In situ high-temperature Raman scattering study of monoclinic Ag2Mo2O7 microrods

A N C Ferreira; W C Ferreira; A V Duarte; C C Santos; P T C Freire; C Luz-Lima; J V B Moura

doi:10.1016/j.saa.2023.122632

In situ high-temperature Raman scattering study of monoclinic Ag₂Mo₂O₇ microrods

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Jul 5:295:122632. doi: 10.1016/j.saa.2023.122632. Epub 2023 Mar 17.

Authors

A N C Ferreira¹, W C Ferreira², A V Duarte³, C C Santos¹, P T C Freire⁴, C Luz-Lima⁵, J V B Moura⁶

Affiliations

¹ Departamento de Física, Centro de Ciências Exatas e Tecnologia, Universidade Federal do Maranhão, CEP 65080-80, São Luís, MA, Brazil.
² Lyman Laboratory of Physics, Harvard University, Cambridge, MA 02138, USA.
³ Laboratório de Caracterização de Materiais, Centro de Ciências e Tecnologia, Universidade Federal do Cariri, CEP 63048-080, Juazeiro do Norte, CE, Brazil.
⁴ Departamento de Física, Campus do Pici, Universidade Federal do Ceará, CEP 60455-760, Fortaleza, CE, Brazil.
⁵ Departamento de Física, Campus Ministro Petrônio Portella, Universidade Federal do Piauí, CEP 64049-550, Teresina, PI, Brazil.
⁶ Departamento de Física, Centro de Ciências Exatas e Tecnologia, Universidade Federal do Maranhão, CEP 65080-80, São Luís, MA, Brazil. Electronic address: jvb.moura@ufma.br.

PMID: 36958242
DOI: 10.1016/j.saa.2023.122632

Abstract

In this work, we present a temperature-dependent behavior of monoclinic silver dimolybdate (m-Ag₂Mo₂O₇) microrods using in situ Raman scattering. The m-Ag₂Mo₂O₇ microrods were obtained by the conventional hydrothermal method at 423 K for 24 h. The structural and morphological characterization of the sample has been done by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Temperature-dependent Raman scattering measurements were performed on m-Ag₂Mo₂O₇ microrods, and the results show an irreversible first-order structural phase transition at 698 K-723 K and the melting process at 773 K. Changes in the Raman spectra confirm the phase transition from the P2₁/c monoclinic structure to the P-1 triclinic structure. No morphological changes were observed during the structural phase transition of the sample at 723 K. Time-dependent optical microscopy at 773 K showed the growth of nanowires on the Ag₂Mo₂O₇ microrods in the triclinic structure.

Keywords: Ag(2)Mo(2)O(7)microrods; High-temperature; Phase transition; Raman scattering.