TY - JOUR
T1 - Quadruple and quintuple perovskite-layered cuprates (NdDyBa(2-x)Sr(x)Cu(2+y)Ti(2-y)O(11-δ) and NdDyCaBa(2-x)Sr(x)Cu(2+y)Ti(3-y)O(14-δ))
T2 - Their defect chemistry and electrical properties
AU - Mansourian-Hadavi, N.
AU - Ko, D.
AU - Mason, T. O.
AU - Poeppelmeier, K. R.
N1 - Funding Information:
This work was initiated under support from the National Science Foundation (DMR 91-20000) through the Science and Technology Center for Superconductivity and is currently supported by the U.S. Department of Energy under Grant . DE-FGO2-84ER45097. The authors are grateful to M. Rocci-Lane and C. R. Kannewurf for their help with Hall e!ect measurements.
PY - 2000
Y1 - 2000
N2 - The structure-property relationships of chemically substituted quadruple- and quintuple-layered cuprate perovskites, (NdDyBa(2-x)Sr(x)Cu(2+y)Ti(2-y)O(11-δ) and NdDyCaBa(2-x)Sr(x)Cu(2+y)Ti(3-y)O(14-δ), have been investigated with an emphasis on high-temperature electrical properties. Cu doping for Ti in both systems, especially the quadruple system, improves their electrical properties; however, substantial compensation by oxygen vacancies occurs. On the other hand, isovalent Sr substitution for Ba in these systems significantly reduces the ionic compensation, i.e., the [V(o..)] concentration, as evidenced by thermogravimetry and electrical measurements. Sr substitution not only reduces the Cu-O bond length in favor of hole formation but also introduces metallic behavior as evidenced by in situ high-temperature (800-400°C) electrical conductivity and Seebeck coefficient measurements plus low-temperature resistivity measurements. A master plot of high-temperature Seebeck coefficient vs hole content of known superconductors shows that the hole content necessary for superconductivity has been achieved in some of the doped quadruple systems, yet they fail to exhibit superconductivity owing to other structural limitations. (C) 2000 Academic Press.
AB - The structure-property relationships of chemically substituted quadruple- and quintuple-layered cuprate perovskites, (NdDyBa(2-x)Sr(x)Cu(2+y)Ti(2-y)O(11-δ) and NdDyCaBa(2-x)Sr(x)Cu(2+y)Ti(3-y)O(14-δ), have been investigated with an emphasis on high-temperature electrical properties. Cu doping for Ti in both systems, especially the quadruple system, improves their electrical properties; however, substantial compensation by oxygen vacancies occurs. On the other hand, isovalent Sr substitution for Ba in these systems significantly reduces the ionic compensation, i.e., the [V(o..)] concentration, as evidenced by thermogravimetry and electrical measurements. Sr substitution not only reduces the Cu-O bond length in favor of hole formation but also introduces metallic behavior as evidenced by in situ high-temperature (800-400°C) electrical conductivity and Seebeck coefficient measurements plus low-temperature resistivity measurements. A master plot of high-temperature Seebeck coefficient vs hole content of known superconductors shows that the hole content necessary for superconductivity has been achieved in some of the doped quadruple systems, yet they fail to exhibit superconductivity owing to other structural limitations. (C) 2000 Academic Press.
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U2 - 10.1006/jssc.2000.8936
DO - 10.1006/jssc.2000.8936
M3 - Article
AN - SCOPUS:0033634722
SN - 0022-4596
VL - 155
SP - 216
EP - 224
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
IS - 1
ER -