Electronic properties of La3Ni2O7 and Ln(4)Ni(3)O(10), Ln=La, Pr and Nd

Single-phase samples of La3Ni2O7.(delta) with delta=0, 0.08, 0.16 and 0.65, and Ln(4)Ni(3)O(10), Ln=La, Pr and Nd were prepared and studied by powder X-ray diffraction, thermogravimetric analysis, electrical resistivity and magnetic susceptibility. The as prepared sample, La3Ni2O6.92 and the fully reduced La3Ni2O6.35 are semiconducting, while the oxygenated La3Ni2O7.0 is metallic. For Ln(4)Ni(3)O(10.delta), when Ln = La, delta is zero and the material is metallic and Pauli paramagnetic; when Ln = Pr and Nd, delta is similar to 0.15 and an anomaly indicating a metal-to-metal transition is observed at 145 K for Pr4Ni3O10.delta and 165 K for Nd4Ni310.delta. The electrical properties of the homologous series Lan+1NinO3n+1 with n=2,3 are discussed and compared in terms of the dimensionality of the crystal lattice and the electronic band structure calculated by the extended Huckel tight binding method.