Electrical and magnetic properties of NdTiO3+δ

The electrical and magnetic properties of NdTiO3+δ have been measured and correlated with unit cell parameters and composition of the samples. NdTiO3+δ exhibited the GdFeO3-type structure across the whole of the composition range, which in our investigations was found to extend approximately from NdTiO3.05 to NdTiO3.15. Over this range, the lattice contracted slightly, consistent with a rotation of the TiO6 octahedra in the a-c plane. At compositions closest to NdTiO3.05, the materials were semiconducting and displayed a ferromagnetic transition at a temperature of about 90 K. At compositions above about NdTiO3.11, the materials were metallic and did not show any magnetic transitions. Several samples of composition close to NdTiO3.11 showed a metal-insulator transition at typically ∼105 K. Electron microscopy revealed the presence of a microdomain texture in some samples, indicating that the results apply to an average structure rather than a genuine single phase. The results mirror those found for non-stoichiometric LaTiO3+δ and can be explained in a similar fashion.