Silica-supported erbium-based nanosystems: an XPS characterization

Silica-supported Er(III)-based nanocomposites were prepared by RF-sputtering from an Ar plasma. Depositions were carried out using an erbium target as a metal source and amorphous silica slides as growth surface. The substrate temperature was kept at 60 °C throughout each experiment. Attention was mainly devoted to the use of mild plasma conditions and to a proper choice of RF power, total pressure and deposition time in order to obtain a careful control of the deposited metal amount. Specimen characterization was performed by glancing-incidence x-ray diffraction (GIXRD), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) to investigate the structural, compositional and morphological properties of the obtained samples and their interrelations with the synthesis conditions. This study is dedicated to an XPS characterization of the principal core levels (Er, Si, O) of an Er(III)/SiO2 specimen obtained under selected conditions, leading to an incomplete silica coverage. This feature enabled investigation of the chemical state of both the deposited erbium-based particles and the supporting substrate. To this aim, detailed scans for the Er 4d, Si 2p, O ls, and C 1s regions and related data are presented and discussed.