A NEW HIGH-T-C SUPERCONDUCTING INTERCALATION COMPOUND

A new high-T-c superconducting intercalation compound, AgIBi2Sr2CaCu2O y, has been prepared either by reacting the silver metal directly with Bi2Sr2CaCu2Oy powders under P(I-2) similar to 1atm. at 190 degrees C or by the intercalation reaction between the iodine-intercalated Bi2Sr 2CaCu2Oy and AgI. According to the X-ray diffraction analysis, the obs erved basal increase of 7.35 Angstrom upon silver iodide intercalation indicates that the lattice expansion for AgIBi2Sr2CaCu2Oy is twice as large as that for the first-staged iodine-intercalated Bi2Sr2CaCu2Oy( Delta d approximate to 3.6 Angstrom). Such a result suggests the galle ry contains a double layer of iodine. A slight decrease in T-c for the AgIBi2Sr2CaCu2Oy (T-c approximate to 63K) compared to the pristine (T -c approximate to 76K) has been observed by the d.c magnetic susceptib ility measurements. The X-ray absorption spectroscopic results show th at there is no charge-transfer between guest species (AgI) and host la ttice. It confirms again that interblock-coupling has little effect on the superconductivity, since the T-c is not significantly evolved upo n AgI intercalation with a large lattice expansion along the c-axis wh ich is perpendicular to the (Cu-O) superconducting layers.