Thermo-Raman investigations on structuraltransformations in hydrated MoO₃

Thermally induced structural transformations in hydrated MoO₃ prepared by acidification of Na₂MoO₄ solution have been investigated dynamically by thermo-Raman spectroscopic techniques. The thermo-Raman spectra reveal that the structural evolution of as-synthesized hydrated MoO₃ in air proceeds through an amorphous phase after dehydration processes, formation of sub-microcrystals, the MoO₃-II phase (possible) and the α-MoO₃ phase in a dynamic thermal process. The thermo-Raman results are supported by thermogravimetry, differential thermal analysis, differential scanning calorimetry and powder X-ray diffraction results. The structural evolution of as-synthesized hydrated MoO₃ under nitrogen gas flow was also investigated by thermo-Raman studies.