NSF Award
2004740
NON-TECHNICAL SUMMARY:<br/>Superconducting materials can transmit electric current without losses and create high magnetic fields, which has led to their application in magnetic resonance imaging, levitation trains, electric motors and generators. However, the mechanism of superconductivity in well-established copper-based materials that superconduct at relatively high temperature is still not fully understood. The recent discovery of superconductivity in thin films of doped NdNiO2 confirmed that these materials, based on nickel, can exhibit physics similar to the superconducting copper-based materials. In this project, supported by the Solid State and Materials Chemistry program within the Division of Materials Research, new Ni1+/Ni2+ nickel-based materials are synthesized and their structure-property relationships are investigated in detail. This impacts our understanding of the high-temperature superconductivity mechanism, potentially guiding the design of new superconductors and contributing to national energy security.<br/><br/>Educational impacts of the project will be achieved by training graduate and undergraduate students in the areas of inorganic synthesis, electrochemistry, crystallography, and various characterization techniques. The PI leads the High School Science Teachers Club for teachers from the Greater New Orleans area. The Teachers Club is designed to involve teachers in sharing effective teaching strategies and to educate teachers on current research topics. With the goal of improving science education, the Educational Equipment Lending Library, also established by the PI, is being enhanced with new demonstrations to be used in outreach to high school students.<br/><br/>TECHNICAL SUMMARY:<br/>Ni1+/Ni2+ nickelates with infinite NiO2 square-planar layers are the only real electronic (d9/d8), and structural (MO2 planes) analogues to high-temperature superconducting cuprates. However, only a few such nickelates are known and no systematic investigation of doped d9/d8 nickelates has been performed. In this project, supported by the Solid State and Materials Chemistry program within the Division of Materials Research, comprehensive investigations of syntheses, structures and properties of doped and undoped Ni1+/Ni2+ nickelates and oxyfluorides with NiO2 planes are producing new cuprate analogues and systematic structure-property relationships. Multiple families of compounds are being studied: doped infinite-layer nickelates with d8/d9 and d9/d10 ratios analogous to the superconducting cuprates, new n = 4 and 5 homologues of T-prime nickelate series as well as fluorinated T-prime nickelates. High-pressure, high-temperature synthesis is used for preparation of some doped parent Ruddlesden-Popper compounds. Low temperature, soft chemistry techniques are used for the preparation of the final (reduced) compounds. In addition to structure determination by powder X-ray and neutron diffraction experiments, physical properties are investigated by ambient and high pressure magnetic and transport measurements, solid-state NMR and muon spin rotation techniques. The project aims for discovery of nickelate superconductors and new fundamental insight into cuprate superconductivity and, more generally, into materials with strongly correlated electrons.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
