Researchers Use Raman Spectroscopy to Study Phase Transition of Monoclinic Silver Dimolybdate Microrods at High Temperatures

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An in situ high-temperature Raman scattering study of monoclinic m-Ag2Mo2O7 microrods reveals an irreversible first-order structural phase transition and melting process, according to new research.

Researchers at Universidade Federal do Maranhão in São Luís, Brazil, have conducted an in situ high-temperature Raman scattering study of monoclinic silver dimolybdate (m-Ag2Mo2O7) microrods. The study, published in the Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal, explored the temperature-dependent behavior of the m-Ag2Mo2O7 microrods and found an irreversible first-order structural phase transition at 698 K–723 K and a melting process at 773 K (1).

The researchers obtained the m-Ag2Mo2O7 microrods by using the conventional hydrothermal method at 423 K for 24 h. Then, they conducted structural and morphological characterization of the sample using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The Raman scattering measurements were performed on m-Ag2Mo2O7 microrods to determine the phase transition, and doing so revealed changes in the Raman spectra, confirming the transition from the P21/c monoclinic structure to the P-1 triclinic structure.

Monoclinic silver dimolybdate (m-Ag2Mo2O7) microrods have potential applications in various fields, such as catalysis, electrochemistry, and gas sensing. The study of their structural and morphological properties, as well as their temperature-dependent behavior, is important for understanding their potential applications and for developing new ones. The in situ high-temperature Raman scattering study of m-Ag2Mo2O7 microrods presented in the article provides valuable insights into their phase transition behavior and melting process, which can inform future research on this subject.

Interestingly, no morphological changes were observed during the structural phase transition of the sample at 723 K. However, time-dependent optical microscopy at 773 K showed the growth of nanowires on the Ag2Mo2O7 microrods in the triclinic structure. This study provides significant insights into the temperature-dependent behavior of m-Ag2Mo2O7 microrods and their potential use in high-temperature applications.


This paper, with lead author J.V.B. Moura, indicated that Raman spectra provide important insights into the high-temperature phase transition behavior of m-Ag2Mo2O7 microrods, which is essential for their practical applications in various fields. This study could lead to further research on the phase transition behavior of other materials and could potentially open up new avenues for their use in high-temperature applications.

Overall, this study highlights the importance of understanding the temperature-dependent behavior of materials and their potential for practical applications. The findings of this study could have significant implications in various fields, such as materials science, chemistry, and physics.


(1) Ferreira, A. N. C.; Ferreira, W. C.; Duarte, A. V.; Santos, C. C.; Freire, P. T. C.; Luz-Lima, C.; Moura, J. V. B. In situ high‐temperature Raman scattering study of monoclinic Ag2Mo2O7 microrods. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2023, 295, 122632. DOI: 10.1016/j.saa.2023.122632