Structural and transport properties of doped LAMOX - Electrolytes for IT SOFC

Doped La_{2 - x}R_xMo_{2 - y}W_yO₉ (R = Bi, Gd, Pr, Sm, Nd; x = 0-0.5, y = 0.5-1) were synthesized via polymerized precursors method or high power mechanical milling (MM). The study of doped LAMOX genesis and structural properties using thermal analysis, XRD, TEM has revealed that for all cations substituting La-position, the pure cubic β-phase is formed from polymerized precursors after calcination at 700 °C. W-doped LAMOX have been obtained via low temperature calcination of MM products. Due to a high dispersion of powders, high density pellets of doped LAMOX ceramics have been already obtained after sintering at 950 °C. Their electrical conductivity measured by impedance spectroscopy varies in the range of 2.3-5.6 · 10^{- 3} S/cm at 630 °C depending on the doping cation nature. The self-diffusion coefficient (D_O) values calculated from corresponding conductivities is in the range of 6-14 · 10^{- 9} cm²/s at 630 °C agreeing well with those from the data of C¹⁸O₂ SSITKA for oxygen isotope exchange with powders of LAMOX.