Designing nanocomposites using supercritical CO2 to insert Ni nanoparticles into the pores of nanopatterned BaTiO3 thin films

Abstract

A new concept to prepare nanocomposite thin films is explored. Two chemical-based bottom-up steps are used to design functional films including (i) the block copolymer-assisted self-assembly of a porous matrix; and (ii) the impregnation of nanoparticles from a ferroic phase into the pores by supercritical CO₂ deposition. Porous nanopatterned BaTiO₃ thin films with ca. 17 nm thickness are prepared using a cost-effective sol–gel solution containing a block copolymer and evaporation-induced self-assembly methodology. Hexagonally arranged pores with a diameter of ca. 95 nm, running perpendicular to the substrate, are filled with Ni nanoparticles using the supercritical fluid deposition technique, obtained from the reduction of hydrated nickel nitrate in a supercritical CO₂–ethanol mixture at 250 °C. Small Ni nanoparticles of 21 ± 5 nm size are selectively deposited inside the pores of the porous matrix. Structural and magnetic properties prove the coexistence of both phases.