A perovskite La0.59•}0.01Li0.27•}0.01TiO3.02•}0.02 single crystal was grown by the floating zone method and its lithi um ion conductivity was measured. The conductivity was found to be predominantly ionic. The ionic conduc tivities at 333333arallel and perpendicular to the c-axis are 5.8•~10-4 and 6.8•~10-4S•Ecm-1, respectively. The anisotropy of the ionic conductivity corresponds to that of the structure, i.e., of the distribution of La ions. Furthermore, the ionic conductivity and activation energy for ion conduction are almost the same as those of a grain in polycrystalline samples, indicating that the evaluation of the ionic conductivity of poly crystalline samples was appropriate.

The (1-x)LaAlO3–xSrTiO3 solid solution system with the perovskite structure was synthesized and its dielectric behavior was investigated. The lattice parameter of (1-x)LaAlO3–xSrTiO3 increases with increasing the fraction of SrTiO3 in the system. 0.45LaAlO3–0.55SrTiO3 shows a dielectric constant ε of 34, a temperature coefficient of resonant frequency τf of -8 ppmK-1 and a dielectric loss Q of 6900, which satisfy the suggested requirements for applications to mobile communications devices. The annihilation of the ferroelectric mode of SrTiO3 corresponds to the drastic decrease of ε and τf of SrTiO3 to those of 0.25LaAlO3–0.75SrTiO3.

Molecular dynamics (MD) simulation was carried out on the high Li ion conductor, La0.6Li0.2TiO3, using the partially ionic model (PIM). MD simulation of the Li ion conductivity with the variation of mobile ion size under high pressure revealed that this compound had the optimum lattice size for Li ion conduction and that the skeletal lattice was too small for Li+ ion to show the highest conductivity.

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A novel perovskite-type oxide PbFeO 3 was successfully synthesized under a pressure as high as 7GPa, and the crystal structure, oxidation state, thermal stability, magnetic and dielectric properties were investigated. PbFeO 3 possesses an orthorhombic perovskite unit cell and there is no phase transition between room temperature and 570 K. This compound decomposes into Pb 2 Fe 2 O 5 in the vicinity of 740 K in air. According to XPS, it was found that this compound includes the Pb 2+ , Pb 4+ , and Fe 3+ ions.