Comment On "Origin Of The Superconductivity In The Y-Sr-Ru-O And Y-Sr-Cu-O Systems"

Galstyan [Phys. Rev. B 76, 014501 (2007)] asserted that superconductivity reported for Sr(2)YRu(1-u)Cu(u)O(6) is due to inclusions of YSr(2)Cu(3)O(7). We have synthesized samples of this magnetic material (u=0.10) which exhibit diamagnetism exceeding that possible even if all of the available dopant Cu were present in YSr(2)Cu(3)O(7). Our materials were studied with neutron diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and SQUID magnetometry. We found no evidence for inclusions of YSr(2)Cu(3)O(7). Despite their claim, this is in agreement with a primary finding of Galstyan that granular YSr(2)Cu(3)O(7) is present only in material doped with Cu at 250% of the known Cu solubility limit. The lack of superconductivity at low Cu doping in their material is likely due to their failure to follow published synthesis procedures. It is concluded that the findings of Galstyan actually support our contention that properly synthesized Sr(2)YRu(1-u)Cu(u)O(6) is a single phase material which exhibits high temperature superconductivity.