Ordering of Sr atoms and loss of superconductivity in (La,Sr)2CuO4-δ crystals
Simonov V. I. , Muradynan L. A., Tamazyan R. A. , Mel'nikov O. K., Bykov A. B.,Vainshtein B. K.
It has been established on the basis of x-ray diffraction data that the statistical replacement of lanthanum by Sr atoms in (La08g ,Sroi2 )2 Cu03 92 single crystals occurs among only half of the positions of the La atoms. The reason the Tc values of ceramic samples are higher than those of single crystals in the lanthanum phases may be because of a different arrangement of Sr atoms and an associated loss of some of the oxygen from the single crystals.