Near-infrared absorption properties of RbxWO3 nanoparticles

The rubidium tungsten bronze (RbxWO3) nanoparticles were synthesized by a solvothermal process in CH3COOH–C2H5OH mixed solutions for the application to near-infrared absorption materials. The as-obtained powder products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV-Vis-NIR spectra. The morphologies of samples were greatly changed as large irregular aggregates, aggregates of rod-like and irregular shaped nanoparticles and rod-like microparticles with increasing content of acetic acid in the starting solution. The sample synthesized in a 20 vol.% CH3COOH to 80 vol.% C2H5OH mixed solution consisted of the agglomerated particles of 50–100 nm in diameter, showing a highly disordered microstructure. Promoted by this disordered nature, the thin film of RbxWO3 nanoparticles realized excellent absorption of near-infrared light, meanwhile, it selectively transmitted the major part of visible light.