Abstract
In the current investigation, we report the impact of TiO2 nanowires (NW) and nanoparticles (NP) addition on flux pinning and superconducting characteristics of YB2Cu3O7-d (Y-123 or YBCO) material. Specimens were produced through solid-state reaction (SSR) route. The microstructure of samples showed an almost regular dispersion of nanometer scale entities for NP-added samples and a distribution of nanowires inside the grain boundaries for NW-added samples. The Y-123 phase structure was maintained with the addition of TiO2 nano-entities up to 0.1 wt%. An improvement of superconducting properties was observed for samples added with 0.1 wt% of TiO2 nano-entities compared to non-added one. Among all the prepared samples, a considerable augmentation of critical current densities in the absence and in the existence of applied magnetic fields was obtained for 0.1 wt% TiO2 NP added samples. The possible flux pinning mechanisms and correlation between the shapes of nano-entities, structure and superconducting properties was studied and discussed. An important result of the current study is that there is an increase of effective pinning centers and a complete change of vortex pinning mechanisms; from the fluctuation in the Tc(δTc) to the mean free path of the charge carriers (δℓ) for the 0.1 wt% TiO2 NP added sample compared to the non-added and 0.1 wt% TiO2 NW added samples.
•Impact of TiO2 nano-entities addition on superconducting properties of Y-123.•No phase transition in Y-123 structure with the addition of TiO2 nano-entities.•Transport electrical and magnetic properties are enhanced with TiO2 addition.•Possible flux pinning mechanisms were examined.•A change from δTc to δℓ pinning mechanisms is seen for TiO2 nanoparticles addition.