Characterization of nano-InVO sub(4) powders synthesized by the hydrothermal process on various In/V molar ratio and soaking conditions

Various hydrothermal parameters such as the In/V ratio of starting materials, soaking time and additives were conducted to examine the resulting phase formation and particle morphology of InVO sub(4). The possible reaction during InVO sub(4) formation was proposed. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy and BET (Brunauer-Emmett-Teller) surface area measurement. Optical properties were investigated by UV-vis and Fourier transform infrared spectroscopy. The XRD patterns indicated a single InVO sub(4) phase formed at the starting In/V ratio of 1/2 and In(OH) sub(3), Na sub(2)V sub(6)O sub(16) coexisted with InVO sub(4) when the In/V ratio was 1/1 and 1/3, respectively. For the vanadium-rich samples (In/V = 1/3), the second phase of Na sub(2)V sub(6)O sub(16) increased with the increasing soaking time and demonstrated significant absorption in UV-vis spectra than pure InVO sub(4). The size and shape of InVO sub(4) particles could be tailored from rod-like into rounded square particles by PVP additives, acting as structure-directing-agent (SDA), up to 0.3 wt%.