Sputtering onto liquids: a critical review

Sputter deposition of atoms onto liquid substrates aims at producing colloidal dispersions of small monodisperse ultrapure nanoparticles (NPs). Since sputtering onto liquids combines the advantages of the physical vapor deposition technique and classical colloidal synthesis, the review contains chapters explaining the basics of (magnetron) sputter deposition and the formation of NPs in solution. This review article covers more than 132 papers published on this topic from 1996 to September 2021 and aims at providing a critical analysis of most of the reported data; we will address the influence of the sputtering parameters (sputter power, current, voltage, sputter time, working gas pressure, and the type of sputtering plasma) and host liquid properties (composition, temperature, viscosity, and surface tension) on the NP formation as well as a detailed overview of the properties and applications of the produced NPs.

Influence of Impurities on the Front Velocity of Sputter Deposited Al/CuO Thermite Multilayers

CuO and Al thin films were successively deposited using direct current (reactive) magnetron sputter deposition. A multilayer of five bilayers was deposited on glass, which can be ignited by heating a Ti resistive thin film. The velocity of the reaction front which propagates along the multilayer was optically determined using a high-speed camera. During the deposition of the aluminum layers, air was intentionally leaked into the vacuum chamber to introduce impurities in the film. Depositions at different impurity/metal flux ratios were performed. The front velocity reaches a value of approximately 20 m/s at low flux ratios but drops to approximately 7 m/s at flux ratios between 0.6 and 1. The drop is rather abrupt as the front velocity stays constant above flux ratios larger than 1. This behavior is explained based on the hindrance of the oxygen transport from the oxidizer (CuO) to the fuel (Al).

Optical and Electrical Conductivity of SnO:Cu Nanoparticles

This study included a different weight ratio of copper (2, 4, 6, 8) wt% as a dopant, with tin oxide SnO2 deposits on glass substrate by RF reactive magnetron sputter. The structural properties show polycrystalline pattern nature for all deposit samples with dominated reflection (110). The electrical conductivity increased to 1×13010 S-1 and the optical conductivity to 35×1016 S-1. The energy gap decreased to 3.60 eV when the rate of deformation was 8wt%, due to the increase in the crystallite size to 24.5 nm with the improvement of crystallization. While the surface measurements showed an increase in the surface roughness to 50 nm when the rate of deformation at 8wt%.