  Pristine Antimony tungstate nanoparticles prepared via a simple hydrothermal
process showcase interesting photocatalytic efficiency, degrading Methylene
Blue (MB) completely in 180 min under visible light. In this study, the impact
on crystalline quality and related optical properties as well as photocatalytic
efficiency of antimony tungstate due to temperature variation during
hydrothermal synthesis are explored. While X-ray diffraction (XRD) shows the
polycrystalline nature of all synthesized samples, however a systematic
increase in crystallite size is revealed by analysing the XRD peak broadening.
XRD spectra are further examined by Rietveld analysis showing a change in unit
cell volume. Additionally, the overall changes in the corresponding grain size
and micro-strain developed in the crystals are determined using the
Williamson-Hall plot. Moreover, significant variations in few Raman modes are
observed with increasing synthesis temperature. A notable modification in the
optical band gap as determined from the absorbance of the UV-Vis spectra is
perceived with the change in synthesis temperature within the range of
~2.38-2.57 eV. Further, the photoluminescence measurement indicates that the
synthesized antimony tungstate is weak luminescent material with a band-to-band
emission at ~468 nm. Finally, photocatalytic efficiencies of the samples are
ascertained to change with the synthesis parameter, estimated by decomposing
methylene blue (MB), highest degradation rate constant (k) value is observed as
0.015 min -1 for the sample prepared at 180 o C. While the sample with the
highest efficiency is also applied for degrading the Rhodamine B (RhB) and
Potassium Dichromate (K 2 Cr 2 O 7 ) under visible light irradiation.
