Reactive sputter deposition of CoCrCuFeNi in oxygen/argon mixtures

Thin films of (CoCrCuFeNi)O-x were deposited by direct current magnetron sputtering in a mixed O-2/Ar atmosphere. Stoichiometric films with a rock-salt (B1) crystal structure and a zone T microstructure were obtained at high oxygen pressures. HR-TEM and STEM studies demonstrated a homogeneous elemental distribution, the constituting metals are in a solid solution on the cation sites. This material system shows several similarities with sputtering the same alloy in a mixed N-2/Ar atmosphere: a textural change from a to a out-of-plane alignment occurs with the introduction of the reactive gas species and at high reactive gas flows, both systems achieve a B1 structure. The most profound difference is the higher incorporation rate of oxygen compared to nitrogen, which can be attributed to a larger electronegativity of the former element

Colloids of HEA Nanoparticles in an Imidazolium-Based Ionic Liquid Prepared by Magnetron Sputtering: Structural and Magnetic Properties

Colloids consisting of the CoCrCuFeNi high-entropy alloy nanoparticles in ionic liquid with the 1-butyl-3-methylimidazolium ([BMIM]+) cation and the tetrafluorborate ([BF4]-) anion were obtained by the DC magnetron sputtering of high-entropy alloy target in vacuum, onto the surface of [BMIM.BF4] ionic liquid. The method of the nanoparticle colloid preparation is based on negligibly small vapour pressure of the ionic liquid, which allows its application in vacuum. The high-entropy alloy nanoparticle colloids were studied by HRTEM microscopy and SQUID magnetometry. Results of the structural and magnetic analyses show that the colloids contain ultra-small single-crystalline nanoparticles of an uneven shape and typical size of (2−3) nm. The nanoparticles have relatively narrow size distribution which is typical for this preparation method. The high-entropy alloy nanocolloids show complex magnetic properties that are a function of temperature, applied magnetic field and mass content of the nanoparticles in the colloids. The obtained results imply significant magnetic interactions between the ionic liquid and the high-entropy alloy nanoparticles