MoO3 fibers and belts: Molten salt synthesis, characterization and optical properties

Molybdenum trioxide (MoO3) powders with fiber and belt-like morphologies were synthesized through a molten salt method using NH4NO3 as a molten salt. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential thermal analysis (TG–DTA), Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible absorption spectroscopy. The results revealed that the amount of NH4NO3 and temperature had an important effect on controlling the morphology of the obtained molybdates. With increasing the temperature from 550 °C to 750 °C, and also changing the MoO3/NH4NO3 molar ratio from 1:4 to 1:7, the width of the particles increases and the fiber-like morphology changes to the belt one. Furthermore, the band gap energy of MoO3 decreased from 2.76 eV to 2.71 eV as the temperature increased from 550 °C to 750 °C.