Structural and Superconducting Properties of CuTl-12(n-1)n; n = 3, 4/Nanostructures Composites

Abstract

Nanostructures/(CuTl) 0.5 Ba 2 Ca n-1 Cu n O (2n+4)–δ , {CuTl-12(n-1)n}; n = 3, 4} superconducting composites were synthesized by solid-state reaction (SSR) technique and their superconducting behavior was examined by different available experimental techniques. Anti-ferromagnetic chromium (Cr) nanoparticles (NPs), ferromagnetic cobalt (Co) and nickel (Ni) NPs, non-magnetic zinc (Zn) NPs and carbon nanotubes (CNTs) of different wt. % have been inserted in CuTl-12(n-1)n; n = 3, 4 superconducting matrices and their effects on the structure, morphology and composition was carried out by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. The transport properties and magnetic field response were explored by restivity versus temperature (RT) measurements with the help of four point probe method and ac-susceptibility (χ ac ) measurements, respectively. The experimental data was further analyzed theoretically by different models such as Aslamazov-larkin (AL), Lawrence-Donaich (LD) and Maki-Thompson(MT) models. It has been observed that the inclusion of different nanostructures (NS) in polycrystalline CuTl-12(n-1)n; n= 3, 4 superconducting matrices do not change their tetragonal structure and stichoimetry. Increasing concentrations of magnetic NPs (Cr, Co,Ni) additions in host CuTl-12(n-1)n}; n= 3, 4 superconducting matrices reduce the diamagnetic strength and superconducting volume fraction and cause suppression in characteristic superconducting parameters. The suppression of superconducting parameters after addition of these magnetic NPs can be accredited to spin scattering of carriers due to net magnetic moment, which tend to remain align in particular blocked state and oxygen disorder in superconducting regions. Non-magnetic Zn and CNTs also diminish superconductivity because of enhanced carrier scattering cross section at inter- crystallite sites. Theoretical fluctuation induced conductivity (FIC) analysis confirm the suppression of superconducting characteristic parameters by these NS inclusions in CuTl- 12(n-1)n}; n= 3, 4 superconducting matrices. Decrease in coherence length (ξ), increase in penetration depth (λ p.d ) and shifting of 3D regions towards lower temperature values illustrate the increased insulation at grain-boundaries and decrease in optimum charge carriesr density after addition of these NS in CuTl-12(n-1)n}; n= 3, 4 superconducting matrices