Response characteristics to reducing gases in BaTiO3-based thick films

• Published in: Journal of alloys and compounds Vol. 391; no. 1-2; pp. 123 - 128
• Main Authors: PARK, K, JANG, K. U
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier 05.04.2005
• Subjects: Exact sciences and technology; Physics; Inorganic compounds; Electrical conductivity; Curie point; Tetragonal lattices; BaTiO3; Thick films; Transition element compounds; Barium titanates; Perovskites; High temperature; Interstitial solid solution; Thick film; Electrical resistivity; Sintering; Graphite; Reducing gas; Gallium selenides
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2004.07.087

Barium titanate is an insulator with a large energy gap of ~3.05 eV at room temperature. It can be converted to an n-type semiconductor when trivalent ions such as Y3+ and La3+ or pentavalent ions such as Sb5+ and Nb5+ are substitutionally incorporated at Ba or Ti sites as donor dopants. The added graphite formed interstitial solid solutions with Ba0.999Sb0.001TiO3 and did not cause any modification in the crystalline structure. The sintered bodies of the BaTiO3-based thick films showed a tetragonal perovskite structure. The response characteristics of the electrical resistivity for the BaTiO3-based thick films to reducing gases such as CH4, N2 and CO were studied. The electrical resistivities below the Curie temperature (~120 deg C) in all the atmospheres were nearly the same irrespective of atmospheres. However, the electrical resistivities at high temperatures ( > ~150DGC) strongly depended on the atmosphere. The response characteristics of the electrical resistivity to reducing gases followed the order of CO > CH4 > N2. The discrepancy in the resistivities measured at high temperatures in air and reducing gases became remarkable with increases in graphite contents.