Synthesis and characterization of overdoped Hg-1234 and Hg-1245 phases; the universal behavior of T-c variation in the HgBa2Can-1CunO2n+2+delta seriesстатья
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Дата последнего поиска статьи во внешних источниках: 9 ноября 2013 г.
Аннотация:HgBa2Ca3Cu4O10+delta and HgBa2Ca4Cu5O12+delta were prepared by high pressure/high temperature technique. The phase composition in the Hg-Ba-Ca-Cu-O system was shown to be very sensitive io synthesis conditions. A variation of the oxygen content in the starting oxide mixture by changing the BaO/BaO2, ratio allowed the acquisition of Hg-1234 and Hg-1245 in the overdoped state. The heat treatments (nitrogen and oxygen flows, oxygen pressure 100 bar and 2000 bar) resulted in a change of T(c)s from initial overdoped (116 and 100 K for Hg-1234 and Hg-1245, respectively) to underdoped (95 and 85 K) and, finally, to optimally-doped states (125 and 111 K). The dependencies of T-c vs. alpha-parameter (and, consequently, oxygen content) for these phases exhibit a cupola-shaped behavior, as it was previously found for the lower (n less than or equal to 3) members of the HgBa2Can-1CunO2n+2+delta series. (C) 1998 Elsevier Science B.V.