Structure and physical properties of Ni-based quasi-one-dimensional selenides Rb0.9Ni3.1Se3 and K0.7Ni3.1Se3

The materials with quasi-one-dimensional crystal structure have gained intense interest because of their novel structure and related properties such as electron correlations , charge-density wave and potential superconductivity . Here we report two new Ni-based quasi-one-dimensional selenides : Rb 0.9 Ni 3.1 Se 3 and K 0.7 Ni 3.1 Se 3 . These two compounds are nonstoichiometric and composed of one-dimensional (Ni 3 Se 3 ) ∞ infinite chains with face-sharing Ni 6 octahedra along the c direction. It is found that the interchain distance in these compounds is strongly influenced by the radius of intercalated alkali-metal cations, while the configuration of (Ni 3 Se 3 ) ∞ chains is basically unaffected. The conductivity measurement indicates the metallic behavior of Rb 0.9 Ni 3.1 Se 3 and K 0.7 Ni 3.1 Se 3 . Meanwhile, the magnetic susceptibility reveals the spin-glass state below 10 K. It is indicated that the magnetic moments in these compounds are related to the Ni Ni bonding distance. First-principles calculation reproduces the metallic state of this 133 phase, and also suggests that the magnetic interaction is attributed to the extra Ni in structure. These compounds form a Ni-based quasi-one-dimensional material family, which provides new platform to understand the structure-property relationship of quasi-one-dimensional materials, and also offer a series of potential precursors to synthesis the novel (Ni 3 Se 3 ) ∞ molecular wires .