Single and Multiple‐Step Dip‐Coating of Colloidal Maghemite (γ‐Fe₂O₃) Nanoparticles onto Si, Si₃N₄, and SiO₂ Substrates

Abstract

Abstract The adsorption behavior of colloidal maghemite (γ‐Fe 2 O 3 ) nanoparticles, passivated by oleic acid and dispersed in octane solution, onto three different substrates (Si, Si 3 N 4 , and SiO 2 ) is investigated. The average nanoparticle size is 10 nm, with a size variation (σ) less than 5 %. The adsorption of particles is strongly dependent on both the type of substrate and the particle concentration in solution. By a single‐dipping process, we have obtained a maximum coverage of 0.45 on a Si substrate, but much less on other substrates (0.19 on Si 3 N 4 and 0.14 on SiO 2 ). The particle coverage was drastically increased by the multiple‐adsorption process, where the process of dipping and drying was repeated multiple times. With this process, we can obtain a maximum particle coverage of about 0.76 on a Si substrate and 0.61 on a thermally grown SiO 2 substrate.