure. The average grain size was determined using Scherrer’s formula and was estimated to be of 396 nm. It was also observed that, the amorphous nature decreases (i. e. crystalline nature increases) with the percentage of doping with bismuth oxide. The SEM analysis, it is clear that with the increase of doping concentration, there is a change in the surface texture of the films. Larger the doping concentration, larger would be the amount of Bi2O3 dispersed on the surface, and smaller would be the chances of reaching the gas to base material. The I-V characteristics of the pure and Bi2O3 doped MnO2 films at room temperature and at high temperature shows that the contacts fabricated on the films were ohmic in nature and the p-n junctions were randomly distributed on the surface of the film. The conductivity values of all samples were larger at room temperature than at higher temperature. It may be due to air humidity associated with the films at room temperature. The increase in conductivity with increasing temperature (above 500C) could be attributed to negative temperature coefficient and semiconducting nature of the Bi2O3 activated MnO2 samples. The Bi2O3 activated films showed very high electrical resistance of the order of 105  in air.

Bi2O3-doped MnO2, XRD, SEM, conductivity

"Synthesis and Characterization of Thick Porous Bismuth Oxide Films for Resistive Gas Sensing Applications", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 6, page no.1104-1109, June 2019, Available :http://www.jetir.org/papers/JETIR1907U36.pdf

"Synthesis and Characterization of Thick Porous Bismuth Oxide Films for Resistive Gas Sensing Applications", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 6, page no. pp1104-1109, June 2019, Available at : http://www.jetir.org/papers/JETIR1907U36.pdf