Temperature-dependent phonon dynamics of Ag3PO4 microcrystals

J V B Moura; C D de Abreu Lima; E A O Melo; V E Santos; W C Ferreira; P T C Freire; C Luz-Lima

doi:10.1016/j.saa.2020.119339

Temperature-dependent phonon dynamics of Ag₃PO₄ microcrystals

Spectrochim Acta A Mol Biomol Spectrosc. 2021 Mar 15:249:119339. doi: 10.1016/j.saa.2020.119339. Epub 2020 Dec 13.

Authors

J V B Moura¹, C D de Abreu Lima², E A O Melo³, V E Santos³, W C Ferreira⁴, P T C Freire⁴, C Luz-Lima²

Affiliations

¹ Laboratório de Caracterização de Materiais, Centro de Ciências e Tecnologia, Universidade Federal do Cariri, CEP 63048-080, Juazeiro do Norte, CE, Brazil. Electronic address: victor.moura@ufca.edu.br.
² Departamento de Física, Campus Ministro Petrônio Portella, Universidade Federal do Piauí, CEP 64049-550, Teresina, PI, Brazil.
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.

PMID: 33360056
DOI: 10.1016/j.saa.2020.119339

Abstract

In this work, we present the study of the temperature-dependent behavior of silver orthophosphate (Ag₃PO₄) microcrystals using in situ Raman scattering. The Ag₃PO₄ as-synthesized microcrystals were prepared by the precipitation method and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman and infrared spectroscopy, and differential scanning calorimetry (DSC). Temperature-dependent phonon dynamics were performed on Ag₃PO₄ microcrystals and pointed to a first-order phase transition in the temperature range 500-515 °C: Phase I (25-500 °C) → Phase II (515-590 °C). The phase transition is reversible and a temperature hysteresis was observed during the heating - cooling process: Phase II (590-470 °C) → Phase I (455-25 °C). The reversible phase transition is related to the distortion of the tetrahedral symmetry of PO₄ caused by the decrease in the crystalline order. DSC analysis confirmed the results of temperature-dependent Raman spectroscopy.

Keywords: High temperature; Phase transition; Raman scattering; Silver orthophosphate.