A Combined Experimental and Theoretical Study on the Formation of Ag Filaments on β-Ag 2 MoO 4 Induced by Electron Irradiation

Abstract

A combined experimental and theoretical study is presented to understand the novel observed nucleation and early evolution of Ag fi laments on β-Ag 2 MoO 4 crystals, driven by an accelerated electron beam from an electronic micro-scope under high vacuum. The growth process, chemical composition, and the element distribution in these fi laments are analyzed in depth at the nanoscale level using fi eld-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) with energy-dispersive spectros-copy (EDS) characterization. To complement experimental results, chemical stability, structural and electronic aspects have been studied systematically using fi rst-principles electronic structure theory within a quantum theory of atoms in molecules (QTAIM) framework. The Ag nucleation and formation on β-Ag 2 MoO 4 are a result of structural and electronic changes of the AgO 4 tetrahedral cluster as a constituent building block of β-Ag 2 MoO 4 , consistent with Ag metallic formation. The formation of Ag fi lament transforms the β-Ag 2 MoO 4 semiconductor from n- to p- type concomitant with the appearance of Ag defects.