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.