TY - JOUR
KW - High temperature superconductors
KW - Superconducting materials
KW - Neodymium compounds
KW - Ceramic materials
KW - Oxide superconductors
KW - Crystals - Structure
KW - Neodymium Cerium Copper Oxides
KW - Thermogravimetric Analysis
AU - J.M Tarascon
AU - E Wang
AU - L.H Greene
AU - Ramamoorthy Ramesh
AU - B.G Bagley
AU - G.W Hull
AU - P.F Miceli
AU - Z.Z Wang
AU - D Brawner
AU - N.P Ong
AB - The effect on transport and superconducting properties produced by changes in x and y in the Nd2-xCexCuOy compound were studied in both polycrystalline ceramics and single crystals. Thermogravimetric analysis shows that the total oxygen content y for the as-prepared samples is always greater than 4 (i.e. presence of interstitial oxygen) whereas for the reduced sample y becomes equal to or smaller than 4 only when x is 0.15 or greater. This is the range of Ce content for which the material superconducts. For a material with Ce x=0.15 the superconducting properties can be varied reversibly by changing the oxygen content. In addition, we propose that the oxygen in these materials can be either ordered or disordered, thereby affecting the transport properties. Platelet-like crystals of Nd2-xCexCuOy with x=0 to 0.18, have been grown via a flux technique. Those having a Ce content between 0.14 and 0.17 are superconducting with the sharpest transitions (Tc = 21 ± 1K) for x = 0.14. Metallic-like behavior above Tc, with a linear temperature dependence above 150K was observed on all the crystals. Below 30K, the in-plane resistivity is independent of T. The Hall coefficient is sensitive to processing conditions but is usually negative above 100K. The upper critical field with field along the c-axis is 6T at 4.2K. © 1989.
BT - Physica C: Superconductivity and its applications
DO - 10.1016/0921-4534(89)91027-7
LA - eng
M1 - PART 1
N1 - cited By 35
N2 - The effect on transport and superconducting properties produced by changes in x and y in the Nd2-xCexCuOy compound were studied in both polycrystalline ceramics and single crystals. Thermogravimetric analysis shows that the total oxygen content y for the as-prepared samples is always greater than 4 (i.e. presence of interstitial oxygen) whereas for the reduced sample y becomes equal to or smaller than 4 only when x is 0.15 or greater. This is the range of Ce content for which the material superconducts. For a material with Ce x=0.15 the superconducting properties can be varied reversibly by changing the oxygen content. In addition, we propose that the oxygen in these materials can be either ordered or disordered, thereby affecting the transport properties. Platelet-like crystals of Nd2-xCexCuOy with x=0 to 0.18, have been grown via a flux technique. Those having a Ce content between 0.14 and 0.17 are superconducting with the sharpest transitions (Tc = 21 ± 1K) for x = 0.14. Metallic-like behavior above Tc, with a linear temperature dependence above 150K was observed on all the crystals. Below 30K, the in-plane resistivity is independent of T. The Hall coefficient is sensitive to processing conditions but is usually negative above 100K. The upper critical field with field along the c-axis is 6T at 4.2K. © 1989.
PY - 1989
SP - 285
EP - 290
T2 - Physica C: Superconductivity and its applications
TI - On the the crystal growth and chemistry of the new electron-type superconducting oxides
VL - 162-164
SN - 09214534
ER -