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