Temperature-dependent Phonon Dynamics of Ag3PO4 microcrystals

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 °C - 515 °C: Phase I (25 °C - 500 °C) → Phase II (515 °C - 590 °C). The phase transition is reversible and a temperature hysteresis was observed during the heating – cooling process: Phase II (590 °C - 470 °C) → Phase I (455 °C - 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.