3 · 10Al 2O 3 and 90Pr 0.95Sr 0.05F 2.95 · 10Al 2O 3]]>

摘要

The two-phase fluoride oxide composite 90Pr~(0.95)Sr~(0.05)F~(2.95)· 10Al~(2)O~(3)(mol %) composed of a highly conductive fluoride matrix with a tysonite structure (LaF~(3)) and aluminium oxide is of interest as a solid electrolyte membrane in a potentiometric oxygen sensor with an auxiliary electrode. The ionic conductivity of the composite 90Pr~(0.95)Sr~(0.05)F~(2.95)· 10Al~(2)O~(3)has been determined by impedance spectroscopy in vacuum (~0.1 Pa) in the temperature range of 293?700 K. Its dominant component is the conducting non-stoichiometric tysonite phase Pr~(0.95)Sr~(0.05)F~(2.95). To estimate the contribution of this phase to the composite conductivity, the conductivities of the single-phase (single-crystal) PrF~(3)and Pr~(0.95)Sr~(0.05)F~(2.95)bases and a twophase composite 90PrF~(3)· 10Al~(2)O~(3)with a stoichiometric fluoride matrix PrF~(3)have been investigated. The use of the nonstoichiometric phase Pr~(0.95)Sr~(0.05)F~(2.95)as a composite matrix instead of PrF~(3)leads to an improvement of ionic conductivity by a factor of ~200: to 5 × 10_(–3)S/cm at 400°C.