Synthesis and characterization of overdoped Hg-1234 and Hg-1245 phases; the universal behavior of Tc variation in the HgBa2Can−1CunO2n+2+δ series

The influence of oxygen content on the Tc of HTS Hg-1245

“…The change of a is caused by oxidation of copper because of nonstoichiometric oxygen in the Hg-O layer (the reservoir), that is, because of the hole density δ in the sample. The T c 's for phases Hg-1234 and Hg-1245 have a tendency in the overdoped state to merge with the overdoped phase Hg-1223 and to fall off abruptly [2].…”

“…The oxygen content in the starting mixtures was varied by changing the BaO/BaO 2 ratio, which allowed us to obtain the overdoped Hg-1223, 1234, and 1245 phases in as-preparated states. The technology of synthesis was described in detail in [1,2]. Special attention was paid to geting single phase ceramic specimens.…”

“…These states appear under heat processing of the as-preparated samples [2]. The change of a is caused by oxidation of copper because of nonstoichiometric oxygen in the Hg-O layer (the reservoir), that is, because of the hole density δ in the sample.…”

“…Numerous attempts at synthesis of layered cuprates with different elements added instead of mercury in recent years have failed to enlarge the T c max . We have synthesized the Hg-based cuprates with n = 3, 4, and 5 [1,2] and measured the T c max and the dT c max /dp for phases with n = 1-5 [3]. The largest T c max remained to be the value at n = 3.…”

The Correlation of Miller Indices with the Conductivity Mechanism of Cu-Based High-Tc Superconductor

“…The other attempts concentrated on the preparation condition of the applied method [4]. The last group depends on the partial substation of isovalent atoms [5] [6], and the change the parameter (n > 3) [7] [8] [9]. It was difficult to obtain the single phase of Hg-family ceramic compound because it contains both high phase Hg-1223 and low phase (Hg-1212).…”