Synthesis and properties of HgI2 intercalation of Bi2Sr2CaCu2Oy superconductor Original Research Article

Polycrystalline or single crystals of HgI2 intercalated Bi2Sr2CaCu2Oy (Bi2212) have been synthesized and their properties have been studied together with those of HgBr2 intercalates. Single crystals of HgI2 intercalated Bi2212 were synthesized by a stepwise intercalation method using iodine intercalate as a secondary host material. These could not be obtained through direct intercalation methods by which polycrystalline sample were obtained. From ac susceptibility and resistivity measurements, superconducting onset temperature (Tcon) for polycrystalline HgI2 intercalate was found to be 82 K which was higher than that of the host (75 K). On the other hand, Tcon for single crystal HgI2 intercalate was shown to be 79–80 K which is lower than that of host (95–97 K). The effect of HgI2 or HgBr2 intercalation on Tc tried discussion from the view point of hole doping and interblock coupling effect.