In Nd3.5Sm0.5Ni3O8which has basically the same crystal structure and the similar electrical configuration (Ni+3d9/Ni2+3d8mix valence state) with high-Tccuprate, it has been found that this material shows metallic behaviour down to about 20 K by intercalation and subsequent deintercalation with sulfur. This is the first observation of the metallic state in this system. It is unclear why sulfur-intercalation and deintercalation induce the metallic state. We speculate that sulfur works as an effective getter for removing the interstitial apical oxygen which impedes the metallic conduction. However, the weak localization of carriers in the NiO2planes still remains below 20 K and the localization may be one of the obstacles to occurrence of possible superconductivity.

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Nd3.5Sm0.5Ni3O8 is a candidate for high-Tc superconductor, due to the close structural and electrical similarities with high-Tc cuprates. In electrical resistivity measurement, Nd3.5Sm0.5Ni3O8 shows a semiconducting behavior. However, by intercalation and subsequent deintercalation treatments with sulfur, Nd3.5Sm0.5Ni3O8 displays metallic behavior down to 20 -40 K, followed by the weak semiconducting tendency at lower temperatures. In this study, the electrical resistivity measurements under high pressures up to 2 GPa were performed for a semiconducting sample of Nd3.5Sm0.5Ni3O8. We discuss the electrical properties of this material, combining the high-pressure resistivity data with measurements on metallic samples at ambient pressure.

Electrical resistivity was measured under pressure of up to 3 GPa for 2-dimensional nickelate La 3-x Nd x Ni 2 O 6 with x = 2 and 2GPa for 2-dimensional Ruthenate La 1.5-x Cd x Nd 0.5 RuO 5 with x = 0.5. Both compounds seem to be candidate for high-T c superconducting materials in the sense of structural and electrical state similarities with high-T c cuprate and 2-leg ladder system. In both compounds the electrical resistivity decreases with applied pressure increasing. However metallic state and superconducting transition were not observed under pressure.

Nd3.5Sm0.5Ni3O8 is a candidate for high-Tc superconductor, due to the close structural and electrical similarities with high-Tc cuprates. In electrical resistivity measurement, Nd3.5Sm0.5Ni3O8 shows a semiconducting behavior. However, by intercalation and subsequent deintercalation treatments with sulfur, Nd3.5Sm0.5Ni3O8 displays metallic behavior down to 20 -40 K, followed by the weak semiconducting tendency at lower temperatures. In this study, the electrical resistivity measurements under high pressures up to 2 GPa were performed for a semiconducting sample of Nd3.5Sm0.5Ni3O8. We discuss the electrical properties of this material, combining the high-pressure resistivity data with measurements on metallic samples at ambient pressure.