Synthesis of pure (ligandless) titanium nanoparticles by EB-PVD method

Abstract

Pure (ligandless) nanoparticles of titanium (4–20 nm) in a porous NaCl matrix (29–43 nm) were synthesized by the method of electron beam physical vapor deposition (EB-PVD). Independent electron beams were used to preheat the compacted cylinder from NaCl salt and Ti ingot up to formation of liquid melts. Evaporation of the initial materials from the melt surface, vapor flow mixing, and deposition of the mixed vapor on the surface of the water-cooled copper substrate took place in vacuum. Deposited condensate composition was regulated by the intensity of the vapor flows of evaporated materials. Results of studying the structure (SEM) and element composition of the condensate (EDS), phase composition (XPA), and the size of the nanoparticles (TEM) and crystallites (XPA + Scherrer equation), as well as their thermal stability in NaCl–Ti–O system (TGA), are given. It is shown that the dimensions and phase composition of titanium nanoparticles can be further controlled by heat treatment of the initial NaCl–Ti condensate, produced at low condensation temperatures. Investigations of the kinetics of oxidation of NaCl–Ti condensates in air (TGA) show that breaking of the vacuum in the chamber titanium nanoparticles in the porous NaCl matrix demonstrates high adsorption ability to moisture and oxygen from the air. With temperature increase up to 250–400 °C, practically all the moisture is removed, and further heating activates the process of titanium nanoparticle oxidation. Obtained results are considered from the viewpoint of physical and chemical adsorption.