Chaudhuri, S P and Patra, S K and Chakraborty, A K (1999) Electrical resistivity of transition metal ion doped mullite. Journal of the European Ceramic Society, 19 (16). pp. 2941-2950. ISSN 0955-2219

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The electrical resistivity of pure mullite (3Al(2)O(3). 2-SiO2) varies from 10(13) ohm-cm at room temperature (r.t.) to 10(4) ohm-cm at 1400 degrees C. It was observed that by doping mullite with the 3d-type transition metal ions, e.g. Mn, Fe, Cr and Ti, the resistivity of mullite could be reduced to 10(11) ohm-cm, i.e. 1/100 that at r.t. and 1/5 that at 1400 degrees C. The resistivity of doped and undoped mullite decreased by 6-5 orders at about 500-600 degrees C but 4-3 orders between this temperature and 1400 degrees C. The 3d orbital electrons, the oxidation states and the concentration of the transition metal ions as well as the sites of mullite lattice occupied by the ions were found responsible for lowering of resistivity of mullite. Evidence of the presence of Mn2+, Mn3+, Fe3+, Cr3+ and Ti4+ ions in mullite had been obtained which entered the octahedral site. The Ti4+ ion which substituted Al3+ ion in the octahedral site of mullite structure appeared to be the most efficient one to reduce the resistivity. This has been confirmed by the results of activation energy of resistivity/band gap energy, Eg which was the lowest for mullite doped with 1.0 wt% Ti4+ ion. At 1.0 wt% concentration level, these ions lowered the resistivity of mullite to minimum. (C) 1999 Elsevier Science Ltd. All rights reserved.

Item Type: Article
Uncontrolled Keywords: Resistivity; Electrical conductivity; Mullite; Transition Metal oxides
Subjects: Engineering Materials
Depositing User: Bidhan Chaudhuri
Date Deposited: 18 Jun 2012 07:47
Last Modified: 18 Jun 2012 07:47

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