The Formation of High-Tc Superconducting Phases with Four Cu-O Layers in Tl-Ca-Ba-Cu-O Systems
Zero-resistance at temperatures up to 162 K was recorded for multiphase samples with nominal composition TlCa4Ba3Cu6Ox. The compound with Tc-zero higher than 140 K was found to be highly repeatable. The compound was tentatively identified to be TlCa2Ba3Cu4Ox, tetragonal in structure with a=b=0.394 nm and c=3.95 nm and of P4/mcc space group by TEM and EDS analysis. High resolution TEM images showed that the phase is primarily of a ten-subcell structure which is consistent with a structure model with four Cu-O layers interposed between Tl-O layers. Polytype structures, consisting of four-and five-subcell structures were also observed. The five-subcell structure was identified to be of P4/mmm space group with a=b=0.394 nm and c=1.97 nm.
KeywordsEnergy Dispersive Spectrometer Lattice Image Furnace Cool Energy Dispersive Spectrometer Analysis Industrial Technology Research Institute
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