A higher magnification image of the shell and core structure is shown in Figure 1b. The average particle size was 119 ± 73 nm. A TEM micrograph of the synthesized nanoparticles is shown in Figure 1a. In the original work, XRD analysis on the bulk samples revealed Cu, Cu 2O, and CuO phases in the powder. Results and Discussion Structure of particles This work can aid future researchers hoping to produce new types of core–shell particles using the electron beam evaporation method. Thus, the resultant particles are characterized in-depth in order to illuminate how they formed. As the electron beam evaporation method is a high-energy method, the reaction cannot be observed as it occurs. Thus, the current work attempts to use data from the two synthesized and particles to elucidate the mechanism by which the core–shell nanoparticles may form. As single-step synthesis of core–shell materials from elemental gas phase precursors has, to the authors’ knowledge, never been performed before, the mechanism of formation and the factors influencing the synthesis are unknown. Previous nanopowders synthesized with this method have been produced at kg/h rates. Thus, this method may also be a more economical method of synthesising certain types of core–shell particles. The precursors used are elemental materials rather than chemical compounds which are degraded into the final core or shell materials. In this method, the core–shell particles are synthesized in one-step directly from the gas phase without substrates. Recently, the authors have synthesized core–shell Ag–Si and Cu–Si type particles in a new way using electron beam evaporation. For these established techniques, the mechanisms of formation have been investigated and the various parameters which affect the particle formation are known. However these techniques also involve multiple steps, usually depositing the shell material onto an already formed core structure, and use substrates. Gas-phase synthesis techniques exist and usually involve chemical vapour deposition (CVD) or pulsed laser deposition (PLD). The majority of core–shell particles are synthesised using solution methods and usually involve two steps: synthesis of the core structure followed by coating the core structure with the shell material. Thus, they have found wide applicability in fields such as biomedicine, electrical and semiconducting materials, and catalysts.

Additionally, they have been designed so that the shell material can improve the reactivity, thermal stability, or oxidative stability of the core material or to use an inexpensive core material to carry a thin, more-expensive shell material. These particles have been of interest as they can exhibit unique properties arising from the combination of core and shell material, geometry, and design. Core–shell type nanoparticles are a type of biphasic materials which have an inner core structure and an outer shell made of different components.

Core shell nanoparticles wiki