Study of Apatite-Type Lanthanum Silicate Electrolyte Materials

摘要

La9Ba1Si6O_(26.5) of apatite structure type was synthesised and characterised by SEM and impedance spectroscopy. An ionic conductivity higher than 10~(-2) S.cm~(-1) was measured at 700°C. The crystalline structure was investigated by neutron powder diffraction at room temperature and at 700°C. The existence of some extra oxide ions was demonstrated but no new crystallographic site was evidenced to take into account the excess of oxygen. Moreover, an important role of the silica tetrahedrons in the conduction mechanism was suggested by the large anisotropic thermal displacement parameters of the [SiO4] oxygen atoms.^