Doped vanadium dioxide by hydrothermal and green processes: synthesis and physical properties

Abstract

Nanomaterials are of great interest because of their novel electrical, optical and magnetic properties which results from their small size and shape and exhibit unique features that are significantly different from their corresponding macro state. Nanomaterials synthesis, therefore, has been an important research topic due to promising signs of their implementation for various kinds of device applications. It is well-known that vanadium dioxide is a thermochromic material and exhibits metal-insulator transition close to room temperature of about 680C. This metal-insulator phase transition of vanadium dioxide is followed by changes of optical properties such as increase in reflectance and decrease in emittance in the infrared region when the temperature increases above the transition value. Due to this anomalous property, vanadium dioxide is a suitable candidate material for various device applications as in optical switches, smart-window coating for energy efficiency buildings, energy storage devices, sun screening, thermal sensor, and smart radiation devices. This research project focuses on the successful synthesis and characterization of thermochromic vanadium dioxide nanomaterials and consists of two parts. The first part of the thesis consists of hydrothermal synthesis method for the successful synthesis of undoped and Mg-, Cr-, Mo-doped vanadium dioxide nanoparticles. This is due to low cost, high throughput, environmental friendliness and scalability of the technique for large scale production. The second part of this thesis encompasses the synthesis of vanadium dioxide nanoparticles by green processing. The second part was carried out because it is nontoxic, an environmentally friendly approach and has never been done before, as to our knowledge, for the synthesis of vanadium oxides nanoparticles. All results were characterized by using XRD, SEM, HRTEM, DSC, and FTIR techniques.