INVESTIGATION ON SYNTHESIS AND CHARACTERIZATION OF Hg1−xTlxBa2Ca2Cu3O8+δ WITH 0.2≤x≤0.8

Abstract

In the present investigation, Tl substituted Hg bearing cuprate high temperature superconductors corresponding to Hg 1−x Tl x Ba 2 Ca 2 Cu 3 O 8+δ with x=0.2, 0.4, 0.5, 0.6, 0.7 and 0.8, have been synthesized. The as synthesized phases characterized through XRD and TEM have been found to possess Hg:1223 as the dominant structural phase. These superconductors, with increasing Tl concentration have been found to pass from the underdoped through optimally doped to the overdoped regimes. The Tc for the underdoped regime (x=0.2) corresponds to ~117 K, for the overdoped regime (x=0.8), it is ~119 K. An interesting result emanating from the present study relates to the fact that an optimum Tc of ~122 K is obtained through oxygenation (annealing in oxygen) of the underdoped regime, reduction (annealing in Ar+H2) of overdoped regime, or else through optimum hole doping by suitable adjustment of substituted Tl concentration (x=0.6).