High temperature ionic conductivity in the trivalent ceramic electrolytes: LaAl_(11)O_(18) and LaAl_(12)O_(18)N

摘要

LaAl_(11)O_(18) and LaAl_(12)O_(18)N which adopt the magnetoplumbite type structure were prepared by high temperature sintering techniques from La_2O_3, α-Al_2O_3 and AlN powders. Phase purity was confirmed by powder XRD and IR spectroscopy. Impedance data for ceramic samples with Pt electrodes revealed an intra-granular ionic (La~(3+)) conductivity with activation energies E_a(LaAl_(11)O_(18)) = 2.5 eV and E_a(LaAl_(12)O_(18)N) = 1.6 eV. At ～1540 K their conductivity is comparable to that for Sr-Li-β-alumina with σ ～ 3 X 10~(-5) S cm~(-1).