AC Susceptibility and Superconducting Properties of Te-Substituted TlSr₂Ca(Cu_2-xTe_x)O₇

Abstract

The effect of Te substitution on TlSr2Ca(Cu2-xTex)O7 for x = 0.2, 0.3, 0.4, and 0.5 was investigated. The solid-state reaction approach was used to prepare the samples. All TlSr2Ca(Cu2-xTex)O7 samples exhibited the presence of major Tl-1212 and minor Tl-1201 phases. Further Te replacement promoted the formation of the Tl-1201 phase. All samples demonstrated metallic normal state characteristics before onset transition temperature, Tc-onset. The resistance versus temperature curve for all samples revealed that the Tc-onset was between 46 and 40 K and the zero-resistance temperature, Tc-zero was between 29 and 37 K. The measurement of AC susceptibility revealed a susceptibility superconducting transition Tc χ' ranging from 30 to 36 K. This study showed that Te substitution stabilized the Tl-1212 phase, enhanced Tc χ’ although the Tc-onset and Tc-zero were below the boiling point of liquid nitrogen.