MERCURY BASED CUPRATES - SINGLE-CRYSTALS GROWTH AND SUPERCONDUCTIVITY

Single crystals (n = 1, 2 and 3) of the Hg1-xMxBa2Can-1CunO2n+2+delta mercury based cuprates have been grown by using a simple process. The M cations (M = Bi, Cu, Ti) act as stabilizers of the structure which p ermit to avoid the use of dry box or high gas pressure. The electron m icroscopy coupled with EDX analyses evidence the regularity of the sta cking mode and confirm mixed mercury layers with compositions close to Hg0.8M0.2. Their structural studies based on X-ray diffraction data s how a splitting of the oxygen site at the level of the mixed mercury l ayer. These as-grown superconducting single crystals exhibit T-c close to that of the corresponding pure mercury ceramics. The pinning prope rties study performed on (Hg0.8Bi0.2) crystals confirms that the n = 1 member is intermediate between the n = 2 and n = 3 members. Moreover, the weak properties of the Hg0.6Ti0.4-1223 crystals with regard to th e Hg0.8Bi0.2-1223 crystals suggest that their different cationic radii Hg/M and their different c-axis values may play a role on these prope rties.