Neutron powder diffraction study of Pb2Sr2YCu3O8, the prototype of a new family of superconductors

Structural aspects of superconducting cuprates

“…These cuprates contain Cu + ions and are prepared in a reducing atmosphere to ensure that Pb is divalent. The compounds crystallize in an orthorhombic cell (Cmmm) with a = 5.393, b--5.431 and c = 15.733.~, for Pb2Sr2YCu308 (Cava et al, 1989). The structure ( …”

OK-edge and CuL23-edge XANES study on the concentration and distribution of holes in the(Pb2/Karppinen1, Kotiranta2, Yamauchi3 et al. 2001Phys. Rev. B214170View full textAdd to dashboardCite

“…Also with the oxygen-deficient configuration at z Ϸ0, ͑Pb 2/3 Cu 1/3 ͒-3212 is an antiferromagnetic semiconductor if the Q-metal layer between the two CuO 2 planes in the CuO 2 -Q-CuO 2 block is composed of rare-earth element͑s͒ only. 22 Only when substituting part of the trivalent R ions by divalent Ca, superconductivity arises.…”

Preparation and Microstructural Investigation of the High?Tc Superconductor Pb2Sr2Y0.5Ca0.5Cu308

“…In detail however, the structure is likely to be more complex. Recent analysis indicates that the contentious space group issue is still unresolved (Cava et al 1989;Subramaniam et al 1989). Although the orthorombic cell gave a good fit to the powder X-ray diffraction (XRD) data, a shoulder on the (314) reflection could be indicative of monoclinic symmetry.…”

“…In PbzSrzYo.sCao·sCu30s the lead atoms are in square pyramidal coordination to oxygen and separated along c by Cu 1 + ions in linear coordination (when 8 = 0). It has been suggested (Cava et al 1989) * Paper presented at the DITAC Conference on Superconductivity held in Canberra, 13-14 that the oxygen content of these CuOo chains is variable and that they act as electron acceptors which induce the holes necessary for superconductivity in the CuO" pyramidal planes. Strontium, calcium and rare-earth atoms fill the larger interstices (8 or 9 coordination) between the CuOo polyhedra.…”

“…Ganguli et al 1987;Liu et al 1987). Following this technique, Cava et al (1988) systematically explored a distinct class of high-Tc superconductors having the stoichiometry PbzSrzACu30s+o' Neither lanthanide (Ln) endmembers (namely PbzSrzLnCu30s) nor oxygen-rich compounds (0 < 8 ~ 1 ·8) were superconductors. However, coupled substitution of alkali earth elements (Ca, Sr) with lanthanides or yttrium yielded superconducting compounds, having the general formula PbzSrzLnl-x(Ca, Sr)xCu30S+o'…”