Low-Temperature Induced Phase Transitions In Bawo4:Er(3+)Microcrystals: A Raman Scattering Study

The synthesis of rare-earth-doped barium tungstate has increased in recent decades due to the attractive electrical and optical properties of the material. In this study, erbium-doped barium tungstate was synthesized by the co-precipitation method with three different concentrations: Ba(1-x)ErxWO4 (where x = 0.00, 0.01, and 0.02). The materials were characterized by X-ray diffraction (XRD), Raman and Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Subsequently, the samples were subjected to temperature variations in the range of 123-293 K, and their Raman spectra were collected to observe the structural changes induced by Er doping. We observed that at low temperatures, there was no indication of phase transition for pure tungstate (BaWO4); however, for doped tungstates, changes were observed in the Raman spectra, showing an unexpected structural phase transition. (C) 2019 Elsevier B.V. All rights reserved.