Oxide electronics

Abstract:

We report the synthesis under pressure, the critical temperature and the structural characteristics of YSr2Cu3Ow. The compound does not form at normal pressure, but, once formed, can be retained at normal pressure in a metastable state. The synthesis was carried out in a multi-anvil apparatus at 30 kBars and 1050°C. The as-prepared sample was found to become superconductor with a Tc of ≈ 63K. Tc increased up to ≈ 70 K after annealing in oxygen at 290°C. The refinement of the neutron diffraction data indicated that the as prepared YSr2Cu3Ow is tetragonal (a=3.7855 Å and c=11.386 Å) and the oxygen content, w, is ≈ 6.84.

Abstract:

High real-space resolution atomic pair distribution functions (PDFs) have been obtained from ZnSe(1-x)Te(x) using neutron powder diffraction. Distinct Zn-Se and Zn-Te nearest neighbor (nn) bonds, differing in length by delta_r= 0.14Angstroms, are resolved in the measured PDF allowing the evolution with composition of the individual bond-lengths to be studied. The local bond-lengths change much more slowly with doping than the average bond-length obtained crystallographically. The nn bond-length distributions are constant with doping but higher-neighbor pair distributions broaden significantly indicating that most of the strain from the alloying is accommodated by bond-bending forces in the alloy. The PDFs of alloys across the whole doping range are well fit using a model based on the Kirkwood potential. The resulting PDFs give excellent agreement with the measured PDFs over the entire alloy range with no adjustable parameters.