NMR and EPR spectroscopic studies of fluorinated Bi-2212 HTSC

Abstract

NMR and EPR spectroscopy were used to analyse the structural changes caused by fluorination in Bi-2212 HTSC compounds. Synthesis of the fluorinated HTSC was carried out by a solid state method, using different fluorinating agents. The dependence of structural and superconducting properties on the nature and concentration of the fluorinating agent was explored. It was shown that substitution of fluorine for oxygen takes place in different preferred positions of the Bi-2212 lattice for different fluorinating agents; substitution in the {CuO 2 } layers, with formation of {CuO 3 F} and {CuO 2 F 2 } structural blocks, occurs in the best way when using PbF 2 , CuF 2 , BiOF and SrF 2 as fluorinating agents. An increase of T c was observed for the same fluorinating agents when added in optimal amounts.