Synthesis of oxide nanopowders with controlled size and morphology for application as materials for photonics and energy storage

Nanomaterials find application and extensive usage in many fields for their outstanding functional (e.g. electrical, optical, catalytic) properties and are becoming increasingly important in energy conversion and storage. The performance of devices in these fields strongly depends on the availability of starting materials with controlled size and morphology. Wet chemistry methods, such as hydrothermal or solvothermal syntheses, allow the production of highly monodisperse nanoparticles, with controlled size and morphology, or particles with engineered surfaces, through either functionalisation or the formation of core-shell particles. Nanocrystals with controlled shapes can be used for many applications. Due to their nonlinear properties, for example, LiNbO3 nanocubes act as novel efficient resonant nanostructures for the near ultraviolet range [1]. Starting from nanoparticles with highly controlled size, nanostructured advanced functional ceramics can be prepared through unconventional sintering techniques, such as spark plasma sintering. The properties of nanostructured materials, which strongly depend on their grain size, are largely investigated also to understand the fundamental limits of device miniaturisation, as in the case of barium titanate [2], a material largely used in multilayer ceramic capacitors. The controlled sintering of core-shell particles leads to functional polycrystalline materials with locally graded structure, showing strongly modified dielectric properties [3]. High k nanoparticles can be embedded in a polymer matrix for the fabrication of composite films with high breakdown field and high permittivity for energy storage. Depending on the embedded particle system and surface modification, devices with tailored properties can be obtained. References: [1] F. Timpu et al., Lithium Niobate Nanocubes as Linear and Nonlinear Ultraviolet Mie Resonators, ACS Photonics 2019, 6, 545 [2] Z. Zhao et al., Grain-size effects on the ferroelectric behavior of dense nanocrystalline BaTiO3 ceramics, Physical Review B 2004, 70, 024107 [3] M.T. Buscaglia et al., Synthesis of BaTiO3 Core-Shell Particles and Fabrication of Dielectric Ceramics with Local Graded Structure Chemistry of Materials 2006, 18, 4002.