Bulk nanocomposite made of ZnO lamellae embedded in the ZnWO4 matrix: growth from the melt

Monika Tomczyk,Iwona Jóźwik,Dorota A Pawlak,Marie-Helene Berger,Ryszard Diduszko,Pawel Osewski,Giorgio Adamo

doi:10.1007/s10853-021-06020-y

Abstract

Zinc oxide (ZnO) nanostructures exhibiting high exciton binding energy and efficient radiative recombination, even at the room temperature, are of increasing interest due to their prospective exploitation in optoelectronic and laser applications. However, attempts to synthesize well-ordered structures through simple and fast process have faced many difficulties. Here, we demonstrate a novel manufacturing method of ZnO lamellae embedded in a crystalline wide band gap dielectric matrix of the zinc tungstate, ZnWO4. The manufacturing method is based on a directional solidification of a eutectic composite, directly from the melt, resulting in a nanostructured bulk material. Electron microscopy studies revealed clear phase separation between the ZnO and ZnWO4 phases, and cathodoluminescence confirmed exciton emission at room temperature and thus high quality and crystallinity of the ZnO lamellae, without defect emission. Hence, utilization of directional solidification of eutectics may enable cost-efficient manufacturing of bulk nanostructured ZnO composites and their use in optical devices.Graphical abstract

Highlights

Zinc oxide has received much attention in recent years because it exhibits a wide range of favorable properties
Zinc oxide (ZnO) nanowires have the advantage of a high surface area and have demonstrated high sensitivity, even at the room temperature, whereas ZnO thin film gas sensors often need to be operated at elevated temperatures [6]
In order to demonstrate the possibility of utilizing directional solidification of eutectics for manufacturing ZnO nanostructured materials in a bulk form directly from the melt, we have grown rods with the eutectic composition of 65 mol % ZnO and 35 mol % of WO3, marked on the WO3-ZnO phase diagram in Fig. 1d [33]

Summary

Introduction

Zinc oxide has received much attention in recent years because it exhibits a wide range of favorable properties. ZnO is a wide band gap (3.37 eV) semiconductor that is suitable for short wavelength optoelectronic applications, and its high exciton binding energy (60 meV) can ensure efficient excitonic emission at room temperature [2]. ZnO may be considered for an extensive range of applications such as energy storage, sensors, cosmetic products, optoelectronic and electronic devices, among others [4]. ZnO nanostructures have received broad attention due to their unique properties [5]. They have been widely used for sensing applications because of their high sensitivity to the chemical environment. ZnO nanostructured films have been used in dye-sensitized solar cells as an electrode material [6]

Methods

Results

Conclusion