The dependence of the properties of YBa₂Cu₃O_7–δ on the starting Ba compounds

Abstract

PACS 74.25. Fy, 74.25.Sv, 74.62.Dh, 74.72.Bk Y123 samples were prepared by a solid state method using BaCO 3 , BaO 2 and Ba(NO 3 ) 2 as Ba source under same sintering conditions. The X-ray patterns, T c , J c (77 K), stiffness, room temperature thermopower and lattice parameters were measured for as sintered, underdoped and well oxygenated samples. The results show these parameters are not the same for samples prepared using different Ba sources at different regime, reflecting the effect of Ba source on microstructure of Y123 compound.1 Introduction In spite of numerous experiments on Y123, there are still many questions to be answered and more works are needed to illustrate the mysterious of this compound.The authors, who have worked on Y123, could prepare the single phase of this compound successfully using different preparation methods and different starting sources of Y, Ba and Cu. But it is seen frequently that the results such as T c , J c , oxygen content, stiffness and other parameters are not quite the same. The differences are usually ascribed to different preparation methods [1,2]. Among all the factors, it seems that the initial starting compounds can have a special role on determining of properties and microstructure of YBa 2 Cu 3 O 7-δ [3,4].Agostino et al.[5] prepared the single phase of Y123 using different starting Ba compounds and they found that using Ba nitrate as precursor is the best choice for obtaining good quality superconductor samples.In this work, the single phase of Y123 samples were prepared by solid state method under the same conditions using BaO 2 , BaCO 3 and Ba(NO 3 ) 2 as the starting Ba compound. The samples were characterized by XRD, SEM, T c , J c (77 K), room temperature thermopower and stiffness measurements. The same measurements were performed on underdoped and oxygenated samples.A comparative analysis of results, showed that samples prepared using different Ba sources have their own advantages.