La_(0.9)Sr_(0.1)Ga_(0.8)M_(0.2)O_(3-#delta#) (M=Mn, Co, Ni, Cu or Zn): Transition metal-substituted derivatives of lanthanum-strontium-gallium-magnesium (LSGM) perovskite oxide on conductor

摘要

Perovskite oxides of the general formula,La_(0.9)Sr_(0.1)Ga_(0.8)M_(0.2)O_(3-#delta#) for M=Mn, Co,Ni, Cu and Zn, have been prepared and investigated. All theoxides exhibit high electrical conductivities (#sigma# approx10~(-2) S/cm at 800 deg C) comparable to that of the bestperovskite oxide ion conductor,La_(0.9)Sr_(0.1)Ga_(0.8)M_(0.2)O_(2.85 )(LSGM) (#sigma#approx 8 X 10~(-2) S/cm at 800 deg C). While M = Mn, Co, Ni,Cu members appear to be mixed conductors with a variableelectronic contribution to the conductivity, especially at highoxygen partial pressures pO_2 >= 1 atm), arising from mixed-valency of the transition metals, the M = Zn(II) phase is a pureoxide ion conductor exhibiting a conductivity (#sigma# approx1.5 X 10~(-2) S/cm at 800 deg C) that is slightly lower than thatof LSGM. The lower conductivity of the M = Zn(II) derivativecould be due to the preference of Zn(II) for a tetrahedral oxygen coordination.