Exploring Multi-Component Superconducting Compounds by a High-Pressure Method and Ceramic Combinatorial Chemistry

In this short review, we provide some new insights into the material synthesis and characterization of modern multi-component superconducting oxides. Two different approaches such as the high-pressure, high-temperature method and ceramic combinatorial chemistry will be reported with application to several typical examples. First, we highlight the key role of the extreme conditions in the growth of Fe-based superconductors, where a careful control of the composition-structure relation is vital for understanding the microscopic physics. The availability of high-quality LnFeAsO (Ln = lanthanide) single crystals with substitution of O by F, Sm by Th, Fe by Co, and As by P allowed us to measure intrinsic and anisotropic superconducting properties such as Hc2, Jc. Furthermore, we demonstrate that combinatorial ceramic chemistry is an efficient way to search for new superconducting compounds. A single-sample synthesis concept based on multi-element ceramic mixtures can produce a variety of local products. Such a system needs local probe analyses and separation techniques to identify compounds of interest. We present the results obtained from random mixtures of Ca, Sr, Ba, La, Zr, Pb, Tl, Y, Bi, and Cu oxides reacted at different conditions. By adding Zr but removing Tl, Y, and Bi, the bulk state superconductivity got enhanced up to about 122 K.

Combinatorial chromophore assembly inside a DNA four-way junction

In 1964 first proposed by Robin Holliday as a mechanistic model to solve the mystery of how genetic information is exchanged in yeast, the DNA four-way junction or Holliday junction (HJ) was proofed to be the key in- termediate in homologous recombination and became an important tool in the field of DNA origami, computation and nanomachines. Herein we use the assembly of four modified nucleic acid strands into the planar square conformation of this higher order DNA structure to demonstrate in a proof of principle manner the cumulative effect of pyrene moieties interacting inside the junction.[1][2]