In situ neutron diffraction study on fast oxide ion conductor LaGaO3-based perovskite compounds

The crystal structures of LaGaO3, LaGa0.9Mg0.1O2.95, and La0.9Sr0.1Mg0.1O2.9 have been investigated by high-temperature neutron powder diffraction in order to clarify a mechanism for high oxide ion conduction properties in LaGaO3-based compounds. Parent phase LaGaO3 crystallized in the orthorhombic (Pbnm) up to 150 degrees C and the rhombohedral (R (3) over barc) at between 160 and 800 degrees C. LaGa0.9Mg0.1O2.95 crystallized in the orthorhombic (Ibmm) up to 340 degrees C and the rhombohedral (R (3) over barc) at between 350 and 800 degrees C. On the other hand, La(0.9)Sr(0.1)Ga(0.1)Mgo(0.1)O(2.9) crystallized in the monoclinic (12/a) up to 400 degrees C and the rhombohedral (lR/a) at between 410 and 800 degrees C. The correlations between the crystal structures and conduction properties of LaGaO3-based materials were discussed on the basis of the analytical results.