Preparation of V doped lanthanum silicate electrolyte ceramics by combustion method and study on conductance mechanism

Vanadium doped La 9.33 (x = 0.5, 1.0, 1.5) (LSVO) electrolyte powder was prepared by combustion method at 600 degrees C for 5-7 min. The powder was sintered at 1500 degrees C for 3 hours to prepare LSVO ceramics. XPS, IR, XRD, and EIS analysis show that V5+ doping replaces Si4+ in [SiO4] to form [Si(V)O-4] tetrahedron. With the increase in x, the lattice volume increase. When x = 2.0, the LaVO4 phase was formed, indicating that the limit doping amount of V5+ replacing Si4+ is x <= 1.5. The conductivity of LSVO increases significantly with the increase in x (x <= 1.0), which attributed to the xV5+27f6;xSi4+xVSi center dot+1/2xOi*// defect reaction caused by V5+ doping. The addition of the interstitial oxygen Oi* in 6(3) channels and the increase of lattice volume leads to increased conductivity. When x = 1.0, the highest conductivity is 1.46 x 10(-2) S center dot cm(-1) (800 degrees C). The doping enhancement conductivity mechanism is the Interstitial oxygen defect-Lattice volume composite enhancement mechanism.