Mn-doped nanometer-size ZnS clusters in chitosan film matrix prepared by ion-coordination reaction

Abstract

A novel method, the so called ion-coordination reaction, was introduced to prepare nanometer-sized Mn-doped ZnS clusters stuck to a chitosan medium. A possible growth mechanism of the Mn-doped ZnS clusters in a chitosan film has been proposed. The X-ray diffraction showed that the ZnS clusters have a cubic structure like bulk crystals and the cluster sizes were estimated from the diffraction linewidth to be 2–4 nm based on Scherre's equation. The emission of Mn ion was observed through band-to-band excitation of ZnS. The excitation spectrum showed a large blue shift relative to that of ZnS bulk material. The effect of Zn ion concentration on the luminescence intensity reveals that the emission efficiency of Mn ion increases with the decrease of the ZnS cluster size.