Comparative study of dimensionality and superconducting parameters in YBCO-NaNbO3 nanoparticles- and nanorods-added composite sample from excess conductivity analysis

Excess conductivity and dimensional fluctuation effects on the superconducting parameters with the addition of nanoparticles (NPs) or nanorods (NRs) of NaNbO3 in polycrystalline YBa2Cu3O7-delta (YBCO) have been studied. Two series of samples were synthesized by solid-state reaction route on addition of 0.5 wt% to 2.0 wt% NaNbO3 NPs or NRs in pure YBCO superconductor. X-ray diffraction results show the unaffected orthorhombic crystal structure for all the synthesized samples. The field emission scanning electron microscope and high-resolution transmission electron microscope images reflect the addition of NPs or NRs in the YBCO material and indicate that the higher wt% of additive material leads to agglomeration of NPs or NRs. Using the Aslamazov-Larkin model, the fluctuation conductivity and the superconducting parameters such as coherence lengths, critical magnetic fields (B-C1(0) and B-C2(0)), effective layer thickness (d) and critical current densities (J(C)) have been estimated. It has been observed that 0.5 wt% concentration of addition of NaNbO3 NPs or NRs in YBCO compound shows significant enhancement in B-C1(0), B-C2(0) and J(C)(0), whereas a further increase in additive material results in a decrease in superconducting parameters. In comparison with the pure YBCO, the addition of NPs or NRs is causing a reduction in the magnetic vortex motion that leads to an enhancement in the vortex pinning capability which is responsible for increasing the B-C1(0), B-C2(0) and J(C)(0). Furthermore, a detailed analysis confirmed that the addition of NRs of NaNbO3 in YBCO is much more effective compared to the NPs for the same wt% of additive material.

Automated summary

The effects of adding NaNbO3 nanoparticles or nanorods to YBa2Cu3O7-delta (YBCO) on superconducting parameters were studied. The addition of NaNbO3 at a concentration of 0.5 wt% to 2.0 wt% in YBCO showed enhanced critical magnetic fields (B-C1(0) and B-C2(0)) and critical current densities (J(C)(0)), but further increase in additive material led to a decrease in superconducting parameters. The addition of NaNbO3 nanorods was found to be more effective compared to nanoparticles at the same wt% of additive material.