Bi2-Xhgxsr2-Ybaycacu2o8/Ag Sheath HTSC Wires, (Hg, Ba) Substitution Effect on the Critical Temperature

Abstract

Bi2-xHgxSr2-yBayCaCu2O8 High Temperature Superconductor (HTSC) has beenprepared as a pellet by solid state reaction with a certain substitution percentages (0,0.05 ,0.1) of Hg and Ba substitution instead of Bi and Sr respectively . Then, HTSCwires were fabricated from the prepared superconductor pellets using powder in tube(PIT) method utilizing silver as the tube material. The prepared wires are of three types;with monofilament MOF, 9 multifilament core 9MF and 81 filaments core(81MF).Several cycles of mechanical drawing and rolling process performed to the startingsilver tube of 0.4 cm diameter and 5 cm length to minimize the filament diameter. Theaverage filament diameter with 81MFC wire was about 25μm measured with an opticalmicroscope.Tc critical temperature for superconductivity is measured for the pellets and wiresusing four point probes techniques. These results show that the substation Bi by Hggive a rise to the superconductor to improve highly Tc , while substitution Sr with Balowers Tc .substitution of 0.05 , 0.1 Hg to the composition Bi2-xHgxSry-2BayCa1Cu2O8will raise the transition temperature (Tc) . Also substitution of Sr by Ba decreases thetransition temperature (Tc), Hg( 0.05 – 0.1 ) substitution still raise Tc after substitutionof Ba with (0.05 – 0.1). low – Tc phase (2212) , 2201 phase in B-2212 system and theaddition of Ag to silver sheaths and a small amount of impurity phases appear in theresult of XRD analysis.