Nickel 1+/2+ Oxides and Oxyfluorides Isoelectronic with Superconducting Cuprates

非技术综述：超导材料可以无损耗地传输电流并产生高磁场，这使得它们在磁共振成像、悬浮列车、电机和发电机中得到了应用。然而，在相对较高的温度下超导的成熟铜基材料的超导机制仍然没有完全被理解。最近在掺杂NdNiO2薄膜中发现的超导电性证实了这些以镍为基础的材料可以表现出类似于超导铜基材料的物理性质。本项目在材料研究部固态和材料化学项目的支持下，合成了新型Ni1+/Ni2+镍基材料，并对其结构-性能关系进行了详细的研究。这将影响我们对高温超导机制的理解，潜在地指导新超导体的设计，并为国家能源安全做出贡献。该项目的教育影响将通过培训无机合成、电化学、结晶学和各种表征技术领域的研究生和本科生来实现。PI领导着为来自大新奥尔良地区的教师设立的高中科学教师俱乐部。教师俱乐部旨在让教师分享有效的教学策略，并就当前的研究课题对教师进行教育。为了改善科学教育的目标，同样由PI建立的教育设备借阅图书馆正在得到加强，新的演示将用于扩展到高中生。技术摘要：具有无限NiO2正方形平面层的Ni1+/Ni2+镍酸盐是唯一真正的电子(D9/D8)和结构(Mo2面)类似于高温超导铜的化合物。然而，只有少数这样的镍酸盐是已知的，并且还没有对掺杂的D9/D8镍酸盐进行系统的研究。在该项目中，在材料研究部固态和材料化学计划的支持下，对掺杂和未掺杂的Ni1+/Ni2+镍酸盐和含NiO2平面的氟氧化物的合成、结构和性能进行了全面的研究，正在产生新的铜酸盐类似物和系统的结构-性能关系。人们正在研究多个化合物家族：掺杂的d8/d9和d9/d10比类似于超导铜酸盐的无限层镍盐，新的n=4和5个T素镍酸盐系列的同系物以及氟化的T素镍酸盐。采用高压高温合成法合成了一些掺杂的母体Ruddlesden-Popper化合物。采用低温、软化学技术制备最终的(还原)化合物。除了通过粉末X射线和中子衍射实验确定结构外，还通过常压和高压磁测量和输运测量、固态核磁共振和Muon自旋旋转技术研究了物理性质。该项目旨在发现镍酸盐超导体，并对铜酸盐超导电性以及更广泛地说，对具有强关联电子的材料有新的基本见解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY: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.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.TECHNICAL SUMMARY: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.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.