Stacks of Intrinsic Josephson Junctions (IJJs) with atomic size are naturally present in layered high-Tc superconductors (HTS) such as Bi2Sr2CaCu2O8+δ (Bi-2212), La2-xSrxCuO4 (LSCO) and RareEarth-123. Among the possible IJJs applications, high frequency devices can take advantage from the large Josephson plasma frequency found in some HTS IJJs. In particular, Y-123 has the highest Josephson plasma frequency and its properties can be modulated by cationic substitutions, as already noticed for Pb doped Bi-2212. In a future context of IJJs exploitation, HTS whiskers, like the ones belonging to the Y-123 system, are suitable to realize studies and devices based on IJJs, which require high homogeneity of the IJJs properties on the micrometric scale. Their highly crystalline nature, low defect concentration and excellent superconducting features provide this aspect. In this work, a study is presented on the structural and superconducting variations induced by doping with elements able to favour the increase of the superconducting critical temperature and the yield of the synthesis process. Elements (Al, Sb, Te, Ga) addition was systematically modulated in the nominal cationic stoichiometry of (Y,Ca)BCO-123. The effects of the elemental incorporation in the structure were investigated using single crystal X-ray diffraction technique and SEM/EDS measurements to obtain information on cationic distribution. In particular, single crystal X-ray diffraction successfully correlate the cationic insertion with the substitution sites, highlighting sometimes a modification of coordination frameworks of copper. The electrical characterization indicates corresponding changes in the conducting properties of the materials.
Structural modulation by chemical substitution in single crystal HTc superconductors
AGOSTINO, Angelo;BONOMETTI, Elisabetta;PASCALE, LISE;OPERTI, Lorenza;TRUCCATO, Marco;
2013-01-01
Abstract
Stacks of Intrinsic Josephson Junctions (IJJs) with atomic size are naturally present in layered high-Tc superconductors (HTS) such as Bi2Sr2CaCu2O8+δ (Bi-2212), La2-xSrxCuO4 (LSCO) and RareEarth-123. Among the possible IJJs applications, high frequency devices can take advantage from the large Josephson plasma frequency found in some HTS IJJs. In particular, Y-123 has the highest Josephson plasma frequency and its properties can be modulated by cationic substitutions, as already noticed for Pb doped Bi-2212. In a future context of IJJs exploitation, HTS whiskers, like the ones belonging to the Y-123 system, are suitable to realize studies and devices based on IJJs, which require high homogeneity of the IJJs properties on the micrometric scale. Their highly crystalline nature, low defect concentration and excellent superconducting features provide this aspect. In this work, a study is presented on the structural and superconducting variations induced by doping with elements able to favour the increase of the superconducting critical temperature and the yield of the synthesis process. Elements (Al, Sb, Te, Ga) addition was systematically modulated in the nominal cationic stoichiometry of (Y,Ca)BCO-123. The effects of the elemental incorporation in the structure were investigated using single crystal X-ray diffraction technique and SEM/EDS measurements to obtain information on cationic distribution. In particular, single crystal X-ray diffraction successfully correlate the cationic insertion with the substitution sites, highlighting sometimes a modification of coordination frameworks of copper. The electrical characterization indicates corresponding changes in the conducting properties of the materials.
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