Formation Mechanism of Molybdenum and Molybdenum Oxide Nanoparticles by Electron Irradiation

Abstract

ABSTRACTThe mechanism of molybdenum and molybdenum oxide nanoparticles formation from molybdenum oxide microparticles by electron beam irradiation using a high-resolution transmission electron microscope on a room-temperature stage have been investigated. It is found that, the microsized molybdenum oxide particles disintegrated to form nanosized molybdenum oxide particles by electron beam irradiation with an intensity of approximately 1021e/cm2 · sec. The molybdenum nanoparticles were formed from molybdenum oxide nanoparticles upon further electron irradiation. During the electron irradiation process, the surfaces and interfaces of molybdenum oxide nanoparticles suffered damage and defects, such as vacancy arrays showing hole like spots and a moire-like fringes in the lattice image due to oxygen loss, followed by a gradual change from molybdenum oxide to molybdenum nanoparticles. The phenomenon of molybdenum metal nanoparticle formation from nanosized molybdenum oxide is considered to be due to desorption of oxygen as a result of electron stimulation and atomic displacement via the knock-on effect. It is suggested that electron irradiation is a powerful technique to create nanostructured metal, ceramic and semiconductor materials by atomic-scale control.