Tuning nanoparticle size for enhanced functionality in perovskite thin films deposited by metal organic deposition

Because of pressing global environmental challenges, focus has been placed on materials for efficient energy use, and this has triggered the search for nanostructural modification methods to improve performance. Achieving a high density of tunable-sized second-phase nanoparticles while ensuring the matrix remains intact is a long-sought goal. In this paper, we present an effective, scalable method to achieve this goal using metal organic deposition in a perovskite system REBa2Cu3O7 (rare earth (RE)) that enhances the superconducting properties to surpass that of previous achievements. We present two industrially compatible routes to tune the nanoparticle size by controlling diffusion during the nanoparticle formation stage by selecting the second-phase material and modulating the precursor composition spatially. Combining these routes leads to an extremely high density (8 × 1022 m−3) of small nanoparticles (7 nm) that increase critical currents and reduce detrimental effects of thermal fluctuations at all magnetic field strengths and temperatures. This method can be directly applied to other perovskite materials where nanoparticle addition is beneficial. An industrially compatible method for creating nanoparticles with controllable size has been demonstrated by a team in Japan and the USA. The thermoelectric and superconducting properties of a perovskite material can be improved by adding nanoparticles. But while a technique known as metal organic deposition enables high-performance materials to be grown, it is difficult to control nanoparticle size because it is determined by the diffusion of atoms. Now, Masashi Miura from the Seikei University/Los Alamos National Laboratory and co-workers have achieved a high density of tunable nanoparticles using metal organic deposition. They controlled diffusion by selecting the second-phase material and modulating the precursor composition. The team showed that BaHfO3 nanoparticles created in this way increased the critical current and reduced thermal fluctuations in a perovskite-composite cuprate superconductor. Nanostructural modifications, in particular nanoparticle (NP) additions, have been shown to have great success in improving energy-related material performance. We show how an economically viable method, namely metal organic deposition, can be used to obtain tunable small size (7 nm) and high number density NPs (8 × 1022 m−3) while maintaining the crystallinity of the perovskite-composite cuprate superconductor film matrix. Critical current density Jc(H) measurements demonstrate that the NPs are highly effective as pinning centers, decreasing vortex motion and fluctuation effects for all temperatures, magnetic field strengths and orientations measured. Our synthesis method can be applied to other perovskite-composite materials to improve their functionality.