Synthesis and characterization of perovskite-type BaMg₀.₃₃Nb₀.₆₇₋ₓFeₓO₃₋δ for potential high temperature CO₂ sensors application
2013
Kannan, Ramaiyan | Mulmi, Suresh | Thangadurai, V. (Venkataraman)
Mixed ionic-electronic conducting BaMg₀.₃₃Nb₀.₆₇₋ₓFeₓO₃₋δ was successfully synthesized by conventional solid state method in air at elevated temperature. Fe-doping helped to increase the total conductivity, while the chemical stability under CO₂ at elevated temperatures and under H₂O vapour at boiling conditions decreased with increasing Fe content above x = 0.17 in BaMg₀.₃₃Nb₀.₆₇₋ₓFeₓO₃₋δ. Maximum total conductivity of 10⁻³ S cm⁻¹ at 300 °C was obtained for BMNF33 in air, and further increase in Fe content lowered the electrical conductivity, particularly at low temperatures. Activation energy, in the range of 300–700 °C, for total electrical conduction was found to decrease in air by the incorporation of Fe in BaMg₀.₃₃Nb₀.₆₇O₃ (BMN) (BMN: 0.96 eV; BMNF17: 0.72 eV; BMNF33: 0.25 eV). Furthermore, the x = 0.17 composition demonstrated excellent CO₂ sensing characteristics at 700 °C. The investigated perovskite-type metal oxides seem to be promising candidates for monitoring CO₂ (ppm level in air) at elevated temperatures.
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