The Effect of Ammonium Vanadate to Tamarind Fruit Aqueous Extract and PEG Mole Ratios on the Structure of W Doped VO2 Nanoparticles and Phase Transition Behavior

Abstract

This work aims to study the effects of ammonium vanadate : aqueous extract from tamarindpulp (TA) : polyethylene glycol (PEG) mole ratios on the crystal shape, size, and structure of 2% atomic tungsten doping vanadium dioxide (W doped VO₂) nanoparticles by using one-step hydrothermal method. The ammonium vanadate acts as the vanadium (+5) source. The TA and PEG act as the reducing agent and the particle distribution. The obtained products were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDX), and differential scanning calorimetry (DSC). From the results showed that at the mole ratio of NH₄VO₃:TA:PEG 5:0.01:0.2, the mixed phases of VO₂ (M) with VO₂ (B) and VO₂ (P) with 16 nm particle diameter of dark-blue spherical-like were crystallized. Meanwhile TA was increased at the mole ratios of NH₄VO₃:TA:PEG of 5:0.5:0.1, 5:1:0.1, 5:1.1:0.4, and 5:2.2:0.4, observed only VO₂(B) and VO₂(P) phases. DSC confirmed phase transition temperature (PTT) of VO₂(M) → VO₂(R) appeared at the range of 21-35°C and reversible phase of VO₂(R) → VO₂(M) at 36°C. In addition, observed PTT at 87°C due to mixed-phases of VO₂(B) and VO₂(P). Hence, the as-prepared W doped VO₂ can be applied for well infrared smart films at ambient temperature.