Quasi-Low-Dimensional Transition Metal Compounds: Synthesis and Characterization

这个实验计划的重点是合成处于电子和结构不稳定边缘的强关联电子系统的新材料，并以可控的方式微调通过不稳定区域的竞争电子相互作用。将特别重视单晶样品的制备，以研究其结构和与取向有关的物理性质，包括电阻率、磁化率、光学和X射线吸收近边光谱。与电荷密度波/自旋密度波和/或磁有序的开始相关的金属-绝缘体转变；以及超导电性将被寻找和表征，并将强调结构和物理性质的关系。相关系统包括：(A)。过渡金属钙钛矿和Ruddlesden-Popper相，An+1BnO3n+1，其中A=稀土和/或碱和/或碱土金属；B=Mn，Co，Fe(Mn/Fe)，Ni和Ru，n=1，2，3；(B)。Nb簇合物；和(C)。选择了低维三元和四元过渡金属硫化物的新结构类型。%这些研究不仅有望从根本上了解和控制新型电子/磁性材料的性质，而且还将为计算机、传感器和通信等微电子和磁电子领域的潜在应用提供先进的材料。这些都是保持美国在全球技术领先地位的关键领域。此外，固体化学/材料科学的本科生、研究生和博士后研究员的教育和培训对于迎接二十一世纪的技术挑战至关重要。

The focus of this experimental program is to synthesize new materials of strongly correlated electron systems that are on the verge of electronic and structural instabilities, and to fine-tune the competing electronic interactions through the unstable region in a controlled way. Particular emphasis will be placed on the preparation of single crystal specimens to study the structural and orientation-dependent physical properties, including electrical resistivity, magnetic susceptibility, optical and X-ray absorption near-edge spectroscopies. Metal-insulator transitions associated with the onset of charge density waves/spin density waves and/or magnetic ordering; and superconductivity will be sought and characterized, and structural and physical property relationships will be stressed. Systems of interest include: (a). transition metal perovskites and Ruddlesden-Popper phases, An+1BnO3n+1 with A=rare earth and/or alkali and/or alkaline earth metal; B=Mn, Co, Fe (Mn/Fe), Ni and Ru, n=1, 2, 3; (b). niobium cluster compounds; and (c). selected novel structure types of low-dimensional ternary and quaternary transition metal chalcogenides.%%%These studies are expected to yield not only fundamental understanding and control of the properties of novel electronic/magnetic materials, but also to provide advanced materials for potential applications in microelectronics and magnetoelectronics including computers, sensors and communications. These are critical areas for maintaining US technological leadership worldwide. Moreover, the education and training of undergraduate and graduate students and postdoctoral fellows in solid state chemistry/materials science is essential to meet the technological challenges of the twenty first century.