A novel technique based on a low-temperature single-step solid state reaction of stoichiometric quantities of HgO and Ba2CuO3 to produce superconducting HgBa2CuO4+x samples has been developed. The `as-prepared' polycrystalline Hg-1201 samples had a T-c of 95 K, as obtained by the diamagnetic onset and resistivity measurements. The crystal symmetry was tetragonal with lattice parameters a = 3.876(1) Angstrom, and c = 9.509(4) Angstrom in agreement with literature data. Sample morphology consists of grains (average dimension 30 mu m) larger than in previously published works and of a needle-like structure embedding the whole sample. These results were highly reproducible over several batches. The resistive transition in magnetic field up to 8 T and a set of magnetic measurements is presented. From these measurements we obtain information about the irreversibility line, the critical current field dependence and the presence of weak links.
SYNTHESIS AND PROPERTIES OF SUPERCONDUCTING HGBA2CUO4+X FROM A SINGLE-STEP LOW-TEMPERATURE SOLID-STATE REACTION
BELLINGERI E;CIMBERLE;FERDEGHINI C;PUTTI M;SIRI;AS;COSTA;MASINI;
1994
Abstract
A novel technique based on a low-temperature single-step solid state reaction of stoichiometric quantities of HgO and Ba2CuO3 to produce superconducting HgBa2CuO4+x samples has been developed. The `as-prepared' polycrystalline Hg-1201 samples had a T-c of 95 K, as obtained by the diamagnetic onset and resistivity measurements. The crystal symmetry was tetragonal with lattice parameters a = 3.876(1) Angstrom, and c = 9.509(4) Angstrom in agreement with literature data. Sample morphology consists of grains (average dimension 30 mu m) larger than in previously published works and of a needle-like structure embedding the whole sample. These results were highly reproducible over several batches. The resistive transition in magnetic field up to 8 T and a set of magnetic measurements is presented. From these measurements we obtain information about the irreversibility line, the critical current field dependence and the presence of weak links.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.