(Tl, Pb, Cu)Sr2(Tl, Pb, Cu)2Cu2O8−δ: a nonsuperconducting Tl-1222 cuprate with both heavy atom single and oxygen depleted double layer motifs |
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Authors: | H. H. Otto S. Ringshandl R. Baltrusch |
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Affiliation: | Materialwissenschaftliche Kristallographie, TU Clausthal, Adolph-Roemer-Straße 2A, D-38678 Clausthal-Zellerfeld, Germany |
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Abstract: | An account is given of the synthesis and structural investigation of a newly discovered tetragonal (Tl, Pb, Cu)Sr2(Tl, Pb, Cu)2Cu2O8−δ compound (Tl-1222* phase) with both (Tl, Pb, Cu)O single and oxygen depleted (Tl, Pb, Cu)2Ox double layer motifs, space group I4/mmm, lattice parameters a=3.8405(2), c=29.2536(5) Å, and Dx=7.46 g cm−3. Micaceous and highly reflecting black single crystals of 1 mm×1 mm×3–5 μm size were obtained from a Tl2O3- and CuO-rich partial melt. The as-grown compound is nonsuperconducting. The very thin crystals are extremely liable to bend out of shape. Deterioration could not be observed within the period of a year under ambient conditions. The complex crystal structure has been solved using single crystals. We take note of the similarity of the unit cell dimensions to superconducting (Tl, Cu)2Ba2(Ca, Tl)Cu2O8 (Tl-2212 phase) with TlO double rocksalt layers, and compare crystal-chemical details of similar compounds. Apart from the possibility of obtaining superconducting properties by suitable doping, the mechanical properties of the new material are very attractive from the point of view of its use as highly scattering composite layers of an X-ray monochromator. |
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Keywords: | Oxide superconductors Synthesis (chemical) Lattice constants Single crystals Crystal structure Doping (additives) Thallium compounds Nonsuperconducting cuprates |
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