Recently superconductivity at 9 -15 K was discovered in an infinite-layer nickelate (Nd0.8Sr0.2NiO2 films), which has received enormous attention.Since the Ni 1+ ionic state in NdNiO2 may have the 3d 9 outer-shell electronic orbit which resembles that of the cuprates, it is very curious to know whether superconductivity discovered here has similar mechanism as that in the cuprates. By using a three-step method, we successfully synthesize the bulk samples of Nd1-xSrxNiO2 (x = 0, 0.2, 0.4). The X-ray diffractions reveal that all the samples contain mainly the infinite layer phase of 112 with some amount of segregated Ni. This has also been well proved by the SEM image and the EDS composition analysis. The resistive measurements on the Sr doped samples show insulating behavior without the presence of superconductivity. Temperature dependence of the magnetic moment under high magnetic fields exhibits a Curie-Weiss law feature with the paramagnetic moment of about 2B/f.u.. By applying pressure on Nd0.8Sr0.2NiO2 up to about 50.2 GPa, we find that the strong insulating behavior at ambient pressure is significantly suppressed, but superconductivity has not been observed either. Since the lattice constants derived from our XRD data are very close to those of the reported superconducting films, we argue that the superconductivity in the reported film may not originate from the expected Nd0.8Sr0.2NiO2, but arise from the interface or the stress effect.Since the discovery of high critical temperature superconductivity (HTS) in cuprates in 1986 [1] , there are plenty of experimental and theoretical studies to explore the intrinsic mechanism for superconductivity [2][3][4][5] . There is a general agreement that the parent compound of cuprates like La2CuO4 is a Mott insulator with a charge transfer gap and long-range antiferromagnetic (AF) order [6] . With chemical doping, the long-range AF order will be suppressed at a hole doping level (p  0.02) and d-wave superconductivity emerges at a higher doping level (p  0.05) [7][8][9] . After the efforts more than three decades, some common features have been observed, although the intrinsic pairing mechanism of HTS remains unresolved yet. These include two-dimensional electronic structure and coexistence with an AF order or spin fluctuations, all these also occur in most iron-based [10] and heavy fermion superconductors [11] .Moreover, in cuprates, it is also important that the spin S = 1/2 magnetic moment from 3d 9 electrons form the basic structure of the AF order. One intuitive way to explore the pairing mechanism of cuprates is to find additional high-TC superconductors with different transition metals but similar crystal and

We report the crystal structures and physical properties of trilayer nickelates Nd4Ni3O10 and Nd4Ni3O8. Measurements of magnetization and electrical resistivity display contrasting behaviors in the two compounds. Nd4Ni3O10 shows a paramagnetic metallic behavior with a metal to metal phase transition(T * ) at about 162 K, as revealed by both magnetic susceptibility and resistivity. Further magnetoresistance and Hall coefficient results show a negative magnetoresistance at low temperatures and the carrier type of Nd4Ni3O10 is dominated by hole-type charge carriers. The significant enhancement of Hall coefficient and resistivity below T * suggest that effective charge carrier density decreases when cooling through the transition temperature. In contrast, Nd4Ni3O8 shows an insulating behavior despite small value of resistivity at room temperature. The compound shows paramagnetic behavior, with the similar magnetic moments as in Nd4Ni3O10 derived from the Curie-Weiss fitting. This may suggest that the magnetic moments in both systems are contributed by the Nd ions. By applying pressures up to about 49 GPa, the insulating behavior is still present and becomes even stronger. Our results suggest that the different Ni configurations (Ni 1+/2+ or Ni 2+/3+ ) and competition between localized and itinerant electrons may account for the contrasting behaviors in trilayer nickelates Nd4Ni3O10 and Nd4Ni3O8.

The nontoxic superconductor (Cu,C)Ba2Ca3Cu4O11+δ has the highest irreversibility line for possible applications above the LN2 temperature.