Formation of (Tl_1-x Cr_x)Sr₂CaCu₂O_7-s (Tl-1212) Superconducting Phase Using Cr₂S₃

摘要

The use of Cr2S3 to prepare the (Tl1-xCrx)Sr2CaCu2O7- (Tl-1212) superconductor phase is discussed.Samples with nominal starting composition (Tl1-xCrx)Sr2CaCu2O7- (Tl-1212) for x = 0.05, 0.10, 0.15,0.20, 0.25 and 0.30 were prepared by the solid state reaction method. Cr2S3 with lower melting pointthan the normally used Cr2O3 was employed for the Cr source. The samples were studied by powderX-ray diffraction method and electrical resistance versus temperature measurements. The sampleswith x = 0.05 and 0.10 showed a single Tl-1212 phase. A higher amount of Cr (x > 0.10) showed theTl-1201 as a minor phase. The onset transition temperature (Tc onset) was between 90 K and 105 K.Sample with x = 0.15 showed the highest Tc onset (105 K) and the lowest normal state electricalresistivity although it contained the Tl-1201 impurity phase. Our results showed that Cr2S3 could beeffectively used to prepare a high purity and high quality Tl-1212 superconducting phase.