LOCAL CONFIGURATIONS IN ERBA2CU3O6+X FOR 0.15-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.9

PHYSICA C 235 (1994) 1261-1262

Authors:

M VAROTTO, G AMORETTI, C BUCCI, R DERENZI, G GUIDI, S JANG, P RADAELLI, C SEGRE

THE HG-BEARING CUPRATE SUPERCONDUCTORS - THE RELATIONSHIP BETWEEN THE OXYGEN-CONTENT AND T-C IN HG-1212 AND THE EFFECT OF PRESSURE ON THE STRUCTURE AND T-C IN HG-1223

EUROPEAN JOURNAL OF SOLID STATE AND INORGANIC CHEMISTRY 31:8-9 (1994) 843-854

Authors:

M MAREZIO, JJ CAPPONI, PG RADAELLI, PP EDWARDS, AR ARMSTRONG, WIF DAVID

TUNNEL-JUNCTIONS ON 1/2/4-Y-BA-CU-O SINGLE-CRYSTALS

PHYSICA C 235 (1994) 1913-1914

Authors:

P ROMANO, R DILEO, AM CUCOLO, A NIGRO, B DABROWSKI, PG RADAELLI

The irreversibility line of HgBa2CuO4+δ

Applied Physics Letters 63:5 (1993) 693-695

Authors:

U Welp, GW Crabtree, JL Wagner, DG Hinks, PG Radaelli, JD Jorgensen, JF Mitchell, B Dabrowski

Abstract:

Using magnetization hysteresis loops we have determined the irreversibility line of polycrystalline samples of HgBa2CuO4+δ and Hg0.8Pb0.2Ba2CuO4+δ. The irreversibility line is found at rather high temperatures. It does not show the drastic depression with increasing temperature as is observed in highly anisotropic Bi/Tl-based CuO superconductors. At 77 K the irreversibility field is around 0.3 T, which is substantially higher than in Bi2Sr 2CaCu2O8 and Bi2Sr 2Ca2Cu3O10. The advantages of this material for large-scale applications are outlined.

Structure, doping and superconductivity in HgBa2CaCu2O6+δ (Tc ≤ 128 K)

Physica C: Superconductivity and its applications 216:1-2 (1993) 29-35

Authors:

PG Radaelli, JL Wagner, BA Hunter, MA Beno, GS Knapp, JD Jorgensen, DG Hinks

Abstract:

We have studied the defect structure and superconducting propertiess of HgBa2CaCu2O6+δ by neutron powder diffraction, AC susceptibility and DC resistivity. An as-synthesized sample has an onset Tc of 128 K, the highest yet reported for this material. The critical temperature decreases slightly (126 K) after oxygenation, and drops to 92 K after reduction in flowing argon. Neutron diffraction data give evidence that the primary doping mechanism in this material is provided by oxygen atoms in an interstitial position, similar to the case of the one-layer compound HgBa2CuO4+δ. The occupancy of this site varies from 0.08 (1) for the argon-reduced sample to 0.22 (1) for the oxygenated sample. Unlike the case of the one-layer compound, no evidence of an additional defect site was found in these samples. HgBa2CaCu2O6+δ has remarkably long copper-apical oxygen distances and almost perfectly flat CuO2 planes. © 1993.