Syntheses and Properties of HgBa2CaCu2O6+δ with Various Oxygen Contents

We synthesized nearly single phase HgBa2CaCu2O6+δ samples with various oxygen contents and studied the relations among the oxygen content, Tc, lattice parameter and the thermoelectric power. We succeeded in obtaining samples with a wide doping range from underdoped to overdoped states(Tc=90~127K) by annealing under a high oxygen pressure as well as annealing with reducing agent(Zr metal). The Tc showed a “bell shaped” dependence on the oxygen content y and a maximum at y~6. 21. A systematic increase in the hole density with y was also confirmed by the variation in the Seebeck coefficient.